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Online since: July 2021
Authors: Lyudmila Samchuk, Nataliia Huliieva, Igor Andrushchak, Viktoriya Pasternak, Artem Ruban
Powder materials include a number of properties that need to be controlled in the process of manufacturing structurally heterogeneous materials, which include pressing density, quality and relationship of contacts with each other, grain sizes (particles), component content, shape and size of powders, etc [4, 5, 6].
However, a number of methods for studying powder metallurgy are evaluated ambiguously [13, 14].
The screen number corresponds to the nominal size of the hole in millimetres [23, 24].
This graphic representation of the granulometric composition of the powder of structurally inhomogeneous materials makes it possible to estimate the change in dispersion, the degree of grinding-the ratio of the average grain size of the starting material AlCu2 to the average particle size of the crushed product, as well as specific energy costs.
In addition, the presence of a significant number of non-spherical (non-isometric) particles of AlCu2 powders was revealed, which is most expressed in the dispersed fraction (+0,125-0,1).
Online since: March 2017
Authors: А.V. Nykytynskyj, Irina Bagiyanc, Liudmyla Trykoz
Besides, this study has also demonstrated that concrete with coarse-grained rubber (425 micrometers) has higher electrical resistivity than concrete with fine-grained rubber (75 micrometers).
Table 1: The ratio of the component in the test-beams Input, kg/m3 Sample number 1 2 3 4 5 6 7 8 9 Cement 1950 1950 1950 1950 1950 1950 1950 1950 1950 Sand 5850 5760 5660 5560 5470 5370 5270 5180 5080 Water 780 680 580 480 380 280 180 80 -- Bitumen -- 160 360 560 760 960 1160 1360 1560 Water/Cement 0.4 0.4 0.4 0.4 0.4 0.4 0.4 0.4 0.4 The test-beams were hardening for 28 days, then their electrical resistances were measured by the two-pole method as follows.
Weeks 7 1 2 3 4 5 9 6 1 2 3 4 5 6 7 8 9 10 1,00 1,30 1,60 1,90 2,20 2,50 2,80 3,10 3,40 , Lg R, KOhm KOhm Sample number 8 The electric resistance is measured with the DT9208A multimeter, its technical characteristics corresponding to the following requirements: input electric resistance is 10MOhm; lower measurement range limit is 200mOhm; upper measurement range limit is 200MOhm; inaccuracy is 0.8%.
Figure 2 demonstrates that the samples with greater content of bitumen emulsion (numbers 7-9) have the highest electrical resistance, and the sample without additives (number 1) has the lowest electrical resistance.
Table 2: The ultimate strength limit for test-beams Strength, MPa, for an age Sample number 1 2 3 4 5 6 7 8 9 28 days (humid condition) 14.6 10.3 7.5 7.1 6.8 5.0 4.6 4.3 4.2 56 days (28 days in humid condition + 28 days in dry air) 20.0 18.9 18.2 18.8 14.2 12.2 12.0 11.1 8.0 According to the data from Table 2 replacement of 25% of mixing water by bitumen emulsion leads to lower strength while hardening in water during 28 days.
Online since: August 2012
Authors: Yu Jian Yang, Shu Yun Liu, Wen Jie Feng, Ming Hua Shang
The results also indicated that the estimation accuracy depended on the threshold of sampling numbers, if the numbers are less than the threshold, the sampling density is in contact with the spatial estimation accuracy, if the numbers are more than the threshold, the density of the sampling numbers is improved, but the estimation results are not proportional to the density.
If the numbers are more than the threshold, the density of the sampling numbers is improved, but the estimation result is not proportional to the density, as illustrated in Figure 4 and Figure 5.
The estimation accuracy depended on the threshold of sampling numbers.
If the numbers are more than the threshold, the density of the sampling numbers is improved, but the estimation results are not proportional to the sampling density.
*The National Key Technology R&D Project “study and demonstration of grain risk, warn prognosis and intelligent analysis”(2009BADA9B03)and Innovation Fund Projects of Shandong Academy of Agricultural Science(SAAS).
Online since: December 2011
Authors: Qing Kai Han, Jian Wei Ji, Xiao Xuan Qi, Mei Ling Wang, Li Jing Lin
Secondly, employ empirical mode decomposition (EMD) to the reconstructed signal to obtain a certain number of stationary intrinsic mode functions (IMF).
Statistics show that misalignment faults account for nearly 60% of the total faults number.
An IMF is a function that satisfies two conditions: one is that the number of extreme and the number of zero crossings must either be equal or differ at most by one during the whole dataset; the other is that, at any instant, the mean value of the envelop defined by local minima is zero.
A complex signal can be decomposed into a number of IMFs and a residue.
