Solar Power Satellites(mechanical seminar topic)

The new millennium has introduced increased pressure for finding new renewable energy sources. The exponential increase in population has led to the global crisis such as global warming, environmental pollution and change and rapid decrease of fossil reservoirs. Also the demand of electric power increases at a much higher pace than other energy demands as the world is industrialized and computerized. Under these circumstances, research has been carried out to look into the possibility of building a power station in space to transmit electricity to Earth by way of radio waves-the Solar Power Satellites. Solar Power Satellites(SPS) converts solar energy in to micro waves and sends that microwaves in to a beam to a receiving antenna on the Earth for conversion to ordinary electricity.

SPS is a clean, large-scale, stable electric power source. Solar Power Satellites is known by a variety of other names such as Satellite Power System, Space Power Station, Space Power System, Solar Power Station, Space Solar Power Station etc. One of the key technologies needed to enable the future feasibility of SPS is that of Microwave Wireless Power Transmission.WPT is based on the energy transfer capacity of microwave beam i.e, energy can be transmitted by a well focused microwave beam. Advances in Phased array antennas and rectennas have provided the building blocks for a realizable WPT system.

Increasing global energy demand is likely to continue for many decades. Renewable energy is a compelling approach - both philosophically and in engineering terms. However, many renewable energy sources are limited in their ability to affordably provide the base load power required for global industrial development and prosperity, because of inherent land and water requirements. The burning of fossil fuels resulted in an abrupt decrease in their .it also led to the green house effect and many other environmental problems. Nuclear power seems to be an answer for global warming, but concerns about terrorist attacks on Earth bound nuclear power plants have intensified environmentalist opposition to nuclear power.

Moreover, switching on to the natural fission reactor, the sun, yields energy with no waste products. Earth based solar panels receives only a part of the solar energy. It will be affected by the day & night effect and other factors such as clouds. So it is desirable to place the solar panel in the space itself, where, the solar energy is collected and converted in to electricity which is then converted to a highly directed microwave beam for transmission. This microwave beam, which can be directed to any desired location on Earth surface, can be collected and then converted back to electricity. This concept is more advantageous than conventional methods. Also the microwave energy, chosen for transmission, can pass unimpeded through clouds and precipitations.

SPS
The concept of a large SPS that would be placed in geostationary orbit was invented by Peter Glaser in 1968. The SPS concept was examined extensively during the late 1970s by the U.S Department of Energy (DOE) and the National Aeronautics and Space Administration (NASA). The DOE-NASA put forward the SPS Reference System Concept in 1979. The central feature of this concept was the creation of a large scale power infrastructure in space, consisting of about 60 SPS, delivering a total of about 300GW.But, as a result of the huge price tag, lack of evolutionary concept and the subsiding energy crisis in 1980-1981, all U.S SPS efforts were terminated with a view to re-asses the concept after about ten years. During this time international interest in SPS emerged which led to WPT experiments in Japan.

transmit mixer and concrete pump

In a Ready Mix Concrete (R M C) batching plant, there are two units.
1. Mixing unit
2. Delivery unit

The transit mixer and concrete pumps are the delivery units of a RMC plant. The transit mixer used to deliver the RMC of same workability and quality at work site and the concrete pump is used to deliver the RMC at the desired place as per requirements. Before discussing about Transit mixer and concrete pump, must discuss about the significance of RMC

mechanism

The mechanisms of deterioration of concrete due to various physical, chemical, biological and environmental pollutants are widely researched. In search of possible reasons of non performance of concrete on the face of such voluminous researched. It is necessary to recognize the interactive nature of various factors such as there is interaction between various aggressiveness temperature and humidity as well as the nature of resultant concrete, e.g. PH value, chloride bounding, electrical resistivity etc. The distress to concrete structures is quiet often due to non adherence to the requirements of specifications. The areas a of non compliance not only related to the appropriateness of ingredients of concrete , adequacy of mix properties, but also to workmanship-notably placing, compaction and curing of concrete. Specifications are often difficult to check on site. That results in difficulties is ensuring compliances of specifications and certainty regarding quality achieved. RMC can play a significant role in ensuring quality and durability of concrete that goes in to the structures.

RMC is a revolutionary product, which metamorphosed the entire construction industry. It is a factory made, quality product produced by skilled persons with the help of advanced state-of-the art of technology.

The advanced state-of-the art of technology means play of machineries for the fruitful production of RMC. The RMC plant mixer should always computerized. Here only deals about the transit mixer and concrete pump - the delivery units of RMC-.

Transit mixer that ensure timely delivery of concrete of same workability and quality at the work site.

The concrete pump is used to deliver the concrete at the desired place as per requirements.

