Performance characteristic curve

Fig. 4.10. Performance characteristic curves of screening tests of binary classifications a ideal curve shape, b experimentally obtained curve... 

Another way to characterize the performance of screening methods for binary classification is the construction of performance curves. A performance characteristic curve (PCC) represents the probability of positive test results vs the concentration of the analyte as shown in Fig. 4.10. 

In this spirit, an approximate dynamic model was developed that is based on pervaporation performance characteristic curves. Sander and Soukup give curves for the ethanol-water system showing how the flux of water through a pervaporation membrane and the composition of the permeate vapor vary with the concentration of ethanol in the liquid feed. Figures 14.1a and b reproduce these curves. Note that these curves show concentrations in wt% and mass flowrates. 

The generalized use of computers makes seemingly complex calculations quite easy to perform however, curves and tables are still invaluable when one needs to obtain approximate values or to take into account the sensitivity of a property to operating conditions or to a mixture s characteristics. 

The ratio of stress to strain in the initial linear portion of the stress—strain curve indicates the abiUty of a material to resist deformation and return to its original form. This modulus of elasticity, or Young s modulus, is related to many of the mechanical performance characteristics of textile products. The modulus of elasticity can be affected by drawing, ie, elongating the fiber environment, ie, wet or dry, temperature or other procedures. Values for commercial acetate and triacetate fibers are generally in the 2.2—4.0 N/tex (25—45 gf/den) range. 

Stress—Strain Curve. Other than the necessity for adequate tensile strength to allow processibiUty and adequate finished fabric strength, the performance characteristics of many textile items are governed by properties of fibers measured at relatively low strains (up to 5% extension) and by the change ia these properties as a function of varyiag environmental conditions (48). Thus, the whole stress—strain behavior of fibers from 2ero to ultimate extension should be studied, and various parameters should be selected to identify characteristics that can be related to performance. 

Engineering factors include (a) contaminant characteristics such as physical and chemical properties - concentration, particulate shape, size distribution, chemical reactivity, corrosivity, abrasiveness, and toxicity (b) gas stream characteristics such as volume flow rate, dust loading, temperature, pressure, humidity, composition, viscosity, density, reactivity, combustibility, corrosivity, and toxicity and (c) design and performance characteristics of the control system such as pressure drop, reliability, dependability, compliance with utility and maintenance requirements, and temperature limitations, as well as size, weight, and fractional efficiency curves for particulates and mass transfer or contaminant destruction capability for gases or vapors. 

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. 

The affinity laws relate the performance of a known pump along its characteristic curve to a new performance curve when the speed is changed. This would represent the same family of pump curves. As an example, see Figures 3-36A, B, and G. 

Range 1 of the mud pump performance characteristic is defined by the performance of the smallest liner, and range 2 is defined by the remaining liners. The pressure loss in a circulating system, except for bit (p ), can be estimated from numerous theoretical formulas or from a flowrate test. Data obtained from a flowrate test can be approximated using a curve-fitting technique by the following function ... 

Selection should be made for minimum power input, which is also likely to be the quietest fan for the duty. Performance is usually quoted for a standard condition of 1.2 m /kg. Calculations of system resistance are best carried out at the same condition. The user may find only the static pressure quoted. If total or velocity pressure are also quoted or the outlet velocity can be calculated the designer can calculate how much pressure can be recovered after the exit. Any mismatch due to difficulty in calculating system resistance will cause the volume to rise or fall, to settle on the fan characteristic curve. 

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. 

Aging studies, performed in the laboratory, are useful for confirming theoretical models describing the behavior of the object at short-, medium-, and long-term intervals. Formed alteration products, (e.g., by oxidation, reduction, polymerization, scission, hydration, dehydration, dehydrogenation, etc.) are the target compounds in such studies. Three-dimensional (3D) diagrams can be built from the spectra or other characteristic curves obtained at different times. 

IUPAC.-Working Party on "The Relationship of Performance Characteristics to Basic Parameters of Polymers . This sample has been investigated in transdecalin at 160° C. Fig. 3.8 shows the extinction angle curves obtained for the three indicated concentrations as functions of A linear extrapolation at various /Sy.urvalues was possible and led... 

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