FUOYE Journal of Engineering and Technology (FUOYEJET - Federal University Oye-Ekiti)
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Some Thermodynamic Properties of White Yam (Dioscorea rotundata) Slices Dehydrated in a Refractance WindowTM Dryer
Get PDFThe objective of this study is to estimate the changes in Enthalpy, Entropy and Gibbs Free Energy of yam slices dehydrated at different temperatures using a Refractance WindowTM dryer. Dehydration of 1.5, 3.0 and 4.5 mm thick yam slices, was performed with water temperatures of 65, 75, 85 and 95oC in the flume of a Refractance WindowTM dryer. During the dehydration operations, the moisture-content history data were recorded. For the process conditions considered, the moisture content history data was used to calculate the moisture diffusivity and the activation energy of dehydration of the samples. Subsequently, changes in Enthalpy, , Entropy, , and Gibbs Free Energy, ), were calculated. For the process conditions studied, the changes in, , , and, varied from 20,381.33 to 25,217.05 J.mol-1., -140.69 to -122.29 J.mol-1.K-1.and 67,934.80 to 70,220.15 J.mol-1, respectively. This study is essential as knowledge of these thermodynamic parameters are useful for the optimal design and sizing of preservation dryers for argo-products. Keywords— Enthalpy; Entropy; Gibbs Free Energy; Refractance WindowTM Dryer; Yam
A Framework for Sustainable Maintenance of Offshore Energy Structures
Get PDFThis paper proposes a structure for maintenance decision support suitable for application to renewable energy assets. The method combines subjective tacit knowledge of subject-area experts with well-structured Analytical Hierarchical Process (AHP) to elicit weights of criteria relevant for effects evaluation of possible failures modes towards support for component’s maintenance decisions. The Technique for Ordered Preference using Similarity to Ideal Solution (TOPSIS) algorithm is adopted for aggregating the evaluation scores and achieving priority indexing given the conflicting characteristics of some criteria. Part of the highlights of the Framework is the implementation of the group experts, as well as individual expert's elicitations in a complimentary manner that eliminates subjective opinions and achieves a repeatable evaluation score. The conclusion of the analysis is the prioritisation of the component’s failure; An indicative case study of offshore wind turbine jacket support structure is used to demonstrate the applicability of the approach and the analysis results-which shows priority failure modes for focused maintenance intervention as bending of Chord/Brace ( ), collapse of Chord/Brace ( ), buckling of Long piles ( ), and Truss( ), overturning of Skirt pile ( ), and fatigue of Long pile ( ), further demonstrates the capacity of the model to support maintenance decisions. Caution is exercised in the selection of criteria that would capture the objectives of the risk analyses by consulting wide range of industry experts. Keywords— AHP, Expert, Offshore energy, TOPSIS, Wind turbine Support Structur
Minimizing Interference in Ultra-Dense Femtocell Networks Using Graph-Based Frequency Reuse Technique
Get PDFThis paper investigates the performance of graph colouring schemes for frequency assignment in Long-Term Evolution (LTE) networks with ultra-dense femtocells. The aim of the study is to minimize interference in such networks while ensuring efficient spectrum use for these femtocells. The three schemes investigated are the conventional greedy graph colouring algorithm, the saturation degree algorithm and our proposed graph-based theory (GBT) algorithm. The process of frequency assignment is similar in the last two except that the proposed GBT partitions the femtocells into independent sets for an efficient frequency re-use. The performance of these three schemes was analyzed through extensive simulations to determine the SINR and network capacity that can be obtained with the deployment of these schemes using the ITU-R P1238-7 path loss model. The outcome of this study showed that with the absence of a dynamic frequency assignment scheme, interference level is increased as the number of femtocell users within a particular coverage is increased, leading to a reduction in the capacity of such networks. Simulation results showed that all three algorithms considered have the ability to allocate frequencies to femtocells and minimize interference in a densely deployed environment, thereby increasing network capacity. The proposed GBT assigned the least sub-band thereby ensuring spectral efficiency while minimizing harmful interference. Results show that the greedy algorithm has a disadvantage of inefficiently assigning sub-bands randomly, while the saturation degree assigns more sub-bands when compared with the GBT scheme.Keywords — Femtocell, graph colouring, frequency assignment, LTE
Assessment of Water Availability and Demand in Goronyo Reservoir Sokoto, Nigeria
