Definitions[ edit ] This higher-level cognition was given the label metacognition by American developmental psychologist John H.
There is no math, just good, clear explanations of how it works. It follows the same approach Discuss some word formation processes i the pump tutorial and if you are just starting in this field I recommend you read it first.
NPSHA is a measure that corresponds to the level of pressure at the pump suction.
Normally we measure pressure with a gauge that is calibrated in psig pound per square inch gauge or kPa in the metric system.
This pressure scale is set at zero when there is no pressure or the pressure is equal to atmospheric pressure. The atmospheric pressure at sea level as measured on an absolute scale such as psia pounds per square inch absolute is In the absolute scale, pressure starts at zero which is the lowest possible pressure and means that there is no molecules of matter in the environment that can create pressure such as in outer space.
It then can have any value corresponding to a high pressure environment. The term head in NPSHA has been well explained in the pump tutorialthe head component that we are most interested in here is the static head or the level of fluid above the pump suction. Head is measured in feet in North America and in meters just about everywhere else.
The value of NPSHA will vary between the lowest value of 0 feet, up to the value of the local atmospheric pressure head 34 feet plus the suction static head minus a small quantity which we will get to shortly.
This is possible if there is allot of friction or plugging which increases friction in the suction line. Sometimes these two occur together, when the level is low in the suction tank due to physical constraints or poor level control or other reasons, this decreases the overall NPSHA and a further decrease occurs due to friction.
The manufacturer tests the pump under various suction head conditions and provides a requirement or NPSHR for each flow condition on the characteristic curve of the pump. Why do you have to worry about atmospheric pressure, after all atmospheric pressure is everywhere, how could the operation of the pump be influenced by its value?
Because atmospheric pressure depends on the elevation, the pressure varies significantly depending on the elevation above sea level. Atmospheric pressure gets added to the pressure provided by the static head and if you are at a high elevation atmospheric pressure will be less and therefore the suction pressure will be less.
When you pressurize the tank you start pressurizing from some level, that level is the local atmospheric pressure. If your local atmospheric pressure is 10 psia and you add psia of nitrogen pressure than your total on top of the liquid is psia.
Figure 1 To measure suction pressure two units are typically used, the psia or pounds per square inch absolute or the inch of mercury. Pressure gauges can be purchased that have scales with either one of these two units in North America.
The following figure shows how these two scales can be used. Figure 2 Most pumps can operate with a suction pressure that is below atmospheric pressure.
A pressure that is below atmospheric pressure is referred to as a vacuum. This is also how it is possible for a normal centrifugal pump to lift fluid from an elevation that is below the suction. For more information on low pressure at the pump suction see the pump tutorial.
Figure 3 A pump that operates in this fashion will require a foot valve to keep the liquid in the suction pipe to avoid having to re-prime the pump when it is stopped.
The main measurement we need is the pressure close to the pump suction. But first a digression on what the pressure measurement we take will mean. What happens to the flow and pressure within the pump past the point of measurement.
The next figure shows that the pressure drops considerably as the fluid enters the eye of the pump. This happens for two main reasons: The pressure can be low enough that the liquid will start to boil at this low pressure.
What do you mean the liquid will boil at low pressure? Figure 4 There are two ways to boil a liquid. One way is to increase the temperature while keeping the pressure constant until the temperature is high enough to produce vapor bubbles.7. Dimension 3 DISCIPLINARY CORE IDEAS—EARTH AND SPACE SCIENCES.
E arth and space sciences (ESS) investigate processes that operate on Earth and also address its place in the solar system and the galaxy. Thus ESS involve phenomena that range in scale from the unimaginably large to the invisibly small. Metacognologists are aware of their own strengths and weaknesses, the nature of the task at hand, and available "tools" or skills.
A broader repertoire of "tools" also assists in goal attainment. Discuss some word formation processes in English You should identify at least four and illustrate your discussion with examples of each, refer to relevant sources. Word formation is the process by which a new word is formed.
Study Questions for Books Previously Taught in Young Adult Literature and in Children's Literature. These books can be used for elementary, middle school, and secondary school-aged pupils and now Miguel A Hero Ain't Nothin' But a Sandwich Alice in Wonderland. Belle Prater's Boy Book of Three, The Briar Rose Bridge to Teribithia.
Catcher in the Rye Charlotte's Web Chasing Redbird Child of. The articles in this series define and exemplify the most common word formation processes, or the creation of new words, in English including derivation, back-formation, conversion, compounding, clipping, blending, abbreviations, acronyms, eponyms, coinages, nonce words, borrowing, and calquing.
The above mentioned word formation processes are the most frequent or important in the English language, but it is rarely the case that only one process occurs in one word. Words can be loaned and then back formed, later on gaining an affix.