bluuebunny/crossref_metadata_2025 huggingface dataset:
Modelling of Agricultural Non-point Sources Pollutants in Upper Pangani River Basin (UPRB), Tanzania
Authors: Fredrick Mwanuzi
Published: March 2021

The Upper Pangani River and its watershed are increasingly being impacted by environmental problems which includenon point source pollutants that are threatening the watershed resources. Increased human activities due to populationincrease, and hence agricultural activities, livestock development, the use of agrochemicals and other land developmentin the basin, have tended to lead to a serious pollution of the river water which also affects not only the aquatic life butalso human health.With intensive and extensive modern agriculture in which artificial fertilizers are in frequent use, there is a highprobability to find chemicals easily flowing into water, thus polluting it. The introduction of agricultural chemicals inrivers may be detrimental. Nitrogen and Phosphorus which are present in agricultural chemicals are essential plantnutrients, which when introduced into surface waters may cause some health problems such as blue-baby syndrome andstomach cancer.To carry out this study we divided the Upper Pangani River basin into two sub-basins; Kikuletwa and Ruvu. The studyconcentrated on Ruvu sub-basin to study and model the pollution transported to the rivers. QUAL2E model was chosenand applied to assess the pollution status of the river network. The model simulated stream flow, dissolved oxygen,phosphorus and nitrogen compounds. From model results, the amount of non-point source load reaching Ruvu river wasfound to be 7857.81tons/yr for nitrogen and 12057.39 tons/yr for phosphorus. The results of the QUAL2E model suggestthat there is pollution at upstream rivers as a result of application of fertilizers to the irrigation schemes which are themain sources of non point source pollution.
Use of Simplified Mathematical Formulations in Multi-phase Thermal Pump (MPTP) for Theoretical Prediction of Working Conditions
Authors: Chami Francis A.
Published: March 2021

In this work mathematical expressions have been formed and solved to get predictions of working parameters of multiphase thermal pump (MPTP). MPTP is a simple pump which uses steam to pump water. The results have been comparedwith data found experimentally. Experimental and theoretical values for a range of pressures versus velocity differed byapproximately 8.7% up 12% Through dimensional analysis dimensionless parameters were found Re, Eu, Fo and h/d pmp .These helped to further elucidate the pump’s pumping phenomenon. It was experimentally shown that the Reynoldsnumber found theoretically gave limit of flow operating regime of the pump that it is in the transition regime. Above thisthe pump failed to operate. The Euler dimensionless number gave the dependency of interface velocity on pressurerelation, when pressure was raised the velocity increased. The relation between the two parameters was found to beapproximately quadratic. The Fourier dimensionless number gave the influence of heat transfer properties of thematerial of the pump to the operating characteristics. It was experimentally found that the influence of the overall heattransfer coefficient and heat transfer were the main driving forces behind the operation of the pump. Average interfacevelocities in the pump were found using pipe flow energy and mass conservation equations. Conditions for operation(pumping and suction) of the pump have been established based on the formed mathematical formulations.
Study of Nutrient Pollutants and Their Impacts on the Water Quality of the Mindu Reservoir at Morogoro Municipality
Authors: Ngonyani Consolatha J. , Nkotagu Hudson H.
Published: March 2021

The physical-chemical parameters characterization of Mindu Reservoir, whose 50% of its waters is being plagued byaquatic weeds, involved the analyses of water and sediment samples that were collected during the dry season. As thenutrients levels of Mindu waters were determined, phosphorous (TP - PO 43- ) levels were found to be high enough forsupporting eutrophication process. Likewise Nitrogen/Phosphorous ratios average of 8.51 ± 4.32 suggested a Redfieldbehavior of nutrients with nitrogen being a limiting one. The dominant clay minerals of the Mindu surficial sedimentswere found to be kaolin and illite, where as the Cation Exchange Capacity values were found to be high enough for thesorption of nutrients and pollutants. Both river inflows, overlay-flows and sediments forms the mode of transport ofnutrient, with the later behaving as sinks of nutrients through out the year. The evaporation, bio-geo-chemical andNitrogen fixation processes along with macrophyte productivity, support the hypotheses that physical-bio-geo-chemicalprocesses influences the spatial distribution of major ion in the Mindu Reservoir. These findings classify Mindu aseutrophic, calcium magnesium bicarbonate type. A detailed multidisciplinary study that involves more than one yearcycle was recommended, to capture inter seasonal variability, and for the modeling of the sequestration of nutrients invarious trophic levels.
Assessment of Integrated Water Resources Management Practice in Yatta Canal, Machakos District, Kenya
Authors: Simitu Lawrence N. , Odira Patts M.A.
Published: March 2021

