Vibration characteristics of rotating functionally graded porous beams reinforced by graphene platelets

This work aims to study the vibration characteristics of the rotating functionally graded porous beam reinforced by graphene platelets. The beam is mounted and rotated around a hub with a constant velocity. The material properties vary along the thickness direction with two types of porosity distributions and two dispersion patterns of graphene platelet. The equations of motion based on the Timoshenko beam theory are obtained and solved using the Chebyshev-Ritz method. The effects of the parameters such as hub radius, rotating speed, weight fraction, porosity distribution, porosity coefficient, and dispersion model are presented. The present method results are also compared with numerical results available in the literature.

COMPACTION OF LINEAR ELASTIC-CREEPING INHOMOGENEOUS SOILS

В данной работе рассмотрен процесс уплотнения линейных упругоползучих неоднородных грунтов. Областью изменения независимых переменных является прямоугольник, образованный прямыми х=±ℓ; y=0; y=h. Уплотнение этого прямоугольника безусловно определяется своей сжимаемостью. Сжимаемость основания зависит как от типа грунта, так и от характера нагрузки. При этом деформация сжатия грунтов в основном происходит вследствие сближения твердых частиц между собой и оценивается изменением коэффициента пористости при изменении сжимающих напряжений в скелете грунта. Определение этой зависимости обычно производится лабораторным путем в компрессионных приборах. In this paper, the process of compaction of linear elastic-creeping inhomogeneous soils is considered. The domain of change of independent variables is a rectangle formed by straight lines x = ±l; y = 0; y = h. the Compaction of this rectangle is unconditionally determined by its compressibility. Compressibility of the base depends on both the type of soil and the nature of the load. In this case, the deformation of soil compression mainly occurs due to the convergence of solid particles with each other and is estimated by changing the porosity coefficient when compressive stresses in the soil skeleton change. The determination of this dependence is usually made by laboratory means in compression devices.

Eyes in cheese: reasons for formation and methods of assessment

The results of scientific research of the process of eyes formation in cheeses depending on the molding method and modes of pressing the cheese mass; the type of gassing microorganisms that make up the starter culture; rheological properties of curd; the presence in the cheese mass of “germs” — the centers of the formation of eyes — are considered. It is noted that the most studied in terms of the formation of the pattern are large cheeses of the Emmental or Swiss type with eyes up to 3 cm in diameter, which can be easily estimated by calculating their quantity and volume. For this, there are methods for visualizing eyes in the volume of cheese: X-ray, computed and magnetic resonance imaging, ultrasound and acoustic sounding. The least studied is the process of pattern formation in cheeses like Tilsiter and Russian, molded in bulk, with a large number of irregular, angular eyes. In connection with the observed tendency to the loss of the distinctive features of this type of cheese (rare, insufficiently pronounced eyes), great importance is attached to objective methods for assessing the pattern in these cheeses as one of the most important indicators of the product quality. Since computed tomography, X-ray and magnetic resonance imaging are methods that require expensive equipment, the need for a simpler procedure, suitable for production laboratories of cheesemaking enterprises, is justified for use in routine examinations. Based on the assumption that cheeses with a frequent pattern of angular, irregular shape can be considered as porous bodies, an assumption was made about the advisability of developing a method for measuring the porosity coefficient, which could supplement the organoleptic assessment of the pattern with an objective indicator that would allow the rejection of cheeses on this basis.

