Digital Commons Network^™

Integrating Gis With Interim Payment Valuation In Road Construction Projects: A Conceptual Framework, Abdulrahman I. Iro, Juma M. Matindana, Julian Ijumulana

Tanzania Journal of Engineering and Technology (TJET)

Abstract

Interim Payment Valuation is a critical process in road construction contract administration, yet conventional valuation practices remain heavily dependent on manual measurements, fragmented documentation, spreadsheets, and professional judgement. These limitations can affect measurement accuracy, transparency, traceability, and the timeliness of payment certification. Although Geographic Information Systems have increasingly been applied to construction planning, quantity measurement, progress monitoring, infrastructure management, and decision support, their integration with contractual and financial processes for interim payment valuation remains insufficiently explored. This study therefore develops a conceptual framework for integrating GIS with Interim Payment Valuation in road construction projects. A PRISMA-guided structured literature review …

A Tool For Assessing The Effectiveness Of Speed Humps As Traffic Calming Measure, Abdulrazak Mzamiru Kachwamba, Enock W. Nshama

Tanzania Journal of Engineering and Technology (TJET)

Urban population growth and increasing motor vehicle usage continue to raise concerns regarding road safety in rapidly developing cities. Although previous studies have assessed traffic-calming effectiveness using multiple criteria, they have analysed the criteria separately and have not developed a composite tool for classifying overall effectiveness. This study develops a quantitative assessment tool designed to compute a weighted composite score for evaluating the effectiveness of speed humps as a traffic calming measure. Stakeholder questionnaire responses, complemented by descriptive analysis and exploratory factor analysis, were used to identify key indicators of effectiveness and the variables influencing them. Findings indicate that speed …

Artificial Neural Network-Based Modelling And Prediction Of Key Performance Indicators In Road Construction Projects, Hussein Mativila, John M. Kafuku, Beatus A. T. Kundi

Tanzania Journal of Engineering and Technology (TJET)

Road construction projects in developing countries including Tanzania experience several challenges including cost overruns, schedule delays and poor quality. The causes of these challenges include complex interdependencies project’s uncertainty factors. This makes traditional methods for predicting Key Performance Indicators (KPIs) less effective. This study has developed a robust Artificial Neural Network (ANN) model for accurate modelling and predicting KPIs for road construction projects in Tanzania. The analysis was based on data obtained from 281 projects implemented by TANROADS in 11 regions from 2015 to 2025. Fourteen uncertainty factors were measured on a five-point Likert scale and screened using Principal Component …

Voltage-Related Power Quality Issues And Impacts On Distribution Networks With Sensitive Loads - A Review, Godwin Elinazi Mnkeni, Jackson Justo, Aviti Thadei Mushi, Bakari M. M. Mwinyiwiwa

Tanzania Journal of Engineering and Technology (TJET)

Voltage disturbances are the most important power quality (PQ) complications that customers and power utilities face in this smart era. The growing adoption of sophisticated electronic equipment and integration of renewable energy sources (RES) into power grids has increased the susceptibility of power distribution networks (PDNs) to voltage sags, swells, interruptions, flicker, and voltage imbalance. These disturbances, mainly caused by upstream faults, switching operations, and RES integration, compromise voltage PQ and system reliability. Consequently, they accelerate equipment degradation, increase electronic waste (e-waste), raise reactive power demand and maintenance costs, increase power losses, and impose substantial economic losses on customers and …

Disturbance-Learning Inertia Estimation Using Artificial Neural Networks For Power System Stability, Sospeter Igaanja Gabriel, Francis Mwasilu, Peter Makolo Dr.

Tanzania Journal of Engineering and Technology (TJET)

ABSTRACT

Power systems are progressively shifting towards low inertia as a result of incorporating significant amounts of intermittent and converter-based renewable energy sources, such as wind and solar power, into the current power grid network. This integration poses considerable problems to inertia and frequency control within the network due to a reduction in the proportion of synchronous generators. Furthermore, rapid frequency deviations occur due to the disparity between supply and demand during contingencies, complicating the maintenance of frequency stability within the power system. The disturbance-learning inertia estimation method for power system stability is presented. The simulation analysis is performed using …

Fast Sparse Image Reconstruction Models In Through-The-Wall Radars: A Review, Aude Kileo, Hashimu U. Iddi, Abdi Abdalla