Yatta Canal is situated in Yatta division, Machakos district about 100 km from Nairobi along Thika- Garissa road. It is about 60 Km long and supplies water for domestic, livestock and irrigation use. Over the years, the water supply has been unreliable especially during dry season leading to conflicts between upstream and downstream consumers. Sometimes the Government has been forced to intervene to restore order. The study aimed at assessing the use of Yatta canal, based on the principles of Integrated Water Resources Management (IWRM) which stipulates efficient use of water and involvement of all stakeholders in decision making for sustainability. Based on this concept, it was established that the current water demand outstrips supply and that there is inefficient water use especially for irrigation. Waterallocation process favours landowners, and stakeholders are not fully involved in planning, management and development. Further, women’s participation in decision-making is minimal. There is no environmental voice during water allocation and thus the reserve/ base flow in the canal has not been maintained. This means that IWRM concept has not been practiced and this has resulted to conflict among various water users. As Yatta canal gets water from Thika river, there is need to establish Thika river basin water users association where stakeholders can influence decisions on water allocation and management. This will create a forum to discuss efficient water use at all levels and promote internal policing to ensure fair allocation, thus minimizing conflicts and promoting the IWRM concept.
The Limnogeology of the Lakes Sagara and Nyamagoma
Authors: Nkotagu H.H. , Athuman C.B.
Published: March 2021

The present study focuses on the limnogeological aspects of the lakes Sagara and Nyamagoma within the Malagarasi Wetland Ecosystem. Abiotic parameters from water and sediment samples were determined during the dry and wet seasons using appropriate gears and methods. The data show variation of the abiotic parameters in both lakes from thewater surface to the bottom. Lake Nyamagoma is less turbid (0.7-24 NTU) than Lake Sagara (25 to 65 NTU). The water transparency was also high at Lake Nyamagoma (0.75-1.5 m) thus supporting the observed turbidity trend. The physical chemical changes may be attributed to processes such as cooling, dissociation, dissolution, decomposition, adsorption, precipitation, cation exchange and photosynthesis. However, higher nutrient concentration was observed in the wet season than dry season with the exception of SiO 2 consequent to dilution effect by surface runoff. The mineralogical content (Kaolinite, Smectite, Illite and Quartz) of the lake sediments indicate existence of good drainage conditions at the lakes as supported by the geology of the area. It is recommended that a long-term limnogeological monitoring andevaluation be conducted so as to understand future nutrient hydrodynamics and hydrological functioning of the wetland ecosystem.
Strategies for Promoting the Use of Concrete Pavements in Tanzania: Technical and Institutional Considerations
Authors: Mfinanga D.A. , Bwire H.
Published: March 2021

High-type roads in Tanzania have been predominantly of asphaltic concrete construction. This ever enlarging and ageing asphaltic road network represents increasing resource requirements on the road agency in the form of maintenance. Limited resources coupled with the ever sky-rocketing costs of petroleum products and the competing demands of social economic developments, presupposes the need to look for alternative road construction technology that is more cost-effective and resource optimising. Experience gained from developed and some developing countries where concrete pavements have been widely used suggests the potential of this type of pavement in many developingcountries. This paper discusses the technical aspects of design and construction- and maintenance-related aspects of concrete pavements. The discussion extends further to highlight issues pertaining to the performance of concrete pavements and strategies for promoting the use of concrete pavements in Tanzania. Conclusions and recommendationsare made with suggestions on how to start implementing the proposed strategies.
Sediment Yield Prediction in Tanzania:Case study of Dodoma District Catchments
Authors: Mulemgera Mathew K.
Published: March 2021

Soil erosion and sedimentation is serious and is resulting in rapid sedimentation of streams and reservoirs in Tanzania. This makes sediment yield modeling important before undertaking water resources development projects, although it has so far not been done in the country. At present sediment yield prediction can be done using physically based models,empirical soil erosion and sediment yield models, and sediment rating curves. The physically based models contain numerous parameters that are difficult to measure or estimate, making them inappropriate in developing countries like Tanzania. The rating curves give rough estimates while the empirical sediment yield models need runoff data that is notavailable in Tanzania. The revised USLE parametric (empirical) model that had been tested and found to be suitable for soil erosion prediction was selected for sediment yield prediction study reported in this paper. The testing of the model has shown to give acceptable results. For sediment measurements ranging from about 7 t/ha.year to 11 t/ha.year, the model predicted sediments yields ranging from about 6 t/ha.year to 12 t/ha.year, withcoefficent of determination (R 2 ) equal to about 0.53. Since soil erosion and sedimentation of water resources are serious problems in Tanzania, sediment yield modeling using the RUSLE can be a very useful tool in the country when used.
Sedimentation Status of Lake Victoria: Loading from River Mouth and In-lake Sedimentation
Authors: Mwanuzi F. , Rutagemwa D.K. , Mathayo A.
Published: March 2021