The name itself gives a picture of the machine. Basically it is a vehicle with a rotating mixing drum. The drum is rotating during the traveling of the vehicle to the work site. This rotation of the mixer drum ensures the concrete of same workability and quality. Transit mixer used only in RMC plants and which timely deliver the concrete to the work site.

Parts of transit mixer.

1. Auxiliary frame.
2. Discharge support.
3. Detachable feed hopper.
4. Crank chute support.
5. Swiveling discharge chute.
6. Additional extension chute.
7. Bearing pedestals.
8. Drum bearing.
9. Water tank support.
10. Water tank.
11. Mixing drum.
12. Rollers.
13. Water pump.
14. Diesel engine.
15. Suction filter
16. Control cabinet.

MICRO-ELECTROMECHANICAL SYSTEMS

SUMMARY
MEMS are already used as accelerometers in automobile air-bags. They've replaced a less reliable device at lower cost and show promise of being able to inflate a bag not only on the basis of sensed deceleration but also on the basis of the size of the person they are protecting. Basically, a MEMS device contains micro-circuitry on a tiny silicon chip into which some mechanical device such as a mirror or a sensor has been manufactured. Potentially, such chips can be built in large quantities at low cost, making them cost-effective for many uses.

Introduction
Among the presently available uses of MEMS or those under study are:

Global position system sensors that can be included with courier parcels for constant tracking and that can also sense parcel treatment en route .
Sensors built into the fabric of an airplane wing so that it can sense and react to air flow by changing the wing surface resistance; effectively creating a myriad of tiny wing flaps .
Optical switching devices that can switch light signals over different paths at 20-nanosecond switching speeds
Sensor-driven heating and cooling systems that dramatically improve energy savings .
Building supports with imbedded sensors that can alter the flexibility properties of a material based on atmospheric stress sensing .

SMART BOMBS(MECHANICAL SEMINAR TOPIC)

Introduction

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
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.

Computer Aided Process Planning (mechanical seminar topics)

SUMMARY/INTRODUCTION

Technological advances are reshaping the face of manufacturing, creating paperless manufacturing environments in which computer automated process planning (CAPP) will play a preeminent role. The two reasons for this effect are: Costs are declining, which encourages partnerships between CAD and CAPP developers and access to manufacturing data is becoming easier to accomplish in multivendor environments. This is primarily due to increasing use of LANs; IGES and the like are facilitating transfer of data from one point to another on the network; and relational databases (RDBs) and associated structured query language (SQL) allow distributed data processing and data access.
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With the introduction of computers in design and manufacturing, the process planning part needed to be automated. The shop trained people who were familiar with the details of machining and other processes were gradually retiring and these people would be unavailable in the future to do process planning. An alternative way of accomplishing this function was needed and Computer Aided Process Planning (CAPP) was the alternative. Computer aided process planning was usually considered to be a part of computer aided manufacturing. However computer aided manufacturing was a stand alone system. Infact a synergy results when CAM is combined with CAD to create a CAD/CAM. In such a system CAPP becomes the direct connection between design and manufacturing.

Moreover, the reliable knowledge based computer-aided process planning application MetCAPP software looks for the least costly plan capable of producing the design and continuously generates and evaluates the plans until it is evident that non of the remaining plans will be any better than the best one seen so far. The goal is to find a useful reliable solution to a real manufacturing problem in a safer environment. If alternate plans exist, rating including safer conditions is used to select the best plans

WHAT IS CAD?

A product must be defined before it can be manufactured. Computer Aided Design involves any type of design activity that makes use of the computer to develop, analyze or modify an engineering design. There are a number of fundamental reasons for implementing a computer aided design system.
a. Increase the productivity of the designer: This is accomplished by helping the designer to visualize the product and its component subassemblies and parts; and by reducing the time required in synthesizing, analyzing, and documenting the design. This productivity improvement translates not only into lower design cost but also into shorter project completion times.
b. To improve the quality of the design: A CAD system permits a more thorough engineering analysis and a larger number of design alternatives can be investigated. Design errors are also reduced through the greater accuracy provided by the system. These factors lead to a better design.
c. To improve communications: Use of a CAD system provides better engineering drawings, more standardization in the drawings, better documentation of the design, fewer drawing error, and greater legibility.
d. To create a database for manufacturing: In the process of creating a the documentation for the product design (geometries and dimensions of the product and its components, material specification for components, bill of materials etc), much of the required data base to manufacture the product is also created.

Design usually involves both creative and repetitive tasks. The repetitive tasks within design are very appropriate for computerization.