Specific features of the probability petrophysical estimation of rock formations using the approaches of the concept of porous space connectedness

Background. The technology of probability petrophysical estimation of parameters using layer-bylayer interpretation of well logging data is present in this paper. Specific features of the technology is to using both the vertical and horizontal processing. Aim. The aim of the technology is the possibility of its adaptation when interpreting well logging data using the approaches of the concept of pore space connectedness, which reduce the variability of estimates of productive thicknesses of reservoirs in comparison with traditional approaches to calculating geological reserves using fixed cutoff porosity coefficient. Materials and methods. The paper discusses the main features of modeling the uncertainties of the input parameters and ways of representing them in the form of various distributions with a description of a generalized algorithm for the probabilistic assessment of geological reserves. The distributions of the reservoir area, oil density and conversion factor, the basic version of the results of the reservoir logging data interpretation in the form of a table continuous in depth with readings from the logging methods curves in intervals homogeneous in lithology are use as input parameters when executing the algorithm. In addition, distributions reflecting variations in the uncertainties of geophysical parameters, constants of petrophysical models, boundary cutoff s for identifying reservoirs and assessing their saturation nature are used to the input of the algorithm. Results. An algorithm for probabilistic petrophysical assessment has been developed taking into account the use of petrophysical modeling within the framework of the concept of pore space connectivity and the layer-by-layer mode of interpretation of well logging data. It is shown that additional petrotyping, which makes it possible to clarify the parameter of pore space connectivity, reduces the error of the resulting estimates, which can reduce the risk of making ineffective decisions. Conclusions. It is show that additional petrotyping, which makes it possible to clarify the parameter of pore space connectedness, reduces the error of the resulting estimates, which can reduce the risk of making ineffective decisions.

Free vibration analysis of porous beams with gradually varying mechanical properties

This work is aimed to present analysis on free vibration behavior of porous beams with gradually varying mechanical properties based on a robust finite beam element. The governing equations are developed using a mixed variational formulation considering high-order displacement distribution. A new parabolic distribution of the transverse shear strains is introduced and the zero condition of the shear stresses at the upper and bottom surfaces of the beam is satisfied. The porosity can be spread into the beam with evenly and unevenly distributions. According to a modified power function, the material properties are varying along the thickness direction of the FGM porous beam. The presented results show the effect of gradient index, porosity coefficient and forms, boundary conditions, and geometrical parameters on the vibration of FGM beams. It is found that porous beams can be useful as a passive method for control of vibration for structural components.

A comprehensive analysis of conditions and features of oil-and-gas content within the Akhlovskaya structural zone (the North Caucasus)

At the present stage, the development of the oil industry of the Russian Federation is impossible without replenishing the resource base, and therefore an urgent task is to analyze and assess the conditions and characteristics of oil-andgas content in unexplored regions.Purpose of the study is an analysis and an assessment of reservoir properties of rocks of the Aptian horizon Р1+2- К2 within the Akhlovskaya structure.We analyzed the graphs of the distribution of indicators in wells R-212 and R-213 in the Akhlovsky area and concluded that the reservoir is heterogeneous, and there are interlayers of mudstones with other reservoir properties and geophysical characteristics. The following pairs of parameters (porosity coefficient and oil-saturated thickness of rocks, rock resistivity and porosity coefficient, rock resistivity and oil-saturated thickness of rocks) have a significant positive correlation. Having studied the distribution of indicators in the Akhlovsky area for wells R-212 and R-213 along one horizon, we concluded that these indicators differ very slightly, which indicates the homogeneity of the reservoir properties. Qualitative indicators Qualitative indicators don't change. Thus, we can expect similar indicators within the entire area of the explored layer Р1+2- К2 in the territory of the Akhlovsky area.

Natural Frequencies of FG Plates with Two New Distribution of Porosity

The functionally graded plates (FGP) with two new porosity distributions are examined in this paper. In this work the plate is modeled using the higher-order shear deformation plate principle. The shear correction variables are neglected. To evaluate the equations of motion, the Hamilton method will be used herein. Therefore, the free vibration analysis of FG plate is developed in this work. For porous smart plates with simply-supported sides, natural frequencies are obtained and verified with the established findings in the literature. The impact of the porosity coefficient on the normal frequencies of the plate for various thickness ratios, geometric ratios, and material properties was investigated in a thorough numerical analysis.

