Engineers Develop One-Way Transmission System for Sound Waves

While many hotel rooms, recording studios, and even some homes are built with materials to help absorb or reflect sound, mechanisms to truly control the direction of sound waves are still in their infancy. However, researchers at the California Institute of Technology (Caltech) have now created the first tunable acoustic diode-a device that allows acoustic information to travel only in one direction, at controllable frequencies.The mechanism they developed is outlined in a paper published on July 24 in the journal Nature Materials.
 Borrowing a concept from electronics, the acoustic diode is a component that allows a current -- in this case a sound wave -- to pass in one direction, while blocking the current in the opposite direction. "We exploited a physical mechanism that causes a sharp transition between transmitting and nontransmitting states of the diode," says Chiara Daraio, professor of aeronautics and applied physics at Caltech and lead author on the study. "Using experiments, simulations, and analytical predictions, we demonstrated the one-way transmission of sound in an audible frequency range for the first time."
 This new mechanism brings the idea of true soundproofing closer to reality. Imagine two rooms labeled room A and room B. This new technology, Daraio explains, would enable someone in room A to hear sound coming from room B; however, it would block the same sound in room A from being heard in room B.
 "The concept of the one-way transmission of sound could be quite important in architectural acoustics, or the science and engineering of sound control within buildings," says Georgios Theocharis, a postdoctoral scholar in Daraio's laboratory and a co-author of the study.
 The system is based on a simple assembly of elastic spheres -- granular crystals that transmit the sound vibrations -- that could be easily used in multiple settings, can be tuned easily, and can potentially be scaled to operate within a wide range of frequencies, meaning its application could reach far beyond soundproofing.
 Similar systems have been demonstrated by other scientists, but they all feature smooth transitions between transmitting and nontransmitting states instead of the sharp transitions needed to be more effective at controlling the flow of sound waves. To obtain the sharp transition, the team created a periodic system with a small defect that supports this kind of quick change from an "on" to an "off" transmission state. According to Daraio, this means the system is very sensitive to small variations of operational conditions, like pressure and movement, making it useful in the development of ultrasensitive acoustic sensors to detect sound waves. The system can also operate at different frequencies of sound and is capable of downshifting, or reducing the frequency of the traveling signals, as needed.
 "We propose to use these effects to improve energy-harvesting technologies," she says. "For example, we may be able to scavenge sound energy from undesired structural vibrations in machinery by controlling the flow of sound waves away from the machinery and into a transducer. The transducer would then convert the sound waves into electricity." Daraio says the technology can also shift the undesired frequencies to a range that enables a more efficient conversion to electricity.The team plans to continue studying the fundamental properties of these systems, focusing on their potential application to energy-harvesting systems. They also believe that these systems may be applicable to a range of technologies including biomedical ultrasound devices, advanced noise control, and even thermal materials aimed at temperature control.
 "Because the concepts governing wave propagation are universal to many systems, we envision that the use of this novel way to control energy might enable the design of many advanced thermal and acoustic materials and devices," says Daraio.
 The research was supported by the National Science Foundation, the Office of Naval Research, and the A. S. Onassis Benefit Foundation.

Data Travelling by light

Regular LEDs can be turned into optical WLAN with only a few additional components thanks to visible light communication (in short, VLC). The lights are then not just lighting up, they also transfer data. They send films in HD quality to your iPhone or laptop, with no loss in quality, quickly and safely.Just imagine the following scenario: four people are comfortably ensconced in a room. Each one of them can watch a film from the Internet on his or her laptop, in HD quality. This is made possible thanks to optical WLAN. Light from the LEDs in the overhead lights serves as the transfer medium. For a long time, this was just a vision for the future. However, since scientists from the Fraunhofer Institute for Telecommunications, Heinrich Hertz Institute HHI in Berlin, Germany, have developed a new transfer technology for video data within the scope of the OMEGA project of the EU, its implementation in real life is getting markedly closer.

At the end of May, the scientists were able to present the results of the project in Rennes, France. They were able to transfer data at a rate of 100 megabits per second (Mbit/s) without any losses, using LEDs in the ceiling that light up more than ten square meters (90 square feet). The receiver can be placed anywhere within this radius, which is currently the maximum range. "This means that we transferred four videos in HD quality to four different laptops at the same time," says Dr. Anagnostis Paraskevopoulos from the HHI.

"The fundamentals of visible light communication (VLC) were developed together with the industry partners Siemens and France Telecom Orange Labs," said the expert. At HHI, the team of project manager Klaus-Dieter Langer is now further developing the new technology. "For VLC the sources of light -- in this case, white-light LEDs -- provide lighting for the room at the same time they transfer information. With the aid of a special component, the modulator, we turn the LEDs off and on in very rapid succession and transfer the information as ones and zeros. The modulation of the light is imperceptible to the human eye. A simple photo diode on the laptop acts as a receiver.

As Klaus-Dieter Langer explains, "The diode catches the light, electronics decode the information and translate it into electrical impulses, meaning the language of the computer." One advantage is that it takes only a few components to prepare the LEDs so that they function as transfer media. One disadvantage is that as soon as something gets between the light and the photo diode (for example, when someone holds his hand over the diode) the transfer is impaired. Laptops, Palm devices or mobile telephones are all potential end devices.The scientists emphasize that VLC is not intended to replace regular WLAN, PowerLAN or UMTS. It is best suited as an additional option for data transfer where radio transmission networks are not desired or not possible -- without needing new cables or equipment in the house. Combinations are also possible, such as optical WLAN in one direction and PowerLAN for the return channel. Films can be transferred to the PC like this and also played there, or they can be sent on to another computer.The new transmission technology is suitable for hospitals, for example, because radio transmissions are not allowed there. Despite this fact, high data rates must be transmitted without losses and unzipped, according to the experts. If part of the communication occurs via the light in the surgical room, this would make it possible to control wireless surgical robots or transmit x-ray images. In airplanes, each passenger could view his own entertainment program on a display, saving aircraft manufacturers miles of cables. Another possible venue for the application of this technology are production facilities, where radio transmissions very often interfere with the processes.

