notes on magnetic levitation

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INTRODUCTION Origin This report has been prepared by the third year SRMCEM students as a part ofthe curriculum ‘Presentation and Communication Techniques’ for the year2015-2016 The report is titled ‘MAGLEV TRAINS’ and deals with the evolution and development of Maglev technology and its execution in transportation via trains. Purpose Our report titled ‘MAGLEV TRAINS’ is an informative report which explainsabout Magnetic levitation or Maglev, as a form of transportation thatsuspends, guides and propels vehicles via electromagnetic force. This method can be faster than wheeled mass transit systems potentially reaching velocities comparable to an aircraft or a turboprop. Our report aims at providing knowledge about the various aspects of this new emerging automotive technology called maglev trains. SRMGPC Page 1

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INTRODUCTION OriginThis report has been prepared by the third year SRMCEM students as a part ofthe curriculum Presentation and Communication Techniques for the year2015-2016 The report is titled MAGLEV TRAINS and deals with theevolution and development of Maglev technology and its execution intransportation via trains. PurposeOur report titled MAGLEV TRAINS is an informative report which explainsabout Magnetic levitation or Maglev, as a form of transportation thatsuspends, guides and propels vehicles via electromagnetic force. Thismethod can be faster than wheeled mass transit systems potentially reachingvelocities comparable to an aircraft or a turboprop. Our report aims atproviding knowledge about the various aspects of this new emergingautomotive technology called maglev trains. ScopeThis report specifically looks into the origin, techniques, implementation,features, updates and accidents involved in maglev trains. However, thereport has not dealt with the expenses, recommendation and alternativetechnologies of maglev trains. LimitationsThis report uses the internet as its primary source of information. Due to theconstraint of time, this report could not extract information from other sources.

SUMMARY-:The report titled MAGLEV TRAINS accomplishes a research on thedeveloping discipline of magnetic levitation and its application totransportation through trains. It provides detailed information about theevolution of maglev science, its progression and improvisation till date. Highspeed magnetically levitated ground transportation (maglev) is a new surfacemode of transportation, in which vehicles glide above their guideways,suspended, guided, and propelled by magnetic forces. This report tries toexplain the complexities involved in this technology in a simple manner, so that all the methods implemented in it are understood by thereader at prima facie. This report, tries to compare the conventional modes oftransport with maglev trains in various aspects such as safety, durability,speed, comfort and so on. Thus, providing the advantages and disadvantagesof the trains. Further, this report helps us to learn about the various citiesaround the world, where maglev trains currently run and also provides anoverview of the proposals for such trains, which are being considered as apromising investment globally. Consecutively, it deals with the accidents thathave occurred at places where maglev trains have been implemented and thereasons that triggered them. This data has been included so that suchincidents may be avoided in the future and in order that certain necessarymodifications are made to improve the safety measures of these trains.Capable of travelling at speeds of 250 to 300 miles-per-hour or higher, maglevwould offer an attractive and convenient alternative for travellers betweenlarge urban areas for trips of up to 600 miles. It would also help relievecurrent and projected air and highway congestion by substituting for shorthaul air trips, thus releasing capacity for more efficient long-haul service atcrowded airports, and by diverting a portion of highway trips. Finally, ourreport gives a peek into the future expansions of maglev trains and thusundoubtedly assures its readers that maglev trains are no longer a sciencefiction, and are in fact the future of world transportation.

MAGLEV PRINCIPAL-:A method of supporting and transporting objects or vehicles which is based onthe physical property that the force between two magnetized bodies isinversely proportional to their distance. By using this magnetic force tocounterbalance the gravitational pull, a stable and contactless suspensionbetween a magnet (magnetic body) and a fixed guideway (magnetized body)may be obtained. In magnetic levitation (Maglev), also known as magneticsuspension, this basic principle is used to suspend (or levitate) vehiclesweighing 40 tons or more by generating a controlled magnetic force. Byremoving friction, these vehicles can travel at speeds higher than wheeledtrains, with considerably improved propulsion efficiency (thrust energy/input energy) and reduced noise. In Maglev vehicles, chassis-mounted magnets areeither suspended underneath a ferromagnetic guideway (track) or levitated above an aluminum track.

