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Online since: September 2007
Authors: Shan Suo Zheng, Shun Li Che, Lei Li, Liang Zhang, Qin Zhao
With enlarging continuously of the fracture number of tiny springs, nonlinear
characteristic of stress-strain curve will become more and more remarkable.
When load reaches a certain value, namely the damage of concrete develops to certain extent, the stress starts to lower although strain continually enlarges in the tiny unit body that the number of ruptured tiny springs is excessive.
Compressive stress and friction coefficient between steel and concrete vary in accordance with the thickness and grain size of the damaged concrete layer at the moment.
If ik represents the stiffness of the spring i, there exists 12 i n k k k k = = = = = L L , where n is the number of springs in a damage body.
(3) Where, K is initial bond stiffness of damage body, which involves the properties of damage body itself and is determined by the bond-slip curve fitted by experiment data [3]; D is damage variable and it is defined as the ratio of the number of damage springs and the total number of springs, namely ( ) ( ) ( )( ) 1 0 1 n N i i D n N H N H x dx ε ε δ ε δ →∞ = = = − → − ∑ ∫ .
When load reaches a certain value, namely the damage of concrete develops to certain extent, the stress starts to lower although strain continually enlarges in the tiny unit body that the number of ruptured tiny springs is excessive.
Compressive stress and friction coefficient between steel and concrete vary in accordance with the thickness and grain size of the damaged concrete layer at the moment.
If ik represents the stiffness of the spring i, there exists 12 i n k k k k = = = = = L L , where n is the number of springs in a damage body.
(3) Where, K is initial bond stiffness of damage body, which involves the properties of damage body itself and is determined by the bond-slip curve fitted by experiment data [3]; D is damage variable and it is defined as the ratio of the number of damage springs and the total number of springs, namely ( ) ( ) ( )( ) 1 0 1 n N i i D n N H N H x dx ε ε δ ε δ →∞ = = = − → − ∑ ∫ .
Online since: January 2011
Authors: Tsuyoshi Kajitani, Yuzuru Miyazaki, Kunio Yubuta, Kei Hayashi, X.Y. Huang, W. Koshibae
In a high temperature range, the Seebeck coefficient of a strongly correlated system becomes almost constant at a value formulated by Chaikin, Beni [23] and Koshibae et al. [24] as,
where, g; total number of configurations, N; total number of carriers.
The g-term becomes, where, NA, M; system size, number of Co4+ ions.
Figure 9 shows the possible numbers, g3 and g4, of spin states of the Co3+ and Co4+ ions [24].
The grain sizes of the sintered powder samples, which changed during the sintering process, are shown in the insets.
Fig.17 Power factor, PF=S2/ρ (a), and ZT (b) vs. temperature curves of the commercially available fine grain Ga-doped ZnO.[47] Diameter of the sintered ZnO grain sizes are shown in the insets.
The g-term becomes, where, NA, M; system size, number of Co4+ ions.
Figure 9 shows the possible numbers, g3 and g4, of spin states of the Co3+ and Co4+ ions [24].
The grain sizes of the sintered powder samples, which changed during the sintering process, are shown in the insets.
Fig.17 Power factor, PF=S2/ρ (a), and ZT (b) vs. temperature curves of the commercially available fine grain Ga-doped ZnO.[47] Diameter of the sintered ZnO grain sizes are shown in the insets.
Online since: June 2006
Authors: Algirdas Vaclovas Valiulis, O. Chernashejus, Vitalijus Rudzinskas
The number of potentially dangerous equipment that has completed its established
operational time, but is still being used, is permanently increasing.
The uniform boundaries of dislocations in the volume of a ferrite grain create sub-boundaries.
At investigation of the dislocation structure of neutral layers of an elbow metal the great number of micro-pores and dislocation near carbides were determined (Fig. 3 d).
This great number of micro-pores in neutral layers of an elbow metal is formed at the combined stress, which appears because of an oval of an elbow and a diffusion of vacancies while it is being maintained.