No full textClimatic parameters are subjected to variation due to atmospheric concentration of greenhouse gases, so it is essential to assess the water availability and demand under the climate variation in Goronyo reservoir since supply of water is one of the significant tasks in water resources management. In this study, estimation of available water, demand and unmet demand was simulated using Water Evaluation and Planning (WEAP) Software with the opinion of assessing the availability of the water for it use under climate change. Firstly, the climatic data was obtained and used to simulate the surface water situation with the model. Secondly, the data was projected based on the initial model output and compared with the existing (observed) data. The comparison involved calibration and validation with the recorded data of river flow. Thirdly, the hypothetical climate change Scenarios were applied to the model so as to know what is to be expected if climate changes. Thus, the model was used to analyse what happened to demand and water availability in the study area. The study found the demand and Unmet demand as the output of the model, and the result showed that the annual total demand for various uses from 2018 to 2070 is 7076.4 million cubic meters (MCM) and annual average of 133.4 million cubic meters (MCM). Meanwhile, the unmet demand ranges from annual total of 1157.5 million cubic meters to 1199.7 million cubic meters and annual average of 21.84 MCM to 22.64 MCM. From the result the highest unmet was recorded under the worst scenario i.e. scenario 9 with 1.2oC increase in temperature and 10% decrease in precipitation. In Conclusion, it was found that the demand in the area is 6 times higher in years to come i.e. 50 years from now and deficit is 61% increased.Keywords – Climate variation, Goronyo Reservoir, Water Demand and Unme
Development of a Wheelchair Automator
No full textThe first wheelchair model could be traced to the 5th, 6th and later in 18th century. However, tremendous development and great achievements in this field started mid of 20th century. Since that time, varieties of models have been designed, leading to wide range of products. This work involves the development of an automator (ergonomically attachment) to convert a manual wheelchair into an electric wheelchair for domestic use by Nigerian physically disabled people who could not pay the high cost of a ready-made motorized or an electric-powered wheelchair. A gear motor and drive system has been integrated in this automator for convenience and easy control for the user. Two units of 12v batteries and breaking system has also been integrated into this work and by this, obtained an automatic wheelchair which can be driven with the possibility of avoiding obstacles by the use of the obstacle detection components. In addition, obstacle detection component is also incorporated to the system to serve as added alert feature in case the wheelchair is been used by a blind user. The automator which is attached to the wheelchair has been developed to enhance easy and long distance movement. It helped the disabled move around without external interference. A manual wheelchair does not give sufficient mobility, it has a limited range and is very difficult to use on rough and harsh terrain. This work is designed as a solution to this problem by combining the comfort and maneuverability of a wheelchair with the capability and efficiency to move about. This work will benefit the physically challenged people.Keywords—Automator, obstacle detection, electric-powered wheelchair, wheel chair, mobility.
Direct Solution of Second Order Ordinary Differential Equations Using a Class of Hybrid Block Methods
No full textThis research proposes the derivation of a class of hybrid methods for solution of second order initial value problems (IVPs) in block mode. Continuous linear multistep method of two cases with step number k = 4 is developed by interpolating the basis function at certain grid points and collocating the differential system at both grid and off-grid points. The basic properties of the method including order, error constant, zero stability, consistency and convergence were investigated. In order to examine the accuracy of the methods, some differential problems of order two were solved and results generated show a better performance when comparison is made with some current methods.Keywords- Block Method, Hybrid Points, Initial Value Problems, Power Series, Second Order
Preparation and Water Absorption Properties of Parinari polyandra Fruit Shell Reinforced Epoxy Composites
No full text— The need to protect the environment has led to renewed research interest in sustainable bio-based materials such as natural fibre-reinforced polymer composites. Parinari polyandra (Benth) fruit shell (PPFS) is a woody biomass residue that is scarcely explored. This work reports the use of parinari as the fiber reinforcement in epoxy resin matrix biocomposites. The biocomposites were prepared from 2mm sized particles using hand layup method and by varying fibre contents from 0 to 40 wt %. The biocomposites affinities for water were determined by short and the long term water absorption tests according to ASTM standards. Water absorption capabilities of the biocomposites increased with increasing fibre contents while 10 wt% fibre content gave excellent moisture resistance property. The lowest water absorption of 0.01 and 0.2% for short term and long term tests respectively occurred in the 10 wt % filler content which compared very well with the control at short term test. PPFS is hereby suggested as a suitable natural filler material for bio-epoxy composite with desirable water absorption resistance properties.Keywords— Agricultural waste, Biocomposites, Parinari, Water absorption, West Afric
