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The material properties of recycled concrete were analyzed and some advices about development of recycled concrete in China were presented.
Meanwhile, in the process of civil engineering construction and production of ready-mixed concrete, because of product quality and human factors, also produced a certain amount of waste concrete.
The Material Properties of Recycled Concrete The Water Absorption and Moisture Content of Recycled Concrete.
The Structure Properties of Recycled Concrete.
The Problems in the Using Process of Recycled Concrete Before the recycled aggregate was prepared into recycled concrete, the recycled aggregate would undergo two stages, including the use stage of original building and the crushing stage of waste concrete, these processes would directly lead to a lot of interior microcracks and damage in the recycled aggregate, and affected the mechanical properties of recycled aggregate.

It has been the purpose of the present work to evaluate structures and properties of dissimilar joints between Mg and Al alloys using these two solid state joining processes.
Table 1 represents typical chemical compositions and mechanical properties of alloys used.
Chemical composition and mechanical properties of Al Mg alloys Materials Chemical composition (wt %) Mg Si Cr Mn Cu Zn Fe Al AA1070 0.03 0.2 - 0.03 0.04 0.04 0.25 Bal.
AZ31B-H24 Bal. 0.05 - 0.22 0.05 1.0 0.005 3.0 Materials Mechanical properties Ultimate tensile strength (MPa) Elongation (%) Hardness (Hv) AA1070 70 43 20 AA3003 120 30 35 AA6061-T6 290 25 95 AZ31B-H24 240 15 73 Experimental conditions In MPW, the end of aluminum tube was expand to outer diameter 15 Φ and 15mm width for lap joint.
The maximum tensile strength of 179 MPa, which was about 80 % of the Mg base metal tensile strength, has been obtained, indicating that tensile properties and fracture locations of the joints were affected by the formation of intermetallic compounds References [1] Michael M.Avedesian, ASM Specialty Handbook, Magnesium and Magnesium Alloys,ASM international. 16-21 (1999) [2] J.C.

Factors affecting coal seam water effects are follows: wetting properties of liquids, coal gas pressure and internal gas pressure on coal, cracks and pores of the degree of development and injection parameters.
Electrostatic precipitator dust removal efficiency is high, but the installation requirements are strict, need to consider the dust properties, installation conditions and economic cost.
The main factors of affecting the efficiency of ventilation dusting are the properties of wind speed, mineral dust density, particle size and so on.
Conclusion In view of the relationship between numerous dust control technology and the physicochemical properties of dust, the paper does testing and analysis of dust around the working face before making dustproof job.
It is necessary to test and analyze the nature of true density, specific surface area, dispersion, surface tension, contact Angle, the optical properties, wettability and charged, etc.

Due to positive response to age hardening treatment there is an improvement in the mechanical properties of Al6061 alloy & its hybrid composite.
Poovazhagan et al [4] reported that addition of SiC & B4C resulted in increase in hardness & better tensile properties.
This results in large internal stresses and mismatch strain that affect the microstructure and mechanical properties of the composites.
· Al6061 alloy and Al6061-B4C-SiC hybrid composites positively responds to age hardening treatment with considerable improvement in mechanical properties
· Al6061-3%B4C-3%SiC hybrid composite exhibits superior mechanical properties in comparison with Al6061 alloy, Al6061-1%B4C-5%SiC and Al6061-2%B4C-4%SiC composites.

Wan 1, b , D.J.Hu 1, c 1School of Mechanical and Power Engineering, Shanghai Jiaotong University, Shanghai 200030, P.R.
It shows that normalized wear rate is mainly determined by fractal dimension besides the material properties and an optimal fractal dimension existed for the engineering surface is affected by the plastic index, normalized true contact area and scale coefficient.
However, these parameters do not consider the functional properties of the surface, the effect of surface topography change on the frictional behavior of the roller and the steel sheet can be represented by the parameters.
The premise of using fractal is that the surface has fractal properties.
The analysis of the effect of surface topography on the wear rate of the roller with fractal geometry model for wear prediction shows optimal fractal dimension of roller surface is affected by the normalized contact area and scale coefficient and material property, and normalized wear rate is mainly determined by fractal dimension.

Twin boundaries act as obstacles for dislocation slip, and thus, further reduce the effective grain size, which affects the fatigue response as well.
The mechanical properties are summarized in the table inset in Fig. 1.
The differences in the mechanical properties of the fine and coarse grained condition are a direct result of dislocation motion on specific slip systems and mechanically-induced twinning.
This is attributed to the high ductility of the coarse grained condition, which is a dominant factor in the LCF regime.
Barbier, High manganese austenitic twinning induced plasticity steels: A review of the microstructure properties relationships, Curr Opin Solid State Mater Sci, 15 (2011) 141-168. [2] G.

