Due to their compact design, Wankel rotary engines have been installed in a variety of vehicles and devices including automobiles, motorcycles, racers, aircraft, go-karts, jet skis, snowmobiles, chain saws, and auxiliary power units.
Wednesday 30 January 2013
Wankel engine
Due to their compact design, Wankel rotary engines have been installed in a variety of vehicles and devices including automobiles, motorcycles, racers, aircraft, go-karts, jet skis, snowmobiles, chain saws, and auxiliary power units.
Advantages and Disadvantages of V-belt Drive over Flat Belt Drive
Following are the advantages and disadvantages of the V-belt drive over flat belt drive :-
Advantages:-
1. The V-belt drive gives compactness due to the small distance between centers of pulleys.
2. The drive is positive, because the slip between the belt and the pulley groove is negligible.
3. Since the V-belts are made endless and there is no joint trouble, therefore the drive is smooth.
4. It provides longer life, 3 to 5 years.
5. It can be easily installed and removed.
6. The operation of the belt and pulley is quiet.
7. The belts have the ability to cushion the shock when machines are started.
8. The high velocity ratio (maximum 10) may be obtained.
9. The wedging action of the belt in the groove gives high value of limiting *ratio of tensions.
Therefore the power transmitted by V-belts is more than flat belts for the same coefficient of
friction, arc of contact and allowable tension in the belts.
10. The V-belt may be operated in either direction, with tight side of the belt at the top or
bottom. The center line may be horizontal, vertical or inclined.
Disadvantages:-
1. The V-belt drive can not be used with large center distances, because of larger weight per
unit length.
2. The V-belts are not so durable as flat belts.
3. The construction of pulleys for V-belts is more complicated than pulleys of flat belts.
4. Since the V-belts are subjected to certain amount of creep, therefore these are not suitable
for constant speed applications such as synchronous machines and timing devices.
5. The belt life is greatly influenced with temperature changes, improper belt tension and
mismatching of belt lengths.
6. The centrifugal tension prevents the use of V-belts at speeds below 5 m/s and above 50 m/s.
Brakes
A brake is a mechanical device which inhibits motion.
Most commonly brakes use friction to convert kinetic energy into heat, though other methods of energy conversion may be employed. For example regenerative braking converts much of the energy to electrical energy, which may be stored for later use. Other methods convert kinetic energy into potential energy in such stored forms as pressurized air or pressurized oil.Still other braking methods even transform kinetic energy into different forms, for example by transferring the energy to a rotating flywheel.
Brakes may be broadly described as using friction, pumping, or electromagnetics.
1.Frictional brakes-Friction (pad/shoe) brakes are often rotating devices with a stationary pad and a rotating wear surface. Common configurations include shoes that contract to rub on the outside of a rotating drum, such as a band brake; a rotating drum with shoes that expand to rub the inside of a drum, commonly called a "drum brake", although other drum configurations are possible; and pads that pinch a rotating disc, commonly called a "disc brake".
2.Pumping brakes-Pumping brakes are often used where a pump is already part of the machinery.Pumping brakes can dump energy as heat, or can be regenerative brakes that recharge a pressure reservoir called a hydraulic accumulator.
3.Electromagnetic brakes-Electromagnetic brakes are likewise often used where an electric motor is already part of the machinery.Some diesel/electric railroad locomotives use the electric motors to generate electricity which is then sent to a resistor bank and dumped as heat. Some vehicles, such as some transit buses, do not already have an electric motor but use a secondary "retarder" brake that is effectively a generator with an internal short-circuit.
What Is Marine Engineering?
About a century ago no one would have heard about a marine engineer,but today it is a profession which is as established as any other famous ones. Over the last 100 years, engineering as a field of study has developed and diversified far beyond what could have been imagined prior to this period. Not only this, it has also branched out into various specialized fields that have achieved great progress. Most of these new fields are aligned to any of the basic engineering branches like mechanical, electrical, civil, electronics, computers etc and have something or the other incorporated from them. One such branch is called marine engineering.
Marine engineering is the branch of study that deals with the design, development, production and maintenance of the equipments used at sea and on board sea vessels like boats, ships etc. As a matter of fact, it is quite a vast field and it also has many sister arenas like naval architecture and nautical science. A marine enginee r is a professional who is responsible for the operation,maintenance and repair of all major mechanical and engineered equipments on board a ship. There are many mechanical systems that help in the operations of any vessel like the propulsion mechanics, electricity and power generation system, lubrication, fuel systems, water distillation, lighting and air conditioning system etc. These are all included in the technical responsibilities of a marine engineer.
A variety of marine programs, conducted by engineers also fall under this area of study, like an underwater vehicle research , cable laying work, renewable energy production in marine areas etc. In the latter half of the 19th century, marine engines for propulsion arrived and revolutionized the sea traveling vessels. It was about this time that the marine engineer began to stamp his importance over the scheme of work and transformedfrom a ‘stoker’ to an engineer. In recent years, there have been many new introductions to the marine technologies that have further enhanced the machines and the services like the fuel cells and magneto hydrodynamics etc. Furtherresearch and development is also in progress and newer details emerge every now and then. It would thus be safe to state that marine engineering is a very dynamic field.
In recent times, this field of study has caught on the imagination of many around the world. The interest shown by students of various countries and the response at the concerned departments in the universities bears testimony to this. The increase in the employment opportunities in this field has added to the lure of a job as a marine engineer. Both merchant navy and armed navy have immense opportunities for the students of thisfield. In addition to this, various manufacturing industries and units that produce shipping equipments and machines also hire these professionals to work in their production houses. Also, budding field jobs as trainers and teachers at various institutions are available andsuitable candidates are very much in demand. Judging by the developments and the interest it would not be wrong to assume that this field of study would continue to leave an indelible mark on the world.
Marine engineering is the branch of study that deals with the design, development, production and maintenance of the equipments used at sea and on board sea vessels like boats, ships etc. As a matter of fact, it is quite a vast field and it also has many sister arenas like naval architecture and nautical science. A marine enginee r is a professional who is responsible for the operation,maintenance and repair of all major mechanical and engineered equipments on board a ship. There are many mechanical systems that help in the operations of any vessel like the propulsion mechanics, electricity and power generation system, lubrication, fuel systems, water distillation, lighting and air conditioning system etc. These are all included in the technical responsibilities of a marine engineer.
A variety of marine programs, conducted by engineers also fall under this area of study, like an underwater vehicle research , cable laying work, renewable energy production in marine areas etc. In the latter half of the 19th century, marine engines for propulsion arrived and revolutionized the sea traveling vessels. It was about this time that the marine engineer began to stamp his importance over the scheme of work and transformedfrom a ‘stoker’ to an engineer. In recent years, there have been many new introductions to the marine technologies that have further enhanced the machines and the services like the fuel cells and magneto hydrodynamics etc. Furtherresearch and development is also in progress and newer details emerge every now and then. It would thus be safe to state that marine engineering is a very dynamic field.
In recent times, this field of study has caught on the imagination of many around the world. The interest shown by students of various countries and the response at the concerned departments in the universities bears testimony to this. The increase in the employment opportunities in this field has added to the lure of a job as a marine engineer. Both merchant navy and armed navy have immense opportunities for the students of thisfield. In addition to this, various manufacturing industries and units that produce shipping equipments and machines also hire these professionals to work in their production houses. Also, budding field jobs as trainers and teachers at various institutions are available andsuitable candidates are very much in demand. Judging by the developments and the interest it would not be wrong to assume that this field of study would continue to leave an indelible mark on the world.
ROTARY SCREW AIR COMPRESSOR
The gas compression process of a rotary screw is a continuous sweeping motion, so there is very little pulsation or surging of flow, as occurs with piston compressors.
Operations --->
Rotary screw compressors use two meshing helical screws, known as rotors, to compress the gas. In a dry running rotary screw compressor, timing gears ensure that the male and female rotors maintain precise alignment. In an oil-flooded rotary screw compressor, lubricating oil bridges the space between the rotors, both providing a hydraulic seal and transferring mechanical energy between the driving and driven rotor. Gas enters at the suction side and moves through the threads as the screws rotate. The meshing rotors force the gas through the compressor, and the gas exits at the end of the screws.
Advantages and Disadvantages of Chain Drive over Belt or Rope Drive
Advantages:-
1.As no slip takes place during chain drive, hence perfect velocity ratio is obtained.
2.Since the chains are made of metal, therefore they occupy less space in width than a belt or
rope drive.