Lake sediments consist of the input of suspended solids by river discharges, the autochthonous produced particulate matter in the water column and the settled material on the lake bottom. The loading, transport, formation and decay of the sediments entering the Lake Victoria from Tanzanian side was monitored for the period 2000 to 2005. The sedimentation study focused on; quantification of settling fluxes of particulate nutrients and organic carbon at the off-shore(Pelagic) and near-shore(Littoral) monitoring stations. Monitored data on sedimentation rate and settling velocities has been sampled and analysed in the period November 2000 to March 2005. The mean sedimentation rate at littoral stations for total particulate phosphorous (TPP) was about twice as compared to pelagic stations. The same situation was observed for total particulate carbon (TPC), however, total particulate silica did not show a clear pattern of variability between littoral and pelagic stations though there was a general tendency of decreasing towards the pelagic stations. Mean value for TPC /TPP sedimentation rate ratio was 117.61 for littoral and 90.74 for pelagic stations respectively compared to TBSi/TPP which was 3.15 for littoral and 2.10 for pelagic stations. The results show that sedimentation rates are highest at the littoral stations compared to pelagic stations. The differences in settling velocities indicate that the settling material consists dead and living material with a contribution of diatoms. The stoichiometriccomposition of the settling material indicates nitrogen limitation and a non-dominance of diatoms.
Improving the Availability of Manufacturability Information through Decentralization of Process Planning
Authors: Opiyo Eliab Z
Published: March 2021

Process planning is part of the general product development and production process that usually follows design and precedes manufacturing. Manufacturability and process planning information in general play central role in many product development and production activities, including paradoxically, conceptual and detail design - the activities that take place before process planning. The need of conducting some of the process planning activities formally before or during design is thus rather obvious. One of the main research issues is therefore the identification of the process planning activities that can be performed before the traditional process planning phase and handling of the process planning information so as to adequately provide the designers with the manufacturability informationneeded during conceptual and detail design. Another issue is how to support collaboration during process planning and how to maintain continuity of the process planning tasks. This paper suggests the decentralization of the process planning task and proposes the execution of the process planning activities in a piecemeal fashion, starting right afterreceiving an order and specifying the requirements for a product. Process planning under the proposed procedure consists of six semi-autonomous sub-phases, some of which comprise activities that must be conducted prior to the process planning phase. This helps to overcome the problem of timely availability of manufacturability information during the execution of upstream and downstream product development and production activities. The paper alsoproposes a computer-based method of handling the manufacturability information generated in various stages of the product development and production process. A database design and structure of prototype software that manages the process planning information are presented and discussed. Furthermore, a case study conducted to explore howthe proposed process planning procedure could be put in use is presented and discussed.
Modeling of a Spray Assisted Natural Draft Cooling Tower
Authors: Kaunde O.K.
Published: March 2021

Cooling towers are one of the largest heat and mass transfer devices that are in common use. A novel type of cooling tower has been proposed in which air flow rate into the tower is drawn by ejector action of sprays instead of fans as is done in conventional mechanical forced or induced draft cooling towers. This novel design offers the potential of savingthe energy cost for driving the fan. The paper presents mathematical models for momentum transfer which is the driving force causing the entrainment of air. Also the heat transfer model for co-current flow of liquid and gas in the tower has been presented. The liquid to gas ratio tend to decrease as liquid rate increases. The ratio attained in the experimentallaboratory tower was 3.3, correspondingly the Momentum transfer efficiency for the tower was 60% and was the highest. Experiments for cooling water initially at 45 o C to final water temperature 27 o C showed that the cooling tower efficiency was 54% and number of transfer unit 0.8.
Development of a Genetic Algorithm Based Search Strategy Suited For Design Optimisation of Internal Combustion Engines
Authors: Nalitolela N.G , Kadete H.
Published: March 2021

Engine design optimisation is a multi-objective, multi-domain problem in a discontinuous design space. The state of the art of optimisation techniques shows that only methods of direct and adaptive search are appropriate for this type of problem. These include, adaptive random search, simulated annealing, evolution strategies and genetic algorithms. Ofthese methods, the genetic algorithms have been shown to be the most suited for the optimisation of multi-modal response functions in a discontinuous design space. This paper considers the important characteristics of genetic algorithms and their adaptation for use in parametric design optimisation of internal combustion engines. In order to verify the basicfunctionality of the proposed optimisation strategy, a genetic algorithm based, optimisation software was developed and tested on a number of analytical functions, selected from optimisation literature, with satisfactory results.
Open Source Software in Health Information Systems: Opportunities and Challenges
Authors: Twaakyondo Hashim M. , Lungo Juma H.
Published: March 2021

The paper presents results of a study seeking to identify constraining and motivating factors associated with the adoption and use of Free Open Source Software to computerise health Information Systems in a developing country. The study approach is interpretive research to case study with a triangulation of several qualitative data collection methods such as interviews, group discussions and document analysis. The findings indicate that using open source software has advantages and disadvantages. The advantages are low entry cost to adopting software, possibilities of software localization, avoiding being hostage of proprietary software and foster knowledge acquisition among software developers. The disadvantages are the need for constant internet access, high switching costs, and lack of human resources especially IT professionals to maintain the software since users get more rights in using and maintaining the system. The study concludes that because of the dynamics in health information systems, open source is appropriate.
Investigation of the Effect of Particle Size on Groundnut-Oil Solvent Extraction
Authors: Manyele S.V. , Kahemel I.F.
Published: March 2021

