Metal Detectors

Introduction:
Metal Detectors are basically used to find out objects that are metallic. Apart from this basic use of metal detectors they are also helpful in detecting land mines,weapons and other similar jobs.

How metal detectors work?
Metal detectors are manufactured using various smaller devices,one of which is an oscillator that produces A.C. current which when passes through a coil generates an alternating magenetic field.
One of the coils is used to measure the magnetic field.Due to the presence of magnetic substance,the variation in the magnetic field can be used as an approach to measure it.
The microprocessors present in the metal detectors figure out the type of the metal present.Metal detectors work on the principle of electromagnetism.

History:
During the 19th century,scientists were trying to invent such a device that can be used to detect metallic presence.Various devices that were initially developed had a very limit scope and they required a lot of energy to perform this task,so they were not very successful.
In 1937, Gerhard Fisher developed a system keeping the concept limited to radio direction-finding for accurate navigation.This invention was very successful and hence he instantly got its rights patent.

Scope of metal detectors:
They can be used to detect metals even inside sand,mud,wood.They are very handy for the purpose of archeology,security screening,treasure hunting and various similar tasks.

Digital Camera

Introduction:
Talking about Digital Camera,everyone is aware what is the role/function of a digital camera,and for those who are not sure about it,here is a short description.A digital camera captures the moving films or even capture the still photographs.

Difference between various cameras:
Many compact digital cameras have the functionality to capture moving videos,sound and still images.A digital camera can perform various other functions which a routine film camera may fail to do,for example they can display the pictures on the screen instantly.A small memory device can store  thousands of images which can be deleted any moment as and when required.

Types of digital cameras:
There are various types of digital cameras availablt in the market some of them being compact digital camera,bridge camera,digital single lens reflex camera,digital range finders,life scan camera system.Among the above mentioned cameras,most use CCD(Charge Coupled Device).

Technology Used:
Talking in terms of technology,a digital camera can be defined captures video and still photographs in a digital format.These record the photographs based on the sensers that work according to the light available.To record videos,digital cameras do not require any reel,instead they use memory chip for recording purpose.It records data in the form of audio/video format files or images,This data can then directly be sent to the computer system and then can be printed/sent to other devices as and when required.Some latest cameras even have the bluetooth functionality to send and recieve files directly.

Advantages of digital cameras:

• The biggest advantage of a digital camera is the reusability of the memory device used to store images/videos.The data already present in the memory chip can be transferred to the computer system any time,there is no need to wait for the memory to get full before transfer and then after the transfer is complete,the same chip can be used again several times,unlike normal camera films which are made for one time use.
• Digital cameras possess high quality lens for better quality picture.
• They also have the zoom function to focus on the object.
• Along with the above mentioned features it also has the night mode apart from flash which provides better quality image even when used in dark places.
  

Inferno Operating System

Definition:
Inferno is a project by Lucent Technologies to create a system - independent operating system. The aims of Inferno include a common looking interface between hardware, a platform independent set of API’s, and a programming language that will work no matter where you take it.

Some Facts about Inferno:

• Inferno is the successor of Bell Lab’s Plan 9 operating system. These devices go from the set-top Network Computers to the Sony Play Station, to the ordinary computer.
• The core of Inferno is portability. Almost all of the operating system is based on Limbo, the programming language of Inferno. When porting Inferno from one hardware to another all one has to do is to modify the few hardware dependent functions, and then immediately the entire system will work on the new system.
• Many people see Inferno as a competitor to Java. Java in itself is a programming language that has many of the same functions as Limbo. Both are hardware independent and both are designed as large scale projects. But Inferno as a whole is an operating system, which in turns runs Limbo programs.
• There are plans in Lucent for the next version to let Java programs execute natively. This would mean that Java programs would be able to run on a system running Inferno as their operating system.
  

Design Principle:
Inferno is a distributed operating system based on two basic principles:

• Resources as files: all resources are represented as files within a hierarchical file system.
• Standard communication protocol: a standard protocol, called Styx (9p2000), is used to access all resources, both local and remote
  

LIMBO, the programming language:
Limbo is the application programming language for the Inferno operating system. Although Limbo looks syntactically like C, it has a number of features that make it easier to use, safer, and more suited.

A C-like language that compile to byte codes and that run

• Over the VM (30/40 times slower than C)
  

• JIT compilation (2/3 times slower than C)
  

Pascal-like type declaration
x: int;

C-like assignments
x := 42;

Constants
EOF: con –1;

Strings are not \0 terminated

Array slices
y := x[1;3];

Lists, tuples

Abstract data types can contain functions

A ref keyword to build reference out of values


Styx Protocol:
Styx makes use of the Inferno Namespace and file system to represent resource on the network in the form of file system.

