Hydroelectric Energy

Hydroelectric Energy

According to the United Nations, two thirds of the world's hydroelectric potential is being used, especially in North America and Europe. China is The world's largest producer ofhydroelectricity (95,000 MWinstalled), followed by the UnitedStates, Canada, and Brazil

SO; WHAT IS THE HYDROELECTRIC ENERGY?
SIMPLY; THE KINETIC ENERGY OF THE RIVERS IS TRANSFORMED INTO MECHANICAL ENERGY BY TURBINES THEN TRANSFORM THE MECHANICAL ENERGY INTO ELECTRICAL ENERGY.
SO WE NEED :

1-Turbine Room: The place where the kinetic energy of the rivers is transformed into mechanical energy by turbines and later into electrical energy by generators.
2-Generator: It transforms the mechanical energy of the turbines into electrical energy.

In brief :
1-Water enters the powerhouse under pressure and is injected into the turbine.
2-The force of the water on its blades causes the turbine to turn.
3-The turbine makes the generator turn, thereby producing electric energy. The water is returned to the river.
 

Plants :

1-Bypass Plant: Does not have a reservoir. It simply takes advantage of the available flow of water and thus is at the mercy of seasonal variations in water flow. It also cannot take advantage of occasional surplus water.

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2-Plants with Reservoirs: The presence of a reservoir, formed by a containment dam, guarantees a constant flow of water—and, therefore, of energy—independent of variations in water level.

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The water enters the powerhouse and turns the turbines. The generators produce electricity

For Pumping Plant it has also two reservoirs that In off-peak hours, thewater is pumped tothe first reservoir to be reused.

"Now about 20 percent of the world's electricity is generated by the force of rivers through the use of hydroelectric power plants. This technology, used since the 19th century, employs a renewable, nonpolluting resource, although the technology's impact on the environment is high."

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The Steam Engine

The Steam Engine

this external combustion engine, which transforms the energy in water vapor into mechanical work, was essential to the Industrial Revolution that took place in England in the 17th and 18th centuries. The history of its invention goes back to rudimentary devices without practical application and continues up to the invention of the steam engine by James Watt. The steam engine was of fundamental importance for industry and transportation, replacing beasts of burden, the mill, and even human laborers.

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How It Works :

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1-ASCENT

The pressure of the steam makes the piston rise .

2-DESCENT
Without heat, the steamcondenses, the pressuredisappears, and the piston falls.

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Watt's Innovation

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The Scottish engineering James Watt added a separate container where the steam condenses.

1- The valves allow steam to pass through either from the top or from the bottom.
2- The piston goes up or down according to the intake of the steam.
3- The steam expelled by the motion of the piston becomes liquid in the condenser.
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Applications of the Era
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Mainly in industry, mining, and transportation

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WATER EXTRACTION :
Basing his design on an earlier model, Thomas Savery in 1698 patented a steam engine that was used to extract water from mines. In 1712, Thomas Newcomen perfected it.
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SPINNING AND WEAVING :
It was used first to create spinning and weaving machines, and it was used later in printing presses.
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STERILIZATION :
About 1900, this model was built. It served, among other things, to sterilize water for nursing and for preparing medications.

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TRANSPORTATION :
In ships, cars, and locomotives. Some locomotivesreached speeds close to 36 miles per hour (58 km/h).

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GENERATING ELECTRICITY :
Currently this is one of the steam engine's most important uses.The steam is sent through a turbine, and its mechanical energy is transformed into electrical energy.

COMPOSITE MATERIALS REVOLUTIONISE AEROSPACE ENGINEERING - PT.1

COMPOSITE MATERIALS

REVOLUTIONISE AEROSPACE ENGINEERING

PT.1

Aerospace engineering is changing.  Aeroplanes have traditionally been made out of metal – usually alloys of aluminium; now however, engineers are increasingly working with carbon fibre composites.  Tim Edwards, a structural engineer at Atkins, describes the making of composite wings and the ztake-up of them across the aerospace industry.

