Recognition and classification of carbon stars

A sample of 67 carbon stars is investigated by the method of multidimensional statistical analysis. As a result, three main factors are distinguished: Fl, F2, and F₃. Various relationships between these factors and the spectral subtypes of carbon stars are considered. Carbon stars are clearly differentiated with respect to Fl and F3 and form separate types (R and N) of objects, while the difference with respect to F2 is not significant. A comparison of the factors Fl, F2, and F3 and the two-dimensional C classification shows that Fl correlates with the first temperature parameter of the C classification while F2 and F3 correlate with the second parameter, reflecting the variation of carbon abundance. The error in classifying this sample of carbon stars with respect to the first parameter does not exceed 1.5 spectral subtypes, while with respect to the second it does not exceed 1.8 subtypes.     

Isotherms for the sorption of zinc and copper onto kaolinite: comparison of various error functions

In this research, the equilibrium sorption of Zn(II) and Cu(II) by kaolinite was explained using the Freundlich, Langmuir and Redlich–Peterson isotherms, via both linear and non-linear regression analyses. In the case of non-linear regression method, the best-fitting model was evaluated using six different error functions, namely coefficient of determination (r ²), hybrid fractional error function (HYBRID), Marquardt’s percent standard deviation (MPSD), average relative error (ARE), sum of the errors squared (SSE) and sum of the absolute errors (EABS). The examination of error estimation methods showed that the Langmuir model provides the best fit for the experimental equilibrium data for both linear and non-linear regression analyses. The SSE function was found to be a better option to minimize the error distribution between the experimental equilibrium data and predicted two-parameter isotherms. In the case of three-parameter isotherm, HYBRID was found to be the best error function to minimize the error distribution structure between experimental equilibrium data and theoretical isotherms. Non-linear method was found to be more appropriate method for estimating the isotherm parameters.     

Remediation of colloid-facilitated contaminant transport in saturated porous media treated by nanoparticles

Facilitation of contaminant transport in porous media due to the effect of indigenous colloidal fine materials has been widely observed in laboratory and field studies. It has been explained by the increase in the apparent solubility of low soluble contaminants as a result of their adsorption on the surface of fine particles. Attachment of colloidal fine particles onto the rock surface could be a promising remedy for this challenge. In this experimental study, the effect of five types of metal oxide nanoparticles, γ-Al₂O₃, ZnO, CuO, MgO, and SiO_2, on suspension transport was investigated. In several core flooding tests, different nanofluids were used to saturate the synthetic porous media. Subsequently, after sufficient soaking time, the suspension was injected into the treated porous media. Analysis of the effluent samples’ concentration by Turbidimeter apparatus demonstrated that the presence of nanoparticles on the rock surface resulted in a significant reduction in fine concentrations in the effluent samples compared with non-treated media; ZnO and γ-Al₂O₃ demonstrated the best scenarios among the tests performed in this study. In order to characterize the surface properties of the treated porous media, the zeta potential of the surface was measured. Results showed that the treated porous media acts as a strong adsorbent of fine particles, which are the main carrier of contaminants in porous media. These findings were quantitatively confirmed by calculation of the total energy of interaction between the fine particles and rock surface using the Derjaguin–Landau–Verwey–Overbeek theory.     

Creation of high-resolution climatic grid datasets for the territory of Georgia

Created are the grid datasets of monthly mean and annual mean temperature as well of monthly, seasonal, and annual values of the total precipitation with the resolution of 25 km for the period of 1936–2011. The obtained datasets characterize the real picture of the spatial distribution of temperature and precipitation on the territory of Georgia; therefore, they are used for working out geoinformative maps of temperature and precipitation variations. Revealed are the areas and centers with different intensity of warming and cooling. It is found that the annual temperature and total annual precipitation averaged for the territory do not vary considerably under conditions of the global warming.     

Modelling of Elastic Stress Field of the Earth’s Crust in Central Asia Based on the Orientations of Principal Stress Axes

Izvestiya, Physics of the Solid Earth - In this work, we perform reconstruction of elastic stress fields by employing discrete data on the principal directions of the stress tensor in Central Asia....     

REMOTE SENSING IN THE STATISTICAL CHARACTERIZATION OF ATMOSPHERIC PARAMETERS

An analysis of the statistical characteristics of the optical depth of suspended particulates was made in several parts of the visible spectrum as it is affected by meteorological conditions. The paper tests whether the association of the statistical characteristics of the spectral structure of visible radiation with meteorological parameters is strong enough to serve as part of the explanation for the onset of different states of atmospheric turbidity. Equations are derived that permit estimation of atmospheric optical conditions from meteorological data.     

南阿尔金木纳布拉克地区高压泥质麻粒岩的确定及其地质意义

南阿尔金木纳布拉克地区出露一套典型的高压泥质麻粒岩,其峰期特征矿物组合为Grt+ Ky+ Kfs+Qz+Ilm.根据矿物内部一致性热力学数据和Thermocalc3.33程序计算,确定其峰期变质温压条件为T＞850℃和P＞11kbar.结合岩相学研究和P-T视剖面图计算,可识别出该岩石经历了3个阶段的变质演化,构成了一个早期降温降压,后期近等压降温的顺时针型的退变质P-T演化轨迹.该岩石锆石阴极发光图像显示其内部具有明显的核-边结构,核部为残留的原岩碎屑锆石,边部则表现为面状生长的变质锆石的特征.微区原位LA-ICP-MS微量元素分析和锆石U-Pb定年表明,该岩石原岩的形成时代上限值约为579Ma,变质年龄为486±5Ma.该麻粒岩与南阿尔金淡水泉地区的高压麻粒岩具有相似变质演化轨迹和一致的峰期变质年龄,亦与南阿尔金其它超高压岩石的峰期变质年龄一致,表明它们都是南阿尔金陆壳深俯冲作用引发的高压-超高压变质事件的产物,它们共同构成南阿尔金高压-超高压变质带.同时代的UHP榴辉岩和高压麻粒岩共存的现象,可以很好地利用“俯冲隧道模型”来解释,即可能是由于陆壳在深俯冲过程中不同深度不同热状态下发生拆离作用后折返引起的.另外,该麻粒岩的原岩形成时代(约为579Ma),可能为新元古代晚期,与南阿尔金高压-超高压岩石的原岩形成时代基本一致或稍晚,因此不应再作为岩石地层单元划归为“长城系”,而应归属为南阿尔金高压-超高压变质岩带的一部分.