Structural Exploration of Aeromagnetic Data over Part of Gwagwala­da,Abuja for Potential Mineral Targets Using Derivatives Filters

Aeromagnetic data are consistently used for economic interest targeting and geological mapping.Besides solving problems that are concerned with the basement,the method has become a useful tool in exploring minerals,hydrocarbons occurrence,groundwater investigations,and geothermal potentials.This study analyses aeromagnetic data from the Nigerian Geological Survey Agency acquired at 100 m terrain clearance over a section of Gwagwalada in Abuja.The study area spans longitudes 7.0875°E to 7.1458°E and latitude 8.9625°N to 9.0°N(about 27 km^(2)).After a reduction to the equator(RTE)transformation,the data is downward continued by 50 m.Different filters are applied to outline area of alteration associated to mineral deposit.Regional geologic structures trend NE-SW.The application of vertical derivatives(FVD and SVD)to the RTE grid enhanced shallow structures which trend NE-SW.Horizontal gradients along the X-and Y-directions enhance geological contacts attributable to blind faults.The Tilt derivative(TD)accentuated fault lines which trend NE-SW.

Equidistant combination wavelength screening and step-by-step phase-out method for the near-infrared spectroscopic analysis of serum urea nitrogen

We applied near-infrared(NIR)spectroscopy with chemometrics for the rapid and reagent-fee analysis of serum urea nitrogen(SUN).The modeling is based on the average effect of multiple sample partitions to achieve parameter selection with stability.A multiparameter optimization platform with Norris derivative filter-partial least squares(Norris-PLS)was developed to select the most suitable mode(d=2,s=33,g=15).Using equidistant combination PLS(EC-PLS)with four parameters(initial wavelength I,number of wavelengths N,number of wavelength gaps G and latent variables LV),we performed wavelength screening after eliminating high-absorption wavebands.The optimal EC-PLS parameters were I=1228 nm,N=26,G=16 and LV=12.The root-mean square error(SEP),correlation coefficient(R_(p))for prediction and ratio of performance-to-deviation(RPD)for validation were 1.03 mmol L^(-1),0.992 and 7.6,respectively.We proposed the wavelength step-by-step phase-out PLS(WSP-PLS)to remove redun-dant wavelengths in the top 100 EC-PLS models with improved prediction performance.The combination of 19 wavelengths was identifed as the optimal model for SUN.The SEP,Rp and RPD in validation were 1.01 mmol L^(-1),0.992 and 7.7,respectively.The prediction effect and wavelength complexity were better than those of EC-PIS.Our results showed that NIR spectroscopy combined with the EC-PLS and WSP-PLS methods enabled the high-precision analysis ofSUN.WSP-PLS is a secondary optimization method that can further optimize any wavelength moc odel obtained through other continuous or discrete strategies to establish a simple and better model.

Smooth pulse recovery based on hybrid wavelet threshold denoising and first derivative adaptive smoothing filter

Based on the pulse-shaping unit in the front end of high-power laser facilities,we propose a new hybrid scheme in a closed-loop control system including wavelet threshold denoising for pretreatment and a first derivative adaptive smoothing filter for smooth pulse recovery,so as to effectively restrain the influence of electrical noise and FM-to-AM modulation in the time–power curve,and enhance the calibration accuracy of the pulse shape in the feedback control system.The related simulation and experiment results show that the proposed scheme can obtain a better shaping effect on the high-contrast temporal shape in comparison with the cumulative average algorithm and orthogonal matching pursuit algorithm combined with a traditional smoothing filter.The implementation of the hybrid scheme mechanism increased the signal-to-noise ratio of the laser pulse from about 11 dB to 30 dB,and the filtered pulse is smooth without modulation,with smoothness of about 98.8%.

Design of low noise class D amplifiers using an integrated filter

This paper investigates the noise sources in a single-ended class D amplifier（SECDA） and suggests corresponding ways to lower the noise.The total output noise could be expressed as a function of the gain and noises from different sources.According to the function,the bias voltage（V_B） is a primary noise source,especially for a SECDA with a large gain.A low noise SECDA is obtained by integrating a filter into the SECDA to lower the noise of the V_B.The filter utilizes an active resister and an 80 pF capacitance to get a 3 Hz pole.A noise test and fast Fourier transform analysis show that the noise performance of this SECDA is the same as that of a SECDA with an external filter.

Stability enhancement of wind energy integrated hybrid system with the help of static synchronous compensator and symbiosis organisms search algorithm

Conventional proportional integral derivative(PID)controllers are being used in the industries for control purposes.It is very simple in design and low in cost but it has less capability to minimize the low frequency noises of the systems.Therefore,in this study,a low pass filter has been introduced with the derivative input of the PID controller to minimize the noises and to improve the transient stability of the system.This paper focuses upon the stability improvement of a wind-diesel hybrid power system model(HPSM)using a static synchronous compensator(STATCOM)along with a secondary PID controller with derivative filter(PIDF).Under any load disturbances,the reactive power mismatch occurs in the HPSM that affects the system transient stability.STATCOM with PIDF controller is used to provide reactive power support and to improve stability of the HPSM.The controller parameters are also optimized by using soft computing technique for performance improvement.This paper proposes the effectiveness of symbiosis organisms search algorithm for optimization purpose.Binary coded genetic algorithm and gravitational search algorithm are used for the sake of comparison.

Rapid and simultaneous analysis of multiple wine quality indicators through near-infrared spectroscopy with twice optimization for wavelength model

Alcohol,total sugar,total acid,and total phenol contents are the main indicators of wine quality detection.This study aims to establish simultaneous analysis models for the four indicators through near-infrared(NIR)spectroscopy with wavelength optimization.A Norris derivative filter(NDF)platform with multiparameter optimization was established for spectral pretreatment.The optimal parameters(i.e.,derivative order,number of smoothing points,and number of differential gaps)were(2,9,3)for alcohol,(1,19,5)for total sugar,(1,17,11)for total acid,and(1,1,1)for total phenol.The equidistant combinationpartial least squares(EC-PLS)was used for large-scale wavelength screening.The wavelength step-by-step phaseout PLS(WSP-PLS)and exhaustive methods were used for secondary optimization.The final optimization models for the four indicators included 7,10,15,and 13 wavelengths located in the overtone or combination regions,respectively.In an independent validation,the root mean square errors,correlation coefficient for prediction(i.e.,SEP and RP),and ratio of performance-to-deviation(RPD)were 0.41 v/v,0.947,and 3.2 for alcohol;1.48 g/L,0.992,and 6.8 for total sugar;0.68 g/L,0.981,and5.1 for total acid;and 0.181 g/L,0.948,and 2.9 for total phenol.The results indicate high correlation,low error,and good overall prediction performance.Consequently,the established reagent-free NIR analytical models are important in the rapid and real-time quality detection of the wine fermentation process and finished products.The proposed wavelength models provide a valuable reference for designing small dedicated instruments.