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Articles 151 - 180 of 201
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The Behaviour Of Reinforced Block-Work Walls In Axial Tension, Laurent Shirima
The Behaviour Of Reinforced Block-Work Walls In Axial Tension, Laurent Shirima
Tanzania Journal of Engineering and Technology (TJET)
Reinforced blockwork with horizontally laid reinforcing bars is used for walls in liquid retaining structures in developing countries. This is the case where, the level of technology in terms of skills and equipment is not in a position to allow successful construction of reinforced concrete walls. Blockwork walls are very sensitive to cracking which cannot be prevented by reinforcement. The major problem for designers is the behaviour of such walls in tension caused by hydrostatic pressure of the stored liquid. This paper reports results of a research work to study the behaviour of reinforced blockwork walls in tension. It was …
Application Of Vibrational Techniques In Determination Of Dynamic Properties Of Agricultural Products-State Of The Arton Of Vibrational Techniques In Determination Of Dynamic Properties Of Agricultural Products-State Of The Art, Silas Kajuna
Tanzania Journal of Engineering and Technology (TJET)
Vibration is one of the techniques employed in the determination of dynamic properties of fruits and vegetables. It entails generation of a mechanical or acoustic vibrational signal which is propagated through the flesh of the agricultural material. A transducer is either attached or held close to the specimen to monitor the propagation of the signal through the specimen. The manner in which the signal is transmitted through the material is analyzed, and the dynamic properties of the specimen which relate to its firmness or its internal being are derived. The technique has been around for the past 30 years or …
Evaluation Of Extreme Wind Speeds In Relation To The Design Of Coastal Structures In Tanzania, Alfonse Dubi
Evaluation Of Extreme Wind Speeds In Relation To The Design Of Coastal Structures In Tanzania, Alfonse Dubi
Tanzania Journal of Engineering and Technology (TJET)
Five distribution functions, FT-I and Weibull with the exponent k = 0.75, 1.0, 1.4 and 2.0 respectively, have been applied to 25-year wind data collected between 1972 and 1996 at Tanga, Dar Es Salaam, Zanzibar and Mtwara Meteorological stations. One maximum value for every year from the full data record was drawn to constitute the annual maxima series for each station. For each of the stations, 2-, 50- and 100-year return wind speeds with corresponding 90% confidence intervals were computed. The distribution functions were fitted to the data by the Least Squares Method. Results from the study show that FT-I …
Mathematical Modelling Of Road Bumps, E. S. Massawe
Mathematical Modelling Of Road Bumps, E. S. Massawe
Tanzania Journal of Engineering and Technology (TJET)
In this paper, a general mathematical model that may be used for construction of a road bump on an inclined road is developed. It is shown that if the parameters for the inclination are set to zero, the resulting model reflects the special case of a flat road. Existing experiences are briefly highlighted and a case study was done on different locations along the University Road to demonstrate the developed model.
Evaluation Of Soil Conservation Measures: A Case Study In Mbinga District, Ruvuma Region, Tanzania, S. Y. Thadei
Evaluation Of Soil Conservation Measures: A Case Study In Mbinga District, Ruvuma Region, Tanzania, S. Y. Thadei
Tanzania Journal of Engineering and Technology (TJET)
A study on soil conservation measures was conducted in two villages, Tukuzi and Mahenge, in Mbinga District, Ruvuma Region, Tanzania. The results showed that the ngoro farming system was effective in controlling soil erosion by water on both steep and gentle slopes. Sediments collected from ngoro had high concentrations of plant nutrients such as available phosphorus (P), total nitrogen (N), organic carbon (OC) and exchangeable bases. This was probably due to nutrients released from decomposed grass bundles buried in the soil. In preventing soil erosion, ngoro and bench terraces were equally effective, while contour ditches were as effective as ridges …
Concrete Cracking In Coastal Areas, S. R. Mpinzire
Concrete Cracking In Coastal Areas, S. R. Mpinzire
Tanzania Journal of Engineering and Technology (TJET)
The paper discusses cracking and corrosion of reinforced concrete (RC) structures in coastal zones where aggressive action of salt burdened air is the primary cause of concrete deterioration. Case studies are presented, along with discussion of possible remedies including local demolition, reconstruction and epoxy injection as well as concrete treatment.
