Aeromagnetic data over part of the Abakaliki Lower Benue Trough has been evaluated to estimate the geothermal energy potential and model the morphology of the basin through assessing the depth to the magnetic basement and modeling prominent magnetic anomalous bodies. The data were acquired, analyzed, and interpreted. Qualitative analysis, using visual inspection of Total Magnetic Intensity (TMI), Residual Anomalous (RAM), and Analytical Structural (ASM) maps, shows that the majority of faults trend east-west, while few others orientate in the NNE to SSW directions. The visual assessment of TMI and RAM maps reveals high magnetic intensities ranging from 6700 to 7505 nT and -100 to 250 nT, respectively. Areas with high magnetic values suggest lower sedimentary infilling, while areas with lower magnetic values suggest thicker sedimentary covers. The western part of the research area exhibits structural alteration around the Ishiagu, Enyigba, and Eziagu regions. There is evidence of intrusive bodies around Obubura and Onyen in the southeast region of the research area. The quantitative results show two depth sources: the deep sources range from 10.71 to 21.88 km, and the shallow sources range from 2.52 to 9.45 km. The deeper sources suggest further depth to the geothermal contact sources. The sediment accumulation pattern from the basin morphological map reveals uneven, undulating, and structurally controlled depositional patterns across the entire research area. The results also show a linear depression with sedimentary accumulation trending northwest-southeast. The 3D subsurface basal configuration map reveals uplifting and depression, which is a distinctive expression of folds. The average sedimentary infilling thickness and the geothermal gradient are 8.2 km and 13.9°C/km, respectively. The correlation between heat flow and geothermal gradient shows linear relationships, implying that areas of higher heat flow correspond to regions of higher geothermal energy. Key words: Fourier transform, sedimentary infilling, depth modeling, basin morphology, geothermal energy.
Concrete has remained challenging to replace for an extended period due to its inherent strength and minimal maintenance needs over the lifespan of structures, coupled with its versatile applications in various infrastructure projects such as foundations, superstructures, and more. Additionally, concrete components, including fine crushed rock and river sand, are readily accessible in the environment. Recently, waste crumb rubber tyres have emerged as a readily available aggregates option. A True Experimental Research Design method was employed in this study. Concrete was prepared using cement, coarse crushed rock, fine crushed rock, and water, without the use of admixtures, additives, or any other agents, in order to exclusively assess the impact of waste crumb rubber tyres on both fresh and hardened properties. Crumb rubber concrete (CRC) was created by substituting waste crumb rubber tyres for natural fine crushed rock in ratios of 0, 10, 20, 30, and 40% by weight, within the range of 0 to 2.36 mm. Among the CRC samples studied in this research, 10-CRC, which denotes concrete where 10% of the fine aggregates is replaced with waste crumb rubber tyres, exhibited the best performance. This determination was based on its workability, air content, unit weight, compressive and flexural strength, and rate of water absorption. Key words: Concrete, environment, aggregates, crumb rubber, tyres, fresh, hardened.
Examining the spatial relationship of surface temperature and Normalized Difference Vegetation Index (NDVI) in the urban center helps to balance heat island effect and creates sustainable urban environment. This study identifies the relationship between vegetation condition and surface temperature of Addis Ababa over various land use/cover (LU/LC) types. For this purpose, Landsat 8 OLI and TIR sensor data which were obtained in a dry season are used. The Land Surface Temperature (LST) of the area was retrieved by having surface emissivity that was derived from NDVI threshold method. The LST result of the city shows that the surface temperature of the city varied from 291.61 to 313.06 Kelvin (K). Within the city a significant change in surface temperature was observed over various LU/LC types, which is inversely proportional to their respective vegetation condition. The highest surface temperature and the lowest NDVI were registered on paved surfaces, bare land and settlement areas have lower NDVI value respectively. Whereas, forest and vegetative areas have low surface temperature and high NDVI as compared to the other land use and land cover types. Following the poor distribution of healthy vegetation in the city, the surface temperature varied from the center of the city where it has low NDVI in settlement areas to the peripheral zones. Therefore, to create a livable urban environment, we need sufficient land development regulation which should be friendly to the urban climate such as adding to the numbers of green places in parcels and city level that can attribute to the betterment of the climatic condition in the settlement area. Key words: Addis Ababa, Ethiopia, Landsat 8, Land Surface Temperature (LST), Normalized Difference Vegetation Index (NDVI).
