Utilization factor

Alkali sihcates are used as components, rather than reactants, in many appHcations. In many cases they only contribute partially to overall performance. Utility factors are generally not as easy to identify. Their benefit usually depends on the surface and solution chemical properties of the wide range of highly hydrophilic polymeric siUcate ions deUverable from soluble sihcate products or their proprietary modifications. In most cases, however, one or two of the many possible induences of these complex anions cleady express themselves in final product performance at a level sufficient to justify their use (102). Estimates of the 1995 U.S. consumption of sodium sihcates are shown in Table 6. 

DP Speed Factor. Pumping-speed efficiency depends on trap, valve, and system design. For gases having velocities close to the molecular velocity of the DP top jet, system-area utilization factors of 0.24 are the maximum that can be anticipated eg, less than one quarter of the molecules entering the system can be pumped away where the entrance area is the same as the cross-sectional area above the top jet (see Fig. 4). The system speed factor can be quoted together with the rate of contamination from the pump set. Utilization factors of <0.1 for N2 are common. 

Figure 9-9. Effect of velocity and air angle on utilization factor.

In most designs, the reaetion of the turbine varies from hub to shroud. The impulse turbine is a reaetion turbine with a reaetion of zero (R = 0). The utilization factor for a fixed nozzle angle will increase as the reaction approaches 100%. For = 1, the utilization factor does not reach unity but reaches some maximum finite value. The 100% reaction turbine is not practical because of the high rotor speed necessary for a good utilization factor. For reaction less than zero, the rotor has a diffusing action. Diffusing action in the rotor is undesirable, since it leads to flow losses. 

The 50% reaction turbine has been used widely and has special significance. The velocity diagram for a 50% reaction is symmetrical and, for the maximum utilization factor, the exit velocity (V4) must be axial. Figure 9-11 shows a velocity diagram of a 50% reaction turbine and the effect on the utilization factor. From the diagram IV = V4, the angles of both the stationary and rotating blades are identical. Therefore, for maximum utilization. 

Load utilization factor Ratio of the effective load in a given space to the load supplied. 

Manufacturing efficiency embodies a wide variety of topics far beyond the scope of this book. However, a materials utilization factor will be defined and characterized for composite materials and metals as a... 

In contrast, with composite materials, the materials utilization factor is rarely higher than 1.2 to 1.3. That is, only a maximum of 20-30% of the material is wasted with composite structures. Whereas obviously with a materials utilization factor for some metal parts of 15-25, the waste is 1500-2500% Those are not individually typical numbers, but are the worst cases in both situations, i.e., for metals and composite materiais. For metals, there are many, many operations for which the waste factor is very iow. And for composite materials there are also many situations where the waste factor is much lower than 20-30%. The point is that the worst-case situations are totaliy different for these two kinds of materials based on the way objects are inherently created with the two different types of materials. Composite materials are built up until the limits of the desired geometry are reached. At that point, the layup operation simpiy ceases. Composite materials and structures are fabricated in as ciose to the final configuration as possible, i.e., so-calied near-net shape. 

The mechanical support by the tube allows the use of fairly light active material. This means high porosity and a high utilization factor. 

The problem could have been resolved by running two injections, either with different wavelength settings and/or with different dilutions injected, but this would have appreciably increased the workload of the technicians and the utilization factor of the instrument. Without an additional instrument, the laboratory would have lost much of its flexibility to schedule additional analyses at short notice. Another solution would have been to utilize a programmable detector that switches wavelengths between peaks, but that only works if the weakly detected component strongly absorbs at some other wavelength. 

In reality, the queue size n and waiting time (w) do not behave as a zero-infinity step function at p = 1. Also at lower utilization factors (p < 1) queues are formed. This queuing is caused by the fact that when analysis times and arrival times are distributed around a mean value, incidently a new sample may arrive before the previous analysis is finished. Moreover, the queue length behaves as a time series which fluctuates about a mean value with a certain standard deviation. For instance, the average lengths of the queues formed in a particular laboratory for spectroscopic analysis by IR, H NMR, MS and C NMR are respectively 12, 39, 14 and 17 samples and the sample queues are Gaussian distributed (see Fig. 42.3). This is caused by the fluctuations in both the arrivals of the samples and the analysis times. 

Fig. 42.4. The ratio between the average waiting time (iv) and the average analysis time (AT) as a function of the utilization factor (p) for a system with exponentially distributed interarrival times and analysis times (M/M/1 system).

By automation one can remove the variation of the analysis time or shorten the analysis time. Although the variation of the analysis time causes half of the delay, a reduction of the analysis time is more important. This is also true if, by reducing the analysis time, the utilization factor would remain the same (and thus q) because more samples are submitted. Since p = AT / lAT, any measure to shorten the analysis time will have a quadratic effect on the absolute delay (because vv = AT / (LAT - AT)). As a consequence the benefit of duplicate analyses (detection of gross errors) and frequent recalibration should be balanced against the negative effect on the delay. 

Pmca = (Qd/QTkd) -100% - is the utilization factor (%) Qrhd - theoretical discharge capacity. 

Figure 8. The experimental data and computed curve of the active material utilization factor...

Figure 8 provides a comparison of theoretically computed vs experimental dependences of the active material utilization factor for the investigated electrode. Analytical equations (24) and (25) were used to calculate polarization as a function of the oxidation state, and to calculate the limiting value of the oxidation state as the function of the discharge current (see Figures 7 and 8). 

The expression for the active material utilization factor shows that in the process considered, it is impossible to achieve full utilization of the active reagents in the galvanostatic mode. 

In a study by Fincke and Sherman (JL3), the calcium of spinach was not utilized as well as that from milk however, the calcium of kale, which is low in oxalic acid (3,4), was about as available as that from milk. The calcium utilization factor was determined by dividing the weight of calcium stored by the weight of calcium ingestion. Rats 4 weeks old were fed for 60 days a diet in which most of the calcium was supplied by skim milk, or in which half of the skim milk was replaced by dried spinach or dried kale in amounts to provide the same amount of calcium. The diets contained about 0.3% calcium and 10% butter fat. It was concluded that the poor utilization of the calcium of spinach was due to the oxalic acid in spinach. 

Figure 3. Calcium utilization factor of rats fed control diet (1), turnip greens (2), tendergreens (3), collards (4), kale (5), and New Zealand spinach (6). Adapted from Ref. 18.

Therefore, the combined power and heat cogeneration energy utility factor (EUF) is... 

Determine the rate of heat supply, net power output, process heat output, cycle efficiency, cogeneration ratio, and energy utility factor of the cycle. 

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