The Development Of Groundwater For Water Supply, C. F. Mhilu
The Development Of Groundwater For Water Supply, C. F. Mhilu
Tanzania Journal of Engineering and Technology (TJET)
ABSTRACT This paper presents results of groundwater investigations carried out at Yombo Dovya Village, Temeke District in Dar es Salaam Region. The study has included hydrogeological and geoelectric resistivity sounding survey data obtained at the test site in Yombo village. The results of this investigation based on the application of vertical electrical sounding probe predictions have indicated the existence of reasonable amounts of groundwater resource for development. To verify these results borehole drilling tests were also conducted at the same site (Borehole No. DSM 79/99), and the results obtained by this method compares very well with those obtained earlier by …
Estimating The Usle - Soil Erodibility Factor In Developing Tropical Countries:A Case Study In Tanzania, Metthew Mulengeral
Estimating The Usle - Soil Erodibility Factor In Developing Tropical Countries:A Case Study In Tanzania, Metthew Mulengeral
Tanzania Journal of Engineering and Technology (TJET)
Developing countries in the tropics are facing more soil erosion problems than the developed temperate countries. These developing countries have no accurate locally applicable equation(s) for predicting soil erosion or for planning and implementation of soil conservation measures. Furthermore, These countries do not have the necessary resources to develop the soil loss prediction equation(s). Existing empirical equations like the Universal Soil Loss Equation (USLE) if modified to suit tropical conditions can be useful a tool in soil erosion control in the region for a foreseeable future. In this paper equations'for estimating the soil erodibility factor in the USLE for tropical …
Technical And Economic Comparison Of Performance Between Farmer And Government Managed Irrigation Schemes In Tanzania: A Case Study Of Kapunga Irrigation Project, D Chemka
Tanzania Journal of Engineering and Technology (TJET)
This paper conwares the perforinance Of governnyent ro fanner-managed irrigation schemes at Kapunga Rice Project in Mbeya Region, south-west Tanzania. The results showed that the farmer-managed irrigation scheme (FMIS) performed better than the government-managed irrigation scheme (GMIS) in attaining good performance. Applicable indicators for farmer-managed irrigation scheme are as shown below with those of government-managed scheme indicated in brackets. Its overall irrigation efficiency was 61' percent (29 percent) average productivity was 3.2 ton/liG (2.2 ton/ha); economic profirability: internal rate of return was 3.2 percent (5 percent), benefit/cost ratio of 0.60 (0.14); while its financial profitability: internal rate of return was …
Sustaina Bility Of Irrigation Schemes For Small-Scale Farmers: A Case Study Of Irrigation Scheme At Buleya Malima, Gwembe Valley, Zambia, Masinja R
Tanzania Journal of Engineering and Technology (TJET)
A study to determine facrors influencing sustainability of smallholder irrigation schemes was carried our a! Buleya Malima, Southern Province, 7_nnzbia. These factors included technical and socio-economic factors. found Out that the technical factors were 26.5, 64.5 and 9.2 percent for application efficiency, tailwater ratio and deep percolation, respectively, indicating that farmers wasted water mainly through tailwater runoff.From socio-economic point of view, the study indicated that the scheme lacked (i) farmer participation in designing and planning operation of the scheme (ii) managerial ability and innovativeness to form their own viable organisation: and (iii) formal training in technical operations of irrigation, infrastructure …
Experimental Study Of Rural Brick Burning In Iringa And Mbeya Regions, E Mushi
Experimental Study Of Rural Brick Burning In Iringa And Mbeya Regions, E Mushi
Tanzania Journal of Engineering and Technology (TJET)
In this paper results are presented Of a study conducted between June and December 1997. on nine brick firing kilns in Iringa and Mbeya. The locations for rhe study were Mahenje and Iloniba in Mbeya Region and Igumbilo in Iringa region. Three kilns were investigated in each location. For each kiln the process was followed from the laying Of the bricks into a kiln to the opening Of thc kiln for renu)val Of the bricks in preparation for the selling. Different weights and tenperatures were Taken a,' different times. Firing wet bricks results in consumption of 33.63 % of the …
Development And Evaluation Of A New Soil Erosion- Productivity Index Model (Sepim), Metthew Mulengera
Development And Evaluation Of A New Soil Erosion- Productivity Index Model (Sepim), Metthew Mulengera
Tanzania Journal of Engineering and Technology (TJET)
A soil erosion-productivity model which considers rhe effect of soil water storage Capacity. crop evapotranspiration, soil chemical and physical properties inrporrantfor Crop growth has been developed. The model is shown to give good predictions and it promises to be an improvement over the former productivity Index (PI). It also promises to give more reliable results than the currently used /nodels which consider only soil water storage capacity and crop e ' 'apotransp iration.
