bluuebunny/crossref_metadata_2025 huggingface dataset:
Universal Design of Transportation Systems: A Case Study of Access and Mobility of People with Disabilities at Selected Intersections in Dar es Salaam
Authors: Mushule Nurdin K.
Published: March 2021

The pedestrian facilities at intersections must be usable by pedestrians of all ages and capabilities. Intersections in particular must be designed to safely accommodate pedestrians of all ages and physical and mental abilities. Often, however, intersection designs fail to accommodate people with visual and mobility disabilities. In this regard, forpedestrians with disabilities, intersections can prove to be a challenge. Some of those challenges include provision of insufficient pedestrian clearance time due to use of inappropriate design pedestrian speed. Most importantly, the required facilities to enable People With Disabilities (PWD) to use the intersection without hindrance may be missing.Obstacles such as uneven surfaces, unstable surfaces, nonexistent curb ramps, road crossings, changes in height of sidewalks, nonexistent guidance systems, obstructions, vegetation overhanging sidewalks, poles in the sidewalk, holes, etc. can all be remedied. This paper presents the results of the study which was carried out in Dar es Salaam toevaluate the extent to which the design of intersections satisfies the mobility and access needs of people with disabilities. The results indicate that the design of 20 major intersections in Dar es Salaam, mostly does not pay due attention to the needs of PWD.
Analysis of Factors Affecting Technological Innovativeness in Engineering Enterprises in Tanzania
Authors: Mjema Emmanuel A.
Published: March 2021

This paper discusses the technological innovativeness in engineering enterprises in Tanzania and analyses the factors affecting the innovativeness. It starts by analyzing various concepts regarding innovation, then analyzed from documentary review factors affecting innovativeness and then analyzed the innovativeness in Tanzanian enterprises.From the documentary review it was learnt that the following key factors influence technological innovativeness: Existence of innovation management; Existence of market to absorb the products of innovation; Existence of partnership between the universities and the firms; Existence of positive culture and politics towards innovation; The governmentplaying its role to influence innovation; Existence of the right knowledge; and Ability of the enterprises to access to financing institutions that support innovation.The research shows that there is hardly any fundamental innovation in Tanzania, what is presented as innovation is the copying of technologies and manufacture them using local material. Theresearcher established the following factors affecting the innovativeness of engineering enterprises in Tanzania: Level of education among the entrepreneurs in engineering enterprises; financing for the enterprises in Tanzania; partnership with R&D institutions; innovativeness culture; and market for Tanzanian products.
Open Source Kiswahili Spell Checker (SW-TZ)
Authors: Twaakyondo Hashim M. , Mwakisole Kennedy
Published: March 2021

Different English software products are localized into many native languages spoken around the world, the most popular software products localized so far are word processing software and web browsers. The effort has begun to localize these software products in Kiswahili language which is widely spoken in Tanzania, East and Central Africa. Kiswahiliis an official language of Tanzania, and is a national language in Uganda and Kenya. To make these software products useful to Kiswahili speaking community particularly in Tanzania a new Kiswahili spell checker has been developed and, it uses most of the Kiswahili words spoken in Tanzania and its locale identity is sw-TZ for OpenOffice.org and Mozilla Firefox while Kiswahili spoken in Kenya has a locale identity sw-KE which is common for Microsoft office products. It was developed due to the shortcomings of first ever Kiswahili spell checker developed by Open Kiswahili Localization Project(KILINUX). A spell-checking tool called MySpell has been used in developing a new spell checker. The dictionary of a new spell checker consists of 4894 stems and its affixes were created based on Kiswahili noun classification system and by selecting different groups of verb stems that follow the same trends in generating other Kiswahili valid words. Thispaper addresses the shortcomings of the existing spell checker and the approach carried out to develop a new spell checker.
Isolation and Characterization of Micro-organisms with Industrial Importance From Sisal Bole Rots
Authors: Mhaiki Consolatha J.N. , Masanja Enock , Katima Jamidu H.Y. , Rajarao Gunaraths , Dalhammar Gunnel
Published: March 2021

Investigation of microorganisms naturally acclimatized to Agave hybrid H 11648 (sisal bole rot) was conducted, with the aim of isolating and characterizing Aspergillus niger strains for industrial use. Microorganism were identified morphologically and then confirmation made by polymerase chain reaction (PCR). Results showed the existence of four major groups, listed in order of abundances as follows; Aspergilli (36.0±0.8) %, Penicillin (28.0±0.1) %, Yeast (15.0±1.6) %and Fusarium (10.0±0.12) %. The main groups of Aspergilli strains were A. nidulans, A. tamari and A. niger in ratios (3:2:2), respectively. Several endo-spore forming non-enteric gram (-) rods and coccid bacteria identified by API20 NE identification systemincluded,Brevundimonas diminuta sp, Shewanella putrefaciens sp, Brevundimonas vesicularis sp and Pasteurella sp. Results showed that sisal bole rot stems hosts a high bio-diversity of microorganism species other than A. niger. Exploitation of the individual strains is recommended. This could eventually produce strains forprecursors of industrially and therapeutically metabolites.
Gas Leakage Detection System (GLDS)
Authors: Simbeye Daudi S.
Published: March 2021

