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Articles 61 - 73 of 73

Full-Text Articles in Other Operations Research, Systems Engineering and Industrial Engineering

An Optimization Tool For A Standalone Photovoltaic System, Johanes Kasilima Apr 2024

An Optimization Tool For A Standalone Photovoltaic System, Johanes Kasilima

Tanzania Journal of Engineering and Technology (TJET)

Stand-alone photovoltaic systems (SAPV) are often used in remote areas where access to grid electricity is limited. This system depends on solar energy. However, Photovoltaic (PV) systems need a greater initial investment than conventional sources of energy, and their effectiveness is reliant on a number of environmental conditions such as the unpredictable solar radiation. One step in reducing the investment cost of a PV system is determining the optimal size of solar PV components that minimize costs. This paper presents a Particle Swarm based optimization tool for sizing Stand-alone PV systems. The optimization tool selects the optimal Levelized Cost of …


Optimal Load Shedding During Service Restoration In Electrical Secondary Distribution Network Based On Reinforcement Learning, Rukia J. Mwifunyi Apr 2024

Optimal Load Shedding During Service Restoration In Electrical Secondary Distribution Network Based On Reinforcement Learning, Rukia J. Mwifunyi

Tanzania Journal of Engineering and Technology (TJET)

Increased stress in traditional power systems results in blackouts due to voltage instability attributed to a mismatch between available capacity and load demand, especially in distribution networks. Service restoration schemes are designed to return power supply to the affected parts of the networks. The availability of insufficient supply is a complex problem that requires operational experience or an automatic system. The stochastic nature of load demand significantly impacts service restoration as it results in increased restored demand in case a fault occurs during off-peak hours and helps reduce overload if the fault occurs during peak hours. The study adopts an …


Design And Optimization Of An Azeotropic Distillation Pilot Plant For The Production Of Pure Ethanol, Samwel V. Manyele Apr 2024

Design And Optimization Of An Azeotropic Distillation Pilot Plant For The Production Of Pure Ethanol, Samwel V. Manyele

Tanzania Journal of Engineering and Technology (TJET)

This study aimed to design an azeotropic distillation plant using Aspen Plus® V10 software and determine optimal process conditions for producing pure ethanol greater than 95% from pre-concentrated near-azeotropic ethanol-water solution. The non-random two-liquid Redlich-Kwong thermodynamic model was the base method for property analysis and performance prediction. Modelling and simulation of the converged process were conducted for fixed column variables (R = 5, N = 12 and p = 1 atm). Plant operating parameters were varied in the range of 0 to 1 for the pre-heater vapour fraction, 2 to 10 for the column feed plates (NFP), 2 to 6 …


Effect Of Zr And W Doping On Microstructures, Transition Temperature And Solar Transmittance Modulation Of Thermochromic W/Zr Co-Doped Vo2 Thin Films, Haji F. Haji Apr 2024

Effect Of Zr And W Doping On Microstructures, Transition Temperature And Solar Transmittance Modulation Of Thermochromic W/Zr Co-Doped Vo2 Thin Films, Haji F. Haji

Tanzania Journal of Engineering and Technology (TJET)

Thermochromic W/Zr co-doped VO2-based thin films with different concentrations of Zr were successfully deposited on soda lime glass substrates by direct current (DC) magnetron sputtering of V(99)W(01) alloy and Zr targets at a substrate temperature of 425 °C. The films were characterized by x–ray diffraction (XRD), atomic force microscopy (AFM), Rutherford backscattering spectroscopy (RBS), two-point probe and UV/VIS/NIR spectroscopy. The film’s structural properties evolution was significantly influenced by Zr concentration in the films. The transition temperature and hysteresis loop widths of the films were found to decrease with increasing Zr concentration. For the Zr concentrations of 0.21 at.%, 0.23 at.% …


Causes And Consequences Of Inefficient Drilling And Blasting In Mine Development Headings: A Case Study Of Hard Rock Gold Mining Operations In Northern Tanzania, George Bennett Apr 2024

Causes And Consequences Of Inefficient Drilling And Blasting In Mine Development Headings: A Case Study Of Hard Rock Gold Mining Operations In Northern Tanzania, George Bennett

Tanzania Journal of Engineering and Technology (TJET)

Despite the introduction of the perimeter blasting technique at the Tulawaka Gold Mine, the mine continued to suffer from an overbreak of mine development headings, with an average overbreak of 24% every 22 m, which is approximately twice the acceptable 10% overbreak. The causes of this problem include ineffective drilling practices and uneven and excessive charging of explosives, resulting in a slightly high powder factor of 3.94 kg/m3 instead of 3.8 kg/m3, as per the design. The problem of overbreak resulted in ore dilution, a longer mine development cycle time and additional costs of approximately US$ 45 per cut, especially …


Ambient Air Emission Profiles Of Polycyclic Aromatic Hydrocarbons Around A Typical University Power House In Nigeria, Oyetunji Okedere Nov 2023

Ambient Air Emission Profiles Of Polycyclic Aromatic Hydrocarbons Around A Typical University Power House In Nigeria, Oyetunji Okedere

Tanzania Journal of Engineering and Technology (TJET)

The level of electricity generation in Nigeria is presently grossly inadequate. Consequently, the productive sectors of the economy do not presently enjoy an uninterrupted supply of electrical energy from the country’s national grid and the downtime is in most cases too much. Using diesel-fueled electric power generators has become an attractive alternative to meet the shortfall in the energy supply gap. In this study, the levels of polycyclic aromatic hydrocarbons in the vicinity of the diesel-fueled electric power generators operated by Osun State University, Osogbo, Nigeria were investigated with a view to ascertain the priority levels and carcinogenic PAHs. Since …


