GPS Applications:

GPS, which is definitely Global Positioning System, is pretty  well known these days. Most of the non technical people must have heard of it because of new GPS enable Smartphones like iPhone and Androids. GPS tracking system is application of GPS in real physical life.

1. GPS is at the heart of the system called as fleet tracking. Linguistically, fleet could be a group of vehicles. Many companies, these days, needs to keep many vehicles for their daily usage. Fleet tracking can find its applications over here. It will help company to get statistical as well run-time data of the vehicles locations, speed, availability and many more. This report can be used to develop the routes and the plans that are much efficient.
2. GPS vehicle tracking have another important advantage, theft safe. Many cases have happened over the world in which vehicles tracked by GPS recovered from theft within few hours. This had been possible due to GPS’s ability to give the exact location of vehicle.
3. As I said before, GPS is no more a forbidden fruit like thing. iPhone and Android Apps ar doing great. They can connect to car systems and help to get the updated reports.
4. Response time of your service can drop significantly by making fair use of GPS.
5. With introduction of Google maps like applications, using GPS becomes even more easy, entertaining and handy.
6. As GPS is invented by defense, it tactical use is for them.
7. Aviation industry is one which can rely on GPS for spotting exact position of the planes and other targets.
8. Natural resource management needs GPS for better management of the things.

Thank You.

Related posts:

1. Total GPS – A Positioning System by Using Satellites
2. DGPS – Positioning System with Satellite and Fixed Ground Station

This Article Will Try To Answer Following Questions:

1. Firstly, what is GPS?
2. Need For Differential GPS?
3. Working Principle of DGPS.
4. How DGPS does actually work?
5. What is accuracy of DGPS and what are the factors that hamper the DGPS results’ accuracy?
6. DGPS compared with GPS?
7. Where are the places where DGPS can make the difference?
8. References.

Differential Global Positioning System (DGPS):

DGPS and GPS are bit different but inseparable concepts. So, you must have brief hint about GPS. GPS is Global Positioning System which is basis of the DGPS. DGPS is enhancements to GPS. To understand GPS in more detail read Everything About Global Positioning System.

Why DGPS Evolved?

One line answer to this question would be “Out of Need!” Yes, need for better accuracy. GPS was a giant step into navigation and positioning. But due to some unavoidable limitations like satellite clock errors, satellite positioning errors, errors due to atmospheric layers and some errors which are inserted intentionally, GPS cannot be more accurate than certain extent. To overcome this DGPS is evolved.

Working Principle of DGPS:

The secret behind the better accuracy of DGPS over GPS is reference station.

Actually, What Happens Out There:

For DGPS to work, there are 24 satellites orbiting the earth at about 20000 km away. Each of the satellite is mounted with the atomic clock and radio transmitter. They emit timing signal which can be received anywhere on the surface of earth.
Such signals, from 3 different satellites are available anywhere on earth. So, the signal is analyzed by GPS receiver located on the ground. This receiver calculates the time taken by the timing signal to reach there. Form that time lag; it can calculate the distance of the satellite from that position.
Satellite positions are very precisely monitored from the ground centers. So, there positions are pretty well known. From all this data, receiver can calculate its location on earth.
Up till now this working is exactly like GPS.
DGPS comes in action with a reference station mounted on the ground. This reference station plays both roles Receiver and Transmitter.
Reference station is carefully fixed at a location so its own location is perfectly known. Then this reference station receives the satellite signal and calculates its own position. It calculates the errors for each satellite with help of its actual position and calculated position. And then it transmits this error in the form of error signal.
This error signal is received by the DGPS receivers in its area. Receivers and reference station are near enough so that they receive signals from same satellite. Finally, DGPS receiver calculates its position with help of 3 satellite signals and one error signal.

Accuracy of DGPS:

DGPS is much more accurate than GPS. Normal users GPS can give the result within area of 100 square meters while military GPS can be accurate up to 15 square meters. DGPS can be way more accurate than Military GPS with accuracy of 3 square meters.

Potential Uses of GPS and DGPS:

Aviation:

DGPS and GPS both can be used very effectively in Aviation. They are useful for locating the Aircrafts then landing the aircrafts. DGPS can be good guiding system for automated planes and vehicles which are supposed to use some predefined paths.