Definition of ultimate amplitudes of the relative elastic stress [σaF] or ultimate number of cycles [Nа] is carried out in view of reliability criterions (a rigid loading) (Fig. 7).
The uniform boundaries of dislocations in the volume of a ferrite grain create sub-boundaries.
At investigation of the dislocation structure of neutral layers of an elbow metal the great number of micro-pores and dislocation near carbides were determined (Fig. 3 d).
This great number of micro-pores in neutral layers of an elbow metal is formed at the combined stress, which appears because of an oval of an elbow and a diffusion of vacancies while it is being maintained.
Definition of ultimate amplitudes of the relative elastic stress [σaF] or ultimate number of cycles [Nа] is carried out in view of reliability criterions (a rigid loading) (Fig. 7).
Online since: July 2012
Authors: Shun Xi Wang, Pei Han, Ning Bo Leng
cccccoverslip, take the sample slide under the microscope, adjust the brightness of the field of view,observing the slide under the microscope, measuring the particle occupied lattice number on scale or near on scale ,or count on the horizon : 1 below the number of particles, 1 to 2 the number of the particles and accounted for more than 2 the number of particles.为了获得统计上正确的平均,至少统计500个粒子。
The formula体积平均粒径公式如式3.1所示: of volume average particle size as formula (1): (1) 式中 n i表示第 i 区间内颗粒的个数; d i表示第 i 区间内颗粒的平均直径;式中 i 为微粒体积平均直径; d i为某一粒径范围的中心值,粒径范围分别为 0 ~12um,12~15um,15~ 2 0um,和20um以上Where ni represents the number of particles in the interval of the i; di represents the average diameter of particles in the interval of the i; where i is the average diameter of the particle volume; di is the values of center in a range of particular size, the particle size range were 0 -12um, 12-15um, 15 - 20um, and 20um above. n is the fire extinguishing agent particle number of 1.3.2 斥水性falls within the range of grain diameter.
Compared the performance test index with fine dry powder extinguishing agent standard of GA578-2005 of China, showing that the rate of moisture absorption, water repellency, bulk density values are in conformity with the relevant standards, mobility is also very good. 2.3草原火灾灭火剂灭火效能The fire extinguishing effectiveness of grassland fire extinguishing agent 2.3.1不同粒度灭火剂灭火效能研The fire extinguishing effectiveness of different particle size fire extinguishing agent 实验中草原火灾灭火剂的灭火用量受许多因素的影响,一般某种粒度灭火剂用量处于一个用量范围区间之中,见表6所Experiment of grassland fire extinguishing agent fire extinguishing dosage is affected by many factors, the general dosage of a certain grain size agent at a interval, shown in Table 6.
And with the increase of the fire extinguishing agent particle size, the scope of the minimum dosage of extinguishing agent is gradually increasing; illustrate the smaller of the fire extinguishing agent particle size, the smaller of the extinguishing agent dosage. 2.3.ND1添加剂Study on the characteristics of ND1 additive 为了提高草原火灾灭火剂的灭火效能,显著降低草原灭火剂成本,通过大量的筛选试验研究,终于找到一种草原灭火剂添加剂ND1,并对ND1的工作特性进行了一些试验研In order to improve the fire extinguishing efficiency of grassland fire extinguishing, significantly reduce the cost of grassland fire extinguishing agent, through a large number of screening tests, finally found a grassland fire extinguishing agent additives ND1 , and carried out some experimental research for the characteristic of ND1.The result is shown in Table7 and Fig.6 表 7 ND1 添加量与最小灭火剂用量的关系Table7 Addition amount of ND1and the minimum dosage of fire extinguishing agent Table 7 Addition amount of ND1 and the minimum dosage of fire extinguishing agent 灭火剂性能 Extinguishing agent performance
The formula体积平均粒径公式如式3.1所示: of volume average particle size as formula (1): (1) 式中 n i表示第 i 区间内颗粒的个数; d i表示第 i 区间内颗粒的平均直径;式中 i 为微粒体积平均直径; d i为某一粒径范围的中心值,粒径范围分别为 0 ~12um,12~15um,15~ 2 0um,和20um以上Where ni represents the number of particles in the interval of the i; di represents the average diameter of particles in the interval of the i; where i is the average diameter of the particle volume; di is the values of center in a range of particular size, the particle size range were 0 -12um, 12-15um, 15 - 20um, and 20um above. n is the fire extinguishing agent particle number of 1.3.2 斥水性falls within the range of grain diameter.
