Papers by Keyword: Liquid

Abstract: The paper addresses the issues of subjective and instrumental quality assessment of flaw detection materials by Sherwin, Bycotest, Spotcheck, Chemetall and R-test penetrant materials using non-metallic test panels and software code.

Abstract: The processes of pyrolysis and combustion of rubber-based synthetic rubbers were studied. Determined that Teflon (polytetrafluoroethylene) helps reduce the rate of burning rubber in half, from 0.25 mm/s to 0.14 m/s based on a mixture of isoprene and butadiene-styrene rubbers

Abstract: This thesis deals with the testing of our wet scrubber by a laboratory at the Faculty of Chemistry, Brno University of Technology. On this wet scrubber, the CO₂ capture efficiency is tested with a splash liquid consisting of 1 % NaOH. An overview of the system, which could increase the capture efficiency of CO₂ from the gas mixture or other harmful particulates in the air, could be improved after introduction. The thesis also deals with finding methods to better capture efficiency of solid particles and gases on the wet scrubber.

Abstract: The paper considers the mathematical model of liquid motion in straight-line capillaries. The proposed mathematical model shows the liquid motion in slit-like capillaries, with regard to the density, viscosity and surface tension of liquids, the capillary size, and the angle of capillary inclination to the horizontal. The modeling results are proved by full-scale experiments.

Abstract: Modern alternative to chemical methods of wood modification is heat treatment, which allows to increase biological stability, to reduce the hygroscopicity of the material and to improve the appearance of products. One of such technologies is heat treatment in liquids. However, this method is characterized by a considerable duration of the process because of cooling the material directly in the liquid. The aim of this work is to improve the technology of thermal modification of wood in liquids by reducing the duration of cooling phase without additional energy consumption. The results of experimental studies of the proposed technology of heat treatment of wood are presented. The obtained data on changes in wood density show that at increasing the average density of the material, there is a reduction in the density of its central layers that is explained by impregnation of the surface layers of wood with wood agent. It can be stated, basing on the analysis of the depth of impregnation of different wood species, that the rate of flow of impregnating liquid is directly proportional to the temperature of heat treatment, in the same time the depth of penetration of the treatment agent into the lumber depends not on treatability of natural wood but its basic density. Therefore, heat treatment of wood in hydrophobic liquids is more rational to use for hard species with greater density, and consequently, a smaller depth of penetration of the treatment agent, which will reduce the flow rate of hydrophobic liquid when carrying out the process and avoid large losses of material during subsequent mechanical processing.

Abstract: Nondestructive penetrant testing is effective, and in some cases, it is the only possible method of accidents prevention at high-risk sites. But in nowadays liquid-filled discontinuity model has not been adequately studied. Hydrodynamics in the open-end capillaries characterize the flow of liquids using the methods of leak detection. To detect surface discontinuities that are capillary, capillary flaw detection methods are used. Until now, the theoretical relation l = l (t) has not been find out. This relation makes it possible to calculate the absorption kinetics in any capillary at all its stages, which would coincide with experimental data with high accuracy. The studies show that the time of filling the capillaries by liquid is usually higher than the theoretically predicted one. Therefore, revealing the regularities of filling capillaries with liquids to the maximum depth and the duration of filling the capillary with liquid by a given depth is an actual task. The authors suggest a model for determining the velocity of fluid in dead-end and open-end and through capillaries, which take into account the fractal topology of the surface.

Abstract: The construction of an experimental set for measurement of refractive index of liquids using fiber optics has been described in this work. The experimental set is aimed for demonstration in physics high school class. A prototype fabricated in laboratory composes of plastic-clad-plastic (PCP) optical fiber with the length of 50 cm, fiber optic transmitter diode, fiber optic phototransistor detector, and liquid container. The diameter and refractive index of the core of PCP optical fiber were 1 mm and 1.492, respectively. The thickness and refractive index of fiber cladding were 1.2 mm and 1.417, respectively. The fiber cladding surface at the central region was removed approximately 5 cm long to form a sensor area. This sensor area was inserted into a cylindrical glass which acted as the container. One end of the fiber was connected to the transmitter diode with a wavelength of 660 nm, and the other end was connected to the detector. A digital multimeter was used to measure an output voltage from the detector. In this work, the effect of water temperature on its refractive index was determined. The results showed that the water refractive index decreased with increasing water temperature and result in the increase of measured output voltage. Furthermore, it was found that the output voltage measured at different temperatures of water depends linearly on water refractive index.

Abstract: Diffusion phenomena are of great importance in materials processing wherein atomic, molecular or ionic species are distributed within a phase or among different phases. Though the phenomenological equation describing the diffusion phenomena including the bulk flow arising out of diffusion in fluid and the phenomena of Kirkendall shift in substitutional solids are the same, these processes are often treated independently. Some discussion on this aspect is presented in the theoretical aspects of diffusion. Owing to the complexity of atomic interactions, prediction of diffusion coefficients in condensed systems from first principles may not be that reliable; Experimental determination of diffusion coefficients is essential. In the second section, some novel experimental techniques developed recently to measure diffusion coefficients in the solid state as well as liquid systems including those in slags are described. In the last section, two case studies on application of diffusion phenomena in process metallurgy are presented emphasizing the importance of these in metallurgical processing.

Abstract: This paper describes a novel device, a wet cell, used for observation in the wet environment inside the scanning electron microscope (SEM). A Wet cell is composed of three counterparts, which are flow control system, thermal system and Wet cell body. The flow system provides continuous buffer liquid to wet cell and maintains cells living at the vacuum environment. It can control different flowrates and switch to different fluidics. Additionally, the thermal system can control the temperature inside the wet cell and maintain at 37 °C. It also offers preheating thermal module to lower the fluctuated of wet cell inside temperature. The wet cell body contains a silicon nitride film based observation window and provides a wet environment for observation between vacuum and anti-vacuum status. In this paper, we introduce the structure and experimental data of flow control and thermal system in Wet cell to let SEM easily provide lots of live imaging information such as dynamics of nano-materials and biological samples in the liquid state.

Abstract: This paper presents an overview of recent computer simulations of grain boundary (GB)diffusion focusing on atomistic understanding of diffusion mechanisms. At low temperatures when GBstructure is ordered, diffusion is mediated by point defects inducing collective jumps of several atomsforming a chain. At high temperatures when GB structure becomes highly disordered, the diffusionprocess can be analyzed by statistical methods developed earlier for supercooled liquids and glasses.Previous atomistic simulations reported in the literature as well as the new simulations presented in thispaper reveal a close similarity between diffusion mechanisms in GBs and in supercooled liquids. GBdiffusion at high temperatures is dominated by collective displacements of atomic groups (clusters),many of which have one-dimensional geometries similar to strings. The recent progress in this fieldmotivates future extensions of atomistic simulations to diffusion in alloy GBs, particularly in glassformingsystems.