Train brakes

In the air brake's simplest form, called the straight air system, compressed air pushes on a piston in a cylinder. The piston is connected through mechanical linkage to brake shoes that can rub on the train wheels, using the resulting friction to slow the train. The mechanical linkage can become quite elaborate, as it evenly distributes force from one pressurized air cylinder to 8 or 12 wheels.

The pressurized air comes from an air compressor in the locomotive and is sent from car to car by a train line made up of pipes beneath each car and hoses between cars. The principal problem with the straight air braking system is that any separation between hoses and pipes causes loss of air pressure and hence the loss of the force applying the brakes. This deficiency could easily cause a runaway train. Straight air brakes are still used on locomotives, although as a dual circuit system, usually with each bogie (truck) having its own circuit.

In order to design a system without the shortcomings of the straight air system, Westinghouse invented a system wherein each piece of railroad rolling stock was equipped with an air reservoir and a triple valve, also known as a control valve.

The triple valve is described as being so named as it performs three functions: Charging air into a air tank ready to be used, applying the brakes, and releasing them. In so doing, it supports certain other actions (i.e. it 'holds' or maintains the application and it permits the exhaust of brake cylinder pressure and the recharging of the reservoir during the release). In his patent application, Westinghouse refers to his 'triple-valve device' because of the three component valvular parts comprising it: the diaphragm-operated poppet valve feeding reservoir air to the brake cylinder, the reservoir charging valve, and the brake cylinder release valve. When he soon improved the device by removing the poppet valve action, these three components became the piston valve, the slide valve, and the graduating valve.

Weapons

India has worked to develop an autonomous military industry since independence was gained. Until now, success has been challenging, and despite design efforts in many areas, most resulting weapons have not completely met domestic requirements, nor become export successes india possesses nuclear weapons and maintains short- and intermediate-range ballistic missiles, nuclear-capable aircraft, surface ships, and submarines under development as possible delivery systems and platforms. Although it lacks an operational ballistic missile submarine, India has ambitions of possessing a nuclear triad in the near future when INS Arihant the lead ship of India's Arihant class ofnuclear-powered submarines formally joins the Indian Navy in 2012 after undergoing extensive sea-trials. Though India has not made any official statements about the size of its nuclear arsenal, recent estimates suggest that India has between 80 and 100 nuclear weapons,^[4]consistent with earlier estimates that it had produced enough weapons-grade plutonium for up to 75-110 nuclear weapons.^[5] Production of weapons-grade plutonium is believed to be taking place at the Bhabha Atomic Research Centre, which is home to the CIRUS reactor, acquired from Canada and shut down in 2010, to the indigenous Dhruva reactor, and to a plutonium separation facility.

India is not a signatory to the 1968 Nuclear Non-Proliferation Treaty (NPT), which India argues entrenches the status quo of the existing nuclear weapons states whilst preventing general nuclear disarmament.^[6] India tested a nuclear device in 1974 (code-named "Smiling Buddha"), which it called a "peaceful nuclear explosion." The test used plutonium produced in the Canadian-supplied CIRUS reactor, and raised concerns that nuclear technology supplied for peaceful purposes could be diverted to weapons purposes. This also stimulated the early work of the Nuclear Suppliers Group.^[7] India performed further nuclear tests in 1998 (code-named "Operation Shakti")

Virus

Do viruses and all the other nasties in cyberspace matter? Do they really do much harm? Imagine that no one has updated your anti-virus software for a few months. When they do, you find that your accounts spreadsheets are infected with a new virus that changes figures at random. Naturally you keep backups. But you might have been backing up infected files for months. How do you know which figures to trust?  Now imagine that a new email virus has been released. Your company is receiving so many emails that you decide to shut down your email gateway altogether and miss an urgent order from a big customer.  Imagine that a friend emails you some files he found on the Internet. You open them and trigger a virus that mails confidential documents to everyone in your address book including your competitors. Finally, imagine that you accidentally send another company, a report that carries a virus. Will they feel safe to do business with you again? Today new viruses sweep the planet in hours and virus scares are major news.

                             A computer virus is a computer program that can spread across computers and networks by making copies of itself, usually without the user’s knowledge. Viruses can have harmful side effects. These can range from displaying irritating messages to deleting all the files on your computer.

