Showing posts with label TECHNICAL PROJECTS. Show all posts
Showing posts with label TECHNICAL PROJECTS. Show all posts

Saturday, February 16, 2013

Curious about Curiosity

Sunday, December 2, 2012

DRDO Interview Questions for Electrical Engineers


Ramana my Friend's DRDO interview Questions:

Chairman:

1. What are the various experiments you have done in your machines lab
2. How the vibrations are produced from mobile phone when it is in that mode

Departmental Expert-1:

1. Why your eyes are in red colour, don't you have enough sleep yesterday night
2. what is your favorite subject
3. What is meant by zpf... this term is related to which machine
4. What is meant by reluctance motor
5. write the expression for power developed in salient pole synchronous motor?
6. what is meant by load angle in detail
7. Can you explain hunting breafly..?
8. Is there any method to reduce hunting...?
I think you studied power system analysis in your B.Tech....not power systems, power system analysis

9. what are the various quantities required for design of power system
10. Can you tell me the method for power system stability analysis
He gives clue for above question
11. Explain equal area criterion analysis method

Departmental expert-2:

1. this question related to communication subject
2. what is meant by stepper motor
3. how the steps can achieve
4. what is meant by BLDC motor
5. what is the constructional and operational difference between BLDC motor and DC motor
6. without the brushes and commutator how can you achieve the current reversal?
for the above question Departmental Expert-1 gives 50% answer as clue...
7. what is the purposes of commutator in DC machines
8. In diesel engine trains how the exact system is there inside
9. How can we get the supply for fans and lights in trains
10. Name the special generator used for above...?
for this question departmental expert-1 gives full answer

External expert:

1. instead of using AC transmission why we are using HVDC
2. What is the main adv. and dis adv. of HVDC
3. can you learn about the earth fault circuit breaker in houses
4. what is meant by MCB? how it works? which type of CB it is?

Departmental expert-1:

1. apart from the losses, cost etc etc..... the advantage of HVDC over any other....

..................................@@@000@@@...............................

Lastly the departmental expert-1 asks Well Mr. Ramana suppose if you are selected in this job, afterwards you got
other job based on B.Tech (example in ISRO that is also a R&d org.)then what do you do....

K@run@

Thursday, July 5, 2012

HIGGS BOSAN---Proton sub particles

Great invention for the decade which gonna change the future......Higgs Bosan was discovered after blasting the protons......many scientists strived so hard for 50 years for this....including our indians....Named as Higgs BOSan after the Indian scientist BOSE
K@run@

Wednesday, November 30, 2011

Nuclear weapons


Nuclear weapons
A few words about nuclear weapons technology..