Compared the performance test index with fine dry powder extinguishing agent standard of GA578-2005 of China, showing that the rate of moisture absorption, water repellency, bulk density values are in conformity with the relevant standards, mobility is also very good. 2.3草原火灾灭火剂灭火效能The fire extinguishing effectiveness of grassland fire extinguishing agent 2.3.1不同粒度灭火剂灭火效能研The fire extinguishing effectiveness of different particle size fire extinguishing agent 实验中草原火灾灭火剂的灭火用量受许多因素的影响,一般某种粒度灭火剂用量处于一个用量范围区间之中,见表6所Experiment of grassland fire extinguishing agent fire extinguishing dosage is affected by many factors, the general dosage of a certain grain size agent at a interval, shown in Table 6.
And with the increase of the fire extinguishing agent particle size, the scope of the minimum dosage of extinguishing agent is gradually increasing; illustrate the smaller of the fire extinguishing agent particle size, the smaller of the extinguishing agent dosage. 2.3.ND1添加剂Study on the characteristics of ND1 additive 为了提高草原火灾灭火剂的灭火效能,显著降低草原灭火剂成本,通过大量的筛选试验研究,终于找到一种草原灭火剂添加剂ND1,并对ND1的工作特性进行了一些试验研In order to improve the fire extinguishing efficiency of grassland fire extinguishing, significantly reduce the cost of grassland fire extinguishing agent, through a large number of screening tests, finally found a grassland fire extinguishing agent additives ND1 , and carried out some experimental research for the characteristic of ND1.The result is shown in Table7 and Fig.6 表 7 ND1 添加量与最小灭火剂用量的关系Table7 Addition amount of ND1and the minimum dosage of fire extinguishing agent Table 7 Addition amount of ND1 and the minimum dosage of fire extinguishing agent 灭火剂性能 Extinguishing agent performance
Online since: May 2024
Authors: Mohamed Abdelgawad Gebril, Mohamed S. Melad, Farag M. Shuaeib, Rafaa M. Esmaael, Mohamed A. El-Hag
They found that the multi-pass welding procedure resulted in grain growth at the heat-affected zone (HAZ) and secondary austenite precipitation in the weldment.
The researcher discovered that large ferrite grains become supersaturated with nitrogen in high ferrite concentrations, which can cause the development of Cr2N in the HAZ and WM.
However, they observed Cr precipitation on the grain boundary upon visual inspection.
Therefore, the increase in hardness in WZ of the design point number 9 is attributed to the increase in ferrite volume fraction.
The HAZ of design point number 15 has an austenite volume fraction of 42%, while design point number 4 has a much higher austenite volume fraction of about 56.5%.
The researcher discovered that large ferrite grains become supersaturated with nitrogen in high ferrite concentrations, which can cause the development of Cr2N in the HAZ and WM.
However, they observed Cr precipitation on the grain boundary upon visual inspection.
Therefore, the increase in hardness in WZ of the design point number 9 is attributed to the increase in ferrite volume fraction.
The HAZ of design point number 15 has an austenite volume fraction of 42%, while design point number 4 has a much higher austenite volume fraction of about 56.5%.
