Mechanical Engineering Seminar Abstract And Report 3
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15-02-2009, 02:27 PM
Automobile Air Conditioning
Due to varying conditions of heating, ventilating, cooling and dehumidification in atmosphere at various places, the air conditioning of automobiles is very essential. To maintain human comfort and improve internal atmosphere in an enclosed space, proper control of freshness temperature, humidity and cleanliness of air required. In an automobile the air conditioning system involvs two main processes of heating and cooling. In the heating system, warm water from the engine cooling system is used. The heat required to warm the automobile is generally provided by circulating warm water through heating coil. For producing cooling effect the evaporator coil operated by refrigeration system is placed inside the chamber of automobile. The components used for producing cooling effect, its working are discussed here.
Non Conventional Energy System
Non Conventional Energy System
Throughout the history of human kind, energy has been an important factor is development. The availability and exploitation of new energy sources has made possible major economic and social changes. Modern societies requiring a large amount of energy used in agricultural, industrial and transport uses. Energy sources can be classified as commercial energy sources and non-commercial energy sources. Commercial sources includes fossil fuels (coal, oil, Naturalgas) while non-commercial energy sources includes wood, animal waste agricultural waste etc..
In industrialized countries like the USA, Commercial energy sources are used. In industry less country like India commercial energy sources and non-commercial energy sources are equal. Commercial energy sources has led to the better quality of life, but it has also created many problems. The most series problem is the harmful effect on the environment. To avoid this problem renewable energy sources are used. The renewable energy sources include solar energy, wind, ocean thermal etc. These energy sources made good economic and social growth
The widespread increase in the quantity of production requiring a multiplicity of operation such as, milling, facing, boring, grilling has led to the development of a method of manufacture known as transfer machine. A transfer machine consists of several machining heads, or units fastened together by conveying units, the whole constituting one automatic installation. In short, a transfer device is a combination of arranged and integrated with interlocked controls and a transferring device to form an automatic machine. The term transfer refers to the transfer of the job from machining station to the next as it proceeds through the machining processes involved. Components are loaded at one end and completed workpieces leave the transfer line at the other end. Application of transfer machining leads to increase in productivity, and reduces the number of machine tools and floor space by 30 to 50 percent. Transfer machining also leads to better quality and reduced manufacturing cost
Air Suspension system
Air Suspension system
The frame as well as body of a vehicle is attached to the rear axle and the front axle by springs. These springs damp the road shock transmitted to the body structure by the wheels, when they travel over the road. In this way the springs are the protecting units supported directly by the frame of the vehicle. Therefore all the parts which perform the function of protection are collectively called a suspension system. These springs are generally of the laminated leaf type, coil type, torsion bar type, hydraulic springs, Plastic springs, Air springs etc.
1. To prevent the road shocks from being transmitted to the vehicle frame. 2. To preserve the stability of the vehicle in pitching or rolling while in motion. 3. To safe guard the occupants from road shocks. 4. To provide good road holding while driving, cornering and breaking 5. To maintain proper steering geometry. 6. To provide the requisite height to body structure as well as to bear the torque and braking reactions. 7. To minimize the effects of stresses due to road shocks on the mechanism of the motor vehicle and provide a cushioning effect. 8. To keep the body perfectly in level while travelling over rough uneven ground. ie, the up and down movement of the wheels should be relative to the body
Sensotronic Braking System
Sensotronic Braking System
The most vital factor in the running and control of the modern vehicles is the braking system. The means of slowing down or bringing down to rest a moving vehicle in shortest possible distance is called brakes. Lives and comfort of not only the driver but also those other road users are saved. The brakes provided by the manufacturers should be effective, safe on operation, progressive and consistent in response to the pedal as well as reasonably easy to adjust.
Sensotronic brake system is regarded as an important milestone to enhance driving safety. With the new SBS, drivers can even cope with extremely difficult situations. In this system electric impulses are used to pass the drivers braking commands on to a micro computer which processes various sensor signals simultaneously and depending on the particular during situation, calculates the optimum brake pressure for each wheel. As a result SBS offers even greater active safety than conventional brake systems.
Air Suspension System
Air Suspension System
Welded joints in a welded structure are expected to possess certain service-related capabilities. Welded joints are generally required to carry loading of various types in which the weld is subjected to stress of either a simple or complex character. More over a finished weld is not always as good or as bad as it may appear to be on its surface. It is therefore necessary to find out how satisfactory or sound the weld is. For this purpose certain weld inspection and testing procedures have been discovered and standardized to estimate the expected performance of the welded structures.