Tanzania Journal of Science

Through-the-Wall Radar Imaging (TWRI) is a modern technology that uses electromagnetic waves to detect objects behind walls, with key applications in surveillance, rescue operations, and reconnaissance. Achieving high resolution in both down-range and cross-range requires ultra-wideband signals and long apertures, resulting in large data volumes, increased acquisition time, and high memory demands. TWRI employs Compressive Sensing (CS) to reduce computational time, which has proved its significance in many recent TWRI applications. However, in CS, image reconstruction approaches shift the computational burden from the sensing stage to the recovery stage, which prolongs the reconstruction times, making it unsuitable in time-sensitive applications. …

Feasibility Of Acetylated Icacina Trichantha Oliv. Tuber Starch As Viscosity And Fluid Loss Control Agents In Water-Based Drilling Mud. A Comparative Assessment With Commercial Starch, Kennedy I. Ogunwa, Theresa O. Uchechukwu, Ozioma Achugasim, Leo C. Osuji, Onyewuchi Akaranta

Tanzania Journal of Science

The need for sustainable, non-food drilling fluid additives has prompted the feasibility assessment of acetylated Icacina trichantha tuber starch as a viscosity modifier and fluid loss control agent in water-based muds. Native starch was acetylated to obtain two derivatives (Degree of Substitution DS = 0.38 and 0.68) and characterized using FTIR, swelling power, and physicochemical analyses. Drilling mud performance was assessed through rheology, gel strength, filtration loss, sorptivity, and model fitting. Acetylation improved swelling and reduced gelatinization temperature. The optimal formulation, Mud-ITO-ACS2 (DS = 0.68), exhibited the most favorable performance, combining low plastic viscosity (6 cP vs 9 cP for …

Biosensor Development In East Africa: A Systematic Review Of Technologies, Applications, Challenges, And Future Directions, Ally Mahadhy

Tanzania Journal of Science

Biosensors integrate biological recognition elements with signal transduction systems to generate quantitative or semi-quantitative analytical information and have applications across healthcare, food safety, agriculture, environmental monitoring, and wildlife health. Despite substantial global advances, biosensor development in East Africa remains poorly characterized. This systematic review, conducted according to PRISMA 2020 guidelines, evaluated published evidence from 1995 to 2025 within a predefined East African Community geographical scope. Eligibility was based on IUPAC-aligned operational criteria requiring an integrated biological recognition element, transduction mechanism, and quantitative or semi-quantitative signal output. Three locally developed biosensors met the criteria: an electrochemical nano-biosensor for schistosomiasis diagnosis in …

Effect Of Acid Pretreatment On The Adsorption Of Phenol Red By Cellulose Isolated From Sandbox (Hura Crepitans L.): Kinetics, Isotherms And Thermodynamics, Muibat O. Alabi-Abass, Najeem A. Adesola Babarinde, Adeola A. Ibikunle, Nurudeen O. Sanyaolu

Tanzania Journal of Science

The removal of synthetic dyes from wastewater remains an urgent environmental concern due to their persistence and toxicity. This study evaluates cellulose from Hura crepitans (HC) and its acid-modified form (AHC) for the adsorption of phenol red (PR) dye from aqueous solutions. The adsorbents were characterized using FTIR to identify functional groups responsible for dye binding, XRD to determine the crystalline structure, SEM to examine surface morphology, and BET/BJH analyses to measure surface area and pore distribution. Acid modification enhanced surface roughness, porosity, and the abundance of active functional sites, leading to improved adsorption efficiency. Optimal conditions were pH 9.0 …

Hybrid Transformer-Bilstm Model For Early Fault Detection And Multiclass Classification Of Wind Turbine Faults Using Scada Data, Hassan Y. Mkindu

Tanzania Journal of Engineering and Technology (TJET)

Early and accurate fault detection in wind turbines is essential for improving operational reliability, reducing maintenance costs, and minimizing unplanned downtime. This study proposes a Hybrid Transformer-BiLSTM deep learning model for early fault detection and multiclass fault classification using Supervisory Control and Data Acquisition (SCADA) data. The proposed architecture combines the Transformer's self-attention mechanism to capture global temporal dependencies with the Bidirectional Long Short-Term Memory (BiLSTM) network's ability to model sequential fault evolution, enabling effective learning of multivariate time-series data. The model was developed and evaluated using the recently introduced CARE SCADA dataset, classifying five operating states: No Fault, Transformer …