                             A virus program has to be run before it can infect your computer. Viruses have ways of making sure that this happens. They can attach themselves to other   programs or hide in code that is run automatically when you open certain types of files. The virus can copy itself to other files or disks and make changes on your computer. Virus side effects, often called the payload, are the aspect of most interest to users. Password-protecting the documents on a particular day, mailing information about the user and machine to an address somewhere are some of the harmful side effects of viruses. Various kinds of viruses include macro virus, parasitic or file virus, Boot virus,

                             E-mails are the biggest source of viruses. Usually they come as attachments with emails. The Internet caused the spreading of viruses around the globe. The threat level depends on the particular code used in the WebPages and the security measures taken by service providers and by you. One solution to prevent the viruses is anti-virus softwares. Anti-virus software can detect viruses, prevent access to infected files and often eliminate the infection.

                             Computer viruses are starting to affect mobile phones too. The virus is rare and is unlikely to cause much damage. Anti-virus experts expect that as mobile phones become more sophisticated they will be targeted by virus writers. Some firms are already working on anti-virus software for mobile phones. VBS/Timo-A, Love Bug,

Timofonica,

CABIR,

aka ACE-? and UNAVAILABLE are some of the viruses that affect the mobile phones

MPEG 7

Accessing audio and video used to be a simple matter - simple because of the simplicity of the access mechanisms and because of the poverty of the sources. An incommensurable amount of audiovisual information is becoming available in digital form, in digital archives, on the World Wide Web, in broadcast data streams and in personal and professional databases, and this amount is only growing. The value of information often depends on how easy it can be found, retrieved, accessed, filtered and managed.

          The transition between the second and third millennium abounds with new ways to produce, offer, filter, search, and manage digitized multimedia information. Broadband is being offered with increasing audio and video quality and speed of access. The trend is clear: in the next few years, users will be confronted with such a large number of contents provided by multiple sources that efficient and accurate access to this almost infinite amount of content seems unimaginable today. In spite of the fact that users have increasing access to these resources, identifying and managing them efficiently is becoming more difficult, because of the sheer volume. This applies to professional as well as end users. The question of identifying and managing content is not just restricted to database retrieval applications such as digital libraries, but extends to areas like broadcast channel selection, multimedia editing, and multimedia directory services.

          This challenging situation demands a timely solution to the problem. MPEG-7 is the answer to this need.

          MPEG-7 is an ISO/IEC standard developed by MPEG (Moving Picture Experts Group), the committee that also developed the successful standards known as MPEG-1 (1992) and MPEG-2 (1994), and the MPEG-4 standard (Version 1 in 1998, and version 2 in 1999). The MPEG-1 and MPEG-2 standards have enabled the production of widely adopted commercial products, such as Video CD, MP3, digital audio broadcasting (DAB), DVD, digital television (DVB and ATSC), and many video-on-demand trials and commercial services. MPEG-4 is the first real multimedia representation standard, allowing interactivity and a combination of natural and synthetic material coded in the form of objects (it models audiovisual data as a composition of these objects). MPEG-4 provides the standardized technological elements enabling the integration of the production, distribution and content access paradigms of the fields of interactive multimedia, mobile multimedia, interactive graphics and enhanced digital television.

          The MPEG-7 standard, formally named "Multimedia Content Description Interface", provides a rich set of standardized tools to describe multimedia content. Both human users and automatic systems that process audiovisual information are within the scope of MPEG-7.

          MPEG-7 offers a comprehensive set of audiovisual Description Tools (the metadata elements and their structure and relationships, that are defined by the standard in the form of Descriptors and Description Schemes) to create descriptions (i.e., a set of instantiated Description Schemes and their corresponding Descriptors at the users will), which will form the basis for applications enabling the needed effective and efficient access (search, filtering and browsing) to multimedia content. This is a challenging task given the broad spectrum of requirements and targeted multimedia applications, and the broad number of audiovisual features of importance in such context.

          MPEG-7 has been developed by experts representing broadcasters, electronics manufacturers, content creators and managers, publishers, intellectual property rights managers, telecommunication service providers and academia. 

What is Hacking? Who are Hackers?