Figure 1.1 depicts the three primaryfunctions basic to Maglev technology(1) levitation or suspension;(2) propulsion; and(3) guidanceIn most current designs, magnetic forces are used to perform all threefunctions, although a nonmagnetic source of propulsion could be used. Noconsensus exists on an optimumdesign to perform each of the primaryfunctions.In the attraction-type system, a magnet-guideway geometry is used to attracta direct-current electromagnet toward the track. This system, also known asthe electromagnetic suspension (EMS) system, is suitable for low- and highspeed passenger-carrying vehicles and a wide range of magnetic bearings.The electromagnetic suspension system is inherently nonlinear and unstable,requiring an active feedback to maintain an upward lift force equal to theweight of the suspended magnet and its payload (vehicle).In the repulsion-type system, also known as the electrodynamic levitationsystem (EDS or EDL), a superconducting coil operating in persistent-currentmode is moved longitudinally along a conducting surface (an aluminum platefixed on the ground and acting as the guideway) to induce circulating eddycurrents in the aluminum plate. These eddy currents create a magnetic fieldwhich, by Lenzs law, opposes the magnetic field generated by the travellingcoil. This interaction produces a repulsion force on the moving coil. At lowerspeeds, this vertical force is not sufficient to lift the coil (and its payload), sosupporting auxiliary wheels are needed until the net repulsion force is positive.The speed at which the net upward lift force is positive (critical speed) isdependent on the magnetic field in the airgap and payload, and is typicallyaround 80 km/h (50 mi/h). To produce high flux from the traveling coils, hardsuperconductors (type II) with relatively high values of the critical field (themagnetic field strength of the coil at 0 K) are used to yield airgap flux densitiesof over 4 tesla. With this choice, the strong eddy-current induced magneticfield is rejected by the superconducting field, giving a self-stabilizing levitationThe Types of Maglev MethodsRepulsion between like poles of permanent magnets orelectromagnets.Repulsion between a magnet and a metallic conductor induced byrelative motion.Repulsion between a metallic conductor and an AC electromagnet.Repulsion between a magnetic field and a diamagnetic substance.Repulsion between a magnet and a superconductor.Attraction between unlike poles of permanent magnets orelectromagnets.Attraction between the open core of an electromagnetic solenoid and apiece of iron or a magnet. Attraction between a permanent magnet or electromagnet and a pieceof iron. Attraction between an electromagnet and a piece of iron or a magnet,with sensors and active control of the current to the electromagnetused to maintain some distance between them. Repulsion between an electromagnet and a magnet, with sensors andactive control of the current to the electromagnet used to maintainsome distance between them.Each implementation of the magnetic levitation principle for train-type travelinvolves advantages and disadvantages. Time will tell us which principle, andwhose implementation, wins out commercially.Technology Pros Cons

EMS(Electromagneticsuspension)Magnetic fields insideand outside the vehicleare less than EDS;proven, commerciallyavailable technology thatcan attain very highspeeds (500 km/h); nowheels or secondarypropulsion systemneeded.The separation betweenthe vehicle and theguideway must beconstantly monitoredand corrected bycomputer systems toavoid collision due to theunstable nature ofelectromagneticattraction; due to thesystem's inherentinstability and therequired constantcorrections by outsidesystems, vibration issuesmay occur.

EDS(Electrodynamic)Onboard magnets and large margin between rail and train enable highest recorded trainspeeds (581 km/h) and heavy load capacity; has recently demonstrated (December 2005)successful operationsusing high temperaturesuperconductors in its onboard magnets,cooled with inexpensiveLiquid nitrogenStrong magnetic fields onboard the train wouldmake the train Inaccessible topassengers with pacemakers or magnetic data storage media such as hard drives and credit cards, necessitating theuse of magnetic shielding; limitations on guideway inductivity limit the maximum speed of the vehicle; vehicle must be wheeled for travel atlow speeds.

