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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 …

Optimum Design For Spring With Orthogonal Design Method, Han Fu - Jie

Tanzania Journal of Engineering and Technology (TJET)

Orthogonal design method is a sort of direct optimum method, by which the op- timal result may be obtained through simple computation and analysis. This method has gained increasingly extensive interest in scientific research, engineering design, end production management as well. The orthogonal table is the basic instrument for carrying out optimum design with orthogonal design method. It is a mathernatical table established On the basis Of the idea of isostatic distribution. As various levels may appear in any column, it makes a partial experiment contain levels of all factors furthermore. RII combina- tions of any two columns may appear …

Development And Testing Of Locally Produced Natural Rubber (Nr) And Pvc Blends, B Mutagahywa

Tanzania Journal of Engineering and Technology (TJET)

The mechanical properties of natural rubber - poly(vinyl chloride) blends have been studied. Tensile and tear strengths of the vulcanizates has been shown to increase with increasing proportions of PVC up to about 20 pphr. Abrasion loss and hardness decreases slightly with increasing concentration of PVC. Increased loading Of carbon black lowers the tensile and tear strength while increasing the abrasion loss and hardness values. This may be explained by the fact that PVC exists as a discontinuous rigid phase in the polymer compound. At normal loading of black (37 pphr) PVC improves processability and acts in the same way …

Antecedents, Moderators And Outcomes Of Organizational Commitment, Beatus Kundi

Tanzania Journal of Engineering and Technology (TJET)

This study examined: (I) the impact of the BtruCturaI of tenure, job integration and organizational support on organizational (2) the mediating roles of the cultural values for performance and collectivity, and the intra—individual factorg of organizational identification and the norm of reciprocity Ln the relationahip between the structural factore and organization coamitment; and, (3) the relationghip between organizational cormitment and the ouecome variablen Of abøeneeeigm, turnover and The Bhow that job and Of the for performance a gignificant facilitator of the effecte Of the etructuraL factors on commitment; and organization identification and the norm of rec are important linkø in …

Effect Of Various Control Regimeson Insect Pests And Seed Yield Of Beans, Chipungahelo G.S.E, A.K. Karel

Tanzania Journal of Science

The effect of various control regimes on insect pests and seed yield was studied in common (Phaseolis vulgaris L.) beans. Two varieties namely Selian Wonder and Canadian Wonder were used. Four treatments of insecticide were used namely, full control (control throughout the growing seasons), control before flowering, after flowering, and no insecticide application. Endosulfan 35EC was sprayed at the rate of 800 g A.l. per 500 l of water per application. In this study both pre-flowering and post flowering pests were important. They included Ootheca bennigseni, Maruca testulalis, Heliothis armigera and Anoplocnemis curvepes. In addition a number of less …

Theoretical Analysis Of Thermodynamic Consistency Of A Reiner-Rivlin Fluid, V.G. , Masanja

Tanzania Journal of Science

The thermodynamically admissibility of a Reiner-Rivlin fluid undergoing a two dimensional axisymmetric flow process has been investigated analytically. The Clausius-Duhem inequality shows dependence of the viscosity coefficients on kinematical quantities, hence no general restrictions can be made on the non-Newtonian viscosity coefficient. However specific restrictions have been made by considering a cubic degree fluid. It is concluded that the rheological equation of state is an approximate model of the constitutive behavior of a real fluid and that the thermodynamic consistency of a flow process can basically be proved numerically.