     Eric Raymond, compiler of “The New Hacker's Dictionary”, defines a hacker as a clever programmer. A "good hack" is a clever solution to a programming problem and "hacking" is the act of doing it. Raymond lists five possible characteristics that qualify one as a hacker, which we paraphrase here:

● A person who enjoys learning details of a programming language or

system

● A person who enjoys actually doing the programming rather

than just theorizing about it
● A person capable of appreciating someone else's hacking
● A person who picks up programming quickly
● A person who is an expert at a particular programming language or system

Types of Hackers:

Hackers can be broadly classified on the basis of why they are hacking system or why the are indulging hacking. There are mainly three types of hacker on this basis

● Black-Hat Hacker

A black hat hackers or crackers are individuals with

extraordinary

computing skills, resorting to malicious or destructive activities. That is black hat hackers use their knowledge and skill for their own personal gains probably by hurting others.

● White-Hat Hacker

White hat hackers are those individuals professing hacker skills and using them for defensive purposes. This means that the white hat hackers use their knowledge and skill for the good of others and for the common good.● ●Grey-Hat Hackers

These are individuals who work both offensively and defensively at

various times. We cannot predict their behaviour. Sometimes they use their skills for the common good while in some other times he uses them for their personal gains.

ETHICAL HACKING

Ethical hacking – defined as “a methodology adopted by ethical hackers to discover the vulnerabilities existing in information systems’ operating environments.”

With the growth of the Internet, computer security has become a

major concern for businesses and governments.

In their search for a way to approach the problem, organizations came to realize that one of the best ways to evaluate the intruder threat to their interests would be to have independent computer security professionals attempt to break into their computer systems.

What do an Ethical Hacker do?

An ethical hacker is a person doing ethical hacking that is he is a security personal who tries to penetrate in to a network to find if there is some vulnerability in the system. An ethical hacker will always have the permission to enter into the target network. An ethical hacker will first think with a mindset of a hacker who tries to get in to the system.

He will first find out what an intruder can see or what others can see. Finding these an ethical hacker will try to get into the system with that information in whatever method he can. If he succeeds in penetrating into the system then he will report to the company with a detailed report about the particular vulnerability exploiting which he got in to the system. He may also sometimes make patches for that particular vulnerability or he may suggest some methods to prevent the vulnerability

A Guide to Internet Security: Becoming an Uebercracker

Author: Christopher Klaus <cklaus@shadow.net>
Date: December 5th, 1993.
Version: 1.1

  This is a paper will be broken into two parts, one showing 15 easy steps
to becoming a uebercracker and the next part showing how to become a
ueberadmin and how to stop a uebercracker.  A uebercracker is a term phrased
by Dan Farmer to refer to some elite (cr/h)acker that is practically
impossible to keep out of the networks.

Here's the steps to becoming a uebercracker.

Step 1. Relax and remain calm. Remember YOU are a Uebercracker.

Step 2. If you know a little Unix, you are way ahead of the crowd and skip
past step 3.

Step 3. You may want to buy Unix manual or book to let you know what
ls,cd,cat does.

Step 4. Read Usenet for the following groups: alt.irc, alt.security,
comp.security.unix.  Subscribe to Phrack@well.sf.ca.us to get a background
in uebercracker culture.

Step 5. Ask on alt.irc how to get and compile the latest IRC client and
connect to IRC.

Step 6. Once on IRC, join the #hack channel. (Whew, you are half-way
there!)

Step 7. Now, sit on #hack and send messages to everyone in the channel
saying "Hi, Whats up?". Be obnoxious to anyone else that joins and asks
questions like "Why cant I join #warez?"

Step 8. (Important Step) Send private messages to everyone asking for new
bugs or holes. Here's a good pointer, look around your system for binary
programs suid root (look in Unix manual from step 3 if confused). After
finding a suid root binary, (ie. su, chfn, syslog), tell people you have a
new bug in that program and you wrote a script for it.  If they ask how it
works, tell them they are "layme". Remember, YOU are a UeberCracker. Ask
them to trade for their get-root scripts.

Step 9. Make them send you some scripts before you send some garbage file
(ie. a big core file). Tell them it is encrypted or it was messed up and
you need to upload your script again.

Step 10. Spend a week grabbing all the scripts you can. (Dont forget to be
obnoxious on #hack otherwise people will look down on you and not give you
anything.)

Step 11. Hopefully you will now have atleast one or two scripts that get
you root on most Unixes. Grab root on your local machines, read your
admin's mail, or even other user's mail, even rm log files and whatever
temps you. (look in Unix manual from step 3 if confused).

Step 12. A good test for true uebercrackerness is to be able to fake mail.
Ask other uebercrackers how to fake mail (because they have had to pass the
same test). Email your admin how "layme" he is and how you got root and how
you erased his files, and have it appear coming from satan@evil.com.