Analysis of geological-geophysical materials and qualitative assessment of the oil and gas perspectives of the Yuzhno-Kharbizhinsky area (Northern Caucasus)

На современном этапе развитие нефтяной промышленности Российской Федерации невозможно без пополнения ресурсной базы и поэтому актуальной задачей является поиск новых методик оценки и анализа нефтегазоносности перспективных участков. Цель исследований: анализ емкостно-фильтрационных свойств пород коллекторов прикамского горизонта в пределах Южно-Харбижинского участка, с целью прогноза емкостно-фильтрационных параметров на участке Восточный. Методика исследований. Для выполнения анализа емкостно-фильтрационных и геолого-геофизических параметров пород коллекторов кумской свиты Южно-Харбижинского участка, были построены графики изменчивости емкостно-фильтрационных и геолого-геофизических параметров и проведен их корреляционный анализ. Для этого были использованы данные ГИС и данные лабораторных исследований коллекторов, полученные при бурении скважины №88-РД. Оценка коэффициента пористости, объемной плотности, минералогической плотности и плотности насыщенности пород определена на стадии оценки месторождений по методикам А.М. Нечая и Б.Ю. Вендельштейна, Н.В. Манчевой, базирующимся на комплексной интерпретации БК (БКЗ) – НГК и БК (БКЗ) – НГК – ПС. Результаты исследований. Значимой положительной корреляционной связью обладают следующие пары параметров: коэффициент пористости и удельное сопротивление пород, коэффициент пористости и относительное сопротивление пород, коэффициент пористости и объемная плотность, коэффициент пористости и плотность минералогическая, коэффициент пористости и плотность насыщенных пород, удельное сопротивление пород и относительное сопротивление пород, удельное сопротивление пород и объемная плотность, удельное сопротивление пород и плотность минералогическая, удельное сопротивление пород и плотность насыщенных пород, относительное сопротивление пород и объемная плотность, относительное сопротивление пород и плотность минералогическая, относительное сопротивление пород и плотность насыщенных пород, объемная плотность и плотность минералогическая, объемная плотность и плотность насыщенных пород, плотность минералогическая и плотность насыщенных пород. Наблюдается зависимость пористости от сопротивления, что указывает на наличие в породах коллектора углеводородов, т.е. с увеличением пористости увеличивается сопротивление, что также наблюдается на графиках.Изучив распределение показателей на Южно-Харбижинском участке по одному горизонту можно сделать вывод, что эти показатели различаются очень слабо, что свидетельствует об однородности свойств пласта. Качественные показатели остаются без изменения. На Восточном участке можно ожидать схожие показатели. Наличие промышленных скоплений углеводородного сырья оценивается как весьма вероятное At the present stage, the development of the oil industry of the Russian Federation is impossible without replenishing the resource base, and therefore an urgent task is to search for new methods for assessing and analyzing the oil and gas content of promising areas. Aim. Analysis of the reservoir-filtration properties of reservoir rocks of the Kama horizon within the Yuzhno-Kharbizhinsky area, in order to predict the reservoir-filtration parameters for the Vostochny area. Methods. To analyze the reservoir-filtration and geological-geophysical parameters of the reservoir rocks of the Kuma suite of the Yuzhno-Kharbizhinsky area, graphs of the variability of the reservoir-filtration and geological-geophysical parameters were constructed and their correlation analysis was carried out. For this, well logging data and data from laboratory studies of reservoirs obtained during drilling of well No. 88-RD were used. The estimation of the porosity coefficient, bulk density, mineralogical density and saturation density of rocks were determined at the stage of assessing deposits according to the methods of A.M. Nechaya and B.Yu. Wendelstein, N.V. Mancheva, based on a comprehensive interpretation of BK (BKZ) - NGK and BK (BKZ) - NGK - PS. Results. The following pairs of parameters have a significant positive correlation: porosity coefficient and resistivity of rocks, porosity coefficient and relative resistivity of rocks, porosity coefficient and bulk density, porosity coefficient and mineralogical density, porosity coefficient and density of saturated rocks, rock resistivity and relative rock resistance, rock resistivity and bulk density, rock resistivity and mineralogical density, rock resistivity and saturated rock density, rock relative resistivity and bulk density, rock relative resistivity and mineralogical density, rock relative resistivity and saturated rock density, bulk density and mineralogical density, bulk density and density of saturated rocks, mineralogical density and density of saturated rocks.A dependence of porosity on resistance is observed, which indicates the presence of hydrocarbons in the reservoir rocks, i.e. with an increase in porosity, resistance increases, which is also observed in the graphs.Having studied the distribution of indicators in the Yuzhno-Kharbizhinsky area along one horizon, it can be concluded that these indicators differ very slightly, which indicates the homogeneity of the reservoir properties. Qualitative indicators remain unchanged. Similar performance can be expected in the Eastern section. The presence of industrial accumulations of hydrocarbon raw materials is assessed as highly probable

Buckling and Postbuckling of Plates Made of FG-GPL-Reinforced Porous Nanocomposite with Various Shapes and Boundary Conditions

Within the framework of a variational mixed formation and higher-order shear deformation theory (HSDT), a numerical approach is developed in this research to investigate the buckling and post buckling behaviors of variously-shaped plates made of functionally graded graphene platelet-reinforced composites (FG-GPLRCs) taking the effect of porosity into account. By the proposed approach, which can be named as VDQ-FEM, thick and moderately thick plate-type structures with different shapes (e.g. rectangular, skew, or quadrilateral) with arbitrary-shaped cutout (e.g. circular or rectangular) can be studied. Various types for porosity distribution scheme and GPL dispersion pattern including uniform and different functionally graded patterns are considered along the thickness of plate. In the computation of material properties, the closed-cell Gaussian Random field scheme and Halpin–Tsai micromechanical model are utilized. One of the key novelties of proposed approach is developing an efficient way according to the mixed formulation to accommodate the continuity of first-order derivatives on the common boundaries of elements for the used HSDT model. Several numerical examples are given to analyze the influences of porosity coefficient/distribution pattern, GPL weight fraction/dispersion pattern, cutout and boundary conditions on the buckling and postbuckling characteristics of FG-GPLR porous composite plates.

Filter leaching of salt soils of automobile roads

Globally, in arid regions, due to the irrational use of water resources for irrigating plants, salinization of soils occurs, which causes significant damage to the country's economy. In particular, recently in some regions of Uzbekistan, there has been a rise in groundwater and flooding of territories. In these areas, where the soil bases of highways contain such readily soluble salts as: NaCL, Na2SO4·10H2O, MgSO4·7H2O, MgCL2·6H2O, CaCL2·6H2O, NaHCO3, Na2CO3·10H2O, CaCO3 and CaSO4·2H2O, additional suffusion precipitation is often observed which lead to deformations of road surfaces. Additional precipitation is due to the dissolution of salt crystals upon ingress of moisture during filtration leaching. Filtration leaching of soils was carried out in the F-1M device according to the upward flow pattern. To determine the amount of leached salts during the experiment, the infiltrate was taken, its volume and mineralization were recorded. At the end of the tests, the soil was tested according to the general scheme. To assess the influence of the leaching process on the strength indices of the studied soils by the methods of consolidated and fast shear, tests of pre-leached samples were performed. When testing soils, samples were cut, pre-compacted with the same specified load, and leached for a month. In laboratory conditions, the deformation modulus was determined by performing compression experiments. In connection with a sharp change in the modulus of deformation of soils during moistening, the tests were carried out at two values of humidity: at natural and after water saturation without the possibility of swelling. The study results show that the deformation modulus of water-saturated loams satisfactorily correlates with the value of the initial porosity coefficient and decreases as a result of water saturation and leaching. The degree of decrease depends on the value of the initial deformation modulus: the higher it is, the more significant its change. The value of the coefficient of weakening of the soil structure depends on the effective average pressure. The criterion for the permissible salt content in the base of the roadbed of highways should be taken not only the value of the degree of salinity but also the change in the indicators of the mechanical properties of soils used in the design of the construction of the roadway during soaking and leaching.