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Articles 91 - 120 of 131
Full-Text Articles in Applied Mathematics
Study On Vortex Formation In The Pouring Basin By Direct Observation, J Runyoro
Study On Vortex Formation In The Pouring Basin By Direct Observation, J Runyoro
Tanzania Journal of Engineering and Technology (TJET)
Although the formation of vortex on the free surface of liquid draining from a container is often observed, relatively little is known about the phenomenon. When a liquid is drained from a container such as a bathtub through a bottom orifice, a dip on the surface known as vortex is formed. The vortex first appears as a small dimple in the free surface, which suddenly forms a cone-shaped hole. The vortex causes turbulences, which draws in air down into the orifice (drain). Generally, the issue of vortex formation is so common in our lives that possibly its occurrence seems to …
Comparison Of Two Different Transport Models To Predict Sediment Transport: Simiyu River, Tanzania, Case Study, F Mwanuzi1
Tanzania Journal of Engineering and Technology (TJET)
This paper presents the results of a study which focused at the spatial and temporal characteristics of sediment transport and deposition in the main river channels and floodplains. Two different numerical models were used to simulate stream flow and to analyze sediment transport and deposition in the river channels: (1) the SMS modules RMA2 and SED2D and (2) the SCALDIS model developed at the Free University of Brussels. Both numerical models contain a two-dimensional hydrodynamic module and a sediment transport module, allowing simulation of stream flow and sediment transport processes in river channels. However, they differ in the following aspects: …
Overview Of Hydraulics And Simiyu River Sediment Input Into Magu Bay, Lake Victoria, Tanzania, Alfonse Dubi
Overview Of Hydraulics And Simiyu River Sediment Input Into Magu Bay, Lake Victoria, Tanzania, Alfonse Dubi
Tanzania Journal of Engineering and Technology (TJET)
Lake Victoria is experiencing multifaceted environmental and ecological problems. A study of the problems needs a multidisciplinary approach. to establish the cause-effect relationships. The study focuses on the hydraulics of Lake Victoria's Magu Bay and Simiyu riverine input of suspended sediments and their distribution in the Bay. Sampling in the river mouth and the Bay was conducted aboard an 8m outboard engine wooden boat. Turbidity, currents speed and direction were measured using an "AANDERAA" multi-sensor self-recording current meter model 9 (RCM9). Water depth was measured using an echo-sounder type FISHIN' BUDDY II. Geographical positions of the sampling locations were obtained …
Gasification Kinetics Of Ultrafine Coal Char Oxidation In Flame Reactions, G John
Gasification Kinetics Of Ultrafine Coal Char Oxidation In Flame Reactions, G John
Tanzania Journal of Engineering and Technology (TJET)
Pulverized coal combustion is exceedingly complex with a vast number of variables. In order to avoid the complications associated with the burning of coal char, a controlled study has been made of the oxidation of fine graphite in laminar methane-air flame as a contribution to the understanding of the more complex phenomena of the gasification kinetics of the char. The burning of methane is equivalent to the burning of volatiles and graphite oxidation is similar to that of coal char. Aspects of this have been simulated in experimental and computational studies of 4pm diameter graphite particle burning in methane -air …
Socio-Economic Impacts Of Computer Viruses In Tanzania, M Victor
Socio-Economic Impacts Of Computer Viruses In Tanzania, M Victor
Tanzania Journal of Engineering and Technology (TJET)
This paper reports on a research project conducted with an objective of identifying and assessing various approaches used by different computer users (Management, System Administrators and end users) in Tanzania to combat computer viruses (CVs), and to assess users' awareness level on CVs. Specifically, the study aimed at assessing the awareness level on CVs to the Tanzanian business community; analyze the socio -economic impact caused by CVs in Tanzania and; assess existing methods, capacity and limitations on controlling CVs in Tanzania. Data was collected using both questionnaires and interview from financial institutions such as NBC and BOT, and telecommunications sector …
The Decomposition Kinetics Of Solids Thermodynamic Evidence For The Enthalpy Driven Cooling Of Reaction Environment Part 2, Akwilapo D
