Groundwater Potential Mapping in Lapan Gwari Community Using Integrated Remote Sensing and Electrical Resistivity Soundings

This research aims to address the pressing issue of failed and abandoned wells, causing water scarcity in Lapan Gwari Community, through an improved groundwater exploration approach integrating remote sensing and electrical resistivity soundings. The study area, located within the Zungeru Sheet 163 SE, spans Latitudes 9°30'00"N to 9°32'00"N and Longitudes 6°28'00" to 6°30'00". The surface geologic, structural, and hydrogeological mapping provided essential insights into the hydrogeological framework. Leveraging SRTM DEM data, thematic maps were created for geomorphology, slope, land use, lineament density, and drainage density. These datasets were then integrated using ArcGIS to develop a preliminary groundwater potential zones map. Further investigations were conducted using Vertical Electrical Sounding (VES) and Electrical Resistivity Imaging (2D VES) surveys at targeted locations identified by the preliminary map. Results show that the study area predominantly consists of crystalline rocks of the Nigerian Basement Complex, primarily comprising schist and granite with minor occurrences of quartz vein intrusions. Surface joint directions indicated a dominant NE-SW trend. The VES data revealed three to four geoelectric layers, encompassing the topsoil (1 to 5 m depth, resistivity: 100 Ωm to 300 Ωm), the weathered layer (in the 3-layer system) or fractured layer (in the 4-layer system), and the fresh basement rock characterized by infinite resistivity. The shallow weathered layers (3 to 30 m thickness) are believed to hold aquiferous potential. Hydrogeological interpretation, facilitated by 2D resistivity models, delineated water horizons trapped within clayey sand and weathered/fractured formations. Notably, the aquifer resistivity range was found to be between 3 - 35 m and 100 - 300 Ωm, signifying a promising aquifer positioned at depths of 40 to 88 m. This aligns with corroborative static water level measurements. Given this, we recommend drilling depths of a minimum of 80 m to ensure the acquisition of sufficient and sustainable water supplies. The final groundwater potential zones map derived from this study is expected to serve as an invaluable guide for prospective groundwater developers and relevant authorities in formulating effective water resource management plans. By effectively tackling water scarcity challenges in Lapan Gwari Community, this integrated approach demonstrates its potential for application in similar regions facing comparable hydrogeological concerns.

Decoding brain responses to pixelized images in the primary visual cortex: implications for visual cortical prostheses

Visual cortical prostheses have the potential to restore partial vision. Still limited by the low-resolution visual percepts provided by visual cortical prostheses, implant wearers can currently only ＂see＂ pixelized images, and how to obtain the specific brain responses to different pixelized images in the primary visual cortex（the implant area） is still unknown. We conducted a functional magnetic resonance imaging experiment on normal human participants to investigate the brain activation patterns in response to 18 different pixelized images. There were 100 voxels in the brain activation pattern that were selected from the primary visual cortex, and voxel size was 4 mm × 4 mm × 4 mm. Multi-voxel pattern analysis was used to test if these 18 different brain activation patterns were specific. We chose a Linear Support Vector Machine（LSVM） as the classifier in this study. The results showed that the classification accuracies of different brain activation patterns were significantly above chance level, which suggests that the classifier can successfully distinguish the brain activation patterns. Our results suggest that the specific brain activation patterns to different pixelized images can be obtained in the primary visual cortex using a 4 mm × 4 mm × 4 mm voxel size and a 100-voxel pattern.

Logging identification method of depositional facies in Sinian Dengying Formation of the Sichuan Basin

The sedimentary facies/microfacies,which can be correlated with well logs,determine reservoir quality and hydrocarbon productivity in carbonate rocks.The identification and evaluation of sedimentary facies/microfacies using well logs are very important in order to effectively guide the exploration and development of oil and gas.Previous carbonate facies/microfacies identification methods based on conventional well log data often exist multiple solutions.This paper presents a new method of facies/microfacies identification based on core-conventional logs-electrical image log-geological model,and the method is applied in the fourth member of the Dengying Formation(Deng 4)in the Gaoshiti-Moxi area of the Sichuan Basin.Firstly,core data are used to calibrate different types of facies/microfacies,with the aim to systematically clarify the conventional and electrical image log responses for each type of facies/microfacies.Secondly,through the pair wise correlation analysis of conventional logs,GR,RT and CNL,are selected as sensitive curves to establish the microfacies discrimination criteria separately.Thirdly,five well logging response models and identification charts of facies/microfacies are established based on electrical image log.The sedimentary microfacies of 60 exploratory wells was analyzed individually through this method,and the microfacies maps of 4 layers of the Deng 4 Member were compiled,and the plane distribution of microfacies in the Gaoshiti-Moxi area of the Sichuan Basin was depicted.The comparative analysis of oil testing or production results of wells reveals three most favorable types of microfacies and they include algal psammitic shoal,algal agglutinate mound,and algal stromatolite mound,which provide a reliable technical support to the exploration,development and well deployment in the study area.

Forward and inverse problem for cardiac magnetic field and electric potential using two boundary element methods

This paper discusses the forward and inverse problem for cardiac magnetic fields and electric potentials. A torso-heart model established by boundary element method （BEM） is used for studying the distributions of cardiac magnetic fields and electric potentials. Because node-to-node and triangle-to-triangle BEM can lead to discrepant field distributions, their properties and influences are compared. Then based on constructed torso-heart model and supposed current source functional model-current dipole array, the magnetic and electric imaging by optimal constrained linear inverse method are applied at the same time. Through figure and reconstructing parameter comparison, though the magnetic current dipole array imaging possesses better reconstructing effect, however node-to-node BEM and triangleto-triangle BEM make little difference to magnetic and electric imaging.

High-speed 3D imaging based on structured illumination and electrically tunable lens

In this Letter, we present a high-speed volumetric imaging system based on structured illumination and an electrically tunable lens（ETL）, where the ETL performs fast axial scanning at hundreds of Hz. In the system,a digital micro-mirror device（DMD） is utilized to rapidly generate structured images at the focal plane in synchronization with the axial scanning unit. The scanning characteristics of the ETL are investigated theoretically and experimentally. Imaging experiments on pollen samples are performed to verify the optical cross-sectioning and fast axial scanning capabilities. The results show that our system can perform fast axial scanning and threedimensional（3D） imaging when paired with a high-speed camera, presenting an economic solution for advanced biological imaging applications.