Step 13. Now, to pass into supreme eliteness of uebercrackerness, you brag
about your exploits on #hack to everyone. (Make up stuff, Remember, YOU are
a uebercracker.)

Step 14. Wait a few months and have all your notes, etc ready in your room
for when the FBI, Secret Service, and other law enforcement agencies
confinscate your equipment. Call eff.org to complain how you were innocent
and how you accidently gotten someone else's account and only looked
because you were curious. (Whatever else that may help, throw at them.)

Step 15. Now for the true final supreme eliteness of all uebercrackers, you
go back to #hack and brag about how you were busted.  YOU are finally a
true Uebercracker.


Now the next part of the paper is top secret.  Please only pass to trusted
administrators and friends and even some trusted mailing lists, Usenet
groups, etc. (Make sure no one who is NOT in the inner circle of security
gets this.)

This is broken down on How to Become an UeberAdmin (otherwise know as a
security expert) and How to stop Uebercrackers.

Step 1. Read Unix manual ( a good idea for admins ).

Step 2. Very Important.  chmod 700 rdist; chmod 644 /etc/utmp. Install
sendmail 8.6.4.  You have probably stopped 60 percent of all Uebercrackers
now.  Rdist scripts is among the favorites for getting root by
uebercrackers.

Step 3. Okay, maybe you want to actually secure your machine from the
elite Uebercrackers who can break into any site on Internet.

Step 4. Set up your firewall to block rpc/nfs/ip-forwarding/src routing
packets. (This only applies to advanced admins who have control of the
router, but this will stop 90% of all uebercrackers from attempting your
site.)

Step 5. Apply all CERT and vendor patches to all of your machines. You have
just now killed 95% of all uebercrackers.

Step 6. Run a good password cracker to find open accounts and close them.
Run tripwire after making sure your binaries are untouched. Run tcp_wrapper
to find if a uebercracker is knocking on your machines.  Run ISS to make
sure that all your machines are reasonably secure as far as remote
configuration (ie. your NFS exports and anon FTP site.)

Step 7. If you have done all of the following, you will have stopped 99%
of all uebercrackers. Congrads! (Remember, You are the admin.)

Step 8. Now there is one percent of uebercrackers that have gained
knowledge from reading some security expert's mail (probably gained access
to his mail via NFS exports or the guest account.  You know how it is, like
the mechanic that always has a broken car, or the plumber that has the
broken sink, the security expert usually has an open machine.)

Step 9. Here is the hard part is to try to convince these security experts
that they are not so above the average citizen and that by now giving out
their unknown (except for the uebercrackers) security bugs, it would be a
service to Internet.  They do not have to post it on Usenet, but share
among many other trusted people and hopefully fixes will come about and
new pressure will be applied to vendors to come out with patches.

Step 10.  If you have gained the confidence of enough security experts,
you will know be a looked upto as an elite security administrator that is
able to stop most uebercrackers.  The final true test for being a ueberadmin
is to compile a IRC client, go onto #hack and log all the bragging and
help catch the uebercrackers. If a uebercracker does get into your system,
and he has used a new method you have never seen, you can probably tell
your other security admins and get half of the replies like - "That bug
been known for years, there just isn't any patches for it yet. Here's my
fix." and the other half of the replies will be like - "Wow.  That is very
impressive. You have just moved up a big notch in my security circle."
VERY IMPORTANT HERE:  If you see anyone in Usenet's security newsgroups
mention anything about that security hole, Flame him for discussing it
since it could bring down Internet and all Uebercrackers will now have it
and the million other reasons to keep everything secret about security.


Well, this paper has shown the finer details of security on Internet. It has
shown both sides of the coin.  Three points I would like to make that would
probably clean up most of the security problems on Internet are as the
following:

1.  Vendors need to make security a little higher than zero in priority.
If most vendors shipped their Unixes already secure with most known bugs
that have been floating around since the Internet Worm (6 years ago) fixed
and patched, then most uebercrackers would be stuck as new machines get
added to Internet.  (I believe Uebercracker is german for "lame copy-cat
that can get root with 3 year old bugs.") An interesting note is that
if you probably check the mail alias for "security@vendor.com", you will
find it points to /dev/null.  Maybe with enough mail, it will overfill
/dev/null.  (Look in manual if confused.)