This paper mainly focuses on the detection of gas leakage and providing security when the user is around or away from home. The system is Short Message Service (SMS) based and uses wireless technology for providing security against gas leakage to users hence cost effective and more adaptable. The system comprises of sensors for detecting gas leakinterfaced to microcontroller that will give an alert to user whenever there is a gas leakage, display warning information by using Liquid Crystal Display (LCD), sending SMS to the user for notification wherever he/she might be and turning off electric power with the help of magnetic relay. This will enable the user to take precaution of explosion disaster whichmay result on Liquefied Petroleum Gas (LPG) cookers like loss of properties, injury or even death. GLDS provides ideal solution to gas leakage problems faced by home owners in daily life.
2D AutoCAD Geometric Data Extraction and Post- Processing for Numerical Control
Authors: Mwinuka Tito E. , Mutagahywa Beda M.
Published: March 2021

In this paper, a method of extracting 2D geometric data from AutoCAD drawing and post- processing for Numerical Control (NC) is presented. Geometric data already available in the Drawing Interchange Files (DXF) can be utilized to accurately and economically prepare part programs for controlling NC/CNC machine tools. AutoCAD, being generalpurpose software, stores its geometric data in a form that cannot be directly applied for automatic generation of Numerical Control (NC) codes. The way around the discrepancy between the structure of a drawing database (DXF files) and the information requirement for part programming is addressed in this work. NC programming of a test componentdrawn in AutoCAD is also presented.
Analysis of Power Efficiency of a Direct-Driven Locally Fabricated Permanent Magnet Ac Generator for Small-Scale Wind Power Applications in Tanzania
Authors: Msuya R.A. , Kainkwa R.R. , Mgwatu M.I.
Published: March 2021

The use of direct-driven permanent magnet alternating current (AC) generators offers the opportunity to reduced costs and increased system efficiency. This type of generator could be the best alternative for rural population whom are not connected to the national grid. To improve the design and efficiency of locally fabricated generators, it is imperative tocharacterize both their mechanical and electrical parameters. This paper presents the analysis of power efficiency of the synchronous permanent AC generator locally fabricated in Tanzania. In this case, load resistance and rotational speed are characterized using designed experiment. The output current and voltage of the generator were recorded simultaneously in each step change of load resistance and rotational speed. The output power and efficiency were then determined analytically. The results show that there is a linear relationship between voltage and rotational speed of the generator with and without load resistance. The results further indicated that out power is not linearly related to rotational speed. The generator•s power efficiency was found to be about 55% against both the output voltage and rotational speed.
Thermolysis and Kinetics of Scrap Tyre and Bagasse for Energy Utilization
Authors: Ndalila Petro , Mhilu Cuthbet F. , John Geoffrey R.
Published: March 2021

The increase of energy demand has brought concern to find alternative fuel that will at least sustain the requirement. Bagasse and scrap tyre are waste generated in our industrial activities, which can be used in energy production to subsidize the demand. This paper, aim to study the decomposition behaviour and kinetics of biomass (bagasse) and scrap tyre as preliminary stage of fuel sample analysis to be considered for energy production in gasification/combustion or pyrolysis facilities. The behaviour demonstrated with thermogravimetric analyzer (TGA), shows that all samples have high volatile amount release, 84.21% for bagasse and 85.08% for scrap tyre, which means all are suitable for pyrolysis. However, scrap tyre is most suitable for gasification or combustion due to its high energy content, high ash content and low moisture than bagasse. The determined kinetic parameter were activation energy (E) and pre-exponential factor (A) for hemicellulose/oil as first release composite and cellulose/elastomer as second composite of the analyzed bagasse/scrap tyre samples. The hemicelluloses of bagasse exhibited highest value of activation energy and pre-exponential factor (E=178.191 kJ/mol, and A=1.74×10 16 ) than oil of scrap tyre (E=41.113 kJ/mol, and A= 495.5), which means bagasse is suitable candidate for gasification process due to high operating temperature. With this respect of the study, all candidates may be suitable for pyrolysis or gasification/combustion process. However, for environmental consideration scrap tyre is not suitable due to high sulphur (S) and nitrogen (N) content resulting to high emission ofSOX and NOX .
Effect of Temperature and Slice Size on Avocado Pulp Drying Rate and Oil Yield
Authors: Temu Abraham T.
Published: March 2021

The effect of temperature and slice thickness on avocado pulp drying rate and oil yield was determined at 50 o C, 60 o C and 70 o C. Pulp slices of 2mm and 5 mm thick were used. The avocado pulp was found to contain 74-75% (wet basis) water, which makes extraction of oil by both chemical and mechanical means difficult. Experimental results showed that oil yield increased with decreasing moisture content reaching a yield of 61% at 10% moisture content. The rate of drying increased with temperature, but decreased with slice thickness. The drying data obtained agreed well with several thin-layer drying models. The models showed that the characteristic drying constant increased linearly with drying temperature and decreased with slice thickness. The Physico-chemical properties of the obtained oil compared favorably with those obtained from other conventional seed oils.
Application of Remotely Sensed Rainfall Data in Rainfall-Runoff Modelling. A Case of Pangani River Basin, Tanzania
Authors: Nobert Joel , Kibasa Patric
Published: March 2021