Public Safety:

When we think of some fire fighting scenario response time for fire brigade is very small as well as important. Same is for Police and Army too. With these systems in action, they can exactly know where they are and where they want to go.

Natural Resource Management:

Here, GPS can become a survey tool which can be used for keeping the records for areas of forest, mines, fishing areas, area of forest and many more.

Apart from all above uses DGPS and GPS are used for Agricultural Use, Offshore Exploration, Transportation, Shipping etc.

Reference:

This article is published with help of book “Differential GPS Explained” written by Jeff Hurn and Published By Trimble Navigation. This book is good grounding for Differential Global Positioning System Concept.

For detailed study on GPS please read book “GPS- A Guide To The Next Utility”.

Related posts:

1. Total GPS – A Positioning System by Using Satellites

This Article Will Clear Following Questions about GPS:

1. What is Positioning?
2. What is GPS? How did GPS concept was evolved?
3. What is the principle of working of GPS?
4. How does GPS calculates its location on earth?
5. What are factors affecting the results of GPS? And How accurate GPS can be?
6. Where in world the GPS is used?
7. Updates of subject GPS?

Positioning In Short:

Positioning System is one by which the USER, which could be single user or airplane or some machine or similar kind of thing, gets the location where he/she/it is currently present.

What is GPS?

Basically, GPS is Global Positioning System. It is Navigation Technology. So, it is the system which defines the position on Earth one is currently at! This position is absolute and can not be confused with any other.

How GPS was Born?

GPS was born for fulfilling the need of United States Department of Defense. They needed the positioning system that will work all over the earth with the same reliability. This Defense invention is available all over the world for Defense as well as Civilian use and absolutely free.

GPS in Abstract:

So, how this GPS actually works? Global Positioning System works on behalf of 24 satellites orbiting at about 20000km around the earth. These satellites are monitored from the ground stations and hence a ground station knows their positions exactly well. For any positioning system will need the reference points. Here in GPS, these satellites acts as perfect reference points and with some mathematics and technology we with our GPS receiver can calculate our position.

How GPS Exactly Works

GPS works on very simple principle. Here it given step by step.

For GPS, 24 satellites orbit the earth at about 20000 km from earth surface. So that, at any position on earth surface you can have access to at least 3 satellites’ signal.
Each of the satellite keeps on sending the timing signal in the form of radio waves. These radio waves take some time to reach from satellite to GPS receiver.
As speed of Radio Waves is known, Time required T can be used to calculate the distance of that position from the satellite.

Distance (meter) = Speed of Radio Waves (meter/second) * Time Required (second)
D = ( 3 * 10  ^  8 ) * T

In this way, receiver exactly knows the distance of that position from particular satellite. And same is calculated for other two satellites too.
So, now receiver exactly knows 3 distances from 3 satellites whose position is exactly known. From that its own position can be very easily calculated.

Factors Affecting the Accuracy of GPS

There are many factors which affect the accuracy of GPS significantly.

Satellite Clocks:

Satellites are mounted with extremely precise atomic clocks but still they are not error free. They introduce a little error which affects the GPS accuracy.

Satellite Orbits:

Theoretically, satellites can follow unique orbit. But in practical situation satellite are a bit offset from their desired position or orbit which affects the accuracy of GPS.

Atmosphere:

In above section, we took the speed of Radio Waves as 300000 kilometer/sec. But this speed is applicable for absolute vacuum only. It changes as with the medium the waves are passing through. Here in case of GPS this medium is our atmosphere which is made up from so many different gases and layers. This also affects the accuracy of GPS.

Multipath Errors:

As name suggests, it occurs due to multiple reflections of the signal departed from the satellite. This error causes GPS receiver to receive noisy signal.

Receiver Error:

Again it’s very simple. Receiver is not perfect. So, it’s got its own errors that will be introduced into the calculations.

Selective Availability:

This is error which affects the GPS performance at maximum level. This error is generated and introduced by U.S. Department of Defense in satellite signal. There is a security reason behind it. With error free GPS reading satellite position can be tracked and this will make those satellites prone to some kind of attacks.

Accuracy of GPS:

With all these errors, GPS can give the accurate results within up to 100 meters which is good enough for the civilian use. For Defense application this accuracy can be improved by removing Selective Availability error which is up to 15 meter.

To improve this accuracy GPS took one step forward with DGPS which is Differential Global Positioning System.