3.It may be used for both long as well as short distances.
4.It gives a high transmission efficiency (upto 98 percent).
5.It gives less load on the shafts.
6.It has the ability to transmit motion to several shafts by one chain only.
7.It transmits more power than belts.
8.It permits high speed ratio of 8 to 10 in one step.
9.It can be operated under adverse temperature and atmospheric conditions.
Disadvantages:-
1.The production cost of chains is relatively high.
2.The chain drive needs accurate mounting and careful maintenance, particularly lubrication
and slack adjustment.
3.The chain drive has velocity fluctuations especially when unduly stretched.
Monday 28 January 2013
Glow Plug
A glowplug (alternatively spelled as glow plug or glow-plug) is a heating device used to aid starting diesel engines. The glow plug is a pencil-shaped piece of metal with a heating element at the tip. This heating element, when electrified, heats due to its electrical resistance and begins to emit light in the visible spectrum, hence the term "glow" plug. The effect is very similar to that of a toaster. Heat generated by the glowplugs is directed into the cylinders, and serves to warm the engine block immediately surrounding the cylinders. This aids in reducing the amount of thermal diffusion which will occur when the engine attempts to start.
BOILER
A boiler is a closed vessel in which water or other fluid is heated. The heated or vaporized fluid exits the boiler for use in various processes or heating applications,including boiler-based power generation, cooking, and sanitation.
The pressure vessel in a boiler is usually made of steel (or alloy steel), or historically of wrought iron. Stainless steel is virtually prohibited (by the ASME Boiler Code) for use in wetted parts of modern boilers, but is used often in superheater sections that will not be exposed to liquid boiler water.Cast iron may be used for the heating vessel of domestic water heaters. Although such heaters are usually termed "boilers" in some countries, their purpose is usually to produce hot water, not steam, and so they run at low pressure and try to avoid actual boiling. The brittleness of cast iron makes it impractical for high pressure steam boilers.
The source of heat for a boiler is combustion of any of several fuels, such as wood, coal, oil, or natural gas. Electric steam boilers use resistance- or immersion-type heating elements.
DTS-Si Technology
As common biker or as laymen we keep hearing that so and so bike features what is called DTS-Si technology, but we hardly understand what it means except being familiar with the term maybe through the commercials/advertisements.
Well, the DTS-Si or the Digital Twin Spark-Swirl Induction is a technology where dual spark plugs are used and that it is known to give great mileage to the bikes and this is main purpose why the major bike manufacturers use the technology in their bikes. The DTS-Si technology will likely give unbelievable fuel efficiency provided the bike runs in standard test conditions.
Generally, the 100cc motorbikes do not offer such a mileage but the DTS-Si technology powered bikes give a greater mileage, which is the biggest advantage for the bikes. As the technology uses 2 spark plugs to initiate the combustion of air-fuel mixture, it leaves little unburnt fuel within the engine.
Why is the DTS-Si technology better than the conventional single spark plug equipped engine?
Apart from giving an amazing mileage to the bike, the engine enabled with DTS-Si technology does not compromise on technology. In a traditional single spark plug oriented the combustion process is very slow. This is because the spark plug is located at one end of the combustion chamber, which sparks the air-fuel mixture and the flame inflates like a balloon that takes some time to reach the remote corner of the combustion chamber that delays the combustion process. Whereas, in the DTS-Si technology equipped engine the cylinder head is fitted with two spark plugs at two of corners of the combustion chamber, which ensures that the sparks emit from two ends of the chamber and the air fuel mixture ignites to produce two flame fronts thus, the process of combustion is faster and also the pressure rises at a good pace. This technology in the engine promotes greater torque, fuel-efficiency and low emission.
The Hot Bulb Engine
The hot bulb engine, or hotbulb or heavy oil engine is a type of internal combustion engine. It is an engine in which fuel is ignited by being brought into contact with a red-hot metal surface inside a bulb followed by the introduction of air (oxygen) compressed into the hot bulb chamber by the rising piston. There is some ignition when the fuel is introduced but it quickly uses up the available oxygen in the bulb. Vigorous ignition takes place only when sufficient oxygen is supplied to the hot bulb chamber on the compression stroke of the engine.
Most hot bulb engines were produced as one-cylinder low-speed two-stroke crankcase scavenging units.
Parts:
1) Hot Bulb
2)Cylinder
3)Piston
4)Cranckcase
Advantages of Wire Ropes:-
The wire ropes have the following advantages as compared to fibre ropes.
1. These are lighter in weight,
2. These offer silent operation,
3. These can withstand shock loads,
4. These are more reliable,
5. These are more durable,
6. They do not fail suddenly,
7. The efficiency is high, and
8. The cost is low.
Sunday 27 January 2013
Worm drive
A worm drive is a gear arrangement in which a worm (which is a gear in the form of a screw) meshes with a worm gear (which is similar in appearance to a spur gear, and is also called a worm wheel).Like other gear arrangements, a worm drive can reduce rotational speed or allow higher torque to be transmitted. Unlike with ordinary gear trains, the direction of transmission (input shaft vs output shaft) is not reversible when using large reduction ratios, due to the greater friction involved between the worm and worm-wheel, when usually a single start (one spiral) worm is used
Worm drives are used in presses, in rolling mills, in conveying engineering, in mining industry machines, and on rudders. In addition, milling heads and rotary tables are positioned using high-precision duplex worm drives with adjustable backlash. Worm gears are used on many lift- (in US English known as elevator) and escalator-drive applications due to their compact size and the non-reversibility of the gear.
Saturday 26 January 2013
Durability Analysis | Application Of Durability Analysis In Automotive, Aerospace & Wind Turbines
Automotive
Design more reliable transmissions, drivelines and axles
View the whole gearbox as an interacting and flexible system
Predict gear, bearing and shaft life-times in the design concept phase
Accurately and efficiently compare complex gearbox arrangements or concepts such as AMT, DCT, Hybrid and CVT
Reduce gearbox weight by using component strength
Minimize noise and vibration by influencing the transmission error
Identify the weak points in the whole system under realistic load conditions
Consider the impact of manufacturing tolerances in the concept design phase
Improve the bearing choice by unique accurate prediction of bearing behavior
Interact with dynamic solutions for your full vehicle design
Predict the affects of generators/e-engines on the gears and its components in your hybrid system
Wind turbine
Understand and benchmark operating load and extreme load scenarios
Design gearboxes to meet life-time targets
View the gearbox as one complete system, without the need for sectioning and sectional boundary conditions
Analyze the behavior of complex planetary systems within the whole system
Accurately predict loads, deflections and interactions of all components
Calculate detailed bearing behavior to identify excessive loads
Direct loads or reduce misalignments to improve the system quality
Predict load sharing in the fully flexible system instead of assuming load sharing factors
Reduce weight and cost without reducing component lifetime
Minimize noise pollution caused by transmission error
Aerospace
Improve reliability for critical parts
Reduce gearbox weight
Predict bearing behavior under extreme load and climate conditions
Optimize gearbox size
Off-highway
Design heavy duty transmissions
Accurately represent multi-gear mesh situations
Optimize gearbox weight without compromising durability
Predict system behavior under misuse conditions
Compare different lubrication situations
Precisely define micro-geometries to avoid edge-loading of teeth under extreme load conditions
Consider split-torque system load
Industrial equipment
Design for improved reliability in process machinery, material handling, power take offs, speed reducers and production line equipment
Improve accuracy of high precision machinery by understanding and predicting system and component deflections
Reduce failures in gears and bearings due to precise prediction of misalignments
Consumer and office appliance
Optimize weight and size of power tools, food processors, washing machines, printers and photocopiers
Improve product quality by reducing unwanted deflections
Predict changes of working accuracy over a product’s life
Design casings that fulfill the requests for look and function simultaneously without wasting material
Consider new materials for new or existing product concepts
Create technical documentation for certification
Design more reliable transmissions, drivelines and axles
View the whole gearbox as an interacting and flexible system
Predict gear, bearing and shaft life-times in the design concept phase
Accurately and efficiently compare complex gearbox arrangements or concepts such as AMT, DCT, Hybrid and CVT
Reduce gearbox weight by using component strength
Minimize noise and vibration by influencing the transmission error
Identify the weak points in the whole system under realistic load conditions
Consider the impact of manufacturing tolerances in the concept design phase
Improve the bearing choice by unique accurate prediction of bearing behavior
Interact with dynamic solutions for your full vehicle design
Predict the affects of generators/e-engines on the gears and its components in your hybrid system
Wind turbine
Understand and benchmark operating load and extreme load scenarios
Design gearboxes to meet life-time targets
View the gearbox as one complete system, without the need for sectioning and sectional boundary conditions
Analyze the behavior of complex planetary systems within the whole system
Accurately predict loads, deflections and interactions of all components
Calculate detailed bearing behavior to identify excessive loads
Direct loads or reduce misalignments to improve the system quality
Predict load sharing in the fully flexible system instead of assuming load sharing factors
Reduce weight and cost without reducing component lifetime
Minimize noise pollution caused by transmission error
Aerospace
Improve reliability for critical parts
Reduce gearbox weight
Predict bearing behavior under extreme load and climate conditions
Optimize gearbox size
Off-highway
Design heavy duty transmissions
Accurately represent multi-gear mesh situations
Optimize gearbox weight without compromising durability
Predict system behavior under misuse conditions
Compare different lubrication situations
Precisely define micro-geometries to avoid edge-loading of teeth under extreme load conditions
Consider split-torque system load
Industrial equipment
Design for improved reliability in process machinery, material handling, power take offs, speed reducers and production line equipment
Improve accuracy of high precision machinery by understanding and predicting system and component deflections
Reduce failures in gears and bearings due to precise prediction of misalignments
Consumer and office appliance
Optimize weight and size of power tools, food processors, washing machines, printers and photocopiers
Improve product quality by reducing unwanted deflections
Predict changes of working accuracy over a product’s life
Design casings that fulfill the requests for look and function simultaneously without wasting material
Consider new materials for new or existing product concepts
Create technical documentation for certification
Friday 25 January 2013
Casting Inspection | Non Destructive Testing | Destructive Testing
Inspection of Castings:
A large number of methods have been developed to inspect castings for defects that may occur during their production. Such inspections may be in process inspections or finished product inspections.