Rainfall runoff modelling in a river basin is vital for number of hydrologic applicationincluding water resources assessment. However, rainfall data from sparse gauging stationsare usually inadequate for modelling which is a major concern in Tanzania. This studypresents the results of comparison of Tropical Rainfall Measuring Mission (TRMM)satellite rainfall products at daily and monthly time-steps with ground stations rainfalldata; and explores the possibility of using satellite rainfall data for rainfall runoffmodelling in Pangani River Basin, Tanzania. Statistical analysis was carried out to find thecorrelation between the ground stations data and TRMM estimates. It was found thatTRMM estimates at monthly scale compare reasonably well with ground stations data.Time series comparison was also done at daily and annual time scales. Monthly and annualtime series compared well with coefficient of determination of 0.68 and 0.70, respectively.It was also found that areal rainfall comparison in the northern parts of the study area hadpoor results compared to the rest of areas. On the other hand, rainfall runoff modellingwith ground stations data alone and TRMM data set alone was carried out using five Real-Time River Flow Forecasting System models and then outputs combined by Models OutputsCombination Techniques. The results showed that ground stations data performed betterduring calibration period with coefficient of efficiency of 76.7%, 81.7% and 89.1% forSimple Average Method, Weight Average Method and Neural Network Method respectively.Simulation results using TRMM data were 59.8%, 73.5% and 76.8%. It can therefore beconcluded that TRMM data are adequate and promising in hydrological modelling.
Accuracy of Dem-Based Topographic Data in Flood Inundation Modelling: A Case of Wami River, Tanzania
Authors: Ndomba Preksedis M.
Published: March 2021

The objective of this paper is to evaluate and further comment on the accuracy of the DEM-based topographic data as input in flood modelling. Recent studies have indicated thathydraulic parameters of the modified cross sections based on high resolution DEM aregeometrically and hydraulically similar to the measured ones. In the current study hydraulicmodelling was intended to guide a development project whereby a floodplain protectionembankment is contemplated. Therefore, accuracy in terms of positioning/alignment of naturalfeatures such as river banks and heights/elevations was imperative to attain. In order to achievethese, accuracy of various topographic data sources were qualitatively and/or quantitativelyanalysed before and after hydraulic modelling. As the study river reach is ungauged, thehydraulic model was verified and validated with field observations, readily availableinformation and professional judgement. Based on error analysis, it was found thatuncalibrated 90-m resolution STRM DEM-based topographic data are biased, i.e., 80% of theerror mass is negative. The error increases with elevation. The final input to the hydraulicmodel was a composite/hybrid DEM derived after merging geometric data from fourrepresentative field-measured cross sections, a 2-m interval contour map covering part of theriver valley, and calibrated 90-m resolution DEM. Although, calibration improves the data, itdoes not remove completely the inherent bias. Further to DEM calibration, it was thereforerecommended to include an elevation uncertainty value of -0.5 m, as derived from topographicanalysis, into simulated water surface profiles elevations. The hydraulic model satisfactorilysimulated flood inundation extent after considering the elevation uncertainty. In order toimprove the findings further studies should use adequate measured cross sections and DEM ofhigher resolutions.
Noise Pollution in Maize Milling Smes
Authors: Elias Erasto , Majaja Bashira A. , Ibrahim Said , Kizima Emmanuel G.R.
Published: March 2021

Maize milling SMEs emit high levels of noise which can have adverse effects on humanbeings and therefore require controlling. This paper reports on a study that involvedassessment and measurement of noise level in maize milling SMEs in DSM and Morogorourban, gathering opinions of workers and the neighbouring population on noise problems,and suggesting solutions for noise control. Noise measurements in 41 SMEs were recordedfrom 89-103 dBA in DSM and 92-103 dBA in Morogoro near the milling machines. Thesevalues were higher than the safe level of 85 dBA for 8 hours working shift. Measurementalso indicated high noise in the immediate neighbourhood of the milling plants. Machineoperators and neighbours indicated health problems which could be a result of machinenoise. Causes of high noise were identified to include loose or untightened machine parts,improper installation of machine system, use of worn out machine bearings, and the use ofimproperly designed and unbalanced milling hammers. Possible administrative andtechnical solutions for these problems were suggested. It is concluded from this study thatmost of maize milling SMEs produce high noise which is indeed pollutant to workers andthe neighbouring population. Therefore, it is important to implement the suggestedadministrative and technical solutions to minimise this problem.
Lemongrass and Cinnamon Essential Oils as Vitamin C Preservatives and Flavour Enhancers in Jam
Authors: Byarushengo Denice , Minja Rwaichi , Temu Abraham
Published: March 2021