The application can then transparently use this resource as a file, do open/read/write/close operations on it without knowing where the resource actually exists.

Styx is a high level protocol that can run over TCP/IP, UDP, ATM, PPP, etc.

Features of Inferno:

• Portability and Scalability
  

               The most important feature of Inferno is its portability across platforms and environments. It supports many popular processor architectures, and it is easily portable to new architectures.

• In addition to supporting different processor architectures, it also is portable in other aspects; it can run as a stand-alone operating system, and it can also run as a user application under various existing operating systems
  

SECURITY:
Inferno provides security of communication, resource control, and system integrity.

Inferno is secure against erroneous or malicious applications, and encourages safe collaboration between mutually suspicious service providers and clients.

Object modules may be signed by trusted authorities who guarantee their validity and behavior, and these signatures may be checked by the system the modules are accessed.

Conclusion:
Inferno supplies a rich environment for constructing distributed applications that are portable-in fact identical-even when running on widely divergent underlying hardware. Its unique advantage over other solutions is that it encompasses not only a virtual machine, but also a complete virtual operating system including network facilities.

Internet Protocol Television(IPTV)

Definition:
IPTV (Internet Protocol Television) describes a system where a digital television service is delivered using the Internet Protocol (IP) over a network infrastructure, which may include delivery by a broadband connection.
       Talking in general terms,IPTV is television content that, instead of being delivered through traditional broadcast and cable formats, is received by the viewer through the technologies used for computer networks.

History:
In 1994, ABC’s World News Now was the first television show to be broadcast over the Internet, using the CU-SeeMe videoconferencing software.
Internet radio company AudioNet started the first continuous live web-casts with content from WFAA-TV in January, 1998 and KCTU-LP on January 10, 1998.

Architecture:

• Broadcast IPTV has two major architecture forms:

          -free
          -fee based

• Free IPTV channels require only an Internet connection and an Internet enabled device such as a personal computer, HDTV connected to a computer or even a 3G cell/mobile phone to watch the IPTV broadcasts.
  

• IPTV uses a two-way digital broadcast signal sent through a switched telephone or cable network by way of a broadband connection and a set-top box programmed with software that can handle viewer requests to access to many available media sources.
  

Limitations:
Because IPTV requires real-time data transmission and uses the Internet Protocol, it is sensitive to packet loss and delays if the IPTV connection is not fast enough or picture break-up or loss if the streamed data is unreliable. This latter problem has proved particularly troublesome when attempting to stream IPTV across wireless links. Improvements in wireless technology are now starting to provide equipment to solve the problem.

Conclusion:
An IPTV offers you a advanced multi channel high definition TV (HDTV) as well as on demand entertainment. IPTV technology promises to give better and more contents available, Because of two way connection between viewer and service provider will know the views personal preferences and entertain them accordingly.

Central Processing Unit(C.P.U.)

Introduction:
CPU stands for Central Processing Unit which is a machine which implements computer programs.CPU is considered as the brain of the computer.It is that part of the computer that handles maximum number of computations.In large servers multiple processors are used whereas for home PCs or computers used for simple purpose even a singlr chip microprocessor is capable to handle the operations.CPU has two very important parts,one is the ALU(Arithmetic Logic Unit) & the other being CU(Control Unit).

Machine Code:
Machine code is the term used to define the laguage used by computers for their functioning.Most of the computer code is defined using the numbers '0' & '1'.Some professionals term this 'o' & '1' language as binary language.Since 1940 machine code has been the laguage for computers which is also referred as the assembly language.Every central processing unit has its own machine code and instruction set.When a programmer writes some code for some purpose and executes it,the compiled code in machine language is converted back in user understandable language and displayed accordingly.The machine code is stored in the form of an executable file unless the operating system instructs it to operate.When the code is scanned or executed then the system reads the arrangement and accordingly instructions are passed for appropriate operation.
The microprocessor reads these instructions in the form of '0' & '1' and the executable file contains the information about how many characters the microprocessor has to read in a single attempt.

MP4

Everyone in this computer age is aware of mp3 but hardly a few of them know about another upgrade of mp3 and that is mp4.It is the official filename extension for MPEG-4.

Technique:
The technique used in mp4 is not very different from that of mp3 but the fact that it is much more complex then mp3 cannot be ignored.To know more about mp4 initially the audio formatting has to be understood.For instance if alphabet 'D' has to be said seven times then in audio format it is written as 'D7'.This compresses the audio file to a great extent.As compared to audio file,compression of video file is more difficult and requires more effort.In this compression some specially programmed coding technique is used.Through compression & decompression pictures are transferred to the frequency domain.This is known as Kodak and the same is implemented in the conversion of files in mp4 format.