Inductrack System(Permanent MagnetEDS)Failsafe Suspension - nopower required toactivate magnets;Magnetic field islocalized below the car;can generate enoughforce at low speeds(around 5 km/h) tolevitate Maglev train; incase of power failurecars slow down on theirown safely; Halbacharrays of permanentmagnets may provemore cost-effective thanelectromagnetsRequires either wheelsor track segments thatmove for when thevehicle is stopped. Newtechnology that is stillunder development (asof 2008) and as yet hasno commercial versionor full scale systemprototype.

TECHNOLOGY AND WORKINGOF MAGLEV TRAINS Internal working of the Maglev trains DESIGN ISSUESMaglev is similar to other transport technology: we can 306 create a basic design that is almost independent of speed, 307 but the implementation varies considerably according to 308 the application. As always, the devil is in the details, three 309 of which are discussed in this Section.A.VehicleChoice of vehicle weight, shape and length dominate transport system design. In this paper the term vehicle also refers to trains with any number of mechanically coupled cars. There are three key issues that affect the EI of a transport system and are primarily determined by vehicle design. 1) For high-speed travel the dominant energy usage is to overcome aerodynamic drag. For constant speed travel EI is proportional to the drag force per passenger with 3:6 N/pas 3:6 J/pas-m 1 Wh/pas-km. Airplanes do much better than is possible for ground transportation because at an elevation of 12 000 m (39 3700) the pressure, and hence the drag force, is reduced by a factor of four. An airplane traveling 900 km/h (559 mi/h) is comparable in aerodynamic drag to a maglev vehicle traveling 450 km/h, and with a larger diameter body the energy efficiency can be quite good for long trips. 2) For low-speed travel the dominant energy loss is due to the need to supply kinetic energy to change a vehicles speed, and this is typically lost when the vehicle brakes. For high-speed travel the problem still exists because there is typically a need to slow for turns to achieve acceptable lateral gee forces and to stop at stations. Regenerative braking can reduce the net loss by a factor of two or more provided the propulsion is reasonably efficient and there is a way to reuse the energy.SystemElectronically controlled support magnets located on both sides along theentire length of the vehicle pull the vehicle up to the ferromagnetic statorpacks mounted to the underside of the guideway.Guidance magnets located on both sides along theentire length of the vehicle keep the vehicle laterallyon the track. Electronic systems guarantee that theclearance remains constant (nominally 10 mm). Tohover, the Maglev requires less power than its airconditioning equipment. The levitation system issupplied from on-board batteries and thusindependent of the propulsion system. The vehicleis capable of hovering up to one hour withoutexternal energy. While travelling, the on-boardbatteries are recharged by linear generatorsintegrated into the support magnets.

Propulsion SystemThe synchronous longstatorlinear motor of the Maglevmaglev system is used bothfor propulsion and braking. Itis functioning like a rotatingelectric motor whose stator iscut open and stretched alongunder the guideway. Insidethe motor windings,alternating current isgenerating a magnetictraveling field which movesthe vehicle without contact.The support magnets in thevehicle function as theexcitation portion (rotor). Thepropulsion system in the guideway is activated only in the section where the vehicle actually runs. The speed can be continuously regulated by varying the frequency of the alternating current. If the direction of the traveling field is reversed, the motor becomes a generator which brakes the vehicle without any contact. The braking energy can be re-used and fed back into the electrical network. The three-phase winded stator generates an electromagnetic travelling field and moves the train when it is supplied with an alternating current. The electronmagnetic field from the support electromagnets (rotor) pulls it along.The magnetic field direction and speed of the stator and the rotor are synchronized. The Maglev's speed can vary from standstill to full operatingspeed by simply adjusting the frequency of the alternating current. To bring the train to a full stop, the direction of the travelling field is reversed. Even during braking, there isn't any mechanical contact between the stator and the rotor.Instead of consuming energy, the Maglev system acts as a generator, converting the breaking energy into electricity, which can be used elsewhere.

