scholarly journals Efficiency of Ni Content in Laterite Nickel Deposits through The Least Square Method Approach on Semivariogram

2021 ◽  
Vol 2123 (1) ◽  
pp. 012015
Author(s):  
F Usman ◽  
G M Tinungki ◽  
E T Herdiani

Abstract Ordinary kriging is one of the geostatistical techniques used for spatial prediction on a spatially distributed random plane. Ordinary kriging is a linear unbiased estimator which is part of a semivariogram system of equations that minimizes errors of variance in estimating mineral resources. The semivariogram model shows optimal results in the estimation using the least square method, the effective minimization method smoothes the data points against the curve on a semivariogram graph, the least square makes the size error efficient in the semivariogram model and has been proven to be effective in reducing errors in the semivariogram model in the case of laterite nickel deposits. at PT. Vale Indonesia Tbk. Thus, conclusively the prediction of unsampled Ni content results is very accurate. This is indicated by the lowest root mean square error (RMSE) in limonite in the exponential model, saprolite in the spherical model, and bedrock in the gaussian model. The greatest value of Ni content in this study was in the saprolite layer.

2011 ◽  
Vol 15 (7) ◽  
pp. 2259-2274 ◽  
Author(s):  
S. Ly ◽  
C. Charles ◽  
A. Degré

Abstract. Spatial interpolation of precipitation data is of great importance for hydrological modelling. Geostatistical methods (kriging) are widely applied in spatial interpolation from point measurement to continuous surfaces. The first step in kriging computation is the semi-variogram modelling which usually used only one variogram model for all-moment data. The objective of this paper was to develop different algorithms of spatial interpolation for daily rainfall on 1 km2 regular grids in the catchment area and to compare the results of geostatistical and deterministic approaches. This study leaned on 30-yr daily rainfall data of 70 raingages in the hilly landscape of the Ourthe and Ambleve catchments in Belgium (2908 km2). This area lies between 35 and 693 m in elevation and consists of river networks, which are tributaries of the Meuse River. For geostatistical algorithms, seven semi-variogram models (logarithmic, power, exponential, Gaussian, rational quadratic, spherical and penta-spherical) were fitted to daily sample semi-variogram on a daily basis. These seven variogram models were also adopted to avoid negative interpolated rainfall. The elevation, extracted from a digital elevation model, was incorporated into multivariate geostatistics. Seven validation raingages and cross validation were used to compare the interpolation performance of these algorithms applied to different densities of raingages. We found that between the seven variogram models used, the Gaussian model was the most frequently best fit. Using seven variogram models can avoid negative daily rainfall in ordinary kriging. The negative estimates of kriging were observed for convective more than stratiform rain. The performance of the different methods varied slightly according to the density of raingages, particularly between 8 and 70 raingages but it was much different for interpolation using 4 raingages. Spatial interpolation with the geostatistical and Inverse Distance Weighting (IDW) algorithms outperformed considerably the interpolation with the Thiessen polygon, commonly used in various hydrological models. Integrating elevation into Kriging with an External Drift (KED) and Ordinary Cokriging (OCK) did not improve the interpolation accuracy for daily rainfall. Ordinary Kriging (ORK) and IDW were considered to be the best methods, as they provided smallest RMSE value for nearly all cases. Care should be taken in applying UNK and KED when interpolating daily rainfall with very few neighbourhood sample points. These recommendations complement the results reported in the literature. ORK, UNK and KED using only spherical model offered a slightly better result whereas OCK using seven variogram models achieved better result.


Entropy ◽  
2019 ◽  
Vol 21 (10) ◽  
pp. 933
Author(s):  
Limin Liu ◽  
Yingying Cui

This paper is devoted to the study of the pricing of European options under a non-Gaussian model. This model follows a non-extensive statistical mechanics which can better describe the fractal characteristics of price movement in the financial market. Moreover, we present a simple but precise least-square method for approximation and obtain a closed-form solution of the price of European options. The advantages of this technique are illustrated by numerical simulation, which shows that the least-squares method is better compared with Borland’s two methods in 2002 and 2004.


