How Does SONAR Works ?

What Is Sonar?

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  Sound navigation and ranging, or sonar, is an umbrella term for technology and methods that use sound to detect objects, usually underwater, much the same way bats rely on sound for catching food in the air. The basic principles on which sonar relies are that sound moves at a steady rate through a given medium, such as air or water, and that certain types of objects produce certain types of sounds. With this knowledge, calculations can determine the distance to an object and identify it with reasonable certainty. The Navy mainly uses sonar to detect vessels, torpedoes and mines. Commercial applications for sonar include navigation, mapping and locating fish.

Passive Sonar

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  Passive sonar, as the name implies, simply involves listening. Marine biologists use passive sonar techniques to locate and study life in the oceans, using the sounds particular to an animal to help identify it. Similarly, ships and submarines use passive sonar to locate ships and subs and other threats. Because certain types of engines vibrate at certain frequencies, they can be identified through passive sonar. A metal object such as a wrench, dropped in a sub, may be detectable by passive sonar miles away. Frequently, a vessel will tow a passive sonar array behind it to listen with minimal interference from its own noises.

Active Sonar

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  Active sonar involves both the transmission and receiving of sound waves. An active sonar system sends a sound pulse and measures the length of time for the sound to be reflected back. Because the speed at which the sounds moves is very fast and remains constant, the distance to the object can be calculated quickly. Active sonar can use a concentrated pulse of sound in a specific direction, so information about an object's direction can also be obtained through some active sonar applications. Active sonar can be deployed by helicopters, mounted in buoys or on boats, or hand-held.

Negative Effects of Sonar

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  One major criticism of active sonar is its effect on marine mammals, such as dolphins and whales, who also use natural sonar for their navigation. Testing of very low frequency active sonar by the U.S. Navy, because it causes damage to an animal's ability to detect sound, has been implicated in the beaching of whales. In other cases, it has been suggested that Navy sonar tests have caused whales to surface too quickly, inducing painful and often fatal decompression sickness. The U.S. Navy accepted responsibility for the deaths of seven beached whales in the Bahamas in 2000 that were found with acoustically induced hemorrhages around the ears and eyes after a test of low-frequency sonar in the area.

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Windows 8 or RT

Microsoft bet the farm on the October 26, 2012, release of Windows 8, the most recent iteration of the company's operating system -- so much so that Microsoft CEO Steve Ballmer told The Seattle Times that "Windows 95 was certainly the biggest thing in the last 20 years until now ... I think Windows 8 certainly surpasses it." The tech giant's 2012 strategy isn't simply to release a new version of Windows, however. In addition to the radical redesign of the operating system, the October rollout includes a new version of its Windows Phone and a special version of Windows called "Windows RT."                                                                               Significance of Windows RT                             Windows RT is an operating designed specifically to run on low-power processors common in tablets. It shares code in common with Windows 8 but the user interface differs because of their different expected purposes. Windows RT tablets can do less than Windows 8 tablets, but they're cheaper and have longer battery life. Windows RT and Windows 8 are the first versions of Windows that can run on a tablet computer. Most tablets use a low-power type of processor known as an ARM processor -- and you can't install Windows 7 on a tablet with an ARM processor. Now Windows can get onto ARM processors and, thereby, make a solid entry into the tablet market.

Processor Architecture

• Each computer operating system is built around a central set of code called a "kernel" that translates the stuff that happens in programs into something that the hardware can process. Kernels are optimized to work with a very specific hardware standard used in the central processing chip. Until Windows 8, the Windows kernel worked exclusively with the "x86" standard from Intel. A computer processor that can handle x86 instructions (including offerings from Intel and AMD) can run Windows 7. Conversely, a computer whose processor can't interpret x86 can't run Windows 7. That's why, for example, you can't run Windows natively on old, pre-Intel Apple computers.

Windows RT and ARM

• The ARM processor was designed to optimize power consumption. It runs at lower power with less memory and uses different hardware and hardware instructions than x86 machines, so the full power of Windows 8 on the PC -- optimized for the x86 processor -- is too much for an ARM chip. Windows 8 includes a full feature set that works with a wide range of desktop and laptop computers. Windows RT, by contrast, works with tablets and so-called embedded systems that emphasize low power, continuous operation, frequent hibernation and fewer devices (like hard drives or printers) to manage.