Reference:

All the above information is published with help of book “Differential GPS Explained” written by Jeff Hurn and Published By Trimble Navigation.

For more study on GPS topic you may like to read book “GPS- A Guide To The Next Utility”.

No related posts.

There are 3 main types of cooling. First is film cooling. Second convection cooling and third is transpiration cooling method. Here we will see some facts about transpiration cooling method.

Principle of Transpiration Cooling:

1. In transpiration cooling, coolant coming from the reservoir flows through the porous wall towards the hot gas side wall towards the hot gas side wall surface. Passing through the porous structure the coolant absorbs the heat flux conducted into the solid material of the wall. At steady state operation a thermal equilibrium between the coolant and the solid wall is reached.
2. The coolant forms a film on the hot gas side surface. The coolant film partially absorbs the convective wall heat flux and thus reduces the heat flux conducted into wall to a certain amount, just like actual film cooling. The heated coolant at the film surface is transported downstream by the momentum of the hot gas flow, continuously replaced with fresh coolant flowing out of the wall.

Scope of Transpiration Cooling Method:

Transpiration cooling is a novel and efficient method of allowing the turbine blades and other parts within the hot section to operate at much higher turbine inlet temperatures.

By using a gaseous cooling medium, transpiration cooling could provide a higher cooling effect and larger coolant coverage than film cooling in the leading stagnation region, and on the side of the specimen at the same coolant injection flow rates.

But in the trailing stagnation region, the traditional coolant injection method through discrete film holes might be better than transpiration cooling, especially for turbine blades with thin trailing edges.

Finally, some of the disadvantages & problems associated with transpiration cooling are: Many of highly porous materials lack strength & machinability, in addition many of porous material exhibits a tendency to oxidized rather quickly, causing the pores to be blocked by oxide film & causing a coolant flow through the material to be reduced, resulting in material failure. Because of these problems, there has been a shift towards investigating better cooling schemes.

The transpiration of coolant fluid has great cooling effectiveness as a result of decrease of surface temperature and heat flux, as transpired fluid injected into the outer flow cools the surface as well as creates a moderate temperature gradient near the surface.

Increase of back face pressure corresponding to increase of transpiration mass flow causes the lower surface temperature and smaller heat flux. The cooling effectiveness per mass transpiration rate based on decrease of surface temperature is improved by smaller porosity, which shows the superiority of smaller porosity material for practical use.

Applications of Transpiration Cooling:

1. Fuel injection apparatus in Ram Jet engine needs good cooling system as it is present near to combustion in combustion chamber. Transpiration cooling performs good job in this phenomenon.

2. In thermal barrier coating transpiration cooling is provided successfully.

3. One of the very important application of transpiration cooling is cooling of turbine blades. This is widely used today for effective cooling of blades which in turn improves the life of turbine performance.

4. Transpiration cooling is also used in the rocket engines.

5. Even nature uses the principle of transpiration cooling in plants. T.C. phenomenon takes place at leaves of plants.

Related posts:

1. Cooling Needs In Industry
2. Hybrid Solar Desiccant Cooling System

Seminar Guidelines for Carbon Nanotube:

Carbon nanotube information is given below. For making the seminar of Carbon Nanotube some guidelins are given below:

1. Definition of Carbon Nanotube, which includes the brief introduction of carbon nanotube.
2. History, showing the technological advances in nanotechnology and importance of carbon nanotube among them.
3. Manufacturing techniques of carbon Nanotubes.
4. Special Properties.
5. Current and Future Applications.
6. Standard References.

What is Carbon Nanotube?

First of all, Carbon nanotube is being under studies from many years, about 1991. Single Walled carbon nanotube is New Form of Carbon. It is made by rolling up the single graphite sheet to narrow and long tube closed at both sides.

Carbon is most amazing element on the earth. This form (carbon nanotube) form of carbon shows many physical and chemical alterations and hence have high potential in various physical and chemical properties.

History  of Carbon Nanotube:

As mentioned before Carbon Nanotube is first invented in about 1991. From that breakthrough it have gone through many studies which is mentioned below:

1. 1991: Discovery of Multiwall Carbon Nanotube.
2. 1993: Synthesis of Single Wall Nano Tubes.
3. 1995: Invention of nanotube as Field Emitter.
4. 2000: Thermal Conductivity of Nanotube.
5. 2001: Integration of Carbon Nanotube in Electronics.