Process of Propulsion and the traveling field Stator Winding for Propulsion

The Maglev Track-:

Maglev trackThe magnetized coil running along the track, called a guideway, repels thelarge magnets on the train's undercarriage, allowing the train to levitatebetween 0.39 and 3.93 inches (1 to 10 cm) above the guideway. Once thetrain is levitated, power is supplied to the coils within the guideway walls tocreate a unique system of magnetic fields that pull and push the train alongthe guideway. The electric current supplied to the coils in the guideway wallsis constantly alternating to change the polarity of the magnetized coils. Thischange in polarity causes the magnetic field in front of the train to pull thevehicle forward, while the magnetic field behind the train adds more forwardthrust.

MATHAMATICAL ANALYSIS OF SHANGHAI BULLET TRAIN Mechanical System ModelThe train consists of five sections, each section consists of a car body and running gears which connects the levitation and guidance magnets. The running gear is also called Magnetic Wheels. Two adjacent Magnetic Wheels are connected to form a so-called levitation bogie. There are four such levitation bogies under a car body. The levitation bogies are designed to enable transmission of vertical forces to support the car body and to transmit lateral forces to guide the train, transmission of longitudinal forces provides for braking and traction forces. Consequently it is a very important component in the vehicle for both safety and comfort.

There are many suspension elements within the levitation bogie, for example, two air springs, anti-roll bars and rubber elements, primary metal-rubber elements which connect the levitation magnets, lateral bump stop metal-rubber elements, metal-rubber elements which connect the braking magnets, etc.. The car body is connected vertically by 16 swing-rods that provide lateral flexibility. There are two rubber stacks at one end of the Modeling and Simulation of Shanghai MAGLEV Train Transrapid with Random Track Irregularitie swing-rods to give flexibility in the axial direction. The longitudinal forces are transmitted by 4 traction rods to the four frames separately. These suspension elements isolate most disturbances from the guiding track, both vertically and laterally.A vehicle model is created considering 5 degrees of freedom for the car body and 4 degrees of freedom for each magnetic levitation frame and 2 degrees of freedom for each magnet pair. There are eight levitation frames, 14 levitation magnets, 12 guidance magnets and 2 eddy current brake modules for both sides. Totally there are 93 degrees of freedom considered in the mechanical model as show in Figure 1 and 2.

With the assumption of a rigid car body, five degrees for the car body are considered including vertical, lateral,yaw, pitch and rotation movements. There are four levitation bogies beneath the car body, each consists of two relatively rigid frames, called levitation frame. Two levitation frames are connected by a longitudinal structure with relative flexibility and light mass. So the levitation bogie can be treated as two rigid parts (levitation frame) connecting via shear stiffness in the vertical and lateral directions together with a rotational angular stiffness.Each levitation frame is considered with four degrees for vertical, lateral, pitch and rotation movements respectively. Each levitation magnet is suspended from two adjacent levitation frames with relative flexibility vertically and longitudinally. Hence each levitation magnets is considered as having two degrees for vertical and pitch movements respectively. The guidance magnets are also similar to levitation magnets, which are connected to the side of adjacent levitation frames with relative lateral flexibility. The guidance magnets are considered as two degree also, i.e. degrees for lateral and yaw movements respectively.Secondary suspensions between car body and levitation frames are provided through a combination of air springs, rubbers stacks, swing-rods and rotation arms etc. as shown in Figure 2. The rotation arms and swingrods are relatively light in weight. Hence it is not necessary to consider their inertial effects. Whole structures can be simplified with three stiffness, i.e. lateral stiffness Kys, roll stiffness Krs and vertical stiffness Kzs. These three parameters are defined as the function of stiffness of air spring, anti-roll stiffness and several geometric dimensions as follows:Where W is the suspended weight of on each frame. Other parameters are shown in Figure 2. Primary suspensions are simple in this case. There is only vertical stiffness to the levitation magnets and lateral stiffness to the guidance magnets. For the practical application, two magnets consist a pair of vertical magnet levitation block with two gap and acceleration sensors for each magnet. The linear quadratic control can be used for minimum control energywith linearized coefficients at the working point [12,13]. The controller can be treated for individual or modal control.Control System ModelingWith the assumption of a single levitated mass as shown in Figure 3, the controller are designed for both levitation and guidance. There m is the levitated mass (including levitation frame and magnet), f is the dynamic magnet force, zT is the track disturbance and zt is the magnet deviation. S0 is the nominal magnet gap, s is the small deviation from the nominal gap, L0 = Le + Ls is the whole inductance, with the effective inductance Le and the constant stray inductance Ls. R is the resistance, I0 is the nominal current and u is the small deviation from the nominal magnet voltage R I0.With the assumption of a single levitated mass as shown in Figure 3, the controller are designed for both levitation and guidance. There m is the levitated mass (including levitation frame and magnet), f is the dynamic magnet force, zT is the track disturbance and zt is the magnet deviation. S0 is the nominal magnet gap, s is the small deviation from the nominal gap, L0 = Le + Ls is the whole inductance, with the effective inductance Le and the constant stray inductance Ls. R is the resistance, I0 is the nominal current and u is the small deviation from the nominal magnet voltage R I0.