Windows 8 vs. Windows RT

• Because of the differences in processor technology, the wide range of programs that work in Windows 8 won't all work in Windows RT. Windows 8 can handle large, memory- and processor-heavy programs like Adobe Photoshop that would overtax the ARM processor. Although Windows 8 and Windows RT will look alike -- they both feature the Windows 8 style of start screen with colorful tiles -- the most obvious difference to the end user will be application choice. Windows 8 has a full-featured desktop mode, just like Windows 7, that can run apps designed for any version of Windows. Windows RT, however, can only run the apps that, during development, Microsoft called "Metro-style." These apps run from the Start screen and are optimized for touch and for fast task switching, just like the apps on an iPad or an Android tablet. Windows RT will include a desktop mode. However, only a few applications straight from Microsoft, like Paint and Notepad, will run from the RT desktop.

Windows RT Tablets

• Microsoft's move to Windows RT -- called "Windows on ARM," or WOA, early in the development cycle -- stems from the growth of the tablet computer market that runs on low-power processors. The Apple iPad currently dominates the market with nearly a two-thirds share, and Android tablets come in second place. For Windows to thrive as an ecosystem that links Microsoft-provided services across computers, tablets and smartphones, the operating system needs a foothold in the tablet space. That's what Windows RT aims to achieve. A Windows RT device will be functionally identical to an iPad, an Android tablet or the ill-fated HP TouchPad.

Two Tablets

• Consumers should be careful, however. Microsoft and its partners have optimized Windows 8 and its hardware to the point that full-powered Windows 8 tablets, with full desktop support, will hit the market the same time as Windows RT tablets. Both types will be branded similarly, so it's up to the buyer to understand the difference between a Windows 8 tablet and a Windows RT tablet and make a purchasing decision knowing the very real differences between the two forms of Windows. The Windows RT tablets can run the same "Metro style" apps that run on Windows 8 and apps available from Microsoft's online app store, but that's all they can run. Because they have limited processing power they can't run full-powered desktop apps -- or anything that was built for Windows 7. In return, though, consumers get significantly lower prices and better battery life.

Value Proposition

• A Windows RT tablet provides superior battery life and light weight at a price similar to that of other ARM-based tablets. Analysts expect that Windows RT tablets will cost between $300 and $700; Windows 8 tablets will probably ring up to $500 to $900 or more. If a tablet with a long battery life and lower price makes more sense than a more expensive tablet that can run Windows 7 apps too, then Windows RT might be a sensible choice -- especially for consumers who only use their tablets for email, Web browsing and games. Higher-priced Windows 8 tablets -- or even laptops -- make more sense if you need to run Windows 7 programs.

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How the Touch Screen Works

Today,the increase in craze towards Screen Touch Mobiles and Tablets lets you to buy and Android or IPhone. But Ever you imagined that What happens inside the Screen when you touch your preference .
Let us see it in this Post :-

Older technology

In older times the touch screen used a thin layer of flexible polyster film attached over a coat of glass or plastic. Other coatingssuch as criss-crossed or indistinguishable wires are also used in place of it.

Now when top layer is pressed over the lower layer with the help of a finger or its stylus, these invisible wires get intersect with each other thus will interrupt the flow current resulting change in directoion which helps the device in deciding where is the touch located on screen. Here, a minimum amount of touch needs to applied to observe the result

In such older kind of touch screen technology, the sensitivity gets decreasing towards the edges due to out-dated technology but nowadays capacitivetouchscreens are available which uses its smart technology so that the sensitivity of the touch screen remains constant & uniform throught the screen.

Newer Technology

In this technology, a capacitive film is place over the main screen, holds current which is purposely flown for this technology. Now when this film is touched by finger or stylus, this reduces the amount of current flowing at the contact point of screen.

Now as we know that there is nothing like invisible wires pressed hence, due to the capacitive screen can locate the contact point sensitively such that it is uniform throught the screen with a slightest touch.

Signals travel from the touch screen to the processor as electrical impulses.