Advantage of using mp4:

• The biggest advantage of using mp4 technique is its storage capacity.For example a complete hindi movie requires more then 2 CDs for storage but if the same files are converted to mp4 format then more then four movies can be copied on a single CD.
  

Disadvantages of using mp4:

• Every technique has its advantages & disadvantages and this applies to mp4 as well.The invent of mp4 has increased the rate of piracy.
  
• It requires a lot of time to download files in mp4 format.
• And above all,files in mp4 format do not support smooth execution,they often face interrupted reading.

Difference between mp3 & mp4:

The compression method used in mp4 is similar to that of mp3 but the only difference is that mp4 format also supports video files.That is videos are considerably reduced in size when changed in mp4 and this is executed without much compromise with the quality of the content.

Memory Cards

Introduction:
Memory card is a solid state flash memory(type of memory which can be reprogrammed) data storage device which is used in many electronic devices such as mobile phones,digital cameras,music players and video games.In recent times,the usage of memory cards has shown a tremendous growth.

History of Memory cards:
The P.C. card launched in 1990 was the first memory card that came into existence.In current age,this P.C. card is used in commercial purposes.Some other memory cards were also launched during the same period among which compact flash,smart media and mini cards are the popular ones.Including these,there were some more that were very commonly used in the period from 1990 to 2000 such as memory stick,S.D. picture.The size of these cards continued to reduce throughout this period.In the electronic gadgets available in the market these days,place for memory cards is allotted at the time of manufacturing.Some of these devices even have place for more then one memory card.

Types of memory cards:

Micro SD Card:
This type of card is a flash removable memory card.Such cards are mainly used in mobile phones,portable media players,GPS devices etc.This is the smallest memory card in size among all present types.

Mini SD Card:
This card is a form factor(conversion of energy from one object to another object) removable and portable memory device.It is used in mobile phones,MP3 players,digital cameras and other similar gadgets.The storage capacity of these cards may vary from 16 MB to 8 GB.

XD-Picture Card:
These cards are basically used in digital cameras for storing pictures.Original XD-cards come into various storage sizes ranging from 16 MB to 512 MB.

HTML-Hyper Text Markup Language

Introduction:
Every person familiar with intenet is expected to have heard about html.But many of us are not aware of its usage and requirement in the computer related work or to be more precised internet work.

HTML defined as hypertext markup language is a language which is basically used in computers is a language which is mainly used in files posted over the internet.These files are viewed using some special programs called web browsers.The text,graphics and design element of all web pages is a special code written by using various languages one of which is HTML and it defines the web browser how to display those files.

Requirement of HTML:
Every computer supports an operating system,some have windows as operating system installed in them,others have linux.According to one's requirement individuals install operating system in their computers.Connecting two or more computers with different operating systems installed on them is a big problem.To resolve this issue HTML was invented. to tranfer information on various machines having different Opertating system.HTML is designed in such a manner that its programming & function is understood by the web browsers.Every web browser supports HTML.

Advantages of HTML:

• Recognising files written in html is quite easy as every such file mostly has an extension .htm or .html.
• Apart from the content of the page,html file also defines the layout and formatting of the page.
• One important feature of an html file is that after finishing html document,it can easily be updated.
• Another advantage is that html files are easy to be sent on internet through email attachments.
  

Light Emitting Diode(LED)

Introduction:
LED is a semiconductor diode which emits light when electric current is passed through it.The basic usage of LED can be seen in vehicles as well as sometimes it is also used for home purpose.

Types of LED:
There are a number of types for LED.Among the various types of LED present and used around the world some of the commonly used are miniature,flashing,high power,multi color,alphanumeric LED,OLED.
Miniature is mostly used in indicator lights,it comes in various sizes from 2 m.m. to 10 m.m
The LED used in notebooks,PDAs,videogames,cellular phones,dvd players which is known as OLED(Organic Light Emitting Diode) is considered to be far better than LCD & CRT technology.The best part of it is that it can be used even in plastic films.

History of LED:
LED came into existence in 1907 during an experiment in the marcony lab by the british experimenter H.J. Round. Oleg Vladimirovich Losev created the first LED in the mid 1920.During that period,innovation of LED was not considered as a great achievement and hence the articles published in various Russian,German and British journals were never read.Thus this innovation was not used for exoeriments for many decades.
Then after years,Nick Holonyak Jr. who used to work with General Electric company designed the first visible spectrum LED in 1962.This spectrum was for red color.Nick Holonyak Jr. is considered as the father of LED since then.M.George Craford then created the Yellow and Red-Orange LED in 1972.These LEDs are used in watches,calculators,radio and various such electroninc items.

