All About Technology

ENERGY

2016-01-22T22:44:00.000+01:00

ENERGY

Energy is seen everywhere, it can be visualized in form of substances, felt in the case of kicking a soccer ball, but can’t be felt, seen, smell or heard in a direct way, all we perceive are its effects.

Energy takes different forms, kicking a ball, which is kinetic energy (energy in motion), a boy standing which is potential energy (energy at rest), a ball falling (gravitational energy), energy stored in petrol (chemical energy), energy in an elastic rubber (elastic energy), movement of piston in automobile engine (mechanical energy), energy from the sun (solar energy), energy produced by reacting radioactive elements (nuclear energy), energy in wires carry current (electrical energy).

These multiple forms of energy can be converted into each other. A match stick converts chemical energy into heat energy. Which brings about the law which states, energy can be transferred from one form to another, but cannot be created nor destroyed. Which is the first law of thermodynamics, the law of conservation of energy.

FORMS OF ENERGY

There are many forms of energy but basically they fall under these two categories, the potential and kinetic energy.

POTENTIAL ENERGY

Potential energy is energy at rest or of position, some of it’s forms are:

CHEMICAL ENERGY

it is energy stored in bonds of atoms of molecules, plants releases its chemical energy through the process of photosynthesis.

NUCLEAR ENERGY

Energy stored in the nucleus of an atom, the energy that holds the nucleus together. The energy can be released when the nuclei are combined or split apart.

GRAVITATIONAL ENERGY

Energy of position or place. A rock resting at the top of a hill contains gravitational potential energy. Hydropower, such as water in a reservoir behind a dam, is an example of gravitational potential energy.

KINETIC ENERGY

Kinetic energy is the energy in motion, the motion of wind, waves, molecules e.t.c

ELECTRICAL ENERGY

The movement of electrons. Everything is made of tiny particles called atoms. Atoms are made of even smaller particles called electrons, protons, and neutrons. Applying a force can make some of the electrons move. Electrons moving through a wire are called electricity.

THERMAL OR HEAT ENERGY

The internal energy in substances, the vibration and movement of atoms and molecules within substances. The faster molecules and atoms vibrate and move within substances, the more energy they possess and the hotter they become. Geothermal energy is an example of thermal energy.

SOUND ENERGY

The movement of energy through substances in longitudinal (compression/rarefaction) waves. Sound is produced when a force causes an object or substance to vibrate. The energy is transferred through the substance in a wave.

SOURCES OF ENERGY

The sources of energy can be classified into two namely: Renewable and non-renewable energy.

NONRENEWABLE ENERGY

These energy sources are called nonrenewable because they cannot be replenished in a short period of time. Sources include coal, petroleum, natural gas, propane, and uranium. They are used to generate electricity, to heat our homes, to move our cars, and to manufacture products.

RENEWABLE ENERGY

Sources include biomass, geothermal, hydropower, solar, and wind. They are called renewable energy sources because their supplies are replenished in a short time.

3D Printing

2016-01-21T22:10:00.000+01:00

3D printing or additive manufacturing is a process of making three dimensional solid objects from a digital file. It is additive because it is created by adding successive layers of materials until the whole object is created.
Firstly, a virtual design of the object you want to create. This virtual design is made in a CAD (Computer Aided Design) file using a 3D moelling program (for the creation of a totally new object) or with the use of a 3D scanner (to copy an existing object). A 3D scanner makes a 3D digital copy of an object.

Processes and mechanisms

All 3D printers don't use the same technology. There are several ways to print and all those available are additive, differing mainly in the way layers are build to create the final object.
Some methods use melting or softening material to produce the layers. The most common technologies using this method for printing are the Selective laser sintering (SLS) and fused deposition modeling (FDM). Another method of printing is when we talk about curing a photo-reactive resin with a UV laser or another similar power source one layer at a time, stereolithography (SLA) is the most common printer using this technology.

