Tanzania Journals of Engineerin

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					Tanzania Journals of Engineering and Technology (TJET)
Vol 1(1) 2006

STUDY ON VORTEX FORMATION IN THE POURING BASIN
BY DIRECT OBSERVATION
J. Runyoro
Department of Engineering Materials, University of Dar es Salaam
P.O. Box 35131, Dar es Salaam Tanzania
ABSTRACT
lthough 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 be taken for granted and this is, perhaps why the subject
has received relatively little scientific attention. Mathematically a derivation is known but
it does not take into consideration variables such as shape and size of the container or the
draining orifice. Experiments were carried out using containers of different shapes and
sizes, orifices of different shapes and sizes placed at different points in the container. The
minimum head in the container that prevents the formation of vortex has been determined
and is the function of container and orifice geometry.
Keywords
Free vortex, pouring basin, orifices, film forming alloys, critical height, free surface

SOCIO-ECONOMIC IMPACTS OF COMPUTER VIRUSES
IN TANZANIA
M.A.M. Victor and J.L. Kamara
Department of Engineering Management and Entrepreneurship
Faculty of MECHE, UDSM P.O. Box 35131, DSM
mmvictor@uccmail.co.tz

ABSTRACT
his 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 such as TTCL and VODACOM.
Other institutions where data was collected included the higher learning institutions such
as UDSM, DIT & IFM, Government institutions such as the Government Chemist, and
COSTECH and Non- governmental institutions such as REPOA and ESRF. After data
analysis, it was found out that majority of the surveyed organisations were aware of CVs
and about half of them employ client-server technique to successfully deal with the
threat. These organisations spend between US$ 12,000 to 40,000 per year to deal with
CVs. This cost is mainly for paying licence fees for anti-viruses and for data back-ups.
Some organisations rely on pirated anti-virus which are unreliable and in most cases lead
to disasters and losses of data and production time. It was concluded that CVs control
should be given the highest priority to all ICT users. Also a policy on CVs should be
well written and be instituted. Knowledge exchange on Anti-viruses’ configuration
should be enhanced among System Administrators within Tanzania. CVs control training
should be done frequently to all workers. The use of an inert operating system such as
Linux to control the spread of CVs should be promoted for use in workstations and for
newly established organizations. Budget for CVs control should be considered at early
stages.
Key Words: ICT, Computer viruses, Anti-viruses

THE DECOMPOSITION KINETICS OF SOLIDS
THERMODYNAMIC EVIDENCE FOR THE ENTHALPY DRIVEN COOLING
OF
REACTION ENVIRONMENT PART 2
Akwilapo, L. D., Kyobe, J. M. P and Buchweishaija, J.
Chemistry Department, University of Dar es Salaam,
P.O. Box 35061, Dar es Salaam, Tanzania
ABSTRACT
he analysis of non-isothermal kinetic data for the decomposition of calcium carbonate,
CaCO3 (s) CaO (s) + CO2 (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 H = 179.33 kJmol-1 estimated from this work for the dissociation of
CaCO3 is in agreement with H = 179.17 kJmol-1 derived from the enthalpies of
formation of the reaction components. The results support the mechanism suggesting heat
transport to be the rate-limiting step. Keywords: Solid-state decomposition, kinetic
parameters, thermodynamics.

SUITABILITY OF CRUSHER-DUST AS MASONRY
CONSTRUCTION MATERIAL
Dr-Ing. John K. Makunza
Department of Structural Engineering
University of Dar es Salaam
ABSTRACT
rusher dust generated at Kunduchi quarries in Dar es Salaam during aggregate crushing is
counted as a waste material, and some times it is disposed away or sold at a cheap price
of not more than a quarter of that of sand. A study on the use of the crusher dust as a
building material has been carried out in which samples were collected and analyzed for
grading (sieve analysis). In additional to that, other samples were stabilized with a small
amount of cement, from which bricks were produced and tested for compressive strength.
Other bricks were bonded together using mortar which had the same ratio of cement to
crusher dust as that which was used for manufacturing the bricks. Then both the bricks
and the walls were tested for compressive strength. The results obtained from sieve
analysis as well as compressive strengths have shown that the crusher dust masonry is a
suitable building material which leads to lower cost
of the walls if compared to concrete blocks.
Key words: Crusher dust, grading, mould, bricks, mortar, strength.

EFFECTIVENESS OF HOT ISOSTATIC PRESSING ON HEALING
OXIDE FILM DEFECTS IN CAST ALUMINIUM ALLOYS
C. Nyahumwa
Department of Engineering Materials, University of Dar es Salaam,
P.O. Box 35131, Dar es Salaam, Tanzania

ABSTRACT
ot isostatic pressing (hipping) of cast aluminium alloys is recognized as a means of
providing improved internal soundness and mechanical properties of the castings.
However, little is known about the limitations and potential benefit of the hipping process
to produce reliable aluminium alloy castings containing oxide film defects due to
turbulently filling of moulds. In this study, oxide film defects and fatigue lives of
turbulent filled unfiltered Al-7Si-Mg alloy castings have been characterised in as-cast and
hipped conditions to quantify the effectiveness
of hot isostatic pressing on healing oxide film defects in the castings. The average fatigue
life and fatigue life at 0.1 percent failure rate of Al-7Si-Mg alloy castings improve
substantially following hipping treatment that also reduces significantly the scatter of the
fatigue life data of the castings. This indicates that solid state hipping is a robust process
to de-activate oxide film defects in Al-7Si-Mg alloy castings in which transformation of
oxide film structure does promote the diffusion bonding across oxide film interfaces.
This, however, contrasts with the behaviour of oxide inclusions in Al- 10Mg alloy
castings in which magnesium oxide film, whose structure is stable and does not transform
during hipping, is possibly resistant to form effective bonding across the oxide film
interfaces.
Keywords: Oxide film defects; Hot isostatic pressing; Aluminium alloys; Diffusion
bonding.

COMPARISON OF TWO DIFFERENT TRANSPORT MODELS TO PREDICT
SEDIMENT TRANSPORT: SIMIYU RIVER, TANZANIA, CASE STUDY
Mwanuzi Fredrick
Water Resources Engineering Department, University of Dar es Salaam
Box 35131 Dar Es Salaam fmwanuzi@yahoo.com

ABSTRACT
his 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: SMS based
sediment transport is decoupled from the hydrodynamic module while SCALDIS is
coupled model where the hydrodynamic and transport are run in real time. Both models
were applied at the downstream section of the Simuyu River, which is located at the
southeast of Lake Victoria. The models were independently calibrated with a typical
flood year 1967/68 and then compared. Both model results indicate that the temporal
variability of total sediment deposition during a flood event was strongly tied to the
sediment inflow concentrations. The comparison of both model results indicates that
SCALDIS is easier to calibrate as compared with SMS based sediment transport. The
SMS modules require detailed information about a large
number of model parameters, which are difficult to obtain in remote areas. The
SCALDIS model is less input demanding, and the only sensitive parameter is the
Manning’s coefficient, which can be estimated based on expert knowledge and limited
field measurements.
Key word: SCALDIS, SMS, Model, Sediment transport, FRIEND/NILE, Hydrodynamic

OVERVIEW OF HYDRAULICS AND SIMIYU RIVER SEDIMENT INPUT
INTO MAGU BAY, LAKE VICTORIA, TANZANIA
Alfonse M. Dubi
Institute of Marine Sciences, University of Dar es Salaam
P.O. Box 668 Zanzibar, Tanzania
E-mail: dubi@ims.udsm.ac.tz

ABSTRACT
ake 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
using a GPS, Model Garmin 12. Suspended sediment concentrations were determined by
sampling the water, filtering and weighing the sediments. Data on rainfall and water
discharge were obtained from the Mwanza Meteorological office. Statistical analysis
shows that cumulative rainfall of 1043 mm and the respective discharges of 98.5 m3/s
have a return period of 5 years. A return period of 50 years is expected to have
cumulative rainfall of 1403 mm and dischargees of 156.7 m3/s. Concentration of
suspended particles was highest at the river mouth (1573 mg/l at station 1) and
exponentially decreased as one moves away from the river (0.9 mg/l at station 8, a station
that was
most off-shore from the river mouth). Also, turbidity was higher towards the river and
decreased as one moves away from the river mouth. In the first half a kilometre
longitudinally from the river mouth, most of the suspended sediment has been deposited
its concentration is attenuated exponentially as Cs/Cso = e- x, where Cs is suspended
sediment concentration at distance x from the river mouth and Cso is concentration at x =
0 (at the river mouth) and k = 2.1 is the
attenuation coefficient. Both surface and bottom currents exhibited the same trend as
sediment concentration. At the mouth of the river, the surface and bottom current are
northward. In the first half kilometre from the river mouth, the current speed has been
strongly attenuated from 0.54 m/s to 0.07 m/s. From there onwards, the current speeds are
reversed, almost flowing in the opposite direction of the river flow. Simiyu River is a
major sediment contributor to the bay ranging from zero on days when there is no water
discharge to about 20,000 tons/day in the observed period. It is recommended that a
comprehensive and long-term study to cover all river sediment input into the lake be
undertaken.
Keywords: Lake Victoria, Magu Bay, hydraulics, sediment transport