An investigation of the effect of particle size on the performance of vegetable oil recovery by solvent extraction is reported. Experiments were conducted using soxhlet extractor, groundnuts and n-hexane. Samples were grouped into mean particle sizes of 0.25, 0.75, 1.3, 3.3, and 7.5 mm using standard sieves. The effect of particle size was studied for extraction time intervals of 1, 2, 3, 4, 5 and 8 hours. The oil yield, oil recovered per kg solvent used, kg solvent lost per unit time, and the rate of extraction (kg oil recovered per hour) decreased with increasing particle size. Meanwhile, the percent of solvent recovered, the ratio of oilrecovered to the total volatile matter driven off and the kg solvent lost per kg oil recovered, increased with increasing particle size. Based on the normalization of averaged extraction-parameters, a mean particle size of 3.3 mm was observed to be the optimum size.
Improving the Design of Low Volume Sealed Roads in Tanzania
Authors: Mfinanga David A. , Mwakyami Lusekelo A.
Published: March 2021

The main objective of the study was to identify appropriate road designs for Low Volume Sealed Roads (LVSRs) with the aim of improving the design of such roads in Tanzania. The study was conducted in Dar es Salaam and Morogoro regions in Tanzania where data for LVSRs were collected from primary and secondary sources in the two regions. The study found that by using an improved pavement design method specifically meant for LVSRs results in cost savings for LVSRs of up to 51% compared with the conventional method of pavement design in Tanzania. The study recommends that the pavement design method for lightly trafficked sealed roads in southern Africa developed by Transport Research Laboratory, which was found to be most cost-effective, be used to design (or develop a procedure for design of) LVSRs in Tanzania and that the roads be preferably sealed with Otta seal or Surface dressing. The study also recommends that LVSRs in Tanzania be defined by a maximum traffic volume of 400 vpd.
Integrated Remote Sensing and Gas Techniques for Groundwater Exploration in Semi-Arid Region: A Case of Karamoja Region – Uganda
Authors: Lubang B. , Nobert J. , Mtalo E.G.
Published: March 2021

Groundwater is a precious resource that covers wide geographical extent. Proper evaluation is required in order to ensure prudent use of groundwater resources. The current groundwater assessment in Karamoja region, as in many parts of the world, uses Apparent Resistivity and Vertical Electrical Sounding, which has limited coverage to some localized usually predetermined areas. Comprehensive groundwater development program needs a wide area coverage and large volume of multidisciplinary data.In the present study, an integrated remote sensing and GIS based methodology is developed and tested for the evaluation of groundwater resources of Karamoja Sub Region, Northeastern Uganda. The components of the study are delineation of the groundwater potential zones in the area and evaluation of the relationship between delineated groundwater potential zones and aquifer characteristics.The groundwater potential zones are determined by the relevant layers, which include hydro-geomorphology, lineament density, slope, drainage density, overburden thickness and aquifer depth, rainfall, geology, land use, and soil were integrated in Arc/Info grid environment. Weighted index overlay method developed by Multi Criteria Analysis (Analytical Hierarchy Process) was used to assign weights to the different map layers. All the information layers were been integrated through GIS analysis, employing the use of Natural Break (Jenks) method for classification. Alexandru groundwater potential zoning using the Transmissivity values was used for the final classification of the potential zones and correlation with ground-truth data. Over 70% correlation was achieved showing the significance of GIS in groundwater mapping.
Identification of Unbalanced Forces and Foundation Parameters of Rotating Machines from Vibration Measurements
Authors: Nalitoela N.G.
Published: March 2021

A technique is described to use measured vibration data of a rotating machine and its foundation to identify unbalanced forces, stiffness and damping parameters of the mountings, and the parameters of the foundation. It is based on an idealisation treating the rotor, the machine structure and the foundation as rigid masses supported by springs and dampers. Operational vibration data of the machine and its foundation before andafter the rotating unbalanced forces are perturbed by adding unbalanced mass to the rotor are used in the identification procedure. Once the parameters are identified, dynamic forces transmitted to the foundation can be estimated. The technique is demonstrated using simulated example for a machine with a two bearings rotor.
Pedestrians’ Crossing Problems at the Manzese Footbridge and Proposed Measures
Authors: Shariff Ali A. , Tamba Saidi A. , Mdimi Azizi A.
Published: March 2021