The examination and test applied to welded joints range from relatively simple ones such as visual inspection of the surface of the weld which provides some information on the quality of the workmanship and presence or absence of surface defects to the more elaborate procedures carried out for the purpose of obtaining some knowledge of the behavior of the welded joint under operating conditions.
Electro Static Precipitator
Electro Static Precipitator
Energy conversion and equipment are closely related due to industrialisation and increase in population our environment is polluted vigorously. Many of the industries and fossil fuel power plant emit CO2, CO, particulate matter, heat and other poisonous gases to the atmosphere. Resulting many problems like global warming, health hazards, environmental degrading etc. We need clean air, atmosphere and surrounding for good health and better quality of living.
The energy needs are increasing due to industrial advancement higher standard of timing, increasing population etc. There is no way other than increasing the production of usable energy. But we know that every man made energy conversion has contain degrading effect on the environment. The task is to convert energy with out exceeding the limits of pollution. So every one of as has a question how to control the pollution. Various alternatives are being examined and studied about the employment of different pollution control equipment by National Environmental protection agency and environmentalist. One of the instrument which control the quantity of particulate matter is Electro-static precipitator
Air cylinders resemble any other cylinder in steam engine or cylinder in hydraulic circuit. Air cylinders are called actuators or motors. Air Cylinder is a device, which converts pneumatic power in to respired Mechanical power by reducing the pressure of the compressed air to atmospheric pressure. The advantage of air cylinder is that it cannot be over loaded. It simply stalls when the cylinder is over loaded. The essential parts are of Air Cylinder
1. Cylinder tube
3. Piston rod
4. Air inlet
5. Air outlet Classification of Air Cylinder
1. According to motion obtained a. Rotating b. Non rotating
2. According to operating loads a. Light duty b. Medium duty c. Heavy duty
3. According to number of pressure faces of piston a. Single acting b. Double acting
4. According to the piston of arrangement a. Tanden b. Duplex c. Double ended d. air cushion e. Multi position cylinder f. Impact cylinder g. Cable cylinder
5. According to mounting of cylinder a. Centre line mounting b. Rod end flange mounting c. Trunnion mounting d. Hinged mounting e. Horizontal pedestal mounting f. Rabbetted mounting
6. According to construction a. Piston type b. Diaphram type
Free Piston Engine
Free Piston Engine
The Free Piston Engine is a combination of reciprocating engine and rotary turbine. It is called free piston engine because the freedom motion for Mechanical linkage which gives variable stroke according to load.
1. Mechanical simplicity 2. Less power to weight ratio 3. Lower turbine operating tempeatures 4. Multi fuel capability 5. Flexibility and reliability 6. Easy starting and control
1. Poor fuel economic 2. Less stability 3. Poor part load efficiency 4. High combustine rates 5. Reduction gearing
1. Free piston engines are widely used as submarine air compressor units 2. These engines are suitable for power generation in medium power range 3. Free piston engine have been tride in ship propulsion, road and rail traction and even in aircrafts. 4. It is used in mixed gas steam cycle.
Re-entry of Space Vehicle
Re-entry of Space Vehicle
The successful exploration of space requires a system that will reliably transport payload such as personnel and instrumental etc. into space and return them back to earth without subjecting them an uncomfortable or hazardous environment. In other words, the spacecraft and its payloads have to be recovered safely into the earth. We have seen the re-entry capsules and winged space vehicles approach the earth followed by safe landing. However, this could be accomplished only after considerable research in high speed aerodynamics and after many parametric studies to select the optimum design concept.
Re-entry systems were among the first technologies developed in 1960s for military photo-reconnaissance, life science and manned space flights. By 1970s, it led to the development of new refurbish able space shuttles. Today space technology has developed to space planes which intend to go and come back regularly from earth to space stations. USA's HERMS and Japan's HOPE is designed to land at conventional airports. Few significant advances in current proposed re-entry capsules are ballistic designs to reduce development and refurbishable cost, to simplify operations.
For entering into atmospheric and non-atmospheric planet the problem involves is reducing the spacecraft's speed . For an atmospheric planet the problem involves essentially deceleration, aerodynamic heating, control of time & location of landing. For non-atmospheric planets, the problem involves only deceleration and control of time & location of landing.
The vehicle selected to accomplish a re-entry mission incorporates a thick wing , subsonic ( Mach < 1 ) airfoil modified to meet hypersonic (Mach>> 1 ) thermodynamic requirements. The flight mechanics of this vehicle are unique in that rolling manoeuvres are employed during descent such that dynamic loading and aerodynamic heating are held to a minimum.