GASIFICATION KINETICS OF ULTRAFINE COAL CHAR OXIDATION
IN FLAME REACTIONS
G.R. John and I.S.N. Mkilaha
University of Dar es Salaam, Department of Energy Engineering
P.O. Box 35131, DSM, Tanzania, Email: grkjohn@uccmail.co.tz

ABSTRACT
ulverized 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 4µm diameter graphite particle burning in
methane – air flames at a pressure of 0.160 atm. The low pressure not only ensured good
spatial resolution of the flame structure but it also ensured that the graphite reaction rate
was chemically
controlled. Comparable values from prediction and measurements were observed and
were explainable in terms of the presence of reactive flame radicals O, OH, and H in
controlling oxidation aided by the catalytic radicals attack by molecular oxygen. The
primary oxidation product from the kinetics is CO. This is simultaneously coupled to a
detailed multi-step gas phase
kinetic mechanism in the oxidation for CH4 – air flames. For lean flames, the available
CO in the presence of the reactive radicals enhances reactions with the effect of
enhancing the associated heat release rate. This contributes to the observed enhanced
burning velocities in these flames. For rich flames, because of the limited amounts of O2,
the catalytic effect is impaired and thus reduces the char oxidation rate and thus reduces
the burning velocity of the propagating flame.

INVESTIGATION OF THE STABILITY OF ENGINE – GOVERNOR
SYSTEM OPERATED AT LOW SPEEDS
Cuthbert F. Mhilu and Iddi S.N. Mkilaha
University of Dar es Salaam, Department of Energy Engineering
P.O. Box 35131, Dar es Salaam, Tanzania
E-mail: cfmhilu@hotmail.com

ABSTRACT
uring 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. In 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 on the engine operation condition, use has been made of a
mathematical model that incorporates the engine, governor and a tachometer. A
simulation was conducted by solving the system’s differential equations using a fourth
order Runge-Kutta
numerical integration method written in C code computer programs. The results obtained
show the stability of the engine- governor system operated at low speed to be stable.
When the engine was subjected to some parameter variations the engine showed some
sign of instability occurring at increased disturbance intensities. Based on the obtained
results an enhanced knowledge has been obtained giving an indication on how the
existing mechanical engine speed governors
design features could be improved to achieve engine stability at low speeds.
Keywords: Engine, Governor, Stability, Speed, Control

ENVIRONMENTAL IMPACT OF WETLAND RESOURCES UTILIZATION
IN SIMUYU BASIN, TANZANIA
Shadrack Mwakalila
Department of Geography, University of Dar es Salaam
P. O. Box 35049, Dar es Salaam, TANZANIA
Tel: +255-713-271299; Fax: +255-22-2410393
E-mail: smwakalila@yahoo.com

ABSTRACT
here is a growing appreciation of the natural functions of wetlands, and the values and
different forms of uses that humans attach to them. Wise use and special conservation
strategies are therefore needed in order to sustain their productivity. Wetlands are one of
the most fruitful areas of archaeological research, and they are the ideal setting in which
to study the interactions between physical processes and human actions that encapsulate
and exemplify many of
the themes of man’s impact on his environment. But all these beneficial functions of
wetlands seem to be in danger of being lost to draining and in-filling. This paper attempts
to address how the Geographic information systems (GIS) and remote sensing techniques
could be used to unveil land use patterns that have resulted in degradation of the
wetlands in Simuyu basin in Tanzania. The analyses drawn upon the use of remote
sensing data for assessment of wetland resources: land, forestry, agriculture settlement,
grazing, and wetland management, and highlight the physical and technical
characteristics of the resource. Landsat images used for vegetation mapping and land
cover change study were at a temporal scale of a 10-year interval from 1973. 1973, 1985,
1995, and 2005. Landsat satellite images were used to inform landscape qualities over
broad areas under the study area. The satellite sensors being used cover the visible and
infra-red (VIR) spectrum up to the microwave region of the electromagnetic spectrum
and are being based on a single sensor approach or sensor combination that fulfills a
minimum requirement for practical land cover mapping and inventory purposes (e.g.
forest and non-forest areas, wetland and dryland, varying land use density, dominant
species (crop) composition, flood prone areas and impact of human activities). Both the
technical capabilities and the potentials
of the data are presented in correlation with the existing ground conditions.

Vol 1(2) 2007

TOWARDS EFFECTIVE ONLINE LEARNING IMPLEMENTATION IN
TANZANIAN HIGHER LEARNING INSTITUTIONS: OBSTACLES,
CHALLENGES AND OPPORTUNITIES
Victor, M.A.M. and Lufungulo, P.S. M.
Department of Engineering Management and Entrepreneurship
Faculty of MECHE, CoET, UDSM
P.O. Box 35131, DSM
E-mails: mmvictor@uccmail.co.tz and machibya@uccmail.co.tz

ABSTRACT
This paper identifies and discusses several influential factors as well as opportunities,
associated with effective online learning implementation in Tanzanian Higher Learning
Institutions (THLIs). Fourteen (14) THLIs were surveyed, using face-to-face interviews
in focus groups. The groups included Lecturers, Heads of ICT Departments, ICT
Technical Personnel as well as Administrative Staff. Results indicate that mostly,
problems with effective online implementation in
THLIs are centred on a severe scarcity of online resources and tools and that the main
challenges lie in going beyond the process of integrating technology with their teaching
curricular, so that training of both teaching and supporting staffs also poses a big
challenge in the process. In addition, opportunities for e-learning are totally unexplored
because of the low pace of THLIs’ online learning practices. In this respect, THLIs are
required to devise and implement clear and welldefined e-learning strategies before they
can move a step further. Key Words: ICT, e-learning, online learning, THLIs
CHARACTERIZATION OF ON-ROAD PETROL VEHICLE EMISSIONS
PATTERNS IN DAR ES SALAAM CITY (TANZANIA)
Geoffrey R. John
Energy Engineering Department, University of Dar es Salaam,
P.O.Box 35131 Dar es Salaam, Tanzania, Tel +255 744319945, Fax +255 (22)2410114
E-mail grkjohn@uccmail.co.tz
ABSTRACT
Motor vehicle emissions have been identified to be the major source of air pollution in
most urban cities. It has serious impact on urban air quality and public health. The
Governments of many countries need to adopt stringent vehicle emissions regulations to
protect the air quality, the undertaking of which can only be implemented once the
problem at hand is known. In the present study, the characteristics of on road vehicle
emissions from the selected local areas at the
city of Dar es Salaam in a developing country for in-use petrol vehicles for urban driving
conditions ranging from idling, 10km/h to 70km/h have been studied under the in situ
measurements. This is equivalent to the European On Board Diagnostic, EOBD, testing
systems. The measured vehicle exhaust emissions concentrations from the testing system
have been further calculated into the vehicle emission factors for different driving
conditions. The results indicate that on-road vehicle driving conditions and road
characteristics have a direct effect on the characterization of vehicle emission factors. A
modest correlation of the calculated average emission factors has been realized when
compared with results from other countries and world bodies on the authority. Key
words: Motor vehicle emissions; Gaseous emission factors, European on board
Diagnostic System

IMPACT OF INSTITUTIONAL FRAMEWORK ON
WETLAND MANAGEMENT IN TANZANIA
Shadrack Mwakalila
Department of Geography, University of Dar es Salaam
P. O. Box 35049, Dar es Salaam, TANZANIA
Tel: +255-713-271299; Fax: +255-22-2410393
E-mail: smwakalila@yahoo.com

ABSTRACT
Wetland loss continues today despite the existence of institutions with a specific mandate
to manage wetlands in Tanzania. In reviewing this apparent contradiction, this paper goes
in depth to explore the existing sectors associated with the development and management
of wetlands in the Country. Specifically it focuses on institutional framework at Village
level, Ward level, District level and national level. Among the key sectors consulted
includes; agriculture and
livestock, wildlife, forestry, fisheries, water resources, lands, minerals and energy. The
interest while visiting them was aiming at exploring the existing opportunity with regard
to the values of the wetlands and their respective policies. The findings of this study show
that, wetland loss continues today despite the existence of institutions with a specific
mandate to manage wetlands. The principle factors contributing to this institutional
inefficient are: sectoral organization
of wetland management; limited availability of management techniques for protected
wetland; shortage of qualified staff; inadequate legislation; and limited resources. This
paper therefore, recommends the mitigating measures in order to sustain wetland
resources use and management.
Key words: institutional framework, wetland management, stakeholders

