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1994

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Design Approach For Small Scale Continuous, Steady State Plants, O Kaunde Dec 1994

Design Approach For Small Scale Continuous, Steady State Plants, O Kaunde

Tanzania Journal of Engineering and Technology (TJET)

One of the major steps in the design of a process plant is development of an appiopriate flowsheet. At this step, the technical solutions may be con- sidered in relation to the social and economic factors. In this paper, guide- lines for developing a flowsheet for continuous, steady State process in a developing country environment have been proposed. To illustrate the pro- posed guidelines, a case study involving design of an ethanol distillation plant has been used.

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Experimental Investigation On The Use Of Native Biomass As Biosorbents For Metal Pollutant Removal, R Litto Dec 1994

Experimental Investigation On The Use Of Native Biomass As Biosorbents For Metal Pollutant Removal, R Litto

Tanzania Journal of Engineering and Technology (TJET)

Waste water treatment is a perrnunent task. Many novel techniques have emerge in recent years and one of them is using biomass in removing heavy- metals. In this research screening and preliminary optimization experi- ments have identified different types of abundant biomass which can accu- mulate heavy metals such as Fe3*, C03•, Cu2+ and ftvm effluent. Cystoseira Myrica has a high uptake ofCr3+ while Sargassum Polycystum has been found to have a high uptake 0fFe3+. Observed biosorption kinet- ics shows rapid initial stage, followed by slower second stage and the amount of material adsorbed increases linearly as its concentration in …

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Improved Heat Transfer By Means Of Steam Injection In A Shell & Tube Heat Exchanger, O Kaunde Dec 1994

Improved Heat Transfer By Means Of Steam Injection In A Shell & Tube Heat Exchanger, O Kaunde

Tanzania Journal of Engineering and Technology (TJET)

When designing a heat exchanger; one aims at attaining high heat transfer rates SO as to minimise heat transfer area and therefore the overall cost. This paper presents a method of improving the overall heat travsfer coef- ficient of a conventional shell and tube heal exchanger. The method in- volves injecting steam into the process fluid as it enters the heat exchanger thus effecting mixing of fluid as it travels along the exchanger Tests car- • ried out using this technique showed a significant increase in the overall heat transfer coefficient values.

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Model For Complete Drawdown Of Floating Solids In Stirred Tank Reactors, J Mmbaga Dec 1994

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.

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A Fracture Kinetics Analysis Of Hydrogen Embrwi'lement, J Mshana Dec 1994

A Fracture Kinetics Analysis Of Hydrogen Embrwi'lement, J Mshana

Tanzania Journal of Engineering and Technology (TJET)

In studies on stress corrosion cracking caused by hydrogen embrittlement of metals, it has been observed that within the high remperature range rhe Armenius activation energy is negative. This is quite unusual Since ther- mall)' activated crack g.'vwth processes are controlled by positive appar- ent activation energy. The unders/auding of this effect is of inleavst to design and maintenance engineers. The study demonstrates, with a syn- thesis method, a physically rigorous and rational kinetics Of thermally activated processes of some aspects ofenvironment assisted crack growth. It is show that the observed crack growth behavior may be described by single barrier …

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Measurement Of Dust Resistivity And The Effect Of Filter Operating Parameters On Its Value, S Issangya Dec 1994

Measurement Of Dust Resistivity And The Effect Of Filter Operating Parameters On Its Value, S Issangya

Tanzania Journal of Engineering and Technology (TJET)

Methods of measuring electrical sensitivity of a dust layer have been outlined and the porous electrodes cell was used to measure the electrical resistivity of a dust layer and to determine the influence of various parameters. Dust layer thickness and applied voltage had no influence. Resistivity depended on particle size, packing density, temperature, and air relative humidity. Glass beads and limestone powders of different mean particle sizes were used. Temperature was varied from 20–100 °C and air moisture ranged from dry to near saturation. The results may help in understanding the performance of electrically enhanced fabric filters, which are influenced …