2.  Security experts giving up the attitude that they are above the normal
Internet user and try to give out information that could lead to pressure
by other admins to vendors to come out with fixes and patches.  Most
security experts probably don't realize how far their information has
already  spread.

3.  And probably one of the more important points is just following the
steps I have outlined for Stopping a Uebercracker.


Resources for Security:
   Many security advisories are available from anonymous ftp cert.org.
Ask archie to find tcp_wrapper, security programs.  For more information
about ISS (Internet Security Scanner), email cklaus@shadow.net.


Acknowledgements:

   Thanks to the crew on IRC, Dan Farmer, Wietse Venema, Alec Muffet, Scott
Miles, Scott Yelich, and Henri De Valois.


Copyright:

This paper is Copyright 1993, 1994.  Please distribute to only trusted
people.  If you modify, alter, disassemble, reassemble, re-engineer or have
any suggestions or comments, please send them to:

cklaus@shadow.net

HPJava

The explosion of java over the last year has been driven largely by its in role in bringing a new generation of interactive web pages to World Wide Web. Undoubtedly various features of the languages-compactness, byte code portability, security, and so on—make it particularly attractive as an implementation languages for applets embedded in web pages. But it is clear that the ambition of the Java development team go well beyond enhancing the functionality of HTML documents.

             “Java is designed to meet the chalanges of application development on the context of heterogeneous, network-wide distributed environments. Paramaount amoung these chalanges is secure delivery of applications that consume the minimum of systems resources, can run on any hardware and software platform, can be extended dynamically.”

Several of these concerns are mirrored in developments in the High Prerformance Computing world over a number of years. A decade ago the focus of interest in the parallel computing community was on parallel hardware. A parallel computer was typically built from specialized processers through a proprietary high-performance communication switch. If the machine also had to be programmed in a proprietary language, that was an acceptable price for the benefits of using a supercomputer. This attitude was not sustainable as one parallel architecture gave way to another, and cost of porting software became exorbitant. For several years now, portability across platforms had been a central concern in parallel computing.

HPJava is a programming language extended from Java to support parallel programming, especially (but not exclusively) data parallel programming on message passing and distributed memory systems, from multi-processor systems to workstation clusters.

Although it has a close relationship with HPF, the design of HPJava does not inherit the HPF programming model. Instead the language introduces a high-level structured SPMD programming style--the HPspmd model. A program written in this kind of language explicitly coordinates well-defined process groups. These cooperate in a loosely synchronous manner, sharing logical threads of control. As in a conventional distributed-memory SPMD program, only a process owning a data item such as an array element is allowed to access the item directly. The language provides special constructs that allow programmers to meet this constraint conveniently.

Besides the normal variables of the sequential base language, the language model introduces classes of global variables that are stored collectively across process groups. Primarily, these are distributed arrays. They provide a global name space in the form of globally subscripted arrays, with assorted distribution patterns. This helps to relieve programmers of error-prone activities such as the local-to-global, global-to-local subscript translations which occur in data parallel applications.

In addition to special data types the language provides special constructs to facilitate both data parallel and task parallel programming. Through these constructs, different processors can either work simultaneously on globally addressed data, or independently execute complex procedures on locally held data. The conversion between these phases is seamless.

            In the traditional SPMD mold, the language itself does not provide implicit data movement semantics. This greatly simplifies the task of the compiler, and should encourage programmers to use algorithms that exploit locality. Data on remote processors is accessed exclusively through explicit library calls. In particular, the initial HPJava implementation relies on a library of collective communication routines originally developed as part of an HPF runtime library. Other distributed-array-oriented communication libraries may be bound to the language later. Due to the explicit SPMD programming model, low level MPI communication is always available as a fall-back. The language itself only provides basic concepts to organize data arrays and process groups. Different communication patterns are implemented as library functions. This allows the possibility that if a new communication pattern is needed, it is relatively easily integrated through new libraries.

2.  Overview of HPJava

                       

HPJava stands for “high performance java”. Java already provides parallelism through threads. But that model of parallelism can only be easily exploited on shared memory computers. HPJava is targetted at distributed memory parallel computers (most likely, networks of PCs and workstations). 

 Java packages for HPspmd programming

The current runtime interface for HPJava is called adJava. It consists of two Java packages. The first is the HPspmd runtime proper. It includes the classes needed to translate language constructs. The second package provides communication and some simple I/O functions. These two packages will be outlined in this section.