The linear equation of the single mass magnetic levitation system can be derived with LAGRANGEFunction as shown in [12,13,14,15]:


Considering the dynamic magnet force f= Pi I - Ps S, then is

Substituting eq.(2) into eq.(3) and taking note of

there is

where T=R/L0= 0 is the time constant. In order to accord with the vehicle coordinate system in Figure 1 and Figure 2 the transformation is made as below:

Selecting magnet deviation zt ,vertical velocity zt and dynamic magnet force f as the state variables, that isthe following state equation is obtained i.e.

To optimize the system the quadratic loss criterion

is used. There Q and R are the weighting matrices with Then the controller feedback matrix K is obtained as

where P can be solved from the matrix RICCATI-equation

Then the optimal feedback control law is

The weightings in eq.(7) used for the control system design for minimum control energy are

The above single mass control model can be applied to each magnet of the simulated MAGLEV vehicle with the optimized parameters for individual and modal control strategies alternatively as shown in Figure 4.The equation and the design method of guidance control system are similar.

SIMULATION DIAGRAM OF BULLET TRAINThis diagram shows that the internal circuit connections of a bullet train. The aerodynamic shape is also important for the motion of train .The simulation and Its result is shown below-:

Main Simulation Results-:Optimization of the suspension parameters has been made by the calculation of responses of the vehicle to the above track input. With the optimized suspension parameters, a typical accelerations of car body are illustrated in Figure 8, and the gap disturbances between magnet and track are illustrated in Figure 9. The time domain results for individual control and modal control are approximately similar.

Compared to conventional trainsMajor comparative differences between the two technologies lie in backward compatibility, rolling resistance, weight, noise, design constraints, and controlsystems. Backwards CompatibilityMaglev trains currently in operation are not compatible withconventional track, and therefore require all new infrastructure for theirentire route. By contrast conventional high speed trains such as theTGV are able to run at reduced speeds on existing rail infrastructure, thus reducing expenditure where new infrastructure would beparticularly expensive (such as the final approaches to city terminals),or on extensions where traffic does not justify new infrastructure. EfficiencyDue to the lack of physical contact between the track and the vehicle,maglev trains experience no rolling resistance, leaving only airresistance and electromagnetic drag, potentially improving powerefficiency. WeightThe weight of the large electromagnets in many EMS and EDS designsis a major design issue. A very strong magnetic field is required tolevitate a massive train. For this reason one research path is usingsuperconductors to improve the efficiency of the electromagnets, andthe energy cost of maintaining the field. NoiseBecause the major source of noise of a maglev train comes fromdisplaced air, maglev trains produce less noise than a conventionaltrain at equivalent speeds. However, the psychoacoustic profile of themaglev may reduce this benefit: A study concluded that maglev noiseshould be rated like road traffic while conventional trains have a 5-10dB "bonus" as they are found less annoying at the same loudnesslevel.DesignComparisons Braking and overhead wire wear have caused problemsfor the Fastech 360 railed Shinkansen. Maglev would eliminate theseissues. Magnet reliability at higher temperatures is a countervailingcomparative disadvantage (see suspension types), but new alloys andmanufacturing techniques have resulted in magnets that maintain theirlevitational force at higher temperatures.As with many technologies, advances in linear motor design haveaddressed the limitations noted in early maglev systems. As linearmotors must fit within or straddle their track over the full length of thetrain, track design for some EDS and EMS maglev systems ischallenging for anything other than point-to-point services. Curves mustbe gentle, while switches are very long and need care to avoid breaksin current. An SPM maglev system, in which the vehicle permanentlylevitated over the tracks, can instantaneously switch tracks usingelectronic controls, with no moving parts in the track. A prototype SPMmaglev train has also navigated curves with radius equal to the lengthof the train itself, which indciates that a full-scale train should be able tonavigate curves with the same or narrower radius as a conventionaltrain. Control SystemsEMS Maglev needs very fast-responding control systems to maintain astable height above the track; this needs careful design in the event ofa failure in order to avoid crashing into the track during a powerfluctuation. Other maglev systems do not necessarily have thisproblem. For example, SPM maglev systems have a stable levitationgap of several centimeters.

