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The plane distribution of PAHs in soil is mainly controlled by wind direction and slope, vertical distribution is controlled by its solubility in water and soil properties.Many kinds of PAHs in soils out of limit, which is poor soil.The 6 kinds of heavy ring PAHs which is carcinogenic is distributed in 5~15 cm of the topsoil.
They had been being of soil environmental pollution problems of the system due to some of them proved to be mutagenic, carcinogenic and teratogenic, their bioaccumulation potential in the tissues of animals and humans throuth the food chain, and their toxic properties for human and wildlife[1].
The purpose of sampling points’ layout principle is to be able to find out the content of pollution factors in different distance apart from the coal waste rock dumps in different depths of soil.
Table 2 Toxicity equivalence factors of 16 PAHs PAHs TEFs PAHs TEFs Nap 0.001 Baa 0.1 Ane 0.001 Chr 0.001 Any 0.001 Bbf 0.1 Fle 0.001 Bkf 0.1 Phe 0.001 Bap 1 Ant 0.01 Daa 1 fla 0.001 Bgp 0.01 Pyr 0.001 Ilp 0.1 TTEC= In the formula: MSCi is the measured concentration of i , TEFi is the toxicityequivalent factor of i.
The vertical distributions is controlled by its water solubility and soil properties.

In this paper, sliding friction model under electric current was established according to the friction pair of third rail and collector shoe used in subway third rail traction system, and surface sliding contact under electric current was simulated by ANSYS, then the temperature changing property of contact zone was revealed with the coupling of friction thermal and contact resistor thermal, and the main factors that influence the temperature changing of the friction pairs were studied.
The thermal-mechanical coupling element plane13 was used for the three samples.
The properties of three materials were in Tab.1.
As for area-area friction pair, the total heat flux which sourced from mechanical friction can be calculated by the formula as follows: (2) where is energy conversion factor(defaulting as 1) in frictional heating; is equivalent friction stress; is relative sliding speed rate of the friction pair.
(2) In the process of the coupling of mechanical friction thermal and contact resistor thermal in friction and wear with electric current, the coupled temperature are distinctly affected by electric current, sliding velocity, sliding displacement under the constant normal force.

As an example of collapsible loess foundation treatment project in central and southern shanxi tunnels five railway culvert, the collapsible loess and harm of engineering properties, this paper introduces the construction method by cement-soil compaction pile to reinforce the foundation in order to ensure the quality and effect of the overloaded railway foundation.
All those will seriously affect the normal operation and safety of train.
The Reinforcement Principle for Compaction Pile The root reason of foundation treatment for collapsible loess is to destroy the macroporous structure and to improve the engineering properties of soil in order to eliminate or reduce the collapsibility and deformation of foundation.
The reinforcement principle for using soil compaction pile to deal with collapsible loess foundation is to drill holes and compact cement by layers then resulting in the lateral compression pressure to compact the soil between piles and improving engineering geological properties of the foundation.
Hole mechanical surface should have obvious penetration tag in order to control depth of hole.

Aluminium reinforced with SiC, Al2O3 and B4C etc. possesses an attractive combination of properties such as high wear resistance, high strength to weight ratio and high specific stiffness.
In the view of physical properties, B4C has less density than that of SiC and Al2O3, which makes it an attractive reinforcement for aluminium and its alloys for light weight applications.
It is used as automobile products (ex. brake pads, engine piston) as a result of these excellent properties.
Rama rao et al., studied the fabrication and mechanical properties of aluminum-boron carbide composites.
[5] Y.Sahin, Preparation and some properties of SiC particle reinforced aluminium alloy composites, Materials & Design, 24 (2003) 671-679

Structure of the beam So far, neither the entirely appropriate element type exists which can be used to simulate magnetorheological fluid behavior directly in ANSYS, nor a completely suitable material model conforms to the rheological characteristics and mechanical properties of MR fluid.
It was assumed that the electromagnet does not change its position and affects the MR fluid in the position of  mm.
In this range the properties of the fluid change along with the various intensity of magnetic field H generated by the electromagnets: kp(H), cp(H).
The peaks of the curves, representing the response amplitudes at resonance frequencies, becomes flatter due to the higher loss factors.
Wu: Finite element analysis of a simply supported MR fluid sandwich beam based on ANSYS, Applied Mechanics and Materials, 94-96, 902-908 (2011) [15] MRF-132DG Magneto-Rheological Fluid Typical Properties, Lord Inc. http://www.lord.com/ [16] ANSYS help, ANSYS Inc

.% NaCl Solution Seong-Cheol Jang1,a, Dong-Ho Bae2,b and Gyou-Young Lee1,c 1 Student, Graduate School, Mechanical Engineering Department, Sungkyunkwan University, 300 Chunchun-dong, Jangan-gu, Suwon, Kyunggi-do 440-746, Korea. 2 Corresponding Author, Professor, School of Mechanical Engineering, Sungkyunkwan University, 300 Chunchun-dong, Jangan-gu, Suwon, Kyunggi-do 440-746, Korea.
From these efforts, the advanced technologies and methodologies to obtain information on their actual degradation as well as life prediction under the corrosive environments and mechanical condition have been developed [1-3].
Its chemical composition and mechanical properties are illustrated in Table 1.
Since the asperity and oily particles on the surface of the specimen affect corrosion reaction, after polishing the surface of every specimen, then cleaned with the ultrasound washer.
The reason why the crack growth rates under corrosion environment is larger than those of in air is due to the fact that corrosion active factor like Cl- made cathodic dissolution at the crack tip and acted as a factor accelerating crack growth rate [9.10]