INVESTIGATION ON DISTRIBUTION OF CAST PROPERTIES ON
ALUMINUM PLATES POURED BY SIDE GATING TECHNIQUE
J. Runyoro
P.O. Box 35131, Dar es salaam, Tanzania, East Africa
Email: owekisha@uccmail.co.tz
ABSTRACT
Casting technologies which improve casting yield and internal soundness of thin wall cast
components are of particular interest to industry especially for critical applications. The
main aim of foundries is to achieve castings free from defects at low cost. It has been
thought that pouring casting by side ingate technique improve directional solidification as
the metal stays hot for long time in the feeder cum ingate. Experiments were carried out
using a side gating technique to cast
a number of 300 mm x 300 mm LMO and LM 25 plates in furan and pepset sand moulds.
The thickness used was 5 and 10 mm for furan and pepset sand moulds respectively. The
plates were divided into sections and tests carried out. The variation in plate thickness
with temperature as well with bending stress and crack length was observed and recorded
in plates made out of LMO materials. Tensile tests were carried out on LM 25 alloy and
the relationship between pouring
temperature, pouring rate, plate thickness, and pouring time with specimen location with
respect to ingate in the casting was established. Plates poured at low rates but high
temperature or vice versa give consistent thickness values. High pouring temperature and
pouring rates in sand moulds give uneven thickness along the plate casting. Thin castings
poured by side gating technique showed a tendency of cracking in a three point bending
test, exhibited high strength
scatter and severe porosity in the casting. Majority of the cracks were less than 3 mm in
length.
Key words: Side ingate technique, plate casting, porosity, strength, oxide films

PERFORMANCE OF AEROBIC BIOREACTORS DURING TREATMENT
OF TANNING INDUSTRY WASTEWATER
S.V. Manyele
Department of Chemical & Process Engineering, University of Dar es Salaam,
P.O. Box 35131, Dar es Salaam, Tanzania,
E-mail: smanyele@cpe.udsm.ac.tz

ABSTRACT
The performance of aerobic bioreactors loaded with novel biomass support (the KMT®
support particles) during the treatment of tanning industry wastewater is presented in this
paper. The wastewater samples were collected from TANWAT Company in Njombe,
which extracts tannins from barks of the wattle tree. The wastewater generated from
TANWAT is very acidic with high loading of organic compounds, which are very
complex and difficult to biodegrade using conventional methods. The paper introduces a
new technology for treatment of heavily loaded industrial wastewater, like tannins, that is
the Three-Phase Fluidized Bed Bioreactor (TPFBB) which utilizes the KMT® support
particles. Bench scale bioreactors (BSBs) were used to establish the suitable inoculum for
use in the TPFBB. To establish the effect of the KMT® support particles, the BSBs were
operated with and without the biomass support particles (BSPs). The BSBs were also
inoculated with different types of inoculum (waste stabilization ponds (WSP) and rumen
fluid (RF) inoculums) to establish the suitable source of microorganisms. Control
samples were also implemented accordingly. The results show that the WSP was a
suitable inoculum for which high chemical oxygen demand (COD) removal efficiency
and tannins concentration reduction efficiency (TCRE) were observed. Tests conducted
in the TPFBB with initial COD of about 13,200 ppm shows that the reactor is capable of
biodegrading the tannins (at 85% efficiency) after aeration times of up to 7 days in
recirculation mode. The final COD values of 1,000 ppm were reached in most cases. For
final discharge, however, such a final COD necessitates the use of sub-surface flow
constructed wetland (SSFCW) coupled to the TPFBB for final smoothing of the effluent.
The TPFBB is recommended for treatment of tannin wastewater to minimize chemical
pollution in the receiving water bodies.
Key words: Tannins; biomass support particles; wastewater treatment; aerobic
bioreactors; aeration.

DETERMINATION OF WIND LOADS CAUSING FLUTTER EFFECTS
Ladislaus Lwambuka1
Email: llwambuka@yahoo.de

ABSTRACT
A new method on the determination of wind forces by experimental means in a wind
tunnel is discussed. The method reported herein is based on the identification
methodology of model parameters under time response (i.e. time domain identification).
As a test model, a thin plate of cypress wood, elastically suspended in three degrees of
freedom to represent the idealized form of a classical airfoil, for which theoretical wind
load parameters exist, has been employed. Wind
load parameters, experimentally obtained on the test model under the new method, are
compared with the theoretical values of classical airfoils. Advantages of the new method
against the conventional methods are discussed.

GEOPHYSICAL EXPLORATION FOR GROUNDWATER RESOURCES
POTENTIAL OVER BASEMENT FORMATIONS AT KWANDOLWA AND
MWISHO WA SHAMBA VILLAGES, KOROGWE DISTRICT, TANZANIA
C. F. Mhilu
Department of Energy Engineering, University of Dar es Salaam,
P.O. Box 35131, Dar es Salaam, Tanzania: e-mail: cfmhilu@hotmail.com
ABSTRACT
In this paper results of geophysical exploration studies to identify potential areas with
groundwater resources at Kwamndolwa and Mwisho wa Shamba Villages in Korogwe
District have been presented. The resistivity curves of eight sites at the two study areas
were obtained using field data measurements made based on the application of a vertical
electrical sounding (VES) method. The resisivity values obtained for sites VES-K3 and
VES-M2 were found to be 10.9 and 24.0 ohm-m respectively. The interpretation of the
resisivity values made for the two sites gave also an indication of the presence of
sedimentary rocks composed of sandstone materials at the basements, known to
constitute a good water bearing potential. These results are to be used as a guideline for
borehole siting, providing information on the depth to the
groundwater relevant to the development of effective water supply schemes at the study
areas. Verification of the exact quality of water will be obtained during drilling tests.
Keywords: Geophysical, Groundwater, Exploration, Interpretation, Methods

SAMPLING PROCEDURE FOR PAVEMENT CONDITION EVALUATION
OF LOCAL COLLECTORS AND ACCESS ROADS
David A. Mfinanga
Email: mfinanga@ce.udsm.ac.tz

ABSTRACT
Road surface condition evaluation involves the collection of a lot of data on different
types of distresses. The exercise consumes a lot of resources if the whole road section
length is surveyed and may be prone to errors as a result of surveyors’ fatigue. It is
therefore important to develop a representative sample to be used when evaluating road
condition manually. This study aimed at determining an adequate sample size for
condition evaluation of local collector and access
roads in urban areas in Tanzania. Two such roads namely Lufungira and Kilimahewa
roads respectively were selected for the study. It is recommended that a section sample of
20 m long from the beginning of a 100 m section be used in evaluating the pavement
surface condition of such roads. This will result in a reasonably accurate representation of
the condition of the whole section with huge savings in resources.
Keywords: Pavement condition evaluation, road sampling, pavement management,
pavement
maintenance/rehabilitation.

GEOMETRIC PROGRAMMING AS A GENERAL METHOD FOR PHASE
AND REACTION EQUILIBRIUM CALCULATIONS
Godwill D. Mrema
Department of Chemical and Process Engineering, University of Dare s Salaam
P.O. Box 35131, Dar es Salaam: mremag@udsm.ac.tz

ABSTRACT
Geometric programming has been used to calculate a large number of different ideal and
non-ideal equilibria, including, for the first time, combined non-ideal reaction and phase
equilibria. For non-ideal systems the primal program is solved a number of times with the
non-ideal terms fixed each time. After each primal solution, the non-ideal terms are
updated using the corresponding dual solution. This iteration generally converges. We
have included one counter-example, where
the failure is caused by the equation of state, which cannot give correct roots.
Keywords: Multi-phase equilibrium calculations; reaction equilibrium calculations;
geometric programming;
UNIFAC.

