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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Kinetics Of A Particle: Force & Acceleration
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Kinetics:
It is the branch of dynamics that deals with the relationship between the change in motion of a body the cause which changes it.
The base of kinetics is Newton's Second law of motion (F = ma).
Theory of Relativity → placed limitations on 2nd law of motion for describing particle motion.
Equations of motion fails to predict exact behavior of particle when it reaches speed of light 0.3 Gm/s.
There are two types of diagram which are described as follows:
Kinetic Diagram → shows inertial forces or net forces of body.
Free Body Diagram (FBD) → show all external forces on body.
If inertia force vector is treated in the same way as force vector → Equilibrium state is called Dynamic Equilibrium.
There are two types of frame of references but we are discussing only one which is:
Newtonian or Inertial Frame of Reference → state of rest or uniform velocity. Newton's laws only valid for non-rotating and non-accelerating reference system which is translating with constant velocity.
General Procedure For Problem Solving:
Select a convenient inertial coordinate system which can be rectangular, normal and tangential or cylindrical coordinates.
Draw FBD showing all external forces.
Draw the kinetic diagram showing inertia force, ma.
Apply equations of motion in scalar form.
Identify the unknowns and solve equation.
Kinematic relation may be applied
Equation Of Motion For a System Of Particles:
Equation of particle is valid for isolated system. Important points are:
Only for inertial frame of references.
Unbalanced force cause acceleration.
Inertial frame of reference does not rotate.
Applying equation of motion:
Mass → resistance to change in velocity (absolute quantity).
When all the forces acting on the particle can be resolved into cylindrical components easily.
Applying equation of motion, we get:
Frictional force always act along tangent in opposite direction.
The angle between tangent and radial line is given by:
Force on a system of particle is totally described as:
References:
Material from Class Lectures + Book named Engineering Mechanics Statics & Dynamics by R.C. Hibbeler (12th Edition) + from YouTube channel named Yiheng Wang for Engineering Dynamics Mechanics + my knowledge.
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Diffusion It is defined as, " The transportation of one atom from one state into other state " . Used for hardening of surfaces like die parts, gear, bolt, machine element. Hardening can be done using Temperature-Heat treatment ( diffusion couple ). There are two types of diffusion: Inter-diffusion ↔ in which atoms tend to migrate from region of high concentration to low concentration . Self-diffusion ↔ in which atoms migrate within a solid. Diffusion Mechanism There can be two conditions of moving atoms Empty spaces between adjacent sites. Atoms have sufficient energy to break bond with neighbors atoms which cause lattice distortion during displacement. If we rise temperature, small fractions of atoms is capable of diffusive motion (which cause lattice distortion). Types of Diffusion 1. Vacancy Diffusion It is defined as, " interchange of an atom from a normal lattice position to the adjacent vacant lattice site " . Extent of vacancy diffusion is a function...
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