The Characteristic Curve

FIGURE 6-2. Effect of developing time on photographic emulsion gamma. 

FIGURE 6-4. Characteristic curves of two different emulsions showing different relative speeds. 

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Where Pg is the pressure of vapor in equilibrium with the adsorbed film. The characteristic curve is now just PF In Pq/P versus x (or against [Pg.627]

For a given set of assumptions it is possible to calculate the characteristic curves for the product from the ciystaUizer when it is operated at various levels of fines removal as characterized by Lj. This has been done for an ammonium sulfate crystalhzer in Fig. 18-63. Also shown in that figure is the actual size distribution obtained. In calculating theoretic size distributions in accordance with the Eq. (18-41), it is... 

Variable-Pressure, Variable-Rate Filtration The pattern of this categoiy comphcates the use of the basic rate equation. The method of Tiller and Crump (loc. cit.) can be used to integrate the equation when the characteristic curve of the feed pump is available. 

Another important factor in design is the steepness of the characteristic curve, that is, the variation of pressure ratio with mass flow (see Figure 1-3 ), From consideration of the velocity diagram for 50% reaction, such as (d) of Figure 6-5, it can be shown that the symmetrical arrangement cives... 

The fan volume flow q, and its corresponding Ap,g, can be found when a Ap,o( - chart is drawn the duct parabola and experimental Ap, t both equal f(q ) (Eig. 9.47). The experimental curve Apj j = f q ) is called the fan characteristic curve, and the duct static pressure drop dependency on the duct volume flow is the characteristic curve. The characteristic curve intersection point is called fan operating point. 

Solution. Draw into the iv diagram the characteristic curve of the fan and the duct-pressure-drop volume flow dependency. The latter is a parabola passing through the origin with the following equation ... 

In a Ap-q, chart, the characteristic curve of the ducts is drawn. In the same chart is drawn the characteristic curve of both fans. At each volume flow q, the total pressure of each fan is added. In this w ay, we get a new - q ... 

Consider the fan characteristic curves for two different rotational velocities ft] and n-,. Select the operating point for the characteristic curve as The corresponding point is q,i) for characteristic curve n. ... 

From Eq. (9.136), the characteristic curve of 2 t S drawn when the characteristic curve of is known. 

The speed of an electric motor can be changed by altering the frequency of the electric current. This is because the ratio is the same as 60 or 50 f/p (f = the frequency of the current, p = the number of poles in the stator). Frequency converters are built of electronic components, frequently combined with microprocessors. They provide good motor protection and are superior to the traditional bimetal protection. The characteristic curve for a pump and fan motor is also quadratic, making lower demands to the frequency converters When the frequency of the electrical current is changed in the frequency converter, the main AC supply is transformed into DC. The DC is then treated... 

The measurement range of a vane anemometer is typically between 0.3 and 30 m s E It may start rotating with slightly lower velocities, but due to the characteristic curve having a small nonlinear part in the low-speed end, the useful range is narrower. The actual precision depends on the quality of the instrument however, the inaccuracy may vary between 1% and 5% of the scale. The larger the vane, the higher the accuracy. 

The characteristic curves of each pump must be continuously rising (right to left) as show u for the single pump of Figure 3-35, otherwise with drooping or looped curves they may be tw o flow conditions for any one head. 

Pumps are normally selected to operate in the region of high efficiency, and particular attention should be given to avoiding the extreme right side of the characteristic curve where capacity and head may change abrupdy. 

It is important to recognize that a cenlrijugal pump will operate only along its performance curve [10, II]. External conditions will adjust themselves, or must be adjusted in order to obtain stable operation. Each pump operates within a system, and the conditions can be anticipated if each component part is properly examined. The system consists of the friction losses of the suction and the discharge piping plus the total static head from suction to final discharge point. Figure 3-51 represents a typical system head curve superimposed on the characteristic curve for a 10 by 8-inch pump with a 12-inch diameter impeller. 

Thus, T is a function of any specific impeller. The variation of T with flow defines the characteristic curve of the impeller. 

Figure 4-316 shows the characteristic curves for a new 8-in. OD, 7 8 lobe, and three stages. 

The working pressure limits of the propeller fan, depending on its diameter, are of the order of 150 Pa. The characteristic curve has a pronounced trough , which should be avoided in application if at all possible, since wide variations in air flow can occur for a small change in pressure. Performance varies with aperture shape, clearance and position. 

In reality, the valve characteristic curve is likely nonlinear and we need to look up the technical specification in the manufacturer s catalog. After that, the valve gain can be calculated from the slope of the characteristic curve at the operating point. See Homework Problem 1.33 and the Web... 

Thus, from adsorption data for one gas, data for other gases on the same adsorbent may be found. Several other methods of plotting the characteristic curve have been proposed1(3). 

The characteristic curve of the odor threshold is used. The relative cumulative frequency of positive answers is calculated for each odorant concentration and graphically plotted, while for odor concentration a logarithmic scale is used. The odor threshold can be obtained from the resulting curve as the 50-percentile and so can the associated 16- and 84-percentiles. 

With the development of modern computation techniques, more and more numerical simulations occur in the literature to predict the velocity profiles, pressure distribution, and the temperature distribution inside the extruder. Rotem and Shinnar [31] obtained numerical solutions for one-dimensional isothermal power law fluid flows. Griffith [25], Zamodits and Pearson [32], and Fenner [26] derived numerical solutions for two-dimensional fully developed, nonisothermal, and non-Newtonian flow in an infinitely wide rectangular screw channel. Karwe and Jaluria [33] completed a numerical solution for non-Newtonian fluids in a curved channel. The characteristic curves of the screw and residence time distributions were obtained. 

EXERCISE 1-10 Use the Secondary Sweep to find the characteristic curves of a 2N5951 jFET. SOLUTIOR Draw the circuit below ... 

Run PSpice and plot the results with Probe. The x-axis will automatically be VDS. To plot the characteristic curves, plot the drain current ID(J1) ... 

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