In process inspections are carried out before a lot of castings have been completed to detect any flaws that may have occurred in the process so that corrective measures can be taken to remove the defect in the remaining units. Finished product inspections are carried out after the castings have all been completed to make sure that the product meets the requirements specified by the customer.
Defective castings may be salvaged or completely rejected to be re-melted for their material content depending upon the nature and extent of defect. The inspection methods may also be divided into destructive or non-destructive categories depending upon the magnitude of damage done to the casting during inspection. Destructive methods generally relate to sawing or breaking off of parts of the castings at places where voids or internal defects are suspected. Castings may also be damaged during strength tests.
Destructive tests suffer from the disadvantage that the saw cuts may miss the flaw or the sample may not represent the behavior of the entire lot. Because of these reasons non-destructive tests are generally more commonly relied upon than destructive tests.
Some of the prominent non destructive methods are described below:
Visual Inspection:
It consists of inspecting the surface of the casting with naked eye or sometimes with a magnifying glass or microscope. It can only indicate surface defects such as blow holes, fusion, swells, external cracks, and mismatch. Almost all castings are subjected to certain degree of visual inspection.
Dimensional Inspection:
Dimensional inspection is carried out to make sure that the castings produced have the required overall dimensions including allowances for machining. It may sometimes be necessary to break a part of the casting to take measurements of inside dimensions.
Sound Test:
This is a rough test to indicate a flaw or discontinuity in a casting. The casting is suspended from a suitable support free of all obstructions and tapped at various places on its surface with a small hammer. Any change in the tone produced indicates the existence of a flaw. The method cannot indicate the exact location and extent of the discontinuity.
Impact Test:
In this test the casting is subjected to a blow from a hammer of known weight striking or falling on the casting. Defective castings fail under the impact of the blow but the method is very crude and unreliable.
Pressure Test:
This test is carried out on castings required to be leak proof. All openings of the castings are closed and a gas or fluid under pressure is introduced in it. Castings having porosity leak under this pressure. The leakage may be detected by submerging the casting in a water tank or using a soap film if the pressure is applied by compressed air. If a liquid is used for applying pressure the leakage can be found by visual inspection.
Radiography:
Radiography uses X-rays or gamma rays penetrating through the castings and giving a shadow picture on a photographic film placed behind the work piece. These rays have very short wave length of the order of 0.001 Angstrom (10-10m) units to 40 Angstrom units for x-rays and 0.005 to about 3 Angstrom units for gamma rays compared to about 5500 Angstrom units for the centre of the visible spectrum.
The ability of these waves to penetrate through metal depends also on the density of the metal and as such they can penetrate more easily in places where there is less metal that those where more metal is present leading to a shadow picture formation on the film. Any defects in the casting can easily be identified from this picture. Because of their shorter wave length gamma rays have a better penetration through the metal and are more commonly used.
Magnetic Particle Testing:
This test is used for detecting cracks in metals like cast iron and steel which can be magnetized. For carrying out the test the casting is magnetized and then fine particles of iron or steel are spread on its surface. Presence of a crack or void in the casting results in interruption of the magnetic field and leakage of magnetic flux at the place of the crack.
The particles of iron or steel spread on the casting surface are held by this leaking flux giving a visual indication of the nature and extent of crack. Very small cracks or voids at or near the surface which may not even be detected by radiography are easily revealed by this method.
Penetrant Testing:
This method also is used for detecting very small surface cracks and has the advantage over the magnetic particle method that it can be used for any material. The parts to be tested are either dipped into or covered with a penetrant testing liquid which has very good wetting and penetrating ability. The liquid is drawn into the cracks or voids by capillary action.
After the penetrant has been applied to the surface to be tested extra penetrant is wiped off the surface is dried and a developer applied to it. This developer helps in drawing out the penetrant so that it becomes visible on the surface. The penetrant liquids often contain materials which fluoresce under ultraviolet light or a die to indicate their presence.
Ultrasonic Testing:
Ultrasonic testing is used to detect defects like cracks, voids or porosity within the interior of the casting. The method uses reflection and transmission of high frequency sound waves. Ultrasonic sound waves much higher than the audible range are produced and made to pass through the casting.
The time interval between the transmitted ray and reflected ray is recorded by a cathode ray oscilloscope. Any crack or void in the casting results in reflection or some of the sound from the crack which appears as a pip between the two pips representing the thickness of the casting. The depth of the crack from the surface of the casting can be easily calculated from the distance between these pips.
A large number of methods have been developed to inspect castings for defects that may occur during their production. Such inspections may be in process inspections or finished product inspections.
In process inspections are carried out before a lot of castings have been completed to detect any flaws that may have occurred in the process so that corrective measures can be taken to remove the defect in the remaining units. Finished product inspections are carried out after the castings have all been completed to make sure that the product meets the requirements specified by the customer.
Defective castings may be salvaged or completely rejected to be re-melted for their material content depending upon the nature and extent of defect. The inspection methods may also be divided into destructive or non-destructive categories depending upon the magnitude of damage done to the casting during inspection. Destructive methods generally relate to sawing or breaking off of parts of the castings at places where voids or internal defects are suspected. Castings may also be damaged during strength tests.
Destructive tests suffer from the disadvantage that the saw cuts may miss the flaw or the sample may not represent the behavior of the entire lot. Because of these reasons non-destructive tests are generally more commonly relied upon than destructive tests.
Some of the prominent non destructive methods are described below:
Visual Inspection:
It consists of inspecting the surface of the casting with naked eye or sometimes with a magnifying glass or microscope. It can only indicate surface defects such as blow holes, fusion, swells, external cracks, and mismatch. Almost all castings are subjected to certain degree of visual inspection.
Dimensional Inspection:
Dimensional inspection is carried out to make sure that the castings produced have the required overall dimensions including allowances for machining. It may sometimes be necessary to break a part of the casting to take measurements of inside dimensions.
Sound Test:
This is a rough test to indicate a flaw or discontinuity in a casting. The casting is suspended from a suitable support free of all obstructions and tapped at various places on its surface with a small hammer. Any change in the tone produced indicates the existence of a flaw. The method cannot indicate the exact location and extent of the discontinuity.
Impact Test:
In this test the casting is subjected to a blow from a hammer of known weight striking or falling on the casting. Defective castings fail under the impact of the blow but the method is very crude and unreliable.
Pressure Test:
This test is carried out on castings required to be leak proof. All openings of the castings are closed and a gas or fluid under pressure is introduced in it. Castings having porosity leak under this pressure. The leakage may be detected by submerging the casting in a water tank or using a soap film if the pressure is applied by compressed air. If a liquid is used for applying pressure the leakage can be found by visual inspection.