A Quad-Port Dual-Band Elliptical Patch Mimo Antenna For 5g And Wlan Applications, Livingstone L. Kimaro, Hashimu Uledi Iddi, Mussa M. Kissaka, Neema S. Joseph

Tanzania Journal of Engineering and Technology (TJET)

A dual-band multiple-input multiple-output (MIMO) antenna for wireless local area network (WLAN) and fifth-generation new radio (5G NR) band n104 applications is presented. Two U-shaped slots interconnected back to back are etched on an elliptical shaped patch, four identical patch elements are then arranged orthogonally to form a quad-port antenna that resonates at 5.8 GHz and 6.7 GHz. Without additional extrinsic decoupling structures, the proposed design achieves measured isolation levels above 25.13 dB and 21.31dB, realized gains of 7 dBi and 7.2 dBi and -10 dB impedance bandwidths of 155.4 MHz and 90 MHz in the lower and upper frequency …

Design Of Permanent Magnet Synchronous Motor For Railways Traction Application, Anna S. Mwang'onda, Jackson J. Justo, Francis Mwasilu

Tanzania Journal of Engineering and Technology (TJET)

This paper presents the design of surface mounted permanent magnet synchronous motor (SMPMSM) intended for traction applications in standard gauge railway (SGR) for passengers. The proposed motor is rated 350 kW with a base speed of 3000 rpm. Moreover, speed control strategy with stability analysis is incorporated in the design to validate the performance of the SPMSM. The simulation results achieved a torque of approximately 1115 Nm at a terminal voltage of 800 V. The flux linkage of 150 mVs which ensures effective electromagnetic pertinence while maintaining safe magnetic loading because the flux density is less than 1.5 T. The …

Recent Advances In Bioethanol Production From Water Hyacinth: A Critical Review, Umuamina A. Matola, Mahir Mohammed Said, Olga-Ioanna Kalantzi, Abraham K. Temu

Tanzania Journal of Engineering and Technology (TJET)

Water hyacinth (WH) is a highly invasive tropical aquatic weed with high holocellulose and low lignin content, making it a promising lignocellulosic feedstock for second-generation bioethanol production. Producing bioethanol from WH offers a sustainable approach to simultaneously managing invasive biomass and producing renewable energy. This review critically evaluates recent advancements in bioethanol production from WH by examining pretreatment, hydrolysis, and fermentation technologies reported between 2014 and 2024. A PRISMA-guided literature search was conducted using the Scopus and Web of Science databases, and fifty-nine original research articles were selected for analysis. The reviewed studies were comparatively assessed based on pretreatment strategies, …

Exploring Consultancy-Related Variations In Public Building Projects: A Review Towards A Management Framework, Grayson Bambaza, Ismail W. R. Taifa, George S, Mwaluko

Tanzania Journal of Engineering and Technology (TJET)

Consultancy-related variations remain one of the leading causes of cost overruns, schedule delays, quality deficiencies, and contractual disputes in public building projects. Although various studies have been undertaken to document the causes of variations in construction works, the same level of interest has not been shown for consulting services variations across the consulting services spectrum and their consequences for effective management. This study explores variations in consulting services for public works by systematically reviewing the existing literature using the PRISMA (Preferred Reporting Items for Systematic reviews and Meta Analyses) guidelines. Relevant articles published from 2020 to 2026 were retrieved from …

Urban Spatial Development Control In Tanzania: Analysis Of Factors Influencing Gis Application Using Structural Equation Modelling (Sem)., Happiness Protas Mmanda, Nestory Yamungu

Tanzania Journal of Engineering and Technology (TJET)

Rapid urbanization in developing countries has intensified urban expansion, creating challenges for sustainable development. Geographic Information Systems (GIS) enhance spatial planning, but empirical evidence on factors influencing their effectiveness remains limited. This study examines determinants of GIS application in Urban Spatial Development Control (USDC). The objectives are to (1) identify and categorize factors affecting GIS use, (2) assess relative strength, and (3) develop a validated structural model explaining GIS adoption in USDC. Data were collected from 103 LGAs by a mixed sampling method. Exploratory and Confirmatory Factor Analysis classified influencing factors into technology-related (α = 0.869, CR = 0.881), process-related …