Tanzania Journal of Engineering and Technology (TJET)
The analysis of non-isothermal kinetic data for the decomposition of calcium carbonate, CaC03 (s) ~ CaO (s) + C02 (g) in flowing nitrogen, shows that the decomposition of solids is accompanied by self-cooling/heating of the reaction environment depending on the sample mass and heating rate. The correctness of the kinetic model is established by the calculation of the enthalpy change of the reaction. This is the thermodynamic evidence of endothermic enthalpy driven cooling of the reaction environment. The enthalpy change LJH = 179.33 kJmol-1 estimated from this work for the dissociation of CaC03 is in agreement with LJH = 179.17 …
Investigation Of The Stability Of Engine – Governor System Operated At Low Speeds, Cuthbert Mhilu
Investigation Of The Stability Of Engine – Governor System Operated At Low Speeds, Cuthbert Mhilu
Tanzania Journal of Engineering and Technology (TJET)
During diesel engine operation, a tendency for the engine not to achieve a steady idling speed has often been observed. During idling speed the engine tends to either race or stall as a result of poor and incorrect metering of the fuel, which is required for the combustion process and if severe, the engine will stop firing completely. 111 this research an investigation was made to establish knowledge on diesel engine stability operated at low speeds. The influence of a governor of an engine in the control of the engine speeds has also been investigated. In order to obtain information …
Short-Term Scheduling Of A Hydro-Thermal System Using Linear Programming Technique, A Kyaruzi
Short-Term Scheduling Of A Hydro-Thermal System Using Linear Programming Technique, A Kyaruzi
Tanzania Journal of Engineering and Technology (TJET)
The paper discusses the short term scheduling of Hydrothermal for Tanzania Electricity Supply Company (TANESCO) Power System. The problem is to determine on hourly interval the Hydro and Thermal generation. The scheduling keeps balance between production and consumption in a reliable and economical way during the study period. Linear programming (LP) mathematical model using MATL4B has been developed. The constraints are hydrological balance, thermal power plants limitations and load requirements. The result from LP solution gave low operation cost. Generation was mainly from hydro and all reservoirs elevation was high at the end ofplanning period.
Comparative Study Of The Dynamics Of Circulating Fluidized Bed Riser And Downer Of Equal Diameters, Samwel V. Manyele
Comparative Study Of The Dynamics Of Circulating Fluidized Bed Riser And Downer Of Equal Diameters, Samwel V. Manyele
Tanzania Journal of Engineering and Technology (TJET)
The microscopic flow dynamics of the 100-mm internal diameter riser/downer circulating fluidized bed (CFB) unit were monitored using a solids concentration fiber optic probe. The comparison was conducted by comparing radial profiles Of the dynamic parameters derived from time-series analysis techniques (statistical and chaos analyses). The solids concentration signals used were recorded under similar operating conditions (gas velocity of 8.0 m/s and solids flux of 100 kg/m2s). Similar axial elevations were compared (entrance and fully developed sections of die reactors). A1 each loca!ion, the signals were sampled a! afrequency of 970 Hz for duration of 30 seconds. It was observed …
Assessment Of The Accuracy Of Approximate Methods In The Analysis Of Plane Frame Structures, I Rubaratuka
Assessment Of The Accuracy Of Approximate Methods In The Analysis Of Plane Frame Structures, I Rubaratuka
Tanzania Journal of Engineering and Technology (TJET)
pproximaic methods of analysis are widely used in the analysis OJ' frames for preliminary design due to their simplicily as compared to exact analysis meth o ds Ough they a re nol as accurate. In this paper. the methods Of hinges and portal frame are described and have been used to analyze a statically indeterminate frame by taking inro account the bending stiffness of the frame members. The obtained results are comparable Io the magnitudes of forces determined by exact methods Of analysis.
Derivation And Analysis Of Maximum And Conditional Work Of An Electromagnet In Relays With Small Gaps And Constant Armature Load, Dominic Chambega
Derivation And Analysis Of Maximum And Conditional Work Of An Electromagnet In Relays With Small Gaps And Constant Armature Load, Dominic Chambega
Tanzania Journal of Engineering and Technology (TJET)
No abstract provided.
