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Online since: May 2011
Authors: Chang Hu Yang, Zhong Quan Ma
It is clear the grain boundaries at low substrate temperature (in Figure 1 (a) and (b)), but the gaps between columnar grains decrease with increasing substrate temperature.
In fact, The average grain diameter (D) as a function of the temperature (T) can be expressed using following formula[16]: (1) where Qm is the activation energy of grain boundary, R is the the gas constant, and C is the proportional coefficient.
Therefore, when the substrate temperature increases, the grain size of the AZO films will increase.
Table 1 Grain size, diffraction peak position and FWHM of AZO thin films substrate temperature [oC] grain size [nm] 2θ [0] FWHM [0] 150 6.9 33.90 1.20 250 7.0 33.92 1.18 350 13.8 33.72 0.60 450 26.0 33.88 0.32 Effect of substrate temperature on the optical properties of AZO thin films.
If we assume that the Fermi surface is spherical, the following well-known formula is given[19]: (5) Here, is the BM shift, is Fermi wave number, is the reduced effective mass, ne is the carrier concentration and A is a scale factor.
Online since: April 2008
Authors: Graeme E. Murch, Irina V. Belova
This phenomenological diffusion problem is treated by overlaying it with a fine-grained lattice that was addressed using a Lattice Monte Carlo method and a little-known exact expression for the lattice-based effective diffusivity in the presence of random traps.
The Model In keeping with the spirit of the LMC method [2] a fine-grained lattice is constructed to overlay the phenomenological diffusion problem.
Results and Discussion The expression Eq. 4 for the effective diffusivity was first verified by making use of the EinsteinSmoluchowski Equation: Deff = / 4t (5) where R is the displacement of a given particle in time t and the Dirac brackets < > indicates an average over a large number of particles.
Eq. 5 is readily realized in an equilibrium simulation wherein completely non-interacting particles are permitted to diffuse in a lattice containing random traps for a fixed number of jump attempts per particle (proportional to time) [2].
Gust, Fundamentals of Grain and Interphase Boundary Diffusion, Wiley, Chichester, 1995
Online since: February 2022
Authors: Stanislav G. Danilchenko, Anton V. Petrukhin, Konstantin F. Selemenev, Gennady V. Barsukov, Olga G. Kozhus, Dmitry I. Titov
It is noted that in the process of applying the polymer shell to the surface of the abrasive grain in the fluidized bed, the effect of slippage and the absence of the influence of the installation wall on the value of the longitudinal velocity of particles near it is observed, which allows to increase the productivity of creating an abrasive-polymer compound.
Introduction In the technology of waterjet cutting, the tool is a supersonic jet of liquid with abrasive grains [1, 2].
Main Part The productivity of applying the polymer shell to the surface of the abrasive grain in the fluidized bed is estimated as the mass of the processed material per hour of operation of the installation.
It is largely random, particles collide with each other, collisions (with rare exceptions) can be considered elastic, the number of particles per volume unit does not change over time.
, (3) where t is the time; is the radius-vector of a material point simulating a moving particle at time t; , is its speed and acceleration at this moment; is the Hamilton differential operator by argument , - by argument ; is the six-dimensional elementary volume of the phase space centered at the point where the material point falls with probability at time t (n is the number of particles per volume unit); J is the collision term of the equation; is the density function of the distribution of particles according to their positions in the geometric space and the velocity space at different moments of time; is convolution-scalar multiplication sign.
Online since: August 2012
Authors: Yang Huan Zhang, Hui Ping Ren, Dong Liang Zhao, Tai Yang, Ying Cai, Hong Wei Shang
The substitution of Pr for La results in a notable grain refinement of the as-cast alloys without altering the phase structure of the alloys.
It displays that the substitution of Pr for La results in the visible refinement of the grains of the as-cast alloys.
The activation capability was indicated by the number of charging-discharging cycles required for attaining the greatest discharge capacity through a charging-discharging cycle at 100 mA/g current density.
The enhanced discharge capacity by melt spinning is ascribed to the refinement of the grain produced by melt spinning because the grain boundary exhibits the distribution of the maximum hydrogen concentrations.
The substitution of Pr for La results in the obvious refinement of the grains of the alloys instead of changing the phase compositions of the alloys.
Online since: February 2013
Authors: Feng Wang, Xi Wu Li, Zhi Hui Li, Yu Ting Zuo, Hong Wei Liu, Yong An Zhang, Bai Qing Xiong
The microstructure of the fusion zone has been found to be very fine equiaxed grains, and the microstructure of the heat affected zone is mainly composed of α-Al and Al/MgZn2 eutectic microstructure.
As a result, a number of drawbacks that the powder metallurgy possesses, such as multi-step processing and easy powder contamination by oxygen, no longer exist in spray-deposited process[6].
Fig.1(c) shows the OM micrograph of heat affected zone (HAZ) in the joint, it can be seen that the microstructure of the HAZ consists of elongated grain morphology with recrystallized characterization.
