Geophysical investigation on the fracture distribution of Iwo-Olupona Area south-western Nigeria using VLF-EM techniques

This work uses Very Low Frequency Electromagnetic (VLF-EM) method to investigate the subsurface structure on a proposed Housing estate in Iwo, South-Western Nigeria with coordinates 7° 36’ 36.3” N and Longitude ≈ 4° 12’ 06.6” E. The average VLF frequency employed during the field work is 20.8 kHz with average signal strength of 17dBm and the measuring interval of 20m. The data obtained by the VLF-EM method were analysed by 2Dline Plotting. Raw real, R (In phase) and the imagining, I (quadrature) components were measured on the field. The Raw Real and filtered real data were plotted against stations on the same graph using excel, the graphs obtained are sinusoidal in shape with the peak indicating a conductive zones, resulting from weak geologic materials that may be due to fracture, joints, crack, and the trough indicates a non-conductive zones, associated with competent material which may be attributed to fresh basement material or resistive geological formation.Keywords: Fracture, conductive zone, weak zone, structural displacement, frequenc

Geophysical Investigation into the Cause(S) of Structural Failure within Bacosa and Faculty of Science Buildings, Bowen University Temporary Site, Iwo

Cracks on concrete and walls could be bothersome for quality of life and for property claims. Geophysical investigations was carried out around Faculty of Science and BACOSA buildings of Bowen University Temporary site, Iwo with a view to establish the possible cause(s) of failure of buildings within the study area. The geophysical methods used for the investigation were the Very Low Frequency Electromagnetic (VLF-EM) and the Electrical Resistivity (ER) methods. The VLF-EM measurements were taken at an interval of 10m along six traverse lines in the E-W and S-N directions. From the result of the VLF-EM, six VES stations were occupied in the study area involving Schlumberger configuration with half current electrode separation (AB/2) varying from 1 to a maximum of 65m. The 2-D VLF-EM models generated showed a network of suspected linear (geological) structures such as fractures, faults and contacts within the study area. The VES curve types obtained in the area include HA, KH, QH and AA with HA type curve dominating. Four subsurface geologic layers were delineated in the study area. These include the topsoil, weathered layer, clayey sand and fresh basement with resistivity ranging from 121.3 to 771.2 ohm-m, 134.4 to 595.8 ohm-m, 81.6 to 951.9 ohm-m and 1474.7 to 5134.4 ohm-m respectively. The thickness range from 0.5 to 2.4m, 1.8 to 9.8m and2.7 to 24.5m. Depths to the bedrock are generally less than 40m. The resistivity of the weathered layer beneath the topsoil in which the foundation is seated was found to be low within the study area, ranging from 134.4 to 595.8 ohm-m typical of clayey materials. From the models generated from VLF-EM and resistivity data, the distressed structures were found to be situated within the areas with a fairly high concentration of fractures, faults and contacts and relatively low resistivity values(less than 1000 ohm-m) typical of incompetent clayey formation. Keywords: Geophysical investigation, Structural failure, Electrical resistivity, Depth to bedrock, Foundation, Very low frequency electromagnetic, VLF-E

Application of artificial neural network to predict annual global solar radiation for PV system’s sizing in UUM area, Malaysia

The knowledge and estimation of global solar radiation are very crucial in application of photovoltaic (PV) solar system at a particular location. Estimation of global solar radiation at University Utara Malaysia (UUM) area, Malaysia, (Latitude 60N and longitude 1000E) was carried out in this study.The artificial neural network model was used to predict the global solar radiation based on the available simple atmospheric parameters of ambient temperature.The statistical analyses were employed to validate the results obtained from the model.It is deduced from the results obtained that the values of the measured global solar radiation and the estimated values from artificial neural network model have a very close agreement and therefore, have been suggested to be utilized very efficiently in the prediction of the performance of global solar radiation for photovoltaic system application in UUM area and its environs.The values of mean bias error, root mean square error and mean percentage error are 0.00062, 0.00812 and -0.813 respectively.This confirmed the strong capacity of using the model to estimate global solar radiation in the study area for photovoltaic system utilization