In its efforts to restore safety to pedestrians the Government of Tanzania constructed the Manzese Footbridge along the Morogoro road. The project cost was TShs. 46,300 Million at the price in year 1990. The bridge design was carried out in accordance with Road Bridge Design Manual published by Japan Road Association. Unfortunately, only one pedestrian bridge has been built in Dar es Salaam since 1991. Footbridges and underpasses have hundred percent potential of protecting the pedestrian’s safety when the traffic streambeing crossed is heavy. It is not known why this advantage is not fully utilized by pedestrians in Dar es Salaam city. The paper tries to find out the reasons behind this trend. A case study of the footbridge at Manzese and two neighbouring zebra crossings one on either side of thebridge were used. Experimental data of the number of pedestrians crossing at the bridge, Tip Top and Bakhresa zebra crossings at fifteen minute intervals were collected for five working days starting from 1200 to 1515hours. The average deviations of pedestrians crossing at Tip Top and Bakhresa from the bridge were analysed by means of a paired t-statistic to uncover the usage inadequacy of the crossing facilities. Manzese foot bridge quality was also analysed by the Five Point Likert Scale using five quality attribute sentences. A random sample of 165 people was used in the analysis. The t-statistic showed that the bridge crossing is not significant at 5% level but significant at Tip Top and Bakhresa zebra crossings. This reveals that the pedestrians are not using the bridge compared with the other two zebra crossings. The Likert method showed that inadequate security, loss of muscle energy, no plaza,dizziness and no facilities to attract crossing of all types of pedestrians are reasons hindering its use. It is recommended that the above findings can be rectified by providing security lighting, police patrol and modification of bridge structure.
Characterisation of a Mobile Jaw Crusher for Small Scale Mining and Construction Industry
Authors: Itika A.J.M.
Published: March 2021

A small jaw crusher with a crushing capacity of 1 ton per hour has been developed for use in the small scale mining and construction industry. A 3.68 kW air cooled diesel engine was installed to power the crusher. Laboratory and field test were conducted using limestone as feed material at different operating parameters. The analysis of the product from the crusher showed that at a constant jaw gap, coarser products were obtained when the rotary speed was varied from 220 rpm to 300 rpm. With a jaw gap of 25 mm, a higher cumulative undersize fraction was obtained at particle size 25 mm. In contrast, at a jaw gap of 15 mm, highercumulative undersize fraction was obtained at particle size 15 mm. With a feed size 80% passing 60 mm, a finer product was obtained as compared to a feed 80% passing 120 mm. The throughput of the machine increased from 0.4 ton/hr to 0.7 ton/hr when the speed was increased from 220 rpm to 300 rpm. It was found that it is possible to select a combination of operating parameters to achieve a particular goal of operation.
The Effect of Rotation and Temperature on the Inhibition Performance of Cashew (Anacardium Occidentale L.) Nut Shell Liquid on Co2 Corrosion of Carbon Steel
Authors: Buchweishaija J. , Mkayala L.L.
Published: March 2021

A natural extract of cashew nut shells, Cashew Nut Shell Liquid (CNSL) was investigated as a corrosion inhibitor for carbon steel in 3% NaCl solutions saturated with CO2 gas using electrochemical techniques (i.e. potentiodynamic polarization and ac-impedance). The investigation was performed at different temperatures under static and dynamic conditions using a Rotating Disk Electrode (RDE). It was found that CNSL reduces the electrochemical processes taking place on carbon steel undergoing corrosion. The percentage inhibitorefficiency increases with increase in CNSL concentration and decreases with rise in temperature. Better performance at low CNSL concentration was registered under dynamic conditions and room temperatures. Thus CNSL is a potential corrosion inhibitor for carbon steel undergoing corrosion in CO2 medium.
The “Tea Cup Effect” and Removal of Suspended Solids from Water
Authors: MASHAURI D.A.
Published: March 2021

Suspended solids problem in water is an issue as old as water treatment itself. Suspended solids can be causativeto eroding through abrasion of impellers, pump casings, pipes and other water works related appurtenances.It is therefore appropriate that suspended solids must be removed as early as possible in the water workstreatment facilities. It is usually done at the river/lake intakes to reduce the coarse particulate matter thatwould otherwise adversely affect the water works thereafter. The fine particles that will escape the entrapmentat the intake works would therefore require further and more effective system that would remove this fraction.By and large this removal process is achieved by chemically aided process such as coagulation/flocculationunit operation. This process is expensive and demands high level trained personnel to man them. In the samevein then a simple and effective system is proposed. This is a swirl or grit removal system that does not needany chemicals, moving parts or even highly trained personnel to operate them. This paper is looking at thetheory of the “Tea Cup Effect” and how it has been used in practice to remove or reduce suspended solids fromwater. The paper gives some examples where such devices have been used and how effective they have been.
Oxygen Production Technologies for Oxy
Authors: Katalambula H.
Published: March 2021

