Engineering Drawing SImple Notes

Engineering Drawing Notes

Projection is defined as the view of an object into a plane called “projection Plane.”

Two Classification of Projection

1.       Parallel Line – plane drawing of an object.

2.       Perspective – multiple view drawing.

Parallel Line Drawing

1.       Orthographic Drawing – drawing of two dimensional object (2D).

2.       Oblique Drawing

3.       Isometric Drawing – drawing with angles on both sides.

4.       Section Drawing – allows to picture out the inside feature of an object.

Equipment Used in Drawing

1.       Pencil – HB and 2H

2.       Eraser

3.       Ruler

4.       Triangular Scale

5.       T Square

6.       French Curve

7.       Erasing Shield

8.       Protractor

9.       Engineering Pen

10.   45 Degrees and 90/60 Degrees Triangles

11.   A3

Lines used in Drawing

Thin Lines	Uses	Dimension (Length)
Hidden Lines	Project inside lines
Phantom Lines	Show movement
Long break line	Short cut of drawing a long line
Dimension / Extension Line	For providing extension lines
Section Lines	To show inside features of a drawing
Center Line	To indicate the center of an object especially circular drawings
Stitch line	Used for stitches representation
Thick Lines	Uses	Dimension (Length)
Visible Lines	To show visibility of a line
Chain line	Representation of a chains
Short break lines	Narrowing the drawing of a line
Cutting / Viewing Plane	For viewing

Perspective Drawing Terms

1.       Station Point – it is the location of the observer of an object to be projected.

2.       Horizontal Plane – it is the plane at an eye level.

3.       Picture Plane – it is the plane perpendicular to horizontal plane.

4.       Horizontal Ground Plane – it is the plane at the lower portion of the horizontal plane.

5.       Horizon Line –the line of intersection of the picture plane and the horizontal plane.

6.       Ground Line – the line of intersection f the picture plane and the ground plane.

7.       Axis of View – it is a line view of a horizontal plane. This is also known as the line of sight.

8.       Center of vision – piercing point of the Axis of vision and the Picture Plane.

3 Principal Views

1.       Top View – horizontal plane

2.       Front View – Vertical

3.       Side View – profile plane

6 Principal Views – expansion of 3 principal views

1.       Top View

2.       Back view

3.       Front View

4.       Left Side View

5.       Right Side View

6.       Bottom View

The Auxiliary View – the view on which is not included in 6 principal views. It is a Slanting Plane.

Uses of Auxiliary View

1.       Find for a true length

2.       Find for a Point View

3.       Find for an Edge View

4.       Find for a True Size

5.       Find for a true angle

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The Importance of Statistic and Probability in Electrical and Computer Engineering

A Research on the Role of
Statistic and Probability in ELECTRICAL and COMPUTER ENGINEERING


                        Electrical and Computer engineers have played a central role in the design of modern information and communications systems. Practical current applications from various areas of electrical and computer engineering are used to show how averages and relative frequencies provide the proper tools for handling the design of systems that involve randomness. These application areas include wireless and digital communications, digital media and signal processing, system reliability, computer networks, and Web systems. This research aims to point out the important role of Statistic and Probability in the field of Electrical Engineering.


General Role of Statistic and Probability

1.      Mathematical models relate important system parameters and variables using mathematical relations. They allow system designers to predict system performance by using equations when experimentation is not feasible or too costly.

2.      Computer simulation models are an alternative means of predicting system performance. They can be used to validate mathematical models.

3.      In deterministic models the conditions under which an experiment is performed determine the exact outcome. The equations in deterministic models predict an exact outcome.

4.      In probability models the conditions under which a random experiment is performed determine the probabilities of the possible outcomes. The solution of the equations in probability models yields the probabilities of outcomes and events as well as various types of averages.

5.      The probabilities and averages for a random experiment can be found experimentally by computing relative frequencies and sample averages in a large number of repetitions of a random experiment.

6.      The performance measures in many systems of practical interest involve relative frequencies and long-term averages. Probability models are used in the design of these systems.


Some of the Specific Application of Statistic and Probability

1.      Computer memories                                                                                                                
    Suppose you are designing a computer memory to hold k-bit words. To increase system reliability, you employ an error-correcting-code system. With this system, instead of storing just the k data bits, you store an additional l bits (which are functions of the data bits). When reading back the (k+l)-bit word, if at least m bits are read out correctly, then all k data bits can be recovered (the value of m depends on the code). To characterize the quality of the computer memory, we compute the probability that at least m bits are correctly read back. You will be able to do this after you study the binomial random variable.


2.      Optical communication systems                                                                              
     Optical communication systems use photodetectors to interface between optical and electronic subsystems. When these systems are at the limits of their operating capabilities, the number of photoelectrons produced by the photodetector is well-modeled by the Poisson random. In deciding whether a transmitted bit is a zero or a one, the receiver counts the number of photoelectrons and compares it to a threshold. System performance is determined by computing the probability that the threshold is exceeded.


3.      Wireless communication systems                                                                    
    In order to enhance weak signals and maximize the range of communication systems, it is necessary to use amplifiers. Unfortunately, amplifiers always generate thermal noise, which is added to the desired signal. As a consequence of the underlying physics, the noise is Gaussian. Hence, the Gaussian density function which plays a prominent role in the analysis and design of communication systems.

4.      Variability in electronic circuits.                                                      
   Although circuit manufacturing processes attempt to ensure that all items have nominal parameter values, there is always some variation among items. How can we estimate the average values in a batch of items without testing all of them? How good is our estimate? You will learn how to do this when you study parameter estimation and confidence intervals. Incidentally, the same concepts apply to the prediction of presidential elections by surveying only a few voters.


