MPA smoothing

The two protein bands (2055 and 2077 nm) and the water band (1941 nm) in Figure 6.9a are marked for reference later. Two things should be noted from Table 6.3. First, MPA smoothing degraded the water band from 0.7168 to 0.7115 as the convolution interval increased from 1 (no smoothing) to 25 points. At the same time the peak of the water band shifted from 1941 to 1943 due to a smoothing moment caused by the asymmetry of the water band. Note this point If a band is symmetrical there will be no shift of the peak no matter how large the convolution interval. This one fact makes it impossible to determine a priori the optimum convolution interval. Consequently, unless you know a lot about the characteristics of the noise in your spectrometer plus detailed... 

FIGURE 6.8 Convolution smoothing in the WD versus smoothing via the FD. MPA smoothing involves the convolution of two functions in wavelength space, but only multiplication of two functions in Fourier space. 

FIGURE 6.9 Spectra of wool (a) Original spectrum with a noise spike at 1800 nm, MPA (25 pts) smoothed spectrum, and Fourier (50 pair) smoothed spectrum, (b) MPA smoothing of the noise spike, (c) Polynomial smoothing of the noise spike, (d) Fourier smoothing of the noise spike. 

Figure 6.11a-c gives a comparison of the derivatives from three computational methods (a) MPA a, (b) polynomial b, and (c) Fourier c. The MPA smoothing process used a segment size of 21 points, the polynomial segment size was 25, and the number of coefficient pairs used in the Fourier computation was 69. The Fourier derivatives contain the same number of points as the original spectrum while the convolution techniques drop points on both ends of the spectrum. 

The mats are moved along the line to the press loader. When the loader is filled and the press opens to remove the load of freshly pressed boards, the loader pushes the new boards into the unloader and deposits the load of mats on the press platens. The press closes as quickly as possible to the desired panel thickness. More pressure, as much as 4.8—6.9 MPa (700—1000 psi) is required to press high density dry-process hardboard, because the dry fiber exhibits much more resistance to compression and densification than wet fiber. Press temperatures are also higher, in the range of 220—246°C. No screens are used in the dry-process, but the moisture in the mats requires a breathe cycle during pressing to avoid blowing the boards apart at the end of the cycle. Because no screens are used, the products are called smooth-two-sides (S-2-S), in contrast to the wet-process boards, which have a screen pattern embossed into the back side and are known as smooth-one-side (S-l-S). 

The melt flows from the extmder iato the die where it flows around the bend and around the core tube. On the far side of the core tube, it forms a weld. Melt sticks to and is pulled by the moving wire. Details of the sizes and shapes of the die parts ia contact with the melt are important ia obtaining a smooth coating at high rates. The die exit usually is the same diameter as that of the coated wire and there is Httle drawdown. Die openings are small and pressures iaside the die are high at ca 35 MPa (5000 psi). Wire takeup systems operate as high as 2000 m /min. 

HPC is available in a number of viscosity grades, ranging from about 3000 mPa-s(=cP) at 1% total soHds in water to 150 mPa-s(=cP) at 10% total sohds. HPC solutions are pseudoplastic and exceptionally smooth, exhibiting Htde or no stmcture or thixotropy. The viscosity of water solutions is not affected by changes in pH over the range of 2 to 11. Viscosities decrease as temperature is increased. HPC precipitates from water at temperatures between 40 and 45°C. Dissolved salts and other compounds can profoundly influence the precipitation temperature (50,81). 

It can be shown that if the pressure index of the propellant exceeds 1 the rate of gas increase by factor 2 exceeds the rate of gas loss by factor 1, so that the pressure builds up in the motor, which finally explodes. Quite apart from such an extreme case, a low pressure index in the propellant is desirable so that irregularities in burning are quickly smoothed out with the least effect on rocket performance. It is for this reason that platonising agents mentioned on p. 181 are important, because they enable a very low pressure index to be achieved at ordinary operating pressures of the order of 14 MPa. 

The pressure of argon gas during atomization ranges from 0.03 to 0.1 MPa. The crucible diameter is 75 mm and its rotating speed is up to 400 radians/s. This combination of conditions gives a production rate up to 1 kg/min, l89l The CSC-atomized particles are either spherical or flaky. Spherical particles usually have smooth... 

Fig. 7.8 shows the temperature profiles [temperature (K) versus burning time (s)] in the combustion waves of this propellant at 0.0355 MPa and at 0.0862 MPa. The temperature is seen to increase relatively smoothly in the condensed phase, but then increases with large fluctuations in the gas phase at both pressures. However, the rate of temperature increase is clearly much higher at 0.0862 MPa than at 0.0355 MPa. 

Rocket propellants are very similar to gun propellants in that they are designed to burn uniformly and smoothly without detonation. Gun propellants, however, burn more rapidly due to the higher operating pressures in the gun barrel. Rocket propellants are required to burn at a chamber pressure of 7 MPa, compared with 400 MPa for gun propellant. Rocket propellants must also burn for a longer time to provide a sustained impulse. 

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