The classes in the first package include an environment class, distributed array ``container classes'', and related classes describing process groups and index ranges. The environment class SpmdEnv provides functions to initialize and finalize the underlying communication library (currently MPI). Constructors call native functions to prepare the lower level communication package. An important field, apg, defines the group of processes that is cooperating in ``loose synchrony'' at the current point of execution.

The other classes in this package correspond directly to HPJava built-in classes. The first hierarchy is based on Group. A group, or process group, defines some subset of the processes executing the SPMD program. Groups have two important roles in HPJava. First they are used to describe how program variables such as arrays are distributed or replicated across the process pool. Secondly they are used to specify which subset of processes execute a particular code fragment. Important members of adJava Group class include the pair on(), no() used to translate the on construct. 

Ipad

The iPad is a tablet computer designed and marketed by Apple for Internet browsing, media consumption, gaming, and light content creation. Released in April 2010, it established a new class of devices between smartphones and laptops.

              Similar to the older (and smaller) iPod Touch and iPhone, the iPad runs a modified version of the iPhone OS and is controlled by a multi-touch LCD sensitive to fingertips, instead of a stylus as with earlier tablet computers.  It runs iPad-specific applications as well as those written for the iPhone and iPod Touch, including e-book readers.
          The iPad uses Wi-Fi or a 3G data connection to browse the Internet, load and stream media, and install software.  A USB cable is required to sync the iPad with iTunes on a personal computer.

   SOFTWARE

              Like the iPhone, with which it shares a development environment (iPhone SDK, or software development kit, version 3.2 onwards),  the iPad only runs its own software, software downloaded from Apple's App Store, and software written by developers who have paid for a developer's license on registered devices.  The iPad runs almost all third-party iPhone applications, displaying them at iPhone size or enlarging them to fill the iPad's screen.  Developers may also create or modify apps to take advantage of the iPad's features. Application developers use iPhone SDK for developing applications for iPad.

  AUDIO AND OUTPUT

           Dual speakers housed inside the iPad provide mono sound via two small sealed channels in the interior speaker assembly that direct the sound outwards toward the three audio ports carved into the bottom-right of the unit. The microphone is within the device. A volume switch is on the right side of the unit, and a 3.5 mm TRS connector audio-out jack provides stereo sound for headphones on the top-left corner of the device. The iPad supports normal headphones and models with microphones, volume controls, or both. Microphones can be used for voice recording.

The built-in Bluetooth 2.1 + EDR interface supports the HSP, A2DP, and HID profiles, which allow wireless headphones and keyboards to be used with the iPad. However, the iPhone OS does not currently support the OBEX file transfer protocol.

iPad video output over VGA is set to 1024 x 768 using a 720p scan rate.

   SCREEN AND INPUT

The touchscreen is a 25 cm (9.7 in) liquid crystal display (1024 × 768 pixels, 132 ppi, XGA) with fingerprint–resistant and scratch-resistant glass. Like the iPhone, the iPad is designed to be controlled by bare fingers; normal gloves and styli that prevent electrical conductivity may not be used  although there are special gloves and styli designed for this use.
The display responds to two other sensors: an ambient light sensor to adjust screen brightness and a 3-axis accelerometer to sense iPad orientation and switch between portrait and landscape modes. Unlike the iPhone and iPod touch built-in applications, which work in three orientations (portrait, landscape-left and landscape-right), the iPad built-in applications support screen rotation in all four orientations (the three aforementioned ones along with upside-down), ^] meaning that the device has no intrinsic "native" orientation; only the position of the home button changes. Most third-party iPad applications also support these four orientations.
The iPad has a switch to lock out this screen rotation function (reportedly to prevent unintended rotation when the user is lying down).  There are a total of four physical switches, including a home button below the display that returns the user to the main menu, and three plastic physical switches on the along with the screen rotation lock.

   CONNECTIVITY

The iPad can use Wi-Fi network trilateration from Skyhook Wireless to provide location information to applications such as Google Maps.  The 3G model contains A-GPS while both models have a digital compass.
The back of the Wi-Fi model iPad is made of contoured aluminum with black plastic buttons. The Wi-Fi + 3G model also has a black plastic accent on top of the device which helps with 3G radio sensitivity.