Mathematical Simulation Of The Influence Of Volatile Ma•Rrer Cloud On Heterogeneous Ignition Of Single Coal Particles, Hassan Ratal Ambula
Mathematical Simulation Of The Influence Of Volatile Ma•Rrer Cloud On Heterogeneous Ignition Of Single Coal Particles, Hassan Ratal Ambula
Tanzania Journal of Engineering and Technology (TJET)
Asimple model has been developed to predict the heterogeneous ignition temperature for single coal particles under conditions of negligible, natural and forced convections. These conditions cause different sizes Of volatile matter cloud that surround the coal particle. The model is based on the ignition Of a single coal particle heated by irradiation from spot heaters in a cold (ambient) surrounding. Energy from the particle surface oxidation, volatile matter combustion and physical heating from the spot heaters are all included in rhe particle energv balance. General ignüion criterion is used to determine the ignition point. The agreement between the experimental and …
Review Of The Product Development Process And Information Flow In The Manufacturing Industry: Problems And A Possible Wav Forward, E Opiyo
Tanzania Journal of Engineering and Technology (TJET)
No abstract provided.
Probabilistic Load Flow For Mv Radial Distribution Networks Supplying Statistical Loads, B Kundy
Probabilistic Load Flow For Mv Radial Distribution Networks Supplying Statistical Loads, B Kundy
Tanzania Journal of Engineering and Technology (TJET)
Aecurate load models are required Jör 'he computation OJ' load on Medium Voltage (MV) distribution net•.vovk.s_ Modern microprocessors in recent times have enabled researchers stunple and log domestic loads. The findings show that domestic loads are stochastic in nonwe and are best described bv u beta probability distribution [Herman et al. 1999]. The statistical evaluafion lhe consumer voltages requires description load currents al rhe lime e/ lhe system maximum demand. In this paper. an analytical 1001 computing voltage vegulation on MV distribution net-norks fi•eding statistical louds is presenled. To deal beta- distributed currents on MV distribution networks, new scaling factors …
Electrokinetic Cha Raci'erisation Of Colloidal A-Alumina, J Ntalikwa
Electrokinetic Cha Raci'erisation Of Colloidal A-Alumina, J Ntalikwa
Tanzania Journal of Engineering and Technology (TJET)
Electrophoretic mobility (uD is an important rneasurable parameter in studying the electrokinetic properties of a colloid dispersion. This parameter is Often convened into zeta potential (C) Which piays a great role in thc description Of the stability towards aggregation Of dispersed particles. In this paper, measurements of Of colloidal a-alumina dispersed in various concentrations of electrolyte arc reported. It was observed that, the isoelectric points (the pH at which us = O) occurred at 7.52 ± 0.32, 8.05 ± 0.11 and 7,95 ± 0.18 in Naci, KCI and NaNOs respectively. The isoelectric point was observed to be a function Of …
Comparative Analysis Of Rng K-E And 'Standard' K-C Models For Fluid Flow Around A Cylinder, A Temu
Comparative Analysis Of Rng K-E And 'Standard' K-C Models For Fluid Flow Around A Cylinder, A Temu
Tanzania Journal of Engineering and Technology (TJET)
A two-dimensional computational scheme for simulating fluid flow around a cylinder was investigated. RNG (Re-NOrmalisation Group) and 'standard' turbulent closure models were used. simulation was implemented with assistance OfFLOW-3D computational fluid dynamics (CFD) code. The governing equation Of fluid motion, in Eulerian form, included body forces as well as surface forces. The computational model predictions for fluid velocity showed good agreement between the two models. Comparison Of the viscosities showed a large deviation from the two models, with RNG k-E model giving a better approximation. Comparison Of the velocity around the cylinder, as obtained from RNG k-c model, with approximation …
Baseflow Separation Based On Storage-Outflow Modelling Of Streamflow Recessions, With Application To Semi- Arid Catchments In Tanzania, S Mwakalila
Tanzania Journal of Engineering and Technology (TJET)
Discharge in many rivers is Often fed by baseflow provided by drainage of the saturated zone in the shallow permeable soils. It is becoming clear that the outflow from this saturated zone is not linear proportional to storage as is commonly assumed in many algorithms. The objectives Of this study theretore, are first to explore the extent to which the assumption of linearity in storage-outflow relationships is valid and secondly to introduce an alternative approach to baseflow separation algorithms for estimating direct mnoff time series. Numerical analysis Of streamflow recessions from the semi-arid catchments of the Great Ruaha basin in …
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.