An Account Of Sandbank Depositional Modes, Menai Strait U. K, N. Nyandwi

Tanzania Journal of Science

Grain size distribution on the seabed and in the suspension were determined on an intertidal sandbank in Menai Strait, U.K. to establish both the mode of deposition and its stability against the strong tidal flows prevailing in the strait. Granulometric analysis showed typically three sediment population (log plot of cumulative curve) in the size range 4.0-3.0 phi and 1.5-1.0 phi with the middle on making the largest in all the samples. A probability plot of the cumulative curves however revealed on the average the lower (coarse) and upper (fine) truncation points to be lying at 1.5 phi and 3.0 phi …

Surface Carbon Formation On Pt/ˠ-A12o3 From C3 And C4 Hydrocarbons Part 1: Kinetics Of Carbon Formation, L.L. Mkayula

Tanzania Journal of Science

Carbon formation on an Esso reforming type catalyst Pt/γ-A1₂O₃ by C₃ and C₄ hydrocarbons has been studied at atmospheric pressure and within a temperature range of 450-600⁰C using a microbalance capable of detecting up to 10^-6 g by weight of coke. A kinetic model initially developed by Froment has been used to analyze the transient regime of coke versus time curves. Deactivation function-reaction mechanism relations have been proposed and applied to the coking results. Carbon deposition rates are highly dependent on temperature, partial pressures of reactant, nature and composition of reactions, and …

Surface Carbon Formation On Pt/ˠ-A12o3 From C3 And C4 Hydrocarbons Part Ii: Characterization Of Coked Samples, L.L. Mkayula

Tanzania Journal of Science

The total surface area, pore size distribution, metal surface area, particle size and topography of coked Pt/γ-1₂O₃ catalyst samples used in in part 1 of this series were measured and compared with those of a fresh catalyst. No significant changes in total surface areas of the coked catalyst was observed despite a high coke content in some samples. This is interpreted in terms of partial narrowing of mesopores that was confirmed by pore size distributions observations of high temperature coked samples. The platinum metal surface area of high temperature coked catalysts decreased with increase in temperature and …

On The Entropy Of Kiswahili, Luhanga M.L, T.G.B. Nyambo

Tanzania Journal of Science

Cover and King’s gambling approach to the estimation of the entropy of English is used to estimate the entropy of Kiswahili. Experimental results obtained show that Kiswahili has average entropy of approximately 1.76.

A Preliminary Chemical Survey Of The Salt Deposits And Evaporates Of Lake Balangida, Hanang District, Tanzania, N. Mwakoba, D. Mosha, K. Schrøder

Tanzania Journal of Science

Lake Balangida is a typical salt-and –soda lake sharing many common hydrochemical features with the twenty or so hypersaline dischargeless lake of the African Gregory Rift Valley (Dead Sea to Lake Malawi). Sulphate content is however, comparatively exceptionally high but the single most contrasting dissimilarity is the virtual absence of fluoride. In previous reports, we have presented findings on the chemistry of the lake brines and inflows. In the present work, the salt deposits and evaporated which cover the lake after desiccation during the September-December dry spell are chemically examined. Salt and soda appear to occur in separate locations; the …

Theoretical And Experimental Study Of Inlet Manifold Pressure Profiles Using Compensated Transducers, P Mtui

Tanzania Journal of Engineering and Technology (TJET)

Computer simulation and experimental findings on single cylinder four-stroke cycle engine were done with a view of getting more realistic inlet manifold pressures. Since there is a direct relationship between the inlet pressure profiles and the volumetric efficiency of the engine, then there is a possibility of utilizing the knowledge of these profiles to enhance better engine air flow characteristics and hence improvement of engine performance.

The simulation program is based on hometropic process with constant specific heats where the results were validated using experimental findings of the engine with varying engine speeds.

Experimental results are obtained by measuring manifold …

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 …

Control System Design Program Based On Cascade Compensation, Fredrick Ishengoma

Tanzania Journal of Engineering and Technology (TJET)

CAD is becoming more widely accepted in the design and analysis of control systems. A program has been developed for analyzing single-input single-output linear time-invariant control system. The application of the progranl for frequency domain design of cascaded phase lead and phase lag coinpensators is briefly discussed. Two examples to illustrate the program are presented.

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

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

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

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.

