engineering carlos a. santos silva september 23 th, 2009
TRANSCRIPT
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EngineeringCarlos A. Santos SilvaSeptember 23th, 2009
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WHAT IS ENGINEERING?
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The roots
•Ingenium [Latin]:
• innate quality, especially mental power, hence a clever invention
= Genious [English]
•Engine:
•Military machine / machine
•Engineer:
•Operator of an engine
•Engineering:
•Military engineering (roads, bridges, vehicles)
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Definition
Accreditation Board for Engineering and Technology:• The creative application of scientific principles to design or develop structures,
machines, apparatus, or manufacturing processes, • or works utilizing them singly or in combination; • or to construct or operate the same with full cognizance of their design; • or to forecast their behavior under specific operating conditions; • all as respects an intended function, economics of operation and safety to life
and property;
“Scientists study the world as it is; engineers create the world that has never been” [T. von Kármán]
“Apply scientific knowledge and technology to solve real problems”
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HISTORY
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The Greeks
Archimedes Screw (Holand)
“Give me a leverand I will lift the world”
Heat-Ray Syracuse
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The Romans
Criptoportic(Lisbon,Portugal)
Aqueducts(PontduGard,France)
ViaApia (Italy)
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The Egyptians, The Chinese, The Arabs
Great Wall(Chinese 500BC-1700)
5 machines(Al-Jazari 1200)
Papyrus scroll(Imhotep)
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16th to 19th Century
Electrical Motor(Hungary 1821)
One span bridge(Leonardo Da Vinci)
Steam Governour(James Watt 1788)
Siemens Telegraph(Germany1856)
Jaquard loom(France 1801)
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20th Century
Transistor(US 1947)
Ford T(US 1908)
Jet Plane(Germany 1929)
ENIAC(US1946)
Space shuttle(US1981)
Panama Canal(US1914)
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TYPES OF ENGINEERING
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Traditional branches
•Civil Engineering•Mining Engineering•Mechanical Engineering•Chemical Engineering•Electrical Engineering•Aeronautics Engineering•Physics Engineering
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New branches
•Computer and Software Engineering•Bio – Engineering•Molecular Engineering•Nanotechnology Engineering•Mechatronics Engineering•Aerospace Engineering
•Engineering Systems
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Engineering Systems
“study dealing with diverse, complex, physical design problems that may include components from several engineering disciplines, as well as economics, public policy, and other sciences”•Examples of complex systems:• Internet• Supply Chains• Air-traffic control• Energy networks
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ENGINEERING MINDSET
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Solve problems by finding solutions
"Everything should be made as simple as possible, but not simpler.“ [A. Einstein]
Create model that represents the problem
Understand problems and test solutions
Design multiple solutions
Evaluate options
Choose solution
Trade off between requirements fulfillment, complexity of manufacturing, safety….
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Characteristics
•Build models• Abstraction•Design solutions• Science knowledge • Deduction• Analogy•Make choices• Experience • Intuition
Simple problems:
Show what to do: theory, application, heuristics, examples to train theory
Compound problems:
Case-studies: get information and apply accordingly
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Engineers….
•Know that there is more than one solution
•The best solution might not be the perfect solution
•The result might not be exactly as previewed, but it is within an interval
•Have to know science (physics)
•Deduct results (general premises to particular conclusions)
•Establish analogies (transferring information from a particular case to other)
•Class1- Defining Engineers
• Battle against uncertainty
• Result driven
•
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Why Physics?