ADVANTAGES OF MAGLEV TRAIN-: Faster tripsHigh peak speed and high acceleration/braking enable average speedsthree to four times the national highway speed limit of 65 mph (30 m/s)and lower door-to-door trip time than high-speed rail or air (for tripsunder about 300 miles or 500 km).And still higher speeds are feasible.Maglev takes up where high-speed rail leaves off, permitting speeds of250 to 300 mph (112 to 134 m/s) and higher. High reliabilityLess susceptible to congestion and weather conditions than air orhighway. Variance from schedule can average less than one minutebased on foreign high-speed rail experience. This means intra- andintermodal connecting times can be reduced to a few minutes (ratherthan the half-hour or more required with airlines and Amtrak at present)and that appointments can safely be scheduled without having to takedelays into account. Petroleum independenceWith respect to air and auto as a result of being electrically powered.Petroleum is unnecessary for the production of electricity. In 1990, lessthan 5 percent of the Nation's electricity was derived from petroleumwhereas the petroleum used by both the air and automobile modescomes primarily from foreign sources. Less pollutingWith respect to air and auto, again as a result of being electricallypowered. Emissions can be controlled more effectively at the source ofelectric power generation than at the many points of consumption, suchas with air and automobile usage. Higher capacity than airAt least 12,000 passengers per hour in each direction with potential foreven higher capacities at 3 to 4 minute headways. Provides sufficientcapacity to accommodate traffic growth well into the twenty-first centuryand to provide an alternative to air and auto in the event of an oilavailability crisis. High safetyBoth perceived and actual, based on foreign experience. ConvenienceDue to high frequency of service and the ability to serve centralbusiness districts, airports, and other major metropolitan area nodes. Improved comfortWith respect to air due to greater roominess, which allows separatedining and conference areas with freedom to move around. Absence ofair turbulence ensures a consistently smooth ride. MaintenanceDue to the non-contact technology, the cost of vehicle and guidewaymaintenance is very low.In the event of a malfunction of one of the propulsion and controlcomponents, the remaining components can assume itsresponsibilities, thereby ensuring a high overall system availability. If anelectronic component group in the vehicle fails, the high redundancyconcept guarantees that the vehicle will reach the next destination.Here the vehicle can be taken out of operation, the defectivecomponent quickly replaced, and then be available as reserve.The guideway is inspected and monitored by maintenance vehiclesfrom the guideway. These are provided with measuring systems todetect any changes in the position of the guideway equipment (such asstator packs, cable windings, and guidance rails) and with opticalsystems using digital photo interpretation to check the condition of thesurfaces, e.g. for corrosion. In addition, evaluation of the sensor dataobtained in daily operation allows the maintenance personnel to detectany changes in the position of the guideway and to implementcorrective measures in a timely, efficient manner. An access road alongthe guideway is not required for maintenance purposes.