Jamieson, On the Scalability of 2-D Wavelet Transform Algorithms on Fine-grained Parallel Machines, International Conference on Parallel Processing, 2(1996)24-28
Online since: July 2018
Authors: Anastasia V. Mikhaylovskaya, Anton D. Kotov, Vladimir K. Portnoy, Ahmed O. Mosleh
In addition, the number and the complexity of production operations lead to an increase in the production cost of semi-finished parts of titanium alloys.
Grain boundary sliding and dislocation viscous glide mechanisms are considered when the value of n2 (1/m) of 2 and 3, respectively [33–35].
The dynamic recovery and the recrystallisation processes were confirmed by the grain structure analysis of both alloys in [27].
It can be suggested that such materials constants behaviour is a result of the dynamic grain growth effect [23,36–38].
Zhou, Development of fine-grain size titanium 6Al–4V alloy sheet material for low temperature superplastic forming, Mater.
Online since: October 2022
Authors: Subrata Mondal, Shamim Haidar, Mukandar Sekh, Sarfaraj Ansary, Rafiqul Haque
P/M can also create a fine grain size, which increases the material's homogeneity. [3].
The optical microscope illustrates the sample's pore distribution and it also shows there are powder grains present.
Pore ratios, types, shapes, and sizes, as well as the powder grain size, have a significant impact on the mechanical characteristics of P/M materials. [43].
But the samples content of 99% and 97 % of stainless steel (316L) contained a large number of irregularly shaped pores with sharp edges that accordingly decreases the mechanical properties more likely harnesses ,thus it exerted comparably low hardness value of 350 HV and 344 HV respectively.
The optical microscopic images of these three samples show that the formation of large grain sizes is less likely to occur and that small grains are formed inside the sample structures.
Online since: August 2015
Authors: Zainal Arifin, D. Irawan
Ultrasound technology is used as a modern and very environment friendly process in an increasing number of applications and processes of the chemical industry.
Ultrasonic techniques have been used in the extraction of chitin [4], a protein in grain sorghum [5], and the synthesis of biodiesel from used cooking oil [6].
In the IR spectra also appeared absorption at wave number 1565.30 cm-1 which is the bend vibration N-H of NH2.
The -CH3 bend absorption band at wave number 1319.37 cm-1 is appear but with a weaker intensity, it indicates the occurrence of deacetylation process that led to the loss of most of the methyl groups,-CH3.
Online since: March 2013
Authors: Yan Shu Liu
Intorduction With the advance of science and technology, especially in recent years, aerospace manufacturing, atomic energy, electric power, petroleum equipment etc the rapid development of the industry, the machine and its spare parts material performance put forward higher request. and titanium alloy with its excellent mechanical properties, KangFuXing can, diamagnetic can, resisting high temperature oxidation performance and so on, in the industry has rapidly application..demand titanium alloy tube parts also more and more, especially with high precision requirements of the titanium alloy tube parts number is more and more titanium alloy is is a kind of hard processing material, it's the cutting itself is very difficult, talked about deep hole precision processing that is a difficult task. therefore, how to realize the titanium alloy for deep hole precision machining is the current cheng to solve the problem. this paper through the test of TC11 titanium alloy to choose the suitable
Table 1 The mixed stone proportion of elements Stone Numbers 1# 2# 3# 4# 5# 6# 7# 8# 9# 10# 11# 12# 13# 14# 15# Abrasive composition WA GC SA Each composition The proportion (%/%) 100 100 100 note : 1#-3# Main abrasive for single crystal jade ; 4#-9# Main abrasive for silicon carbide; 10#-12# Main abrasive for white corundum 2.2 sample method and condition The mixed stone are installed in the self-designed deep hole honing tool in the body, the processing parts installed in modified type horizontal deep hole honing machine, specimen aperture forΦ31~35mm,depth 500mm,honing dosage for rotational speed v=20m/min,reciprocating feed speed=10m/min,and the stone constant pressure radial feed way,each stone are continuous complete nine times radial feed cycle after contrast measurement,honing cutting fluid choose kerosene. honing torque is measured by in the drill pipe installed on homemade torque detection device,the measurement system to accomplish data processing
