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Introduction Dust explosion (or detonation) hazard has been inherent part in modern industrial activities, such as in coal mine, metal powder applications and grain processing plants.
Numerical Modeling The mixtures consisting of solid particles with small diameter and spherical shape suspended in gaseous situations are usually modeled using the continuum media theory when the number of particles is large enough.
Np, and are the number density, density and diameter of the particle, respectively. dp0 is the initial particle diameter.
Re is the relative Reynolds number. , and are the burning rate constant, the surface reaction rate and the activity energy, which should be considered experientially.

The number of pulses of the plasma arc discharge was 3000 at frequency of 3 Hz.
The kinetic dependences of the friction coefficient of µ on the number of friction cycles N for multilayer coatings of Me1/a-С/Me2 Me1/a-С/Me2 type for the initial fresh coatings obtained were analyzed as well as after annealing at the annealing temperature of 200 and 400 °C.
At temperature annealing of Ti/a-С/Ti coatings, solid phases of TiN, TiC and TiCN, and TiхОу oxides are formed with the formation of crystalline grains.
This increases their ordering and stimulates the formation of carbide carbon-titanium bonds (for Ti/a-С/Ti coatings) or the increase in the number of Сsp2 clusters in the case of Cu/a-С/Cu.

This layer has a smaller surface area, possibly reducing the amount of light absorbed and the number of electrons and holes generated.
Conversely, the electrode with smaller particles has a larger surface area and a greater number of contact points between sintered particles, allowing for greater dye adsorption.
This layer exhibits a larger number of grain boundaries that electrons need to pass through, which results in a higher probability of electron trapping [7–9].

Its crushing value for 7.8%, continuous graded aggregate well grained, specified （JTG F30-2003）. 2 Method of test 2.1 mix of cement concrete The mix of the cement concrete is specified the heavy trafficked road design, e.g the flexural strength is 5.0MPa.
Table 3 The mixes of the concretes and the strength tested（kg/m3） Number cement Fly-ash sand Crushed-rock water admixture nano 28dflexural （MPa） PC 360 0 650 1270 151 3.6 0 5.93 PCF 306 75.6 513 1270 151 3.6 0 5.88 NSC1 304.5 75.6 513 1270 151 3.6 1.5 6.08 NSC2 302.9 75.6 513 1270 151 3.7 3.1 6.49 NSC3 301.4 75.6 513 1270 151 3.8 4.6 6.32 NSC4 299.9 75.6 513 1270 151 3.9 6.1 5.84 The test results showed above, the flexural strength will be increased in concrete added with nano-SiO2, known from the table 1, there is a peak in the series of flexural strength, when the content of nano-SiO2 is big enough, the flexural strength be decreased.
All samples be dried, then signed and weighed and, then be put on the same shelf of bars in according to the signed number.
Table 4 Rate of the Concrete Strength Lost After a Freezing and Thawing for One Cyclical Time Signed number 50times strength contrasted （MPa） Strength tested after 50times （MPa） rate of the concrete strength lost（%） 100times strength contrasted（MPa） Strength tested after 50times100（MPa） rate of the concrete strength lost（%） PC 60.2 56.5 6.2 62.8 54.2 13.7 PCF 58.4 55.6 4.8 63.5 56.7 10.7 NSC1 64.3 63.3 1.6 68.7 65.5 4.6 NSC2 67.6 66.7 1.4 70.0 67.3 3.8 NSC3 66.2 65.5 1.0 69.3 67.2 3.1 NSC4 57.5 56.8 1.2 67.5 65.3 3.3 Table1 Influence of Resistance to Frost of Cement Concrete With SiO2 From Table 4 and Figure 1, frost-resistance of the cement concrete substituted with fly-ash and nano-SiO2 as admixture will be increased higher accordingly than the resistance to freezing of the cement concrete substituted with fly-ash.

