Tuesday, March 12, 2013

WLAN-Wireless LAN



ABSTRACT of WLAN-Wireless LAN

The term “Computer Network” to mean a collection of autonomous computers interconnected by a single technology .By this interconnection they are able to exchange information. Local Area Networks are privately owned networks within a single building or campus of few kilometers in size. In a traditional LAN we are connecting computers to the network through cables. But the wireless local area network (WLAN) is a flexible data communications system that can use either infrared or radio frequency technology to transmit and receive information over the air. Here each computer has a radio Modem and Antenna with which it can communicate with other systems. One important advantage of WLAN is the simplicity of its installation. Installing a wireless LAN system is easy and can eliminate the needs to pull cable through walls and ceilings. WLANs allow greater flexibility and portability than do traditional wired local area networks (LAN). 802.11 was implemented as the first WLAN standard. It is based on radio technology operating in the 2.4 GHz frequency and has a maximum throughput of 1 to 2 Mbps.

Hadoop


Computing in its purest form, has changed hands multiple times. First, from near the beginning mainframes were predicted to be the future of computing. Indeed mainframes and large scale machines were built and used, and in some circumstances are used similarly today. The trend, however, turned from bigger and more expensive, to smaller and more affordable commodity PCs and servers.
Most of our data is stored on local networks with servers that may be clustered and sharing storage. This approach has had time to be developed into stable architecture, and provide decent redundancy when deployed right. A newer emerging technology, cloud computing, has shown up demanding attention and quickly is changing the direction of the technology landscape. Whether it is Google’s unique and scalable Google File System, or Amazon’s robust Amazon S3 cloud storage model, it is clear that cloud computing has arrived with much to be gleaned from.
Cloud computing is a style of computing in which dynamically scalable and often virtualizes resources are provided as a service over the Internet. Users need not have knowledge of, expertise in, or control over the technology infrastructure in the “cloud” that supports them. 

Need for large data processing

We live in the data age. It’s not easy to measure the total volume of data stored electronically, but an IDC estimate put the size of the “digital universe” at 0.18 zettabytes in 2006, and is forecasting a tenfold growth by 2011 to 1.8 zettabytes.
Some of the large data processing needed areas include:-

• The New York Stock Exchange generates about one terabyte of new trade data per day.

• Facebook hosts approximately 10 billion photos, taking up one petabyte of storage.

• Ancestry.com, the genealogy site, stores around 2.5 petabytes of data.

• The Internet Archive stores around 2 petabytes of data, and is growing at a rate of 20 terabytes per month.

• The Large Hadron Collider near Geneva, Switzerland, will produce about 15 petabytes of data per year.

The problem is that while the storage capacities of hard drives have increased massively over the years, access speeds—the rate at which data can be read from drives have not kept up. One typical drive from 1990 could store 1370 MB of data and had a transfer speed of 4.4 MB/s,§ so we could read all the data from a full drive in around five minutes. Almost 20 years later one terabyte drives are the norm, but the transfer speed is around 100 MB/s, so it takes more than two and a half hours to read all the data off the disk. This is a long time to read all data on a single drive—and writing is even slower. The obvious way to reduce the time is to read from multiple disks at once. Imagine if we had 100 drives, each holding one hundredth of the data. Working in parallel, we could read the data in under two minutes.This shows the significance of distributed computing.

Embedded Zero Tree – Algorithm for Image Coding


Embedded Zero Tree – Algorithm for Image Coding



In the present digital world, we manage and store different types of data like video,music,images, text files etc digitally in our computers which basically are digital systems. In the case of storing any media type we always look forward to minimum size and maximum quality. When we consider the case of storing an image, we always adopt a “compress and store” algorithm, in which the image is first compressed to reduce the space occupied by the image using compression algorithms and then the data is written into the memory for storage. There are already many algorithms available for image compression and storing and they are being used based on the application and importance of the data. Embedded Zero tree Wavelet (EZW) algorithm is an efficient compression algorithm which is comparatively a newcomer in the field of image coding.

INTRODUCTION
EZW algorithm is a lossy compression algorithm in which bits are generated in a bit stream, according to their importance. The EZW encoder calculates a best suited threshold value for compress the still image at a specific decomposition level, followed by multilevel decomposition steps using this threshold. Normally the threshold ranges from 6 to 60, for a decomposition level of 8

Embedded Zero tree Wavelet Algorithm
Fig: Example for a three level wavelet decomposed image

Sunday, March 10, 2013

3D Technology

Introduction of 3D Television


Three-dimensional TV 3D Television is expected to be the next revolution in the TV history. They implemented a 3D TV prototype system with real-time acquisition transmission, & 3D display of dynamic scenes. They developed a distributed scalable architecture to manage the high computation & bandwidth demands. 3D display shows high-resolution stereoscopic colour images for multiple viewpoints without special glasses. This is first real time end-to-end 3D TV system with enough views & resolution to provide a truly immersive 3D experience.Japan plans to make this futuristic television a commercial reality by 2020as part of abroad national project that will bring together researchers from the government, technology companies and academia. The targeted "virtual reality" television would allow people to view high definitionimages in 3D from any angle, in addition to being able to touch and smell the objects being projected upwards from a screen to the floor.
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