   POWER AND BATTERY

The iPad uses an internal rechargeable lithium-ion polymer battery. The batteries are made in Taiwan by Simplo Technology, which makes 60% of them, and Dynapack International Technology.  The iPad is designed to be charged with a high current (2 amperes) using the included USB 10 W power adapter. While it can be charged by a standard USB port from a computer, these typically provide lower current (500 milliamperes or 1 ampere). As a result, if the iPad is turned on while being charged with a normal USB computer port, it will charge much more slowly, if at all.

Apple claims that the iPad's battery can provide up to 10 hours of video, 140 hours of audio playback, or one month on standby. The battery loses capacity over time and is not designed to be user-replaceable. As in the battery-replacement program for iPod and the original iPhone, Apple will replace an iPad that does not hold an electrical charge with a refurbished iPad for a fee of US$99.

 STORAGE AND SIM

            The iPad was released with three options for internal storage size: a 16, 32, or 64 GB flash drive. All data are stored on the flash drive and there is no option to expand storage. Apple sells a camera connection kit with an SD card reader, but it can only be used to transfer photos and videos.

The side of the Wi-Fi + 3G model has a micro-SIM slot (not mini-SIM). The 3G model may be used with an AT&T data plan that does not require a contract,  Unlike the iPhone, which is usually sold locked to specific carriers, the 3G iPad is sold unlocked and can be used with any compatible GSM carrier. In the U.S., data network access via T-Mobile's network is limited to slower EDGE cellular speeds because T-Mobile's 3G Network uses different frequencies.

   APPLICATIONS

           Apple developed the iPad with an improved functionality over that of the iPhone and iPod Touch. The iPad comes with several applications such as Safari, Mail, Photos, Video, YouTube, iPod, iTunes, App Store, iBooks, Maps, Notes, Calendar, Contacts, and Spotlight Search.  These applications were borrowed from iPhone’s third generation OS, but improved for the iPad. However, the iPad doesn’t run the iPhone’s 3.1.2 OS and neither the Mac OS X, but an improved version of the third generation iPhone OS, iPhone OS v3.2. Moreover, the iPad will receive the latest iPhone OS, iPhone OS 4 within the fall of 2010.
The iPad syncs with iTunes on a Mac or Windows PC. Apple ported its iWork suite from the Mac to the iPad, deleting several features in the process, and sells the Pages, Numbers, and Keynote apps in the App Store.  Although the iPad is not designed to replace a cellphone, a user can pair it with a Bluetooth headset and place phone calls over Wi-Fi or 3G using a VoIP application.

Ambiophonics

Ambiophonics (not to be confused with Ambisonics) is a method in the public domain that                     employs digital signal processing (DSP) and two loudspeakers directly in front of the listener in order to improve reproduction of stereophonic and 5.1 surround sound for music, movies, and games in home theaters, gaming PCs, workstations, or studio monitoring applications. First implemented using mechanical means in 1986 [1][2], today a number of hardware and VST plug-in makers offer Ambiophonic DSP [3]. Ambiophonics eliminates crosstalk inherent in the conventional “stereo triangle” speaker placement, and thereby generates a speaker-binaural soundfield that emulates headphone-binaural, and creates for the listener improved perception of “reality” of recorded auditory scenes. A second speaker pair can be added in back in order to enable 360° surround sound reproduction. Additional surround speakers may be used for hall ambience, including height, if desired.

Ambiophonics, stereophonics, and human hearing

In stereophonics, the reproduced sound is distorted by crosstalk, where signals from either speaker reach not only the intended ear, but the opposite ear, causing comb filtering that distorts timbre of central voices, and creating false “early reflections” due to the delay of sound reaching the opposite ear. In addition, auditory images are bounded between left (L) and right (R) speakers, usually positioned at ±30° with respect to the listener, thereby including 60°, only 1/6 of the horizontal circle, with the listener at the center. (It should be noted that human hearing can locate sound from directions not only in a 360° circle, but a full sphere.)

Ambiophonics eliminates speaker crosstalk and its deleterious effects. Using ambiophonics, auditory images can extend in theory all the way to the sides, at ±90° left and right and including the front hemi-circle of 180°, depending on listening acoustics and to what degree the recording has captured the interaural level differences (ILD) and the interaural time differences (ITD) that characterize two-eared human hearing. Most existing two channel discs (LPs as well as CDs) include ILD and ITD data that cannot be reproduced by the stereo loudspeaker “triangle” due to inherent crosstalk. When reproduced using ambiophonics, such existing recordings’ true qualities are revealed, with natural solo voices and wider images, up to 150° in practice.