Decision Support Tool For The Maintenance Of Meter Gauge Railway Permanent-Way Infrastructures: A Concept Paper, Hamisi J. Maulid, Beatus A.T Kundi, Juma M. Matindana, Ismail W. R. Taifa Dr

Tanzania Journal of Engineering and Technology (TJET)

A Decision Support Tool (DST) represents a transformative way of modernising maintenance practice on the permanent-way infrastructure of Meter Gauge Railway (MGR). Maintenance practice remains largely reactive, as the MGR plays a strategic role in transporting both freight and passengers, resulting in inefficient resource allocation, high operational risk, and growing Lifecycle expenses. This concept paper explores the potential and the design challenges for a DST that combines fuzzy analytic hierarchy process (Fuzzy-AHP) modelling, multi-criteria decision analysis (MCDA), Geographic Information Systems (GIS) and predictive machine learning (ML) analytics for evidence-based, future-oriented maintenance management. The paper draws on peer-reviewed studies from …

Effect Of Sugarcane Bagasse Ash Incorporated With Limestone Calcined Clay Cement On Geotechnical Properties Of Swelling Soils Relevant To Road Applications, Horris K. Nangulama, Siya P. Rimoy, John E. Elvis

Tanzania Journal of Engineering and Technology (TJET)

This study aims to investigate the use and effect of sugarcane bagasse ash (BA) incorporated with limestone calcined clay cement (LC³) as a sustainable and cost-effective alternative for stabilizing swelling soils. Therefore, BA incorporating LC³ was added to black cotton soil (BCS), known for its high swelling potential. Series of laboratory tests including free swell index (FSI), compaction, California bearing ratio (CBR), and shear strength were conducted to evaluate the performance of BA incorporating LC³ binder-stabilized BCS. Additionally, microstructural analyses using pore size distribution (PSD), X-ray diffraction (XRD), and scanning electron microscopy (SEM) were performed to …

Flexible Power Point Tracking For Active Frequency Regulation In Grid-Connected Photovoltaic Power Plants, Castor K. Haule, Sophia D. Kigodi, Emmanuel S. Matee, Francis Mwasilu

Tanzania Journal of Science

The increasing penetration of photovoltaic (PV) systems into modern power grids necessitates advanced control strategies capable of supporting grid stability. Traditional PV systems rely on Maximum Power Point Tracking (MPPT) to maximize energy extraction, limiting their ability to participate in grid-support functions such as frequency regulation or power curtailment. This paper presents a flexible power point tracking (FPPT) control strategy that enables PV systems to operate at arbitrary points along the power–voltage (P–V) curve. A multi-mode power management scheme is proposed, integrating conventional Perturb and Observe (P&O) MPPT with FPPT, allowing the system to switch dynamically between energy maximization and …

Optimization Of Gas Consumption, Cost And Production Rate For Computerized Numerical Control Oxy-Acetylene Flame Cutters, Eustace K. William, Simon I. Marandu, Enock W. Nshama

Tanzania Journal of Science

This study examined the impact of flame cutting parameters (i.e., cutting speed, plate thickness and nozzle diameter) on oxy-acetylene gas consumption, cost and production rate. A full factorial design of experiments was used to generate 27 experiments, which were conducted using a CNC flame cutter. The analysis of variance (ANOVA) method was used to determine significant process parameters, followed by regression analysis using the MINITAB ® software. The technique for order preference by similarity to ideal solutions (TOPSIS) was used to determine the optimal cutting parameters for minimizing the consumption and cost estimation of oxy- acetylene gas and maximizing the …

Mitigation Of Power Quality Problems In Songwe Power Distribution Line Using A Static Distribution Compensator, James Mhame, Emmanuel Matee, Francis Mwasilu, Sophia D. Kigodi

Tanzania Journal of Science

The Songwe electrical distribution system is prone to severe voltage drops that lead to frequent power outages in long feeders, light flickering, and the multi-operation of equipment and other appliances. The voltage at the switching station averaged 27.6 kV, 28.21 kV, and 25.79 kV in the years 2023, 2022, and 2021, respectively. Additionally, the maximum was 32.2 kV, below the nominal voltage, and the feeder has a very low power factor, which drops to 0.6 during peak hours. Currently, TANESCO uses automatic voltage regulators connected to a distant location from the switching station to two feeders with critical voltage drop …

