3 NETWORK DEVICES I HAVE STUDIED ABOUT: 1- NETWORK HUB: An Ethernet hub, active hub, network hub, repeater hub, multiport repeater or hub is a device for connecting multiple Ethernet devices together and making them act as a single network segment. It has multiple input/output (I/O) ports, in which a signal introduced at the input of any port appears at the output of every port except the original incoming. A hub works at the physical layer (layer 1) of the OSI model.[1] The device is a form of multiport repeater. Repeater hubs also participate in collision detection, forwarding a jam signal to all ports if it detects a collision. Some hubs may also come with a BNC and/or Attachment Unit Interface (AUI) connector to allow connection to legacy 10BASE2 or 10BASE5 network segments. The availability of low-priced network switches has largely rendered hubs obsolete but they are still seen in 20th century installations and more specialized applications. FROM : http://en.wikipedia.org/wiki/Ethernet_hub 2- SWITCH: A network switch or switching hub is a computer networking device that connects network segments or network devices. The term commonly refers to a multi-port network bridge that processes and routes data at the data link layer (layer 2) of the OSI model. Switches that additionally process data at the network layer (layer 3) and above are often referred to as layer-3 switches or multilayer switches. The first Ethernet switch was introduced by Kalpana in 1990.[1] FROM: http://en.wikipedia.org/wiki/Network_switch 3- ROUTER: A router is a device that forwards data packets between computer networks, creating an overlay internetwork. A router is connected to two or more data lines from different networks. When a data packet comes in on one of the lines, the router reads the address information in the packet to determine its ultimate destination. Then, using information in its routing table or routing policy, it directs the packet to the next network on its journey. Routers perform the "traffic directing" functions on the Internet. A data packet is typically forwarded from one router to another through the networks that constitute the internetwork until it gets to its destination node.[1] The most familiar type of routers are home and small office routers that simply pass data, such as web pages and email, between the home computers and the owner's cable or DSL modem, which connects to the Internet through an ISP. More sophisticated routers, such as enterprise routers, connect large business or ISP networks up to the powerful core routers that forward data at high speed along the optical fiber lines of the Internet backbone. FROM : http://en.wikipedia.org/wiki/Router_(computing)

BLOGS: ((A blog (a portmanteau of the term web log)[1] is a personal journal published on the World Wide Web consisting of discrete entries ("posts") typically displayed in reverse chronological order so the most recent post appears first. Blogs are usually the work of a single individual, occasionally of a small group, and often are themed on a single subject. Blog can also be used as a verb, meaning to maintain or add content to a blog. The emergence and growth of blogs in the late 1990s coincided with the advent of web publishing tools that facilitated the posting of content by non-technical users. (Previously a knowledge of such technologies as HTML and FTP had been required to publish content on the Web.) Although not a must, most good quality blogs are interactive, allowing visitors to leave comments and even message each other via GUI widgets on the blogs and it is this interactivity that distinguishes them from other static websites.[2] In that sense, blogging can be seen as a form of social networking. Indeed, bloggers do not only produce content to post on their blogs but also build social relations with their readers and other bloggers.[3] Many blogs provide commentary on a particular subject; others function as more personal online diaries; yet still others function more as online brand advertising of a particular individual or company. A typical blog combines text, images, and links to other blogs, Web pages, and other media related to its topic. The ability of readers to leave comments in an interactive format is an important part of many blogs. Most blogs are primarily textual, although some focus on art (art blog), photographs (photoblog), videos (video blogging or vlogging), music (MP3 blog), and audio (podcasting). Microblogging is another type of blogging, featuring very short posts. As of 16 February 2011, there were over 156 million public blogs in existence.[4)) -AS SEEN ON :http://en.wikipedia.org/wiki/Blog

FORUMS:

An Internet forum, or message board, is an online discussion site where people can hold conversations in the form of posted messages.[1] They differ from chat rooms in that messages are at least temporarily archived. Also, depending on the access level of a user or the forum set-up, a posted message might need to be approved by a moderator before it becomes visible. Forums have a specific set of jargon associated with them; e.g. a single conversation is called a "thread". A discussion forum is hierarchical or tree-like in structure: a forum can contain a number of subforums, each of which may have several topics. Within a forum's topic, each new discussion started is called a thread, and can be replied to by as many people as so wish. Depending on the forum's settings, users can be anonymous or have to register with the forum and then subsequently log in in order to post messages. On most forums, users do not have to log in to read existing messages.

AS SEEN FROM: http://en.wikipedia.org/wiki/Internet_forum

WIKIS: ((A wiki (i/ˈwɪkiː/ wik-ee) is a website whose users can add, modify, or delete its content via a web browser using a simplified markup language or a rich-text editor.[1][2][3] Wikis are powered by wiki software. Most are created collaboratively. Wikis may serve many different purposes, such as knowledge management and notetaking. Wikis can be community websites and intranets, for example. Some permit control over different functions (levels of access). For example, editing rights may permit changing, adding or removing material. Others may permit access without enforcing access control. Other rules may also be imposed for organizing content. Ward Cunningham, the developer of the first wiki software, WikiWikiWeb, originally described it as "the simplest online database that could possibly work."[4] "Wiki" (pronounced [ˈwiti] or [ˈviti]) is an Hawaiian word meaning "fast" or "quick".[5])) -AS MENTIONED ON WIKIPEDIA. SOURCE : http://en.wikipedia.org/wiki/Wiki

ICT Homework.

