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Grinding is implemented through actions of a large number of grain edges at the wheel surface on the workpiece.
For a given training set input-output values, the generalization ability of a multi-layered network depends on the number of hidden layers as well as the number of hidden units per layer, therefore, one of the important problems for modeling surface irregularities networks is to select appropriate number of hidden nodes.
This is because, on the one hand, as workpiece speed Vw is raised, the depth of cutting edges increase and their indentation on workpiece surface also rises, as well as the number of active grains per unit area of wheel surface , accordingly the active grains become more uneven, which both result in a raising Ry, and on the other hand, as the depth of cutting edges increases, the wear of the grinding wheel tends to be partial breakage and dig-out of abrasive grains on the wheel surface, which results in an increasing Ry.
Ry increases with a rise in a1, which is related to the deterioration form of wheel surface, and Sm decreases with rise in a1, a2, which indicates that the number of active grains per unit area of wheel surface increases with a1, a2.
When a1, a2 increase respectively to 8 µm/rev, 2.5 µm/rev, and remains increasing a1 or a2, Sm doesn’t vary nearly, which indicates that the number of active grains per unit area of wheel surface doesn’t increase again with a1 or a2.

As the gas sensing is based on adsorption mechanisms on SnO2 grains surface, small grains sizes are desirable to achieve high specific area (adsorption area per volume unity) and thus, high sensitivity.
One can see that grain size reduces as the Ni concentration increases.
Table 1: Specific surface area (SBET) and grain size (DRX) as function of Ni concentration into SnO2.
Figure 2 Shows SnO2 grains and its crystalographic planes.
Figure 2a shows a grain of pure SnO2 where it is possible to verify the tetragonal structure of SnO2 (cassiterite) with grain size around 15 nm.

In addition, the crystal grain size of amorphous and nano-crystalline alloy was small by rapid solidification [10]; the proportion of grain boundaries was large.
The grains directly determine length scale of porosity in the final structure.
The smaller the phase grains, the smaller the pore size.
For a certain composition of Cu-Zn alloy, the zinc quantity is stable, so the number of seepage channels is constant [16].
The smaller the grains, the more the vacancy number, the better for the copper atom rearrangement and zinc atoms diffusion.

The grains in the stir zone are equiaxed and are often by an order smaller than the grains in the base material.
Aspects of the application of this method and the limits of its applicability are considered in the works of a number of authors.
A number of authors have suggested ways to get around this circumstance.
The specific volume of the grains is inconsiderable and do not exceed 2 %.
They are primarily located at the edge of large grains.

Large number of simulations are done for each void fraction to finally get into averaged values for hardness and elastic modulus.
Another possible factor that can cause an increase in hardness is the significant change the shape of the grains for large deformation, i.e. the amount of grain boundaries underneath the tip is very different for different regions of a tensile test specimen: away from the neck, where the grains are still more-or-less equiaxed, the indenter tip 'encounters' much less grain boundary surface than at the neck, where the grains are severely deformed and elongated (Figure 7(b)).
(b) Highly elongated grains in the localized neck of the interstitial-free sample.
Second, elongation of the grains as seen for large deformations (Figure 7(b)) can also cause a decrease in the elastic modulus, as elongated grains exhibit a larger ratio of grain boundary surface to internal grain volume, and the stiffness of a grain boundary is lower than that of the bulk crystal.
Acknowledgments This research was carried out under the project number MC2.02114 in the framework of the Research Program of the Materials innovation institute M2i (www.m2i.nl), the former Netherlands Institute for Metals Research.

However, intergrannular stress supposed to be resulting from the expansion of corrosion products along dissolved grain boundaries is not taken into account in this model.
It is well known that EC occurs in microstructures in which the grain geometry enables easy intergrannular corrosion propagation parallel to the surface exposed.
Fundamental Relationships Used in Improved Application of EC Model for Modeling of Structural Degradation of Al2024 in EXCO Solution Environment The results obtained for alloy L97 exposed to EXCO solution have shown that the effect of exfoliation history from viewpoint of model Robinson for intergrannular penetration observed under blister of given geometry can be written in the form [3]: |for N > 1|, (1) where shape factor S is the ratio of the width (diameter of blister L) to the depth of intergrannular penetration D observed under blister, N is total number of layers of grains penetrated and A is the aspect ratio of the grains.
In this case the vertical grain displacement f (if no local force is applied at their extremities) can be defined by the relationship (2) where E = modulus of elasticity, σg = uniform stress acting on the grain surface in blister plan area and l/w = the average shape factor of grains viewed in LT-ST cross section transverse to L-LT exposition plan area.
Mean grain dimensions were 48.42µm and 11.87µm for the length and the width respectively.

A distinctive feature of ECAP with parallel channels (ECAP-PC) is that, during a single processing pass, two distinct shearing events take place; this means in practice that there is a considerable reduction in the number of passes required for the formation of an ultrafine-grained structure.
The microstructure of grain morphology was observed.
In hot of pressing process (AA1070 + ANF and AA6061 + ANF) the grain was free from micro-crack, so that the formation of the neck grain is easily formed and more uniform.
AA1070 there is not alloy, the possibility of grain bonding more equal than AA6061, heating ECAP-PC process helps the formation of aluminum powder grains bond with reinforcement.
Microstructure of grain a).

Table 1 lists the number of particles emitted and the average energy per particle by natural radioactive isotopes.
The number exceeds the number of traps along the track and all the available traps surrounding track get saturated.
This is required to remove the inter sample or inter aliquot variability occurring due to differences in weight of aliquot and fluctuation in number of bright grains.
However, weight normalization is discouraged due fluctuation of number of bright grains per aliquot.
Presently a number of methodologies are being adopted by different groups.

A number of investigations on hot deformation behavior of nickel base superalloys have been reported in the literature [8-10].
Primary g' phases distribute at grain boundaries as a bright particles, while carbide particles are dark.
The sufficient fine grain size confers superplastic characteristics on the as-extruded material.
The sufficient fine grain size confers superplastic characteristics to the as-extruded material.
Ultimately, the equiaxed, uniform fine-grain structure was formed as a result of dynamic recrystallization.

Heterogeneous microstructure of Ti3SiC2 in this study consists of elongated and equiaxed grain.
The elongated grain was typically ~50 µm long and ~15 µm wide, while the average size of equiaxed grain was ~5 µm.
Cracks were always found to decelerate first and to be arrested finally with the number of cycles.
No obvious bands of grain dislodgment are observed even at 10 6 cycles.
The damage developed with the number of cycles, indicating a mechanical effect.