Digital Commons Network^™

Service And Network Modeling For Implementation Of Powerline Remote Monitoring Of Electrical Power Metering In Tanzania, J Anatory

Tanzania Journal of Engineering and Technology (TJET)

The conventional metering. pyepa.vmen,' and estimates have been used in power utilities industries. The svslen,'s hare experienced many problems such as power tampering, bill tampering, ./åiluve ro receive invoices by poner unlity customers and so on. Different technologies have been investigated To overcome the problems and recently it has been realized that remote 'nonitoring sysle•ns through powerline channel is a solution offhese problems in Tanami". However. 'he powerline network has been used for electrical power IO use i,' for implementation of remote monitoring: network must be setup and has to be modeled to accommodate communications. The contribution has analyzed 'he …

Load Flow Solution For Three-Phase Mv Radial Distribution Connected Network Supplying Different Line Topologies, B. J. Kundy

Tanzania Journal of Engineering and Technology (TJET)

In this paper, a load flow solution for the Medium Voltage (MV) three-phase radial distribution in delta-delta (Δ–Δ) connected network supplying different line topologies such as three phase, phase to phase and single-wire earth return (SWER) networks is presented. The general voltage related network equations are developed using Kirchhoff’s voltage and current laws. Development of a solution to the load flow analysis applying the developed general voltage related network equations is proposed in order to evaluate the network voltage profile. Various numbers of arrays are developed for the identification of the network under study. The proposed method is a new …

Simulation Of The Communication Process In A Pin Mill, Ambrose J. M. Itika

Tanzania Journal of Engineering and Technology (TJET)

Prediction of the performance of comminution equipment by mathematical models and simulation poses a great challenge to the chemical engineer. This paper describes the simulation of grinding results obtained using an impact mill. Single particle results have been used to generate breakage and selection coefficients that were used for the evaluation of the model. Results have shown that simulation model is in good agreement with the experimental data obtained at a circumferential speed above 60 m/s. At lower speeds, the models shows only partial agreement in the middle particle size ranges. The application of the model is therefore limited for …

Derivation Of An Expression That Defines The Pulling Forces In Relays With Small Operating Gaps, D. J. Chambega

Tanzania Journal of Engineering and Technology (TJET)

This paper derives an expression that defines magnitude of the pulling force developed in relays with small operating gaps, that is, when the length of the operating gap in between the yoke and the armature is small as compared to the area of the poles at the yoke. To obtain the expression, saturation of the core material is not considered. Results from the expression are then compared with those obtained experimentally. The comparison is found to deliver acceptable accuracy.

Analysis On Possible Solution To Decreasing The Effect Of Non-Uniform Air-Gaps Due To Rotor Eccentricity In Asynchronous Machines, Dominic Chambega

Tanzania Journal of Engineering and Technology (TJET)

Rotor eccentricity introduces non-uniformity of the airgap which in turn causes additional frictional torques and losses in addition to establishing a uni-directional pulling magnetic force which is disastrous to the machine. This paper analyses the extent of the damage to the machine due to non-uniformity of the air-gap and proposes increasing the number of poles as a possible solution to arrest the effect. It is found through the analysis that as the number of poles increases the effect of eccentricity decreases.

A Comparative Application Of Telecommunication Traffic Forecasting Methods To A Backbone Link In Tanzania, M. L. Luhanga

Tanzania Journal of Engineering and Technology (TJET)

In this paper various mathematical models to characterize and forecast telecommunication traffic time series traffic have been applied, and the ranges of validity of the models are determined by comparing them with measured traffic data using the measurement errors criteria method which resulted into the superior model. Based on this model the ARIMA (0,2,1) model for smoothed data, the traffic forecast findings show that by the year 2006, the traffic demand will exceed the current installed capacity of 140 Mbps in the Tanzania Telecommunications Company Limited (TTCL) network along the major link between the Dar es Salaam and Dodoma backbone …

A Study Into Lack Of Product Innovation And Business Techniques At The Tricycle Workshop And Rrs Lessons To Small Companies, E Elias

Tanzania Journal of Engineering and Technology (TJET)