AN INTERVENTION FRAMEWORK BASED ON A COMPLEMENTARY
THEORY OF ORGANIZATIONAL DECLINE
George S. Mwaluko and Beatus A.T. Kund11
Department of Engineering Management and Entrepreneurship
University of Dar es Salaam
Email: gmwaluko@yahoo.com and kundi@udsm.ac.tz

ABSTRACT
This paper has developed an intervention framework based a complementary theory of
organization decline. Any management intervention effort is normally based on a certain
theory of organizational decline i.e. a theory that explains the causes for failure of
organizations. Four major theories of organisational decline were identified in the
literature, reviewed and integrated into one, presumably more superior, theory of
organisational decline. They included the natural
selection theory, the resource-based theory, the theory of misperception of feedback and
the contingency theory. The new theory was then used to guide the design of an
intervention framework. The framework was then used to produce and evaluate an
intervention in one manufacturing firm based in South Africa. The results support the
efficacy of the integrated theory and it is concluded that in order to ensure that
intervention efforts produce successful results, the
underlying framework of such efforts must be based on a relatively adequate theory of
organizational decline. It is also concluded that the complementary theory of
organizational is relatively more adequate compared to the four theories of
decline that are discussed in the paper.
Keywords: Management Interventions, Organizational decline and theory of
organizational decline

DAR ES SALAAM WATER SUPPLY PROBLEMS AND
POSSIBLE SOLUTIONS: Reflections
D. A. MASHAURI, mashauri@udsm.ac.tz
Water Resources Engineering Department
P.O.BOX 35131 DAR-ES-SALAAM

ABSTRACT
Dar es Salaam is the largest and most rapidly growing city, (with a growth rate of about
7% per annum) in Tanzania with an estimated population of over 2.8 million people. Like
all Regional Headquarters Water Supplies and Water Supply to Dar es Salaam City
residents is inadequate. Since 1982 water demand has exceeded total water production
capacity of the three plants namely Mtoni; Upper Ruvu and Lower Ruvu. In 1989 the
estimated water demand was
about 289,760 m3/day while total estimated water production was about 239,560 m3/day.
giving a deficit of 50,000 m3/day. Estimated production from the three plants is Mtoni
4,520 m3/day, Upper Ruvu 54,340 m3/day and lower 180,800 m3/day (Ministry of
Water, 1989). The location of the plants and the main pipeline network is as shown of
Figure 1 below. The problems of water supply can be those of quantity and invariably
those of quality. There is not a doubt that the
supplied quantity has been exceeded by the demand. In future this demand will be
beyond what the present sources can ever supply. There is therefore a need to develop
other augmentation systems through short term and long term plans. Under short term
solutions shallow wells, boreholes and rain water harvesting should be considered. Long
term solutions
should include development of the Kizinga and Mzinga reservoirs which would release
up to 1,000 m3/day. The development of the proposed Kidunda reservoir upstream of the
present Ruvu intakes will enhance the supply up to 2.2 million m3/day which surpasses
the year 2020 demand of about 1,000,000 m3/day. The quality of water from deep
boreholes is usually of acceptable levels in terms of physical, chemical and
bacteriological parameters. In some cases the quality does not meet the Tanzania
Standard, therefore calls for treatment. Saline water intrusion is another problem to be
tackled especially for ground water exploitation along the coastal belt. Shallow wells
which are invariably from shallow aquifers are prone to pollution. It is therefore to be
expected that their waters will need treatment. Often shallow wells do not produce water
which meets the international standards in terms of chloride, nitrate
and pathogenic organisms quality. This paper is an attempt to highlight the water
problems facing the Dar es Salaam residents and propose possible solutions to the same.
The paper points out the possible short and long term solutions.
Keywords: Unaccounted for Water, Water Resources Management, Kidunda Reservoir
Development, Ground Water Development and Quality, Nitrate Problems in
Groundwater Sources.

Vol. 1(3) 2007

PROGRAM FOR THE ANALYSIS OF PLANE TRUSSES
John K. Makunza
Lecturer in Structural Engineering
University of Dar es Salaam, Tanzania

ABSTRACT
The ‘TRAP - TRuss Analysis Program’ can assist engineers in the analysis of plane
truss-type structures, as well as prove an excellent basis for understanding the “finite –
element” method. The Program is completely menu-driven, with all nodes, elements, and
load data entered through an input file. TRAP includes plotting for displaying the truss
geometry in its original shape showing all nodes and support points. In the analysis
process, firstly the structure data; e.g number of nodes, elements, materials and supports
are to be defined. Secondly, element properties and support constraints have to be
specified. Finally, nodal global loads are then defined. The program output include;
displacements for each node, axial forces, length of each element and reactions at the
supports. The program aims at reducing the time of analysis and increase the accuracy of
calculations as well as storage of the analysed data. The program caters for manual
methods of truss analysis such as method of sections or joint method. It has been found
that the program is efficient and has no limitations on the number of nodes and elements.
The program is suitable for use by design engineers in analysing Plane – Trusses of any
size

FOAMING CHARACTERISTICS OF THE FOOD-INDUSTRY
BIOLOGICAL WASTEWATER TREATMENT PLANT
Manyele S.V.
Department of Chemical & Process Engineering, College of Engineering and
Technology
University of Dar es Salaam, P.O. Box 35131, Dar es Salaam, Tanzania
smanyele@cpe.udsm.ac.tz

ABSTRACT
Intensive foaming observed during aeration of the aerobic food industry wastewater
treatment plant is presented. This study was conducted to establish the foaming
characteristics using a pilot three-phase fluidized bed bioreactor (TPFBB). A fluidization
column (0.2 m i.d. and 6 m high) was used. The TPFBB was loaded with variable masses
of novel biomass support particles (BSP). Wastewater samples collected from a plant
processing both vegetable oil (VOPWW) and soap
(SPWW) were immediately introduced in the TPFBB for aeration. The characteristics
studied include: variation of foam volume with time, foam multiplicity, foaming and
foam collapse rates. The SPWW produced excessive foam volumes at a higher rate and
higher foam multiplicity compared to VOPWW. Dilution, increasing aeration rate or BSP
loading led to higher foaming rate, which decreased with time. Spraying wastewater at
the top of the liquid surface minimized foaming rate.
Keywords: Food processing aspects; Vegetable protein derivatives; oils; rate of foaming;
foam collapse rate; biomass
support loading.

OPTIMAL UTILIZATION OF TIMBER POLES AS STRUCTURAL
MEMBERS OF FORMWORK
Ladislaus Lwambuka1
Email: llwambuka@yahoo.de
ABSTRACT
Timber poles of the type “Mirunda” are commonly used in East Africa as formwork
support structures for casting of reinforced concrete slabs, beams and canopies. It is also
widely known that the “Mirunda” poles as structural members of formwork are massively
used without any
structural consideration and guidance. This common practice has resulted into wastage of
natural resources and escalated construction costs. This study has attempted to establish
the load bearing capacity of randomly selected “Mirunda” poles through laboratory
testing. Using an existing construction site as a case study, the results have been used to
establish the actual
number of timber poles required to support freshly cast reinforced concrete slabs, beams
and canopies. The loading has been assumed for normal accessibility as per specifications
in BS 6399: Part1 (1984).with a dynamic factor arising from the impact of dropping the
concrete
onto the formwork as well as the dynamic effect of the concrete vibrating machine. A
comparison has been made between the actual requirement and the quantity of timber
poles counted on site. On basis of the study findings appropriate recommendations have
been provided on how “Mirunda” poles can be optimally utilized as structural members
of formwork.

PRELIMINARY ESTIMATES OF BUILDING COST AND
THE LOWEST EVALUATED TENDER
Harriet K Eliufoo
School of Construction Economics
Ardhi University, P.O.Box 35176
DAR ES SALAAM: [heliufoo@yahoo.com]

ABSTRACT
The paper has investigated and established to what extent are preliminary estimates of
building costs close to the lowest evaluated tender and how geographical proximity
influences the variance between preliminary estimate and the lowest evaluated tender. A
multiple case study constituting 43 building projects in Tanzania were statistically
analysed covering a period from
1995- 1999. Findings reveal a significant variance exists between the quantity surveyor’s
preliminary estimate figure and the lowest evaluated tender; and that the variance
between the quantity surveyor’s figure and the bidder is small when the proposed
building project is geographically closer to the quantity surveyor’s base. Analysis of
variance (one -
way) has shown geographical distance has a statistical significance on the variance
between the preliminary estimates and the lowest evaluated tender. The study has
established that the object of preliminary estimates in building costs, that of making the
client aware of his
financial obligations at early stages of a building project are not met fully.
Keywords: Preliminary estimates, prices, building projects, Tanzania, tender bid,
quantity surveyor