Therefore re-entry technology requires studies in the following areas:
2. Aerodynamic heating & air loads
3. Vehicle stability
4. Thermal Protection Systems (TPS)
5. Guidance and Landing.
Re-entry mission profile, constraints And vehicle requirements The safe recovery of the spacecraft and its payloads is made possible by the re-entry mission. According to the different constraints the mission profile can be divided into three distinct flight segments:-
1. Deorbit and Descent to sensible atmosphere at an altitude of nearly 120kms.
2. Re-entry and hypersonic glide fight.
3. Transition flight phase, final approach and landing.
The unguided first flight segment (Keplarian trajectory) initiated by a rocket deboost maneuver at a specific orbital point determines the flight condition at re-entry. The second flight segment covers the atmospheric glide at an altitude of 120 km to 30 km during which the re-entry vehicle's high initial kinetic energy is dissipated by atmospheric breaking. The third flight segment does the final approach and landing.
The various forces acting on the re-entry vehicle are:-
1. Gravitational force acting towards the centre of the planet.
2. Gas dynamic force opposite to the direction of motion of the vehicle.
3. Centrifugal and gas dynamic lift force acting normal to the direction of
4. motion of the vehicle.
Sensotronic Brake Control
Sensotronic Brake Control
Sensotronic Brake Control (SBCâ€žÂ¢) works electronically, and thus faster and more precisely, than a conventional hydraulic braking system. As soon as you press the brake pedal and the sensors identify the driving situation in hand, the computer makes an exact calculation of the brake force necessary and distributes it between the wheels as required. This allows SBCâ€žÂ¢ to critically reduce stopping distances. SBCâ€žÂ¢ also helps to optimise safety functions such as ESPÃ‚Â®, ASR, ABS and BAS. With Sensotronic Brake Control, electric impulses are used to pass the driver's braking commands onto a microcomputer which processes various sensor signals simultaneously and, depending on the particular driving situation, calculates the optimum brake pressure for each wheel. As a result, SBC offers even greater active safety than conventional brake systems when braking in a corner or on a slippery surface.
A high-pressure reservoir and electronically controllable valves ensure that maximum brake pressure is available much sooner. Moreover, the system offers innovative additional functions to reduce the driver's workload. These include Traffic Jam Assist, which brakes the vehicle automatically in stop-and-go traffic once the driver takes his or her foot off the accelerator. The Soft-Stop function - another first - allows particularly soft and smooth stopping in town traffic
When drivers hit the brake pedal today, their foot moves a piston rod which is linked to the brake booster and the master brake cylinder. Depending on the pedal force, the master brake cylinder builds up the appropriate amount of pressure in the brake lines which - in a tried and tested interaction of mechanics and hydraulics - then presses the brake pads against the brake discs via the wheel cylinders.
By contrast, in the Mercedes-Benz Sensotronic Brake Control, a large number of mechanical components are simply replaced by electronics. The brake booster will not be needed in future either. Instead sensors gauge the pressure inside the master brake cylinder as well as the speed with which the brake pedal is operated, and pass these data to the SBC computer in the form of electric impulses. To provide the driver with the familiar brake feel, engineers have developed a special simulator which is linked to the tandem master cylinder and which moves the pedal using spring force and hydraulics.
In other words: during braking, the actuation unit is completely disconnected from the rest of the system and serves the sole purpose of recording any given brake command. Only in the event of a major fault or power failure does SBC automatically use the services of the tandem master cylinder and instantly establishes a direct hydraulic link between the brake pedal and the front wheel brakes in order to decelerate the car safely.
The central control unit under the bonnet is the centrepiece of the electrohydraulic brake. This is where the interdisciplinary interaction of mechanics and electronics provides its greatest benefits - the microcomputer, software, sensors, valves and electric pump work together and allow totally novel, highly dynamic brake management:
In addition to the data relating to the brake pedal actuation, the SBC computer also receives the sensor signals from the other electronic assistance systems.
For example, the anti-lock braking system (ABS) provides information about wheel speed, while Electronic Stability Program (ESPÃ‚Â®) makes available the data from its steering angle, turning rate and transverse acceleration sensors. The transmission control unit finally uses the data highway to communicate the current driving range. The result of these highly complex calculations is rapid brake commands which ensure optimum deceleration and driving stability as appropriate to the particular driving scenario. What makes the system even more sophisticated is the fact that SBC calculates the brake force separately for each wheel.
Skid Steer Loader and Multiterrain Loader
Skid Steer Loader and Multiterrain Loader
Skid-steer loaders began catching on in the construction field in the 1980s because they offered contractors a way to automate functions that had previously been performed by manual labor.