It is also possible to make new recordings using binaurally-based main microphones, such as an ambiophone,[3] which is optimized for Ambiophonic reproduction (stereo-compatible) since it captures and preserves the same ILD and ITD that one would experience with one’s own ears at the recording session. Along with life-like spatial qualities, more correct timbre (tone color) of sounds is preserved. Use of ORTF, Jecklin Disk, and sphere microphones without pinna (outer ear) can produce similar results. (Note that microphone techniques such as these that are binaural-based but without pinna also produce compatible results using conventional speaker-stereo, 5.1 surround, and mp3 players.)

[edit]Roots & research

Ambiophonics is an amalgam of new research and previously known psychoacoustic principles and binaural technologies. This knowledge has enabled audio recording and reproduction that approaches the realistic soundfield at the ears of the listener that is comparable to what one would perceive in a concert hall, movie scene, or game environment. This level of high-fidelity was not realizable until human hearing and acoustics principles were thoroughly researched, and affordable PCs with sufficient processing speed became available. At the Casa Della Musica at the University of Parma, Italy, or at the listening lab at Filmaker Technology, Pennsylvania USA, ambiophonics, ambisonics, stereophonics, 5.1 2D surround, and hybrid full-sphere 3D systems can be compared for the abilities of these methods to convey the spatiality and tone color of real perception. Developers have provided many scientific papers and downloadable tools for implementing ambiophonics free of charge for personal use.[4]

[edit]Results & limitations

By repositioning speakers closer together, and using digital signal processing (DSP) such as free RACE (Recursive Ambiophonic Crosstalk Elimination) or similar software,[5] ambiophonic reproduction is able to generate wide auditory images from most ordinary CDs/LPs/DVDs or MP3s of music, movies, or games and, depending upon the recording, restore the life-like localization, spatiality, and tone color they have captured. For most test subjects, results are dramatic, suggesting that Ambiophonics has the potential to revitalize interest in high-fidelity sound reproduction, both in stereo and surround.

Additionally, ambiophonics provides for the optional use of concert-hall or other ambience impulse response convolution to generate hall ambience signals for virtually any number and any placement of surround speakers.[6][7] But ambiophonics is not for theaters, auditoriums, or any large groups. Ambiophonics can usually accommodate more than one listener since one can move back and forth along the line bisecting the speakers. Precisely because of the higher level of envelopment along this line, the loss of realism when one moves away from the center line is more dramatic in the case of Ambiophonics than stereo. The listening area can be enlarged with ambience convolution, whereby surround speakers mimic the contributions of concert-hall walls.

Ambiophonics methods can be implemented in ordinary laptops, PCs, soundcards, hi-fi amplifiers, and even modest loudspeakers with consistent phase response, especially in any crossover regions. Neither true-binaural (dummy head with pinna) recordings nor head tracking are required, as with headphone-binaural listening. Commercial products now implement ambiophonics DSP, although tools for use on PCs are also available online.[4]

[edit]Surround sound

In practice in its simplest two-speaker implementation, ambiophonic reproduction unlocks auditory cues for images of up to 150° horizontally (azimuth), depending on the binaural cues captured in existing stereo recordings. Multi-channel recordings made with ambiophone-like microphone arrays to make 5.1-compatible DVD/SACD recordings can be reproduced using just four speakers (a center speaker is obviated in ambiophonic layouts). Allowing for the human hearing “cone of confusion” at each side, a full 360° degree circle of perceived sound localization has been measured within ±5° of actual source azimuth, reproducing life-like spatial envelopment and timbre (contributed by accurate directional provenance of early reflections) of multi-channel music, movies, and game content.[3][8][9]

Especially in the case of stereo content where ambience has been purposely reduced (because a natural level coming from front 60°-only is perceived as too much), additional signals for surround speakers can be produced using a measured hall impulse response, convolved in a PC with the two front channel signals. For full ambiophonic replay, one PC can provide the DSP for 4-channel crosstalk-cancellation and four or more (up to 16 depending on the PC) surround speakers.[10]

The development of ambiophonics is the work of several researchers and companies including Ralph Glasgal, founder of the Ambiophonic Institute; Dr. Angelo Farina, University of Parma; Robin Miller, Filmaker Technology; Waves Audio; Dr. Roger West, Soundlab; Dr. Radomir Bozovic, TacT Audio; and Prof. Edgar Choueiri, Princeton University.