Velocity range

For every value of the velocity v, the velocity ranges dv, 5v in the above expression are only over that range of velocities v, v, such that particles with velocity in the range 8v about v are produced in the (v, v, )-collisions. If we now use the equalities, equation (A3.1.39), as well as the fact that g = g, we can write... 

In commercial practice, powdered explosives on an ammonium nitrate basis are used in most cases. Typical detonation velocities are between 1800 and 3500 m/s depending on the metal system to be bonded. The lower detonation velocity range is preferred for many metal systems in order to minimize the quantity of solidified melt associated with the bond-zone waves (12). In addition, subsonic detonation velocity explosives are required for the parallel cladding technique in order to avoid attached shock waves in the coUision region, which preclude formation of a good bond. 

Specific Commercial Rotational Viscometers. Information on selected commercial rotational viscometers can be found ia Table 7. The ATS RheoSystems Stresstech rheometer is an iastmment that combines controlled stress as well as controlled strain (shear rate) and oscillatory measurements. It has a torque range of 10 to 50 mN-m, an angular velocity range of 0 to 300 rad/s, and a frequency range of seven decades. Operation and temperature programming (—30 to 150°C higher temperatures optional) are computer controlled. 

H) was determined for each solute, in each solvent mixture, for 10 different linear velocities ranging from 0.02 cm/sec. to 0.6 cm/sec. Three measurements were taken at each velocity, which produced a minimum of 180 values of (H) for each solute. Each data set was then fitted to each dispersion equation and the respective constants... 

Piping systems should be designed for an economic flow velocity. For relatively clean fluids, a recommended velocity range where minimum corrosion can be expected is 2 to 10 fps. If piping bores exist, maximum fluid velocities may have a mean velocity of 3 fps for a 3/8-in. bore to 10 fps for an 8-in.-diameter bore. Higher flow velocities are not uncommon in situations that require uniform, constant oxygen supply to form protective films on active/passive metals. 

A calibration facility must produce the desired velocity range for the meter to be calibrated. The air temperature should be kept constant over the test to ensure constant density. For thermal anemometers, velocity calibration only is not sufficient. They should also be checked for temperature compensation. In the case of omnidirectional probes, sensitivity to flow direction should be tested. In the case of low-speed (thermal) anemometers, their self-convection error should be measured, and, for instruments measuring flow fluctuation (turbulence), dynamic characteristics testing should be carried out as well. ... 

Normally, catalytic reformers operate at approximately 500-525°C and 100-300 psig, and a liquid hourly space velocity range of 2-4 hr" Liquid hourly space velocity (LHSV) is an important operation parameter expressed as the volume of hydrocarbon feed per hour per unit volume of the catalyst. Operating at lower LHSV gives the feed more contact with the catalyst. 

Coppock and Meiklejohn (C9) determined liquid mass-transfer coefficients for the absorption of oxygen in water. The value of k, was observed to vary markedly with variations of bubble velocity, from 0.028 to 0.055 cm/sec for a velocity range from 22 to 28 cm/sec. These results appear to be in general agreement with the results obtained by Datta et al. (D2) and by Guyer and Pfister (G9) for the absorption of carbon dioxide by water. 

More recently, experimental studies have been carried out using a similar device but with an annular external hot coflow of burned gases that allowed one to operate within a much larger velocity range. Chen et al. [26] and more recently Chen and Bilger [27,28] have studied the perturbations that the smallest scales of turbulence can impose to the local flamelet structures. Those studies are of paramount importance, first because they have allowed to get deeper insights into the local structure... 

Fig. 3.2 Triangular velocity reference signal top) and drive error signal bottom) of a Mossbauer drive operating in constant acceleration mode. The error signal is taken from the monitor output F of the drive control unit (see Fig. 3.1). Usually it is internally amplified by a factor of 100. Here, the deviations, including hum, are at the 2%o level of the reference. The peaks at the turning points of the triangle are due to ringing of the mechanical component, induced by the sudden change in acceleration (there should be no resonance line at the extremes of the velocity range)...

The calibration procedure is sufficiently accurate for Doppler velocities in the regime 0 to 10 mm s beyond this range, laser calibration is more suitable. Calibration with ot-iron, as described, can also be used for Mossbauer measurements with other isotopes, e.g., Ni, Au, and Ir, for which suitable standard absorbers are not available (provided that the Doppler velocity range of interest is not significantly greater than 10 mm s ). This, of course, requires that the spectrometer is temporarily equipped with a Co source and an a-iron absorber. 

Griesinger et al. [56] recorded Zn Mossbauer spectra with sources of Zn diffused into ZnO, ZnS (both wurtzite and sphalerite), ZnSe, ZnTe, and Cu, and an enriched ZnO absorber. The isomer shifts extracted from their spectra cover a velocity range of 112 pm s and were found to follow linearly the lattice spacing parameter where p and Mav are the host density and average... 

The typical observable velocity range is, theoretically, between 0.1 and 1000 mm s-1. Experimental constraints may decrease this range. 

Therefore, instead of performing one experiment with a large number of gradient steps, the entire range should be better covered by at least two experiments with a significantly smaller number of gradient steps. The first experiment has a velocity field of view that covers the entire velocity range in a small number of steps. The velocity map is not distorted but small velocities are identified as zero due to the coarse resolution. 

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