Heavy metals' data in soils for agricultural activities

In this article, the heavy metals in soils for agricultural activities were analyzed statistically. Ten (10) soil samples were randomly taken across the agricultural zones in Odo-Oba, southwestern Nigeria. Ten (10) metals; namely: copper (Cu), lead (Pb), chromium (Cr), arsenic (As), zinc (Zn), cadmium (Cd), nickel (Ni), antimony (Sb), cobalt (Co) and vanadium (V) were determined and compared with the guideline values. When the values were compared with the international standard, none of the heavy metals in the study area exceeded the threshold limit. However, the maximum range of the samples showed that Cr and V exceeded the permissible limit which could be associated with ecological risk. The data can reveal the distributions of heavy metals in the agricultural topsoil of Odo-Oba, and can be used to estimate the risks associated with the consumption of crops grown on such soils. Keywords: Agricultural soils, Heavy metals, Contamination, Environment, Soil screening, Geostatistic

Atmospheric dispersion modeling of uncontrolled gaseous pollutants (SO2 and NOX) emission from a scrap-iron recycling factory in Ile-Ife, Southwest Nigeria

In the last decade, government policies promoting foreign investments in the industrial sector particularly for small and medium scale enterprises in Nigeria have led to increased establishment of scrap-iron recycling factories in many states of the federation. Albeit the economic benefits in terms of waste material sourcing and job creation, these scrap-iron recycling factories have attracted significant public criticism due to the characteristic uncontrolled pollution (toxic gases) plume released from their operations into the atmospheric environment of host communities and thus aggravating existing and unresolved rural and urban air pollution problems in Nigeria. This study therefore provides model-based estimates of atmospheric dispersion for gaseous pollutants (SO2 and NOx) released from a scrap-iron recycling factory located in Ile-Ife, southwest Nigeria as a case study for investigating emission signature from such sources. Meteorological parameters measured at the factory location in 2012 and 2013 were used to execute U.S recommended short range (0.01°C/m), very weak winds (90%)

Global Impact of the COVID-19 Pandemic on Stroke Volumes and Cerebrovascular Events: One-Year Follow-up.

Declines in stroke admission, intravenous thrombolysis, and mechanical thrombectomy volumes were reported during the first wave of the COVID-19 pandemic. There is a paucity of data on the longer-term effect of the pandemic on stroke volumes over the course of a year and through the second wave of the pandemic. We sought to measure the impact of the COVID-19 pandemic on the volumes of stroke admissions, intracranial hemorrhage (ICH), intravenous thrombolysis (IVT), and mechanical thrombectomy over a one-year period at the onset of the pandemic (March 1, 2020, to February 28, 2021) compared with the immediately preceding year (March 1, 2019, to February 29, 2020). We conducted a longitudinal retrospective study across 6 continents, 56 countries, and 275 stroke centers. We collected volume data for COVID-19 admissions and 4 stroke metrics: ischemic stroke admissions, ICH admissions, intravenous thrombolysis treatments, and mechanical thrombectomy procedures. Diagnoses were identified by their ICD-10 codes or classifications in stroke databases. There were 148,895 stroke admissions in the one-year immediately before compared to 138,453 admissions during the one-year pandemic, representing a 7% decline (95% confidence interval [95% CI 7.1, 6.9]; p<0.0001). ICH volumes declined from 29,585 to 28,156 (4.8%, [5.1, 4.6]; p<0.0001) and IVT volume from 24,584 to 23,077 (6.1%, [6.4, 5.8]; p<0.0001). Larger declines were observed at high volume compared to low volume centers (all p<0.0001). There was no significant change in mechanical thrombectomy volumes (0.7%, [0.6,0.9]; p=0.49). Stroke was diagnosed in 1.3% [1.31,1.38] of 406,792 COVID-19 hospitalizations. SARS-CoV-2 infection was present in 2.9% ([2.82,2.97], 5,656/195,539) of all stroke hospitalizations. There was a global decline and shift to lower volume centers of stroke admission volumes, ICH volumes, and IVT volumes during the 1st year of the COVID-19 pandemic compared to the prior year. Mechanical thrombectomy volumes were preserved. These results suggest preservation in the stroke care of higher severity of disease through the first pandemic year. This study is registered under NCT04934020