Absorption Of Nitrogen Oxides Into Sodium Hydroxide Solution In A Packed Column: Effect Of Gas Flowrate And Temperature, J Katima

Tanzania Journal of Engineering and Technology (TJET)

The effect of gas flow rate and temperature on the absorption rate of nitrogen oxides (NO ) and column absorption eff iciency has been studied using a 2M goåium hydroxide (NaOH) solution in a packed The absorpt ion process was carried out at atmospheric column. pressure, with NOV concentration ranging between 150 and 10000 pp:tt, NO/N02 ratio of O and 1 iquid flow rate of O .8 1/ min. The gas flow rate was varied from 20 to 60 1/17 in and the temperature from 25 to 45 c. It was found that Ehe column absorption efficiency increases with decreasing …

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 …

Surface Resistivity Of Human Skin In Tropical Environment, Jan Strojny

Tanzania Journal of Engineering and Technology (TJET)

Human skin surface resistivity may innuence the decay processes of electrostatic charges in computer and control rooms and significantly contribute to electric shock hazards conditions. High temperature and humidity of tropical environment can significantly affect working conditions of operating personnel, resulting also in the change of electric resistance of the skin. Fast industrialization and introduction of Inodern electronics in the coast area of East Africa is connected with the increase of electromagnetic interferences and hanrds arising from electrical and electronic laboratories and control instrumentation of industrial plants. To meet the requirements for protection of equipment and personnel, knowledge of human …

Energy From Biomass: Combustion And Gasification, G John

Tanzania Journal of Engineering and Technology (TJET)

Some fundamental facts of the combustion Of BIOMAS are outlined and di scussed . It is suggested that these provide guidelines for rhe development Of successful practical combustors. Furthemore, a realisation Of energy conversion from the same in gasfier is presented.

Nn Investigation Of Nitrogen Oxide Abscwption In Packed Columns, J Katima

Tanzania Journal of Engineering and Technology (TJET)

An experimental study was carried out on the performance of a packed column to study the absorption mechanism of nitrogen oxides (NOx). Two packed columns were set up, one with wall wiper rings to reduce wall effects and one without. Both columns were packed with stainless steel lessing rings and operated at fixed gas and liquid flow rates (40 and 8 L/min, respectively), atmospheric pressure, temperature (25°C), and sodium hydroxide concentration (8% w/w). The NOx (NO₂ and N₂O₄) equilibrium concentration and feed concentrations of up to 7000 ppm were used. The results indicated improved performance in the column with wall …

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

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 …

Density Measurement For Corrosive Solutions At Elevated Temperatures, Kimweri, H

Tanzania Journal of Engineering and Technology (TJET)

In this work, apparatus for measuring densities of corrosive solutions at high temperatures was developed and used. Densities of dilute aqueous sulphuric acid solutions, containing different amounts of zinc and iron salts were measured at temperatures up to 185°C. In view of the good agreement between consecutive measurements for each solution and the density of water obtained by using this apparatus with that given in literature, for all experiments, the apparatus is recommended to be used for measuring densities of corrosive solutions at high temperatures.

Electrical Equivalent Method For The Calculation Of Vibrations In Transformers, D Chambega

Tanzania Journal of Engineering and Technology (TJET)

Noiselevel calculations may be done using an electrical equivalent method. So far a single mass and a double mass vibrating system may easily be represented by equivalent electrical circuits which are in turn useful for analysis. Multimass vibrating systems like transformers do not have straightforward methods which can enable analysis of noiselevels. This paper attempts to develop such a method by extending the method applicable to a double mass vibrating system. Then the validity of the method is tested using a transforme

Factors Affecting Capacity Utilization In Industries: Hierarchical Analysis, M Victor

Tanzania Journal of Engineering and Technology (TJET)

This paper provides a hierarchical analysis of the factors affecting capacity utilization in Tanzanian industries. Several factors were identified and sent to randomly selected industries in Tanzania for ranking. The collected data was summarized and analyzed. The analysis made use of a known procedure, the 'Analytical Hierarchy Process' (AHP). The final results shows a ranking of the factors, on various hierarchical levels as to their percentage contribution in lowering the capacity utilization.

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

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" …