NYUMBA YA MUNGU RESERVOIR SYSTEM SIMULATION
BY USING HEC-RESSIM MODEL
1Deogratias M.M. Mulungu, 2Rejea Ng’ondya and 3Felix W. Mtalo
University of Dar es Salaam,
College of Engineering and Technology, Department of Water Resources Engineering
P.O Box 35131 Dar es Salaam
1deo@wrep.udsm.ac.tz; deorgm@yahoo.co.uk , 2mwandungu@yahoo.com and
3mtalo@wrep.udsm.ac.tz
ABSTRACT
This research paper focused on estimating effective water and optimization of the NyM
reservoir for storage conservation and hydropower generation. Several models were used
in the study: the Rainfall-Runoff model, GFFS was used to fill in missing data, and the
HEC-ResSim Model and the NWBM for reservoir system simulation and water balance
respectively. The effective inflows to the NyM reservoir were determined using HEC-
ResSim model and the NWBM used to check the total water loss in the system. For the
reservoir system simulation, the HEC-ResSim model was used to estimate water loss
through irrigation abstractions in Kikuletwa and Ruvu reaches before water enters the
NyM reservoir. The loss was estimated to be 27% of the total inflows at 1DD1 and 1DC1
gauging stations upstream the reservoir. Reservoir evaporation was estimated using pan
evaporation data collected from NyM meteorological station.
The effective inflows are important data to the reservoir system simulations for power
production. The mean value of effective water reaching the NyM compared well with the
previous study measurement of the dry season value, which was done before the dam
construction. The HEC-ResSim simulated releases were used to determine the power
production at NyM hydropower plant. Considering water abstractions, the first simulated
alternative favored storage conservation in the reservoir. The power achieved in this
alternative was 7% above the TANESCO production (41.6 GWh/yr). The second
simulated alternative was to maximize power production at NyM hydropower plant. This
alternative yielded 13% above TANESCO production. Despite the high energy attainable
in maximization option, the reservoir water levels trend was seen to draw down
drastically. The study also investigated the extent of the impact brought about by the
abstracted
water. If irrigation abstractions were restricted from the two reaches then power
production would increase by 11.5 GWh. This increment is about 24% above the power
produced when abstraction is allowed in Ruvu and Kikuletwa River reaches.
Keywords: firm power, HEC-ResSim model, hydroelectric power, Nyumba ya Mungu
Reservoir, reservoir simulation,
spillage, water abstractions

SOCIO-ECONOMIC IMPACTS OF WATER SCARCITY IN DAR ES SALAAM,
TANZANIA
Shadrack Mwakalila
Department of Geography
University of Dar es Salaam
P. O. Box 35049, Dar es Salaam, Tanzania
Email: smwakalila@yahoo.com

ABSTRACT
Drought and the resulting low water levels in rivers exacerbate water scarcity conditions
in Dar es Salaam city. The result is frequent water rationing in areas served with piped
water, sometimes for days or weeks, and low water pressure, which leads residents to
resort to other less safe and sometimes more expensive water sources. The frequent and
current response to the inadequate piped water supply in Dar es Salaam has been the use
of groundwater resources. There are
both public and private bore-holes and wells drilling companies in Dar es Salaam.. This
paper therefore, presents some socio-economic impacts of water scarcity in Dar es
Salaam city. The methodology employed in field data and information collection includes
interviews, questionnaire, focus group discussions and participatory observation. This is
data triangulation, an essential technique for improving the reliability of data and
information. The study reveals that the
participation of local community (including water vendors and private business
entrepreneurs) in water delivery systems through drilling bore-holes and shallow wells
has improved water supplies in the study areas. However, the study has revealed some
problems related to water scarcity in Dar es Salaam. These include high prices for water,
poor sanitation and hygiene, unsafe and unclean water and inconvenient payment
systems. Poor sanitation is related to stagnant water
around the bore-holes and shallow wells. It is noted that unsafe water is mainly a problem
for those obtaining water from water vendors and/or hire young men to collect water for
household uses. However, the study concludes that individual’s participation in water
delivery systems in Dar es Salaam City has positively improved the life standards of the
local people, particularly the poor.
Keywords: Dar es Salaam, Shallow wells, Water scarcity, Water vendors.

ADAPTIVE IIR FILTERS FOR SINGLE INTERFERENCE SUPPRESSION IN
A BPSK DS CDMA SYSTEM IN RAYLEIGH FADING CHANNEL
Aloys N. Mvuma
Telecommunications Engineering Department
University of Dar es Salaam
P.O. Box 35131 Dar es Salaam, TANZANIA
mvuma@udsm.ac.tz

ABSTRACT
In this paper, effect of a single narrow-band interference (NBI) on bit error rate (BER)
performance for a binary phase shift keying (BPSK) synchronous direct-sequence code-
division multiple access (DS CDMA) communication system operating in a frequency
nonselective Rayleigh fading channel is analyzed. Second-order adaptive infinite impulse
response (IIR) notch filters with plain gradient algorithm (GA) for suppression of NBI in
the DS CDMA system are
proposed. A general closed-form BER expression for the DS CDMA system with NBI
suppression second order adaptive IIR notch filters is derived based on the standard
Gaussian approximation (SGA) method. BER expressions are then derived for the allpass
filter-based adaptive IIR notch filter and adaptive IIR notch filter with constrained poles
and zeros, the two structures that are commonly found in literature. It is observed that
both adaptive IIR notch filter structures exhibit comparable BER performance. Extensive
computer simulation results are presented to verify the
accuracy and limitations of the analysis.
Keywords: Direct-sequence code-division multiple access, narrow-band interference,
adaptive notch filters, bit error

SOFTWARE ENGINEERING: A FUNDAMENTAL APPROACH TO
AUTOMATE AND INTERFACE MEDICAL ELECTRONIC SYSTEMS
WITH COMPUTERS IN HEALTHCARE SYSTEMS
Hashim M. Twaakyondo and Joseph E. Mbowe
Department of Computer Science, University of Dar es Salaam
P.O. Box 35062 Dar es Salaam
e-mail: htwaaky@udsm.ac.tz, hmtwaaky@yahoo.com

ABSTRACT
The cost for application software and propriatry standards (i.e. data structure and
formats) required for storing clinical datasets from electronic device cause the use of
time-consuming paper-based documentation and/or the transfer of electronic lab records
manually to the PC database systems in Mother-Offspring Malaria Study (MOMS)
Laboratory Unit located in Morogoro Regional Hospital, Tanzania. We have explored
the ability to extract laboratory results from Haematology analyzer machine for easy
management, access and storage. The methodology and tools used during the study
includes; site survey and hands-on practice for requirement engineering, visual basic 6.0
for interface design and Microsoft Access for relational database design. The study has
developed a model “COmpose-TRAansmit-COnvent-COmpose” convention (acronym
COTRACOCO) to implements an open serial port interface that required only a driver
class to execute the labs outputs for storage in database with at run-time with less
programming knowledge. The study demonstrated that the COTRACOCO convention
presented is general and may promote a new paradigm for establishing the robust serial
port communication systems for any digital device
Key words : COTRACOCO , Serial Port, LIMS , MOMS, PC Database systems and ABX
Micros 60 OS/OT.

ROBUST OUTPUT FEEDBACK OF MINIMUM PHASE
NON LINEAR SYSTEMS
Emrod Elisante
Department of Chemical & Process Engineering, University of Dar es Salaam
P. O. Box 35131 Dar es Salaam, Tanzania
elisante@cpe.udsm.ac.tz, Tel +255-22-2410368
ABSTRACT
A robust output feedback controller is synthesized for minimum phase multivariable
nonlinear systems based on the differential geometry approach. Using the internal model
control structure within the input-output (I/O) linearization framework, the controller is
combined with a closed-loop observer to estimate transformed states in the outer-loop. It
is shown that the controller-observer combination achieves robust tracking and
estimation using simple tuning parameters. The effectiveness of the proposed system is
illustrated by a simulation example for control of concentration
in a chemical reactor.
Key words: Nonlinear control, input-output linearization, output feedback, robust
control, chemical processes, multivariable systems.

A GEOTECHNICAL STUDY ON THE CHARACTERISTICS OF
SWELL-SHRINK SOILS IN KIBAHA, TANZANIA
Charles Lucian1, Staffan Hintze2, Joseph J. Msambichaka3
1University College of Lands and architectural Studies (UCLAS), P.O. Box 35176, Dar
es Salaam, Tanzania
2Division of Soil and Rock Mechanics, Department of Civil and Architectural
Engineering,
Royal Institute of Technology (KTH), Stockholm, Sweden.
3College of Engineering and Technology, University of Dar es Salaam, P.O. Box 35131,
Dar es Salaam, Tanzania

ABSTRACT
The properties of Swell-shrink of the soils in Kibaha were studied. Geotechnical and
mineralogical tests were carried out on disturbed and undisturbed samples recovered
from trial pits at different locations. Using empirical relationships, the swelling potential
of the soil was established in correlation with the soil plasticity limits and grain size
analysis (clay contents). The average values for the plastic, liquid and linear shrinkage
limits for soils were 22.2%, 60.7% and 14.5%
respectively. The plasticity Index (PI) which is the difference between liquid limits and
plastic limits ranges from 27% to 47.4% with an average of 38.5%. The natural water
content is very small ranging from 7% to 11% with an average of 9.6% which is smaller
than the corresponding shrinkage limit. Furthermore, the samples were tested for
percentage of volume change in free swell tests and swelling pressure in onedimensional
swell tests. The free swell and upward pressure were in the excess of 100% to 150% and
50 kPa respectively. In addition, the coefficient of linear extensibility ranged from 0.09 to
0.14 signifying high to very high swellshrink
potential. Finally, the main clay mineral present in the sample was determined by running
the X-ray diffraction (XRD) test. The xray diffraction scan indicated the presence of high
proportion of clay minerals (smectite) in the soils.
Key Words: Swell-shrink soils, soil index properties, potential swell, montmorillonite
(smectite)