Fission weapons

Nuclear weapons exploit two principle physical, or more specifically nuclear, properties of certain substances: fission and fusion.
Fission is possible in a number of heavy elements, but in weapons it is principally confined to what is termed slow neutron fission in just two particular isotopes:235U and 239Pu. These are termed fissile, and are the source of energy in atomic weapons. An explosive chain reaction can be started with relatively slight energy input (so-called slow neutrons) in such material.
Pu239Ga.jpg (6513 bytes)
An actual 239Pu ingot, alloyed with gallium for improved physical properties
Isotopes are 'varieties' of an element which differ only in their number of neutrons. For example, hydrogen exists as 12H and 3H -- different isotopes of the same chemical element, with no, one, and two neutrons respectively. All the chemical properties, and most of the physical properties, are the same between isotopes. Nuclear properties may differ significantly, however.
The fission, or 'splitting' of an atom, releases a very large amount of energy per unit volume -- but a single atom is very small indeed. The key to an uncontrolled or explosive release of this energy in a mass of fissile material large enough to constitute a weapon is the establishment of a chain reaction with a short time period and high growth rate. This is surprisingly easy to do.
Fission of 235U (uranium) or 239Pu (plutonium) starts in most weapons with an incident source of neutrons. These strike atoms of the fissile material, which (in most cases) fissions, and each atom in so doing releases, on average, somewhat more than 2 neutrons. These then strike other atoms in the mass of material, and so on.
If the mass is too small, or has too large a surface area, too many neutrons escape and a chain reaction is not possible; such a mass is termed subcritical. If the neutrons generated exactly equal the number consumed in subsequent fissions, the mass is said to be critical. If the mass is in excess of this, it is termed supercritical.
Fission (atomic) weapons are simply based on assembling a supercritical mass of fissile material quickly enough to counter disassembly forces.
The majority of the energy release is nearly instantaneous, the mean time from neutron release to fission can be of the order of 10 nanoseconds, and the chain reaction builds exponentially. The result is that greater than 99% of the very considerable energy released in an atomic explosion is generated in the last few (typically 4-5) generations of fission --  less than a tenth of a microsecond.*
This tremendous energy release in a small space over fantastically short periods of time creates some unusual phenomena -- physical conditions that have no equal on earth, no matter how much TNT is stacked up.
Plutonium (239Pu) is the principal fissile material used in today's nuclear weapons. The actual amount of this fissile material required for a nuclear weapon is shockingly small. 
Below is a scale model of the amount of 239Pu required in a weapon with the force that destroyed the city of Nagasaki in 1945:
Pu32inch.jpg (4643 bytes)
In the Fat Man (Nagasaki) weapon design an excess of Pu was provided. Most of the remaining bulk of the weapon was comprised of two concentric shells of high explosives. Each of these was carefully fashioned from two types of explosives with differing burn rates. These, when detonated symmetrically on the outermost layer, caused an implosion or inward-moving explosion.
The two explosive types were shaped to create a roughly spherical convergent shockwave which, when it reached the Pu 'pit' in the center of the device, caused it to collapse. 
The Pu pit became denser, underwent a phase change, and became supercritical. 
A small neutron source, the initiator, placed in the very center of this Pu pit, provided an initial burst of neutrons --  final generations of which, less than a microsecond later, saw the destruction of an entire city and more than 30,000 people..
Nearly all the design information for weapons such as these is now in the public domain; in fact, considering the fact that fission weapons exploit such a simple and fundamental physical (nuclear) property, it is no surprise that this is so. It is more surprising that so much stayed secret for so long, at least from the general public. 
A neutron reflector, often made of beryllium, is placed outside the central pit to reflect neutrons back into the pit. A tamper, often made of depleted uranium or238U helps control premature disassembly. Modern fission devices use a technique called 'boosting' (referred to in the next section), to control and enhance the yield of the device.
Today's nuclear threat lies mostly in preventing this fissile special nuclear material (often referred to as SNM) from falling into the wrong hands: once there, it is a very short step to construct a working weapon.
What we do now to keep these devices out of the hands of groups like Al-Qaeda is vital to civilized peoples.
abomb.jpg (13766 bytes)A schematic of a hypothetical 'boosted' fission weapon
(showing unnecessary 235U)

trinity.jpg (22048 bytes)
The gadget device used in the Trinity test: the world's first nuclear weapon test. 
Note spherical geometry and the HE detonator arrangement. New Mexico, 21KT, 1945.
grable.jpg (16126 bytes)
Typical fission weapon, shortly after detonation at the Nevada test site, with roughly the same yield as the weapon that destroyed Hiroshima. Reddish vapor surrounding the plasma toroid includes intensely radioactive fission fragments and ionized nitrogen oxides from the atmosphere. (Grable, 15KT, 1953)



