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Introduction Many studies have been devoted to give a good knowledge of the physical properties of polymeric materials often associated with other environmental stresses [1-3].Under service conditions, these materials are exposed to electrical fields, below the critical level required for rapid failure via an avalanche process.
When the deformation is large, the polymer chains change their configuration, but the electric polarization may be negligibly affected by the large deformation.
This can be done by minimizing the so called correlation factor, C, defined as (7) G and H are the grey scale light intensities corresponding to all the points in the subset, S.
Mayoux, « On the Electrical Properties of Poly (ethylene naphthalate 2,6-dicarboxylate) Biaxially-oriented Films », Polymer International, Vol.46, (1998), pp. 72-76
Schönhals, « Dielectric and dynamic mechanical relaxation behavior of poly(ethylene 2-6 naphthalene dicarboxylate).

Mechanical Properties of Steels.
This circumstance is used to improve the properties of steel after surface plasma hardening.
Lyuftev, Peculiarities of Structuring and Properties Development when Plasma Processing of Carbon Steel, Steel in Translation, 2 (2003) 65-67
Zaimovskiy, Structure and mechanical properties of metals, Metallurgiya, Moscow, 1987
Plokhov, Steel Properties after Controlled Heat Plastic Strengthening when Structuring at macro-, meso- and nanolevels, Izvestiya vuzov, Chernaya Metallurgiya, 4 (2010) 37-40

. % Si to the Zn-6Al-3Mg bath, and the addition of RE effectively decreased the thickness of coating by means of improving the flowing property of the zinc alloy bath.
Zinc bath composition/temperature, immersion velocity/time, substrate composition, air pressure from air knives and running speed of steel-belt are factors that can influence the thickness and corrosion resistance of the hot-dip coating [5-7].
Many researchers have concentrated on studying the corrosion resistance and mechanisms of corrosion resistance of it, but almost all of them did not study the affecting factors that on its thickness.
The decrease of the thickness of the ZAM-S5-R2 and ZAM-S5-R5 coatings could be attributed to the improvement of the flowing property of the zinc alloy bath caused by the addition of RE [14].
The thickness of ZAM-S5 coating could be further decreased by the addition of RE, and which could be attributed to the improvement of the flowing property of the Zn-6Al-3Mg-0.1Si alloy bath after RE was added.

The dip angle of coal seam is 0~3°, with hardness factor f=2.5, and density is 1.28 t/m3.
The method of full-seam mining is adopted in working face, and all caving method is applied for roof controlling. 1—1103 working face; 2—entry protection coal-pillar; 3—headentry of 1103 working face; 4—tailentry of 1105 working face; 5—crossheading Fig.1 Roadway layout in the coal face Theoretical Calculation The design of rational entry protection coal-pillar is a relative complex question, it is affected by many factors such as mining depth, thickness of coal seam, height of entry, mechanical property of coal and rock, and so on [2-4], there is yet not a perfect theory and method on design which can adapt to the different conditions at home and abroad.
Applying the limit equilibrium theory of rock, the width of plastic area caused by gob(x0) is as follow [9]: (6) Where, K—factor of stress concentration, adopting 3.5; P—resistance on coal rib by support, adopting 0.1 MPa; C—cohesion of coal, adopting 1.2 MPa; φ—internal friction angle of coal, adopting 25°; f—friction factor of contact between coal seam and roof or floor, adopting 0.25; ξ—triaxial stress coefficient, .
Similarly, applying the limit equilibrium theory, the width of plastic area caused by entry(x1) is shown as follow [10]: (7) Where, α, k—generalized Mises standard factor, ,.
Conclusions The stability of entry protection coal-pillar in large mining height panel accounts for the support effects of the entry directly, and hence affects the coal mining safety.

Effect of Blockage Ratio on Detonation Flame Acceleration in Pulse Detonation Combustor Using CFD Pinku Debnath 1, a, K M Pandey2,b* 1Research Scholar, Mechanical Engineering Department, NIT Silchar, Assam, INDIA 2Professor, Mechanical Engineering Department, NIT Silchar, Assam, INDIA aer.pinkunits@yahoo.com, bkmpandey2001@yahoo.com, Keywords: Pulse detonation engine, blockage ratio, detonation, diffraction, Computational Fluid Dynamics Abstract.
To prevent the loss and consequently support the DDT the obstacles placed in the tube appear to be an essential factor, which increases the burning rate and facilitates the flame acceleration [15].
Eddy viscosity is the significant factor to analysis the energy losses for detonation flame acceleration.
Higher eddy viscosity of combustible mixture affect is poor combustion efficiency.
The importance of blockage changes with the color plot density of detonation flame accelerating properties (temperature, eddy viscosity, flame velocity and pressure).

