Arid Zone Journal of Engineering, Technology and Environment (AZOJETE)
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Towards Sustainable Road Infrastructure Delivery in Nigeria
Get PDFDue to current Federal Government infrastructure transformation policy agenda and economic development growth, there is a lot of pressure on Nigeria’s infrastructure, especially on roads. The construction of roads is capital intensive requiring long-term financial supports. The aim of this paper is to investigate the theory and practice that adopt sustainability concept at road and general infrastructure delivery in Nigeria. Multi-Criteria Decision Model or Method was used (Weighted Sum Model) for sustainability index. The mathematical model for computing the sustainability index in achieving the required result was formulated. Additionally, a cognitive/reasoning map system was used as decision aid. The result shows that sustainability criteria and indicators are chosen based on the project specific or regional priorities or needs. The study also showed that there is no systematic method of sustainability appraisal in Nigerian construction industry. It proposed both multi-criteria method of analysis and cognitive/reasoning map because of their mathematical foundation and practical applications, and recommends that sustainability drivers should be integrated with their different perceptions and priority needs. It also recommended the introduction of Sustainability Impact Assessment
Influence of Tungsten Inert Gas Welding on Hardness, Tensile Strength and Microstructures of Aluminum 6061 Alloy Weldments
Get PDFIn this work, tungsten inert gas (TIG) welding was used for joining aluminum 6061 alloy because it offers low heat input to the weld joints and the ability to remove any refractory oxides such as Al2O3 through a process known as the cathodic cleaning effect. This research was carried out to evaluate the level of improvement in the tensile strength and the hardness of aluminum 6061 alloy welds, using a tungsten inert gas welding approach. Aluminum 6061 alloy in form of a round bar of length 100 mm and 8 mm in diameter was first machined to the standard tensile testing specimen according to the American society for testing and materials (ASTM) using a lathe machine. It was then butt welded along the center of the bar using tungsten inert gas welding process with a constant welding current of 18 Amperes and gas flow rate of 15 liter/min. the same process was repeated for both the hardness and microstructure specimens followed by butt welding along the center of the specimen. The welded samples were then subjected to the hardness and tensile testing using Rockwell hardness testing and Hounsfield tensile testing machine respectively. The results showed that the welded metal and the heat-affected zone possessed the highest hardness value of 84.2 HRB and 71.9 HRB respectively as compared with the parent metal with a hardness value of 66.8 HRB. Also, the tensile strength of the welded specimens is 300.35 N/mm² which is relatively lower than that of the base material with a tensile strength of 348.67 N/mm². Additionally, the results of the microstructural examination reveal the presence of trace aluminum oxides within the matrix of the welded structure which indicates the slight increase observed in the hardness of the welded sample as compare to that of the base material. Therefore, the hardness and tensile strength for the welded sample are close to the base metal indicating that welding of aluminum and its alloys using the TIG welding process gives welds of adequate mechanical properties.
 
Modification, Fabrication and Performance Evaluation of Insulated Box for Post-Harvest Handling of Fish
Get PDFIn order to address the challenges associated with postharvest handling of fresh fish, Nigerian Stored Products Research Institute (NSPRI) developed an insulated transportation mechanism named Ice Fish Box™ which has a capacity of 18 kg of fish and ice. However, capacity and ease of movement was encountered in the developed box leading to modification using a smaller box (inner box) of dimension 495 mm×340 mm× 340 mm fitted into a bigger box of dimension 540 mm×360 mm× 360 mm and a trolley on wheels using human muscle power for ease of movement. The construction was carried out using standard procedures and all materials used were sourced locally. Results of its performance tests indicated that the modified box can carry approximately 60 kg of fish and ice at full load and the trolley can carry load of up to 120 kg of stacked boxes and swerves easily at angle 45º. It is expected that these modifications would allow for more storage of fish and ease movement on all terrains as handlers mostly women find it almost difficult in moving the earlier designed insulated box around.
 