Examples & applications of 3D printing

Applications include rapid prototyping, architectural scale models & maquettes, healthcare (3d printed prosthetics and printing with human tissue) and entertainment (e.g. film props).
Other examples of 3D printing would include reconstructing fossils in paleontology, replicating ancient artifacts in archaeology, reconstructing bones and body parts in forensic pathology and reconstructing heavily damaged evidence acquired from crime scene investigations.

OCULUS......How it Works

2016-01-20T16:57:00.002+01:00

The device is a lightweight virtual reality headset that blocks your view of your surroundings and fully immerses you in a virtual world. The Rift lets you step into a game, look around in any direction and see the game environment all around you. And you see it in 3D.

Technical Specifications

The Oculus Rift Development Kit version 1.1 includes the Oculus Rift head set, which resembles a pair of black ski goggles with a rectangular box covering the front end. The kit also comes with a control box that's permanently attached to the headset via a 6-foot (1.8-meter) cable, a removable over-the-head strap for added comfort and stability, three pairs of vision lenses of different focal lengths, an HDMI cable, a USB cable, a DVI cable, an HDMI to DVI adapter and a 5-Volt switching US-standard power supply along with international power adapters. All of this comes housed in a hard case. The Oculus Rift dev kit goggles weigh 369 grams and the future consumer model may be even lighter.
The control box is used to hook the headset up to your computer and perform basic control functions. It includes HDMI, DVI, mini-USB and DC power connection ports, as well as five buttons for controlling contrast, brightness and power. A blue LED on top shows you whether the device is on or off.
The developer headset allows for head-tracking with 3 degrees of freedom (DOF), ultra-low latency and a field of view (FOV) of 110 degrees diagonally and 90 degrees horizontally for convincing immersion.
The Rift incorporates a flat 7-inch (17.8-centimeter) 60Hz LCD display screen with a resolution of 1280 by 800 pixels (around 720p high-def resolution). The screen is divided into 640 by 800 pixels per eye, with a 2.5-inch (64-millimeter) fixed distance between lens centers. The user views the screen through two lens cups. There are plans to make the consumer model's resolution at least 1080p, and the company has already demonstrated two 1080p prototypes (the HD and Crystal Cove models). The display inputs include DVI-D Single Link, HDMI 1.3+ and USB 2.0 Full Speed+, all fed to it through the single control box cord.
The device has a custom-built motion and orientation sensor unit with a sampling rate of up to 1000 Hz. The sensor unit includes a gyroscope, an accelerometer and a magnetometer, along with an ARM Cortex-M3 microcontroller. The data from all three sensors is combined through a process called sensor fusion to enable fast and accurate tracking of your head orientation and synchronization with what you are viewing. This allows you to turn your head in any direction and look around the virtual environment in real-time, but it doesn't allow for positional tracking.
A new prototype, dubbed Crystal Cove, debuted at CES 2014. It has a higher resolution 1080p AMOLED (active matrix organic light emitting diode) screen, lower latency, a higher refresh rate and much lower image persistence, meaning that the images you see on the screen change as quickly as you move rather than persisting on the screen long enough to cause a lot of motion blurring. Crystal Cove can also track position, rather than just orientation, with the help of IR LEDs (which look like little square white dots) all over the headset that are monitored by an external camera, giving you 6 degrees of freedom rather than just 3. You can lean toward things to get a closer look, or lean to look around corners, whereas with the developer kit you can turn your head in various directions to change the camera view, but you have to use a separate controller to handle all motion toward, away from or around things. This prototype is reportedly closer to Oculus VR's vision for the consumer version.