The morphology of fracture surface examined by SEM (Fig.6(b)) showed flat fusion zone, and high magnification by SEM of the fusion zone has been found to be very fine equiaxed grains.
The microstructure of the fusion zone has been found to be very fine equiaxed grains, and the microstructure of HAZ is mainly composed of α-Al and Al/ MgZn2 eutectic microstructure.
Online since: May 2011
Authors: Jian Dong Ding, Ying Lei, Wei Dong Lu, Ding Zhou, Wei Qing Liu, De Liang Xu
The mechanical properties of single-bolted steel-glulam-steel connection subjected to a load parallel to the grain have been studied.
Experiment Program The experimental test concerns with seven groups of joints parallelly loaded to the grain.
(3) (4) where Fyu (N) is the minimum yield resistance, ns is the number of shear planes, nf is the number fasteners in joint, fv avg (N /mm2) is the glulam shear strength, k1s is the factor to account for the shear area, a (mm) is the end distance of the bolt.
Table 2 Comparison of theoretical and experimental results for the average ultimate loads Specimens Failure Model Fu [kN] Experimental Average Equation1-4 Deviation[%] 12d-27 I 16.364 16.294 0.43 12d-47 I 29.300 28.364 3.30 12d-77 III 42.095 40.849 3.05 12d-107 III 50.458 40.849 23.52 14d-107 Bearing 60.435 57.696 4.75 18d-107 Row-shear 79.931 77.521 3.11 20d-107 Row-shear 94.558 96.471 1.98 Summary Through the present study, it is found that the failure modes, stiffness, ductility and bearing capacity of the single-bolted steel-glulam-steel joints under the load parallel to the grain are mainly influenced by the thickness of the glulam and the diameter of the bolt.
Predicting the Row Shear Failure Mode in Parallel-to-Grain Bolted Connections.
Online since: March 2013
Authors: Fu Xian Zhu, Ji Yuan Liu, Shi Cheng Ma
By the rising of the annealing temperature, bainite grains are appeared in sample C which can observe in SEM image pointed by arrow (Fig. 3(c)) imply the cooling rate is not enough for the martensite transformation in some austenite grains with low hardenability[4, 5].
Both of the ferrite and martensite grains are increase in size within the annealing temperature rise.
Fig. 4 shows the typical transformation phase of different samples that mass of carbides are found beside the martensite grains (pointing by arrow) in sample A, meanwhile, twin martensite appears in the sample B, with a large number of dislocation beside it, lamellar carbide precipitation occurred in ferrite in sample C in the cooling process which create the bainite phase.[6, 7] Fig. 3 Microstructure of tested steels (a) sample A; (b) sample B; (c) sample C.
The undissolved pearlite develop into spheroidized carbides as shown in Fig. 4(a), perform as hard phase in the deformation which can enhance the UTS but worsening the elongation by gather a large number of dislocations as a source of crack[9].
So the bainite grains appears in the microstructure of sample C, the lack of martensite cause a lower UTS and the lamellar carbide make the elongation decrease[10].
Online since: April 2012
Authors: Soma Prasad, Aloke Paul
The presence columnar grains indicate that there could be some contribution from the grain boundary diffusion.
Since the number of Si-Si bonds is much less but the diffusion rate is much higher compared to the metal species, a high Si antisite concentration is expected in both the structures to ensure higher diffusion rate of Si.
While it is justifiable from the number of the nearest neighbour atoms in the XSi2 phase, it is rather abnormal for the X5Si3 phase, where Si is faster despite of very few or no nearest neighbour atoms.
All the disilicides show the presence of the columnar grains and indicates contribution from grain boundary diffusion.
Actually we measure the apparent diffusion coefficients and it is difficult to quantify the exact contribution from lattice and grain boundary diffusion.
Online since: August 2012
Authors: Hong Hua Wu, Jun Chen, Chui Wei Lu
The annual turnover number for a large hospital could reach at least one million; accordingly, the number of medical records for a corresponding hospital could reach millions.
If the system is subdivided, the numbers of modules are increased.
By coarse-grained division, the complexity of the system is under control.
Hierarchical structure of systems and fine-grained particles E.
As a result, the number of key words could reach 3,000.
Online since: May 2014
Authors: Takayoshi Nakano, Ai Serizawa, Tomoki Tanaka
The grain showed an elongated dendritic morphology and aligned along the build direction during laser beam sintering.
Thus, the microstructure involving the grain morphology and crystallographic texture formation was anisotropically controlled by laser beam sintering technique.
A short implant life is a severe problem, especially for the growing number of younger patients who are required to use hip implants, because of their prolonged remaining life and active lifestyle.
The grain showed an elongated dendritic morphology and aligned along the build direction during LBS.
The grain morphology as well as crystallographic texture formed responsible for the unidirectional heat flow along the build direction.
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