Ideal diet before and after workout

 What you eat before and after a workout is as important as theregimen itself...An effective workout depends on many factors - the mostimportant one being your diet. What you eat before a workout prepares your body for the stress and the meal after that isresponsible for muscle building and body repair. Here's whatyou must keep in mind so as to tailor your meals and maximizeyour workout.

PRE WORKOUT:
Get the carbs Give your body a dose of carbohydrates one hour before youhit the gym. Eat a fruit (apple would be ideal). You may alsohave toast, cornflakes or idlis. You could also just eat a bananafor the complex carbohydrates it provides. These foods need comparatively little time to digest, are easy on the body and provide you with maximum energy during the workout. Also,ensure that you drink a glass of water before the workout, so that your body is well hydrated.
 Never go hungry
Do not hit the gym on an empty stomach. The stress that exercise has on the body, combined with the lack of sugar (energy) will lead to hypoglycemia, a condition that will make you prone to fatigue.
After a heavy meal
For a diabetic, it is very important to workout soon after aheavy meal. However, normal individuals must maintain a gap of two to three hours between a heavy meal and the workout. The logic is to allow the sugar level in the body to reach an optimum level.
POST WORKOUT:
Use the window
During a workout, the level of cortisol (also known as the  destructive hormone) in the body increases, thereby making it prone to infections. That's precisely why the hour just after a workout is known as the 'window period', as it allows for infections to enter the body. Use this opportunity and eat as soon as possible.
Get a drink
The body loses salt due to sweating. That is why it's very important to compensate via a rich source of electrolyte such as ORT.
Have proteins, but...
Do not rely completely on proteins for your supply of energy, as they are far more difficult to digest and take a toll on your kidneys. To aid digestion, make sure you include lots of greens

in your meal, as they are rich in fibre.
Create supplements
The body needs a high-protein diet for muscle building. However, relying on supplements is not the answer. The best option for a post workout DIY supplement is to take the watery part of curd (that is very rich in proteins), chop a banana and apple into it and put it in the blender. It's a perfect combination of proteins and carbohydrates. Not to forget, the apple is rich in fibre

FRIENDSHIP DAY SONG DEDICATED TO ALL FRIENDS

I still hear your voice. I still miss your hands.
Today again I live withing your traces.
I still see you. I still feel your warmth.
Today again I live within the time spent with you.
In some stranger who passes by.
In leaves that fall and dance in the wind.
In the evening wind that touches my cheek.
You are in everything I see, hear and feel.
How about you ? How about you ?
Do you feel the same way ? How about you ?
I still feel you.
Like this, even at the moment when I'm singing this song.

 HAPPY FRIENDSHIP DAY TO ALL MY FRIENDS LOVE U A LOT

OUR FINAL PRESENTATION ON INDIAN AND JAPANESE CULTURE

Hey it's me shah again with final presentation of our INDIA and JAPANESE culture which we made during a training so i felt u should also check it and give ur suggestions whether some sectors should be improve or not
so if u want to download or preview click here and just want to preview wait for some time it will open in ur browser itself and one more thing please don't forget to do comment on it.THANKS

Nanotechnology pushes battery life to eternity

                         
In a crucial step towards the development of self-powering portable
electronics,researchers at RMIT University in Melbourne have for the
first time characterised the ability of piezoelectric thin films to turn
mechanical pressure into electricity.
The pioneering result is published in the 21 June Issue of the leading
materials
science journal, Advanced Functional Materials.
Lead co-author Dr Madhu Bhaskaran said the research combined the
potential of
piezoelectrics - materials capable of converting pressure into electrical
energy - and the cornerstone of microchip manufacturing, thin film
technology."The power of piezoelectrics could be integrated into running
shoes to charge mobile phones, enable laptops to be powered through
typing or even used to convertblood pressure into a power source for
pacemakers - essentially creating aneverlasting battery," she said.
"The concept of energy harvesting using piezoelectric nanomaterials has
been demonstrated but the realisation of these structures can be complex
and they are poorly suited to mass fabrication.
"Our study focused on thin film coatings because we believe they hold the
onlypractical possibility of integrating piezoelectrics into existing electronic
technology." The Australian Research Council-funded study assessed the
energy generation capabilities of piezoelectric thin films at the nanoscale,
for the first time precisely measuring the level of electrical voltage and
current - and therefore, power - that could be generated.Dr Bhaskaran
co-authored the study with Dr Sharath Sriram, within RMIT's
MicroplatformsResearch Group, led by Professor Arnan Mitchell.
The pair collaborated with Australian National University's Dr Simon Ruffell
on the research. "With the drive for alternative energy solutions, we
need to find more efficient ways to power microchips, which are the
building blocks of everyday technology like the smarter phone or faster
computer," Dr Bhaskaran said. "The next key challenge will be amplifying
the electrical energy generated by the piezoelectric materials to enable them
to be integrated into low-cost,compact structures."

A DAY WITH A GIRL

i could remember a day when i was with my x girl a lady beggar came and asked me for some penny i nod had chillar but i gave her 5 rs so she was very happy and blessed us that we will be together for long time but after few month she went away even she refused to recognize me i asked her which kind of relation ship we had or have but i got a reply nothing and today i was thinking while a beggar came that he/she also give such kind of blessing then i m gonna die so without giving any response i moved away from that place.