2009 ◽  
Vol 46 (8) ◽  
pp. 611-625
Author(s):  
Wenyou Tao ◽  
Yang Gao

Based on the near real-time Global Positioning System (GPS) precise pointing positioning (PPP)-inferred water vapor system recently developed at the University of Calgary, Calgary, Alberta, an Ordinary Kriging procedure has been developed to predict the local and regional precipitable water vapor (PWV) and describe its distribution over Canada using limited available data. The Ordinary Kriging procedure includes five steps: (1) quantifying PWV spatial structure by calculating an experimental semivariogram; (2) fitting semivariogram models (spherical, exponential, and Gaussian) with nonlinear, weighted least squares; (3) determining the best-fitted model with cross-validation analysis; (4) estimating whole PWV maps by Ordinary Kriging interpolation; and (5) outputting kriging standard error maps. The 24 h variogram analysis shows that the correctly calculated experimental semivariogram is essential to the accuracy of the kriged maps, which depends on the configuration of the sites, lag step, and lag tolerance. The optimal lag step and lag tolerance for the current Canadian GPS network configuration are 5° and 2.5°, respectively. Among the three semivariogram models, the spherical model fails in its performance most of the time, and the best hourly fitted semivariogram model is either the exponential (90%) or the Gaussian (10%) model. The Gaussian-model-based Ordinary Kriging process produces more detailed maps. The surface maps of the kriging standard errors indicate that the area between longitudes –125° and –60° and latitudes 44° and 54° has higher accuracy due to higher availability of data.


2013 ◽  
Vol 415 ◽  
pp. 488-493
Author(s):  
Xiu Yan Zhang ◽  
Quan Lin Dong ◽  
Yong Jun Cui

Axial field distribution model of pole piece has a certain theory value in the design of magnetic lenses. In this paper, on the base of analyzing pole piece axial field distribution model which other authors had deduced, using the nonlinear least square method and the curve fitting tool of MATLAB software, the Gaussian model for axial field distribution is obtained. By comparing these models, the Gaussian model has higher precision and also has a certain practical reference value.


2020 ◽  
Vol 13 (4) ◽  
pp. 1819
Author(s):  
Alana Rêgo ◽  
Joel Bezerra ◽  
Jorge Pinto Filho

A diminuição da disponibilidade hídrica vivenciada em regiões semiáridas associada à degradação da qualidade da água justifica a necessidade de ações gerenciais que visem a conservação dos recursos hídricos. Nesse sentido, o presente estudo visa realizar a modelagem espacial da qualidade da água nas comunidades rurais da Chapada do Apodi/RN. Para avaliação desse utilizou-se análise estatística descritiva dos parâmetros físico-químicos e biológicos, mediante análise dos padrões de qualidade da água conforme legislação vigente. Em seguida utilizou-se da correlação linear de Pearson para fins de verificação de dependência entre as variáveis em estudo, e interpolação por krigagem ordinária acompanhada da determinação dos semivariogramas experimentais. constatou-se que os parâmetros pH, turbidez, OD, STD, C. totais e do tipo E. coli, apresentaram resultados desconformes se comparados com a legislação vigente. Por meio da correlação linear de Pearson evidenciou uma moderada correlação entre os STD e temperatura, STD e pH, salinidade e pH, além de OD e turbidez. Além disso, o semivariograma experimental para a temperatura que melhor se ajustou foi o modelo Gaussiano, o pH ajustou-se ao modelo exponencial e as variáveis turbidez, OD e E. coli apresentaram modelo esférico. Já os demais parâmetros, apresentaram efeito pepita puro. Por fim, por meio das cartas temáticas através da interpolação por krigagem ordinária, constatou-se que as maiores concentrações tenderam a ocorrer em localidades com maiores concentrações de comunidades rurais, e comprovar um cenário de alerta na saúde pública e necessidade de monitoramento da qualidade da água. Spatial modeling of water quality in rural communities of Chapada do Apodi – RN A B S T R A C TThe decrease in water availability experienced in semiarid regions associated with water quality degradation justifies the need for management actions aimed at conserving water resources. In this sense, the present study aims to perform spatial modeling of water quality in rural communities of Chapada do Apodi/RN. For the evaluation of this, descriptive statistical analysis of the physicochemical and biological parameters was used, through the analysis of water quality standards according to current legislation. Next, pearson's linear correlation was used for the purpose of verifying dependence between the variables under study, and interpolation by ordinary kriging accompanied by the determination of experimental semivariograms. it was found that the parameters pH, turbidity, OD, STD, C. total and type E. coli, presented results that were inconsistent when compared to the current legislation. Pearson's linear correlation showed a moderate correlation between TDS and temperature, STD and pH, salinity and pH, in addition to OD and turbidity. In addition, the experimental semivariogram for the temperature that best adjusted was the Gaussian model, the pH adjusted to the exponential model and the variables turbidity, OD and E. coli presented spherical model. The other parameters showed a pure nugget effect. Finally, through thematic letters through interpolation by ordinary kriging, it was found that the highest concentrations tended to occur in localities with higher concentrations of rural communities, and to prove a scenario of alert in public health and need to monitor water quality.Keywords: Geostatistics. Groundwater. Ordinary Kriging. Conservation of water resources