Carbon dioxide, a dominating contributor to global warming is emitted to the atmosphere from power plantsduring combustion of coal. Oxy-fuel combustion is a new technology leading to a simplified sequestrationof CO2. In this technology, fossil fuel is combusted with oxygen (instead of air) in such a way that the fluegas primarily consists of CO2, which can then be sequestered without significant processing. Part of the fluegas is used to dilute the oxygen in order to maintain the temperatures in the combustion process. The mainenergy penalty in oxy-fuel combustion is the cost of oxygen production. There are three major processes forair separation to produce oxygen, these are: cryogenic distillation, membrane separation and gas adsorption.Cryogenic distillation is well established process for large scale production but high energy consumption isthe main disadvantage of this process. Membrane and adsorption processes are common for small and mediumscale production. In gas adsorption, there are air separation techniques such as pressure and temperatureswing methods. The production of oxygen with 90-95% purity and 5000+tpd production is the main challengefor this technology. At present the technology that can supply oxygen in large quantity is the cryogenicseparation of oxygen from air. The papers aims at presenting a comprehensive review of the air separationtechnologies and identify areas that need attention so that oxy-firing can be achieved. The paper thereforelooks at different technologies used for oxygen production, economic concepts as well as integration issues inthe existing plants.
An Equation for Estimating the (R) Use Slope Steepness Factor, s
Authors: Katalambula H.
Published: March 2021

Currently three equations are used for calculating slope steepness factor for the revised universal soil lossequation (RUSLE); one for slopes less than nine percent, the second for slopes equal or greater than ninepercent, and the third equation that has been proposed for use in China for slopes equal or greater than 17%. The three equations have linear relationships between slope steepness factor, S and the sine of the slopeangle, q. The three equations under predict the factor, S when used on slope steepness beyond the data setsused to develop them. In addressing this problem several alternative forms of equations (linear, power, andpolynomial) were tested using field plot soil loss data gathered by several researchers in different countriesfor slopes ranging from three percent to 55 %. A single power function relating the sine of the slope angle, qto the slope steepness factor, S has been identified to be more suitable and accurate for estimating the RUSLEslope steepness factor, S.
Auditing of Traffic Signs and Road Markings in Dar es Salaam City
Authors: Bwire Hanniabl , Mnkeni Joseph K.
Published: March 2021

This study examines the efficacy of the traffic signs and road markings in Dar es Salaam City. The studyfocuses on the availability and conditions of traffic signs and road markings in some selected roads in the city.Auditing of traffic signs and road markings is carried out as one of the means of promoting road safety andimproving road capacity in the city. The auditing procedure involved field studies through the use of trafficsigns/markings checklists and ranking of road stretches according to the availability and conditions of trafficsigns observed for improvement prioritization in case of financial constraints. In ranking the road sections in accordance to the overall conditions and availability of traffic signs, an index was developed. The index considered six factors of traffic signs availability and conditions that were observed in the field; (i) availability (ii)  orrectness of size (iii) visibility of signs (iv) physical condition (v) correct placement and (vi) the need of sign protection. It is recommended that the responsible agency and Municipal councils carry out auditing f traffic signs/markings and identify deficiencies in signage and road markings and plan for improvement accordingly. In case of financial constraints, the developed performance index may be used to rank roads/road sections for improvement priority.
Modelling of Coal Slag flow and Layer Thickness in a High Temperature Entrained Flow Gasifier
Authors: Katalambula H.
Published: March 2021

A 2-D model for the slag flow simulation in an entrained flow gasifier has been developed. In addition tomass, momentum and energy conservation equations, volume of fluid (VOF) equation was solved to track theliquid-gas interface. Liquid phase consists of melted coal ash particles which deposits on the wall and movedownward. The gasification reaction is not considered here but it is postulated to have a mass flow throughthe interface towards the mass of the liquid phase. The reactor walls are usually kept cold so a temperaturegradient and then a solid layer form within the slag layer. The solidification and its effect on the slag layerthickness are also considered here. Results show that, depending on the ash composition which determines thefluid’s rheological properties, the solid phase constitutes a large part of the slag layer
The Influence of Branches in The Performance of Power-line Communication Systems that Use Mc-Coma with Reed Solomon Coding
Authors: Felix Emmanuel , Anatory Justinian , Kissaka Mussa M.
Published: March 2021

Power-line network is proposed as an infrastructure for Information and Communications Technologies (ICTs)services provision. However, there are a number of factors that contribute greatly to power-line communication performance degradation. These include number of branches that can be added or removed from the power- line network, lengths of the branch lines, loading etc. It has been pointed out that the number of branches is one of the factors that affects power-line performance to a certain extent. In this paper the influence of number of branches on the performance of Broadband Power-line communication (BPLC) that uses MC- CDMA modulation scheme with Reed Solomon coding is investigated. It is shown that with substantial number of branches at a particular node in power-line a performance BER of 10-6 at SNR of about 25dB with channel capacity of 300Mb/s can be attained
Case Studies: In-Situ Rebuilding of Damaged Rope Drum Shafts of SSG Crane and the Repair of Circumferential Crack of Cement Kiln by Welding.
Authors: Runyoro Joseph
Published: March 2021