IMPACTS OF LAKE VICTORIA LEVEL FLUCTUATIONS TO
LIVELIHOODS MISSUNGWI DISTRICT CASE STUDY
Kimaro, T.A. and Fidelis, R.
Water Resources Engineering Department, University of Dar es Salaam,
P.O. Box., 35131, Dar es Salaam, tel./fax +255-22-2410029, Tanzania.
e-mail: kimaro@wrep.udsm.ac.tz and cothilds_fidelis@yahoo.com
ABSTRACT
Lake Victoria experienced drastic levels changes in 2005 causing great inconveniences to
lakeside communities. This study investigated effects of these changes on livelihoods
through questionnaire surveys, focused group discussions, interviews and analysis of fish
catches, diseases, crops, and lake levels data. Results indicate recession of levels had
various socio-economic impacts. The changes caused severe water shortage due to drying
up of shallow wells and a remarkable increase in prevalence of schistosomiasis because
of increased utilization of lake water. There was no evidence for impact of level changes
on malaria and diarrhea. Decline of water levels caused decline in fish catches due to
retreat of water from breeding sites. However receding waters created a new land for
cultivation which helped to
boost Maize and sweet potatoes production. The results emphasize on ensuring stability
of lake levels to avoid negative impacts on livelihoods and to maintain ecological
integrity of the lake.
Key words: Lake Victorial, socio-economic impacts, fisheries, water related dieseas,
water supply

ASSESSMENT OF STRENGTH COMPLIANCE WITH STANDARDS
FOR TANZANIA EUCALYPTUS WOOD POLES TREATED WITH
COPPER-CHROMIUM-ARSENIC COMPOUNDS
Alex Lyatonga Mrema
Senior Lecturer, Department of Structural Engineering, College of Engineering and
Technology,
University of Dar es Salaam, Tanzania. Email: mrema@ce.udsm.ac.tz,

ABSTRACT
Samples of copper-chromium arsenic compounds (CCA) treated Eucalyptus poles for
power transmission were sampled from a lot following Military Standard MIL-STD
105D, Single sampling, Tightened Inspection, Acceptable Quality Level (AQL) of 4 as
provided for in the South African Standard SABS 754:1994 from lots containing 151-500
poles. Samples
were randomly selected from a lot. Maximum fiber stresses were evaluated taking into
account the actual taper in each pole. The cantilever loading test was performed on the
samples following SABS 754:1994. It was found out that the average taper for the poles
was smaller than that assumed in the standard due to the different pole growth
characteristics and environment in Tanzania and that the average modulus of elasticity
obtained for the poles was lower
than the average assumed in SABS 754:1994. The poles also showed excessive
deflections at working loads. It is recommended to the Tanzania Bureau of Standards that
although SABS 754:1994 is meant to be used for eucalyptus poles grown in Southern
Africa south of the Sahara that are treated with creosote or CCA there is a need to review
it to take into account the actual characteristics of the poles grown in Tanzania where
they are normally grown in highland
areas with higher rainfall and colder climates.
Keywords: eucalyptus poles, quality verification, cantilever load test

MODELLING OF AGRICULTURAL NON-POINT SOURCES POLLUTANTS IN
UPPER PANGANI RIVER BASIN (UPRB), TANZANIA
Mwanuzi Fredrick,
University of Dar es salaam Box 35131
Dar es Salaam, Tanzania fmwanuzi@yahoo.com Box 35131

ABSTRACT
The Upper Pangani River and its watershed are increasingly being impacted by
environmental problems which include non point source pollutants that are threatening
the watershed resources. Increased human activities due to population increase, and
hence agricultural activities, livestock development, the use of agrochemicals and other
land development
in the basin, have tended to lead to a serious pollution of the river water which also
affects not only the aquatic life but also human health. With intensive and extensive
modern agriculture in which artificial fertilizers are in frequent use, there is a high
probability to find chemicals easily flowing into water, thus polluting it. The introduction
of agricultural chemicals in
rivers may be detrimental. Nitrogen and Phosphorus which are present in agricultural
chemicals are essential plant nutrients, which when introduced into surface waters may
cause some health problems such as blue-baby syndrome and stomach cancer. To carry
out this study we divided the Upper Pangani River basin into two sub-basins; Kikuletwa
and Ruvu. The study
concentrated on Ruvu sub-basin to study and model the pollution transported to the
rivers. QUAL2E model was chosen and applied to assess the pollution status of the river
network. The model simulated stream flow, dissolved oxygen, phosphorus and nitrogen
compounds. From model results, the amount of non-point source load reaching Ruvu
river was found to be 7857.81tons/yr for nitrogen and 12057.39 tons/yr for phosphorus.
The results of the QUAL2E model suggest that there is pollution at upstream rivers as a
result of application of fertilizers to the irrigation schemes which are the main sources of
non point source pollution.
Key Words: Non-point source, Pangani river, Irrigation, Nutrients, QULA2E model

USE OF SIMPLIFIED MATHEMATICAL FORMULATIONS IN MULTI PHASE
THERMAL PUMP (MPTP) FOR THEORETICAL PREDICTION OF WORKING
CONDITIONS
Francis A. Chami fachami@uccmail.co.tz
Department of Energy Engineering, College of Engineering and Technology
University of Dar es Salaam, P.O. Box 35131, Dar es Salaam, Tanzania

ABSTRACT
In this work mathematical expressions have been formed and solved to get predictions of
working parameters of multi phase thermal pump (MPTP). MPTP is a simple pump
which uses steam to pump water. The results have been compared with data found
experimentally. Experimental and theoretical values for a range of pressures versus
velocity differed by approximately 8.7% up 12% Through dimensional analysis
dimensionless parameters were found Re, Eu, Fo and h/dpmp .
These helped to further elucidate the pump’s pumping phenomenon. It was
experimentally shown that the Reynolds number found theoretically gave limit of flow
operating regime of the pump that it is in the transition regime. Above this the pump
failed to operate. The Euler dimensionless number gave the dependency of interface
velocity on pressure relation, when pressure was raised the velocity increased. The
relation between the two parameters was found to be
approximately quadratic. The Fourier dimensionless number gave the influence of heat
transfer properties of the material of the pump to the operating characteristics. It was
experimentally found that the influence of the overall heat transfer coefficient and heat
transfer were the main driving forces behind the operation of the pump. Average interface
velocities in the pump were found using pipe flow energy and mass conservation
equations. Conditions for operation (pumping and suction) of the pump have been
established based on the formed mathematical formulations.
Keywords: Steam water pump; pump characteristics; dimensionless parameters; steam

STUDY OF NUTRIENT POLLUTANTS AND THEIR IMPACTS ON
THE WATER QUALITY OF THE MINDU RESERVOIR AT MOROGORO
MUNICIPALITY
Consolatha J. Ngonyani1 and Hudson H. Nkotagu2
1 = Ngonyani Consolatha, J., University of Dar es Salaam CoET Chemical and Process
Engineering,
P.O. Box 35131 Dar Es salaam Tanzania (konsolatha@yahoo.com).
2 = Nkotagu, H. H., University of Dar Es Salaam, Faculty of Science, Geology
Department,
P. O. Box 35052, Dar Es Salaam, Tanzania (hudson@.udsm.ac.tz).

ABSTRACT
The physical-chemical parameters characterization of Mindu Reservoir, whose 50% of its
waters is being plagued by aquatic weeds, involved the analyses of water and sediment
samples that were collected during the dry season. As the nutrients levels of Mindu
waters were determined, phosphorous (TP - PO4 3-) levels were found to be high enough
for supporting eutrophication process. Likewise Nitrogen/Phosphorous ratios average of
8.51 4.32 suggested a Redfield
behavior of nutrients with nitrogen being a limiting one. The dominant clay minerals of
the Mindu surficial sediments were found to be kaolin and illite, where as the Cation
Exchange Capacity values were found to be high enough for the sorption of nutrients and
pollutants. Both river inflows, overlay-flows and sediments forms the mode of transport
of nutrient, with the later behaving as sinks of nutrients through out the year. The
evaporation, bio-geo-chemical and
Nitrogen fixation processes along with macrophyte productivity, support the hypotheses
that physical-bio-geo-chemical processes influences the spatial distribution of major ion
in the Mindu Reservoir. These findings classify Mindu as eutrophic, calcium magnesium
bicarbonate type. A detailed multidisciplinary study that involves more than one year
cycle was recommended, to capture inter seasonal variability, and for the modeling of the
sequestration of nutrients in
various trophic levels.
Key words: Mindu reservoir, eutrophication, Redfield ratio, macrophyte, downstream
evaporation hydro
biogeochemistry.