1981 ◽  
Vol 20 (06) ◽  
pp. 274-278
Author(s):  
J. Liniecki ◽  
J. Bialobrzeski ◽  
Ewa Mlodkowska ◽  
M. J. Surma

A concept of a kidney uptake coefficient (UC) of 131I-o-hippurate was developed by analogy from the corresponding kidney clearance of blood plasma in the early period after injection of the hippurate. The UC for each kidney was defined as the count-rate over its ROI at a time shorter than the peak in the renoscintigraphic curve divided by the integral of the count-rate curve over the "blood"-ROI. A procedure for normalization of both curves against each other was also developed. The total kidney clearance of the hippurate was determined from the function of plasma activity concentration vs. time after a single injection; the determinations were made at 5, 10, 15, 20, 30, 45, 60, 75 and 90 min after intravenous administration of 131I-o-hippurate and the best-fit curve was obtained by means of the least-square method. When the UC was related to the absolute value of the clearance a positive linear correlation was found (r = 0.922, ρ > 0.99). Using this regression equation the clearance could be estimated in reverse from the uptake coefficient calculated solely on the basis of the renoscintigraphic curves without blood sampling. The errors of the estimate are compatible with the requirement of a fast appraisal of renal function for purposes of clinical diagknosis.


2015 ◽  
Vol 5 (2) ◽  
pp. 1
Author(s):  
Miftahol Arifin

The purpose of this research is to analyze the influence of knowledge management on employee performance, analyze the effect of competence on employee performance, analyze the influence of motivation on employee performance). In this study, samples taken are structural employees PT.centris Kingdom Taxi Yogyakarta. The analysis tool in this study using multiple linear regression with Ordinary Least Square method (OLS). The conclusion of this study showed that the variables of knowledge management has a significant influence on employee performance, competence variables have an influence on employee performance, motivation variables have an influence on employee performance, The analysis showed that the variables of knowledge management, competence, motivation on employee performance.Keywords: knowledge management, competence, motivation, employee performance.


2020 ◽  
Vol 1 (1) ◽  
pp. 128-140 ◽  
Author(s):  
Mohammad Hatami ◽  
◽  
D Jing ◽  

In this study, two-phase asymmetric peristaltic Carreau-Yasuda nanofluid flow in a vertical and tapered wavy channel is demonstrated and the mixed heat transfer analysis is considered for it. For the modeling, two-phase method is considered to be able to study the nanoparticles concentration as a separate phase. Also it is assumed that peristaltic waves travel along X-axis at a constant speed, c. Furthermore, constant temperatures and constant nanoparticle concentrations are considered for both, left and right walls. This study aims at an analytical solution of the problem by means of least square method (LSM) using the Maple 15.0 mathematical software. Numerical outcomes will be compared. Finally, the effects of most important parameters (Weissenberg number, Prandtl number, Brownian motion parameter, thermophoresis parameter, local temperature and nanoparticle Grashof numbers) on the velocities, temperature and nanoparticles concentration functions are presented. As an important outcome, on the left side of the channel, increasing the Grashof numbers leads to a reduction in velocity profiles, while on the right side, it is the other way around.


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