Use Of Dissolved Oxygen Concentration Probes In Biological Wastewater Treatment Plants, S Manyele
Use Of Dissolved Oxygen Concentration Probes In Biological Wastewater Treatment Plants, S Manyele
Tanzania Journal of Engineering and Technology (TJET)
A study on use Of dissolved oxygen probes (DOP) for measurement Of oxygen concentration in warer and wastewater treatment is presented. The principles Of operation, design considerations and selection criteria for Two types of probes, viz. galvanic and polarographic, are discussed Use of polarographic probes in n rhree-phase fluidized bed bioreactor and in laboratory experiments is presented and discussed. The effect of airflow rate and treatment time on dissolved oxygen concentration was found to be significant. It was found that polarographic probes are important equipment in determining the pollution of the industrial effluents. Finally, the use of the DOC probes …
Power Shedding Experiences And Lessons In A Township, Alexander Kyaruzi
Power Shedding Experiences And Lessons In A Township, Alexander Kyaruzi
Tanzania Journal of Engineering and Technology (TJET)
This paper presents how power shedding by taking out one of the trans- former high voltage fuses causes phase imbalance. And for the same elec- nicc,l energy output generator fuel consuntption with unbalanced phases is 12.5% of The fuel consunwtion with balanced phases. Furthermore it is shown thal energy efficient lighting by use of energy efficient bulbs can reduce load shedding.
Optimum Geometrical Parameters For Prismatic Folded Plate Roofs: System- Atic Search Approach, N Mwitta
Optimum Geometrical Parameters For Prismatic Folded Plate Roofs: System- Atic Search Approach, N Mwitta
Tanzania Journal of Engineering and Technology (TJET)
Folded plate structures have unique structural advantages over conven- nonal beam-and-slab structural forms. Selection of optimum geometrical parameters in design would make folded plate roofs more appealing to the national construction industry in terms ofcost. This paper presents a study on shape optimization of prismatic folded plate roofs for minimum weight of the structure per unit covered area. A computer based systematic search approach has been employed.for the optimization study, while the tranyeer matrix method has been used for analysis. Curves opriinum geometrical parameters versus span have been pre sented for three commonly used shapes of prismatic folded plate roofs. …
Regionalization Of Hydrologic Information In Tanzania (Low Flows), Onyekwuluje C
Regionalization Of Hydrologic Information In Tanzania (Low Flows), Onyekwuluje C
Tanzania Journal of Engineering and Technology (TJET)
Hydrologic infornjation is required for the planning and design Ofwater resource projects. However, Hydrologic infonnation is always lacking at points of interest. Regionalization is ained at estimating hydrologic infor- mation such as low flow statistics at ungauged sites. Hydrologic informa- tion from 63 catchments in Tanzania has been analysed. In this paper, pooled flow duration curves for 1, IO, 30, 60, and 90 days duration have been established. Regression equations between the low flow indices (i.e. 95 percentile and for a IO day duration, average annual yield (AAY), av- erage daily flow (ADE)) and catchment characteristics were developed. The pooled …
Optimal Capacity Allocation Truck Industry In Tanzania:A Case Of National Transport Corporations(Ntc), R Mgaya
Tanzania Journal of Engineering and Technology (TJET)
This paper tries to examine truck transportation service in Tanzania, particularly, in National Transport Corporation’s subsidiary companies - Regional Transport Companies. It provides an analysis based on operations research approach on resource allocation, specifically, truck allocation, with an aim of trying to minimize running costs and hence improve profits. It is established that there had been higher running costs and hence decline of profits in some Regional Transport Companies due to misallocation of capacity. However, this problem had been compounded by some other factors as discussed in the paper. It is recommended that these Regional Transport Companies and other transport …
A Conceptual Approach To Water Resources Management For A Catchment In Tanzania, F Mwanuzi
A Conceptual Approach To Water Resources Management For A Catchment In Tanzania, F Mwanuzi
Tanzania Journal of Engineering and Technology (TJET)
In hydrology/Water resources, normally rainfall data are available for longer periods than runoff data. Many attempts have been made to extend these runoff data by using system approach and conceptual models. The conceptual approach to simulate runoff at the outlet ofa catchment is based on the physical processes involved in the transformation of rainfall into runoff (river flow). In this paper a conceptual model, (SEAMOD) has been used. This model has a limited number of parameters to optimize when compared to other models like the sacramental model. Also it requires less input data. The model assumes that the storage is …
Critical Evaluation Of The Effects Of Changes Made To Roughing Filters Of Mpira-Balaka Plant On Its Treatment And Operational Performance, C Zulu
Tanzania Journal of Engineering and Technology (TJET)