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Solar Heater For Curing Tobacco Part I: Overview And Theory, J John Dec 1994

Solar Heater For Curing Tobacco Part I: Overview And Theory, J John

Tanzania Journal of Engineering and Technology (TJET)

This is two parl paper. In part one of the papet; an overview on the use Of packed beds on heat collectors To be used in natural convection systems is presented. A brief theoretical background and literature review has also been presented. Theoretical analysis and performance equations are pre- sented in detail. Two zypes of absorbers are proposed for investigation. The firs,' one will be with flow below the absorber and the other with flow "'through " {he absorber. These shall be compared with the conventional flat plate collector. For comparing the performance, packings of different materials, shapes, and sizes …

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Evaluation Of The Influence Of The Magnetic System In Relays, D Chambega Dec 1994

Evaluation Of The Influence Of The Magnetic System In Relays, D Chambega

Tanzania Journal of Engineering and Technology (TJET)

The paper evaluates the influence of different cores on the performance of relays. In particular two types ofc-cores, all made from IOW quality mag- netic steel, are considered. The two cores, one butt-constructed and the other interleaved, are mathematically modelled and the tesults are analyzed and obtained experimentally. Then the two sets of results are compared with those ofa c-shaped core of excellent magnetic material with the aim of qualifying the influence of the core material. It is observed that the method of constructing the core also influences the performance.

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Power Shedding Experiences And Lessons In A Township, Alexander Kyaruzi Dec 1994

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.

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Polymer Supported Z-N Catalysts For C2h4-Polymerization,I: Development Catalyst Preparation Method, S Mteza Dec 1994

Polymer Supported Z-N Catalysts For C2h4-Polymerization,I: Development Catalyst Preparation Method, S Mteza

Tanzania Journal of Engineering and Technology (TJET)

Substantial improvement of low sensitivity pressure transducers aiming at obtaining a more realistic output signal is discussed. The output signal direct from these transducers has deficiencies of amplitude attenuation and phase lag, thus the measured values are not necessarily the true in- stantaneous values. In order to correct for such shortcomings the unit step response of these transducers is also studied experimentally. A math- ematical model is established based on the experimental results to build up a compensation circuit which is then included in the instrumentation setup to eliminate these deficiencies. The effectiveness of the compensated transducer is demonstrated by …

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Application Of Improved Pressure Transducers For Pressure Measurements, P Mtui Dec 1994

Application Of Improved Pressure Transducers For Pressure Measurements, P Mtui

Tanzania Journal of Engineering and Technology (TJET)

Substantial improvement of low sensitivity pressure transducers aiming at obtaining a more realistic output signal is discussed. The output signal direct from these transducers has deficiencies of amplitude attenuation and phase lag, thus the measured values are not necessarily the true in- stantaneous values. In order to correct for such shortcomings the unit step response of these transducers is also studied experimentally. A math- ematical model is established based on the experimental results to build up a compensation circuit which is then included in the instrumentation setup to eliminate these deficiencies. The effectiveness of the compensated transducer is demonstrated by …

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Influence Of Arc Discharge Duration On Turbulent Mass Burning Rate, E Mushi Dec 1994

Influence Of Arc Discharge Duration On Turbulent Mass Burning Rate, E Mushi

Tanzania Journal of Engineering and Technology (TJET)

The influence of arc discharge duration on turbulent mass burning rate was investigated for turbulent r.m.s vglocities of u '=1.73 m/s and u'=4.5 nfs. Methane air mixtures were used at equivalence ratios ranging from 0.83 to / .25. Flame size was obtained through schiieren photography while the intensity Of CH chemiluminescence emissions was used to measure mass burning rate. A variable spark duration unit was used for ignition sparks and all the experiments were done in a fan stirred bomb. Discharge duration has no effect when the equivalence ratio is I. For higher values longer duration inoeases the burning rate …

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Optimum Geometrical Parameters For Prismatic Folded Plate Roofs: System- Atic Search Approach, N Mwitta Dec 1994

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. …

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College Voice Vol. 18 No. 10, Connecticut College Nov 1994

College Voice Vol. 18 No. 10, Connecticut College

1994-1995

No abstract provided.