Modelling Monthly Rainfall Of Calabar, Nigeria Using Box-Jenkins (Arima) Method, Francis Ogbozige Jun 2022

Modelling Monthly Rainfall Of Calabar, Nigeria Using Box-Jenkins (Arima) Method, Francis Ogbozige

Tanzania Journal of Engineering and Technology (TJET)

Rainfall has both positive and negative effects on human activities hence, correct prediction of the period of occurrence is very essential. However, the traditional method of predicting months of heavy rainfall is gradually fading out as irregular rainfall pattern is been experienced in most regions of the world. The rainfall pattern in Calabar city in Southern Nigeria has been reported in past literatures of being irregular. Hence, this research applied the Auto-Regressive Integrated Moving Average (ARIMA) also known as Box-Jenkins method to model the rainfall pattern of Calabar. This was achieved by subjecting 50years monthly rainfall (1971 – 2020) to …


In-Situ Observation Of Retained Austenite And Residual Stress Evolutions During Tempering Of Carbonitrided Din 1.6587 Alloy Steel, Richard J Katemi Jun 2022

In-Situ Observation Of Retained Austenite And Residual Stress Evolutions During Tempering Of Carbonitrided Din 1.6587 Alloy Steel, Richard J Katemi

Tanzania Journal of Engineering and Technology (TJET)

This paper investigates the evolution of retained austenite and residual stresses during and after tempering of carbonitrided 18CrNiMo7-6 low alloy steel carried out using in-situ X-ray diffraction technique. In this case, two carbonitriding treatments with different surface the retained austenite contents of 20 and 54 mass.-% are investigated. The tempering is carried out in a continuous heating mode to 650°C as well as in isothermal mode at holding temperature of 170, 240, and 300°C for 2 hours. During continuous heating at a heating rate of 10°C/min, the retained austenite started to decompose at 290°C. On isothermal holding at 170°C for …


Impacts Of Land Cover Change Caused By Urbanization On The Flood Regime Of Msimbazi Catchment In Dar Es Salaam, Tanzania, Chrisogonous Kibugu, Subira Munishi Jun 2022

Impacts Of Land Cover Change Caused By Urbanization On The Flood Regime Of Msimbazi Catchment In Dar Es Salaam, Tanzania, Chrisogonous Kibugu, Subira Munishi

Tanzania Journal of Engineering and Technology (TJET)

The hydrological processes of a catchment are the function of climate, land use and land cover. Changes in either climate or land use or land cover can result in alteration of the catchment’s hydrological processes. In the recent past, Msimbazi catchment in Dar es Salaam has undergone drastic land cover changes mainly due to urbanisation. These land cover changes caused changes in the behaviour of river flow resulting in frequent floods. Therefore, this study analyses the impacts of the changes in land cover due to urbanisation specifically with the changes in river flow, surface run-off and base-flows. Previously generated land …


Spatial And Temporal Variation Of Selected Water Quality Parameters In The Tanzanian Side Of Lake Victoria, Richard Joseph Kimwaga Feb 2022

Spatial And Temporal Variation Of Selected Water Quality Parameters In The Tanzanian Side Of Lake Victoria, Richard Joseph Kimwaga

Tanzania Journal of Engineering and Technology (TJET)

Lake Victoria’s water quality is increasingly becoming under heavy pressure mainly due to land based activities and aerial inputs which are taking place within the basin. This study was carried out to assess the spatial, including vertical and temporal, variation of the water quality of Lake Victoria on the Tanzanian side. Historical water quality data for the period from 2000 to 2016 was collected. Temperature, pH, Dissolved Oxygen (DO) and Turbidity were selected for study since they are the mostly measured and monitored water quality parameters. Land use-land cover changes were analysed using ArcGIS. ILWIS 3.7 software was used to …


Review Of The Product Development Process And Information Flow In The Manufacturing Industry: Problems And A Possible Wav Forward, E Opiyo Jun 2004

Review Of The Product Development Process And Information Flow In The Manufacturing Industry: Problems And A Possible Wav Forward, E Opiyo

Tanzania Journal of Engineering and Technology (TJET)

No abstract provided.


Application Of Vibrational Techniques In Determination Of Dynamic Properties Of Agricultural Products-State Of The Arton Of Vibrational Techniques In Determination Of Dynamic Properties Of Agricultural Products-State Of The Art, Silas Kajuna Dec 1999

Application Of Vibrational Techniques In Determination Of Dynamic Properties Of Agricultural Products-State Of The Arton Of Vibrational Techniques In Determination Of Dynamic Properties Of Agricultural Products-State Of The Art, Silas Kajuna

Tanzania Journal of Engineering and Technology (TJET)

Vibration is one of the techniques employed in the determination of dynamic properties of fruits and vegetables. It entails generation of a mechanical or acoustic vibrational signal which is propagated through the flesh of the agricultural material. A transducer is either attached or held close to the specimen to monitor the propagation of the signal through the specimen. The manner in which the signal is transmitted through the material is analyzed, and the dynamic properties of the specimen which relate to its firmness or its internal being are derived. The technique has been around for the past 30 years or …


Strategic Transformation Of Public Enterprises In Tanzania: Action Research Oriented Methodology, M A.M Victor Dec 1999

Strategic Transformation Of Public Enterprises In Tanzania: Action Research Oriented Methodology, M A.M Victor

Tanzania Journal of Engineering and Technology (TJET)

Naturally, enterprises are dynamic in the sense that they can either grow or shrink. Growth is the wish of all owners and particularly of fast growth. We talk of growth here as both increasing the speed of circulation of the working capital profitably and increasing the size or expansion of the fixed assets through retained earnings. Proper management will in most cases assure a gradual growth. However, in some situations, gradual growth may not be sustainable due to global competition and/or some other political changes such as elimination of monopoly. In these situations, enterprises will need a strategic transformation, not …