Advantages of using LED:

• LED is very beneficial to be used considering the fact that it saves a lot of energy.
  
• It is very small in size and hence can easily fit in printed circuit board.
• Unlike other sources,LED faces less wastage of energy.
• It can be used for a longer time period,according to a report on an average lifetime is somewhat about 35000 to 50000 hours.

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Web Browsers & their Functioning

Introduction:
This is a well known fact that every computer supports an operating system.Some systems have Windows as operating system whereas others have Linux/Unix.Selection of the Operating system depends on the indivisual's requirements.The programming for each operating system is entirely different along with unique functionalities.

Browser History:
In the starting period of computers,Variety of operating systems was a big issue to be resolved as it was difficult to connect two or more systems with different operating systems installed in them.Due to this reason it was a necessity to have a language which can effectively be executed on all operating systems.
The first language to overcome this issue was HTML(Hyper Text Markup Language).It was designed so that web browsers can ubderstand it easily.Every browser supports HTML.Earlier browsers use to support only HTML but nowadays there are many more similar languages such as XHTML.

BROWSER TECHNIQUE:
A webpage is located in the form of URL(Uniform Resource Locator) which is known as address .The webaddress starts with HTTP.Some browsers support other URL types and their protocols like Gopher,FTP etc.


Some popular Browsers:
Starting from 1991 with the first browser "world wide web" there are some other popular names like Mozaic,Internet Explorer,Netscape,Opera,Safari and Chrome.Apart from this the popular mobile browsers are Abaco,Nettamer,Qurel.Browsers known for some specific tasks are Flock,Image Explorer,Space time,Jack browser,Syndrome.Flock is very popular for searching networking sites,blogs,Photo share.Space time on the other hand is very popular for 3D searching on the web.

Compressed Natural Gas(C.N.G.)

Introduction:
Everyone must have heard about CNG.Natural gases are compressed to a range of 200-250 kg/cm^3 and this compressed state of natural gas is known as CNG.The reason why natural gas is compressed is that it takes occupies lesser space and provides adequaate pressure while entering the combustion chamber of the engine.
As CNG is another form of natural gas so it has the same chemical composition as of natural gas.Just like natural gas,even CNG is colorless,odourless and without any poison.It is slightly lighter then air.

Benefits of using CNG:
-This gas is considered more eco-friendly.As compared to petrol & diesel,it releases lesser carbon dioxide,nitrogen dioxide,and other harmful gases.Thus it plays a supporting role in keeping environment clean.

-It involves less expenditure as compared to petrol & diesel so considered economical.

Natural Gas:
Natural gas is considered as one of the best source for fuel.This gas is normally obtained during the extraction of petroleum from underground resources.It contains methane,ethane & propane.Along with these three gases it also contains butane,hectane,pentane in very small amount.All the gases listed above are considered to be very flamable hydro carbons.Apart form them carbon dioxide,nitrogen dioxide,helium and hydrogen sulphide are also contained by natural gas in impure forms.

Among various gaseous fuels,Natural gas has the highest mass.In India natural gas is mainly used as a fuel for home appliances and it is also used in vehicles in the form of CNG.

Voice Over Internet Protocol

Introduction:
VoIP(Voice over internet protocol)  is basically used for transmission technologies.In this technique the transmission of voice communication is done using the internet or packet-switched networks.Generally,IP telephony and Internet telephony are considered as synonyms for VoIP.If the internet service is available through some broadband network then it is termed as broadband telephony.Skype & Vonage are the well known service providers in this field.

History of VoIP:
In the world of technology and computers,VoIP has always attracted users .This technology was successfully tested in the year 1980 for the very first time.After a few years from this test that is in the year 1996,VocalTec(a software product) supported VoIP and also provided some additional services such as Voice mail and Caller Id.

Some of the advantages of using VoIP:

• VoIP reduces the cost of communication and infrastructure to a large extent.
• Problems like congestion in the network are normally not found in the I.P. network when using VoIP.
• Its not so easy to duplicate the VoIP network hence provides security.
• It supports the function where multiple telephone calls can be transmitted over the same broadband connection.
• VoIP can be merged with some other technologies and then services like conference calling,call forwarding,call routing,computer screen pops,caller-id and exchange of videos and data can be availed.
• On one hand where most of the telephones are connected to the phone line of the service providing company,VoIP are directly linked with the servers and hence there are very rare chances of any fault occurring in them.