Vol.2(2) 2008

INVESTIGATION OF THE EFFECT OF PARTICLE SIZE ON
GROUNDNUT-OIL SOLVENT EXTRACTION
S.V. Manyele ∗ and I.F. Kahemela
Chemical and Process Engineering Department, University of Dar es Salaam,
P.O. Box 35131, Dar es Salaam, Tanzania

Abstract
An investigation of the effect of particle size on the performance of vegetable oil
recovery by solvent
extraction is reported. Experiments were conducted using soxhlet extractor, groundnuts
and n-hexane.
Samples were grouped into mean particle sizes of 0.25, 0.75, 1.3, 3.3, and 7.5 mm using
standard sieves. The effect of particle size was studied for extraction time intervals of 1,
2, 3, 4, 5 and 8 hours. The oil yield, oil recovered per kg solvent used, kg solvent lost per
unit time, and the rate of extraction (kg oil recovered per hour) decreased with increasing
particle size. Meanwhile, the percent of solvent recovered, the ratio of oil recovered to
the total volatile matter driven off and the kg solvent lost per kg oil recovered, increased
with increasing particle size. Based on the normalization of averaged extraction-
parameters, a mean particle size of 3.3 mm was observed to be the optimum size.
Keywords: Solvent extraction, oilseeds, groundnuts, oils, particle size, solvent loss,
extraction time.

THE MULTIVARIATE STATISTICAL ANALYSIS OF ABIOTIC
PARAMETERS OF THE LAKE TANGANYIKA SUB CATCHMENT
H. H. Nkotagu
Geology Department, University of Dar es Salaam, P.O. Box 35052, Dar es Salaam
*e-mail: hudson@udsm.ac.tz

Abstract
Results from multivariate statistical analysis of abiotic parameters conducted during the
dry season at 20 accessible sites on 8 rivers, 2 lakes and a dam covering the Lake
Tanganyika sub catchment are discussed. Standard methods were used to determine the
levels of abiotic parameters from water samples. Physical parameters including DO, EC,
Eh, turbidity, temperature, pH and secchi transparency were measured in situ while
chlorophyll a was determined in the laboratory. Nutrients such as NO3 -, SiO2, PO4 3-
and Fe2+ were determined along with HCO3 -. Factor analysis resulted in four factors
including increased primary productivity, redox conditions, dissolution, and reduction
processes. Processes including dissolution, diffusion, adsorption, absorption, nitrification,
denitrification, mixing and reduction along with the anthropogenic activities, increased
photosynthetic activity of algae and the geomorphology of the ecosystems contribute to
the variation of the abiotic parameters. It is recommended that quantification of river
flows, sediment load and nutrient budget at various sampling points be determined
seasonally for proper evaluation of the hydrologic and limnological functioning of the
ecosystem.
Keywords: Multivariate statistics, Malagarasi Wetland, Abiotic parameters

IMPROVING THE DESIGN OF LOW VOLUME SEALED ROADS IN
TANZANIA
David A. Mfinanga and Lusekelo A. Mwakyami
Department of Transportation and Geotechnical Engineering
University of Dar es Salaam, P.O. Box 35131, Dar es Salaam, Tanzania
Tel: 0713-329690 Fax: 2410078
E-mail: mfinanga@ce.udsm.ac.tz

Abstract
The main objective of the study was to identify appropriate road designs for Low Volume
Sealed Roads (LVSRs) with the aim of improving the design of such roads in Tanzania.
The study was conducted in Dar es Salaam and Morogoro regions in Tanzania where data
for LVSRs were collected from primary and secondary sources in the two regions. The
study found that by using an improved pavement design method specifically meant for
LVSRs results in cost savings for LVSRs of up to 51% compared with the conventional
method of pavement design in Tanzania. The study recommends that the pavement
design method for lightly trafficked sealed roads in southern Africa developed by
Transport Research Laboratory, which was found to be most cost-effective, be used to
design (or develop a procedure for design of) LVSRs in Tanzania and that the roads be
preferably sealed with Otta seal or Surface dressing. The study also recommends that
LVSRs in Tanzania be defined by a maximum traffic volume of 400 vpd.
Keywords: low-volume roads, low-volume sealed roads, pavement design

INTEGRATED REMOTE SENSING AND GIS TECHNIQUES FOR
GROUNDWATER EXPLORATION IN SEMI-ARID REGION:
A Case of Karamoja Region – Uganda
Lubang, B; Nobert, J. Mtalo, E.G
Department of Water Resources Engineering, College of Engineering and Technology
University of Dar es Salaam, Tanzania: E-mail: nobert@udsm.ac.tz

Abstract
Groundwater is a precious resource that covers wide geographical extent. Proper
evaluation is required in order to ensure prudent use of groundwater resources. The
current groundwater assessment in Karamoja region, as in many parts of the world, uses
Apparent Resistivity andVertical Electrical Sounding, which has limited coverage to
some localized usually predetermined areas. Comprehensive groundwater development
program needs a wide area coverage and large volume of multidisciplinary data. In the
present study, an integrated remote sensing and GIS based methodology is developed and
tested for the evaluation of groundwater resources of Karamoja Sub Region, Northeastern
Uganda. The components of the study are delineation of the groundwater potential zones
in the area and evaluation of the relationship between delineated groundwater potential
zones and aquifer characteristics.
The groundwater potential zones are determined by the relevant layers, which include
hydrogeomorphology, lineament density, slope, drainage density, overburden thickness
and aquifer depth, rainfall, geology, land use, and soil were integrated in Arc/Info grid
environment. Weighted index overlay method developed by Multi Criteria Analysis
(Analytical Hierarchy Process) was used to assign weights to the different map layers. All
the information layers were been integrated through GIS analysis, employing the use of
Natural Break (Jenks) method for classification. Alexandru groundwater potential zoning
using the Transmissivity values was used for the final classification of the potential zones
and correlation with ground-truth data. Over 70% correlation was achieved showing the
significance of GIS in groundwater mapping.
Key words: Groundwater exploration, interpretation Methods Remote sensing & GIS.

ANALYTICAL MODELING OF A LARGE LOCAL AREA NETWORK -
PART I: INTERNET TRAFFIC CHARACTERIZATION
Mathew L. Luhanga and Cuthbert E. B. M Amos
Department of Telecommunications Engineering, University of Dar es Salaam,
P.O Box 35131, Dar es Salaam, Tanzania
Emails: luhanga@udsm.ac.tz, amomsuya@udsm.ac.tz

Abstract
The goal of both IP network operators and the end users is to get the highest performance
from the system for a given cost. This makes Performance a key criterion in the design,
procurement, and use of computer and communication systems. In order to address
problems associated with performance degradation of operational communications
systems, over the last decade, traffic engineering techniques have emerged in an attempt
to optimize communication systems’ performance and ensure more efficient use of their
resources. One of these techniques is analytical modeling.
Analytic performance models are an excellent tool for quickly evaluating the
performance of operational or new systems. They are also well suited to comparing the
performance of several alternative designs. However, analytical models can only be
developed once detailed knowledge of characteristics of traffic carried by a network is
available. In Part I of this paper, traffic characterization of traffic carried by the largest
Local Area Network (LAN) in Tanzania, University of Dar es Salaam Network
(UDSMNET) is carried out. In Part II of this paper, an analytical model based on the
Discrete Time Markov Modulated Poisson Process is proposed and validated for
performance analysis of IP networks.
Key words: Traffic characterization, Traffic Engineering, Long Range Dependence

DESIGN AND DEVELOPMENT OF A PROTOTYPE FOR A WEB-BASED
INTERFACE FOR ONLINE MATERIAL FOR TANZANIAN YOUTH
Chumo, C.
Department of Anthropology
University of California, Davis
1 Shields Avenue
Davis, CA 94616 USA
Mjema, E.A.M.
Department of Engineering Management and
Entrepreneurship
University of Dar es Salaam
P.O. Box 35131, Dar es Salaam Tanzania

A prototype of a web-based interface for an online database was developed to be used by
youth organizations in Dar-es-Salaam. A participatory approach involving secondary
students in the identification of user interface requirements, in designing and testing the
prototype was used. A questionnaire was designed and manned in seven secondary
schools in Dar-es-Salaam to estimate the Internet usage. Interviews were conducted to
countercheck the questionnaire responses. The interview and the questionnaire helped to
come up with a set of user requirements for the web-based interface of an online
information search. From the specifications of the user requirements the author was able
to create a youth-friendly web based prototype that can be used by youth groups in Dar-
es-Salaam.