System Requirements

Although there are no specific minimum requirements, but the following could be guidelines

Windows (Vista, 7 or 8)
Mac OS 10.6 or higher
Linux (Ubuntu 12.04 LTS)
2.0+ GHz processor
2 GB RAM
Direct3D 10 or OpenGL 3 compatible video card

Sources

http://electronics.howstuffworks.com/oculus-rift9.htm

Soccer Boots; The Shoe Lace Effect

2016-01-19T21:38:00.001+01:00

History

Modern soccer shoes could be traced to the Dassler shoe introduced in 1954 by Adi Dassler, founder of Adidas. It is made to be lighter than the conventional shoes. Most important to kicking was the introduction of screw-in studs to match the stud length to the sloppiness of the playing field, important especially in rainy conditions.

The type of sole: outdoor cleats are molded thermoplastic polyurethanes and indoor shoes are gum rubber.
stud configuration: this can lead to a 250% change in the degree of traction offered, players need shoe that is neither too slippery, so that they don't risk falling, nor too grippy, posing a danger that players will suffer knee and ankle injuries as their feet become locked during turns and maneuvers.

BITCOIN!!! what you need to know about it

2016-01-18T21:44:00.002+01:00

They're a bit like money, they are generally defined as a type of virtual currency, brought to life by the Internet. Bitcoins share many similarities with other currencies, but the most important one is that more and more merchants, retailers and individuals, both online and offline, accept bitcoins as payment. You can buy pizza with bitcoins, subscribe to an online dating service, or even shop at your favorite superstore.

For new users

Being a new user, you can use Bitcoin without understanding much of the technical details. All you need do is to install a Bitcoin wallet on your computer or mobile phone, it will generate your first Bitcoin address and you can create more whenever you need one. You can disclose your addresses to your friends so that they can pay you or vice versa. In fact, this is pretty similar to how email works, except that Bitcoin addresses should only be used once.

Balances - block chain

The block chain is a shared public ledger on which the entire Bitcoin network relies. All confirmed transactions are included in the block chain. This way, Bitcoin wallets can calculate their spendable balance and new transactions can be verified to be spending bitcoins that are actually owned by the spender.

Transactions - private keys

A transaction is a transfer of value between Bitcoin wallets that gets included in the block chain. Bitcoin wallets keep a secret piece of data called a private key or seed, which is used to sign transactions, providing a mathematical proof that they have come from the owner of the wallet. The signture also prevents the transaction from being altered by anybody once it has been issued. All transactions are broadcast between users and usually begin to be confirmed by the network in the following 10 minutes, through a process called mining.

Processing - mining

Mining is a distributed consensus system that is used to confirm waiting transactions by including them in the block chain. It enforces a chronological order in the block chain, protects the neutrality of the network, and allows different computers to agree on the state of the system. To be confirmed, transactions must be packed in a block that fits very strict cryptographic rules that will be verified by the network. These rules prevent previous blocks from being modified because doing so would invalidate all following blocks. Mining also creates the equivalent of a competitive lottery that prevents any individual from easily adding new blocks consecutively in the block chain. This way, no individuals can control what is included in the block chain or replace parts of the block chain to roll back their own spends.

Navigating through your computer easily....try this!!