Measured values can be affected i.a. by the energy of random effects or other, less important components of the signal.
In the paper the author describes the method of minimization of the impact of disturbances on signals being analysed using basic properties of autocorrelation function.
These are not the only properties of these functions.
In addition, this function value depends on several other factors such as influences of random and non-linear effects.
However, the effectiveness of this analysis for real systems can be only obtained when properties of these functions are combined together.

Dielectric Tunable Properties of Ba0.6Sr0.4TiO3 Thin Films with and without LSCO Buffer Layer Xiaohua Suna, Ping Feng, Jun Zou, Min Wu School of Mechanical and Material Engineering, China Three Gorges University, Yichang 443002, China.
a mksxh@yahoo.com.cn Keywords: BST thin films, LSCO buffer layer, PLD, dielectric tunable properties.
The influence of LSCO buffer layer on the microstructure, dielectric and tunable properties of BST thin films were analyzed.
It is found that the dielectric constants and dissipation factors of the BST films with and without LSCO buffer layer are not strongly dependent on the frequency in this frequency range.
However, there are some differences in the dielectric properties between two films.

The Optimization Design of Vacuum Chamber in Vacuum Electron Beam Welding Machine Weiwei Yue1, a,Yimei Song1,b ,Dongbo Zhou 1,c ,Cai Liao1,d and Danping Liu1,e 1 School of Mechanical and Electrical Engineering, Guilin University of Electronic Technology, Guilin, 541004, China agood8593144@yahoo.cn, bsongym@guet.edu.cn, czdb799@126.com, dliaocai2007@163.com, edanping0403@163.com Keywords: Vacuum chamber, Computer simulation, Optimization.
Chamber deformation in vacuum electron beam welding machine directly affects the processing precision of whole equipment.In order to further improve performance of the welding machine,by the use of the computer simulation software, the Chamber structure in some type of vacuum electron beam welding machine,was optimized designed.
Thus, the deformation of vacuum chamer will affect the kinematic accuracy of moving parts and electron gun, and directly cause the bad welding quality.
Some unimportance factors could be gnored,and quote some assumptions, Kirchhoff's hypothesis.
Looking up the related manual about mechanical design,we can get material property parameters.

The effect of Cu, Ni, Fe, Mn on the mechanical properties of Al-Si alloy by orthogonal experiment methodwas investigated in this paper.
Table 2 Room and high temperature tensile strength orthogonal test results No. ωB Room temperature High temperature（300℃） Cu Ni Mn Fe σb/MPa σb/MPa 1 0.5 0.7 0.2 0.3 215 190 2 0.5 1.5 0.5 0.6 196 177 3 0.5 2.3 0.8 0.9 277 175.5 4 1 0.7 0.5 0.9 249 212 5 1 1.5 0.8 0.3 196 204 6 1 2.3 0.2 0.6 202 193 7 1.5 0.7 0.8 0.6 211 178 8 1.5 1.5 0.2 0.9 196 170 9 1.5 2.3 0.5 0.3 231 201 Table 3 Tensile strength range analysis Range Hightemperature strength Roomtemperature strength Cu Ni Mn Fe Cu Ni Mn Fe KⅠ 180.83 193.30 184.33 198.33 229.33 225.00 204.33 214.00 KⅡ 203.00 183.70 196.67 182.67 215.67 196.00 225.33 203.00 KⅢ 183.00 189.80 185.83 185.83 212.67 236.70 228.00 240.67 R 22.17 9.60 12.34 15.66 16.66 40.70 24.00 37.67 Factors order 1 4 3 2 4 1 3 2 As can be seen from Table 3, the greatest impact of alloy elements on the tensile strength at room temperature is Ni, followed by the Fe, Mn, Cu; Cu is the most affected element on high temperature tensile strength
This phase causes severely matrix fragment, thus reduces the mechanical properties of the Al-Si alloy and is regarded as harmful with restriction.
This conversion further improves the morphology of Fe phase, reduces the stress concentration of herringbone Fe phase, and improve the mechanical properties of the alloy.
Effects of Cu on microstructure and mechanical properties in Al-Si-Cu-Ni alloy.Special Casting & Nonferrous Alloys，2010,30（9）,ppC871-873.