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Online since: June 2008
Authors: Pierre Fauchais, Ghislain Montavon
., nano-sized particles, which could permit to form finely grained coatings.
Jodoin [16] has shown that the design of the Mach number of an air nozzle should be limited to 1.5 and above to avoid too high temperature.
To reduce the intensity of this bow shock, the Mach number must be reduced [16].
After a heat treatment above the crystallization temperature (568°C which is less than half melting temperature), the structure of the coatings is devitrified into a multiphase nano-composite microstructure with 75 to 125 nm grains containing a distribution of 20 nm second-phase grain-boundary precipitates [276].
Recently, a grain-growth inhibitor was developed to prevent WC dissolution in the binder, not only maintaining very small grains, but also maintaining their original shape; its drawback is that it decreases the cohesion between WC and binder [310].
Jodoin [16] has shown that the design of the Mach number of an air nozzle should be limited to 1.5 and above to avoid too high temperature.
To reduce the intensity of this bow shock, the Mach number must be reduced [16].
After a heat treatment above the crystallization temperature (568°C which is less than half melting temperature), the structure of the coatings is devitrified into a multiphase nano-composite microstructure with 75 to 125 nm grains containing a distribution of 20 nm second-phase grain-boundary precipitates [276].
Recently, a grain-growth inhibitor was developed to prevent WC dissolution in the binder, not only maintaining very small grains, but also maintaining their original shape; its drawback is that it decreases the cohesion between WC and binder [310].
Online since: July 2007
Authors: Marion Merklein, Manfred Geiger
The decision which kind of temperature assistance is the
most useful in order to improve the formability of the material depends on a hugh number of
process influencing parameters, like e.g. the material itself, the geometry of the component, the
number of forming operations etc..
As a consequence the mass transportation started and the number of traveling persons was increasing from one decade to another.
On the other there is also the idea of integration: today a lot of components, produced in aluminium, are an assembly of a number of single parts.
Taking these investigations into account, the conclusion is that a austenitization temperature between 860 °C and 950 °C with a minimum heat treatment time of 6 to 3 min is necessary, in order to guarantee a complete, homogeneous austenitization of the grain structure.
The reasons are the necessity of thermo-mechanical coupled calculation and the increasing number of boundary conditions and input data.
As a consequence the mass transportation started and the number of traveling persons was increasing from one decade to another.
On the other there is also the idea of integration: today a lot of components, produced in aluminium, are an assembly of a number of single parts.
Taking these investigations into account, the conclusion is that a austenitization temperature between 860 °C and 950 °C with a minimum heat treatment time of 6 to 3 min is necessary, in order to guarantee a complete, homogeneous austenitization of the grain structure.
The reasons are the necessity of thermo-mechanical coupled calculation and the increasing number of boundary conditions and input data.
Online since: May 2011
Authors: Hui Ni Wang, Wan Kui Ni, Gao Yang Liu
Hounsfield of England, one of the inventors of CT unit, gives the concept of CT number.
The unit of CT number is referred to as HU (Hounsfield Unit), 1000 is the scaling factor of HU.
In terms of this definition, the CT number of air is – 1000(HU), and the CT number of pure water is 0(HU).
The CT number of a material reflects its essence density, i.e., the higher the CT number is, the greater the density is.
The CT images present the tendency of loess grains from single particles to particles aggregates, and the porosity reduces obviously and brightness increases.
The unit of CT number is referred to as HU (Hounsfield Unit), 1000 is the scaling factor of HU.
In terms of this definition, the CT number of air is – 1000(HU), and the CT number of pure water is 0(HU).
The CT number of a material reflects its essence density, i.e., the higher the CT number is, the greater the density is.
The CT images present the tendency of loess grains from single particles to particles aggregates, and the porosity reduces obviously and brightness increases.
Online since: February 2014
Authors: Yao Xuan Zhang, Teng Chen, Hou He Chen
However, fluidized-bed drying of RDX is liable to generate a large number of RDX dust, posing some difficulty in subsequent dust recovery, dust handling and air exhaustion.
MRpre,i is the ith predicted moisture ratio, N is the number of observations, n the number of constants in the regression model.
The solution of Fickian equation in such conditions for different geometries has been presented by Crank [26] in Eq. (9): (9) where,is the half thickness of t the thickness of the RDX layer for drying from one side, and n = 1, 2, 3 . . . the number of terms taken into consideration.