FIG-:Maintenance FactoryEFFECT OF SOUND SOURCES ON TRAINFuture ExpansionsIn the far future Maglev technology are hoped to be used to transport vast volumes of water to far regions at a greater speed eliminating droughts. Far more, space is an open door to maglev trains to propel spaceshuttle and cargo into space at a lower cost. Artists illustration of StarTram, a magnetically levitated low-pressure tube, which can guidespacecraft into the upper atmosphere. Scientists hope future technologies can get the train to operate at a6000km/h, since theoretically the speed limit is limitless. But still its a long way to go. Toshiba Elevator and Building Systems Corp have developed theworlds first elevators controlled by magnetic levitation available asearly as 2008.Using maglev technology capable of suspending objectsin mid-air through the combination of magnetic attraction and repulsion they promise quieter and more comfortable travel at up to 300m per minute, some 700m per-minute. Thus, active collaboration and future joint ventures from all international bodies holds the future of these trains.propulsion of space shuttle

CONCLUSIONThis report gives us an insight about the principle of maglev as well as itsapplication in running maglev trains. Also, the intricate complexities of themaglev technology have been explained. Its implementation in the variouscities of the world and its innumerable advantages just take it a step closer tobeing the future of transportation. Maglev trains are soon going to be the newway of transportation. Just a few obstacles are in the way, but with somemore improvisations nothing is impossible. With no engine, no wheels, nopollution, new source of energy, floating on air, the concept has taken tens ofyears to develop and just recently its true capabilities have been realized.Competing planes with speed, ships with efficiency, traditional trains withsafety, and cars with comfort, it seems like a promising means of transport.Maglev trains are environment friendly; noise pollution is minimized becausethere is no wheel to rail contact (frictionless). A maglev train operating at150mph is inaudible to a person standing 25 miles away. The systemencourages land conservation, which is especially useful where land is costlyor unavailable. Tracks for the trains are easily built on elevated platforms; thisprovides opportunity for construction and development underneath andprevents land dissection and also reduces animal collisions. This assertioncan prove useful in constructing guide ways for maglev trains acrossresidential areas, schools, religious places, tourist spots, etc. However, thecost of construction of these trains runs into billions of dollars. The high costof these trains is the only deterrent factor which is preventing the train frombeing executed everywhere. Continued research in this field along with activeinterest from the various governments in the world can reduce the costingconsiderably with cheaper options not compromising on the safety.

GLOSSARY AC CurrentIn alternating current (AC, also ac) the movement (or flow) of electric charge periodically reverses direction. An electric charge would for instance move forward, then backward, then forward, then backward, over and over again. AmortizationTo decrease an amount gradually or in installments, especially in order to write off an expenditure or liquidate a debt ChassisA chassis consists of a framework that supports an inanimate object. Eddy currentAn eddy current is an electrical phenomenon caused when a conductor is exposed to a changing magnetic field due to relative motion of the field source and conductor; or due to variations of the field with time. FerromagnetismFerromagnetism is the basic mechanism by which certain materials (such as iron) form permanent magnets and/or exhibit strong interactions with magnets; it is responsible for most phenomena of magnetism encountered in everyday life (for example, refrigerator magnets). FluxThe lines of force surrounding a permanent magnet or a moving charged particle. Flux Densityflux density is the amount of magnetic flux per unit area of a section,perpendicular to the direction of flux. Gradienta graded change in the magnitude of some physical quantity or dimension. Groove. LevitatingTo rise or cause to rise into air and float in apparent defiance of gravity. Levitation, MagneticSupport technology that keeps a vehicle separated from its guideway by riding a surface of magnetic force.Lenz Law"An induced current is always in such a direction as to oppose the motion or change causing it". PropulsionIt means to push forward or drive an object forward. A propulsion system is a machine that produces thrust to push an object forward. PsychoacousticA branch of science dealing with the perception of sound, the sensations produced by sounds and the problems of communication.

BIBLIOGRAPHY Superconducting Levitation: Applications to Bearings and Magnetic Transportation, Francis Moon, Wiley & Sons, New York, 1994. Magneto-Solid Mechanics, Francis Moon, Wiley & Sons, New York, 1984. Electromagnetics, J.D. Kraus, McGraw Hill Companies, New York, 1992, p. 288.