The base powder used is direct metal 50,which is a bronze based metal powder with a grain size of 50 microns and a composition of Copper 22-90%, Tin 2-10%, Nickel 10-70%, Phosphorous 3-6 %.
Taguchi approach was adopted to reduce the number of trials of the design of experiments in which multiple factors are involved.
The DMLS process based metallic components are expensive and time consuming process, therefore we consider the orthogonal array with minimum number of trials.
The Brinell harness number is calculated by dividing the load applied by the surface area of the indentation.

A number of studies have been conducted in WLAN location method [5].
Consider FPA first; it can be observed that the average errors of location determination are 9.97 meters, 9.92 meters, 11.02 meters, and 12.70 meters when the different numbers of the nearest locations (k) are from 1 to 4.
Therefore, we set the number of the nearest locations (k) as 2 and apply FPA in CGS.
Strivastava: Dynamic Fine-Grained Localization in Ad-Hoc Networks of Sensors.

Rotations can be caused by: • The desire to form low energy grain boundaries in the interparticle contact zones [7], • Tensions [8] caused by inhomogeneous particle center approach due to different particle sizes and inhomogeneous packings and • Asymmetric [8] tensions inflicted by asymmetric sintering necks.
The numbers of new and broken contacts were determined.
In addition to the directly measured densification, the coordination number increases over the entire sintering process.
It increases to values above 1.5 ° for regions with high density as in these regions the number of surface points applicable for the fit of the sphere model is much reduced.

But the tailing grade was generally high,fine grained useful minerals in a serious loss, low metal recovery.
The working principle of flotation column is that the upper ore feeding tube feed pulp, uniformly flow through the flotation column, compressed air in inflatable chamber that is the lower end of the columnar body through a vertical air pipe filling column, formating a large number of small bubbles uniformly distributed across the entire cross section, pulp under the action of gravity falling slowly, air bubbles from bottom to top rising slowly, and constantly meet the useful minerals pulp in the column.
In convection, due to the pharmacy's role, the selected minerals attached to the rising bubbles to the surface, formating the mineralized foam layer in the column upper, overflow the spill to concentrate tank, other minerals (usually gangue or non ore ) discharge from the lower end tailings discharge tube. the upper ore feeding tube in the flotation column has a variety of tube depth, the number of occurrences are depending on the size of the column diameter.
The ore in three village which is belonged to Luoyang Luanchuan Molybdenum Group Limited by Share Ltd are mainly skarn type, molybdenum and tungsten ore deposit belongs to the symbiosis, molybdenum is easy to choose, tungsten ore has low grade, is hard to choose, using CCF column flotation to recovery low grade scheelite in molybdenum tailings, compared with the pneumatic flotation machine, greatly reducing the number of operations, through once roughing and once scavenging to instead of once roughing three scavenging and three preconcentration, decreasing two times of scavenging and three preconcentration, greatly improve the production index, increase more than 20% in the recovery, the CCF column flotation equipment with high efficiency and energy saving, power consumption is about 8.5kW per hour and per ton of ore, lower 43.33% than the inflatable flotation machine power consumption.

The number of pieces increases obviously.
The unhydrated fly ash presents grain shape and covered by the hydration products.
Wide and a large number of cracks in the aggregates are observed.
Further more, a large number of pores are appeared in the surface of matrix, and the size of the pores is large.

This heat input is responsible for a number of defects in the workpiece like metallurgical alterations, microcracks and residual stresses [6], creating the so-called heat affected zones.
The heat produced by the interaction of the abrasive grains of the grinding wheel and the workpiece is represented by a heat source, computed by Jaeger model [6].
For a specific flow rate, the velocity of nanofluid can be computed and given its properties, i.e. kinematic viscosity and density, the calculation of heat transfer coefficient h is performed after dimensionless numbers Reynolds (Re), Prandtl (Pr) and Nusselt (Nu) are determined for each case.
Nusselt number in the case of nanofluids based on Al2O3 can be computed using the formula proposed by Minea [14]: (4) where φ is the volume fraction of particles.