The processor uses software to analyze the data and determine the features of each touch. This includes size, shape and location of the affected area on the screen. If necessary, the processor arranges touches with similar features into groups. If you move your finger, the processor calculates the difference between the starting point and ending point of your touch.

The processor uses its gesture-interpretation software to determine which gesture you made. It combines your physical movement with information about which application you were using and what the application was doing when you touched the screen.

The processor relays your instructions to the program in use. If necessary, it also sends commands to the iPhone's screen and other hardware. If the raw data doesn't match any applicable gestures or commands, the iPhone disregards it as an extraneous touch.

All these steps happen in an instant -- you see changes in the screen based on your input almost instantly. This process allows you to access and use all of the iPhone's applications with your fingers.

The shape of the screen changes when you need it to as well -- you can shift the perspective from vertical to horizontal by tilting the phone. An accelerometer inside the iPhone lets the operating system know to change the orientation of the image on the screen. This means that you can scroll through long lists of music files on a long, narrow screen, and you can watch movies in a widescreen format.

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How ATMs Work?

INTRO

Yo­u're short on cash, so you walk over to the automated teller machine (ATM), insert your card into the card reader, respond to the prompts on the screen, and within a minute you walk away with your money and a receipt. These machines can now be found at most supermarkets, convenience stores and travel centers. Have you ever wondered about the process that makes your bank funds available to you at an ATM on the other side of the country?

How Do ATMs Work?

An ATM is simply a data terminalwith two input and four output devices. Like any other data terminal, the ATM has to connect to, and communicate through, a host processor. The host processor is analogous to an Internet service provider (ISP) in that it is the gateway through which all the various ATM networks become available to the cardholder (the person wanting the cash).

Most host processors can support either leased-line or dial-up machines. Leased-line machines connect directly to the host processor through a four-wire, point-to-point, dedicated telephone line. Dial-up ATMs connect to the host processor through a normal phone line using a modem and a toll-free number, or through an Internet service provider using a local access number dialed by modem.

Leased-line ATMs are preferred for very high-volume locations because of their thru-put capability, and dial-up ATMs are preferred for retail merchant locations where cost is a greater factor than thru-put. The initial cost for a dial-up machine is less than half that for a leased-line machine. The monthly operating costs for dial-up are only a fraction of the costs for leased-line.

The host processor may be owned by a bank or financial institution, or it may be owned by an independent service provider. Bank-owned processors normally support only bank-owned machines, whereas the independent processors support merchant-owned machines.

Parts of the Machine

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How Websites Work?

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RETINA DISPLAY

Retina Display is a brand name used by Apple for liquid crystal displays which they claim to have a high enough pixel density that the human eye is unable to notice pixelation at a typical viewing distance. The term is used for several Apple products, including the iPhone, iPod Touch, iPad, and MacBook Pro.As the typical viewing distance would be different depending on each device's usage, the pixels per inch claimed as retina quality can be different for the smallest devices (326, iPhone and iPod Touch): greater than the mid-sized devices (264, iPad) and greater than the larger devices (220, MacBook Pro).

The displays are manufactured by different suppliers. Currently, the iPad's display comes from the same suppliers Samsung use whilst the suppliers of LG make the MacBook Pro display,along with the iPhone and iPod Touch displays.Apple has applied to register the term "Retina" as a trademark in regard to computers and mobile devices with the United States Patent and Trademark Office, Canadian Intellectual Property Office, and in Jamaica.
DIFFERENCES IN PREVIOUS DISPLAYS 'N' RETINA DISPLAY

Apple markets the following devices as having retina displays.(FROM WIKIPEDIA)

Model	PPI (pixels per inch)	ppcm (pixels per cm)	Resolution	Typical Viewing Distance (in/cm)	Single Pixel Visual angle(arcminutes)
iPhone 4/4S and iPod Touch(4th generation)	326	128	960×640	10 inches (25 cm)	1.1
iPhone 5 and iPod Touch (5th generation)			1136×640
iPad (3rd generation)	264	104	2048×1536	15 inches (38 cm)	0.87
MacBook Pro (3rd generation)	220	87	2880×1800	20 inches (51 cm)	0.78

VIDEO

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