Monday, 19 December 2011

19/12/2011


Johny James 

After Barrel Roll easter egg, Google has now come up with another pleasant surprise. Stop whatever you are doing and and go to the Google homepage. Type in the words "Let it snow" in the search box and Google will surprise you.

As you type, you will find snowflakes falling in your browser. Snowflakes will fall from the top of your screen and slowly cover Google’s search results.
Ty now itself!!!! :)

reeshma ramesan

The Onset of Electrical Resistance,ScienceDaily 

When you first learned about electric currents, you may have asked how the electrons in a solid material move from the negative to the positive terminal. In principle, they could move ballistically or 'fly' through the solid, without being affected by the atoms or other charges of the material. But this actually never happens under normal conditions because the electrons interact with the vibrating atoms or with impurities. These collisions typically occur within an extremely short time, usually about 100 femtoseconds (10 -13seconds, or a tenth of a trillionth of a second). So the electron motion along the material, rather than being like running down an empty street, is more like trying to walk through a very dense crowd. Typically, electrons move only with a speed of 1m per hour, they are slower than snails.

Though the electrons collide with something very frequently in the material, these collisions do take a finite time to occur. Just like if you are walking through a crowd, sometimes there are small empty spaces where you can walk a little faster for a short distance. If it were possible to follow the electrons on an extremely fast (femtosecond) time scale, then you would expect to see that when the battery is first turned on, for a very short time, the electrons really do fly unperturbed through the material before they bump into anything. This is exactly what scientists at the Max-Born-Institute in Berlin recently did in a semiconductor material Extremely short bursts of terahertz light (1 terahertz = 10 12 Hz, 1 trillion oscillations per second) were used instead of the battery (light has an electric field, just like a battery) to accelerate optically generated free electrons in a piece of gallium arsenide. The accelerated electrons generate another electric field, which, if measured with femtosecond time resolution, indicates exactly what they are doing. The researchers saw that the electrons travelled unperturbed in the direction of the electric field when the battery was first turned on. About 300 femtoseconds later, their velocity slowed down due to collisions.

The present experiments allowed the researchers to determine which type of collision is mainly responsible for the velocity loss. Interestingly, they found that the main collision partners were not atomic vibrations but positively charged particles called holes. A hole is just a missing electron in the valence band of the semiconductor, which can itself be viewed as a positively charged particle with a mass 6 times higher than the electron. Optical excitation of the semiconductor generates both free electrons and holes which the terahertz bursts, our battery, move in opposite directions. Because the holes have such a large mass, they do not move very fast, but they do get in the way of the electrons, making them slower.

Such a direct understanding of electric friction will be useful in the future for designing more efficient and faster electronics, and perhaps for finding new tricks to reduce electrical resistance.


ANTO VARGHESE

PICmicrocontroller...
 The name PIC initially referred to "Peripheral Interface Controller".
PICs are popular with both industrial developers and hobbyists alike due to their low cost, wide availability, large user base, extensive collection of application notes, availability of low cost or free development tools, and serial programming (and re-programming with flash memory) capability.
   

Data space (RAM)

PICs have a set of registers that function as general purpose RAM. Special purpose control registers for on-chip hardware resources are also mapped into the data space. The addressability of memory varies depending on device series, and all PIC devices have some banking mechanism to extend addressing to additional memory. Later series of devices feature move instructions which can cover the whole addressable space, independent of the selected bank. In earlier devices, any register move had to be achieved via the accumulator.
To implement indirect addressing, a "file select register" (FSR) and "indirect register" (INDF) are used. A register number is written to the FSR, after which reads from or writes to INDF will actually be to or from the register pointed to by FSR. Later devices extended this concept with post- and pre- increment/decrement for greater efficiency in accessing sequentially stored data. This also allows FSR to be treated almost like a stack pointer (SP).
External data memory is not directly addressable except in some high pin count PIC18 devices.

CODE SPACE

The code space is generally implemented as ROM,EPROM or flash ROM. In general, external code memory is not directly addressable due to the lack of an external memory interface. The exceptions are PIC17 and select high pin count PIC18 devices.

Instruction set

A PIC's instructions vary from about 35 instructions for the low-end PICs to over 80 instructions for the high-end PICs. The instruction set includes instructions to perform a variety of operations on registers directly, the accumulator and a literal constant or the accumulator and a register, as well as for conditional execution, and program branching.
Some operations, such as bit setting and testing, can be performed on any numbered register, but bi-operand arithmetic operations always involve W (the accumulator), writing the result back to either W or the other operand register. To load a constant, it is necessary to load it into W before it can be moved into another register. On the older cores, all register moves needed to pass through W, but this changed on the "high end" cores.
PIC cores have skip instructions which are used for conditional execution and branching. The skip instructions are 'skip if bit set' and 'skip if bit not set'. Because cores before PIC18 had only unconditional branch instructions, conditional jumps are implemented by a conditional skip (with the opposite condition) followed by an unconditional branch. Skips are also of utility for conditional execution of any immediate single following instruction.
The 18 series implemented shadow registers which save several important registers during an interrupt, providing hardware support for automatically saving processor state when servicing interrupts.
In general, PIC instructions fall into 5 classes:
  1. Operation on working register (WREG) with 8-bit immediate ("literal") operand. E.g. movlw (move literal to WREG), andlw(AND literal with WREG). One instruction peculiar to the PIC is retlw, load immediate into WREG and return, which is used with computed branches to produce look up tables.
  2. Operation with WREG and indexed register. The result can be written to either the Working register (e.g. addwf reg,w). or the selected register (e.g. addwf reg,f).
  3. Bit operations. These take a register number and a bit number, and perform one of 4 actions: set or clear a bit, and test and skip on set/clear. The latter are used to perform conditional branches. The usual ALU status flags are available in a numbered register so operations such as "branch on carry clear" are possible.
  4. Control transfers. Other than the skip instructions previously mentioned, there are only two: goto and call.
A few miscellaneous zero-operand instructions, such as return from subroutine, and sleep to enter low-power mode.