Mixing SAC305 with SWCNTs can improve mechanical properties of the alloy composite [3,5].
Wu, study on electronic properties of single-wall carbon nanotubes, Mater.
Tay, Study on the microstructure and mechanical properties of a navel SWCNT-reinforced solder alloy for ultra-fine pitch applications, Thin Solid Films. 504 (2006) 371-378
Zha, Mechanical properties of nickel-coated single-walled carbon nanotubes and their embedded gold matrix composites, Phys.
Hong, Electrical and mechanical properties of carbon nanotube reinforced copper nanocomposites fabricated by electroless deposition process, Mater.

Notations D1 is the nominal diameter of steel tube D is the actual diameter of steel tube t1 is the nominal thickness of steel tube t is actual thickness of steel tube L is the length of specimens Ac is the cross-sectional area of infill concrete As is cross-sectional area of steel tube fy′ is the yield strength of steel bars fy is the yield strength of steel tube θ=fyAs/(fcAc) is the confinement factor Ac1′ is the cross-sectional area outer steel tube fc′ is the compressive strength of concrete outer steel tubes with prisms 150×150×300mm fcu,15 is the compressive strength of concrete with150 mm cubes, where fc′=0.67 fcu,15 fcu is the compressive strength of concrete with100 mm cubes fc is the compressive strength of concrete with prisms 100×100×300mm Ace′ is the cross-sectional area of concrete between stirrups and the steel tubes.
In recent years, Scholars have made systematic studies on the mechanical properties of composite column reinforced with the concrete-filled steel tube[7-8].
A review of available experimental studies shows that the main parameters affecting the ultimate bearing capacity of axially loaded short composition columns reinforced with the high strength concrete filled with steel tubes are: the concretes and their mechanical parameters, such as the strength of concrete including outer and inner steel tube, the steel bar, steel tube and their yield strength of steel bars; the geometrical parameters, such as the steel ratio of steel bar and steel tube, and so on.
Fig 2 Failure mode of the composition columns reinforced with the prefabricated SHSCUS filled with steel tubes On the basis of the experimental phenomena (as shown in figure 2) observed that the damage began firstly from the concrete cover, which is consistent with that of other experts’ result, and the fact that no significant confinement by stirrups on properties of concrete outer the tubes, the authors proposed the assumptions as following: l The ultimate bearing capacity of composition columns reinforced with the super high strength concrete filled with steel tubes is equal to that of reinforced concrete between stirrups and the steel tubes plus that of the super high strength concrete filled with steel tubes.

The development of new composite materials to obtain better mechanical, thermal, and electronic properties depends to a large extent on the metal-ceramic interfaces.
The contact angle, which defines the wettability of a ceramic by a liquid metal, is a basic parameter in obtaining some composite materials, and the value of the work of adhesion affects the mechanical strength of the metal-ceramic interfaces.
Its value affects the bonding strength of the metal-ceramic interfaces and is an important parameter in obtaining some composite materials.
Here, we considered the latter factor for simplicity and calculated ∆G by the Wilson equation and the extended Miedema model [9].
Ye: Handbook of Practical thermochemical properties of inorganic substances(Metallurgical Industry Publications, China 1981).

This phenomenon is affected by not only test variables such as the slip amplitude, applied normal load, etc. but also by service environments (i.e. lubricant conditions).
In an unlubricant condition, the behavior of the wear debris or their layers is considered as a governing factor determining the wear resistance.
However, wear behavior is more sensitive to the material/mechanical properties such as the changed hardness, subsurface deformation in a water lubricant condition [1, 2].
One of the easily applicable methods to decrease the wear damages is to improve the spring shape that could have wear-resistant properties.
However, wear behavior between contacting surfaces is affected by both the contacting spring shape and debris behavior due to the spring characteristics.

It synthesizes the advantages of carbon fibre reinforced plastics and titanium alloy, having good mechanical properties, better impact resistance,and owning the ability of resist erosion from environment.
Ramulu [5] et al. noted that the high temperature of the drilling process affected tool life, and it was easy to produce the burr defect when drilling titanium alloy during the process of drilling composite material and titanium laminated material with high-speed steel (HSS), cobalt high speed steel (HSS-Co), cemented carbide tool.
The tool wear is a major factor which leads to an increase on thrust force, while the high temperature leads to the tool wear increase.
Taking drilling carbon fiber composite materials as an example, if the export appears burr, avulsion, or inner delamination, which will affect the mechanical properties of materials.