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 …
Turbulent Burning Model For Premixed Gaseous Mixtures, E Mushi
Turbulent Burning Model For Premixed Gaseous Mixtures, E Mushi
Tanzania Journal of Engineering and Technology (TJET)
A turbulent burning model for premixed gaseous mixtures has been successfully developed. The model assumes instant burning of vortex Tubes of the order of Kolmogorov scale followed by burning of larger eddies of the order of Taylor micro scale. These eddies burn ar a rate dependent On the stretch rate. The influence of turbulence on the burning rate is introduced in the form of probability density function which gives the probability that a given mixture under turbulence will undergo burning rather than being quenched. The model has been validated againsi experiments involving turbulent explosions in a fan stirred bomb. Model …
A Comparison Of Three Numerical Methods Of Solutions Of Equations Describing Unsteady Gas Flow At Pipe Boundaries In Reciprocating Compressor Systems, M Mkumbwa
Tanzania Journal of Engineering and Technology (TJET)
A number of finite difference schemes are available to study pressure fluctuation effects in unsteady pipe flows. This paper presents a comparison Of the predictions made by three such schemes of unsteadyjlow effects in a number of reciprocating compressor pipe-work systems. The finite difference schemes considered were;- a first order scheme known as the method Of characteristics, two second order schemes which were the Leapfrog method and MacCormacVs method. A reciprocating compressor simulation computer program was coupled with equations describing the cylinder thermodynamic processes with the pipe flow equations for steady non-homentropicflow. The comparison presented takes into account both the …
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 …
Extracting Consistent Weight Ratio Matrices From Inconsistent Judgement Matrices., Christian Alphonce
Extracting Consistent Weight Ratio Matrices From Inconsistent Judgement Matrices., Christian Alphonce
Tanzania Journal of Engineering and Technology (TJET)
The Analy,'ic Hierarchy Process (AHP) developed by Saaty Inore (han a decade ago has been widely applied in diverse decision making problenls ranging from socio-economic planning to engineering designs. One of the basic steps of this popular decision support tool is concerned with estimating a ratio scale of a set of entities from their inconsistent pairwise comparison judgement matrix. A number of estimation procedures for this purpose have been proposed. These include Saaty's eigenvector meihod, various geometric means methods, and methods using logarithmic least squares, least squares. and means Transformanons, amongst O,'hers. One Thing conunon to all these Inethods is …
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.
Model For Complete Drawdown Of Floating Solids In Stirred Tank Reactors, J Mmbaga
Model For Complete Drawdown Of Floating Solids In Stirred Tank Reactors, J Mmbaga
Tanzania Journal of Engineering and Technology (TJET)
A Semi-empirical model has been developed on the basis of Kolmogoroff's theory of isotropic turbulence to determine the minimum drawdown speed for floating solids in a mechanically agitated vessel. An adjustable pa- rameter in the model is found to be afunction of impeller type and position in a vessel. A simplified representation of macroscopicflow pattern, rep- resenting the circulation flow in a vessel depending on impeller pumping characteristic is developed to account for recirculation pattern.
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 …
Influence Of Turbulence On Methane-Air Flame Speed, E Mushi
Influence Of Turbulence On Methane-Air Flame Speed, E Mushi
Tanzania Journal of Engineering and Technology (TJET)
Experimental study Of the influence qfturbulence on flame speed for meth- ane-air mixtures has been conducted in afan stirred bomb using schlieren photography. It has been observed that turbulence increases flame speed but above KLe=O. 18 (KLe is the product Of the dimensionless Karlovitz flame stretch factor and the Lewis number) turbulence quenches the flame. Inminarflame kernel is observed to prevail in the early stages of flame development in a turbulent mixture. Further, the laminar burning velocity plays a significant role in turbulent combustion. It is proposed that the increase in flame speed is a result of flame wrinkling.
A Check Parameter Method For Use In Designing Relays, H Kadete
A Check Parameter Method For Use In Designing Relays, H Kadete
Tanzania Journal of Engineering and Technology (TJET)
Low quality magnetic steel available locally has been successfully used as core material for a relay. New design principles as well as construction procedure used in development of a prototype are presented. Then the new approach is assessed and found to deliver acceptable accuracy.
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 …