Mpira Balaka, a full scale rural water supply project was constructed in Ntcheu, Malawi, in 1988 utilising Slow Sand Filtration (SSF) as the main treatment process and roughing filtration as the pretreatment method,following the promo- tion of this technology by various international institutions. During the rainy seasons, the treatment plant for Mpira Balaka failed to cope with the high raw water turbidity, resulting into very short filter run times and hence also to unavoidable distribution Of very turbid water to the rural communi- ties as a result Of by-passing the filters. Of the fifty or so existing rural projects in …
Effect Of Reduced Plate Width On The Structural Behaviour Of A Triangularly Folded Plate Barrel Vault, S Manyele
Tanzania Journal of Engineering and Technology (TJET)
Various methods of analysis have been employed to predict the structural behaviour of the Triangularly Folded Plate Barrel Vault, with conflicting results. A review of past analytical and experimental investigations carried out on the structure show that theoretical analysis based on a smaller effective width rather than the overall plate width is capable of closely predicting the deflection behaviour of the structure. This paper presents an experimental study of the behaviour of a triangularly folded plate barrel vault with physically reduced plate width. It is found that physical reduction of the plate width to correspond to ‘theoretical’ effective width weakens …
The Performance Of A Horizontal Flow Roughing Filter/Slow Sand Filter Water Treatment Plant In Tanzania, Mbwette T. A
The Performance Of A Horizontal Flow Roughing Filter/Slow Sand Filter Water Treatment Plant In Tanzania, Mbwette T. A
Tanzania Journal of Engineering and Technology (TJET)
The performance of a water treatment plant comprising of the Horizontal f Iow Roughing F i Iter (HRF) / Slow Sand Filter (SSF) System was evaluated by monitoring the water quality of the inlet water and the plant filtrates for a Improper operational procedures and period of two months. the absence of adequate maintenance of the plant was found to have resulted to relatively Iow removal efficiency. This subsequently improved as a result of plant rehabilitation and introduction of new operational procedures and became comparable to the performance of HRE/SSF plants documented in literature. For example, as a result of …
Optimization Of Dispersed Flor Pond For Bacterial Removal, Mayo A. W
Optimization Of Dispersed Flor Pond For Bacterial Removal, Mayo A. W
Tanzania Journal of Engineering and Technology (TJET)
The design of waste stabilization ponds is seldom done with consideration of optimum pond dimensions. The analysis of pond dimensions within practical limits in dispersed flow ponds on the basis of minimum cost for the predetermined bacterial remova) ef ficiency, with the aid of computer is presented. The data collected in the pilot and full scale waste stabilization ponds at the University of Dar es Salaam Was used as input to the computer program. The results shows that pond configuration and climatic conditions which have influence on bacterial mortality rate have a re:narkable influence on pond cost
Hydrodynamic Stability Of The Breakwater Extension At Rrviksand, Norway, Alfonse Dubi
Hydrodynamic Stability Of The Breakwater Extension At Rrviksand, Norway, Alfonse Dubi
Tanzania Journal of Engineering and Technology (TJET)
The fishing port of Årviksand in Norway, which is situated on an open coast, is artificially harboured by breakwaters. The northern and southern breakwaters which were built in 1930—ies and 1950—ies respecti vely have been on several occasions damaged by heavy storms. This resul ted in the need for further protection by extending the northern breakwater. This paper describes one of the hydrodynamic tests on the breakwater extension. The breakwater, with a berm breakwater concept design, is subjected to the joint probability of sea level elevation and wave heights (in other 'fatigue" test). words , It is found that cover …
Evaluation Of Wind Data Records To Predict Extreme Extreme Wind Speeds In Tanzania, L Lwambuka
Evaluation Of Wind Data Records To Predict Extreme Extreme Wind Speeds In Tanzania, L Lwambuka
Tanzania Journal of Engineering and Technology (TJET)
The progress made towards evaluation of local wind data records to pred ict extreme values of wind speeds in Tanzania is being presented . Records of wind data, stored continuously since 18 years, have been compiled and statistically processed. Extreme value theory of Fisher —Tippet Type I has been fitted into the data to abstract extreme values of wind speeds for locations at which the wind data records were obtained. A reliable wind map of Tanzania containing basic wind speeds at 18 locations across the country has been produced. The basic wind speeds are being recommended for des ign against …
The Hydraulic Performance Of A Vortex Tube Foector, F Mtaro
The Hydraulic Performance Of A Vortex Tube Foector, F Mtaro
Tanzania Journal of Engineering and Technology (TJET)
The vorle.r tube silt exrrac/or consists of a pipe, rhe crest of which has a slit and lies flush across lhe canal bed.With minimal warer loss, I.oe bedload is extracted through lhe slil settling canal back ro the river, thus reducing or eliminating the bedload transported in main canal. Ihe resulting swirling flow phenomena is of complex nature and depends on sc conirol paramerers, as a result of which previous empirical design approaches have yielded conflicting guidelines. By means Of a simplified hydraulic system, the flow mechanism and energy in rhe can be determined.