2016-01-17T15:32:00.000+01:00

Study shows that about 90 percent of computer users don't know about using shortcut keys to browse around computer, you mouse might be faulty, you will just mange the keyboard for a quickie!!
here are some of the shortcuts and their descriptions:
Alt + F: File menu options in current program.
Alt + E: Edit options in current program
F1: Universal Help in almost every Windows program.
Ctrl + A: Select all text.
Ctrl + X: Cut
Shift + Del: Cut selected item.
Ctrl + C: Copy selected item.
Ctrl + Ins: Copy selected item.
Ctrl + V: Paste selected item.
Shift + Ins: Paste.
Home: Goes to beginning of current line.
Ctrl + Home: Goes to beginning of document.
End: Goes to end of current line.
Ctrl + End: Goes to end of document.
Shift + Home: Highlights from current position to beginning of line.
Shift + End: Highlights from current position to end of line.
Ctrl + Left arrow: Moves one word to the left at a time.
Ctrl + Right arrow: Moves one word to the right at a time.
Shortcut Keys and their Functions: Below is a listing of all the major shortcut keys in Microsoft Word.
Shortcut Keys and their Descriptions
Ctrl + A: Select all contents of the page.
Ctrl + B: Bold highlighted selection.
Ctrl + C: Copy selected text.
Ctrl + X: Cut selected text.
Ctrl + P: Open the print window.
Ctrl + F: Open find box.
Ctrl + I: Italic highlighted selection.
Ctrl + K: Insert link (Shortcut Keys and their Functions).
Ctrl + U: Underline highlighted selection.
Ctrl + V: Paste.
Ctrl + Y: Redo the last action performed.
Ctrl + Z: Undo last action.
Ctrl + L: Aligns the line or selected text to the left of the screen.
Ctrl + E: Aligns the line or selected text to the center of the screen.
Ctrl + R: Aligns the line or selected text to the right of the screen.
Ctrl + M: Indent the paragraph.
Ctrl + Shift + F: Change the font.
Ctrl + Shift + >: Increase selected font +1pts up to 12pt and then increases font +2pts.
Ctrl + ]: Increase selected font +1pts.
Ctrl + Shift + <: Decrease selected font -1pts if 12pt or lower, if above 12 decreases font by +2pt.
Ctrl + [: Decrease selected font -1pts.
Ctrl + Shift + *: View or hide non printing characters.
Ctrl + L: Moves one word to the left.
Ctrl + R: Moves one word to the right.
Ctrl + : Moves to the beginning of the line or paragraph.
Ctrl + : Moves to the end of the paragraph.
Ctrl + Del: Deletes word to right of cursor.
Ctrl + Backspace: Deletes word to left of cursor.
Ctrl + End: Moves the cursor to the end of the document.
Ctrl + Home: Moves the cursor to the beginning of the document.
Ctrl + Spacebar: Reset highlighted text to the default font.
Ctrl + 1: Single-space lines.
Ctrl + 2: Double-space lines.
Ctrl + 5: 1.5-line spacing.
Ctrl + Alt + 1: Changes text to heading 1.
Ctrl + Alt + 2: Changes text to heading 2.
Ctrl + Alt + 3: Changes text to heading 3.
Alt + Shift + D: Insert the current date.
Alt + Shift + T: Insert the current time.

NEVER GIVE HACKERS THE CHANCE TO MESS THINGS UP

2016-01-15T18:40:00.000+01:00

The internet is full of scammers, vagabonds, lazy-ass people who want to steal from you, never give them the access to damage your reputation and your hard earned money, here are some tips to keep things safe on the internet:

1. Don't be a fool

Refer 10 people and get $500, that sounds cool, but beware!!! they might be scammers who just want to use you to launder money around, and might want to use your account details. Don't be too covetous

2. Always use a strong password

So many people like to use passwords that are easy to remember, not bad!, but it might just be too easy to hack, i will advise you to take extra steps to add more special characters to it like figures, punctuation to your password.

3. Mind the transactions you carry out on social networks

Always carryout your transactions via your banking platforms and not totally on your social media platform, also don't click on unnecessary adverts.

4. Use different emails

it is advisable to keep you business transaction emails differently from your social media emails, they say it's not advisable to put all eggs in a basket.

5. Cautions

whenever you suspect any activities on your account, change your password immediately, report to the website.

Phone Camera: More Megapixels isn't always better

2016-01-13T20:19:00.000+01:00

A 13 megapixel smartphone camera might sound great, but a 8 megapixel shooter will do better due to the following reasons.

sensor

This is the part that captures the light. The sensor is essentially the "film" material of a digital camera. No light, no photo.
Light enters through the camera lens, then passes to the camera sensor, which receives the information and translates it into an electronic signal. From there, the image processor creates the image and fine-tunes it to correct for a typical set of photographic flaws, like noise.
The size of the image sensor is extremely important. In general, the larger the sensor, the larger your pixels, and the larger the pixels, the more light you can collect. The more light you can catch, the better your image can be.
Larger sensors are the reason that 8 megapixels from a digital camera is better than those 8 megapixels from a smartphone camera. You get roughly the same number of pixels, but the pixels on the digital camera get to be larger, and therefore let in more light. More light equals less-noisy images and greater dynamic range.

