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Monday, August 21, 2006

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Tuesday, July 25, 2006

30-year weather forecast by Japan

Japan's science ministry hopes to harness the power of a supercomputer called the Earth Simulator to deliver forecasts 30 years into the future.
The computer, which occupies a warehouse in Yokohama, is one of the most powerful in the world. Scientists will use it to analyse long-term trends using data such as atmospheric pressure, global air and sea temperatures, crust movements and currents.
The forecasts will tell which areas are likely to experience recurring disasters such as typhoons, storms, heavy snow, coastal erosion and droughts. The government may be able to divert money and resources into those areas in advance, either to take counteractive prevention measures or to ensure rapid response.
Farmers may also be able to plan crop planting based on the changing environment.
Japan's vulnerability to the weather was underlined yesterday as 21 people in central and western Japan were reported missing or killed by torrential rains that swept away houses and destroyed roads. Flooding and mudslides are common in the summer months, as typhoons bring intense rain.
The Earth Simulator was launched in 2002 but until now it has been used to predict weather in the short-term. Until 2004, when surpassed by IBM's Blue Gene, it was the world's fastest computer, able to undertake 35 trillion calculations per second.
The ministry is intending to launch the new project by spring next year, investing in the region of £10 to £15 million a year.
Now the ministry is working on refining the simulation models, which are crucial to accurate projection.
The project is expected to cover the whole planet, producing forecasts for areas of the globe as small as two square miles.

Courtesy: http://www.telegraph.co.uk/connected/main.jhtml

Monday, July 24, 2006

Evolution of mobile phone

Early Years
Mobile rigs were the beginning of mobile phones, along with taxicab radios, two way radios in police cruisers, and the like. A large community of mobile radio users, known as the mobileers, popularized the technology that would eventually give way to the mobile phone. Originally, mobile phones were permanently installed in vehicles, but later versions such as the so-called "bag phones" were equipped with a cigarette lighter plug so that they could also be carried, and thus could be used as either mobile or as portable phones.
What was possibly the first real mobile phone, in the sense that it was connected to the telephone network, was tested by the Swedish police in 1946 for use in police cruisers. A half dozen calls could be made before the police car's battery ran out. Radiophones began to be publicly available in the US at the end of the 1940s[1], though the distinction between such phones and a two-way radio becomes blurry since special systems are required to "patch" into the phone network with the assistance of human operators. Recognizable mobile phones with direct dialing have existed at least since the 1950s.
For a discussion of the history of the Mobile Radio Service (MRS), and Improved Mobile Radio Service (IMRS) prior to the cellular mobile telephone AMPS in the US, see [2] Because of the long waiting time to be issued an MRS or IMRS radio telephone in the 1960's and 1970's, "autopatch" telephone conversations became popular among amateur radio operators with the advent of FM repeaters. Because of Federal Communications Commission rules concerning the Amateur Radio Service, business conversations were prohibited from such calls.
One of the first truly successful public commercial mobile phone networks was the ARP network in Finland, launched in 1971. Posthumously, ARP is sometimes viewed as a zeroth generation (0G) cellular network, being slightly above previous proprietary and limited coverage networks.

First Generation Cellular
The first hand held mobile phone to become commercially available was the Motorola DynaTAC 8000X, which received approval in 1983. Mobile phones began to proliferate through the 1980s with the introduction of "cellular" phones based on cellular networks with multiple base stations located relatively close to each other, and protocols for the automated "handover" between two cells when a phone moved from one cell to the other. At this time analog transmission was in use in all systems. Mobile phones were somewhat larger than current ones, and at first, all were designed for permanent installation in cars (hence the term car phone). In Switzerland, the name for the big car-based phone models was "Nationales Autotelefon", and the abbreviation of it ("Natel") persists as the common designation for mobile phones. Soon, some of these bulky units were converted for use as "transportable" phones the size of a briefcase. Motorola introduced the first truly portable, hand held phone. These systems (NMT, AMPS, TACS, RTMI, C-Netz, and Radiocom 2000) later became known as first generation (1G) mobile phones.
In September 1981 the first cell phone network with automatic roaming was started in Saudi Arabia; it was an NMT system manufactured by Svenska Radio Aktiebolaget (SRA). One month later the Nordic countries started an NMT network with automatic roaming between countries.
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Second Generation Cellular
In the 1990s, second generation (2G) mobile phone systems such as GSM, IS-136 ("TDMA"), iDEN and IS-95 ("CDMA") began to be introduced. The first digital cellular phone call was made in the United States in 1990, in 1991 the first GSM network opened in Europe. 2G phone systems were characterised by digital circuit switched transmission and the introduction of advanced and fast phone to network signalling. In general the frequencies used by 2G systems in Europe were higher though with some overlap, for example the 900 MHz frequency range was used for both 1G and 2G systems in Europe and so such 1G systems were rapidly closed down to make space for 2G systems. In America the IS-54 standard was deployed in the same band as AMPS and displaced some of the existing analog channels.
Coinciding with the introduction of 2G systems was a trend away from the larger "brick" phones toward tiny 100–200g hand-held devices, which soon became the norm. This change was possible through technological improvements such as more advanced batteries and more energy-efficient electronics, but also was largely related to the higher density of cellular sites caused by increasing usage levels.
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Third Generation Cellular
Not long after the introduction of 2G networks, projects began to develop 3G systems. Inevitably there were many different standards with different contenders pushing their own technologies. Quite differently from 2G systems, however, the meaning of 3G has been standardized in the IMT-2000 standardization process. This process did not standardize on a technology, but rather on a set of requirements (2 Mbit/s maximum data rate indoors, 384 kbit/s outdoors, for example). At that point, the vision of a single unified worldwide standard broke down and several different standards have been introduced.
During the development of 3G systems, 2.5G systems such as CDMA2000 1x and GPRS were developed as extensions to existing 2G networks. These provide some of the features of 3G without fulfilling the promised high data rates or full range of multimedia services. For example, CDMA2000-1X delivers theoretical maximum data speeds of up to 307 kbit/s. Just beyond these is the EDGE system which in theory covers the requirements for a 3G system, but is so narrowly above these that any practical system would be sure to fall short.
At the beginning of the 21st century, 3G mobile phone systems such as UMTS and CDMA2000 1xEV-DO have now begun to be publicly available. The final success of these systems is still to be determined.
Live streaming of radio and television [4] to 3G handsets is one future direction for the industry, with companies from RealPlayer [5] and Disney [6] recently announcing services.

With Courtesy: http://en.wikipedia.org/wiki/History_of_mobile_phones