Fusion weapons

Fission weapons discussed above are ultimately limited in their destructive capability by the sheer size a subcritical mass can assume -- and be imploded quickly enough by high explosives to form a supercritical assembly. The largest known pure fission weapon tested had a 500 kiloton yield. This is some thirty-eight times the release which destroyed Hiroshima in 1945. Not satisfied that this was powerful enough, designers developed thermonuclear (fusion) weapons.
Fusion exploits the energy released in the fusing of two atoms to form a new element; e.g. deuterium atoms fusing to form helium, 2H + 2H = 4He2 , as occurs on the sun. For atoms to fuse, very high temperatures and pressures are required. Only fusion of the lightest element, hydrogen, has proven practical. And only the heavy isotopes of hydrogen, 2H (deuterium) and 3H (tritium), have a low enough threshold for fusion to have been used in weapons successfully thus far.
The first method tried (boosting) involved simply placing 3H in a void within the center of a fission weapon, where tremendous temperatures and high pressures were attendant to the fission explosion. This worked; contributing energy to the overall explosion, and boosting the efficiency of the Pu fissioning as well (fusion reactions also release neutrons, but with much higher energy). 
Because 3H is a gas at room temperature, it can be easily 'bled' into the central cavity from a storage bottle prior to an explosion, and impact the final yield of the device. This is still used today, and allows for what is termed 'dial-a-yield' capability on many stockpiled weapons.
Multistage thermonuclear weapons -- the main component of today's strategic nuclear forces -- are more complex. These employ a 'primary' fission weapon to serve merely as a trigger. As mentioned above, the fission weapon is characterized by a tremendous energy release in a small space over a short period of time. As a result, a very large fraction of the initial energy release is in the form of thermal X-rays. 
These X-rays are channeled to a 'secondary' fusion package. The X-rays travel into a cavity within a b28.jpg (8660 bytes)cylindrical radiation container. 
The radiation pressure from these X-rays either directly, or through an intermediate material often cited as a polystyrene foam, ablates a cylindrical enclosure containing thermonuclear fuel (shown in blue at left); this can be Li2H (lithium deuteride). 
Running along the central axis of this fuel is a rod of fissile material, termed a 'sparkplug'. 
The contracting fuel package becomes denser, the sparkplug begins to fission, neutrons from this transmute the Li2H into 3H that can readily fuse with 2H (the fusion reaction 3H + 2H has a very high cross-section, or probability, in typical secondary designs), heat increases greatly, and fusion continues through the fuel mass. 
A final 'tertiary' stage can be added to this in the form of an exterior blanket of 238U, wrapping the outer surface of the radiation case or the fuel package. 238U is not fissionable by the slower neutrons which dominate the fission weapon environment, but fusion releases copious high energy neutrons and this can fast fission the ordinary uranium. 
This is a cheap (and radiologically very dirty) way to greatly increase yield. The largest weapon ever detonated -- the Soviet Union's 'super bomb', was some 60 MT in yield, and would have been nearer 100MT had this technique been used in its tertiary. Again, to control the yield precisely, 3H may be bled from a separate tank into the core of the primary, as shown in the hypothetical diagram on the left of a modern thermonuclear weapon. 
This primary/secondary/tertiary or multistage arrangement can be increased -- unlike the fission weapon -- to provide insane governments with any arbitrarily large yield.
bravo.jpg (19917 bytes)
Rare photo of the actual shrimp device used in Castle Bravo. Note the cylindrical geometry, and the emergent spherical fission trigger on the right. Light pipes leading to ceiling are visible near the fission trigger and at two points along the secondary for transmitting early diagnostic information to remote collection points, before they themselves are destroyed. 

Note the 'danger, no smoking' sign at lower left. 15MT, 1954.

Fusion, or thermonuclear weapons, are not simple to design nor are they likely targets of construction for would-be terrorists today. 
Many aspects of the relevant radiation transport, X-ray opacities, and ultra-high T and D equations-of-state (EOS) for relevant materials are still classified to this day (though increasing dissemination of weapons-adaptable information from the inertially-confined fusion (ICF) area may change this in time). Keeping such information classified makes good sense.
romeo.jpg (9298 bytes)
Typical appearance of a thermonuclear weapon detonation -- from many miles away. 
(Castle Romeo, 7MT, 1954)

*Special techniques were required to record the fleeting moments of a weapon's initial detonation. One such method was theRapatronic camera, developed by Dr. Harold Edgerton. The images it created are bizarre. Check out our collection of Rapatronic photographs.

K@run@

Saturday, November 26, 2011

Mobile Charger Working

Mobile Phone Charger Insight2


When charger is connected with the AC supply, the LED starts glowing to indicate the proper operation of the charger.
 