Improving The Concrete Compressive And Flexural Strength With A Low Fraction Addition Of Carboxylated Nitro-Oxidized Cellulose Nanofibrils From Banana Rachis, Ngesa Ezekiel Mushi, Emmanuel Kagya

Tanzania Journal of Science

Conventionally, concrete strength depends on the bonding interface, especially in hydrated products such as calcium silicate hydrate (CSH). As a result, concrete is sensitive to tensile load. With its unique properties, a low fraction of carboxylated nitro-oxidized cellulose nanofibrils (NOCNF) from the banana rachis is employed to improve the mechanical performance of the concrete nanostructurally. Compressive and flexural strength using the NOCNF content at 0, 0.05, and 0.1 wt.%, cured for 7 and 28 days, were evaluated. Notably, the compressive strength increased by 16 % and the flexural strength by 13 % at 0.1 wt.% NOCNF compared to plain concrete …

Assessment Of The Radionuclide Concentration Levels Of Water And Sediments Along The Mara River, Gasper Kachenge, Abubakary Salama, Abdalah Kileo, Furaha Chuma

Tanzania Journal of Science

For many years, several factors have impacted the water quality of the Mara River, including population growth, agricultural expansion, livestock keeping, mining, and industrial activities. These factors have intensified water pollution and climate change effects around the river. While previous studies have mainly focused on assessing heavy metal pollution risks on the Mara River, this study evaluates the concentration levels of radionuclides in boreholes, water, and sediments along the river and its tributaries. Naturally occurring radioactive materials, including 226Ra, ²³²Th, and ⁴⁰K, were evaluated. A high-purity germanium radiation detector (HPGe) with a coaxial detector system coupled with Gamma Vision software …

The Role Of Zinc Precursor Concentration In Modulating The Structural, Optical, And Electrical Properties Of Sol-Gel Derived Czts Thin Films, Justine John Tibaijuka

Tanzania Journal of Science

This study reports on CZTS thin films fabricated by sol–gel spin coating using zinc acetate dihydrate, copper acetate dihydrate, tin chloride, and thiourea dissolved in methanol with monoethylamine as a stabilizer. The films were annealed rapidly at 540 °C by using an RTP furnace. Results show the significant influence of zinc concentration on films’ properties with band gap evolution between 1.46 and 1.7 eV, along with high absorption coefficients exceeding 10⁴ cm⁻¹ in the visible range. Structurally, the films evolved from poorly crystalline at low Zn content to well- crystallized, (112)-oriented kesterite near stoichiometry. However, excessive Zn caused slight degradation …

Joint Channel And Phase Noise Estimation For Mmwave Ofdm Systems Using Adaptive Kalman Filtering, Kwame Salum Ibwe

Tanzania Journal of Science

This manuscript presents a joint channel and phase-noise estimation framework for millimeter-wave (mmWave) OFDM systems based on an adaptive extended Kalman filter (EKF). The proposed method formulates a unified state-space model that simultaneously tracks time-varying multipath channels and oscillator phase noise, a critical impairment in 5G NR frequency range 2 (FR2) and emerging 6G transceivers. An innovation-based covariance adaptation mechanism is introduced to enhance estimation accuracy while maintaining computational efficiency. Simulation results demonstrate that the proposed approach achieves up to a 5 dB SNR gain at a target BER of 10⁻³, maintains NMSE below 10⁻³ for linewidths up to 200 …

Hybrid Solar - Coal Thermal Energy System For Industrial Process Heat At Sayona Drinks Limited In Tanzania, Santos Kihwele, Elisha D. Bitesigirwe

Tanzania Journal of Engineering and Technology (TJET)

Over the past two decades, global efforts to mitigate pollution from conventional energy sources have intensified, with coal remaining a major contributor to carbon emissions. While fossil fuels cannot be eliminated from thermal generation in manufacturing industries, particularly in middle‑income countries such as Tanzania, they continue to dominate as the primary energy source. Industries including food and beverage, paper, textile, paints, chemicals, and pharmaceuticals require substantial thermal energy for heating and drying, and typically rely on coal and natural gas.This study introduces a unique application of a parabolic trough solar thermal system with integrated thermal energy storage, specifically tailored to …