Radiography:
Radiography uses X-rays or gamma rays penetrating through the castings and giving a shadow picture on a photographic film placed behind the work piece. These rays have very short wave length of the order of 0.001 Angstrom (10-10m) units to 40 Angstrom units for x-rays and 0.005 to about 3 Angstrom units for gamma rays compared to about 5500 Angstrom units for the centre of the visible spectrum.
The ability of these waves to penetrate through metal depends also on the density of the metal and as such they can penetrate more easily in places where there is less metal that those where more metal is present leading to a shadow picture formation on the film. Any defects in the casting can easily be identified from this picture. Because of their shorter wave length gamma rays have a better penetration through the metal and are more commonly used.
Magnetic Particle Testing:
This test is used for detecting cracks in metals like cast iron and steel which can be magnetized. For carrying out the test the casting is magnetized and then fine particles of iron or steel are spread on its surface. Presence of a crack or void in the casting results in interruption of the magnetic field and leakage of magnetic flux at the place of the crack.
The particles of iron or steel spread on the casting surface are held by this leaking flux giving a visual indication of the nature and extent of crack. Very small cracks or voids at or near the surface which may not even be detected by radiography are easily revealed by this method.
Penetrant Testing:
This method also is used for detecting very small surface cracks and has the advantage over the magnetic particle method that it can be used for any material. The parts to be tested are either dipped into or covered with a penetrant testing liquid which has very good wetting and penetrating ability. The liquid is drawn into the cracks or voids by capillary action.
After the penetrant has been applied to the surface to be tested extra penetrant is wiped off the surface is dried and a developer applied to it. This developer helps in drawing out the penetrant so that it becomes visible on the surface. The penetrant liquids often contain materials which fluoresce under ultraviolet light or a die to indicate their presence.
Ultrasonic Testing:
Ultrasonic testing is used to detect defects like cracks, voids or porosity within the interior of the casting. The method uses reflection and transmission of high frequency sound waves. Ultrasonic sound waves much higher than the audible range are produced and made to pass through the casting.
Artificial Leaf Solar Power | Artificial Leaf Produce Electricity
Photosynthesis:
Photosynthesis is the process by which plants, some bacteria, and some protists use the energy from sunlight to produce sugar, which cellular respiration converts into ATP, the “fuel” used by all living things. The conversion of unusable sunlight energy into usable chemical energy, is associated with the actions of the green pigment chlorophyll.
They release molecular oxygen and remove CO2 (Carbon Dioxide) from the air.
ATP: Adenosine Tri-Phosphate (ATP) Here the energy is stored in living systems; it consists of a Nucleotide (with Ribose sugar) with Three Phosphate groups.
Why is photosynthesis important:
Nearly all living things depend on the energy produced from photosynthesis for their nourishment. Animals need the plants for food as well as oxygen. Only green plants are able to change light energy into chemical energy stored in food, thus they are vital to life on Earth.
Solar cells:
Conventional solar cells are also called as Photo Voltaic Cells. These cells are made out of semiconducting material, usually silicon. When light hits the cells, they absorb energy though photons. This absorbed energy knocks out electrons in the silicon, allowing them to flow. By adding different impurities to the silicon such as phosphorus or boron, an electric field can be established. This electric field acts as a diode, because it only allows electrons to flow in one direction. Consequently, the end result is a current of electrons, better known to us as electricity.
Drawbacks of Solar cells:
They can only achieve efficiencies around 10% and they are expensive to manufacture. The first drawback, inefficiency, is almost unavoidable with silicon cells. This is because the incoming photons, or light, must have the right energy, called the band gap energy, to knock out an electron. If the photon has less energy than the band gap energy then it will pass through. If it has more energy than the band gap, then that extra energy will be wasted as heat.
Artificial Leaf:
Mixing of Photosynthesis + Conventional Solar Cells + Hydrogen Fuel Cell
This Leaf device combines a commercially available solar cell (Silicon) with a pair of inexpensive catalysts made of Cobalt and Nickel that split water into Oxygen and Hydrogen. The hydrogen can be stored and used as an energy source. (For example to power a fuel cell).
The collection and storage of the sun’s energy as hydrogen fuel is a key step in overcoming one of the limitations of solar power — it generates energy when the sun is shining, but it needs to be stored somewhere to be useful at night and in cloudy weather. Batteries are one place to store the energy, but it is limited. Storing solar energy as hydrogen fuel could be an answer for producing the electricity continuously.
Using this approach, a solar panel roughly one square meter bathed in water could produce enough hydrogen to supply electricity for a house.
Thursday 24 January 2013
GATE Syllabus – Mechanical Engineering
Syllabus for Mechanical Engineering
ME-Mechanical Engineering
ENGINEERING MATHEMATICS
Linear Algebra:
Matrix algebra, Systems of linear equations, Eigen values and eigen vectors.
Calculus:
Functions of single variable, Limit, continuity and differentiability, Mean value theorems, Evaluation of definite and improper integrals, Partial derivatives, Total derivative, Maxima and minima, Gradient, Divergence and Curl, Vector identities, Directional derivatives, Line, Surface and Volume integrals, Stokes, Gauss and Green’s theorems.
Differential equations:
First order equations (linear and nonlinear), Higher order linear differential equations with constant coefficients, Cauchy’s and Euler’s equations, Initial and boundary value problems, Laplace transforms, Solutions of one dimensional heat and wave equations and Laplace equation.
Complex variables:
Analytic functions, Cauchy’s integral theorem, Taylor and Laurent series. Probability and Statistics: Definitions of probability and sampling theorems, Conditional probability, Mean, median, mode and standard deviation, Random variables, Poisson, Normal and Binomial distributions.
Numerical Methods:
Numerical solutions of linear and non-linear algebraic equations Integration by trapezoidal and Simpson’s rule, single and multi-step methods for differential equations.
APPLIED MECHANICS AND DESIGN
Engineering Mechanics:
Free body diagrams and equilibrium; trusses and frames; virtual work; kinematics and dynamics of particles and of rigid bodies in plane motion, including impulse and momentum (linear and angular) and energy formulations; impact.
Strength of Materials:
Stress and strain, stress-strain relationship and elastic constants, Mohr’s circle for plane stress and plane strain, thin cylinders; shear force and bending moment diagrams; bending and shear stresses; deflection of beams; torsion of circular shafts; Euler’s theory of columns; strain energy methods; thermal stresses.
Theory of Machines:
Displacement, velocity and acceleration analysis of plane mechanisms; dynamic analysis of slider-crank mechanism; gear trains; flywheels.
Vibrations:
Free and forced vibration of single degree of freedom systems; effect of damping; vibration isolation; resonance, critical speeds of shafts.
Design:
Design for static and dynamic loading; failure theories; fatigue strength and the S-N diagram; principles of the design of machine elements such as bolted, riveted and welded joints, shafts, spur gears, rolling and sliding contact bearings, brakes and clutches.
FLUID MECHANICS AND THERMAL SCIENCES
Fluid Mechanics:
Fluid properties; fluid statics, manometry, buoyancy; control-volume analysis of mass, momentum and energy; fluid acceleration; differential equations of continuity and momentum; Bernoulli’s equation; viscous flow of incompressible fluids; boundary layer; elementary turbulent flow; flow through pipes, head losses in pipes, bends etc.
Heat-Transfer:
Modes of heat transfer; one dimensional heat conduction, resistance concept, electrical analogy, unsteady heat conduction, fins; dimensionless parameters in free and forced convective heat transfer, various correlations for heat transfer in flow over flat plates and through pipes; thermal boundary layer; effect of turbulence; radiative heat transfer, black and grey surfaces, shape factors, network analysis; heat exchanger performance, LMTD and NTU methods.
Thermodynamics: Zeroth, First and Second laws of thermodynamics; thermodynamic system and processes; Carnot cycle. irreversibility and availability; behaviour of ideal and real gases, properties of pure substances, calculation of work and heat in ideal processes; analysis of thermodynamic cycles related to energy conversion.
Applications:
Power Engineering:
Steam Tables, Rankine, Brayton cycles with regeneration and reheat. I.C. Engines: air-standard Otto, Diesel cycles. Refrigeration and air-conditioning: Vapour refrigeration cycle, heat pumps, gas refrigeration, Reverse Brayton cycle; moist air: psychrometric chart, basic psychrometric processes. Turbomachinery: Pelton-wheel, Francis and Kaplan turbines — impulse and reaction principles, velocity diagrams.