Performance Evaluation of 200W Solar Photovoltaic Panel Considering Bauchi Microclimatic Conditions.
Get PDFMeasurement and modeling of broadband and spectral terrestrial solar radiation is important for the evaluation and deployment of solar renewable energy systems. This paper focuses on optimizing the performance of 200W solar module taking into consideration the local climatic conditions of Bauchi locality. The uncertainty in life cycle savings for solar thermal and photovoltaic (PV) systems as linearly correlated with uncertainty in solar resource data. These uncertainties paved way for the need to conduct a critical assessment of the resource. Assessment of the solar resource for these technologies rely upon measured data, where available. In this paper, we present the development of mathematical model of photovoltaic solar cells based on their detailed single diode equivalent circuit representation. Pertinent simulation models for PV solar module both for an ideal weather situation and for taking into consideration the effects of microclimatic conditions that prevail in Bauchi as evaluated and compared with benchmarks available. The complete model of the PV system was implemented using MATLAB/Simulink platform. The standard characteristic curves for the 200W solar panel are as presented. The simulation of the ideal PV system made use of standard test conditions (STC) to facilitate comparison with the existing benchmark results in the literature. The analysis of the characteristics performance curves returned an average VOC = 42.9v and ISC = 4.21A. The simulation results further revealed that the power delivered by the 200W monocrystalline solar module of 144.3W @620W/m2, 35ºC as recorded for Bauchi under all climatic conditions as evaluated. The benchmark values obtained in the laboratory are VOC = 45.5V, ISC = 5.92A and 200-W under the Standard test condition (STC) conditions of cell temperature 25ºC, solar irradiance of 1000W/m2 and air mass (AM) of 1.5. The average conversion efficiency and fill factor as evaluated are 0.77 and 16% respectively. This result agrees with the benchmark of module efficiency of >15.66% recorded at STC. The results conclusively reveal that the microclimate of a locality essentially affects the performances of solar PV systems deployed to each location on the globe. Therefore, utilization of these parameters is essential for consideration in the design of solar systems in all localities
Framework for Investigating Contractor Selection Decision Support Systems’ (CS-DSS) Acceptance by Public Procurement Personnel
Get PDFLaboratory-based designs of contractor selection decision support systems (CS-DSSs) are common in construction management research. However, target end-users like the public procurement entities do not usually make use of these ubiquitous technologies in practice, in spite of their enormous potentials. The absence of reliable framework for investigating technology adoption in public procurement has continued to impede the possibilities of investigating the acceptance of such technologies. The present study aims at developing a framework for investigating CS-DSS acceptance for the smallest decision making unit in public procurement. The structure of a novel theoretical techno-psychological framework for investigating CS-DSS acceptance in Nigerian public procurement is presented in this paper through the lens of an extended innovation diffusion theory - technology acceptance model (IDT-TAM). From an individual level remit (micro-level), a strategic review of literature was followed by a Delphi survey of carefully selected 18-number procurement experts in Nigeria. The study shows that the prescriptions of CS-DSSs by researchers can be supported by a foresight on the end-user behavioral intension to use such technologies. Operationalization of the framework with empirical data can model the acceptance behavior of procurement personnel on CS-DSSs before they are adopted at the organizational or strategic level for enhanced contractor selection in public procurement. The emerging framework is recommended for designers of CS-DSS for articulating the antecedent behavior of public procurement personnel.
 
Fabrication of Probe Trap for Monitoring Cowpea Weevil Infesting Stored Cowpea
Get PDFInsect probe traps are effective in detecting grain insects but neglected because it is time consuming and precise method of interpreting the catch have not been adequately specified. Interestingly, this is not readily available in Nigeria and where available, it is expensive due to foreign exchange rates. Therefore, there is need for a locally available and more acceptable insect probe trap for integrated pest management practice during postharvest handling of cowpea. Locally sourced materials were used to fabricate a probe trap for monitoring Callosobruchus maculatus (Coleoptera: Chrysomelidae) infesting stored cowpea. The fabricated probe trap was evaluated together with a standard probe trap. Treatments were repeated three times, and also tried in three different insect densities (3, 7 and 15 insects per kg respectively) artificially infested into 10 kg cowpea grains contained in plastic storage buckets, and traps were inspected after every 24 hours for five days. The probe trap was also evaluated in 100 kg cowpea sample contained in sack bag to determine the effect of grain volume on the performance of the trap. Data collected were subjected to ANOVA and means were separated using Student Newman Keuls test (SNK) at 5 % confidence level. The result of total trap catches revealed that the fabricated traps’ mean catch (36.6) was significantly (P ≤ 0.05) higher than the standard probe trap which had lower trap catch mean (12.7) value. Thresholds for management decisions were also determined and the fabricated trap was found to be economically profitable (N 936.75 cheaper); hence, objectives of the study were achieved. It is recommended for cowpea handlers in Nigeria to use the fabricated insect probe trap because it is effective in monitoring beetles, it is less expensive and also locally available.
 
Best-Fit Probability Distribution Model for Annual Monthly Maximum Rainfall in Calabar City, Nigeria
Get PDFThe choice of a suitable model that could predict the possibility of occurrence of rainfall event of a specified magnitude depends mainly on the characteristics of rainfall data at a particular site. This study was aimed at determining the best-fit probability distribution model for annual maximum monthly rainfall. Fifty years rainfall data (1969-2018) obtained from Nigerian Meteorological Agency (NIMET), Calabar, were collated to form an annual series ranked in a decreasing order of magnitude. The data were then evaluated with 6 probability distributions namely; Normal, Log-Normal, Pearson Type III, Log-Pearson Type III, Gumbel Extreme Value Type I and Log-Gumbel probability distributions. The best-fit probability distribution model at the study area was selected based on the results of 4 goodness of fit tests namely; Mean Absolute Deviation Index (MADI), Chi-Squared ) test, Root Mean Square Error (RMSE) and Relative Root Mean Square Error (RRMSE). The performance of the 6 distributions were ranked and the total scores of 8, 23, 16, 12, 21 and 4 were allocated to Normal, Log-Normal, Pearson Type III, Log-Pearson Type III, Gumbel Extreme Value Type I and Log-Gumbel probability distributions, respectively. The results indicate that the best-fit probability distribution model was Log-Normal, which was used to predict rainfall values of 566.8, 664.0, 721.6, 788.1, 834.4, 878.4, 920.7, 974.8 and 1014.4 mm for different return periods of 2, 5, 10, 25, 50, 100, 200, 500 and 1000 years, respectively. It is, therefore, recommended that Log-Normal distribution is the preferred model for frequency analysis of rainfall data for the planning and design of hydraulic structures in the study area. This is necessary for effective flood prevention and mitigation interventions.
 