Material failures in engineering are characterized by unwanted downtime of equipment and require the application of sound engineering principles to rectify the problem so that it does not reoccur. The most widely method for repairing damaged steel structures such as rope drum shaft or cracked cement kiln is by Manual metal arc welding. The equipment mentioned have their main importance that, when they are broken down, they cost a lot of money in lost revenue and affects a lot of people in terms of business and livelihood. The nominal diameter (DN) 240 rope drum shaft was damaged when the roller bearing failed and abraded the shaftbearing journal in such a way that the diameter decreased. The solution was either to order the new shaft, or repair the existing shaft in workshops with lathe machines capable of accommodating it. Ordering the new one will have taken a long time to deliver. Installation process would have been costly taking into consideration the position of the hoist drum being at a height of over 40 meters above the ground, and no crane was available in the country with required capacity. The remaining and immediate solution was to repair the damaged bearing journal in-situ. The paper describes how the repair was carried out successfully, and has been in operation since 1995. Recently, another failure of the same nature occurred on another equipment in which the same assistance were sought. In 1994, the cement kiln was found to have a 270 mm length circumferential crack on a 65 mm thick plate which needed urgent repair so that the production of cement can proceed while waiting for replacement. The immediate repair was necessary to avoid the bending of the kiln which would have caused uneven rotation and poor sealing of refractory bricks. The crack was on the cantilever section of the kiln which, if the crack was allowed to grow, would have caused the section with cooler tubes to snap off. The paper explains how the repair was carried out allowing the plant to operate for two years before segmentreplacement.
Modelling the Impact of Urbanization on Groundwater Using System Dynamic Technique. A Case Study of Arusha Municipal Well Field in Northeastern Tanzania.
Authors: Kashimbiri Nimzihirwa , Mtalo Felix , Mwanuzi Fredrick , Mandal Nepal C. , Singh Vijay S.
Published: March 2021

This paper is concerned with the impact of urbanization in aquifer well-system located in the Municipalarea of Arusha city, Tanzania. A system dynamic (SD) model was built under VENSIM PLE workbench fromtwenty-five years (1978-2003) physical and non-physical data to simulate their interactions and relations.This involved use of mathematics ideas and concepts in studying the physical and non – physical componentsseparately, and finally putting them together in new form (model) and study their relations. After model wasfound to be structurally complete and simulate properly by using the model and unit check tool of VENSIMPLE,parametric calibration of the model follows. Model output results were then compared with existing fieldconditions and information’s with the help of Excel spreadsheet. Historical data of population, rainfall, GDP,aquifer characteristics and land use was used as inputs. The model was trained for data series of 1978 to 1990and examined for data series of 1990 to 2003. Model efficiency criteria R2, suggested by Nash and Sutcliffe(1970), produced good results ranging from 0.6333 to 0.9868 during calibration and 0.9833 to 0.9985 duringverification. The model reveals that urbanization has enormous impact on population which was increasing ata rate of 4% from 1978 to 2003, which in turn caused increase in water demand for about 6% annually; as aresult aquifer well-system was overstressed due to over-pumping. Lastly a prediction of the situation for 2025was carried out in succession, and then interpretations and discussion concludes the paper.
Calibration of HDM4 for Use in Pavement Management Systems (PMS)
Authors: Mushule N.K.
Published: March 2021

One of major problems of road management in developing countries is the lack of decision making toolsfor preparing road maintenance programmes. This results in poor resource allocation and poor utilisationof existing assets. Pavement management systems (PMS) have been developed around the world in order to assist with the pavement management process in a co-ordinated and systematic manner. Some developed countries have derived pavement performance models that are suited to local conditions by setting up long term pavement performance studies. Conversely, most developing countries do not have the resources required to set up similar large-scale field experiments. However, validation and calibration of models developed from comprehensive studies elsewhere offers a viable lternative for such countries. This paper evaluates the feasibility of using HDM-4 as a support software and determines level 1 calibration factors for PMS in Tanzania. The paper demonstrates the use of a calibrated HDM-4 to determine the required road management information in developing countries.
Comparison of the Properties of Portland Cement and Portland-Limestone Cement
Authors: Mrema Alex Lyatonga
Published: March 2021

A study was made in a cement factory in Dar es Salaam, Tanzania, where OrdinaryPortland Cement (CEM I 42.5N) and Portland-limestone cement (PLC) which has thebrand name Twiga Cement Extra (CEM II/A-L/32.5R) are produced and conforming to theTanzania Standard TZS 727 (Part1): 2002, which is equivalent to EN 197 published by thecommittee for European normalization (CEN). A comparison was made between the twotypes of cements in terms of physical, chemical and mechanical properties. It was foundout that they all complied with the standards, that there was no significant difference intheir setting times and that the Portland cement had higher strengths than the PLC. It was also observed that there was a slightly lower water demand for the same consistency when compared to OPC and hence there is an improvement of the cohesiveness of a concrete mix when PLC is used. It was concluded, however, that the two cements are different and that using the two cements interchangeably as is done in Tanzania is wrong because they donot have equivalent strengths and therefore equivalent performance since the PLC is not ptimized. Portland-limestone cement (PLC) is known to offer significant energy savings and green house gas (GHG) reduction (up to 10% GHG savings) over conventional Portland cement while at the same time providing comparable performance if optimized.
Development of Pilot Plant for Bio-Ethanol Processing
Authors: Elisante Emrod
Published: March 2021