Parking Demand And Supply In The Central Business District Of Dar Es Salaam City, Theophil Rwebangira
Parking Demand And Supply In The Central Business District Of Dar Es Salaam City, Theophil Rwebangira
Tanzania Journal of Engineering and Technology (TJET)
The Central Business District (CBD) Of Dar es Salaam city is currently experiencing severe congestion. Among the major causes of this condition is lack cf enough parking facilities. Obstructions due to vehicles parked on the roadway and increased vehicle circulation by drivers looking for a mace to park This paper reports on a recent study are major contributors to congestion. which evaluated the demand and supply as vell as usage of parking spaces in the CED. The f indings indicate that there is currently an acute shortage Of parking spaces, especially of off—street parking spaces. For the existing facilities, there …
Flood Forecasting In Tanzanian Catchments, Omari Rumambo
Flood Forecasting In Tanzanian Catchments, Omari Rumambo
Tanzania Journal of Engineering and Technology (TJET)
Floods are still a problem to many countries in the world todate. Floods do cause damages to property and sometimes loss to human life. Flood control measures by structural and non—structural methods are avail able in the literature . However , structural flood control measures are financially infeasible in most developing countries today. Flood forecasting is a non—structural measure for reducing flood damages. It is a means of providing early The Li near f 1 ood warnings to flood prone areas . Perturbation Model has been appl ied for real time flood The Linear forecasting in Tan zanian catchments . …
Experimental Investigations On The Behaviour Of Wood In Transverse Compression, A Mrema
Experimental Investigations On The Behaviour Of Wood In Transverse Compression, A Mrema
Tanzania Journal of Engineering and Technology (TJET)
Experimental investigations were done to study the behaviour of wood in transverse compress ion. Three key variables were incorporated in the experiments to study their influence on the •nriables were the orthotropic ratio of the behav iour. These material, the geometry of loading and that of the specimen . Deformation measurements were made at selected locations on test specimens by means of strain—gage based clip gages. Results from the experimental measurements were compared to previous deformation predictions made by a finite element analysis (9) . There is a very good agreement between measured values and those obtained trom the finite …
Design, Operation And Maintenance Considerations Of Iiorizontal Flow Roughing Filters Preceding Slow Sand Filters, T Mbwette,
Tanzania Journal of Engineering and Technology (TJET)
The paper mentions some of the reported uses of Horizontal Flow Roughing Filters (IIRF) in drinking water treatment plants in Europe before briefly reviewing research activities carried out in the use of IIRF prior to Slow Sand Filters. Design, operation and maintenance aspects Of HRF are reviewed on the basis of the laboratory and field tests carried out in Tanzania and Switzerland, respectively in addition to experience gained in operation of a number of plants already built to date. Design aspects are introduced from the point of view Of its philosophy and optimization strategies before design guidelines are given. Important …
The Stability And Sate Dimensioning Of Circular Masonry Arches, A Mrema
The Stability And Sate Dimensioning Of Circular Masonry Arches, A Mrema
Tanzania Journal of Engineering and Technology (TJET)
An analysis of masonry arches where collapse is assumed to occur by the hinging of voussoirs upon each other is made. The behaviour of the arch material is assumed to be such that the plastic theory is valid. Certain aspects related to the properties So far the approach by of the line of thrust are clarif led. writers has been based on the conventional view that the 1 ine of It is shown that pressure is tangential to the line of thrust. this is not the case in general. Definitions are given on what is meant by "line of thrust" …