Lemongrass and cinnamon essential oils (LEO and CEO) are natural oils with high anti-oxidation capacity, pleasant flavour, and various health benefits. Their ability to preservevitamin C and flavour in jam have not been tested. In this study the performance of twoessential oils (EOs) in preserving vitamin C and improving jam flavour were investigated.The EOs were produced by hydro-steam distillation of fresh lemongrasses and cinnamonleaves using a Clevenger apparatus. Jam samples were dosed with various concentrationsof either single or mixed EOs and then stored at either room or refrigeration temperature.Samples were analysed for changes in vitamin C content and flavour, after every 10 daysfor 60 days. Vitamin C content was determined using 2,6 dichlorophenol indophenol visualtitration method, whereas sensory analysis was done by five semi trained panellists. It wasrevealed that both LEO and CEO have high potential to reduce loss of vitamin C andimpart better flavour in pineapple jam. The improved quality of the jam is due to anti-microbial and anti-oxidant effects of the essential oils as reported in literature. Mixing theEOs had synergistic effect which maximizes their potential to reduce vitamin C loss withlower dose than when used individually. Mixed EOs doses also enhanced the jam flavour.
Analysis of Different Techniques for Improving Performance of Flat Plate Solar Collectors for Fruits Drying
Authors: Bakari Ramadhani , Minja Rwaichi , Njau Karoli
Published: March 2021

Fruits drying had become a broader technology in fruits and vegetables value addition.The technology is reported to be a promising way of drying without incurring higher costbut its adaptation has not been feasible in rural areas. Solar dryers have been developedbut its poor performance limits its applicability. In this study, several techniques formodifications of traditional solar collector were addressed. It was observed that, varyingcollector designs in different techniques, a range of collector performances can bearchived. The research shows that, collector efficiency can be improved by 9.6% whenemploying double duct counter flow compared to conventional collectors. Likewise,performance difference between conventional collectors and studied models were found tobe 8%, 7.2%, 6.1% and 5.2% for model parked with charcoal, 5 mm wire mesh, 4 mmglass thickness and 8 baffles respectively. This study shows that, double duct counter flowsystem is the best option for improving the performance of the collectors, followed bycharcoal and wire mesh. On the hand, using 4 mm glass thickness gave improvedperformance, however, it is recommended for collector size not exceeding 2 m in length.
Properties of Boards Made from Rice Husk and Portland cement As Binders and Reinforced with Sisal Fibres
Authors: Mrema Alex Lyatonga
Published: March 2021

A research study demonstrated that rice husks can be used to manufacture boards whichcan be used in low cost housing if bound by Portland limestone cement (CEM II/A-L/32.5R) and reinforced with sisal fibers to cater for their brittle behavior and that suchboards can provide a substitute for wood panels. Boards made of rice husks and cement inthe ratios of 1/3.3, 1/ 3.6 and 1/4 and with sisal fiber reinforcement contents of 0%, 0.4%,0.5% and 0.8% were prepared and tested for their physical and mechanical properties. Theresults were compared with standard requirements for boards made with wood based fiberand particle panel materials according to DIN 1101 and ISO 2696 and BS EN 634-2.Results indicate that water absorption and thickness swelling decreased with an increase infiber content and that there is an optimum rice husk/ cement ratio and fiber content thatgives maximum flexural strength and that such boards could be used in low cost housingconstruction. The use of such boards could be seen as partially solving the problem ofglobal warming and the problem of pollution associated with the disposal of rice husks indeveloping countries.
Loss Modeling of A Permanent Magnet Dc Motor Drive Water Pumping System
Authors: Lujara Nelson K.
Published: March 2021

The paper presents an analytical approach to the determination of losses in each of thesub-systems of the Photovoltaic (PV) Permanent Magnet DC Motor (PMDC) drive waterpumping system with and without maximum power tracking. The losses of the system atvarying heads are firstly, determined using parameters from the data sheets and thenvalidated by experimental results. The results are used to establish the head and the flowrate optimal operating point of the system.
Design and Manufacture Of A Waste Compactor Prototype: A Step towards Implementing A Non-Burn Health Care Waste Disposal in Developing Countries
Authors: Mwinuka Tito E. , Nyichomba Bavo B.
Published: March 2021

Non-burn technology is the only safe way of handling and disposing infectious healthcare waste. It involves steam treatment of infectious waste at temperatures higher than 121 o C for a minimum of 30 minutes before disposing them just like other municipal waste. Infectious healthcare waste is normally only about 10 -25% of all healthcare waste. In this paper, design, manufacturing and testing of a waste compactor for reducing waste volume to facilitate its handling is discussed. Preliminary tests show that the waste volume can be reduced to less than 10% of its original volume using the developed compactor. Waste compactors can serve urban hospitals where dumping space is a problem and the waste has to be transported. The compactor, developed by the University of Dar es Salaam team under the UNDP support, is capable of handling up to 25 kg of medical waste at a time and it is hydraulically operated. Furthermore, except for the hydraulic units and other electrical gadgets which can be bought as off-shelf parts, the designed waste compactor can be manufactured locally. The estimated total production cost was below USD 3,000. Part of UNDP requirements for this support was that the compactor design should be adopted by seven countries namely; Argentina, India, Latvia, Lebanon, Philippines, Senegal, Tanzania and Vietnam. These countries were nominated by UNDP to demonstrate the best techniques and practices of non-burn technologies in the developing countries.
ICT Adoption and Use in Tanzania SMEs
Authors: Msuya Cuthbet A. , Mjema Emmanuel A.M. , Kundi Beatus A.T.
Published: March 2021

