Size and Speed

In a relational database, data in a column may be indexed. This is explained in a later section of this chapter. If the relational table contains an index, many operations on the table can be greatly accelerated. Indexing is not possible in most spreadsheet programs. 

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As illustrated in Figure 12, a number of different feeding and discharge arrangements as well as surface sizes and speeds lend versatihty to these... 

The kieis aie of varying sizes and production units can handle from 225—1400 kg, adjusting proportionally the pump size and speed. Most machines are highly versatile so as to accommodate the kind of textile being dyed they are able to control rate of temperature rise, volume ofHquor flow, and time of dye apphcation. 

Office equipnient is an end use that generally is regarded to consist of five major products personal computers, monitors, copiers, printers, and fax machines. This equipment can be defined by characteristics such as size and speed. Although office equipnient is used in homes, this article focuses on office equipment energy use in actual offices. 

B. Frame size. (Usually applicable only when ordering replacement motors or for special applications. Size usually must be at least as large as manufacturer s standard for motor size and speed.)... 

The other drawback is simply one of economics. Because pumps come in a variety of shaft sizes and speeds, the use of this type of seal requires inventorying several sizes of spare springs, which ties up capital. 

In a contribution to the first conference on physics and computation held at MIT in 1982 [land82b], Minsky considered whether a universe satisfying the following two conditions could exist [minsky82] (1) each volume of space contains a finite amount of information, and (2) over a suitable range of size and speed, the mechanics of the universe are approximately classical. 

Envisioning space-time as a four-dimensional CA lattice, wherein sites take on one of a finite number of values and interact via a local dynamics, Minsky explored various elementary properties of this universe particle (or packet ) size and speed, time contraction, symmetry, and how the notion of field might be made palatable within such a framework. 

Effects of agitator size and speed on bead size (microns). 

Figure 4. Effects of prepolymerizer agitator size and speed on the mean particle...

The efficiency of a pump depends upon the pump and impeller design, the size and speed of the impeller, and the conditions under which it is operating and is determined by tests carried out by the pump manufacturer. This will be discussed in more detail later. 

This shows that the pump head is determined primarily by the size and speed of the impeller and the pump efficiency, independent of the flow rate of the fluid. This is approximately correct for most centrifugal pumps over a wide range of flow rates. However, there is a limitation to the flow that a given pump can handle, and as the flow rate approaches this limit the developed head will start to drop off. The maximum efficiency for most pumps occurs near the flow rate where the head starts to drop significantly. 

To prevent cavitation, it is necessary that the pressure at the pump suction be sufficiently high that the minimum pressure anywhere in the pump will be above the vapor pressure. This required minimum suction pressure (in excess of the vapor pressure) depends upon the pump design, impeller size and speed, and flow rate and is called the minimum required net positive suction head (NPSH). Values of the minimum required NPSH for the pump in Fig. 8-2 are shown as dashed lines. The NPSH is almost independent of impeller diameter at low flow rates and increases with flow rate as well as with impeller diameter at higher flow rates. A distinction is sometimes made between the minimum NPSH required to prevent cavitation (sometimes termed the NPSHR) and the actual head (e.g., pressure) available at the pump suction (NPSHA). A pump will not cavitate if NPSHA > (NPSHR + vapor pressure head). 

In a centrifuge, the position of the overflow weir is similarly determined by the relative amounts of the heavier and lighter liquids and their densities, along with the size and speed of the centrifuge. The feed stream may consist of either the lighter liquid (1) dispersed in the heavier liquid (2) or vice versa. An illustration of the overflow weir positions is shown in Fig. 12-6. Because there is no slip at the interface... 

The availability of power and torque to the shank of the screw is extremely important to the success of an extrusion process, especially if modifications to the line are planned to increase the rate. That is, the proper level of power must be available at the proper screw speed. Thus, the motor size and speed, belt sheaving if used, and gearbox reduction must be specified to provide enough power to the screw to plasticate and pump the resin at a high rate. 

Due to the results mentioned in Section 2.4.1 by Tobias et al. [110] and Gosh [6] et ah, the authors tested the response (not using the MGO equipment) of the MISiG-FET sensors at 500°G for different constant current levels. A current of 65 juA showed the same fast speed of response as for normal operation at 100 juA. For a constant current of 500 /t A, the MISiG-FET showed the same size and speed of response but also a slow drift of the baseline, which was not sensitive to a change between oxygen and hydrogen. 

Centrifugation. Centrifuges of many sizes and speeds are used in the laboratory to remove debris as well as to collect precipitated proteins and other materials at various steps in a purification scheme. The most remarkable are the ultracentrifiiges which produce forces greater than 4 x 105 times that of gravity. They can be used both for separation of molecules and for determination of Mr (see Section C). 

Impeller Size and Speed at a Specified Power Input... 

For a vessel containing 5000 gal of liquid with specific gravity = 0.9 and viscosity of 100 cP, find size and speed of a pitched turbine impeller to deliver 2 HP/1000 gal. Check also the superficial linear velocity and the blend time. 

Fig. I. Constant power, eftect of impeller size, and speed on flow and turbulence...

Detailed modelling, or numerical simulation, provides a method we can use to study complex reactive flow processes (1). Predictions about the behavior of a physical system are obtained by solving numerically the multi-fluid conservation equations for mass, momentum, and energy. Since the success of detailed modelling is coupled to one s ability to handle an abundance of theoretical and numerical detail, this field has matured in parallel with the increase in size and speed of computers and sophistication of numerical techniques. 

So the animal has to be sufficiently large and fast, because size and speed act in the same way. Therefore, really tiny creatures have problems. D Arcy Thompson (quoted in [134]) has put it in this way ... 

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