Mine Detection Using Radar Bullets(Mechanical seminar topic)

SUMMARY

Now a day in places like Afghanistan and Iraq we know that land mines are causing serious threat to the lives of civilians. The mines that are implanted during the wartime may remain undetected for several decades and may suddenly be activated after that. Also during wartime mines implanted by our enemy countries are to be detected and diffused properly in order to save the lives of our soldiers. So we should say that detecting landmines is important for every country today.

AFFECTION

The countries known to have severe landmine problems are Afghanistan, Bosnia, Cambodia, Ethiopia, Vietnam, Iraq, Kuwait, Laos, Egypt, Eritrea, Chevalier, China. Unfortunately India, Pakistan, Srilanka, Myanmar are in the list of less mine affected countries besides other 100 countries.

LAND MINE>>>>>>>

The purpose of a landmine is to disable, immobilize or kill. It is an explosive device activated either by a person or vehicle or by command detonated by electric wire or radio signals. Most land mines are laid on just below the surface of ground and are activated by pressure or trip-wire. Usually most of the land mines will contain many metallic parts, which can be made use of in their detection.

Anti-personal mines claims 70 new victims every day. This weapon is particularly cruel on children whose bodies being smaller and closer to the blast are more likely to sustain serious injury. The severe disabilities and psychological traumas that follow the blast- means these children will have to be looked after for many years.

A child injured at the age of 10 will need about 25 critical limbs during there life time. This cost in 3000 Dollars a huge sum to pay in countries where people earn as little as 10 dollar a month. . Between 1979 of 1996 the red crores fitted over 70,000 amputees with critical limbs and the land mine problem in still growing. There for considering these factors the discovery of radar bullet is really a big boost to our world as we launches to 21st century.

RADAR BULLET

The radar bullet is a special type of bullet. The main use of radar bullet is to find landmines without setting foot on the ground. This consists of firing a special bullet in to the ground from a helicopter, which could pin point buried land mines.

The bullet units a radar pulse as it grounds to a halt. This pulse strikes the mine and its image gets available on the computer in the helicopter, offering a safe and efficient way of finding land mines

Apache Helicopter(mechanical seminar topics)

summary
The Apache Helicopter is a revolutionary development in the history of war. It is essentially a flying tank- a helicopter designed to survive heavy attack and inflict massive damage. It can zero in on specific targets, day or night, even in terrible weather. As you might expect, it is a terrifying machine to ground forces.

In this topic, we look at the Apache's amazing flight systems, engines, weapon systems, sensor systems and armour systems. Individually these components are remarkable pieces of technology. Combined together they make up an unbelievable fighting machine - the most lethal helicopter ever created.

HISTORY

The first series of Apaches, developed by Hughes Helicopters in the 1970s, went into active service in 1985. The U.S military is gradually replacing this original design, known as the AH-64A Apache, with the more advanced AH-64D Apache Longbow. In 1984, Mc Donnell Douglas purchased Hughes Helicopters, and in 1997, Boeing manufactures Apache helicopters, and the UK-based GKN Westland helicopters manufacturers the English versions of the Apache, the WAH-64.

DRAG: Drag is an aerodynamic force that resists the motion of an object moving through a fluid. The amount of drag depends on a few factors, such as the size of the object, the speed of the car and the density of the air.

THRUST: Thrust is an aerodynamic force that must be created by an airplane in order to overcome the drag. Airplanes create thrust using propellers, jet engines or rockets.

WEIGHT: This is the force acting downwards or the gravitational force.

LIFT: Lift is the aerodynamic force that holds an airplane in the air, and is probably the important of the four aerodynamic forces. Lift is created by the wings of the airplane.

Lift is a force on a wing immersed in a moving fluid, and it acts perpendicular to the flow of the fluid but drag is the same thing, but acts parallel to the direction of the fluid flow.

1. Air approaching the top surface of the wing is compressed into the air above it as it moves upward. Then, as the top surface curves downward and away from the air stream, a low pressure area is developed and the air above is pulled downward toward the back of the wing.
2. Air approaching the bottom surface of the wing is slowed, compressed and redirected in a downward path. As the air nears the rear of the wing, its sped and pressure gradually match that of the air coming over the top. The overall pressure effects encountered on the bottom of the wing are generally less pronounced than those on the top of the wing.

3.1 FOR STRAIGHT AND LEVEL FLIGHT

The following relationships must be true:
THRUST = DRAG
WEIGHT = LIFT

If for any reason, the amount of drag becomes larger then the amount of thrust, the plane will slow down. If the thrust is increased so that it is greater than drag, the plane will speed up.

If the amount of lift drops below the weight of the airplane, the plane will descend. By increasing the lift, the pilot can make the airplane climb