MANUFACTURING AND INDUSTRIAL ENGINEERING
Engineering Materials:
Structure and properties of engineering materials, heat treatment, stressstrain diagrams for engineering materials.
Metal Casting:
Design of patterns, moulds and cores; solidification and cooling; riser and gating design, design considerations.
Forming:
Plastic deformation and yield criteria; fundamentals of hot and cold working processes; load estimation for bulk (forging, rolling, extrusion, drawing) and sheet (shearing, deep drawing, bending) metal forming processes; principles of powder metallurgy.
Joining:
Physics of welding, brazing and soldering; adhesive bonding; design considerations in welding.
Machining and Machine Tool Operations:
Mechanics of machining, single and multi-point cutting tools, tool geometry and materials, tool life and wear; economics of machining; principles of non-traditional machining processes; principles of work holding, principles of design of jigs and fixtures
Metrology and Inspection:
Limits, fits and tolerances; linear and angular measurements; comparators; gauge design; interferometry; form and finish measurement; alignment and testing methods; tolerance analysis in manufacturing and assembly.
Computer Integrated Manufacturing:
Basic concepts of CAD/CAM and their integration tools.
Production Planning and Control:
Forecasting models, aggregate production planning, scheduling, materials requirement planning.
Inventory Control:
Deterministic and probabilistic models; safety stock inventory control systems.
Operations Research:
Linear programming, simplex and duplex method, transportation, assignment, network flow models, simple queuing models, PERT and CPM.
ME-Mechanical Engineering
ENGINEERING MATHEMATICS
Linear Algebra:
Matrix algebra, Systems of linear equations, Eigen values and eigen vectors.
Calculus:
Functions of single variable, Limit, continuity and differentiability, Mean value theorems, Evaluation of definite and improper integrals, Partial derivatives, Total derivative, Maxima and minima, Gradient, Divergence and Curl, Vector identities, Directional derivatives, Line, Surface and Volume integrals, Stokes, Gauss and Green’s theorems.
Differential equations:
First order equations (linear and nonlinear), Higher order linear differential equations with constant coefficients, Cauchy’s and Euler’s equations, Initial and boundary value problems, Laplace transforms, Solutions of one dimensional heat and wave equations and Laplace equation.
Complex variables:
Analytic functions, Cauchy’s integral theorem, Taylor and Laurent series. Probability and Statistics: Definitions of probability and sampling theorems, Conditional probability, Mean, median, mode and standard deviation, Random variables, Poisson, Normal and Binomial distributions.
Numerical Methods:
Numerical solutions of linear and non-linear algebraic equations Integration by trapezoidal and Simpson’s rule, single and multi-step methods for differential equations.
APPLIED MECHANICS AND DESIGN
Engineering Mechanics:
Free body diagrams and equilibrium; trusses and frames; virtual work; kinematics and dynamics of particles and of rigid bodies in plane motion, including impulse and momentum (linear and angular) and energy formulations; impact.
Strength of Materials:
Stress and strain, stress-strain relationship and elastic constants, Mohr’s circle for plane stress and plane strain, thin cylinders; shear force and bending moment diagrams; bending and shear stresses; deflection of beams; torsion of circular shafts; Euler’s theory of columns; strain energy methods; thermal stresses.
Theory of Machines:
Displacement, velocity and acceleration analysis of plane mechanisms; dynamic analysis of slider-crank mechanism; gear trains; flywheels.
Vibrations:
Free and forced vibration of single degree of freedom systems; effect of damping; vibration isolation; resonance, critical speeds of shafts.
Design:
Design for static and dynamic loading; failure theories; fatigue strength and the S-N diagram; principles of the design of machine elements such as bolted, riveted and welded joints, shafts, spur gears, rolling and sliding contact bearings, brakes and clutches.
FLUID MECHANICS AND THERMAL SCIENCES
Fluid Mechanics:
Fluid properties; fluid statics, manometry, buoyancy; control-volume analysis of mass, momentum and energy; fluid acceleration; differential equations of continuity and momentum; Bernoulli’s equation; viscous flow of incompressible fluids; boundary layer; elementary turbulent flow; flow through pipes, head losses in pipes, bends etc.
Heat-Transfer:
Modes of heat transfer; one dimensional heat conduction, resistance concept, electrical analogy, unsteady heat conduction, fins; dimensionless parameters in free and forced convective heat transfer, various correlations for heat transfer in flow over flat plates and through pipes; thermal boundary layer; effect of turbulence; radiative heat transfer, black and grey surfaces, shape factors, network analysis; heat exchanger performance, LMTD and NTU methods.
Thermodynamics: Zeroth, First and Second laws of thermodynamics; thermodynamic system and processes; Carnot cycle. irreversibility and availability; behaviour of ideal and real gases, properties of pure substances, calculation of work and heat in ideal processes; analysis of thermodynamic cycles related to energy conversion.
Applications:
Power Engineering:
Steam Tables, Rankine, Brayton cycles with regeneration and reheat. I.C. Engines: air-standard Otto, Diesel cycles. Refrigeration and air-conditioning: Vapour refrigeration cycle, heat pumps, gas refrigeration, Reverse Brayton cycle; moist air: psychrometric chart, basic psychrometric processes. Turbomachinery: Pelton-wheel, Francis and Kaplan turbines — impulse and reaction principles, velocity diagrams.
MANUFACTURING AND INDUSTRIAL ENGINEERING
Engineering Materials:
Structure and properties of engineering materials, heat treatment, stressstrain diagrams for engineering materials.
Metal Casting:
Design of patterns, moulds and cores; solidification and cooling; riser and gating design, design considerations.
Forming:
Plastic deformation and yield criteria; fundamentals of hot and cold working processes; load estimation for bulk (forging, rolling, extrusion, drawing) and sheet (shearing, deep drawing, bending) metal forming processes; principles of powder metallurgy.
Joining:
Physics of welding, brazing and soldering; adhesive bonding; design considerations in welding.
Machining and Machine Tool Operations:
Mechanics of machining, single and multi-point cutting tools, tool geometry and materials, tool life and wear; economics of machining; principles of non-traditional machining processes; principles of work holding, principles of design of jigs and fixtures
Metrology and Inspection:
Limits, fits and tolerances; linear and angular measurements; comparators; gauge design; interferometry; form and finish measurement; alignment and testing methods; tolerance analysis in manufacturing and assembly.
Computer Integrated Manufacturing:
Basic concepts of CAD/CAM and their integration tools.
Production Planning and Control:
Forecasting models, aggregate production planning, scheduling, materials requirement planning.
Inventory Control:
Deterministic and probabilistic models; safety stock inventory control systems.
Operations Research:
Linear programming, simplex and duplex method, transportation, assignment, network flow models, simple queuing models, PERT and CPM.
Why GATE
The M.E/M.Tech/M.S experience at IISc & IIT’s…..
True essence of being an engineer or having engineering degree
Emphasis on research & development.
Advanced engineering concepts through world class faculties.
A gateway to extensive practical exercises, various case studies, simulation & modeling of real life problems, individual and group projects, research publications/presentations in journals/conferences etc.
Highly competitive environment (best brains in the country), develops & broadens intellectual thought process.
The M.E/M.Tech advantage……
Better and more satisfying job profile
Earn while you learn: financial scholarships (a minimum of 8000/- INR per month).
Higher salary offered as compared to B.E/B.Tech.
Eligibility criteria to apply for faculty/research positions in educational/R&D centers
Mandatory qualification even for self financing students to post graduate programs
Have an edge over peers: Awards technical certification.
Accepted in University of Singapore.
Increasing trend among PSU’s making GATE score as an eligibility criteria for job application.
True essence of being an engineer or having engineering degree
Emphasis on research & development.
Advanced engineering concepts through world class faculties.
A gateway to extensive practical exercises, various case studies, simulation & modeling of real life problems, individual and group projects, research publications/presentations in journals/conferences etc.
Highly competitive environment (best brains in the country), develops & broadens intellectual thought process.
The M.E/M.Tech advantage……
Better and more satisfying job profile
Earn while you learn: financial scholarships (a minimum of 8000/- INR per month).
Higher salary offered as compared to B.E/B.Tech.
Eligibility criteria to apply for faculty/research positions in educational/R&D centers
Mandatory qualification even for self financing students to post graduate programs
Have an edge over peers: Awards technical certification.
Accepted in University of Singapore.
Increasing trend among PSU’s making GATE score as an eligibility criteria for job application.