The purpose of this paper was to establish the status of ICTs adoption and use in Tanzania SMEs. Previously, it was shown that there is a shortage of comprehensive, accurate and up to date data on many aspects of the SMEs sector including the level of ICT adoption and use. This has affected government efforts aimed at development of this important sector in the economic development of the country. Results show that: (i) By year 2014, adoption of ICTs in SMEs had grown from almost non-existence in year 2004 to 80.1% computer technology use, and over 56.6% for use of internet technologies; (ii) More than 53% of the SMEs were using ICTs as a strategic communication and marketing tool; (iii) 47% of the SMEs were competitive due to use of ICTs. Given these results, the government and key stakeholders can formulate more effective policies and incentives aimed at developing the SME sector. Further research is recommended to address post adoption competitiveness issues.
Handling of Syringe Sharps in A Non-Incineration Health Care Waste Disposal
Authors: Mwinuka Tito E. , Nyichomba Bravo B.
Published: March 2021

An attempt has been made by the R&D team of the University of Dar es Salaam todesign and manufacture two needle cutter prototypes, a manually operated and anautomatic needle cutter to be used in rural and urban areas, respectively. This is part ofthe UNDP and WHO efforts aimed at promoting the non-burn medical waste disposaltechnologies in developing countries such as Argentina, India, Latvia, Lebanon,Philippines, Senegal, Tanzania and Vietnam. The project also involves designing andmanufacturing of the autoclaves for sterilizing of needle cutters and other infectiousmedical waste. The use of needle cutters in hospitals is aimed at cutting the needles offfrom syringes hence eliminating the possibility of being re-used as may be the case ifthey are just buried in landfills. The needles and plastic barrels of the syringes are thensterilized at 121 o C in an autoclave before disposing them in land-fills or recycling them.It should be noted that unlike manual needle cutters, automatic needle cutters do not adda step in administering injection and hence they are likely to be accepted by nurses andhealth care authorities. Two types of automatic cutter prototypes were developed byUDSM R&D Team; one using pneumatic mechanisms and the other one using a 12V-DC motor to cut the syringe needles and to push the plastic barrel into the wastecontainer. Of the two, the 12V-DC motor operated mechanism was found to beaffordable and suitable for use in rural areas also since it can easily use solar power.The above prototypes have already been manufactured and tested and found to beworking properly. Views of various stakeholders were used to improve and perfect thedesigns. The costs of these prototypes are estimated to be USD 50 and 150 for manuallyoperated needle cutter and 12V-DC operated needle cutter, respectively. Thesetechnologies, except the automatic needle cutters, have already been disseminated tolocal producers so as to be able to manufacture the same in mass production and atmuch more affordable costs. Training on the use of non-burn technologies includingmanagement of medical waste is essential for successful implementation of thesetechnologies. There is a need also to sensitize the Government, Municipal Authoritiesand Healthcare Authorities including hospitals on non-burn disposal of medical wastefor the project to be successful.
Removal of orgRemoval of Organic Material in Free Water Surface Gravel Bed Filtersanic material in free water surface gravel bed filters
Authors: Mayo Aloyce W. , Ogombe Hesborne S.
Published: March 2021

The removal of organic material in free surface gravel bed filters was investigatedand modelled. Two pilot wetland units of 7.5m x 1.5m x 0.7m were constructedadjacent to the University of Dar es Salaam waste stabilization ponds to receivemaximum organic and hydraulic loading rates of less than 185 kg/ha/d and 110l/m 2 /d, respectively. These units received wastewater of domestic characteristicsfrom primary stabilization pond. The entire depth of 0.7 m of the wetland unitswere packed with gravel of size 8 ~ 25 mm and porosity of 35%. Samples werecollected from the influent and effluent of wetland units and were tested forchemical oxygen demand (COD), temperature, dissolved oxygen, pH and otherparameters useful for testing of the model. A semi-empirical model representingthe major processes taking place in the wetland units was developed byincorporating suspended biomass, biofilm biomass, and sedimentation andfiltration components. The model was optimized using computer program. Themodel was successfully developed and showed that biofilm of gravel mediacontributed significantly to COD removal in wetlands.
Moisture Induced Deformations in Glulam Members - Experiments and 3-D Finite Element Model
Authors: Kiwelu Henry M.
Published: March 2021

Experiments were performed on scaled glue laminated bending specimens to observetime dependent development of deformations during drying and wetting. Measurementsdetermined changes in the average moisture content and external shape and dimensionsbetween when specimens were placed into constant or variable climates. Alterations inthe external shape and dimensions reflected changes in the average value anddistribution of moisture and mechanosorptive creep in the glulam. The results are beingused to develop a sequentially-coupled three-dimensional hygrothermal Finite Element(FE) model for predicting temporally varying internal strains and external deformationsof drying or wetting solid wood structural components. The model implies temporallyvarying, and eventual steady, state internal stress distributions in members based onelastic and creep compliances that represent wood within glulam as a continuousorthotropic homogenised material. Thus, predictions are consistent with smearedengineering stress analysis methods rather than being a physically correct analogue ofhow solid wood behaves. This paper discusses limitations of and intended improvementsto the FE modelling. Complementary investigations are underway to address otheraspects of the hygrothermal behaviour of structural members of wood and othermaterials (e.g. reinforced concrete) embedded within superstructure frameworks ofmulti-storey hybrid buildings.
Hydrology and Hydraulics of the Lubigi Wetland in Uganda
Authors: Kayima John K. , Mayo Aloyce W. , Nobert Joel K.
Published: March 2021