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College Voice Vol. 18 No. 7, Connecticut College Oct 1994

College Voice Vol. 18 No. 7, Connecticut College

1994-1995

No abstract provided.

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Commencement Convocation Exercises - August 1994, Prairie View A&M University Aug 1994

Commencement Convocation Exercises - August 1994, Prairie View A&M University

Commencement and Convocation Exercises

No abstract provided.

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President Bizimungu's Inaugural Address, Us Embassy Rwanda Jul 1994

President Bizimungu's Inaugural Address, Us Embassy Rwanda

David Rawson Collection on the Rwandan Genocide

President Bizimungu's Inaugural Address

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Pulping Of Sisal Fibres: Effects Of Chemical Concentration, Na-Zs03/Na2c03 Ratio And Fibre To Chemical Ratio, J Katima Jun 1994

Pulping Of Sisal Fibres: Effects Of Chemical Concentration, Na-Zs03/Na2c03 Ratio And Fibre To Chemical Ratio, J Katima

Tanzania Journal of Engineering and Technology (TJET)

This paper reports on pulping of hard fibres extracted from the leaves Of agave sisalana using sodium sulphite buffered with sodium carbonate as pulping chemical. The cooking was carried Out at 1680Cfor a cooking period of 6 hours, with varying chemical concentration, sodium sulphite to sodium carbonate ratio and fibre to chemical ratio. The results show thar boll! the pulp yield and pulp viscosity decæase with increasing chemi- cal concentration, whereas Kappa number of pulp decreases to a limit of about 16.45. Brightness increases significantly with an increase in the ra- rio of Na2S03/Na2C03. The pulp yield obtained indicated the …

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Electricity Consumption Patterns In Domestic House Holds, H Kadete Jun 1994

Electricity Consumption Patterns In Domestic House Holds, H Kadete

Tanzania Journal of Engineering and Technology (TJET)

Electricity tariff increases from 1988 to 1992 are presented. They are Compared with salaries paid to parastatal workers over the same period. Monthly expenditures on electricity are also presented. Electricity con- sumption profiles have been recorded. The typical end use electrical ap- pliances for each household category have been identified. About 69% of electricity is used for cooking in high demand households. In medium demand households electricity used for lighting dominates ar about 49%. Measurements indicate a 3 peak power consumption profile for domestic dwellings. Voltages of 180V were recorded instead of the expected 230V nominal. Power factor is nor …

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Hazards Inherent In The Use Of Electricity, Alexanda Kyaruzi Jun 1994

Hazards Inherent In The Use Of Electricity, Alexanda Kyaruzi

Tanzania Journal of Engineering and Technology (TJET)

This paper describes hazards associated with thc use of electricity, empha- sis is given to hazards due to electric shocks. A survey carried Out by the author indicated that 68.5 % of all reported accidents and 55.3 % of all fatal accidents are due to people Coming into contact with normally non current carrying metallic parts. The necessary conditions which need to bc present in an electric system for electric shock to occur are described. How the human body responds to Various severity of electric shock is dis- cussed. Possible solutions, and how to prevent or minimise the effect Of …

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Regionalization Of Hydrologic Information In Tanzania (Low Flows), Onyekwuluje C Jun 1994

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 …

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Influence Of Turbulence On Methane-Air Flame Speed, E Mushi Jun 1994

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.