The paper outlines achievements obtained in developing a pilot bio-ethanol plant at the Department of Chemical and Mining Engineering (CME), University of Dar es Salaam. The pilot plant consists of: 30 L inoculums tank; 1,700 L fermenter; 1,500 L/day distillation column; and ancillary equipment. The prototype is a platform intended to be used for technology demonstration and research by graduate and undergraduate students studying the production of bio-ethanol using traditional and non-traditional raw materials like coffee mash, cashew fruit, and sisal inulin. The equipment has been developed using locally available engineering resources and the distillation column with 18 sieve tray measures 0.5m diameter 7 m high operates at atmospheric pressure. The condenser is cooled by 15 o C chilled water from utility lines and the reboiler is powered by 63 kW boiler installed at CME. Although the system includes biological, chemical and mechanical engineering details, only the important design issues are presented. A MATLAB code was developed forestimating the number of theoretical plates using the Mc Cabe-Thiele method. The water- ethanol vapour liquid equilibrium VLE data was obtained using relative volatilities estimated by Antoine equations for vapour pressure. The process design was done using various simulation packages and custom programs like Microsoft Excel for mass balance,Microsoft Visio for process and instrumentation (P&I) diagram AutoCAD software for mechanical engineering drawings. After performing hydraulic leak tests, the prototype was tested using blackstrap molasses 80 o brix which was prepared for fermentation using ilution and inoculums formulations developed in Microsoft Excel for water dilution, yeastand nutrients like (NH 4 ) 2 SO 4, KH 2 PO 4, MgCl 2. A batch mash boiling test conducted on the column showed that the response of tray temperatures exhibited first-order delay behavior with an average lag of 17 minutes and a delay of 50 -65 minutes depending on tray distance from the reboiler. Due to lack of feedback control equipment specifically on-linecomposition analyzers and suitable actuators, continuous control of ethanol composition could not be undertaken. It is planned to procure pertinent control hardware during the next phase of the project. However the batch test gave initial ethanol purity of 80% which decreased as the ethanol content in the still was continuously depleted.
The Effect of Service Installations on Structural Integrity of Slabs in Buildings
Authors: Lwambuka Ladslaus
Published: March 2021

In building construction industry service installations, usually housed in conduit pipes, are commonly mounted inside reinforced concrete structural elements. This practice is adopted to attain aesthetical outlook at both interior and exterior surfaces of the buildings. Depending on the extent of service installations, the cross sectional area of the load bearing structural member is substantially reduced. However, the current structural design guidelines have no provision to accommodate the extent to which the existence of conduit pipes impairs the load bearing capacity of the structural element though reduced cross sectional area. This study has attempted to address this gap in structural design ofbuildings; it involves assessing the current design practice of considering a structural element as a full solid body and comparing its ultimate load bearing capacity with the ones containing the conduit pipes. The study findings are based on test results from laboratory experiments on reinforced concrete slab models with varying intensity of conduit pipeinstallations as commonly practiced on construction sites. Recommendations are put forth when and how to consider the reduced load bearing capacity through the existence of service installations as part of structural engineering designs.
Flotation Circuit Performance Determination Using Size By Size Recovery – Case of Bulyanhulu Gold Mine
Authors: Maronga Silvanus J. , Ngoroma Faustine
Published: March 2021

The Bulyanhulu rougher flotation circuit performance has been determined by establishing the performance of individual cells. Direct sampling was done on all the rougher cellinput, output and size analysis was performed on the samples with material in each sizefraction assayed for copper and gold to determine their recoveries. It was observed that theperformance of rougher cell number 3 and 4 was poor compared to other cells especiallyfor finer particles below...
Illicit Trafficking Of Radioactive Sources: Experiences with Fake Materials in Tanzania
Authors: Pantaleo Peter , Kifanga Leonard D. , Mkihala Iddi S.N.
Published: March 2021

Radioactive materials although are very useful, they are one of the catastrophic sources ofmass destruction if misused. These materials have a number of positive uses which makesthem very essential in our modern society. Incidences such as the bombings of the USEmbassies in East Africa, the September 11, and many others had formed a basis forinternational responsive actions to control illicit trafficking of Radioactive and NuclearMaterials. The aim of this work is to track the movements and subsequently uses of thesematerials. Tanzania is one of the countries where International Nuclear Safeguardsprotocols are fully operational and observed. In the efforts of control, a number ofinstitutions have been mobilized nationally to the. While these control efforts are enforced,it is observed that several routes and different radioactive purported sources are importedto Tanzania. Although most of the motives of illegal trafficking intercepted have indicationof radioactivity through marking and signs, there are cases where the material has beenfalsified. On the other hand, the motive behind appears to be not only for use but ratherillegal dealings such as trading. This paper sites these incidences, their causes andinfluences on the control and proposes way forward.