About GATE
Graduate Aptitude Test in Engineering (GATE) is an all India examination administered and conducted jointly by the Indian Institute of Science and seven Indian Institutes of Technology on behalf of the National Coordination Board – GATE, Department of Higher Education, Ministry of Human Resource Development (MHRD), Government of India.
The GATE committee, which comprises of representatives from the administering institutes, is the sole authority for regulating the examination and declaring the results.
GATE is conducted through the constitution of eight zones. The zones and the corresponding administrative institutes are:
Zone-1: Indian Institute of Science Bangalore
Zone-2: Indian Institute of Technology Bombay
Zone-3: Indian Institute of Technology Delhi
Zone-4: Indian Institute of Technology Guwahati
Zone-5: Indian Institute of Technology Kanpur
Zone-6: Indian Institute of Technology Kharagpur
Zone-7: Indian Institute of Technology Madras
Zone-8: Indian Institute of Technology Roorkee
The GATE committee, which comprises of representatives from the administering institutes, is the sole authority for regulating the examination and declaring the results.
GATE is conducted through the constitution of eight zones. The zones and the corresponding administrative institutes are:
Zone-1: Indian Institute of Science Bangalore
Zone-2: Indian Institute of Technology Bombay
Zone-3: Indian Institute of Technology Delhi
Zone-4: Indian Institute of Technology Guwahati
Zone-5: Indian Institute of Technology Kanpur
Zone-6: Indian Institute of Technology Kharagpur
Zone-7: Indian Institute of Technology Madras
Zone-8: Indian Institute of Technology Roorkee
Top 10 Reasons – Why should one be a Mechanical Engineer ?
1.You get the opportunity to create something tangible and useful.Ur creations will be used by others.It gives u the greatest joy.
2.Its the broadest branch of engineering…so your career options are open even after u graduate:-
Defence,Civil services,High end R&D,Manufacturing,Design,Energy sector,Management,Entrepreneurship,Masters(ME/MS)
3.Variety to be learnt- u learn how to design and make things ranging from a Safety Pin to a Spacecraft.
4.Easy to imagine and visualize whatever u learn
5.Develop a range of skills – u learn the work of a machine operator (machinist), a smith, a foundryman, a mechanic,a plant manager,a researcher and a policy maker.
6.U work with massive machines (majestic in nature) to tiny precision instruments,micro and nano devices.
u’ll be savviest engineer.
7.Importance of ur work.U form the human resource that is required for the survival of any industry and forms the backbone of modern human life.u r the person who may generate power/energy from natural resources,make equipments and processes to mine minerals,make cars, bikes ,buses, trucks, planes,ships(transportation can be compared to human blood that transports nutrients), make machines that manufacture products ranging from food to surgical instruments to weapons,mange factories and businesses.
8.Get paid handsomely(after gaining a few years experience even if not as a fresher).
9.Not much of girls hanging around(they usually don’t prefer to opt for this course,its thought to be a manly course).U dont have to worry about getting dressed perfectly for class or for girls giggling at u for some silly or not so silly but serious reason.Ur in a man’s world.But there are a few out of the ordinary and brainy girls who do take up this course and luv it.
10.It sounds and feels nice to be called a Mechanical Engineer.
2.Its the broadest branch of engineering…so your career options are open even after u graduate:-
Defence,Civil services,High end R&D,Manufacturing,Design,Energy sector,Management,Entrepreneurship,Masters(ME/MS)
3.Variety to be learnt- u learn how to design and make things ranging from a Safety Pin to a Spacecraft.
4.Easy to imagine and visualize whatever u learn
5.Develop a range of skills – u learn the work of a machine operator (machinist), a smith, a foundryman, a mechanic,a plant manager,a researcher and a policy maker.
6.U work with massive machines (majestic in nature) to tiny precision instruments,micro and nano devices.
u’ll be savviest engineer.
7.Importance of ur work.U form the human resource that is required for the survival of any industry and forms the backbone of modern human life.u r the person who may generate power/energy from natural resources,make equipments and processes to mine minerals,make cars, bikes ,buses, trucks, planes,ships(transportation can be compared to human blood that transports nutrients), make machines that manufacture products ranging from food to surgical instruments to weapons,mange factories and businesses.
8.Get paid handsomely(after gaining a few years experience even if not as a fresher).
9.Not much of girls hanging around(they usually don’t prefer to opt for this course,its thought to be a manly course).U dont have to worry about getting dressed perfectly for class or for girls giggling at u for some silly or not so silly but serious reason.Ur in a man’s world.But there are a few out of the ordinary and brainy girls who do take up this course and luv it.
10.It sounds and feels nice to be called a Mechanical Engineer.
Trolley Crane Design | Trolley For Material Handling | Trolley Mechanism
The lifting crab of a EOT crane is an independent two motion machine and consists of the hoist machinery built on to a frame, which is mounted on runner wheels, and driven by a motor through suitable gearing. The crab is also known as trolley.
Various designs of crabs, arranged with C.I. side frames, mild steel side frames are in use. But now a days, preference is given to the built up side frames on which the machinery is mounted.
The function of the crab is to provide cross travel motion to the hoisting machinery along the length of the main bridge of the crane. The entire hoisting machinery is mounted on the crab which moves on runner wheel over rails fitted on the main bridge of the crane.
The motion of the crab is derived from an electric motor. A speed reduction gear box and a brake are the essential components of a crab gearing. The motion of the motor is transmitted through the reduction gear box via the brake. The HP of motor is calculated by the formula:
HP=W*S*C / 4500
where,
W=total load of the crane including the dead load any pay load in tons;
S=Speed of the longitudinal motion in meter per minute;
C=Tractive effort in Kg per ton.
The reduction gear box is designed to obtain a speed ratio which can reduce the motor RPM to the appropriate RPM of the crab runner wheel to produce the desired speed of the crab. The reduction ratio per stage of the gearbox is fixed at 4 to 5 and is the same for all stages.
Various designs of crabs, arranged with C.I. side frames, mild steel side frames are in use. But now a days, preference is given to the built up side frames on which the machinery is mounted.
The function of the crab is to provide cross travel motion to the hoisting machinery along the length of the main bridge of the crane. The entire hoisting machinery is mounted on the crab which moves on runner wheel over rails fitted on the main bridge of the crane.
The motion of the crab is derived from an electric motor. A speed reduction gear box and a brake are the essential components of a crab gearing. The motion of the motor is transmitted through the reduction gear box via the brake. The HP of motor is calculated by the formula:
HP=W*S*C / 4500
where,
W=total load of the crane including the dead load any pay load in tons;
S=Speed of the longitudinal motion in meter per minute;
C=Tractive effort in Kg per ton.
The reduction gear box is designed to obtain a speed ratio which can reduce the motor RPM to the appropriate RPM of the crab runner wheel to produce the desired speed of the crab. The reduction ratio per stage of the gearbox is fixed at 4 to 5 and is the same for all stages.
Electric Overhead Travelling Crane | EOT Crane | EOT Crane Parts
The most adaptable and the most widely used type of power driven crane for indoor service is undoubtedly the three motion EOT crane. It serves a larger area of floor space within its own travelling restrictions than any other permanent type hoisting arrangement.
As the name implies, this type of crane is provided with movement above the floor level. Hence it occupies no floor space and this can never interface with any movement of the work being carried out at the floor of the building.
The three motions of such crane are the hoisting motion and the cross travel motion. Each of the motions is provided by electric motors.
The above characteristics have made this type of crane suitable for medium and heavy workshop and warehouses. No engineering erection shop, machine shop, foundry, heavy stores is complete without an EOT crane.
In a steel plant, rolling mill, thermal power plant, hydraulic power plant, nuclear power plant, this type of crane is considered indispensable. In short in all industries, wherein heavy loads are to be handled, EOT crane find its application.
EOT Crane Parts:
A EOT crane consists of two distinct parts
1. Bridge
2. Crab
Bridge:
The Bridge consists of two main girders fixed at their ends and connected to another structural components called the end carriages. In the two end carriages are mounted the main runners or wheels (four or more) which provide the longitudinal motion to the main bridge along the length of the workshop. The motion of the bridge is derived from an electric motor which is geared to a shaft running across the full span of the bridge and further geared to a wheel at each end. In some design separate motors may be fitted at each corner of the main bridge. The wheels run on two heavy rails fixed above the floor level along the length of the shop on two girders, called gantry girder.