Anti-Corrosion Behaviour of Silver-Cobalt Oxide-Titanium Dioxide Nanocomposites Coated Mild Steel in Sea water
No full textThe research work investigates the corrosion resistance of Silver-Cobalt Oxide-Titanium Dioxode (Ag/Co3O4/TiO2) nanocomposites coated mild steel (AISI 1020) in seawater environment. The coatings were carried out by dipping method. The nanoparticles were individually produced by mixing the salt precursors with extract of Piptadeniastrum africana leaf under the optimized synthesis conditions. The Ag/Co3O4/TiO2 nanocomposite was produced by mixing Ag, Co3O4 and TiO2 NPs in equal proportions to constitute 75 wt% of the composite. 10 wt % epoxy resin and its hardener in the ratio (1:1) were added to serve as the binder, while 15 wt% of CNT was introduced to serve as support. Phase and Microstructural examination of the coatings was carried out by XRD and HRSEM. The corrosion protection properties were determined by using computer- controlled EGG 273A Potentiostat with three- electrode cell system under static laboratory conditions using the linear potentiodynamic polarization method. The coated sample was dried at temperatures of 100oC to enhance adherence of the coating on the steel substrate. The result of Tafel polarization plots revealed improved corrosion resistance of the coated specimen as compared to as-received sample. Corrosion rate and corrosion resistance of 0.201 m/y and 195.12 Ω were recorded against the coated sample while 0.261 m/y and 71.42 Ω were recorded for the as-received sample respectively. The coated sample exhibited higher potential shift in the positive direction and showed better corrosion resistance properties.Keywords- Nanocomposite, Mild steel, Corrosion, Potentio-Dynamic polarization, Seawater
Performance Evaluation of the Effect of Sodium Hydroxide on Geotechnical Properties of Lateritic Soil for Rural Road Construction
No full textThis study explored the potentials of sodium hydroxide (NaOH) for the improvement of the properties of lateritic soil (LS) intended for use as construction material for rural roads in the North-eastern part of Nigeria. The soil was classified as A-6(13) and CL according to the American Association of State Highway and Transport Officials (AASHTO M 145-2012) and the Unified Soil Classification System (ASTM D 2487-2011). The soil is treated to evaluate the effectiveness of NaOH in treating lateritic soil with 1, 3 and 7 molar concentration of NaOH and compacted using two methods of compaction, the British Standard Light (BSL) and British Standard Heavy (BSH). Unconfined compressive strength (UCS) and Californian bearing ratio (CBR) tests were conducted on the compacted specimens. The results obtained show a general improvement in the engineering properties of the soil with increase in molar concentration of NaOH, particularly, when compacted at the BSH energy level. The maximum 7 days UCS values of 909 kN/m2 and 1106 kN/m2 were obtained at 7 molar concentration for the BSL and BSH energy levels. These values are within the range of 750 – 1500 kN/m2 UCS value specified by the Nigerian General Specification (2013) for sub-base materials. In the case of the CBR, at 3 and 7 molar concentrations for BSH effort, CBR values of 33% and 38% were recorded while 34% CBR value was recorded at 7 molar concentration for BSL effort, these values also met the minimum requirement of 30% CBR specified by the Nigerian General Specification for sub-base construction.Keywords— Lateritic, Sodium hydroxide, Soil, Rural roads.
Microstructure and Mechanical Characterization of Austempered AISI 1018 Steel
Get PDFAISI 1018 mild steels are widely used for engineering applications in machine components and for structural purposes. These materials suffer mechanical damages especially when used under critical conditions of extreme load. In this study, the effect of austempering heat-treatment on the hardness, tensile strength, impact energy and the microstructure of AISI 1018 steels were evaluated. The steel specimens were subjected to austempering heat-treatment by austenitizing at a temperature of 830°C, maintained at this temperature for a period of 1 hour 30 minutes, before rapidly cooled down in a NaNO3 salt bath maintained at 300°C for isothermal transformation for a further 50 minutes before finally cooled down to room temperature. Microstructural analysis using Scanning Electron Microscope (SEM) shows transformation from ferrite/pearlite to bainite microstructure. The tensile strengths of the specimen increased from 400 MPa to 500 Mpa; hardness increased from an average value of 140Rc to 162Rc; while impact energy increased from 15.6 Joule to 30.6 Joule by the austempering heat-treatment. Keywords—Austempering, hardness, tensile strength, impact energy, microstructur