The Lubigi wetland, which is located in the north-western part of Kampala, receives polluted water from Kampala city and discharges it into Mayanja River. However, there is lack of information and knowledge on the hydrology and hydraulics of the Lubigi wetland, which are important for protection of wetland ecosystems and fulfill the Uganda national policy for the conservation and management of wetland resources. The national policy aims at promoting the conservation of Uganda’s wetlands, in order to sustain their ecological and socio-economic functions for the present and future well- being of all the people of Uganda. Pertinent data collection, field tests and surveys were carried out to gather data necessary for establishing the current status of the hydraulics and hydrology of Lubigi wetland. The results revealed that the Lubigi wetland demonstrates considerable impounding reservoir and flood buffering capacity. This is an important service provided by the wetland, to alleviate possible negative impacts of storms and floods events. The Lubigi wetland total influents and effluents discharges, have mean values of 222,377.60±132,365 m3 /day and 221,356.80±122,256 m3 /d, respectively. The wetland water balance is dominated by the influent discharges which account for 93.21% of the total water influx, and the effluent discharges which account for 97.7% of the total water outflow. The wetland main study area hydraulic residence times, varies between 6.0 hours and 10 days. Hence, the wetland is endowed with abundant water fluxes, water impounding capacity and adequate hydraulic retention times. The volumetric efficiency of the wetland main study area is 63% and 38% during wet season and dry season, respectively. This indicates that on average only about 50% of the volume of the Lubigi wetland main study area is lost through short-circuiting. The dispersion number of the wetland was about 0.01 to 0.03, which indicates that the flow regime through wetland is close to plug flow.
Characteristics and Anaerobic Digestion of Fruits Wastes from Ubungo-Urafiki Market in Dar Es Salaam
Authors: Aloyce Edwir N. Richard , Mayo Aloyce W. , Kimwaga Richard J.
Published: March 2021

Fruits are susceptible to mechanical damages during their transfer to the markets if they are not packed well in containers. Hence fruits wastes are generated in large quantities and because of their organic nature they decompose, which leads to environmental problems. The objective of this research was to quantify and characterize the fruits wastes generated from the Ubungo Urafiki Market in Ubungo Municipality and to establish the potential treatment of these wastes by anaerobic digestion. The data were collected in the field to establish the characteristics quantity of wastes generated in order to determine the potential degradation of fruit wastes using anaerobic digestion process. The market receives seven main kinds of fruits including pineapples, mangoes, water melons, avocados, oranges; paw paws and ripe bananas, which generate about 4.85 tons of fruit wastes per day. The leading fruits with higher percentage of wastes were water melons and oranges, which generated about 800 kg/day and 797 kg/day, respectively. The results of batch plants experiments showed that the reactor with fruit waste-cattle manure-wood ash mixtures had a maximum biogas yield of 34.2 liters while the reactor with fruit wastes-mixtures had lowest biogas yields of 0.1 liters. The reactor with fruit waste- wood ash mixtures had high volatile solid and total solid removal efficiencies of 8.0% and 14.3%, respectively. For the maximization of biogas production wood ash was recommended in order to raise the pH value of the fruit wastes. The batch reactor used in this study was limiting pH control and therefore activities of methanogenic bacteria. It is recommended to adopt a semi continuous or continuous reactor in order to limit excessive production of organic acids, which are responsible for inhibition of biogas production.
Modelling Of Food Hazard Susceptibility in Komatipoort, South Africa
Authors: Khumalo Nomcebo , Mayo Aloyce W. , Munishi Subira
Published: March 2021

Komatipoort, a small town located at the confluence of Komati and Krokodil rivers, is constantly being hit by floods which affect the residents of this small town as well as the farmers settling along the rivers. This study aimed at mapping the flood hazard and susceptibility through the integration of GIS techniques and hydraulic modeling. Due to inconsistency in the length of streamflow data in the different gauging stations, a Hydrological modeling HBV model, was utilized for modelling runoff in order to extend flow records at station X2HO32 for Komati River. Calibration was conducted using observed data from 1982 to 1993, giving an efficiency value of 65% and validation was done using data from 1993 to 1999, giving an efficiency value of 53%. Flood frequencies were analyzed and flood quantiles were determined at different return periods. HEC-RAS was utilized to simulate the hydraulic parameters of Komati and Krokodil rivers to obtain flood hazard maps. GIS-based multi-criteria analysis techniques were incorporated for flood susceptibility mapping. Hydraulic analysis showed that the floods mostly affect the farms and settlements along the rivers and a small part of the central business district is affected. Flood susceptibility mapping showed that the area is generally highly susceptible to flooding because of a combination of anthropogenic and natural factors.
Modelling Transport of Heavy Metals in Geita Wetland along Mamubi River
Authors: Massawe Ezrael J. , Kimwaga Richard
Published: March 2021

