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Online since: November 2012
Authors: Jarosław Sep, Pawel Pawlus, Andrzej Dzierwa
Journal and bearing sleeve (w – groove width, dg – groove depth) - contaminants: Al2O3 powder of mean grain diameter- 21 μm, - contaminant concentration in oil - 0.5 g/l.
One can see higher number of valleys on classical journal surface with comparison to modified journals.
Smaller contaminants concentration in case of modified journal is connected with smaller number of valleys on its surface, which can be quantitatively described by larger values of the spatial parameters Sal and Str, comparing to classical journal surface.
Online since: April 2008
Authors: Jian Hua Wu, Ying Jin, Zheng Qiang Yao, Yong Jun Shi, Hong Shen
All the three mechanisms are determined by the temperature field which is influenced by geometry of workpiece, laser spot diameter, scanning velocity, scanning number and path, etc.
A large number of research works on macro workpieces have been carried out.
Size effect and MSG theory As laser bending sheet size becomes small to a microscale, the material behaviour in micrometal forming differs from that in conventional forming because of different factors, such as the grain size.
Online since: October 2006
Authors: Maurizio Fermeglia, Marco Ferrone, Paolo Cosoli, Maria Silvia Paneni, Roberta Venica, Sabrina Pricl, Sabino Sinesi, Paola Posocco, Laura Martinelli
The theory underlying the methodology for the calculations of the next set of MS input parameters - the number Nmeso and the bond length a of the MS beads - is similar to the classical dynamic random phase approximation (RPA) [5,6].
The polymer chains are modeled as Gaussian chains consisting of beads, each bead representing a number of monomers of the real polymer.
All MS simulations have been performed with MesoDyn, a coarse grained model for the diffusive and hydrodynamic phenomena in phase-separation dynamics [8].
Online since: February 2006
Authors: Didier Priem, Surendar Marya, Guillaume Racineux
The magnetic pressure, created by the inductive current pulses or oscillations can be approximated as: ( ) 2 2 2 2 0 2 sin 2 Rt L K n U C t e P LI µ ω   −    = (1) where µ0 is the magnetic permeability (in H/m), K is a coefficient depending upon the physical dimensions of the coil, n is the number of windings of the coil, ω is the LC oscillation frequency, R is the total resistance of the discharge circuit (in Ω) and t is the time (in s).
From the peripheral elongation with different discharge energy diagrams at varying static pressures, it is explicit that at about 10KJ, the initial static would not have any effect on overall elongations. 0 5 10 15 20 25 30 35 0 1 2 3 4 5 6 7 8 Ps=0 MPa Ps=20 MPa Ps=40 MPa Ps=60 MPa Peripheral elongation (%) Energie (kJ) 1 2 3 4 5 6 7 8 -10 0 10 20 30 40 50 60 70 5 % 10 % 15 % 20 % 25 % Energie (kJ) Ps (MPa) Fig. 7 - (a) Peripheral elongation versus discharge energy for different static pressures, (b) constant elongation curves in Pressure-Energy diagram The metallographic structure of grains is not significant except near the sharp change of curvature of the tube (point 2) in the expansion region (Fig. 8.a).
a. b. 100 120 140 160 180 200 220 240 1 1,2 1,4 1,6 1,8 2 1 2 3 4 5 6 7 Hv Post forming thickness (mm) Initial thickness (mm) Hv Initial Thickness (mm) Point number Fig. 8 - (a) Optical micrographs of deformed tube (Ps = 40MPa and E = 8kJ), (b) Hardness and post forming thickness Conclusions From this short technical presentation of high speed forming work under progress, some of the main features may be described.
Online since: November 2005
Authors: Kikuo Kishimoto, Akira Shinozaki, Hirotsugu Inoue
Hiroo [4], studied the coarse-graining is applied to flexible polymer chains.
(a) Model A (b) Model B (a) Model A (b) Model B Fig. 6 Network model before relaxation Fig. 7 Network model after relaxation 0 0.1 0.2 0.3 1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 Segment Number Weight Fraction 0 0.1 0.2 0.3 1 4 7 10 13 16 19 22 25 28 31 34 37 Segment Number Weigth Fraction (a) Model A (b) Model B Fig. 8 Molecular weight distribution (a) Stretch Ratio 1.24 (b) 1.72 (c) 1.96 (d) 2.44 Fig. 9 Deformation process of model A 1 1.5 2 2.5 0 10 20 30 Stratch Ratio Stress [MPa] Model A Model B Fig. 10 Stress-stretch ratio curve (a) Stretch Ratio 1.24 (b) 1.72 (c) 1.96 (d) 2.44 Fig. 11 Deformation process of 5% deleted model A (a) Stretch Ratio 1.24 (b) 1.72 (c) 1.96 Fig. 12 Deformation process of 20% deleted model A (a) Stretch ratio 1.24 (b) 1.72 Fig. 13 Deformation process of 60% deleted model A Fig. 14 Change of fracture
Online since: August 2006
Authors: Wilfried Wunderlich, Francis D. Gnanam, Krupathi Vishista, Daniel Doni Jayaseelan
MD simulations showed [14], that at particles below 5 nm surface relaxations lead to a tremendous increase of the enthalpy and this increase is different for each of the phases alumina, magnesia and spinel, in particular, magnesia with its strong ionic bonding character shows a relatively low increase, while spinel has the steepest increase, indicating that high symmetric crystal structures with high coordination number and few atoms per unit cell are more stable than those with less number of bonds or high probability for stoichiometric vacancy defects.