Stochastic modelling of grain drying: Part 2.
Grain drying theory I.
MRpre,i is the ith predicted moisture ratio, N is the number of observations, n the number of constants in the regression model.
The solution of Fickian equation in such conditions for different geometries has been presented by Crank [26] in Eq. (9): (9) where,is the half thickness of t the thickness of the RDX layer for drying from one side, and n = 1, 2, 3 . . . the number of terms taken into consideration.
Stochastic modelling of grain drying: Part 2.
Grain drying theory I.
Online since: April 2005
Authors: Sumit Chakraborty
Measurement of a number of
relevant diffusion coefficients in minerals in recent years is improving the quantification of this
aspect (e.g. [13-19]).
The as deposited amorphous thin films can be crystallized to produce interesting geometries on the nanoscale and several aspects of diffusion behaviour (e.g. grain boundary diffusion, surface diffusion, diffusion across heterogeneous couples) can be studied using these thin film coated crystals.
To simplify numerical modeling of mass transfer under these conditions, a number of concepts have been borrowed and modified from the materials sciences.
In the second study, we extend this to a system consisting of any number of phases and components and handle the problem numerically.
Areas where Research in other areas may benefit Geosciences: There are a number of areas where the Earth and Planetary Sciences stand to benefit by importing expertise from other areas.
The as deposited amorphous thin films can be crystallized to produce interesting geometries on the nanoscale and several aspects of diffusion behaviour (e.g. grain boundary diffusion, surface diffusion, diffusion across heterogeneous couples) can be studied using these thin film coated crystals.
To simplify numerical modeling of mass transfer under these conditions, a number of concepts have been borrowed and modified from the materials sciences.
In the second study, we extend this to a system consisting of any number of phases and components and handle the problem numerically.
Areas where Research in other areas may benefit Geosciences: There are a number of areas where the Earth and Planetary Sciences stand to benefit by importing expertise from other areas.
Online since: March 2020
Authors: Oluwole Daniel Makinde, Gurrampati Venkata Ramana Reddy, Kolli Vijaya
The Skin-friction, Nusselt number and Sherwood number are discussed in detail.
Introduction Mass transfer and Coupled heat effectshave tremendous engineering applicationssuch as grain storage installations, chemical catalytic reactors, filtrationprocessesand diffusion of medicine in blood veinsthrough the air contained in fibrous insulation [1].
The effect of Schmidt number (Sc), magnetic parameter (M), Grashof number and modified Grashof nuber (Gr, Gm) on Skin-friction, Nusselt number and Sherwood number.
The Schmidt number (Sc), magnetic parameter (M), Grashof number and modified Grashof number (Gr,Gm) are increases then Skin-friction, Nusselt number and Sherwood number increases. when Casson parameter increases, the Skin-friction, Nusselt number and Sherwood number decreases.
The remaining parameters like radiation, Prandtl number, chemical reaction parameter, Soret number and biot number are increases then Skin-friction, Nusselt number and Sherwood number are also increases.
Introduction Mass transfer and Coupled heat effectshave tremendous engineering applicationssuch as grain storage installations, chemical catalytic reactors, filtrationprocessesand diffusion of medicine in blood veinsthrough the air contained in fibrous insulation [1].
The effect of Schmidt number (Sc), magnetic parameter (M), Grashof number and modified Grashof nuber (Gr, Gm) on Skin-friction, Nusselt number and Sherwood number.
The Schmidt number (Sc), magnetic parameter (M), Grashof number and modified Grashof number (Gr,Gm) are increases then Skin-friction, Nusselt number and Sherwood number increases. when Casson parameter increases, the Skin-friction, Nusselt number and Sherwood number decreases.
The remaining parameters like radiation, Prandtl number, chemical reaction parameter, Soret number and biot number are increases then Skin-friction, Nusselt number and Sherwood number are also increases.
Online since: June 2018
Authors: Dmytro Babets
Introduction
An important and one of the most challenging tasks in rock engineering and design is converting the considerable number of parameters estimated by field mapping, core drilling and laboratory testing into the underground structure model.
A substantial number of theoretical studies based on statistical analysis of rock strength were conducted since 1960th by Volkov (1960), Koyfman (1963), Sedrakian (1968), Rats (1968), Brady (1970) and others [3].
It is supposed that strength of such elements is close to zero and their number (nt) in a random sample depends on the distance between joints in the rock mass.