The results and analysis 3.1 Mixed oilstone grinding state before and after Table 2 Titanium alloy test results Stone Numbers Beforehoning diameter (mm) Honing diameter after (mm) Honing remove quantity(mm) Grinding except material volume (mm3) Grinding exceptoil stonevolume (mm3) Grinding ratio Honing torque (N, m) Than grinding can note 1 33.00 33.03 0.03 778 756 1.029 45.10 58.0 sticky 2 33.05 33.09 0.04 1038 832 1.248 39.50 38.1 sticky 3 33.11 33.15 0.04 1040 795 1.308 39.07 37.6 sticky 4 32.74 32.78 0.04 1029 635 1.620 45.51 44.2 Microadhesive, fragile 5 32.79 32.83 0.04 1030 576 1.788 45.31 44.0 Microadhesive, fragile 6 32.85 32.90 0.05 1290 583 2.213 46.30 35.9 Don'tstick, non-friable 7 32.68 32.72 0.04 1027 624 1.646 43.52 42.4 Microadhesive, fragile 8 32.62 32.66 0.04 1025 639 1.604 41.24 40.2 Microadhesive, fragile 9 32.58 32.61 0.03 768 560 1.371 35.86 46.7 Don'tstick, non-friable 10 32.44 32.47 0.03 764 638 1.197 42.40 55.5 sticky 11 32.48 32.51 0.03 765 640
same, in processing parts requirements under the condition of the same precision, using silicon carbide and single crystal corundum mixed stone processing with high efficiency. 2.3 Adhesion and crushing test results Adhesion and crushing test result case as below: Figure1 Honing after 2 # sticky oil stone Figure 4 Honing after 6 # micro adhesive stone Figure 5 Honing after 8 # oil stone Figure 6 Honing 15 # micro adhesive stone The adhesion situation can be seen, alumina content higher oil stone adhesion of the situation is more serious, is mainly due to corundum abrasive grinding of titanium alloy, formation of Ti2O3 and Al2O3 crystal structure with think, lattice parameter close, so produce titanium oxide and corundum has a strong affinity; meanwhile, Ti2O3 in corundum also can form Al2O3, Ti2O3 solution content,make titanium and corundum have strong combination, these are greatly enhanced the titanium and corundum grinding grain
Online since: October 2013
Authors: Quan Yin, Sheng Chun Liu, Liang Jun Xu
Introduction Through the study of a large number of communication terminal products found that contact fretting failure is one of the main reasons leading to the invalid connector.
This is because when the contact pressure increases, the two contact surfaces move close to each other, contact number of spots increases so that the real contact area increases, reduce the resistance.
Table 2 Test results Test results Photos Numbers force(g) A(mA) V(mV) R(mΩ) State a 100 100 1.176 11.76 partial pressed b 100 100 550 5500 just pressed c 100 100 550 5500 just pressed d 100 100 3.506 35.06 crushed e 150 100 0.705 7.05 partial pressed f 150 100 0.635 6.35 crushed g 150 100 550 5500 just pressed h 150 100 0.961 9.61 crushed i 150 100 550 5500 just pressed j 150 100 3.506 35.06 crushed k 150 100 2.891 28.91 crushed (a) (b) (c) (d) (e) (f) (g) (h) (i) (j) (k) Fig.2 Photos of 70-150μm particles after pressed It is being seen from table 2, 70-150 silica particles results in a larger change.
The presence of silica particles is increased at least 3 times than clean samples; when other experimental conditions do not change only increase the contact pressure, regardless of grain contact resistance will decrease. 2.
Online since: June 2014
Authors: Xiu Lan Sun, Yu Zhu Shang, Mao Lei, Cheng Hang
Table .1 The granite residual soil weathering degree hierarchical table level number the soil composition and structure differences the engineering specification 1 Even the red soil layer Sand, gravel, clay 2 Checkered red soil Sandy clay powder, clay content is higher 3 Mottled clay layer Gravel, clay or silt, sandy powder locally for coarse sand in clay Combined part of about 75% of the total area of the region, mountainous hilly region of slope surface covered with widely, the residual soil thickness usually within 6 meters, affected by geological structure after the quake, shallow landslide in heavy rainfall weather easily happened.
Table.2 Earthquake eluvia soil the soil physical and mechanical properties Name Color thickness (m) Gravel particles (%) sand (%) silt (%) clay (%) ρ(g/cm3) C (kPa) Φ (°) e Sand clay Red-brown 0.5-7 0.1-28.0 20.9-47.0 10.7-38.0 22-55.6 1.57-1.90 8.9-70.0 12.0-35.0 0.8-1.07 Pink clay brown 5-15 15.0-34.0 10.0-55.0 8.0-38.0 10.5-34.0 1.63-1.78 8.9-50.0 18.6-33.0 0.72-1.13 silt Brown spots >10 15.0-47.0 42.3-67.0 8.0-30.2 4.0-13.0 1.66-1.93 10.0-40.0 24.0-35.0 0.63-1.04 On the grain size distribution of it in residual soil from top to bottom, with the increase of weathering degree, significantly reduce the content of clay, gravel content.Eluvia soil layers soil density from top to bottom with the reduce of void ratio increases gradually, basic is within the scope of 1.75 to 2 g/cm2, pore ratio is between 0.8 0.99 distribution, pore ratio is larger.Eluvia soil cohesion around from top to bottom with the loss of the clay content decreases, and the internal friction Angle are increased
The experimental principle and the result analysis This subject adopts the random simulation method, its basic principle is: the probability of an event can use a large number of trials to estimate the incident frequency, according to Tchebycheff procedure, cutting of large Numbers theorem, when the sample size is large enough, the frequency of the event can be considered as its probability.
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