Online since: September 2016
Authors: Aleksey N. Shapovalov, R.R. Dema, S.P. Nefedyev
Average monthly performance of the sinter plant
Indicators
The performance value for the period
Specific productivity, [t/(m2•h)]
0.93-1.15 / 1.11
The vertical speed of sintering, [mm/min]
17.34-24.01 / 20.32
The content of fine-grained concentrates in the charge, [%]
56.1-69.6 / 62.0
The vacuum in the reservoir, [kPa]
4.74-6.71 / 5.76
The height of the charge layer, [mm]
248-305 / 277.6
The returns content in the charge, [%]
22.5-27.5 / 25.2
The charge temperature, [°C]
40.0-61.0 / 51.6
The carbon content in the charge, [%]
3.27-5.09 / 4.04
Lime consumption, [kg/t]
17.9-30.1 / 28.8
The iron content in the sinter, [%]
50.3-55.4 / 52.7
The sinter basicity for CaO/SiO2, [u]
1.33-1.85 / 1.58
The fines content in the sinter (FR. 0-5 mm), [%]
13.7-17.0 / 15.7
Strength values, [%]: shock
65.0-72.3 / 68.2
abrasion
4.9-5.4 / 5.2
Note: in the numerator – changes interval, in the denominator - the average value.
Despite the limited amount of fine-grained concentrates in the sinter charge, acceptable specific lime consumption (29 kg/t) and the hot return use, the performance indicators of the sinter charge production of the JSC "Ural Steel" are among the lowest in the industry.
This, along with poor technical condition of exhaust gases path, limits the height of the sintered layer, the productivity of the shop and prevents the fine-grained concentrates increase [2 – 4].
Producing a more uniform grain size of the pelletized charge with a minimum amount of fines contributes to the increase of porosity of the sintered layer, and the higher strength of sinter charge pellets allows maintaining high gas permeability during sintering, preventing compaction of the charge under the action of vacuum.
The most significant increase in strength characteristics of the sinter charge was observed if surfactant consumption was 1.6 l/h when the number of the fines formed after flushing was reduced from 10.5 – 11.0 % to 8.5 – 9.5 %.
Despite the limited amount of fine-grained concentrates in the sinter charge, acceptable specific lime consumption (29 kg/t) and the hot return use, the performance indicators of the sinter charge production of the JSC "Ural Steel" are among the lowest in the industry.
This, along with poor technical condition of exhaust gases path, limits the height of the sintered layer, the productivity of the shop and prevents the fine-grained concentrates increase [2 – 4].
Producing a more uniform grain size of the pelletized charge with a minimum amount of fines contributes to the increase of porosity of the sintered layer, and the higher strength of sinter charge pellets allows maintaining high gas permeability during sintering, preventing compaction of the charge under the action of vacuum.
The most significant increase in strength characteristics of the sinter charge was observed if surfactant consumption was 1.6 l/h when the number of the fines formed after flushing was reduced from 10.5 – 11.0 % to 8.5 – 9.5 %.
Online since: November 2013
Authors: Paul Kah, Jukka Martikainen, Markku Pirinen, Raimo Suoranta
The excellent properties of UHSS are achieved by employing common alloying elements (carbon, manganese, silicon, nickel, chromium and molybdenum), micro-alloying (Nb, Ti, V, B) and basic metallurgical strengthening mechanisms such as grain refinement, precipitation hardening, solid solution hardening, transformation hardening and dislocation hardening [9,13].
This phenomenon is related to a number of factors such as the hardness and microstructure of the steel, the magnitude of the tensile residual stress, and the level of diffusible hydrogen in the form of atomic hydrogen that is absorbed into the weld pool during welding [19].
A study using continuous and pulsed current in GTAW of a Ni-Cr-Si based medium carbon UHSS [39] shows that the pulsed mode current results in finer grain size, and smaller martensitic platelets coupled with a reduced tendency for segregation.
MR (martensite), parent material [8] In this comparison, continuous current welds exhibited columnar grain morphology whilst pulse current welds had predominantly equiaxed grain morphology.
This phenomenon is related to a number of factors such as the hardness and microstructure of the steel, the magnitude of the tensile residual stress, and the level of diffusible hydrogen in the form of atomic hydrogen that is absorbed into the weld pool during welding [19].
A study using continuous and pulsed current in GTAW of a Ni-Cr-Si based medium carbon UHSS [39] shows that the pulsed mode current results in finer grain size, and smaller martensitic platelets coupled with a reduced tendency for segregation.
MR (martensite), parent material [8] In this comparison, continuous current welds exhibited columnar grain morphology whilst pulse current welds had predominantly equiaxed grain morphology.
