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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Frames and Machines
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Truss and it's Types:
Truss is a structure of connected elements forming triangular units, and a bridge whose load-bearing superstructure is composed of a truss.
There are three types of truss and they are:
1. Simple Truss:
A truss is a structure composed of slender members joined together at their end points.
2. Planar Truss:
Planar truss lies in single plane and typically used in parallel to form roofs and bridges.
3. Space Truss:
A space Truss consists of members joined together at their ends to form a stable three-dimensional structure.
Assumptions for Designing Truss:
To design the truss, we have two assumptions:
All loadings are applied at the joints.
The members are joined by smooth pins.
The Method of Joints:
In order to analyze or design a truss, it is necessary to determine the forces in each of its members. Method of joints consists of fool owing steps:
Truss is in equilibrium so does its joints.
Draw Free-body diagrams for each joint.
Apply the force equilibrium equations and obtain the required ones.
ΣFx = 0
ΣFy = 0
The Method of Sections:
By using the method of sections, you need to follow the instructions below:
Truss is in equilibrium so does the segments of truss.
Draw free Body diagram indicating all forces.
Cut the free Body diagram into its simple parts.
Apply the equilibrium equations to find the required forces and moments.
ΣFx = 0
ΣFy = 0
ΣMo = 0
Zero Force Members:
Zero-force members in a truss members which do not have any force in them. Zero-force members are used to increase the stability of the truss during construction and to provide added support of the loading is changed.
Frames:
Frames used to support loads which are often composed of pin-connected multi-force members that are subjected to more than two forces.
Machines:
Machines contain moving parts which are often composed of pin-connected multi-force members that are subjected to more than two forces.
TAPING CORRECTIONS There are two types of corrections depending upon the type of errors in tape due to the different conditions. 1. Systematic Errors : Slope Erroneous tape length Temperature Tension Sag 2. Random Errors : Slope Alignment Marking & Plumbing Temperature Tension & Sag 1. Temperature Correction It is necessary to apply this correction, since the length of a tape is increased as its temperature is raised, and consequently, the measured distance is too small. It is given by the formula, C t = 𝛼 (T m – T o )L Where, C t = the correction for temperature, in m. 𝛼 = the coefficient of thermal expansion. T m = the mean temperature during measurement. T o = the tempe...
Introduction Existence of perfect crystals (without defects) are ideal. Instead, we have kinds of imperfection. Ques: Why study imperfections in Solids? When pure metals alloyed (addition of impurities ) like Sterling Silver ↣ 92.5 % Ag and 7.5 % Cu , Cartridge Brass ↣ 70 % Cu and 30 % Zn . These impurities play an important role in semiconductors properties, steel composition, etc. Atomic defects are responsible for reduction gas pollutants emissions in automobiles. Ques: How polluting gases converted into non-pollutant gases? Ans: Molecules of pollutant gases become attached to surface defects of crystalline material. Hence it convert into less-polluting substance. Types of Defects (Imperfections) in Solids There are four types of defects: Point (or Zero-D) Defects Linear (or 1-D) Defects Planar (or 2-D) Defects Bulk (or 3-D) Defects 1. Point Defects It is defined as, " defects associated with one or two atomic position " . Point defects are further divided into tw...
Reynolds Number: Reynolds Number is the ratio of Inertial forces to the Viscous forces. By knowing this number, one can describe the flow whether the flow is laminar, turbulent or transitional flow. There are three possibilities of the range of Reynolds Number: If Reynolds number < 2100 or 2300 ⟺ Laminar Flow If Reynolds number > 4000 ⟺ Turbulent Flow If 2300 < Reynolds number < 4000 ⟺ Transitional Flow In case of different shapes other than circle, the formula for Reynolds Number remain the same however diameter involves in the formula become Hydraulic Diameter which is given by: For pipe: Critical Reynolds Number ⟾ The Reynolds number at which the flow becomes turbulent Re cr For different shapes, the hydraulic diameters are given by: Completely Filled Flow In Closed Channel: If pipe is is considered to filled completely with closed channel, then following are the conditions which...
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