The modelling of heavy metals in rivers is highly dependent on hydrodynamics, the transport of suspended particulate matter and the partition between dissolved and particulate phases. This paper presents the development of hydrodynamic model DUFLOW, which is a one dimensional flow and water quality simulation package, that describes the processes governing transformations and transport of heavy metals (Hg, Ni and Cu) along Mabubi River in the Geita wetland. Two monitoring stations were established along Mabubi River at the inlet (MBSP1) and outlet (MBSP2) of the wetland. A set of DUFLOW model inputs representative of the water conditions were collected from the established monitoring stations. The model was calibrated and validated for the prediction of flow and heavy metals (Hg, Ni, and Cu) transport, against a set of measured mean monthly monitoring data. Sensitive model parameters were adjusted within their feasible ranges during calibration to minimize model prediction errors. At the gauging station MBSP2, the calibration results showed the model predicted mean monthly flow within 17% of the measured mean monthly flow while the r2 coefficient and Nash-Sutcliffe (NSE) were 0.83 and 0.79 respectively. At the water quality monitoring station MBSP2, the calibration results showed the model predicted heavy metals (Hg, Ni and Cu) concentrations within 13% and 17% of their respective measured mean monthly concentrations. The mean monthly comparisons r 2 values for heavy metals ranged from 0.75 to 0.88 while the NSE values were between 0.70 and 0.82. The model results and field measurements demonstrated that about 40% of the annual heavy metals loadings which would otherwise reach the Lake Victoria are retained in the wetland. The Mabubi river model can therefore be used for prediction of heavy metals (Hg. Ni and Cu) transformation processes in the Geita wetland.
Modelling Transport of Nitrogen Compounds in Geita Wetland along Mtakuja River
Authors: Massawe Ezrael J. , Kimwaga Richard , Mwanuzi Fredrick
Published: March 2021

The impacts of excessive nitrogen loading to streams in a watershed occur in the receiving waters such as rivers at the outlet of the watershed. To quantify the impacts of land use and management practices on the nitrogen loading at the watershed outlet, simulation models are needed that can both predict the nitrogen loading at the edge of individual fields and predict the fate of nitrogen as it moves through the river network to the watershed outlet. This paper presents the results of a model analysis for describing the processes governing transformations and transport of nitrogen compounds (NO3-N and NH4-N) through Mtakuja River in the Geita wetland. The model was made in Soil and Water Assessment Tool (SWAT), a watershed model developed to assess the impact of land management practices on water, sediment and agricultural chemical yields with varying soils, land use and management conditions. Two monitoring stations namely MTSP1 and MTSP2 were established along Mtakuja River. A set of SWAT model inputs representative of the water conditions was collected from the established monitoring stations. The model was calibrated and validated for the prediction of flow and nitrogen compounds (NO3-N and NH4-N) transport, against a set of measured mean monthly monitoring data. Sensitive model parameters were adjusted within their feasible ranges during calibration to minimize model prediction errors. At the gauging station MTSP2, the calibration results showed that the model predicted mean monthly flow within 18% of the measured mean monthly flow with the r2 coefficient and Nash-Sutcliffe (NSE) were 0.84 and 0.82, respectively. At the water quality monitoring station MTSP2, the calibration results showed the model predicted nitrogen compounds (NO3-N and NH4-N) loadings within 21% and 23% of their respective measured mean monthly loadings. The mean monthly comparisons of r 2 values for nitrogen compounds ranged from 0.77 to 0.81 while the Nash-Sutcliffe Efficiency (NSE) values were between 0.72 and 0.73. The model results and field measurements demonstrated that about 70% of the annual nitrogen compounds loadings which would otherwise reach Lake Victoria are retained in the wetland. The Mtakuja river model can therefore be used for prediction of nitrogen compounds (NO3-N and NH4-N) transformation processes in the Geita wetland.
Analysis of Drought Using Meteorological and Microwave Remote Sensed Data: A Case of Wami Watershed, Tanzania
Authors: Juma Mwajuma , Mulungu Deogratias M.M.
Published: March 2021

Agricultural sector is important for the economy of Tanzania, but in recent years there is decline in its growth and performance because of persistent droughts. An in-depth study of droughts was conducted on Wami watershed through rainfall and satellite microwave remote sensing data leading for estimates of meteorological droughts and soil moisture based droughts, respectively. Rainfall data during 1973-2008 was used to obtain Drought Severity Index (DSI) and active imaging microwave radar data during 1997-2009 from ESA’s SAR missions of ENVISAT and ERS was used to obtain soil moisture anomalies (SMA). Soil map was used to explain discrepancies in droughts from SMA to DSI maps at intervals of time. Seasonality analysis and DSI results showed that the main sub-seasons contributing to rainy season are October through December, January-February and March through May, and drought years were 1984, 1991, 1994, 2004 and 2006. Results showed that the last decade (2000s) had severe droughts that covered 35-39% of the Wami watershed and could have affected 1128000 people. The soil moisture based drought maps showed the same drought conditions as DSI maps in January, March, May and October. This indicated that in most areas the meteorological droughts can be used to infer to droughts conditions in the soil during the rainy season. The obtained drought events and impacts were confirmed in the field through interviews. However, in July SMA map showed normal and wet conditions whereas it was a dry season for DSI map. This showed that when rainy season ends, the soil still holds some moisture, which can be available for simple crops like vegetables. Therefore, it can be concluded that the SMA was able to provide a better alternative to DSI especially for increased spatial coverage and accuracy of drought monitoring for agricultural production. The SMA enables to map droughts conditions at any point spatially rather than point based DSI maps, which may be prone to rainfall data gaps and spatial interpolation errors. The SMA approach for drought monitoring may be useful to rainfall data scarcity areas of Tanzania and for agricultural droughts risk management.
Low Voltage Ride through Enhancement for Wind Turbines Equipped With DFIG under Symmetrical Grid Faults
Authors: Justo Jackson J. , Mwasilu Francis A.
Published: March 2021