Compact Low-Profile Dual-Band Microstrip-Fed Monopole Antenna For Wlan And Lte Applications, Hashimu U. Iddi

Tanzania Journal of Engineering and Technology (TJET)

The rapid advancement in wireless communication technologies has led to rising user demand for high-speed data transfer, seamless connectivity, and improved wireless communication efficiency. Therefore, it is inevitable to develop efficient and compact antennas which can support different frequency bands of various wireless system standards in mobile devices. A compact, low-profile microstrip-fed monopole antenna operating in dual bands, 2.45 GHz and 5.8 GHz, and suitable for WLAN and LTE applications is proposed in this study. The proposed antenna’s radiating element was carefully designed using slotting techniques and optimising the various parameters for achieving the required resonance frequency. The proposed compact, …

Trajectory-Based Model Predictive Control For Rotary Crane Sway Suppression With Only Horizontal Boom Actuation, Haryson J. Nyobuya

Tanzania Journal of Engineering and Technology (TJET)

Safety is of biggest importance in construction and industrial activities involving rotary cranes. These cranes are huge and responsible of moving large parts or/and materials from different positions. Now operating these cranes tend to be subdue to pay load oscillations when moving the load for which is extremely dangerous when not suppressed. This study proposes the generation of trajectory using Model predictive control approach with reduced control horizon compared to state horizon. Reduced control horizon design reduces computational time for trajectory generation while maintaining the pay-load sways to a minimum. In this approach the complex dynamic model is reduced to …

On The Use Of Lorawan For Smart Fishing Applications In The Blue Economy Sector, Eva Shayo

Tanzania Journal of Engineering and Technology (TJET)

The growth of digital technology is expected to transform small-scale fishery sectors, where a need for robust, low-cost, long-range communication networks becomes critical. There exist several technologies that are used in the fishery sector but they are never affordable to small scale fisheries. This study evaluates the feasibility of using low cost Long Range Wide Area Network (LoRaWAN) technology specifically tailored for smart fishing environments to small scale fishery sector. Using simulation, we assess the performance of the key performance metrics including probability of success and energy efficiency under varying device densities and time. During evaluation, we considered end devices …

Optimal Design And Techno-Economic And Environmental Analysis Of A Hybrid Solar Pv-Battery-Generator System For Off-Grid Telecom Towers And Rural Households: Case Of Misughaa Village In Tanzania, Ibrahim Mwammenywa, Martha Mwaikenda

Tanzania Journal of Engineering and Technology (TJET)

Telecommunication services are pivotal for the socio-economic development of communities, regions, and countries. Extensive and reliable telecom infrastructure enables populations to leverage development opportunities and bridge the urban-rural divide. However, extending these services to rural areas often necessitates the deployment of telecommunication towers in locations lacking national grid access. Consequently, service providers typically rely on diesel generators (DG) for power, which introduces significant challenges. These challenges include a high operational expenditure (OPEX), rendering telecom services unaffordable for rural communities, and substantial environmental pollution from greenhouse gas (GHG) emissions. This study aims to present an optimal design, encompassing sizing and economic …

Physicochemical Properties And Chemical Compositions Of Cashew Nut Shell Liquid Extracted With Carbon Dioxide–Expanded Hexane, Neema Msuya, Joseph Yn Philip, Frank Jacob, Kando K. Janga

Tanzania Journal of Engineering and Technology (TJET)

Cashew nut shell liquid (CNSL) is a mixture of phenolic compounds that can effectively replace commercially available phenols in various applications. This study investigated the physicochemical properties and chemical composition of CNSL extracted using CO₂–expanded hexane (CXH) and compared to the traditional Soxhlet extraction method. Steamed cashew nut shells (sCNS) were used in both cases.  The CXH was carried under varying CO₂-mole fractions (0.468-0.892) and temperatures (20-36 °C) whereas Soxhlet extraction was performed at atmospheric pressure and hexane boiling point. Response Surface Methodology (RSM) with Central Composite Face-Centred Design (CCFD) was employed to evaluate the effect …