A study was carried out at the Tricycle Workshop (TW) which was facing the problem of !ack of orders and therefore stagnation Of business. The objective of the study was to find out reasons for this situation and to propose possible remedial solutions. The study was conducted using the principles of the Product Innovation process where internal and external issues related to the business Of the company were investigated for information. Analysis Of information obtained indicated that the bad situation of the TW had mainly been caused by the nature of the tricycles-supply system whereby users (disabled persons) are unable …

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 …

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 …

Trends Of Microcomputer Technology In Developing Countries, With More Focus On Tanzanian Experiences: Achievements And Problems, Satoki Mahenge

Tanzania Journal of Engineering and Technology (TJET)

Trends of microcomputer technology in developing countries, including Tanzanian. is like a 'mixed bag' of achievement and problems. Although rhe technology has been available for many years in developed world, developing countries are responding to it differently due to differences in political and economic policies. Some countries have acrimonious policies on the technology, some not. There are countries which utilize fully the technology in work places and others are still at dilemma on the importation of the technology due to what is 'claimed to be a weak economy in the presence Of many other pressing needs'. Other countries seem to …

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.

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.

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.

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 …

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, …

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 …

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 …

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.

Practical Aspects In Sensing Vrm Magneti- Sation Characteristics For Rotor Position Detection, N Mvungi

Tanzania Journal of Engineering and Technology (TJET)

The detection of rotor position (stator/roror poles overlap) in a variable reluc- tance motor using the dependence of permeance on rotor position is the core of the effort to eliminate the need of a physical position sensor in the rotor shaft in the positional feedback operation of the motor. The reliability of the whole proc- ess Of eliminating the need of a physical sensor rests squarely On the ability to measure the instantaneous permeance ofa phase when the motor is in operation and at stand still. This paper presents an experimental investigation on the in- triguing problems of obtaining repeatable …

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 …

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.

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 …

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.

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.

Computation Of Frequency Characteristics Of Lumped-Element 3 Db Branch Line Directional Couplers, H. R. Mgombelo

Tanzania Journal of Engineering and Technology (TJET)

An analysis of the 3 dB lumped-element branchline directional coupler constructed using L-C and T networks is given. Matrices of lumped element capacitances and inductances in the form of low and high pass filters are equated to the matrices of the distributed element transmission lines at the centre frequency of operation, as a result of which design equations are derived. Using even and odd modes of excitation, frequency characteristics of the directional couplers are computed and compared to those of the coupler constructed using distributed element transmission lines.

The Design Of A Resonant Post Waveguide Filter, Ramjee Prasad

Tanzania Journal of Engineering and Technology (TJET)

A seven stage, quarter-wave coupled, single post, resonant cavity type waveguide filter has been studied. The posts are placed according to the Tchebyscheff distribution. The filter is designed and fabricated to meet the following specifications: Centre frequency: 9.31 GHz, Number of stages = 7, 3-dB bandwidth = 300 Mhz, Ripple tolerance in the passband = 0.5 dB. The frequency behaviour of this filter has been experimentally studied and is in close agreement with the specifications.

Gain Margin And Phase Margin Interrelationships, M Luhanga

Tanzania Journal of Engineering and Technology (TJET)

The gain margin and the phase margin Of a control SY Stem are important parameters in the determination of the relative stability of control system. In this paper We derive general interrelationships between these parameters.

The Mean Return Time To A State For A Markov Chain Representing In Telephone Conversations, M Luhanga

Tanzania Journal of Engineering and Technology (TJET)

The mean return time to a state for a Markov chain representing N off-hook telephone conversations can be obtained by using ergodic flow rates [1] or renewal theory [2]. In this paper it is shown that the same result may be obtained by using no more knowledge of stochastic processes than the solution of time-homogeneous Chapman-Kolmogorov equations.

An Electro Hydrodynamic Study Of The Negative Corona Electric Wind, Henry Thadei Kadete

Tanzania Journal of Engineering and Technology (TJET)

The velocity of corona generated electric wind is measured. From the velocity profile mass movement and electrokinetic conversion efficiencies are deduced. High speed schlieren photographs illustrate the form of the velocity distribution function as well as its high degree of turbulence.