Integrating Core and Aeromagnetic Datasets to Evaluate Mineral Potential of Southern Nupe Basin, Nigeria

Aeromagnetic and core drilled data covering parts of southern Nupe Basin was acquired and interpreted with the view to evaluating the mineral potentials of the area through interpretation of the structural features in the area; determination of the curie isotherm depth; and correlation of aeromagnetic outcomes with the core sample data from the area. Two major regional fault trends were interpreted, trending, Northeast–Southwest (NE–SW) and NNE–SSW with minor northwest–southeast (NW–SE) directions. Two depth sources in the area are delineated namely; zone of shallow seated basement which ranges from 0.42km to 1.5km and zone of deeply seated basement which ranges from 1.91 to 3.50km.Results of qualitative interpretation of the Total magnetic intensity map (TMI) and Residual intensity map reveal that the magnetic intensities ranges from 7500 to 8460 nano-Telsa (nT) and -220 to 240 nT respectively. The depth to the centroid and top of the magnetic caustic bodies ranges from 9.00 to 17.10km and 0.4 to 3.10km respectively. Juxtaposing the topographical and core drilling data reveals that the oolitic iron ore level follows the topographical level which implies that the topography of the area controls the configuration of the iron ore deposit level. All these deduction are made considering the geology of the area.

Gravitational effect of plasma particles on the shadow of Schwarzschild black holes

Considering a Schwarzschild black hole surrounded by a fully ionized hydrogen plasma, we study the effect of the gravitational field of the plasma particles on the shadow. We take a formalism in which this effect is unified with the refractive effect of the plasma medium studied previously, but the two effects are characterized by two independent parameters. For semi-realistic values of parameters, we find their corrections to the shadow radius are both negligible, and the gravitational correction can overtake the refractive correction for active galactic nuclei of masses larger than $$10^9M_{\odot }$$ 10 9 M ⊙ . With unrealistically large values of parameters, we illustrate the two effects on the light trajectories and the intensity map.

Alteration Detection of Multispectral/Hyperspectral Images Using Dual-Path Partial Recurrent Networks

Numerous alteration detection methods are designed based on image transformation algorithms and divergence of bi-temporal images. In the process of feature transformation, pseudo variant information caused by complex external factors will be highlighted. As a result, the error of divergence between the two images will be further enhanced. In this paper, we propose to fuse the variability of Deep Neural Networks’ (DNNs) structure flexibly with various detection algorithms for bi-temporal multispectral/hyperspectral imagery alteration detection. Specifically, the novel Dual-path Partial Recurrent Networks (D-PRNs) was proposed to project more accurate and effective deep features. The Unsupervised Slow Feature Analysis (USFA), Iteratively Reweighted Multivariate Alteration Detection (IRMAD), and Principal Component Analysis (PCA) were then utilized, respectively, with the proposed D-PRNs, to generate two groups of transformed features corresponding to the bi-temporal remote sensing images. We next employed the Chi-square distance to compute the divergence between two groups of transformed features and, thus, obtain the Alteration Intensity Map. Finally, threshold algorithms K-means and Otsu were, respectively, applied to transform the Alteration Intensity Map into Binary Alteration Map. Experiments were conducted on two bi-temporal remote sensing image datasets, and the testing results proved that the proposed alteration detection model using D-PRNs outperformed the state-of-the-art alteration detection model.

Comparison of Direct Intersection and Sonogram Methods for Acoustic Indoor Localization of Persons

We discuss two methods to detect the presence and location of a person in an acoustically small-scale room and compare the performances for a simulated person in distances between 1 and 2 m. The first method is Direct Intersection, which determines a coordinate point based on the intersection of spheroids defined by observed distances of high-intensity reverberations. The second method, Sonogram analysis, overlays all channels’ room impulse responses to generate an intensity map for the observed environment. We demonstrate that the former method has lower computational complexity that almost halves the execution time in the best observed case, but about 7 times slower in the worst case compared to the Sonogram method while using 2.4 times less memory. Both approaches yield similar mean absolute localization errors between 0.3 and 0.9 m. The Direct Intersection method performs more precise in the best case, while the Sonogram method performs more robustly.

2-dimensional modeling of high-resolution aeromagnetic data over Yola arm of the upper Benue trough, Northeastern Nigeria

2-D modeling of high-resolution aeromagnetic data over the area investigated was carried out with the aid of Oasis MontajTM software in order to get the total magnetic intensity map as well as the residual map from where the modeling was carried out. The data was acquired for Nigeria Geological Survey Agency (NGSA) in 2010 by Fugro international of Netherlands. The specifications of the data were terrain clearance of 80 m, flight line spacing of 500 m and a tie line spacing of 5000 m. The area investigated in this work is located between longitude 120 00' - 130 30' E and Latitude 80 00' – 100 00'N. GM-SYS module of the Oasis montaj was used for this research, with depocentres, structural patterns, basement geometry and morphology as well as estimates of the physical character of the cause to an investigated anomaly determined. The models reveal the horst and graben structures of the basement and the various faults that segmented the area into block patterns. The results revealed sediment thickness in the range of 2-5 km for the models which are in agreement with the results obtained by various researchers in the area. Horst and graben were identified in the models which confirmed the rifting nature of the Benue Trough. The authors of this research are of the view that these depocentres, structural patterns and basement geometry may be a promising site for hydrocarbon traps and reservoirs. Keywords: Aeromagnetic Data, GM-SYS, Modeling, Horst, Graben.

Comparison of Direct Intersection and Sonogram Methods for Acoustic Indoor Localization of Persons

We discuss two methods to detect the presence and location of a person in a small-scale room and compare the performances. The first method is Direct Intersection, which determines a coordinate point based on the intersection of spheroids defined by observed distances of high-intensity reverberations. The second method, Sonogram analysis, overlays all channel’s room impulse responses to generate an intensity map for the observed environment. We demonstrate that the former method has lower computation complexity and higher accuracy for small numbers of channels, while the latter performs more robustly.

Spatial Intensity Map of HDEMG Based Classification of Muscle Fatigue

In this, study, we have investigated to identify the muscle fatigue using spatial maps of High-Density Electromyography (HDEMG). The experiment involves subjects performing plantar flexion at 40% maximum voluntary contraction until fatigue. During the experiment, HDEMG signal was recorded from the tibialis anterior muscle. The monopolar and bipolar spatial intensity maps were extracted from the HDEMG signal. The random forest classifier with different tree configurations was tested to distinguish nonfatigue and fatigue condition. The results indicate that selected electrodes from the differential intensity map results in an accuracy of 83.3% with the number of trees set at 17. This method of spatial analysis of HDEMG signals may be extended to assess fatigue in real life scenarios.