Application of 2D Resistivity Modelling to Delineate Lamproites in Parts of North‑Eastern Dharwar Craton

Geophysical methods have extensively been used in exploration of Lamproite bodies. Lamproites are significant source rocks of primary diamond deposits other than Kimberlites. The Eastern Dharwar Craton is unique in the way that it hosts numerous Precambrian Lamproites confined to the crescent-shaped Paleo-Mesoproterozoic Cuddapah Basin and its north-western and north-eastern margins. In the present study electrical method was used as a tool for delineation of Lamproite bodies in contrast with country rocks in Gundrapally, Vattikode and Marepally regions in parts of the North Eastern Dharwar Craton in Telangana State, India. The electrical profiling method was conducted in different direction to identify the variation of the lithology of the area due to the anisotropic nature and smaller size of the 2-D intrusive bodies adopting the Wenner electrode configuration. The electrical properties of the Lamproites tended to change with their composition due to weathering and the presence of Olivine and K-Al rich composition. The electrical response on the Lamproite pipes is shows a decrease in resistivity concerning the country-rock in the area.

Experimental Study on Electrical Resistivity Characteristics of Saturated Sand Mixes with Bentonite Slurry

Bentonite slurry is widely used in underground and geotechnical engineering because of its strong ability of wall protection. Slurry penetration, which is of great significance for the soil stability, is difficult to observe directly during the soil and slurry interaction. Slurry penetration would change the electrical resistivity of soil, which provides an indirect method to monitor the degree of slurry penetration. This paper aimed to investigate the electrical resistivity characteristics of soil-bentonite mixtures. Several test groups with different material components were carried out. The effects of some factors including water environment, CMC (carboxymethyl cellulose) contents, soil particle gradation, and electrode distance on the electrical resistivity of slurry-soil mixtures were studied and the relationship between soil electrical resistivity and slurry concentration was established. The results in this paper can provide references for the application of the electrical method on slurry penetration.

Selected Problems of Power MOSFETs Thermal Parameters Measurements

In the paper, selected problems that are related to the measurements of thermal parameters of power MOSFETs that are placed on a common heat sink are analysed. The application of the indirect electrical method, the contact method, and the optical method in measuring self and mutual transient thermal impedances of these transistors is presented. The circuits that are required to perform measurements are presented and described. The errors of measurements are assessed for each of the considered methods. In the case of the indirect electrical method, an additional influence of the selection of a thermo-sensitive parameter and the function approximating thermometric characteristics on the measurement error are taken into consideration. The measurement results of the thermal parameters of the investigated transistors that were obtained using the considered measurement methods in various supply conditions are presented and discussed.

The use of a non-invasive electrical method to assess the chemical composition, hardness, and color of durum wheat grain cultivated in an integrated system.

The aim of this research was: (1) to assess the effect of an integrated cultivation system of native durum wheat (6 variants), differentiated by a nitrogen fertilization dose (0, 80, 120 kg.ha-1) and growth regulator use (Medax 350 SC, with growth regulator - GR, without growth regulator - WGR) on changes in selected quality parameters (protein, lipid, and starch contents; hardness; color) and electrical parameters (conductive - Z and capacitive - Cp, Cs) of the grain; and (2) to determine the correlations between the examined quality traits and electrical properties of the grain to indicate the possibility of using a non-invasive electrical method to assess grain quality. The grain of durum wheat cultivated in the six variants tested differed mainly in the starch and lipid contents, which indicates the feasibility of tailored optimization of grain production. The highest contents of starch and total lipids, and the highest grain hardness were obtained in the cultivation variants GR+0N and WGR+0N, whereas the highest protein content - upon wheat fertilization with 120N. The study demonstrated a different strength of the correlations between the tested parameters depending on the cultivation method (WGR-GR; N: 0, 80, 120 kg.ha-1). In the WGR+0N variant (environmentally friendly), the strongest correlation between grain quality traits and electrical properties was obtained for both the conductive (Z) and capacitive (Cp, Cs) parameters in the entire analyzed range of current frequencies. The GR application during cultivation hampers the possibility of using electrical parameters to assess grain quality. In turn, the quality of the grain produced WGR can be effectively assessed using the Z, Cp, and Cs parameters in the entire measuring frequency range (1 kHz-1MHz), while in the variant with GR, only impedance (Z), measured at high frequencies (100 kHz, 1MHz) can be used.