Those were small, inexpensive machines that improved labor productivity and reduced work-related injuries. Their small size and maneuverability allows them to operate in tight spaces. Their light weight allows them to be towed behind a full-size pickup truck, and the wide array of work-tools makes them very flexible. They were utility machines, used for odd jobs ranging from work site clean up to small scale digging, lifting, and loading. In most cases, they logged far fewer hours of usage each year than backhoe loaders and wheel loaders, but they were cheap, and so easy to operate that anyone on a job site could deploy them with very little training.
Since then, the category has become wildly popular in all avenues of construction. They are the best-selling type of construction equipment in North America, with annual sales exceeding 50,000 units. They still tend to be low-hour machines, but, thanks to a virtually unlimited variety of attachments, skid-steer loaders can handle a huge array of small-scale jobs, from general earthmoving and material handling to post hole digging and landscaping to pavement milling and demolition.
As the machine has grown in popularity, it has become one of the hottest rental items in North America. Equipment rental houses consume roughly one-third of the new units sold each year, and most stock a wide array of attachments, too. The ready availability of rental attachments - especially high-ticket, specialty items like planers, vibratory rollers, tillers, and snow blowers and pushers - has turned the machines potential for versatility into a cost-effective reality.
As the skid-steer has become more popular in construction, the average size of the machine has grown, too. In the mid-1980s, the most popular operating load class was 900 to 1,350 pounds. By the mid-1990s, the 1,350 to 1,750 pound class was the most popular. Today, the over-1,750-pound classifications are the fastest growing.
Larger machines have dominated new product introductions, too, though our survey of recent new product announcements has turned up a spate of compact and sub-compact introductions, too. The smallest of these are ride-behind models aimed mainly at the consumer rental trade, but they are also used in landscaping and other types of light construction essentially to automate jobs that would otherwise be done by laborers with shovels.
Road contractors and government highway departments should find the new super-duty class of skid-steer loaders especially interesting. These units have retained the skid-steer's traditional simplicity of operation and compact packaging, while also boasting power and weight specifications that let them perform many of the tasks done by backhoe loaders and compact wheel loaders. Nearly all boast high-pressure, high-flow hydraulic systems to run the most sophisticated hydraulic attachments. They also feature substantial break-out force ratings for serious loading and substantial lifting capacities for material handling.
The skid-steer loader represents an interesting alternative for fleets that have low- hour backhoe loaders in inventory. Led by Bobcat, Gehl, Mustang, and other companies that make skid-steers but not backhoe loaders, skid-steer marketers have been pushing the proposition that it is more cost effective to replace a backhoe loader with a skid-steer and a mini-excavator. The rationale: for about the same amount of money, you can get more hours of utilization because you have two machines that can be working simultaneously at different jobs.
In order to respond to rapidly changing environment and market, it is imperative to have such capabilities as flexibility, adaptability, reusability, etc. for the manufacturing system. The fractal manufacturing system is one of the new manufacturing paradigms for this purpose. A basic component of fractal manufacturing system, called a basic fractal unit (BFU), consists of five functional modules such as an observer, an analyzer, an organizer, a resolver, and a reporter. Each module autonomously cooperates and negotiates with others while processing its jobs by using the agent technology. The resulting architecture has a high degree of self-similarity, one of the main characteristics of the fractal. What this actually means in this case is something that when you look at a part of it, it is similar to the whole object.
Some of the fractal specific characteristics are:
Fractal Robot is a science that promises to revolutionize technology in a way that has never been witnessed before. Fractal Robots are objects made from cubic bricks that can be controlled by a computer to change shape and to reconfigure themselves into objects of different shapes. These cubic motorized bricks can be programmed to move and shuffle themselves to change shape to make objects like a house potentially in few seconds. It is exactly like kids playing with Lego bricks and making a toy house or a toy bridge by snapping together Lego bricks, except that here we are using a computer.
This technology has the potential to penetrate every field of human work like construction, medicine, research and others. Fractal robots can enable buildings to build within a day, help perform sensitive medical operations and can assist in laboratory experiments. Also, Fractal Robots have built-in self repair which means they continue to work without human intervention. Also, this technology brings down the manufacturing price down dramatically.
A Fractal Robot resembles itself, i.e. wherever you look at, any part of its body will be similar to the whole object. The robot can be animated around its joints in a uniform manner. Such robots can be straight forward geometric patterns/images that look more like natural structures such as plants. This patented product however has a cubical structure.A fractal cube can be of any size. The smallest expected size is between 1000 and 10,000 atoms wide. These cubes are embedded with computer chips that control their movement.