AJAY PAUL

The Lamborghini Aventador LP700-4 is a two-door, two-seater sports car publicly unveiled by Lamborghini at the Geneva Motor Show on 28 February 2011, five months after its initial unveiling in Sant'Agata Bolognese.[2] Internally codenamed LB834,[3] the Aventador was designed to replace the ten-year-old Murciélago as the new flagship model in the Lamborghini line-up starting in 2011.[4] Soon after the Aventador unveiling, Lamborghini announced that it had already sold over 12 months of the production vehicles, with deliveries starting in the second half of 2011.[5] The suggested retail price is €255,000 in Europe, £201,900 in the UK and $379,700 in the U.S.[6][7][8]

http://www.aventador.com/index-eng.html

Arun Jose

Team develops technique for removing metals from water



It is reported that the team successfully reduced cadmium, copper and nickel concentrations in contaminated water samples and returned them to standards deemed acceptable by the US government.The method, called the cyclic electrowinning/precipitation (CEP) system, is reported to collate trace-heavy metals in water by increasing their concentration, so that a proven metal-removal technique can take over.The CEP system involves two main units: one to concentrate the cations and another to turn them into stable, solid-state metals and remove them.
In the first stage, the metal-laden water is fed into a tank in which an acid (sulphuric acid) or base (sodium hydroxide) is added to change the water’s pH, effectively separating the water molecules from the metal precipitate, which settles at the bottom. The ‘clear’ water is syphoned off and more contaminated water is brought in.
The pH swing is applied again, first redissolving the precipitate and then reprecipitating all the metal, increasing the metal concentration each time.
This process is repeated until the concentration of the metal cations in the solution has reached a point at which electrowinning can be efficiently employed.
When that point is reached, the solution is sent to a second device, called a spouted particulate electrode (SPE). This is where the electrowinning takes place and the metal cations are chemically changed to stable metal solids, so they can be easily removed.
The cleaner water is returned to the precipitation tank, where metal ions can be precipitated once again. Further cleaned, the supernatant water is sent to another reservoir, where additional processes may be employed to further lower the metal-ion concentration levels. These processes can be repeated in an automated, cyclic fashion as many times as necessary to achieve the desired performance, such as drinking-water standards.
Joseph Calo, professor of engineering at Brown, said: ‘It’s like trying to put the genie back in the bottle.’
The team, which had its work published in the Chemical Engineering Journal, believes its technique is scalable and has viable commercial applications, especially in the environmental remediation and metal-recovery field

Vivek Kanissery
 robonaut2..

nasa's big leap..
they are now going to use robots in space mission so that they can
reduce the number of humans who face risks..they will be used in doing
maintenance works outside the space shuttle etc..

they are of the size of humans in space suits..

just have a look:http://www.nasa.gov/topics/technology/features/robonaut.html
Mithun MathewSixth Sense


'SixthSense' is a wearable gestural interface that augments the
physical world around us with digital information and lets us use
natural hand gestures to interact with that information.
The SixthSense prototype is comprised of a pocket projector, a mirror
and a camera. The hardware components are coupled in a pendant like
mobile wearable device. Both the projector and the camera are
connected to the mobile computing device in the user’s pocket. The
projector projects visual information enabling surfaces, walls and
physical objects around us to be used as interfaces; while the camera
recognizes and tracks user's hand gestures and physical objects using
computer-vision based techniques. The software program processes the
video stream data captured by the camera and tracks the locations of
the colored markers (visual tracking fiducials) at the tip of the
user’s fingers using simple computer-vision techniques. The movements
and arrangements of these fiducials are interpreted into gestures that
act as interaction instructions for the projected application
interfaces. The maximum number of tracked fingers is only constrained
by the number of unique fiducials, thus SixthSense also supports
multi-touch and multi-user interaction.


http://www.youtube.com/watch?v=nZ-VjUKAsao
  
athira
 
TATTOO
Scientists and engineers in china, Singapore, and the United States have developed a temporary tattoo like electronic device capable of sensing electrical signals such as brain waves and muscle activity and then transmitting data. To make the epidermal electronics, they used techniques pioneered at the University of Illinois, Urbana- Champaign, that allow the printing of inorganic semiconductors and metal interconnects on stretchable surfaces. The patch sticks to the skin for up to 24 hrs, even without glue, and it draw all its power from mix of induction and small embedded solar cells.
 

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