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An Alternative Method Of Interfacing A Dc Motor To A Microprocessor For Mo- Tion Control, M Selekwa Jun 1994

An Alternative Method Of Interfacing A Dc Motor To A Microprocessor For Mo- Tion Control, M Selekwa

Tanzania Journal of Engineering and Technology (TJET)

A Simple and cheap alternative method Of interfacing a permanent mag- net dc motor to a motion control using switch- ing transistor motor drivers is presented. This method involves the use Of very few transistor-transistor logic (TTL) devices and a 555 timer to pro- duce a pulse width modulated (P WM) signal which is required by the mo- ror driver. The motor driver in this case should be of an H-bridge type. Like other methods currently in use, it relieves the MPU of all timing func- tions which are necessary in the generation of P WM signals. The present method, …

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Quality Problems Facing Tanzanian Industrial Firms, M Msafiri Jun 1994

Quality Problems Facing Tanzanian Industrial Firms, M Msafiri

Tanzania Journal of Engineering and Technology (TJET)

This paper reports on the results of a study of quality problems facing Tanzanian industrial firms. The results show that Tanzanian firms do not set goals with respect to quality and quality management, thus their qual- ity performance is generally poor. A Ithough there are a number of opera- tional problems constraining the companies, the main problems lie with the internal management of the quality function. Extensive ideas and sug- gestions for improving the performance of the quality function are given.

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Measurement Of Dust Resistivity And The Effect Of Filter Operating Parameters On Its Value, Allan Issangya Jun 1994

Measurement Of Dust Resistivity And The Effect Of Filter Operating Parameters On Its Value, Allan Issangya

Tanzania Journal of Engineering and Technology (TJET)

Methods sed to measure the electrical resistivity of a dust layer and to determine the influence of various parameters. Dust layer thickness and applied voltage were found to have no influence. Resistivity depends on particle size, packing density, temperature, and air relative humidity. Glass beads and limestone powders of different mean particle sizes were used. Temperature was varied from 20–100 °C and air moisture ranged from dry to near saturation. The findings may help in understanding electrically enhanced fabric filters, whose performance is influenced by the resistivity of the collected dust layer.

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Optimal Capacity Allocation Truck Industry In Tanzania:A Case Of National Transport Corporations(Ntc), R Mgaya Jun 1994

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 …

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Dual Versus Single Spark Plug: A Critique, I Mshoro Jun 1994

Dual Versus Single Spark Plug: A Critique, I Mshoro

Tanzania Journal of Engineering and Technology (TJET)

Dual spark plugs are occasionally employed on certain modern Spark lg- nited (S') engines, viz lean burn engines. Their benefit has generally been noticed in the operating conditions whenfuel-air mixture is very lean, or when a larger proportion of EGR has been employed, or during the part load conditions and so on. An extensive literature survey has indi- cared an interesting spectrum of reasons for gains due to the dual spark plug. A consistent explanation is found to be missing which can describe the behaviour of the engines with single versus dual spark plugs There are quite "few researchers who …

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Suitability Of The Present Strategic Information Technology Planning (Sitp) Methodologies To The Developing Countries, A Victor Jun 1994

Suitability Of The Present Strategic Information Technology Planning (Sitp) Methodologies To The Developing Countries, A Victor

Tanzania Journal of Engineering and Technology (TJET)

The needfor strategy formulation, or in general terms strategic planning, for IT is considered as one of the most important aspects of IT manage- ment. To this end, there are a number of IT strategy formulation method- ologies world-wide. These methodologies were developed over a span of time, starting from mid 1960's when IT use started to become a serious issue in the developed countries, and continued with the trends in IT de- velopment and use, as was applicable in those countries. Morc recent of the methodologies were developed through improvements on earlier ones, and based on the new challenges …

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Sixteen Um Students Set For Foreign Exchange Programs, University Of Montana--Missoula. Office Of University Relations Jun 1994

Sixteen Um Students Set For Foreign Exchange Programs, University Of Montana--Missoula. Office Of University Relations

University of Montana News Releases, 1928, 1956-present

No abstract provided.

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Essay—Sub-Saharan Africa: Economic Stagnation, Political Disintegration, And The Specter Of Recolonization, Jon H. Sylvester Jun 1994

Essay—Sub-Saharan Africa: Economic Stagnation, Political Disintegration, And The Specter Of Recolonization, Jon H. Sylvester

Loyola of Los Angeles Law Review

No abstract provided.

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