5.      Computer network  traffic.                                                                                                         
    Prior to the 1990s, network analysis and design was carried out using long-established Markovian models. You will study Markov chains. As self-similarity was observed in the traffic of local-area networks, wide-area networks, and in World Wide Web traffic, a great research effort began to examine the impact of self-similarity on network analysis and design. This research has yielded some surprising insights into questions about buffer size vs. bandwidth, multiple time- scale congestion control, connection duration prediction, and other issues.

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Simple Guide to Subject Verb Agreement

Subject – Verb Agreement

Rule

1. The number of subject should agree with the number of verbs.

2. Measurements (fraction, percentages, amounts, distances) uses SINGULAR VERB.

3. When encountering an “OF PHRASE” consider the singularity/plurality of the nearest noun to the verb.

4. Indefinite Quantifiers (few, much, all, many…) consider the singularity/plurality of the nearest noun to the verb.

5. “Either/or,” consider the second noun for the basis of singularity/plurality of the verb.

6. Noun connected by “and” is plural and must use plural verb except when referring to one thing.

7. “or” and “nor,” consider the singularity/plurality of the nearest noun to the verb.

8. When encountering a prepositional phrase, always ignore it because it does not contain the subject.

9. Indefinite pronoun (everybody, anybody…) uses singular verb.

10. The expression, “the number” takes a singular verb.

11. The expression, “a number” takes a plural verb.

12. The positive idea, not the negative idea in the sentence agrees in number with a verb.

 Notes:

o   Most Nouns that ends with “s” is plural.

o   Verb that ends “s” is singular.

Arrangement of Adjective

•         Article/possessive adjective/demonstrative adjective/other determiners

                        Examples: both/this/my/an/several

•         Numerals/ordinals

                        Examples: first/last/fifth

•         Quantifiers

                        Examples: few/a little/plenty

            •      Qualitative adjectives

                        Examples: ugly/main/famous

•         Size

                        Examples: big/heavy

            •      Age/temperature

                        Examples: hot/old

•         Shape

                        Examples: round/circular

            •       Color

                        Examples: red/dark blue

            •       Origin

                        Examples: Elizabethan/rural

            •        Material/noun

                        Examples: plastic/table

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Material Science : Chapter 2 Notes

Chapter 2

Properties of solid metals depend on geometrical atomic arrangements and also the interactions that exist among constituent atoms or molecule.

Charge	Weight	Charge Equivalent
Electron	9.11 x  kg	1.602 x  C
Proton	1.67 x  kg	-1.602 x  C
Neutron	1.67 x  kg	0

Isotope – elements that have two or more different atomic masses.

A = Z + N

Atomic Mass = (# of protons) + (# of neutrons)

                A – atomic mass. The sum of the masses of protons and electrons within the nucleus

                Z – atomic number. Number of Protons in nucleus. Ranges from 1 (Hydrogen) to 92 (Uranium). For neutral atom, #                 of proton = # of electrons

                N – neutrons;

1amu/atom = 1 molecule = 1g/mol

Isotopes – elements that has uniform # of protons but differs in # of neutrons.

Atomic Weight – corresponding average weight of the natural occurring isotopes.

Quantum Mechanics is set of principle and law that govern system of atomic and subatomic entities.

“Electrons are permitted to have only specific values of energy”

Quantum Numbers – size, shape, spatial orientation.

Quantum Number	Shell Designation	Subshells	Number of States	Number of Electrons
				Per subshell	Per Shell
1	K	S	1	2	2
2	L	S	1	2	8
		p	6	6
3	M	S	1	2	18
		P	3	6
		D	5	10
4	N	S	1	2	32
		P	3	6
		D	5	10
		F	7	14

Electron States- values of energy that are permitted for electrons.

Pauli Exclusion Principle states that each electron state can hold no more than two electrons, which must have opposite spins. S – 2, P – 6, D – 10, F – 14

                Ground state – when all lowest possible energies is occupied.

                Electron Configuration represents the manner in which these states are occupied.

                Valence Electrons are those occupy the outermost shell.

Periodic Table

Elements are classified according to electron configuration and increasing atomic #, in seven horizontal rows called periods

1A

O

2A

3A

4A

5A

6A

7A

3B

4B

5B

6B

7B

8

8

8

IB

2B

O – inert gas, filled electron shell, stable.

7A (halogens), 6A – one or two electron deficient

1A (Alkali), 2A (Alkaline) – one or two excess electron

3B-2B –transition metal, partially filled d electron state

3A-5A – has character between metal and nonmetal.

Electronegative – right hand side of the PT. (donate electron to become positively charged ion)

Electropositive- left hand side of the PT. (Accept electron to become negatively charged  ion)

Bonding Energies

                Fn = Fa + Fr                                         0 = Fa + Fr                                           En = Ea + Er

Primary Interatomic Bonds

1.       Ionic Bonding (donates electrons to nonmetallic) – occurs between metallic and nonmetallic elements.

                % ionic character = ( 1 – exp [-0.25 (Xa – Xb)^2 ]) x 100; Xa, Xb – electronegativity of the elements

2.       Covalent Bonding (sharing electrons) – occurs on nonmetals

                               

3.       Metallic Bond – occurs on metals and alloys

                Ea = -A / r

                Eb = B / r^n ; n=8

                A= k (z1 e)(z2 e);              e=1.602 x10^-19 c,           k=9x10^

Secondary Bonding / Van der Waals Bonding – occurs only when three bonding are present.

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