This article examines the impact of integrating basalt aggregates into concrete based on Typha australis for housing applications. We conducted an experimental study focusing on mechanical and thermal characterization to analyze the influence of basalt aggregates compared to the results of previous work on T. australis concrete without basalt. The results indicate that both density and mechanical resistance to compression decrease with the dosage of Typha, yet the values obtained are significantly higher than those of concrete without basalt. Additionally, thermal resistance increases with the Typha dosage. However, for low Typha dosages, the thermal resistance is slightly higher than that of concrete without basalt, whereas for high dosages, it is slightly lower. Nevertheless, this finding allows for a reduction in the building's thermal load and an enhancement of thermal comfort. However, it's important to note that the mechanical strength remains relatively low for a high-strength structure. Key words: Lightweight concrete, Typha australis, basalt aggregates, density, mechanical resistance, thermal resistance, thermal load, thermal comfort.
Nine Regional Aeromagnetic data sheets from the Lower Benue Trough, Nigeria have been interpreted using the centroid and forward modelling technique of spectral analysis with the aim of delineating structures that can possibly control mineralization within the trough.The residual magnetic map was analyzed using the geological cross-section to determine the number of anomalies and the Fourier transform method was used to estimate the depth to the top and bottom of the anomaly, the analytical signal amplitude, the first vertical derivative, Rose diagram and power spectrum.From the spectral analysis results, the estimated depth value to the top of the anomalous body ranges from 0.5 km to about 12 km, with the highest depth to the top of the anomaly located within the south-western and north-western axis of the study area.The estimated depth to the bottom of the anomalous body ranges from about 20 to 50 km with the highest depth located within the north eastern axis of the study area.The analytical signal amplitude map highlights the discontinuities or boundaries of the anomalous (granitic) body.It also enhances variations in the magnetic properties of the magnetic sources within the study area.The analytical signal amplitude map gave figures that range from 0.001 to about 0.047 nT/m.The map of the first vertical derivative depicts the near surface geological features such as fold, faults and geological structures within the trough.It is observed from the map of the first vertical derivative that most of the structures are trending in NE-SW (northeast to southwest), while some trends in NW-SE (northwest to southeast) directions.The major fault in the study area trends E-W (east to west) direction and these trends also conform to the trends indicated by the Rose diagram.The study also identified areas of high sedimentary thickness which could favour accumulation of hydrocarbon within the trough.
The study investigates the electro-geophsysical method's application to assess corrosivity, competence, and aquifer vulnerability in Njaba and its environs, in southeastern Nigeria, aiming to determine soil suitability for engineering constructions and estimate aquifer vulnerability. Urbanization in the area has led to increased man-made structures and surface pollution exposure. Twenty-three geo-electric resistivity soundings were conducted using ABEM Terameter SAS-4000 and Schlumberger configuration with a maximum half-current electrode spacing of 500 m. Results indicate undulating topography with elevations ranging from 361 to 1336.9ft. Soil resistivity assessment reveals 43.5% moderate competence, 26.1% competent, and 26.1% highly competent zones, with the remainder exhibiting incompetent clay lithology. Corrosivity assessment shows 73.9% essentially non-corrosive and 26.1% mildly corrosive topsoil. The study identifies a semi-deep aquifer system with depths ranging from 79.2 to 115 m and thickness from 23.4 to 48.5 m. Aquifer resistivity ranges from 28700 to 990 Ωm, indicating clean sand to sand with clay admixtures. Hydraulic conductivity varies from 0.0852 to 27.90068 m/day, suggesting clean sand. Aquifer vulnerability assessment indicates a high to moderately low protective capacity, making most of the area suitable for engineering construction and groundwater development. The study highlights the reliability of geological and geo-electric methods in delineating hydraulic conductivity and lithostratigraphic units. It recommends corrosion-resistant pipes in mildly corrosive areas to prevent pipe rupture within a depth of approximately 1.1 m. Keywords: Competence, corrosivity, hydraulic conductivity, aquifer vulnerability.
In this study we investigate the different temperature electronic energy band structure responses of silicon, germanium and gallium arsenide at various applied hydrostatic pressures within a range that does not exceed their structural phase transition pressure. The pressure coefficients for each material have been determined. An atomistic insight was presented into the question of how much of the electronic band structure deformation, due to hydrostatic pressure, originates from the valence or the conduction bands. It was observed that the rate of increase in energy of the conduction band minimum with an increase in pressure is greater than that of the valence band maximum for Ge and GaAs, while it is less than that of the valence band maximum for silicon. The origin of this negative value of the first order pressure coefficient of silicon was explained in terms of p and d conduction band orbitals coupling at the Xc high symmetry point of the Brillouin zone, hence exhibiting quantum level repulsion between them, thus forcing the conduction band edge downwards in energy relative to the maximum of the valence band at Tc. The hydrostatic volume deformation potential, ag is found to be constant for Ge and GaAs. Our results agree with the "empirical rules of pressure coefficients" for inter-band electronic transitions of types Tv → Tc in gallium arsenide, Tv → Lc in germanium and Tv → Xc in silicon. Key words: Hydrostatic deformation potential; pressure coefficients; inter-band electronic transitions; orbital coupling; quantum level repulsion.