 Airbus A400M, the next generation of military airlifter expected to make its first flight later this year,
has wings made from carbon fibre composite.  By using composites rather than metalsthe overall
strengthto weightratio of materialsused in aircraft design can improve by up to 20%

Fibrous composite materials were originally used in small quantities in military aircraft in the 1960s, and within civil aviation from the 1970s.  Bythe 1980s, composites were being used by civil aircraft manufacturers for a variety of secondary wing and tail components such as rudder and wing trailing edge panels.  However, it is with the advent of the latest generation of airliners, such as the Airbus A380, the world’s largest passenger aircraft, that these materials have been deployed extensively in primary load-carrying structure.  The A380 uses composite materials in its wings, which helps enable a 17% lower fuel use per passenger than comparable aircraft. 

LIGHTER, STRONGER

Composite materials (for aerospace uses, this is usually a carbon/epoxy mix) can provide a much better strength-to-weight ratio than metals: sometimes by as much as 20% better.  The lower weight results in lower fuel consumption and emissions and, because plastic structures need fewer riveted joints, enhanced aerodynamic efficiencies and lower manufacturing costs.  The aviation industry was, naturally, attracted by such benefits when composites first made an appearance, but it was the manufacturers of military aircraft who initially seized the opportunity to exploit their use to improve the speed and manoeuvrability of their products.  Civil aircraft manufacturers have been slower to implement them in their airframes for two reasons: stringent civil airworthiness requirements deterred the wholesale adoption of relatively unproven materials and the flat price of fuel in the late 1980s reduced the need for increased fuel efficiency in emerging airliner designs.Now, however, with extensive experience in the use of composites within the industry, and against the backdrop of European-wide targets to reduce emissions from aircraft, the value of realising the full potential of this important technology is clear. 

 

FATIGUE FREE

Carbon fibre reinforced plastic (CFRP) – carbon fibres embedded in an epoxy matrix – derives its high structural performance from the prodigious strength of the individual strands of carbon.  By way of comparison, the ultimate strength of aerospace grade aluminium alloys is typically 450 megapascals (MPa – a unit of stress or pressure, one MPa being about 10 times atmospheric pressure), whilst that of a carbon fibre would be five times that value.  As carbon composites are, additionally, only 60% of the density of aluminium, the potential for weight reduction in an airframe application is also apparent.  Glass, aramid and boron fibres are also used, but for primary load-bearing structure, carbon fibres have the best combinationof strength and cost.In addition to strength and weight, fibrous composites are thought to be virtually immune from ‘fatigue’.  Relatively small cracks in metal continue to growand it was this phenomenon of progressive cracking that saw the demise of the first de Havilland Comet design during the early jet age in the 1950s.  However, because of thestructure of composites – they are non-homogeneous – cracks will not be able to spread.  This means that structural engineers can perform design and analysis assuming much higher resistance to stress, and concernthemselves less with the long term durability of the structures they design. 

MANUFACTURING COMPOSITES

When applied to aircraft structures, carbon compositesare generally supplied in uni-directional (UD) form: thin (~0.125 – 0.25 mm thick) sheeor tapes of parallel fibres that have been pre-impregnated with resin that has yet to set.  This form of the material is ideal for the manufacture of thin plates that are used so extensively in airframe structures.  Manufacturers use tape-laying machines to lay down layers, or plies, of this material, one on top of the other, to form single piece sub-components.  By laying successive plies in different directions, the strength and stiffness of the component can be tailored to match the demands of the engineer, allowing adequate structural properties to be attained for minimum weight.  Modern tape-laying machines can fabricate an entire wing skin in one piece, eliminating the fasteners that are routinely used in metallic designs and thus saving manufacturing cost and further reducing overall weight.  To complete the manufacturing process, the component is cured within an autoclave, which subjects the component to pressure at an elevated temperature to consolidate and harden the layers of plies into a single monolith of carbon/epoxy laminate.