Online since: November 2016
Authors: Ping Fu, Xiao Feng Su, Xiao Peng Zhao, Hao Yan
However, as the number of car has been increasing for many years, the passenger tire retreading is urgently needed.
In recent years, with the rapid increase in the number of car, the passenger tire retreading is urgently needed also.
And its main task is to use the ordinary tire grinding machine, profile grinding machine, automatic tire grinding machines and other equipment to abrasion damage, old rubber with much oxidation, and grind out the suitable carcass for prevulcanized tread, the best grinding grain roughness, binding with the renovating glue.
In recent years, with the rapid increase in the number of car, the passenger tire retreading is urgently needed also.
And its main task is to use the ordinary tire grinding machine, profile grinding machine, automatic tire grinding machines and other equipment to abrasion damage, old rubber with much oxidation, and grind out the suitable carcass for prevulcanized tread, the best grinding grain roughness, binding with the renovating glue.
Online since: November 2016
Authors: C.A. León-Patiño, E.A. Aguilar-Reyes, Criseida Ruiz-Aguilar, Ana Edith Higareda-Mendoza
AlamarBlue assays showed that the cell proliferation of MC3T3-E1 preosteoblasts scaffolds were sixfold increase in relation to the number of the initial cells.
The scaffolds with zirconia showed a larger precipitation of HA on their surface than the samples without zirconia; furthermore, bar-like shape HA grains as well as cauliflower-type structure HA can be observed in Fig. 3.
Fu et al. [15]. showed that after 6-day incubation the MC3T3-E1 cells had tripled the initial number.
The scaffolds with zirconia showed a larger precipitation of HA on their surface than the samples without zirconia; furthermore, bar-like shape HA grains as well as cauliflower-type structure HA can be observed in Fig. 3.
Fu et al. [15]. showed that after 6-day incubation the MC3T3-E1 cells had tripled the initial number.
Online since: March 2016
Authors: Xiu Jian Xia, Jin Tang Guo, Shuo Qiong Liu, Jian Zhou Jin, Yong Jin Yu, Ya Kai Feng
Introduction
As we known, the number of deep & ultra deep- and complex- wells is gradually mounting in onshore oilfield exploiting.
From the difference in polymer concentration contained in the initial solution and the filtrate of cement slurries, the adsorbed amount of polymer on cement grain was calculated.
As adding the polymer amount, the API filtration and permeability of set cement deceased obviously while its adsorbed amount on cement grains would gradually increase.
Further adding the polymer, the permeability of set cement, API filtration of cement slurry and adsorbed amount of PADMO-V @NS on cement grains kept fairly consistent.
c b a Fig.9 SEM images of cement filter cake: (a) net, (b) 0.72% PADMO, (c) 0.72% PADMO-V@NS Fig. 10 Comparative consistency curves of slurry with different filtrate reducer in 210℃ (BHCT) Fig. 11 API filtration, permeability and adsorbed amount of PADMO-V@NS on cement grains (T= 80℃, w/c=0.44) Conclusions A novel polymer/silica nanocomposite used as fluid loss control additive was prepared through an in situ free radical copolymerization.
From the difference in polymer concentration contained in the initial solution and the filtrate of cement slurries, the adsorbed amount of polymer on cement grain was calculated.
As adding the polymer amount, the API filtration and permeability of set cement deceased obviously while its adsorbed amount on cement grains would gradually increase.
Further adding the polymer, the permeability of set cement, API filtration of cement slurry and adsorbed amount of PADMO-V @NS on cement grains kept fairly consistent.
c b a Fig.9 SEM images of cement filter cake: (a) net, (b) 0.72% PADMO, (c) 0.72% PADMO-V@NS Fig. 10 Comparative consistency curves of slurry with different filtrate reducer in 210℃ (BHCT) Fig. 11 API filtration, permeability and adsorbed amount of PADMO-V@NS on cement grains (T= 80℃, w/c=0.44) Conclusions A novel polymer/silica nanocomposite used as fluid loss control additive was prepared through an in situ free radical copolymerization.