Experimental Studies The substantial number of laboratory tests was carried out by Author in National Mining University (Ukraine), AGH Krakow (Poland) and SIU Carbondale (USA).
A substantial effect of mineralogical composition and petrographic features (grain size, grain bindings, weathering, micro-cracking) on the results of compressive strength test is confirmed.
A substantial number of theoretical studies based on statistical analysis of rock strength were conducted since 1960th by Volkov (1960), Koyfman (1963), Sedrakian (1968), Rats (1968), Brady (1970) and others [3].
It is supposed that strength of such elements is close to zero and their number (nt) in a random sample depends on the distance between joints in the rock mass.
Experimental Studies The substantial number of laboratory tests was carried out by Author in National Mining University (Ukraine), AGH Krakow (Poland) and SIU Carbondale (USA).
A substantial effect of mineralogical composition and petrographic features (grain size, grain bindings, weathering, micro-cracking) on the results of compressive strength test is confirmed.
Online since: April 2021
Authors: Abdelkader El Kissani, Hind El Aakib, Abderrahmane Abbassi, Abdelfattah Narjis, Amane Oueriagli, Abdelkader Outzourhit, Lahcen Nkhaili
Deposition of ZnO buffer layer on ITO substrates by electrodeposition
For the electrodeposition of the nucleation layer, an electrolyte containing 5×10-3 Mol.L-1 of Zinc chloride (ZnCl2, 98%, CAS number 7646-85-7) and 0.1 Mol.L-1 of Potassium chloride (KCl, CAS Number: 7447-40-7 ) dissolved in ultra-pure water was used.
The increase in the density of nanowires and the variation in their diameters seem to be due to the small grain size of the ZnO buffer layer deposited by sputtering, which being more numerous and leads to an increase in the number of nucleation sites.
This remark is confirmed by other authors who show that the buffer layer of ZnO with larger grains gives nanowires of ZnO with large diameters [14].
While the first nucleation mode corresponds to fast growth of nuclei on many active sites, the progressive mode corresponds to a slower growth of nuclei on a small number of active sites.
The increase in the density of nanowires and the variation in their diameters seem to be due to the small grain size of the ZnO buffer layer deposited by sputtering, which being more numerous and leads to an increase in the number of nucleation sites.
This remark is confirmed by other authors who show that the buffer layer of ZnO with larger grains gives nanowires of ZnO with large diameters [14].
While the first nucleation mode corresponds to fast growth of nuclei on many active sites, the progressive mode corresponds to a slower growth of nuclei on a small number of active sites.
Online since: March 2015
Authors: Nazila Horandghadim, Abolghasem Dolati, Mohammad Ghorbani
It could be explained that the number of produced charge carriers and the total surface area of nanofilms increased in the thicker TiO2 films that caused to improve the efficiency of photocatalytic activity of films.
Thus the numbers of charge carriers on the surface of TiO2 films enhanced by increasing UV illumination duration.
It could be explained that on the thicker TiO2 nanofilms the number of liberated oxygen atoms and subsequently the adsorbed hydroxyl groups increased which created more hydrophilic TiO2 as described in section 3.6.2.
It was observed that the average grain size and thickness of nanofilms increased with an increase in the applied voltage of EPD from 10 to 60 V for 10 s.
The efficiency of photocatalytic activity of films was found to increase with the TiO2 thickness due to an increase in the number of produced charge carriers and the total surface area of nanofilms.
Thus the numbers of charge carriers on the surface of TiO2 films enhanced by increasing UV illumination duration.
It could be explained that on the thicker TiO2 nanofilms the number of liberated oxygen atoms and subsequently the adsorbed hydroxyl groups increased which created more hydrophilic TiO2 as described in section 3.6.2.
It was observed that the average grain size and thickness of nanofilms increased with an increase in the applied voltage of EPD from 10 to 60 V for 10 s.
The efficiency of photocatalytic activity of films was found to increase with the TiO2 thickness due to an increase in the number of produced charge carriers and the total surface area of nanofilms.
Online since: September 2007
Authors: Guo Wei Ma, Xin Gui Zhang, N.P. Yi, X.L. Chen, H. Wu
However, it can activate linking substance of
clay grains be defined as "soil mini-structure".
A number of cross sections for CT scanning are marked on soil samples before putting into solutions so that a cross section can be observed continuously.
A number of cross sections for CT scanning are marked on soil samples before putting into solutions so that a cross section can be observed continuously.