•Understanding of Nature• Discovering the laws governing the universe and predict how it will behave
Matter:
Anything that has weight
Light:
Anything that can travel trough empty space and has no weight
Tools• Scientific method: theory to explain and predict, experiments to demonstrate• Reductionism: isolate system to study•Measurement System• Scaling• Estimates• Vectors• Conservation Law• Simplifying assumptions
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INTRODUCTION TO ENGINEERING
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Program and Evaluation
1. Engineering and tools for Engineering
2. Kinematics and Dynamics
3. Waves, Atom and Optics
4. Electricity and Magnetism
5. Electrical Systems
6. Thermodynamics
7. Fluids
8. Heat Transfer
9. Thermodynamic cycles
10. Diesel and Otto cycles
11. Steam and Cooling cycles
12. Systems
Assignments for each topic (40%)
Final Assignment (60%)
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Bibliography and References
•Classes Slides and Readings•http://groups.google.pt/group/mit-portugal_ses_0910 •Books•http://www.lightandmatter.com/• Newton physics• Conservation laws• Vibration and Waves• Electricity and Magnetism•Optics•Modern Revolution in Physics•Internet•http://www.wikipedia.org/
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Tools for EngineeringCarlos A. Santos SilvaSeptember 25th, 2009
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International Measurement System (SI)
•Basic Units•Meter (m) for distance• The length between two marks on a platinum-iridium bar,
which was designed to represent 1⁄10,000,000 of the distance from the equator to the north pole through Paris• The meter is the length of the path travelled by light in
vacuum during a time interval of 1/299 792 458 of a second
• Second (s) for time• Kilogram (kg) for mass• Ampere (A) for electric current• Kelvin (K) for temperature•Mole (mol) for amount of substance in a system• Candela (cd) for luminous intensity Prototype kg
Prototype meter (1960)
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SI Prefixes
1000m 10n Prefix Symbol Since
10008 1024 yotta (iota) Y 1991
10007 1021 zetta (zeta) Z 1991
10006 1018 exa E 1975
10005 1015 peta P 1975
10004 1012 tera T 196010003 109 giga G 196010002 106 mega M 196010001 103 quilo k 1795
102 hecto h 1795101 deca da 1795
10000 100 none none10−1 deci d 179510−2 centi c 1795
1000-1 10−3 mili m 17951000-2 10−6 micro µ (mu)1 19601000-3 10−9 nano n 19601000-4 10−12 pico p 1960
1000-5 10−15 femto (fento) f 1964
1000-6 10−18 atto (ato) a 1964
1000-8 10−24 yocto (iocto) y 1991
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Metric Measurement System (SI)
•Countries where the metric system is official
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Other units
•Velocity – meter per second [m/s or ms-1]
• Velocity of an object traveling 1 m in 1 s
•Force – Newton [N]
• Force applied during 1 s to a 1kg object starting from rest to a velocity of 1ms-1
•Energy (Mechanical and thermal) – Joule [J]
• A force of 1 N moving an object for 1 m
• Heat 1g of air by 1 K
•Power – Watt [W]
• 1 J per 1 s / rate of work or energy
•Energy (Electrical) [J]
• Produce 1 W during 1 s
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Scientific notation
•It is used to represent large numbers
•Representing a number with a product between:
• a number between 1 and 10
• a number that is a power of 10.
•Examples:
• 1000 kg = 1x103 = 1E+3
• 1g = 0,001kg = 1x10-3 =1E-3
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Conversions
•Different measurement systems• 1 inch = 2,54 cm = 0,0254 = 2,54x10-2 m• 1 lb = 4,54 10-1 kg / 1kg = 2,2 lb• 1 cal = 4.184 J (thermochemical calorie)
•Conversion methodology• 10 pound in kg
• 1 year in s
g4540kg54,4kg2.2
10
pounds2.2
kg1pounds10pounds10
ss 7103,1531536000s
minute1
60
hour1
minutes60
day1
hours24
year1
days365year1year1
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Significant Figure
Gives the accuracy of a number• 5m ≈ 4,99m ≈ 5.12m• 5.00m ≠ 4.99m ≠ 5.12m
The number of significant digits depends on the least accurate data• 5.00m + 0.1m = 5.1m
To count the number of digits, count the number of digits different from the 0s to the left and to the right (ambiguous)• 50cm=5.0x10-1m or 5x10-1m• 0,5m=5x10-1m •Using scientific notation helps to keep track of the significant figures• 5x10-1m (1 significant figure)• 5.0x10-1m (2 significant figure)
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Scaling
•In order to study a system it is normal to make scaled models
Natural phenomena behave differently on different scales
Example
Clay 1: length x height x depth
Clay 2: 2length x 2height x 2depth
Why does Clay 2 break?
Cross Area α L2
Clay2 =4 Clay1
Volume (Weight) α L3
Clay2 =8 Clay1
Galileo experiment
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Order of Magnitude
•Things that differ by a factor of 10 are said to differ one order of magnitude
1 and 9 are the same order of magnitude
1 and 19 are one order of magnitude different
Often it is necessary to make rough estimates (~)
Round up to the nearest power of ten (same order of magnitude)
Don’t forget scaling effects:
Imagine simpler objects
Estimate area and volume based on linear dimensions
Example:
How much does it cost to cover the classroom floor with a 1m long square panels that cost 10€?
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Vector
Geometrical object described by•Magnitude (length)• Direction
Entity that “carries” A to B
Used to describe forces
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Vector Operations
Addition
Scalar multiplication
Cross Product