The reaction in the sol-gel process occurs in grains with nano-dimensions, and these nano-size effects especially depend on the process parameters.
Online since: December 2013
Authors: Xiao Hui Zeng, Yan Ke Yang, Jun Lei Tian, Jian Qiang Cheng
Orthogonal test group are shown in table 3: Table3:Grouping test table The test number 0mm~0.075mm(%) 0.075mm~5mm(%) 5mm~10mm (%) 10mm~20mm (%) 20m~31.5mm(%) Water (%) SF3 3 22 15 25 35 According to the situation SF5 5 20 15 25 35 SF8 8 17 15 25 35 SF12 12 13 15 25 35 2.The research of the basic characteristics of graded crushed stone frost heave 2.1 The effect of fine powder content on the frost heave of graded crushed stone Different fine power content of frost heaving experiment results are shown in table 4: Table 4 Different fine power content of frost heaving experiment results SF12 SF8 SF5 SF3 the water mass fraction(%) amount of frost heave (%) the water mass fraction(%) amount of frost heave (%) the water mass fraction(%) amount of frost heave (%) the water mass fraction(%) amount of frost heave (%) 8.036 1.680 7.669 1.378 9.319 0.919 9.416 0.576 7.213 1.316 6.222 0.913 6.941 0.629 7.138 0.517 6.596 1.068 5.544 0.785 5.380 0.496 5.575 0.399 5.786
with the increase of fine powder content.According to the results of the test, different fine powder content of frost heaving ratio’s relationship with the water mass fraction is shown in fig. 2 Fig. 2 The relationship of different fines content rate of frost heave with the water mass fraction In Fig.2,we can see that the relationship of quality moisture content and the rate of frost heave is linear.And different fines concent has their own initial moisture content of frost heave.When the frost heaving ratio is 0, the moisture content is the initial moisture content of frost heave. 2.2 The curve of frost heaving ratio along with the change of temperature With different powder content of graded crushed stone under the condition of the filled with water, the frost heaving ratio under different temperatures is shown in table 5: (o(C)温 度 组 别 Table5 The frost heaving ratio under different temperatures tempe frozen-heave (oC) factor (%) test number
[4] Wang Zhengqiu.The impact of the grain size composition to the frost heave of fine sand[J].
Online since: October 2013
Authors: Wen Qing Zhang, Xu Guang Liu, Yuan Li, Xu Ning Liu
Topology model describes the relationship between the various parts of the composition and distribution of plant, the type of organ, the number, location and the structural relationship between each other at every stages of growth; The geometric structure model describes the structure of plant and 3D geometric information of organs, such as organ size, shape and angle.
The research on simulation model of plant uses the traditional mathematical methods such as mathematical statistics, partial differential equations and nonlinear function, artificial intelligence methods such as expert systems, neural networks, the fuzzy system, genetic algorithm, the theoretical generalization and abstract data of plant development are used to take a large number of experimental data plant development and yield to identify the dynamic model of plant growth and relationship with the surrounding environment, and then on the computer plant growth is made simulation in the entire life cycle within a given environment, which is used to direct plant production management and decision-making, then forecast production or breeding[3].
Implementation Growth models include two parts of the program design and dynamic control indicators, the design knowledge model includes the production target, variety selection, sowing time, population density and sowing the amount of calculation, strategy and water management; Dynamic control of knowledge model of regulation indicators includes appropriate growth period, the dynamic leaf age, leaf area index dynamics and dry matter accumulation of dynamic growth index dynamic and effective leaf area ratio, efficient leaf area ratio and the grain-leaf ratio bell leaves the ratio of the source library indicators.
Online since: May 2023
Authors: Mahmoud M. Abd El-Razik, Mervat Gaber Eisa, Hesham Sameh
The grain size distributions of both EPS and RWG along with the upper and lower acceptable/ standard limits of ASTM C33 [7] are presented in Fig.3.
The considerable reduction in TC is attributed to the high number of air voids created by EPS. % RWG possessed TC values less than the limit prescribed for thermal insulation mortars as per BS EN 998.
The considerable reduction in TC is attributed to the high number of air voids created by EPS [12].
Online since: November 2014
Authors: Bin Zhao, He Zhao, Ji Jun Xue
There are many facets source region, the expansion area is along the grain characteristics and the final fracture zone is characterized by cleavage.
At the interface of the layered structure, there is a large number of micro-defects[4].
When the cracks extended the solder alloy layer and the substrate interface, there were two possibilities to be considered: if there were a large number of microscopic defects between the interfaces, the combination of the solder alloy bonding layer and the substrate would be weak, and it would form an interface crack, leading to the lamination between the solder alloy layer and the interface layer, even peeling; while if the interface had less microscopic defects, the combination of the solder alloy layer and the substrate would be stronger, the part can be seen as a notched specimen, the matrix at the part would generate stress concentration, resulting alloy layer deposited weld cracks within the matrix through the interface into the fracture [6]
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