DIGITAL DIVIDE:

As defined by Wikipedia, Digital divide refers to any inequalities between groups, broadly construed, in terms of access to, use of, or knowledge of information and communication technologies.The divide inside countries (such as the digital divide in the United States) can refer to inequalities between individuals, households, businesses, and geographic areas at different socioeconomic and other demographic levels, while the Global digital divide designates countries as the units of analysis and examines the divide between developing and developed countries on an international scale.

Digital divide is NOT a good phenomenon , it has many bad effects.. some of them are the following:
-People cant Communicate well with each other.
-People who are lacking behind will find it harder to live with all the new technologies than the educated people who quickly get used to new technologies.
-The Rich getting Richer at the Disadvantage of the Poor.


-The Rich getting Richer at the Disadvantage of the Poor.
The digital divide is not just a global divide it is a regional divide as well. The rich can afford internet access and advancements in technology. However the poorer members of society aren’t able to afford internet access payments and IT equipment. In essence the rich are getting richer with the advantage of access to the internet information and reaping the rewards of e-commerce and e-business, while the poorer members of society aren’t able to keep up.


Click [ HERE ] for a video about digital divide.

Pros and Cons of Simulation

Pros

There are two big advantages to performing a simulation rather than actually building the design and testing it. The biggest of these advantages is money. Designing, building, testing, redesigning, rebuilding, retesting,... for anything can be an expensive project. Simulations take the building/rebuilding phase out of the loop by using the model already created in the design phase. Most of the time the simulation testing is cheaper and faster than performing the multiple tests of the design each time. Considering the typical university budget cheaper is usually a very good thing. In the case of an electric thruster the test must be run inside of a vacuum tank. Vacuum tanks are very expensive to buy, run, and maintain. One of the main tests of an electric thruster is the lifetime test, which means that the thruster is running pretty much constantly inside of the vacuum tank for 10,000+ hours. This is pouring money down a drain compared to the price of the simulation.

The second biggest advantage of a simulation is the level of detail that you can get from a simulation. A simulation can give you results that are not experimentally measurable with our current level of technology. Results such as surface interactions on an atomic level, flow at the exit of a micro electric thruster, or molecular flow inside of a star are not measurable by any current devices. A simulation can give these results when problems such as it's too small to measure, the probe is too big and is skewing the results, and any instrument would turn to a gas at those temperatures come into the conversation. You can set the simulation to run for as many time steps you desire and at any level of detail you desire the only restrictions are your imagination, your programming skills, and your CPU.



Cons

There are two big disadvantages to performing a simulation as well. The first of these disadvantages is simulation errors. Any incorrect key stroke has the potential to alter the results of the simulation and give you the wrong results. Also usually we are programming using theories of the way things work not laws and theories are not often 100% correct. Provided that you can get your simulation to give you accurate results you must first run a base line to prove that it works. In order for the simulation to be accepted in the general community you have to take experimental results and simulate them. If the two data sets compare, then any simulation you do of your own design will have some credibility.

The other large disadvantage is the fact that it is a simulation. Many people do not consider what they do engineering unless they can see, hear, feel, and taste the project. If you are designing a light saber a typical engineer needs to be able to hold the light saber in their hand in order to consider the project worth his or her time. If you are capable of moving your craft into the virtual world of simulations you are no longer restricted by little things like reality. If you want to design a light saber in the virtual world it is not a problem, but in reality that is another matter all together. The virtual world is difficult to get use to the first time you use it for design, but after that the sky isn't even your limit

Process Flow Chart / System Flow Chart.

A system flowchart is a concrete, physical model that documents, in an easily visualized, graphical form, the system’s discrete physical components (its programs, procedures, files, reports, screens, etc.).

A system flowchart is a valuable presentation aid because it shows how the system’s major components fit together and interact. In effect, it serves as a system roadmap. During the information gathering stage, a system flowchart is an excellent tool for summarizing a great deal of technical information about the existing system. A system flowchart can also be used to map a hardware system.

System flowcharts are valuable as project planning and project management aids. Using the system flowchart as a guide, discrete units of work (such as writing a program or installing a new printer) can be identified, cost estimated, and scheduled. On large projects, the components suggest how the work might be divided into subsystems.

Historically, some analysts used system flowcharts to help develop job control language specifications. For example, IBM’s System/370 job control language requires an EXEC statement for each program and a DD statement for each device or file linked to each program. Consequently, each program symbol on the system flowchart represents an EXEC statement and each file or peripheral device symbol linked to a program by a flowline implies a need for one DD statement. Working backward, preparing a system flowchart from a JCL listing is good way to identify a program’s linkages.

A system flowchart’s symbols represent physical components, and the mere act of drawing one implies a physical decision. Consequently, system flowcharts are poor analysis tools because the appropriate time for making physical decisions is after analysis has been completed.

A system flowchart can be misleading. For example, an on-line storage symbol might represent a diskette, a hard disk, a CD-ROM, or some combination of secondary storage devices. Given such ambiguity, two experts looking at the same flowchart might reasonably envision two different physical systems. Consequently, the analyst’s intent must be clearly documented in an attached set of notes.


Here is a picture of how a system / process flow chart would look like: