Approximate determination of the plasma potential spatial distribution in the isolated dust particle vicinity

In this paper, results of two numerical models are compared. The main purpose of these models is to determine the self-consistent spatial distributions of plasma (electric potential and space charge) near isolated spherical dust particles. In the first model, the spatial distribution of the self-consistent plasma potential is determined by expanding the plasma space charge spatial distribution in Legendre polynomials; in the second model, it is determined by direct numerical integration of the Poisson equation solution. The results show that the dependences of the system main parameters (wake magnitude and position, dipole moment of the ion cloud) coincide for small values of the external electrostatic field. With an increase in the external field strength, the dependences for two models cease to coincide, which is due to the inapplicability of Legendre polynomial decomposition in the case of strong anisotropy.

Rock Characterization Through Physical Properties and Their Relationship to Simple Compressive

This work proposes a simple methodology and practical application in the field for the approximate determination of the Unconfined Compressive Strength (UCS) in rocks, property or characteristic that is important in mining, since through it analyzes are carried out to the assessment of security and stability factors and/or possible fortification systems in the works or mining structures, in addition to the characterization of the UCS is also influential in the use of explosives for the exploitation or extraction of materials from a quarry or mine. This estimate is proposed based on the determination of the following three properties of the rock, which in this investigation we call density, porosity and absorption ‘in mine’. These physical properties can be obtained in a simple, but methodical way and in this work, tests have been carried out on the same material or rock from the Cojitambo area, Cañar province (Ecuador) and on the basis of 60 samples or test tubes. The results obtained allow a correlation between the properties described above and the UCS, in addition to a calculation methodology for the proposed objective. Keywords: compression, rock, density, porosity, absorption, fortification. Resumen En este trabajo se propone una metodología sencilla y de aplicación práctica en campo para la determinación aproximada de la Resistencia a la Compresión Simple (RCS) en rocas, propiedad o característica que es importante en minería, ya que mediante la misma, se ejecutan análisis para la valoración de factores de seguridad y estabilidad y/o posibles sistemas de fortificación en las obras o estructuras mineras, a más de que la caracterización de la RCS es también influyente en el uso de explosivos para la explotación o extracción de materiales de una cantera o mina. Esta estimación se la propone en base a la determinación de las siguientes tres propiedades de la roca, que en esta investigación las denominamos densidad, porosidad y absorción ‘en mina’. Estas propiedades físicas se las puede obtener de una forma simple, pero metódica y en este trabajo se han ejecutado ensayos sobre un mismo material o roca proveniente de la zona de Cojitambo, provincia del Cañar (Ecuador) y sobre una base de 60 muestras o probetas. Los resultados obtenidos permiten una correlación entre las propiedades antes descritas y la RCS, a más que se ha estructurado una metodología de cálculo para el objetivo planteado. Palabras Clave: compresión, roca, densidad, porosidad, absorción, fortificación.

Material Characteristics Evaluation for DC04-Welded Tube Hydroforming

Tube hydroforming (THF) technology is widely applied, especially in the automotive and aircraft industries. Material characteristics of tubular workpieces should be evaluated in terms of bending and THF processes. A mathematical model, which combines the assumption of elliptical contour of a bulged wall and the prediction equation of wall thickness, is provided to analyze the THF process and to obtain the strain-stress relationship of tubes. Material characteristics of a DC04-welded tube is obtained by using a self-designed THF test machine. Considering the effects of pre-work hardening, we discuss the material strain-stress relationships of the tube and original sheet blank. An approximate determination method is proposed to obtain the stress-strain curve of the tube by using the curve of the original sheet blank and the hardness of the tube and sheet blank. A suitable constitutive equation with pre-work hardening is applied to the DC04-welded tubes through simulation and experimental methods.

Caracterización de la roca mediante propiedades físicas y su relación con la resistencia a la compresión simple

En este trabajo se propone una metodología sencilla y de aplicación práctica en campo para la determinación aproximada de la Resistencia a la Compresión Simple (RCS) en rocas, propiedad o característica que es importante en minería, ya que mediante la misma, se ejecutan análisis para la valoración de factores de seguridad y estabilidad y/o posibles sistemas de fortificación en las obras o estructuras mineras, a más de que la caracterización de la RCS es también influyente en el uso de explosivos para la explotación o extracción de materiales de una cantera o mina. Esta estimación se la propone en base a la determinación de las siguientes tres propiedades de la roca, que en esta investigación las denominamos densidad, porosidad y absorción “en mina”. Estas propiedades físicas se las puede obtener de una forma simple, pero metódica y en este trabajo se han ejecutado ensayos sobre un mismo material o roca proveniente de la zona de Cojitambo, provincia del Cañar (Ecuador) y sobre una base de 60 muestras o probetas. Los resultados obtenidos permiten una correlación entre las propiedades antes descritas y la RCS, a más que se ha estructurado una metodología de cálculo para el objetivo planteado. This work proposes a simple methodology and practical application in the field for the approximate determination of the Unconfined Compressive Strength (UCS) in rocks, property or characteristic that is important in mining, since through it analyzes are carried out to the assessment of security and stability factors and/or possible fortification systems in the works or mining structures, in addition to the characterization of the UCS is also influential in the use of explosives for the exploitation or extraction of materials from a quarry or mine. This estimate is proposed based on the determination of the following three properties of the rock, which in this investigation we call density, porosity and absorption “in mine”. These physical properties can be obtained in a simple, but methodical way and in this work, tests have been carried out on the same material or rock from the Cojitambo area, Cañar province (Ecuador) and on the basis of 60 samples or test tubes. The results obtained allow a correlation between the properties described above and the UCS, in addition to a calculation methodology for the proposed objective.

Determinação aproximada de chuvas intensas no leste do paraná através da estatística e da álgebra pseudo real / Approximate determination of heavy rain in east paraná through statistics and pseudo real algebra

Este artigo foi elaborado para se mostrar como se pode utilizar a álgebra pseudo-real em correlações usando dados de precipitações intensas de localidades da região leste do Estado do Paraná, de forma a se obter equações de chuvas intensas aproximadas para uso em engenharia de recursos hídricos e aqui vamos analisar uma equação aproximada geral de chuvas intensas para esta região com dados de chuvas intensas obtidas no livro Chuvas Intensas no Brasil correlacionando-as através do uso da estatística pseudo real com as latitudes, as longitudes e as precipitações médias anuais obtidas pela internet.

Multi-stage parallel model in determining the quality of structural timber by the penetration method

Multi-stage parallel model in determining the quality of structural timber by the penetration method. Various devices are used in situ to diagnose the quality of structural timber. A semi-destructive method is used for the approximate determination of wood density. The Pilodyn 6J uses a depth of cut that correlates with wood density. The experiments were performed on spruce wood (Picea excelsa, Karst. L.). Boards 40 × 200 × 2500 mm3, were tested, n = 5 pcs. The density of wood was determined by the gravimetric method according to EN 408 (2013). The penetration depth (hp), number and width of annual rings (RoG) were determined on the boards. Based on the density of the wood, the quality of the structural timber was specified by strength classes according to EN 338 (2016). The dependences between the measured characteristics were expressed in a model with a multi-stage parallel scale (penetration depth ~ number of annual rings  rate of growth  strength class and density wood). It is possible to predict visual strength class of board and indicative density of wood (EN 338) by the proposed model in situ. Methods of model are easy to use, reliable and economically undemanding.

Thermal Conducting Properties of Metal-fluoroplastic Material Determined by Tribological Method

The work is devoted to considering the possibility of using the Fourier law and the data of tribological tests for the approximate determination of the thermophysical characteristics of the sheet metal-fluoroplastic material on a steel substrate. The thermal conductivity coefficient of two different fluoroplastic materials was determined by tribological method using the temperature difference in the friction zone. It was shown that friction conditions change from viscoelastic to plastic

APPROXIMATE DETERMINATION OF GEOMETRIC PARAMETERS OF THE SAG FOLLOWING THE EMBEDDING OF A PARABOLOID INDENTER INTO A HALF-SPACE

The problem of the indenter embedding into a half-space is formulated and solved. A concept of the elastic contact is used, which implies the uniformity of the stress-strain state in a surface layer. The process of the surface layer formation after mechanical treatment is studied. Based on the general theory of indenter penetration into a half-space, numerical and analytical solutions, determining the length and depth of penetration of a paraboloid into elastoplastic space, are obtained. According to the theory of indentation, the problem is reduced to the use of the method of approximate determination of geometric parameters of a bead, when a paraboloid is being embedded into elastoplastic space. An exact solution to the formulated problem allows one to obtain analytical dependences for calculating the velocities and to study the stress-strain state of the material in the half-space surface layer during the processing. The reliability of the obtained analytical solution is confirmed by numerical calculations without introducing additional hypotheses. Based on the analytical solution, the geometric parameters of the influx from the penetration depth are determined. Calculations can be performed at any embedding depth. Sag formation during the indenter embedding by 18 mm into plasticine specimens is considered as an example. It is shown that the rigid zone is insignificant or absent.