Radiation Heat Transfer

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View Factor Orientation (or View factor or shape factor) plays an important role in radiation heat transfer. View factor is defined as, "fraction of radiation leaving surface 'i' and strike 'j' ". Summation Rule (View Factor) If there is are similar surfaces 'i' and 'j' , then: Blackbody Radiation Exchange Radiation Exchange between Opaque, Diffuse, Gray surfaces in an Enclosure 1. Opaque 2. Surfaces 3. Two surface enclosure Radiation Shield It is used to protect surfaces from radiation act like a reflective surface. References: Material from Class Lectures + Book named Fundamentals of Heat and Mass Transfer by Theodore L. Bergman + My knowledge.  Photoshoped pics  are developed.  Some pics and GIF from Google.   Videos from YouTube ( Engineering Sights ).
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Leveling

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LEVELING

Definition :

The procedure for determining differences in elevation between points that are some distance away from each other is called Levelling.

Types Of Leveling :

There are many types but we discussed some of them here. 

1. Differential Leveling :

It is used to determine the differences in elevation between points that are some distance away from each other by level together with a graduated measuring rod.


2. Reciprocal Leveling :

Reciprocal leveling is employed to determine the difference in elevation between two points when it is difficult to keep back sight(B.S.) and fore sight(F.S.) short and equal.

3. Profile Leveling :

It is a method of surveying that has carried out along the central line of a track of land.

4. Cross-section Leveling :

A profile leveling in which we determine the elevation of series of points or lines at right angle to lengthwise along a highway. 
  • Bench Mark Leveling ➤ using Bench mark for leveling 
  • Three-wire Leveling  ➤ using stadia cross hair
  • Trigonometric Leveling  ➤ using trigonometry 

Terms Related to Leveling :

  • Elevation : A vertical distance above the reference datum to the center of instrument. 
  • Bench Mark : A point of known elevation.
  • Temporary Bench Mark (TBM) : A semi-permanent point of known elevation.
  • Turning or Change Point : A point temporarily used to transfer an elevation.
  • Height of Instrument (HI) : Vertical distance between line of sight & mean sea level (MSL).

Methods Of Leveling :

1. HI or Line of Collimation Method.
2. Rise & Fall Method.

1. Leveling By HI Method :

The elevation of unknown points can be calculated by subtracting the staff reading from height of instrument to get reduction of level.
          HI = BS + RL 
     RL = HI -  BS (Staff Reading)      
 

2. Leveling By Rise & Fall Method :

Rise and fall method of leveling is used to determine the difference in elevations between points and also we can calculate the reduce level of points. 

Tigonometric Leveling

Trigonometric leveling is an efficient method for the determination of reduce level of points.

Note : Anyone who is interested to get more problems related to leveling, he or she will contact me by comment below and I will send you problems of leveling. 







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