Geo-Electrical Method of Assessment of Coefficient of Permeability and Porosity of Soil of a Poultry Farmland

Leachate collected at the bottom of dead bird’s disposal pits may leak and migrate to pollute groundwater when soils and rocks present are porous. This study assessed the coefficient of permeability (K) and porosity (Ф) of soils and rocks in poultry farmland using 2 Dimensional (2D) electrical resistivity method and soil analysis. Geo-electrical data collection was achieved by using the dipole-dipole array. The field resistivity measurement was carried out along three traverse lines (three Profiles) of 100 m long which were oriented along with East-West directions. These measurements were taken in the order of increasing in offset distance interval of 5 m. The acquired apparent resistivity data were inverted using DIPPROWIN modeling software to perform 2D data inversion. Five soil samples from different locations at depths of 0 – 15 cm and 15 – 30 cm, on the poultry farmland, were collected, transported, and tested in the laboratory. K and Ф were determined using falling head and density methods respectively. The results obtained from the processed field resistivity data from the three profiles were presented as field data pseudo-sections, theoretical pseudo-section, and 2D resistivity structures. The 2D resistivity structure revealed three structures viz; highly conductive, slightly conductive, and resistive. The resistivity values of these structures ranged from 14.1-99.0 Ω m, 100-848 Ω m, and 1350-90330 Ω m respectively. The highly conductive structures were found in profiles 1 and 3 due to the downward migration of the contaminants from the dead bird disposal pit 1 and the feces disposal site through clayey sand soil. This occurs at the depth range of few meters from the surface to greater than 20 m. The presence of the slightly conductive structure is a result of filtration of the contaminants by the soil materials which increased the resistivity of the soil. The movement of the contaminant through the soil is an indication of the porous and permeable nature of the farmland. The resistive structure is only noticeable in profiles 1 and 2 but very prominent at the depth range of 5 m to more than 20 m and 5 m to 35 m along the profile length. The results of the analysis of the five soil samples from the poultry farmland showed a high value of 0.552 and 3.554 x 10−2cm/s of porosity (Ф) and coefficient of permeability (K) respectively. A strong correlation of R 2 = 0.9878 existed between Ф and K. With these results geo-electrical method had successfully assessed Ф and K of the soil of the poultry farmland.

Intrinsic Parametric Approach to Groundwater Vulnerability Assessment: A Case Study of Ijero Mining Site, Ijero-Ekiti.

The research was conducted to unravel the aquifer protective capacity and groundwater yield of the environment of a mining site at Ijero-Ekiti, Nigeria. The electrical resistivity method was employed and data gotten were used in combining the conventional longitudinal conductance and a new approach that indexes the resistivity and thickness considering some layers which could be protective and have low resistivity like clay material. The area is characterized by the Nigeria Basement Complex consisting of Precambrian rocks, made up of the migmatite gneiss, amphibole schist, quartzite, calc gneiss, schist biotite gneiss, biotite-schist, epidiorite, pegmatite and granite. A total of 9 points were sounded with maximum current electrode separation of 50 – 80 m. The sounding data were interpreted with the aid of partial curve-matching and computer iteration. Result of the interpretation of the geophysical data shows that the area is composed of variable subsurface layering that ranges from three to four layers. Groundwater potential zones were delineated based on the geo-electrical data. The study reveals that VES 1, 3, 4, 5 and 8 have high to medium groundwater potential. However, VES 2, 6 and 9 are characterized by low groundwater potential. The distinct aquifer protective zones identified in the study area using longitudinal conductance and geoelectric layer susceptibility indexing are poor and weak. The study has been able to detect the groundwater yield and the protective capacity of the overburden in the northeastern part of Ijero-Ekiti where a mining site is located using electrical method. Geochemical analysis of water and soil samples from the area is recommended to understand the right treatment required for some of the groundwater sources for drinking.

Study on Deformation and Failure Characteristics of Weak Cemented Roof in Shallow and Extra Thick Coal Seam Mining

Detecting the development height of water flowing fractured zone in the roof of coal seam is of great significance for the roof safety of working face with developed sandstone and thick loose layer. This paper analyzes the influence of the induced polarization effect of electrode on the traditional single-mode parallel electrical method. In order to avoid this interference, the dual-mode parallel electrical method is applied to monitor the roof deformation and failure of a coal mine in Ordos Basin. The monitoring results show that: under the influence of mining, the change of geoelectric field of coal seam roof is dynamic, the apparent resistivity of initial mining fracture is high, the apparent resistivity of surrounding rock water filling mining fracture is low, and the apparent resistivity of fracture water flowing to goaf is high again. According to the characteristics of geoelectric field, the maximum height of water flowing fracture zone is 122 M; The average mining coal thickness of the working face is 11 m, and the fracture / mining thickness ratio is 11.1. The results of plastic zone show that the maximum height of water flowing fractured zone above the working face is 122 m, which is consistent with the test results. The vertical stress response characteristics of roof monitoring points are zonal. Under the influence of mining, the loose layer near the surface above the working face is cracked. The edge type ground fissures exist for a long time, and there are a series of geological problems such as soil erosion, ground subsidence.