Thermoplastic Starch Biocomposite Produced from Corn (Zea mays): Comparison of Plasticizers Effects on Mechanical Properties
Get PDFThe excessive reliance on plastic materials made from fossil-fuel based and its ineffective waste management leads to environmental pollution due to their non-biodegradable nature. This study examined the production and testing of bio-composites from Gmelina Arborea wastes and thermoplastic starches as a polymer matrix. Particles of G. Arborea sawdust were obtained from a local sawmill while dry powdered corn starches were sourced from the chemicals market, Ojota, Lagos, Nigeria. Bio-composites were produced by mixing 40 g of corn starch, glycerol/sorbitol, and fractions of prepared G. Arborea (650µm particle sizes) fibre at 0 to 20% (wt/wt of fibre to polymer matrix) were added. The slurries were poured into a mould in accordance with ASTM D638 for tensile strength test samples. The results revealed that the thermoplastic starches, particle sizes, plasticizers, and wood fibre loading significantly affected the tensile strengths, tensile modulus, elongation at break of the bio-composites. Composites produced exhibited tensile strengths values range of 0.35 to 1.75 MPa, modulus of elasticity of 3.10 to 22 MPa, while there was a gradual reduction in elongation at break with a range of 127.4% to 111%. Sorbitol-corn starch generally recorded higher tensile properties of between 1.65 to 1.75 MPa tensile strength than those produced with glycerol plasticizer which ranged between 0.35 to 0.45 MPa as fibre loading increases. It is clear that sorbitol-plasticized bio-composite gives higher values in mechanical strengths when compared to that produced from glycerol.
 
Development of an improved acm scheme for mitigating earth-to-space propagation effects
Get PDFSatellite communication is a promising technology due to its ability to serve very large number of users with high data rate services. The communication link experiences propagation losses such as: Path loss, atmospheric losses, rain fading, ionosphere effects (such as scintillation), and other effects which can greatly affect the received signal strength and close the link budget in the worst case. The design of future broadband satellite systems has to be done with the challenge of more complex traffic mix and these harsher propagation conditions which mitigate the performance of the communications link. Link adaptation (LA) has been used in satellite communications applications for evaluating the performance of an adaptive modulation system in the unique space-based propagation environment. Despite the current research on improving satellite system performance, there is still a need to further develop a scheme that mitigates the effect of atmospheric impairments. This work develops an improved adaptive coding and modulation scheme that mitigates earth-to-space propagation effects. The scheme targets maximizing data throughput while staying below a Bit Error Rate (BER) threshold so as to successfully mitigate link impairment in fixed communication systems. Simulation of the work is carried out using MATLAB 2016b and System Toolkit (STK) 11.
Development of an improved acm scheme for mitigating earth-to-space propagation effects
Get PDFIn satellite communications, the communication link experiences propagation losses such as: Path loss, atmospheric losses, rain fading, ionosphere effects (such as scintillation), and other effects which can greatly affect the received signal strength and close the link budget in the worst case. The design of future broadband satellite systems has to be done with the challenge of more complex traffic mix and these harsher propagation conditions which mitigate the performance of the communications link. Link adaptation (LA) has been used in satellite communications applications for evaluating the performance of an adaptive modulation system in the unique space-based propagation environment. Despite the current research on improving satellite system performance, there is still a need to further develop a scheme that mitigates the effect of atmospheric impairments. This work develops an improved adaptive coding and modulation scheme that mitigates earth-to-space propagation effects. The scheme targets maximizing data throughput while staying below a Bit Error Rate (BER) threshold so as to successfully mitigate link impairment in fixed communication systems. Simulation of the work is carried out using MATLAB 2016b and System Toolkit (STK) 11.3. Simulation result showed that the iACM scheme was able to reduce the effect of path loss in time by 5% over the ACM scheme and also reduced the effect of path loss with respect to the angle of elevation by 2% over the ACM scheme and improvement in the network energy to noise ratio by 22.74% over ACM. In terms of system throughput, the iACM scheme showed an improvement in throughput by 24% over the ACM scheme. Finally, the iACM scheme has shown better performance in terms of throughput and thus, improve the performance of satellite communication