Crab:
The Crab consists of the hoisting machinery mounted on a frame, which is in turn mounted on at least four wheels and fitted with suitable machinery for traversing the crab to and fro across the main girders of the crane bridge. Needless to mention that the crab wheels run on two rail sections fixed on the top flange of the main bridge. Thus the load hook has three separate motions, these being the hoisting, cross traverse of the crab, and longitudinal travel of the whole crane. Each motion is controlled independently of the other motions by separate controllers situated in a control cage or in a suitable position for controlling from the floor by pendent chains.
The essential parts are:
1. Bridge– 2 No’s
2. End carriage– 2 No’s
3. Wheel of the bridge– At least 4 No’s
4. Crab (without auxiliary hoist)– 1 No’s
5. Hoisting machinery set– 1 No’s
6. Wheels of crab– At least 4 No’s
7. Bottom Block (without auxiliary hoist)– 1 No’s
8. Lifting hook– 1 No’s
9. Rail on the gantry girder for crane movement– 2 No’s
10. Rail on the bridge for crab movement– 2 No’s
11. Operators cabin– 1 No’s
Tandem Wipers | Windshield Wiper Blades | Electronic Wiper Control
Windshield Wipers:
Conventional wiper drives have only one direction of rotation, and the direction of wiping is changed mechanically. The new electronically controlled motor reverses its direction of rotation at the turning point of the wiper – therefore, the mechanical components require less space.
The electronic controller ensures a maximum visibility area at all times, irrespective of wiping speed, coefficient of friction or wind force. Through exact adherence to the wiping angle, it is possible to reduce the tolerance distance to the edge of the windscreen to a minimum and thus to enlarge the swept area. The controller can detect obstacles such as packed snow at the reversing points and automatically reduces the swept area to prevent the system from blocking. The speed of the motor is reduced before reversal to ensure quiet running.
The electronic speed controller is also very practical in conjunction with a rain sensor: depending on the quantity of water on the windshield, the drive unit can be operated at a continuously variable wiping speed.
The electronically controlled wiper motor also allows the use of two-motor wiper systems. Each wiper arm is moved by its own drive unit, and the electronic controller is responsible for the coordination of the movements.
Advantages:
-This system requires no connecting rods
-Reduced space requirements and
-Lower weight.
Features & Benefits:
An extended parking position is available as an additional function: this means that when the wipers are switched off, the wiper arms are parked under the trailing edge of the bonnet. This improves the aerodynamics of the vehicle. Driving noise is reduced and the driver’s field of vision is enlarged. At the same time, the risk of injury is reduced in the event of accidents with pedestrians and two-wheeled traffic.
Conventional wiper drives have only one direction of rotation, and the direction of wiping is changed mechanically. The new electronically controlled motor reverses its direction of rotation at the turning point of the wiper – therefore, the mechanical components require less space.
The electronic controller ensures a maximum visibility area at all times, irrespective of wiping speed, coefficient of friction or wind force. Through exact adherence to the wiping angle, it is possible to reduce the tolerance distance to the edge of the windscreen to a minimum and thus to enlarge the swept area. The controller can detect obstacles such as packed snow at the reversing points and automatically reduces the swept area to prevent the system from blocking. The speed of the motor is reduced before reversal to ensure quiet running.
The electronic speed controller is also very practical in conjunction with a rain sensor: depending on the quantity of water on the windshield, the drive unit can be operated at a continuously variable wiping speed.
The electronically controlled wiper motor also allows the use of two-motor wiper systems. Each wiper arm is moved by its own drive unit, and the electronic controller is responsible for the coordination of the movements.
Advantages:
-This system requires no connecting rods
-Reduced space requirements and
-Lower weight.
Features & Benefits:
An extended parking position is available as an additional function: this means that when the wipers are switched off, the wiper arms are parked under the trailing edge of the bonnet. This improves the aerodynamics of the vehicle. Driving noise is reduced and the driver’s field of vision is enlarged. At the same time, the risk of injury is reduced in the event of accidents with pedestrians and two-wheeled traffic.
Wednesday 23 January 2013
Underwater Tidal Power | Second Generation Tidal Power Plants | Generating Electricity From Ocean Waves
What is Tidal Energy?
Tidal energy is the power of electricity generation achieved by utilization of the variations in sea level caused primarily by the gravitational effects of the moon, combined with the rotation of the Earth by capturing the energy contained in moving water mass due to tides.
Two types of tidal energy can be extracted:
1. Kinetic Energy: currents between ebbing and surging tides.
2. Potential energy: Difference in height between high and low tides.
In order to be practical for energy production, the height differences needs to be at least 5 meters. Only bays and inlets amplify the height of the tide.
Wave facts:
Waves are caused by a number of forces i.e. wind, gravitational pull from the sun and moon, changes in atmospheric pressure, earthquakes etc. Waves created by wind are the most common waves. Unequal heating of the earth’s surface generates wind and wind blowing over water generates waves.
Types of Tidal Plants
1 Tidal Fences: Turnstiles built between small islands or between mainland and islands. The turnstiles spin due to tidal currents to generate energy.
2 Barrage Tidal Plants: Barrage tidal plants are the most common type of tidal plant. Using a dam to trap water in a basin, and when reaches appropriate height due to high tide, release water to flow through turbines that turn an electric generator.
3 Tidal Turbines: Look like wind turbines, often arrayed in rows but are underwater. Tidal currents spin turbines to create energy.
First generation Tidal Power Plants:
-Tidal Fences
-Barriage style Tidal Power Plants
Second generation Tidal Power Plants:
-Tidal Underwater Wind turbines
-Vertical Axis
-Horizontal Axis
-THAWT Device
Note:
One site has potential to equal the generating power of three nuclear power plants.
Disadvantages of Second generation Tidal Power Plants:
Presently costly
1. Expensive to build and maintain
2. A 1085 MW facility could cost as much as 1.2 billion dollars to construct and run.
Energy from the Moon:
The diagram shows how the gravitational attraction of the moon and sun affect the tides on Earth. The magnitude of this attraction depends on the mass of the object and its distance away. The moon has the greater effect on earth despite having less mass than the sun because it is so much closer. The gravitational force of the moon causes the oceans to bulge along an axis pointing directly at the moon. The rotation of the earth causes the rise and fall of the tides.
When the sun and moon are in line their gravitational attraction on the earth combine and cause a “spring” tide.
When they are as positioned in the first diagram above, 90° from each other, their gravitational attraction each pulls water in different directions, causing a “neap” tide.
The rotational period of the moon is around 4 weeks, while one rotation of the earth takes 24 hours; this results in a tidal cycle of around 12.5 hours. This tidal behaviour is easily predictable and this means that if harnessed, tidal energy could generate power for defined periods of time. These periods of generation could be used to offset generation from other forms such as fossil or nuclear which have environmental consequences. Although this means that supply will never match demand, offsetting harmful forms of generation is an important starting point for renewable energy.
Generating Electricity from the Tide:
Turbines can make electricity when the water turns their blades. The simplest electricity generation system using tides is known as an ebb generating system. It uses a dam, known as a barrage, across an estuary. Sluice gates on the barrage are opened to allow the tide to flow into the estuary on the incoming high tides. They are closed to prevent the water flowing back on the outgoing tide (known as the ebb tide) except through the turbine system.
Two way generation systems, which generate electricity on both the incoming and outgoing tides, are also possible.
Impression of Tidal Turbine Farm:
This form of generation has many advantages over its other tidal energy rivals. The turbines are submerged in the water and are therefore out of sight. They don’t pose a problem for navigation and shipping and require the use of much less material in construction. They are also less harmful to the environment. They function best in areas where the water velocity is 2 – 2.5 m/s. Above this level the turbine experiences heavy structural loads and below this not enough generation takes place.
Types of structures :
-Monopile,
-Lattice/gantries,
-Tripod,
-Moored
will all have individual responses to loadings Seabed mountings need to be able to withstand applied vertical/horizontal forces and moments.
Tidal energy is the power of electricity generation achieved by utilization of the variations in sea level caused primarily by the gravitational effects of the moon, combined with the rotation of the Earth by capturing the energy contained in moving water mass due to tides.
Two types of tidal energy can be extracted:
1. Kinetic Energy: currents between ebbing and surging tides.
2. Potential energy: Difference in height between high and low tides.
In order to be practical for energy production, the height differences needs to be at least 5 meters. Only bays and inlets amplify the height of the tide.