In modern power systems with significant penetration of wind-turbines (WTs), improvement of low voltage ride through (LVRT) capability of WTs equipped with doubly-fed induction generators (DFIGs) is an important issue. Thus, this paper proposes a low voltage ride through (LVRT) strategy, which comprise of a capacitor connected in series with an inductor both connected in parallel to a resistor. The configuration is then connected to a small series resistor via a pair of antiparallel-Thyristors. The circuit and its switching control scheme of the proposed LVRT circuit are designed to: minimize the transition times, maintain the RSC connection to the rotor-windings, and reduce oscillations of dc-link voltage. In this case, the capacitor is entitled to eliminate ripples generated in the rotor voltage while the inductor reduces the ripple in rotor current. Different fault conditions were studied to validate the performance of the proposed scheme using MATLAB/Simulink platform. Comparative results and analysis are presented with conventional LVRT strategies.
The Fate of Nitrogen and Faecal Coliform in the Lubigi Wetland in Uganda
Authors: Kayima John K. , Mayo Aloyce W. , Nobert Joel K.
Published: March 2021

The capacity of the Lubigi wetland to reduce nitrogen and faecal coliform pollution entering Lake Kyoga in Uganda was investigated. Three transects with 5 sampling points in each, were established in the wetland. Wetland plants samples were collected from the specific locations along the transects, and laboratory tests and analyses were carried out for plants biomass and nitrogen contents determination. Samples of wetland sediments were also collected, and laboratory tests and analyses were done for determination of nitrogen content in the sediments. Wetland water samples were taken from the main wetland inlet and the main outlet from the wetland main study area. At the same time, wetland water pH, dissolved oxygen and temperatures were measured in-situ. Laboratory tests and analyses for ammonia-nitrogen, nitrate-nitrogen, total Kjeldahl nitrogen, total nitrogen and faecal coliforms were carried out on the wetland water samples. The results indicate that the Lubigi wetland received about 16 to 173 mg/l of total nitrogen, largely in form of organic- nitrogen (64.7%) and ammonia-nitrogen (35.2%). Nitrate-nitrogen and Nitrite-nitrite accounted for only 0.1% of the total nitrogen in the inlet. The wetland removed about 24.9% of this nitrogen, which is equivalent to removal of about 1,672 tons of nitrogen annually. About 67.5 gN/m2 and 0.30 gN/kg of dry sediments were sequestered in the wetland plants biomass and the benthic layer respectively. The Lubigi wetland main study area also receives faecal coliform concentrations with the wetland inlet mean value of 653,509 CFU/100ml and its outlet mean value is 218,676 CFU/100ml. These values give a faecal coliform (FC) overall removal efficiency of approximately 66.5%. It was thus concluded that the Lubigi wetland has considerable capacity to buffer and protect Lake Kyoga, by reducing nitrogen and faecal coliform pollution entering the lake.
The Comparative Analysis of the Performances of Four and Six Pole Pairs Permanent Magnet Synchronous Generator
Authors: Msuya R.A. , Kainkwa R.R.M. , Mgwatu M.I
Published: March 2021

Wind power applications using multi-poles permanent magnet generators have become very attractive especially in small ratings. Low-speed multi-pole PM generators are maintenance-free and may be used in different climate conditions. Most of the low speed wind turbine generators presented is permanent magnet machines, which have advantages of high efficiency and reliability since there is no need of external excitation and conductor losses are removed from the rotor. From the study two types of PM AC generator are designed with 6 pole pairs and the other one with 4 pole pairs. These generators were designed and analysed using Maxwell software. The results were compared for the best performance determination. The 6 poles generator was found to have good power output with less Total Harmonic Distortion (THD) and high efficiency of over 92% that could be achieved at low wind speed of 2 m/s.
Nonlinear Direct Torque Control of Interior Permanent Magnet Synchronous Motor Drive
Authors: Justo Jackson J. , Mwasilu Francis
Published: March 2021

This paper presents a nonlinear direct torque control (NDTC) strategy of interior permanent magnet synchronous motors (IPMSMs) for electric vehicle (EV) propulsion. The proposed NDTC scheme applies a nonlinear model of IPMSM to dynamically determine the optimal switching states that optimize the EV drivers’ decision to reduce the workload. Moreover, the proposed NDTC method has a simple control structure and can explicitly handle system constraints and nonlinearities. The performance evaluation is conducted via a prototype IPMSM test-bed with a TMS320F28335 DSP. Comparative experimental results provide the evidence of improvements of the proposed NDTC strategy over the conventional DTC strategy by indicating a fast torque response and an accurate speed tracking even under rapid speed change conditions.