POTENTIAL USE OF WATERGUARD AS A DISINFECTANT
FOR DOMESTIC WATER USE
Yohana L1. and Mashauri, D. A2.
1PhD candidate, Water Resources Engineering Department, University of Dar es Salaam
ylawi@yahoo.com.
2Professor, Water Resources Engineering Department, University of Dar es Salaam,
mashauri@udsm.ac.tz

Abstract
Water Guard which consists of 0.75% sodium hypochlorite (chlorine-based water
disinfectant solution) has been identified as an alternative method for treatment of
domestic drinking water. The aim of this study was to investigate the effectiveness of
Water Guard in disinfecting drinking water from different sources drawn from Kinondoni
district, Dar es Salaam as well as to establish appropriate dosage that can be used during
the treatment. Results showed that, a dose of 4.0mL per 20 litrer of water guard is
sufficient for disinfection of urban water sources. The above prescribed doses provide
100% disinfection efficiency with residue chlorine of less than 0.3mg/l. Water with
turbidity values of 30-35 NTU, chlorine dosage of 8mL/20 litres is recommended and this
gives residue chlorine of 0.3 – 0.5 mg/L. From this study, it can be concluded that, Water
guard is effective against pathogen and that there is an increase of residue chlorine as the
dosage increases irrespective of from which source the water was drawn. Also the safety
of water is obtained even where the residual chlorine is less that 0.1mg/l. However, there
are health implications associated with the
use of Water Guard which need further research
Key words
Water Guard, pathogens, effectiveness, dosages, disinfection, residue chlorine.

IDENTIFICATION OF UNBALANCED FORCES AND FOUNDATION
PARAMETERS OF ROTATING MACHINES FROM VIBRATION
MEASUREMENTS
N.G. Nalitolela
Department of Mechanical and Industrial Engineering, University of Dar es Salaam,
P.O. Box 35131 Dar es Salaam. Email: noel@uccmail.co.tz

Abstract
A technique is described to use measured vibration data of a rotating machine and its
foundation to identify unbalanced forces, stiffness and damping parameters of the
mountings, and the parameters of the foundation. It is based on an idealisation treating
the rotor, the machine structure and the foundation as rigid masses supported by springs
and dampers. Operational vibration data of the machine and its foundation before and
after the rotating unbalanced forces are perturbed by adding unbalanced mass to the rotor
are used in the identification procedure. Once the parameters are identified, dynamic
forces transmitted to the foundation can be estimated. The technique is demonstrated
using simulated example for a machine with a two bearings rotor.
[Keywords: Identification, unbalanced forces, rotating machines, vibration, foundation]

AN EQUATION FOR ESTIMATING THE (R) USLE SLOPE
STEEPNESS FACTORS
Dr. Matthew K. Mulengera
Department of Agricultural Engineering and Land Planning,
Sokoine University of Agriculture, P. O. 3003, Chuo Kikuu, Morogoro, Tanzania
email: mulengera@yahoo.com

Abstract
Currently three equations are used for calculating slope steepness factor for the Revised
Universal Soil Loss Equation (RUSLE); one for slopes less than nine percent, the second
for slopes equal or greater than nine percent, and the third equation that has been
proposed for use in China for slopes equal or greater than 17 %. The three equations have
linear relationships between slope steepness factor, S and the sine of the slope angle, θ.
The three equations under predict the factor, S when used on slope steepness beyond the
data sets used to develop them. In addressing this problem several alternative forms of
equations (linear, power, and polynomial) were tested using field plot soil loss data
gathered by several researchers in different countries
for slopes ranging from three percent to 55 %. A single power function relating the sine
of the slope angle, θ to the slope steepness factor, S has been identified to be more
suitable and accurate for estimating the RUSLE slope steepness factor, S.
Keywords: Slope steepness factor; Soil loss prediction; Statistical regression

PEDESTRIANS’ CROSSING PROBLEMS AT THE MANZESE
FOOTBRIDGE AND PROPOSED MEASURES
1 Ali A. Shariff, 2 Saidi A. Tamba and 3 Azizi A. Mdimi
National Institute of Transport
P.O. Box 705, Dar es Salaam.
Email: 1alishariff50@yahoo.com , 2tamba1tz@yahoo.com and 3azmdimi@yahoo.co.uk

ABSTRACT
In its efforts to restore safety to pedestrians the Government of Tanzania constructed the
Manzese Footbridge along the Morogoro road. The project cost was TShs. 46,300
Million at the price in year 1990. The bridge design was carried out in accordance with
Road Bridge Design Manual published by Japan Road Association. Unfortunately, only
one pedestrian bridge has been built in Dar es Salaam since 1991. Footbridges and
underpasses have hundred percent potential of protecting the pedestrian’s safety when the
traffic stream being crossed is heavy. It is not known why this advantage is not fully
utilized by pedestrians in Dar es Salaam city. The paper tries to find out the reasons
behind this trend. A case study of the footbridge at Manzese and two neighbouring zebra
crossings one on either side of the bridge were used. Experimental data of the number of
pedestrians crossing at the bridge, Tip Top and Bakhresa zebra crossings at fifteen minute
intervals were collected for five working days starting from 1200 to 1515hours. The
average deviations of pedestrians crossing at Tip Top and Bakhresa from the bridge were
analysed by means of a paired t-statistic to uncover the usage inadequacy of the crossing
facilities. Manzese foot bridge quality was also analysed by the Five Point Likert Scale
using five quality attribute sentences. A random sample of 165 people was used in the
analysis. The t-statistic showed that the bridge crossing is not significant at 5% level but
significant at Tip Top and Bakhresa zebra crossings. This reveals that the pedestrians are
not using the bridge compared with the other two zebra crossings. The Likert method
showed that inadequate security, loss of muscle energy, no plaza, dizziness and no
facilities to attract crossing of all types of pedestrians are reasons hindering its use. It is
recommended that the above findings can be rectified by providing security lighting,
police patrol and modification of bridge structure.
Keywords: Dar es salaam, Morogoro Road, Manzese footbridge,. Under passes, zebra
crossing Fire Point Likert Scale, Paired t-test

CHARACTERISATION OF A MOBILE JAW CRUSHER FOR SMALL
SCALE MINING AND CONSTRUCTION INDUSTRY
A. J. M. Itika
Department of Mining and Mineral Processing, University of Dar es Salaam,
P. O. Box 35131, Dar es Salaam, Tanzania,
E-mail: aitika@udsm.ac.tz

ABSTRACT
A small jaw crusher with a crushing capacity of 1 ton per hour has been developed for
use in the small scale mining and construction industry. A 3.68 kW air cooled diesel
engine was installed to power the crusher. Laboratory and field test were conducted using
limestone as feed material at different operating parameters .The analysis of the product
from the crusher showed that at a constant jaw gap, coarser products were obtained when
the rotary speed was varied from 220 rpm to 300 rpm. With a jaw gap of 25 mm, a higher
cumulative undersize fraction was obtained at particle size 25 mm. In contrast, at a jaw
gap of 15 mm, higher cumulative undersize fraction was obtained at particle size 15 mm.
With a feed size 80% passing 60 mm, a finer product was obtained as compared to a feed
80% passing 120 mm. The throughput of the machine increased from 0.4 ton/hr to 0.7
ton/hr when the speed was increased from 220 rpm to 300 rpm. It was found that it is
possible to select a combination of operating parameters to achieve a particular goal of
operation.
(Key words: crushing, crusher, jaw crusher, size reduction, comminution, limestone
crushing, small scale
crushing machine)

THE EFFECT OF ROTATION AND TEMPERATURE ON THE INHIBITION
PERFORMANCE OF CASHEW (ANACARDIUM OCCIDENTALE L.)
NUT SHELL LIQUID ON CO2 CORROSION OF CARBON STEEL
Buchweishaija, J. and Mkayula, L.L
Chemistry Department, University of Dar es Salaam,
P.O. Box 35061, Dar es Salaam, Tanzania.
E-mail: buchwe@chem.udsm.ac.tz

ABSTRACT
A natural extract of cashew nut shells, Cashew Nut Shell Liquid (CNSL) was
investigated as a corrosion inhibitor for carbon steel in 3% NaCl solutions saturated with
CO2 gas using electrochemical techniques (i.e. potentiodynamic polarization and ac-
impedance). The investigation was performed at different temperatures under static and
dynamic conditions using a Rotating Disk Electrode (RDE). It was found that CNSL
reduces the electrochemical processes taking place on carbon steel undergoing corrosion.
The percentage inhibitor efficiency increases with increase in CNSL concentration and
decreases with rise in temperature. Betterb performance at low CNSL concentration was
registered under dynamic conditions and room temperatures. Thus CNSL is a potential
corrosion inhibitor for carbon steel undergoing corrosion in CO2 medium.
Keywords: Corrosion; Corrosion inhibitor; Carbon dioxide; Carbon steel

				
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