And so on….

Special Properties of Carbon Tubes:

• Polymerization: It is property of material, here Carbon Nanotube, to form the 1D, 2D and 3D polymer structure.

• Superconductivity: Carbon Nanotube is  one-dimensional fibers exhibit electrical conductivity as high as copper, thermal conductivity as high as diamond.
• Ferromagnetism:
• Non-Linear Optical Activity:
• Metallic Conductivity: Nanotubes can be either electrically conductive or semi conductive, depending on their helicity.

Moreover, the physical Strength of carbon nanotube is 100 times greater than the steel and this much strength is delivered with 1/6th of the weight of steel.

Current Applications of Carbon Nanotubes:

Carbon Nano-tubes are extending in ability to fabricate  devices such as:

1. Molecular Probes.
2. Pipes.
3. Wires.
4. Bearings.
5. Springs.
6. Gears.
7. Pumps etc.

Future Applications for Carbon Nanotubes:

We have seen the amazing properties of Carbon Nanotubes. Due to their exceptional behaviour they have very high potential to be used in future. Some of them are listed below:

1. Molecular Transistors.
2. Field Emitters.
3. Smaller and Low Weight components mainly for aircrafts and spacecrafts.
4. Space Elevators.
5. Parts for Electronics.

References:

1. http://en.wikipedia.org/wiki/Carbon_nanotube

2. http://physicsworld.com/cws/article/print/1761

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Today, we are using the conventional fuels like coal, petroleum products, LPG etc. on very high scale for the purpose of industrialization, transportation, domestic purposes etc. The emissions due to use of conventional fuels has lead to many problems like air pollution, water pollution and most recent is the global warming. Another important problem is the high cost of these fuels. Again, all these conventional fuels, we have, are limited in nature.

All these problems regarding to the conventional fuels and there sources have lead the engineers to think about another sources of energy. That is why the non conventional fuel sources (Renewable Energy Sources) have got a lot of importance today. They include Wind Energy, Tidal Energy, Geothermal Energy, Solar Energy etc.

Solar Energy is one of the important source of energy from the non conventional energy sources. Maximum places in the world get the adequate amount of the solar energy, in short, it is easily available, it is free and will be long lasting. Today, we know many appliances working on Solar Energy such as Photovoltaic cell, Solar Water Heater, Solar Water Distillator, Solar Cooker etc.

NASA, ERAST program under which solar aircraft research was done. [More information can be found on NASA website ].

The Brief Developments in various Models of Solar Aircraft are as belows:-

1. Pathfinder:::100feet wingspan and 6 propellers operated.
2. Pathfinder Plus:::120 feet wingspan and 8 propellers operated.
3. Centurion:::206 feet wingspan and 14 propellers operated.
4. Helios Prototype for high altitude configuration:::247 feet wingspan and 14 propellers
5. Helios Prototype for Long endurance configuration:::247 feet wingspan and 10 propellers.

Advantages of Solar Aircraft:

1. Uses Solar energy which is long lasting, non polluting and easily available source of energy.
2. This can work like Relocattable satellite in the sky (it can do work like satellite as hovers at very high height.)
3. Operated remotely so no danger of human life.
4. Can be sent to missions lasting many days, months as no need to re-fuel it.
5. Hovers much higher altitudes than normal air traffic. So no air traffic problems.

For constructional details of solar aircraft see Construction of The Solar Aircraft

Limitations:

1. Can not carry heavy loads.
2. Very high cost of construction (Mere silicon solar cells of Helios Prototype costs upto $9 million!).

Practical Applications:

1. Instrument for crop management, fisheries, coral reefs, forests etc.
2. For monitoring the changes in weather as fly much above the normal weather conditions.
3. Can monitor strength and change in directions of hurricanes as fly above them easily.
4. In future, can act as space tower and provide service like high speed broadband etc.
5. Aircraft made with same technology can be sent to other planets to make space research.

References for Study of The Solar Aircraft:

[1] Anthony J. Colozza, Convective Array Cooling for Solar Power Aircraft –NASA –2003/212084.
[2] http://www.nasa.gov/centers/dryden/news/FactSheets/FS-034-DFRC.html

[3] http://en.wikipedia.org/wiki/Helios_Prototype

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