Working
Latest mobile chargers are kind of power supply units that use the Switched Mode Power Supply (SMPS) technology. To understand the working phenomenon of a mobile charger, we need to understand the concept of Power Supply Unit (PSU). PSU is a device that transfers electrical energy from one end to another by changing its fundamental characteristics according to the requirements. Example of a PSU is an application that converts AC mains voltage to regulated DC voltage. PSUs can be of two types depending on the mode of operation – Linier and Switching.
 
In these switching mode chargers, energy transfer is done by continuously switching electrical components (inductor, capacitor, etc) on and off. We can control the output voltage/current by varying the duty cycle, frequency or the corresponding phase. Using the SMPS technology makes the chargers smaller and lighter by elimination of low frequency transformers. It also presents a greater efficiency than the conventional methods which uses bulky transformers.
 
The AC supply first enters through the line filters in the charger. Line filters are the kind of electronic filters that are placed between an electronic device and an external line to alter/attenuate the electromagnetic interference effect. Now filtered signal are made to pass through the full wave bridge rectifier circuit. Rectifier converts the AC voltage to DC.
 
Output DC voltage from rectifier circuit passes through the PFC (Power Factor Correction) circuit which operates power circuits at their maximum efficiency. Further the voltage signal is transferred to the pulse transformer that is a special type of transformer optimized to produce rectangular electrical pulses.
 
Pulse transformers are categorized into two categories – power and signal transformers. The one used here is a power transformer. It reduces the voltage level of the input power and gives a low voltage power that is exactly required to charge the battery.

K@run@

Wednesday, November 23, 2011

Capturing Electricity With a Shoe


Electric Slide Liquid moves between the bladders. As it does, the flow is converted into electricity. 

Humans are not very efficient. When we walk, we waste close to 20 watts of energy per second. Instead of turning all calories into lift or forward motion, we turn most of them into heat that’s quickly dissipated. So my colleagues and I came up with a way to harvest the wasted energy from human motion and convert it into about 10 watts of electricity.
Our device is based on a physical phenomenon called electrowetting: If you apply electrical voltage to certain liquids, the liquid moves. This means you have converted electrical energy (the current) to mechanical energy (the liquid in motion). We reversed the process, forcing liquid to move over electrodes. In the shoe, you have two flexible plastic bladders, one under the heel and the other under the toe. The bladders are filled with a mixture of oil and water and connected by a thin, snaking tube. When you step down on your heel, you compress the rear bladder, and several milliliters of liquid travel through the tube to the front bladder. Step on the toe, and the process is reversed.
The tube is lined with a thin film of electrodes, and as the liquid slides back and forth, the electrodes charge—electrowetting in reverse. A small battery stores the energy, and you can access that energy by way of a micro-USB port on the heel of the shoe. We also invented a way, like Wi-Fi, to transfer power from shoe to cellphone battery. Military or police might like having a regular supply of power, but I suspect most people wouldn’t be happy dealing with wires connected to their footwear.

K@run@

Wednesday, October 26, 2011

Projects for EEE,ECE,EIE

Sooxma Technologies is a leading organization providing excellent training in Projects and the latest innovative technologies. Sooxma Technologies works towards making the students understand the abstruse process of completing a project. Project Development has a sharp learning curve and the Professional acumen at Sooxma Technologies understands the intricacies of this learning curve. We teach students the technologies and make them do the project so that they can learn maximum and build a project having a good market value. Our expertises are present round the clock to cater to the needs of the students. Our excellent record for the 5 years is a manifestation of the quality of knowledge we impart to the students. We guide College Students in developing academic projects with next generation technologies. Currently we are focusing on Embedded/Microcontroller, Matlab, VLSI, DSP, DIP and Software based Student Projects. We Provide Latest Embedded Live Projects for Pre-Final and Final year BE/B.Tech, ME/M.Tech, MBA, BSc/MSc Electronics and Polytechnic/Diploma Students. Specially designed and developed projects as per student’s requirements. We prepare students for Project presentations. We assist Students in developing Complete Project Documentation.
K@run@

Saturday, February 26, 2011

Project in IIT's

Wow Indian institute of technology has given a great opportunity to all the top 10 rankers of their respective programs of every college in India. fellowship is also an added advantage. All we have to take care is period of project and guidance from a lecturer in IIT.