Smith 1,c 1 Department of Mechanical Engineering, Imperial College London, Exhibition Road, London, SW7 2BX, UK 2 Steel Research Laboratories, Nippon Steel Corporation, 20-1 Shintomi, Futtsu, Chiba, 293-8511, Japan a kayamori.yoichi@nsc.co.jp, bs.crofton@imperial.ac.uk, croderick.smith@imperial.ac.uk Keywords: Ductile fracture; line pipe; equivalent plastic strain; stress triaxiality; CTOA; Global constraint factor Abstract.
In addition, ductile crack rapid propagation was assessed by the relationship between the critical CTOA and the global constraint factor, where the critical CTOA remained almost constant because of high constraint.
Introduction The burst property prediction of high-pressure gas pipelines made from recent high-grade line pipes such as the API Standard 5L X80 through X100 should be extremely reliable because such bursting could lead to extremely dangerous situation, combined with the high crack-driving force of the pipelines under high-pressure.
The authors [4, 5] showed that crack velocity slightly affected αg and αg influenced the constant CTOA.
Vol.70 Issues 3-4 (2003), p.567-577. 0.8 0.9 1 1.1 1.2 0 100 200 300 400 500 600 Global constraint factor, g Crack velocity, dc/dt (m/s)In the starter pipe In the T4 prop. pipe α 388m/s 125m/s 0.953 1.01 Fig. 4 Relationships between the crack velocity and the global constraint factor.

Summarizing the numerous experimental data on the study of the causes that lead to the appearance of cold cracks during laser processing, it is necessary to distinguish the main factors: structural, hydrogen, force, temperature and scale.
Of the above-mentioned main factors that cause the occurrence of the phenomenon of delayed destruction, the effects of residual austenite and diffusion-mobile hydrogen are practically not studied under laser quenching conditions.
The mechanism of the effect of hydrogen on the mechanical properties of steels is explained by the following provisions: the accumulation of molecular hydrogen in micro-voids, an increase in the content of atomic hydrogen in places of concentration of tensile stresses, a decrease in the free surface energy during the adsorption of hydrogen atoms on internal defects of steel [14].
of the processed materials and provide the properties of the surface layers of products necessary for various operating conditions.
Influence of hydrogen on the structure and properties of iron-carbon alloys, Mashinostroenie, Moscow, 1982 [11] Fedotov S.

Shield tunnel floating involves many factors,which not only consist the problems of tunnel design itself,such as tunnel linear,the thickness of overburden soil,formation characteristics and surrounding environment.But also consist the problems of construction technology,such as the control of tunnel axis,construction parameters and grouting materials properties etc[2,3,4].
Shield machine works under shallow covering in the bottom of the river, unbalanced forces of the tunnel will cause tunnel floating,and it is difficult to control the tunnel axis.what’s more,it is easy to cause flooding accident due to construction parameters control，which affects construction safety and tunnel forming quality[5].
Figure 1 Plane relation with shield tunnel and Tangjia river The outside diameter of shield tunnel is 6.2m,the inside diameter is 5.5m,the segment lining thickness is 0.35m,the segment ring width is 1.2m,staggered assembling,bolted joint.Shield is mainly through silty sands.Soil main physical and mechanical indexes are shown in Table 1.
Table 1 Soil main physical and mechanical indexes Soil Name Unit Weight （kN/m3） Compression Modulus （MPa） Cohesive Force （kPa） Internal Friction Angle （°） ②1clayey silt with silty clay 18.6 7.9 12 28 ③1sandy silt 19.0 14.38 5.0 31.5 ③2silt 19.0 13.08 1.0 32.5 Calculation of the minimum thickness of overburden soil Shield tunnel across the river and other shallow covering should meet the requirements of the minimum thickness of overburden soil.Simplified calculation analysis method is usually used to calculate the minimum thickness of overburden soil by analyzing force balance of segments buoyancy,the weight of upper soil column and segments weight[5].The minimum thickness of overburden soil calculation diagram is shown in figure 2.
Besides taking anti-floating reinforcement measures, shield construction parameters control is an important guarantee to ensure construction safety.Soil chamber pressure control directly affect the stability of excavation face;grouting pressure size, distribution patterns and slurry characteristics directly affect the size of buoyancy on the tunnel[9,10].Therefore, soil chamber pressure and grouting pressure should be controlled strictly in this project

In this paper, the machining strategies for fabrication of die assembly with typical shaped cavity using EDM were discussed, according to the different cavity structures, the best machining strategies were proposed Introduction With the development of material science and industry progress, a large number of high strength, high hardness, high toughness, high brittleness, high temperature and other special properties of the mold material have been applied more and more widely.
Adaptive control is more or less a feedback loop; as information is fed to the controller from the workpiece, the controller is able to change its inputs thus affecting the workpiece.
As the spark melts the workpiece, so too is the tool electrode affected.
Tool electrode a) Rough machining b) Semi-finishing c) Finishing machining d) Schematic plan of machining Fig.6 Machining strategy of fabrication Conclusions The strategies for fabrication of die assembly with typical shaped cavity by using electrical discharge machining are researched, and the following conclusions are drawn. 1) Electrical discharge machining (EDM) method is very suitable for fabrication of hard material with the typical shaped cavity such as deep and narrow slot or freedom surface. 2) The tool electrode wear, especially the corner wear is one of the main factors influence the machining accuracy of machining die assembly using EDM method. 3) Several machining strategies for fabrication of die assembly with typical shaped cavity are discussed.
[4] Zhao Wei, Ren Yanhua, Ren Zhonggen, et al., “Research on the movment law of charged particle in the channel of EDM,” Mechanical Science and Technology, vol. 20(5), pp 762-763