Wave facts:
Waves are caused by a number of forces i.e. wind, gravitational pull from the sun and moon, changes in atmospheric pressure, earthquakes etc. Waves created by wind are the most common waves. Unequal heating of the earth’s surface generates wind and wind blowing over water generates waves.
Types of Tidal Plants
1 Tidal Fences: Turnstiles built between small islands or between mainland and islands. The turnstiles spin due to tidal currents to generate energy.
2 Barrage Tidal Plants: Barrage tidal plants are the most common type of tidal plant. Using a dam to trap water in a basin, and when reaches appropriate height due to high tide, release water to flow through turbines that turn an electric generator.
3 Tidal Turbines: Look like wind turbines, often arrayed in rows but are underwater. Tidal currents spin turbines to create energy.
First generation Tidal Power Plants:
-Tidal Fences
-Barriage style Tidal Power Plants
Second generation Tidal Power Plants:
-Tidal Underwater Wind turbines
-Vertical Axis
-Horizontal Axis
-THAWT Device
Note:
One site has potential to equal the generating power of three nuclear power plants.
Disadvantages of Second generation Tidal Power Plants:
Presently costly
1. Expensive to build and maintain
2. A 1085 MW facility could cost as much as 1.2 billion dollars to construct and run.
Energy from the Moon:
The diagram shows how the gravitational attraction of the moon and sun affect the tides on Earth. The magnitude of this attraction depends on the mass of the object and its distance away. The moon has the greater effect on earth despite having less mass than the sun because it is so much closer. The gravitational force of the moon causes the oceans to bulge along an axis pointing directly at the moon. The rotation of the earth causes the rise and fall of the tides.
When the sun and moon are in line their gravitational attraction on the earth combine and cause a “spring” tide.
When they are as positioned in the first diagram above, 90° from each other, their gravitational attraction each pulls water in different directions, causing a “neap” tide.
The rotational period of the moon is around 4 weeks, while one rotation of the earth takes 24 hours; this results in a tidal cycle of around 12.5 hours. This tidal behaviour is easily predictable and this means that if harnessed, tidal energy could generate power for defined periods of time. These periods of generation could be used to offset generation from other forms such as fossil or nuclear which have environmental consequences. Although this means that supply will never match demand, offsetting harmful forms of generation is an important starting point for renewable energy.
Generating Electricity from the Tide:
Turbines can make electricity when the water turns their blades. The simplest electricity generation system using tides is known as an ebb generating system. It uses a dam, known as a barrage, across an estuary. Sluice gates on the barrage are opened to allow the tide to flow into the estuary on the incoming high tides. They are closed to prevent the water flowing back on the outgoing tide (known as the ebb tide) except through the turbine system.
Two way generation systems, which generate electricity on both the incoming and outgoing tides, are also possible.
Impression of Tidal Turbine Farm:
This form of generation has many advantages over its other tidal energy rivals. The turbines are submerged in the water and are therefore out of sight. They don’t pose a problem for navigation and shipping and require the use of much less material in construction. They are also less harmful to the environment. They function best in areas where the water velocity is 2 – 2.5 m/s. Above this level the turbine experiences heavy structural loads and below this not enough generation takes place.
Types of structures :
-Monopile,
-Lattice/gantries,
-Tripod,
-Moored
will all have individual responses to loadings Seabed mountings need to be able to withstand applied vertical/horizontal forces and moments.
Transverse Horizontal Axis Water Turbine | THAWT | Modern Tidal Energy | Most Efficient Wind Turbine
Tidal Energy:
Tidal power is one such developing technology, which harnesses the kinetic and gravitational potential energy in tidal streams. When compared to other renewable sources, tidal streams are a relatively reliable source of energy, as tidal movements can be accurately predicted in terms of direction, timing and magnitude. The rapid development of devices for tidal energy exploitation is being encouraged by government initiatives and by private investment.
The horizontal axis, axial-flow turbine is the most common design of a tidal stream turbine. A number of variants of this type of device, which incorporate features such as flow-guiding shrouds or specific mounting techniques, have been proposed by different developers, but the underlying hydrodynamics remain similar for these devices. However, a drawback with such designs is that their size cannot be increased significantly, because the limited depth of flow at most sites restricts their diameter. Tidal stream energy is likely to be more expensive than either other renewable resources or combined cycle gas turbines, until at least hundreds of megawatts capacity is installed.
How Does a Free Flow Underwater Turbine Work?
Very simply, it works like a wind turbine, but the blades are moved by a water current instead of by the wind.
Transverse Horizontal Axis Water Turbine (THAWT):
The Transverse Horizontal Axis Water Turbine (THAWT) has been proposed as a tidal device which can be easily scaled and requires fewer foundations, bearings seals and generators than a more conventional axial-flow device. The THAWT device is a horizontally deployed variant of the Darrieus cross-flow turbine, in which the blades can be oriented into a truss configuration to produce long, stiff multi-bay rotors.
A fluid particle passing through a Darrieus cross-flow turbine encounters two sets of blades. One on the front side of the turbine as the fluid enters, and again on the rear side as it leaves.
This increased stiffness and strength allows longer units to be constructed, and reduces the overall costs of foundations, bearings, seals and generators. A full scale device might have a diameter of 10 – 20 m and would operate in a flow depth of 20 – 50 m.
The THAWT device employs a truss design of blades, which is intended to increase the rigidity of the structure, so that it can be stretched across a channel without significant increases in blade stresses.
The Thawt device is mechanically far less complicated than anything available today, meaning it would cost less to build and maintain. "The manufacturing costs are about 60% lower, the maintenance costs are about 40% lower”.
The size of thawt is not limited by the depth of water in which it is situated, and the need to intersect the largest possible area of current has been incorporated into the design. Power generation of up to 100mw could be achieved by an array of only 10 thawt devices.
For comparison, if thawt devices were extended across the same area of current as axial flow devices, thawt would require:
-Less generators,
-Less primary seals, and
-Less foundations
and consequently thawt would incur:
-Lower capital costs
-Lower maintenance costs, and
-Lower operational costs
Tidal power is one such developing technology, which harnesses the kinetic and gravitational potential energy in tidal streams. When compared to other renewable sources, tidal streams are a relatively reliable source of energy, as tidal movements can be accurately predicted in terms of direction, timing and magnitude. The rapid development of devices for tidal energy exploitation is being encouraged by government initiatives and by private investment.
The horizontal axis, axial-flow turbine is the most common design of a tidal stream turbine. A number of variants of this type of device, which incorporate features such as flow-guiding shrouds or specific mounting techniques, have been proposed by different developers, but the underlying hydrodynamics remain similar for these devices. However, a drawback with such designs is that their size cannot be increased significantly, because the limited depth of flow at most sites restricts their diameter. Tidal stream energy is likely to be more expensive than either other renewable resources or combined cycle gas turbines, until at least hundreds of megawatts capacity is installed.
How Does a Free Flow Underwater Turbine Work?
Very simply, it works like a wind turbine, but the blades are moved by a water current instead of by the wind.
Transverse Horizontal Axis Water Turbine (THAWT):
The Transverse Horizontal Axis Water Turbine (THAWT) has been proposed as a tidal device which can be easily scaled and requires fewer foundations, bearings seals and generators than a more conventional axial-flow device. The THAWT device is a horizontally deployed variant of the Darrieus cross-flow turbine, in which the blades can be oriented into a truss configuration to produce long, stiff multi-bay rotors.
A fluid particle passing through a Darrieus cross-flow turbine encounters two sets of blades. One on the front side of the turbine as the fluid enters, and again on the rear side as it leaves.
This increased stiffness and strength allows longer units to be constructed, and reduces the overall costs of foundations, bearings, seals and generators. A full scale device might have a diameter of 10 – 20 m and would operate in a flow depth of 20 – 50 m.
The THAWT device employs a truss design of blades, which is intended to increase the rigidity of the structure, so that it can be stretched across a channel without significant increases in blade stresses.
The Thawt device is mechanically far less complicated than anything available today, meaning it would cost less to build and maintain. "The manufacturing costs are about 60% lower, the maintenance costs are about 40% lower”.
The size of thawt is not limited by the depth of water in which it is situated, and the need to intersect the largest possible area of current has been incorporated into the design. Power generation of up to 100mw could be achieved by an array of only 10 thawt devices.
For comparison, if thawt devices were extended across the same area of current as axial flow devices, thawt would require:
-Less generators,
-Less primary seals, and
-Less foundations
and consequently thawt would incur:
-Lower capital costs
-Lower maintenance costs, and
-Lower operational costs
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