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Hand held mechanical tools and awkward posture are low back pain risk factors [9].
In a farm the most important sources of mechanical vibrations are the electro-mechanical tools.
Its mechanical properties can be easily modified so frequent exposure to HAV or WBV can lead to permanent health effects.
Spine disorders can be the results of vibration exposures combined with other factors.
Gharpuray, Can variations in intervertebral disc height affect the mechanical function of the disc?

The growth of microalgae are affected by many factors, such as N and P concentration, pH, light intensity, temperature and aeration [4, 5].
The results indicated that the length of the exponential period was affected by wastewater concentration.
The interaction of the two algae species in mixed algae culture was also affected by the initial pH.
Lan Enhancement of lipid production using biochemical, genetic and transcription factor engineering approaches (Journal of Biotechnology, 2009)
Optical properties of Nannochloropsis sp and their application to remote estimation of cell mass (Biotechnol Bioeng, 2000)

There are many factors which influence the rate of spalling.
The size of pores depends on chemical and mechanical reactions.
The bigger pores and cracks could affect also the strength of the material.
The combination of chemical and mechanical changes in structure causes collapses and destructions of concrete microstructure.
Schwesinger, High performance concrete: material properties and design: proceedings of the Fourth Weimar Workshop on High Performance Concrete: Material Properties and Design held at Hochschule für Architektur und Bauwesen (HAB) Weimar, Germany, October 4th and 5th 1995.

Unfortunately these substances lack the necessary mechanical qualities, whereas the metals fail to fulfill the chemical and biological requirements.
The in vivo performance of such coatings depends on a large variety of factors such as chemical composition, crystallinity, phase purity, and resorption behavior.
However, thermally-sprayed hydroxyapatite coatings are affected by some disadvantages such as disintegration of the ceramic layer and detached ceramic fragments.
Cell number on materials 1-5 after 3, 7, 14 and 21 days Conclusion Bioactive ceramics are used as coatings on metallic implants, to combine the favourable biologic response of bioceramics with the stronger mechanical properties of metal prostheses.
Effect of the suspension composition on the microstructural properties of high velocity suspension flame sprayed (HVSFS) Al2O3 coatings.

So this paper mainly studies the influence of above factors to the joint rock deformation and strength character.
Brief of RFPA 2D As the rock material is in fact non-homogeneous, the two-dimensional Rock Failure Process Analysis code (RFPA 2D ) assumes that the rock mass is composed of many mesoelement whose material properties are specified according to the Weibull distribution.
Calculation models and mechanical parameters.
The analysis provides theoretical basis to evaluate the joint rock strength properties and engineering stability based on geological sketch data, such as joint rose diagram.
Goodman, "The mechanical property of joints", In Proc. 3rd Cong ISRM, Denver, Part A, 1974, p. 127-140

Introduction In aerospace, with such working conditions as high speed, heavy load, high temperature, cryogenic environment and alternating temperature, surface failure of the tribo-part is one of the most important factors that affect the reliability of the whole work system.
Mechanical structure and lubricating system.
Fig.1(a) shows mechanical structure of the test rig, Fig.1(b) shows the mounting arrangement of the tested pieces.
Fig.3 Scheme diagram of software Several experimental results of the elliptical point contact Tribological properties of the material in room temperature.
It indicates that compared with the contact stress, the increase of sliding speed is the prior factor of surface damage generation.

Then, with mixture of fiber reinforcement polymer and concrete will improve mechanical properties.
With using finite element method can predict new mechanical properties.
In the development of confined concrete, there are several factors can be considered in investigation such as cross section shape [13,14], material chosen for confined jacket [6,15,16], and cross-sectional aspect ratios [17] to optimized mechanical strength in confining system.
This paper proposes confined concrete model by existing short steel 4340 fiber as reinforcement on predicting mechanical properties for both compressive and flexural performance.
Material properties.

There exist many dangerous and harmful factors in by-product steel gas power generation process and which easily caused casualties and the pollution of the environment.
(2)The determination compensation factors of safety measure.
The safety measure compensation factors were analyzed according to the specific circumstances of process unit.
Table 1 Fire, explosion, toxicity index on combustion unit Project Combustion Main material CO 1．material factors（B） 6.0 2. special material hazard range of hazard factors hazard factors A mix and dispersion characteristics -60～60 -20 B sensitivity of catch fire -75～150 150 C explosion properties of gas 150 150 special material hazard calculation（M） 280 3. general process hazard A use and only Physical change 10～50 10 B container of may transport 10-100 25 general process hazard calculation（P） 35 4. special process hazard A high pressure 0～150 75 B high temperature 0-40 25 C joint and gasket leakage 0-60 20 D explosion hazard above average 40-100 100 E static electricity hazard 0-200 35 special process hazard calculation（S） 255 5. quantity hazard factor of quantity Q 1～1000 100 6．hazard of configure A structure design 0～200 20 B the domino effect 0-250 10 C others 0-250 25 hazard of configure calculation（L） 55 7．toxicity hazard A TLV value 0-300 130 B material type
Therefore, various factors and logical relationship of boiler explosion were analyzed by fault tree analysis [7].

In the as-welded test specimen, two peak transverse residual stresses (sx) were located on either side of the weld centerline in the region roughly between the weld nugget and the thermal-mechanical affected zone (TMAZ).
This area of the weld will be relatively ineffective in inhibiting dislocation motion and the strain localization in the softened area of the weld will result in degradation in the mechanical properties [4].
During the fatigue testing, it was observed that hammer peening the plates reduced the tensile residual stresses in the lap joints and increased the fatigue life by a factor of 10.
Sandtrom, Fatigue properties of friction stir overlap welds, International Journal of Fatigue 68 (2005) 456-468
Hatamleh, The Effects of Laser Peening and Shot Peening on Mechanical Properties in Friction Stir Welded 7075-T7351 Aluminum, ASM International 17 (2007) 688-694

The results show that: there are great differences between the resonance frequencies of two shells but the linear harmonic response properties are basically the same; the dynamic characteristics of these two shells are greatly different under harmonic loads or seismic loads, and the dynamics characteristics are greatly influenced by the viscous properties of the material itself.
Meanwhile, in high temperature or explosive environment, and with the impact load, the viscosity of steel material is enhanced highly and plays a dominating factor of the whole mechanical properties of the structures.
To investigate how the material viscosity affects the vibration characteristics of long-span space structure under harmonic loads or seismic loads comparative analyses of two aluminum alloy single-layer spherical shells with the same span, same rise-span ratios and same bars, but one is elastic and the other is visco-elastic, are carried out.
Obviously, the vibration characteristics of shells are apparently affected by the viscosity of material.
Acknowledgment This work has been supported by Guangdong Province Science and Technology Plan Project (2010B010800004; 2011A080802010) and the Opening Fund of Laboratory for Mechanical Behaviors and Design of Materials, Chinese Academy of Sciences (LMBD-2011-2).