FRACTAL ROBOT MECHANISM
SIMPLE CONSTRUCTION DETAILS
Considerable effort has been spent in making the robotic cube as simple as possible after the invention had been conceived. The design is such that it has the fewest possible moving parts so that they can be mass produced. Materials requirements have been made as flexible as possible so that they can be built from metals and plastics which are cheaply available in industrial nations but also from ceramics and clays which are environmentally friendlier and more readily available in developing nations.
The cube therefore is hollow and the plates have all the mechanisms. Each of these face plates have electrical contact pads that allow power and data signals to be routed from one robotic cube to another. They also have 45 degree petals that push out of the surface to engage the neighboring face that allows one robotic cube to lock to its neighbors.
The contact pads are arranged symmetrically around four edges to allow for rotational symmetry
Smart bombs are weapons capable of destroying enemy targets with out the need for a launch aircraft to penetrate the envelops of the air defense systems. These essentially comprise a terminal guidance unit that guides them in the last phase to achieve pinpoint accuracy. Increased accuracy means that a single, moderate-size bomb can give a better result than multiple strikes with larger, non-guided bombs.
Smart bombs are desirable both from ethical and tactical standpoints. On ethical grounds, the military desires that each warhead deployed should strike only its indented target so that innocent civilians are not harmed by misfire. From tactical standpoint, it wants weapons with pinpoint accuracy to inflict maximum damage on valid military targets and minimize the number of strikes necessary to achieve mission objectives. Gravity bombs with laser or GPS/INS guidance are smart bombs that have changed the face of modern warfare
Laser-guided bombs have an internal semi-active guidance system that detects laser energy and guides the weapon to the target illuminated by an external laser designator.Laser designators radiate a narrow beam of pulsed energy in the near infrared wavelength spectrum. These are semi active illuminators used to tag the desired spot. These can be aimed such that laser energy precisely designates the chosen spot on the target. Laser designator can be located in the delivery aircraft, another aircraft or on a ground source.
Typical LGB seekers comprise an array of photo diodes to decode the laser pulsed repetition frequency (PRF) and derive target position signals. Laser designators and seekers use a pulse coding system to ensure that a specific seeker and designator combination work in harmony. By setting the same code in both the designator and the seeker will track only the target designated by the chosen designator.
Laser designators provide precision target marking for air support. LGBs with TV or infrared seeker in their nose show the target to the attacking pilot on a screen in the cockpit. The pilot fixes cross hairs on the target and marks it for the weapon to aim at. The target scatters the received laser energy in all the directions. LGB seeker having a limited field of view receives a small part of the scattered energy and decodes it. If the received PRF code matches the preprogrammed code, the pilot fires the bomb. It then horns onto the reflected laser energy to attack the target
Some LGBs require laser target illumination before launch or release and/ or during the terminal portion of flight. The LGB flight path can be divided into three phases: ballistic, transition, and terminal guidance.
During the ballistic phase, the weapon continues on the unguided trajectory established by the flight path of the delivery aircraft at the moment of release. In this phase, the delivery altitude takes on additional importance, since maneuverability of the unguided bomb is related to the weapon velocity during terminal guidance. Therefore, airspeed lost during the ballistic phase equated to a proportional loss of maneuverability. So the closer to the target the release of the bomb, the more the accuracy of the bomb
The transition phase is where initial acquisition of the designating laser takes place. During this phase, the weapon attempts to align its velocity vector with the line of sight vector to the target. Once a lock has been achieved, the guidance system uses the canards to try and keep the bomb within the cone of the reflected laser energy.
The terminal phase is when the reflected laser centers on the seeker causing the bomb to dive to the target. LGBs are excellent performers in dive deliveries initiated from medium altitude. A steep, fast dive attack increases LGB maneuvering potential and flight ability. Medium-altitude attacks generally reduce target acquisition problems and more readily allow for target designation by either ground or airborne designation platforms. Medium-altitude LGB dive delivery tactics are normally used in areas of low to medium threat.
LGBs miss the target if the laser is turned on too early: During certain delivery profiles where the LGB sees laser energy as soon as it is released, it can turn from its delivery profile too soon and miss by failing short of the target. To prevent this, the laser designator must be turned on at the time that will preclude the bomb from turning down toward the target prematurely. Normally, the pilot knows the proper moment for laser 'on'. The specific LGB and the delivery tactics of the attacking aircraft dictate the minimum designation time required to guide the weapon to the intended target.
The four basic requirements for effective use of laser designators with LGBs are:
1. The PRF code of the laser designator and the LGB must be compatible
2. A direction of attack must be determined because the LGB must be able to sense sufficient laser energy reflecting from the target being designated.
3. The laser designator must designate the target at the correct time.
4. The delivery system must release the weapon within the specific weapon's delivery envelope
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