Source: Ingenia Magazine

Why did NASA decide to launch space shuttles from weather beaten Florida

Why did NASA decide to launch space shuttles

from weather beaten Florida

Florida was chosen as the starting point for U.S. manned missions— which began with the 1961 Project Mercury flights—for several reasons. One was that the location had to be on the coast, over the ocean, so falling debris or spent rocket boosters would not drop on inhabited places during ascent. The Atlantic coast is preferable because blasting off in an easterly direction allows the spacecraft to Harness the rotation of the earth rather than fighting against it, which saves a lot of fuel  for a rocket attempting to escape terrestrial gravity.

The second reason was that Florida is close to the equator, where the velocity of the earth’s spinning surface is the greatest.” The best launch site in the world right now is the spaceport that the European Space Agency has in French Guiana, about five degrees north of the equator”.

Merritt Island, where the Kennedy Space Center stands, already had good logistics when the spaceport was built. It had decent roads because there was already a navy and an army base nearby. But the population density was basically nonexistent, so you could build what you wanted. The U.S. did have lower-latitude options such as Puerto Rico and Hawaii, but those places are more difficult to reach, which may have diminished their appeal.

Last, it is important to remember that even though Florida has the turbulent climate of the subtropics; weather is an issue in most places. The middle of the country has Tornado Alley. In the South there are hurricanes. Wherever you go, there are always issues.

App. - Wind Energy

Wind Energy

Wind Energy
 

One of the most promising renewable energy resources is the use of wind to produce electricity by driving enormous wind turbines (windmills).

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App. - Roller Coasters

Roller Coasters

1912 : the year John Miller designed the first Under friction roller coaster

these colossal, twisted structures provide an exhilarating and frenetic ride. They wed technology to basic and seemingly incompatible emotions, such as panic, courage, fear, joy, vertigo, and amusement . 

Built as if to exclusively prove Newton's theories, the science of roller coasters abounds with all his terminology: acceleration, mass, gravity, movement, and inertia. But in all this, what is really thrilling is the free fall, the attraction of the abyss.

Safety Details :

The designers of these extreme machines take into account all possible safety factors to provide as safe an experience as possible.

Riders are made to wear safety belts, and machine parts are inspected on a regular basis to prevent accidents.

Joints and beams are X-rayed for flaws. Safety devices applied to the drive chain before cars reach the top prevent the train of cars from moving backward.

These devices are also installed on some of the hills, where the train slows down in its climb. In the event of wind gusts and sudden decelerations, these preventive measures keep the train in place and stop it from backtracking .

Wheels to keep the trolley on the track :

Three types of wheels are needed:

• Upper wheels to control the train for most of the route .
• Lower ones for use on the hills-G forces are sometimes greater than the weight of the train .
• Lateral wheels to prevent the train from derailing on curves.

Force of Gravity in Action :

Most of the motion in a roller-coaster ride is a response to the Earth's gravitational pull. No engines are mounted on the cars. After the train reaches the top of the first slope—the highest point on the ride— the train rolls downhill and gains speed under the Earth's gravitational pull. 

The speed is sufficient for it to climb over the next hill. This process occurs over and over again until all the train's energy has been lost to friction and the train of cars slows to a stop. If no energy were lost to friction, the train would be able to keep running as long as no point on the track was higher than the first peak.
 

1-POTENTIAL ENERGY

When the wagon reaches the highest point of the roller coaster, it has a great deal of potential energy.
 

2-MECHANICAL ENERGY

At a certain point in the trajectory, both energies (potential and kinetic) cancel each other out .
 

3-KINETIC ENERGY

is energy of motion that is, the energy released by the train every time it descends.

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Acceleration :

Powerpoint Presentation:

Structure is life - Pt.1

  To Download : Here