Image processor

Most modern high-end smartphone CPUs have dedicated graphics processors built into the chip, which, being hardware-accelerated and not just software-dependent, can quickly render images like photos, videos, and games without overtaxing the main application processor.

The user

The user's ability to snap under perfect exposure, i.e the direction of light, composure, also determines how good the outcome of pictures can be. Recently, some phones have the ability to detect faces, smiles e.t.c which makes pictures to look better.

GREAT WONDER!!!! THIS HOVERBOARD LEVITATES

2016-01-12T21:13:00.000+01:00

Recently, Lexus introduced a short teaser video for SLIDE, a hoverboard that appears to not just live up to our Back to the Future II dreams but, at least an improve on them. Better yet, it’s more science than science fiction. Here’s how it works. MAGNETS!!! purely magnets
According to Lexus, its hoverboard relies on superconductors and magnets, which combine to repel the force of gravity and lift an object. With a superconductor you don’t need to have an oscillating magnetic field, Instead you have something called the Meissner effect, which essentially says that when you take a magnetic field near the superconductor, it induces current in that superconductor, and creates essentially an image magnetic field on the other side of the superconductor. You create current, but since it’s a superconductor, the currents don’t die away. So you don’t need oscillating magnetic fields. You can have a magnet that levitates above a superconductor or vice versa, a superconductor that levitates above a magnet.
As for the wisps of smoke you see rising from the sides of the Lexus board? That’s not just for effect That’s liquid nitrogen, cooling the superconductors below their transition temperature. The temp at which it becomes superconducting. Just how cold are we talking? -321 degrees Farenheit, says Palm, who also cautions that it’s not quite as extreme as it sounds. “That sounds very cold,” . “but liquid nitrogen is actually a byproduct of the steel industry, so it’s pretty inexpensive.” It’s the same principle as the dry ice you played with in elementary Chemistry, just around three times as cold.
When the liquid nitrogen runs out, the superconductors warm up and the hoverboard stops, well, hovering, until you top it off again.
It will be fun if it's finally mass produced, you know, levitate anywhere, like a witch.

HOVERBOARD!!! Here is who it works

2016-01-11T20:32:00.001+01:00

A Hoverboard has the following main components:

A steel frame with a central pivot
A logic board
Two gyroscopes
Two infrared sensors
Two electric motors (located inside the wheels)
Two tilt/speed sensors (located inside the wheels)
Charging port
Power switch
A battery pack
LED lights
Pressure pads
A plastic shell

Working Principle

The Wheel Sensor
The wheels of the hoverboard house the electric motors themselves. They also contain a tilt and speed sensor. This detects the rpm (revolutions per minute) of the individual wheel, and sends it to the gyroscope and speed control boards, located inside the main body, right next to the wheels.

Gyroscope / Speed Control Boards

The gyroscope and speed control boards receive the rpms and tilt information from the sensor inside the wheels, and they, in turn, send it to the main logic board.
When you calibrate your board, the gyroscopes are basically “zeroed”, as in, you’re telling the gyroscopes, “this is flat, hence this is when the hoverboard’s tilt is at 0”.

The Main Logic Board

The logic board is the “brain” of your hoverboard, and it’s where the processor computes in real time the status of the board, the speed at which you’re travelling, and the relative speed and tilt of the individual wheels (because, for example, when you turn the two wheels have opposing tilts, and hence opposing rpms and motion).
It also controls the power management of the board, and wether you are in “beginner mode” (thereby limiting the max speed of the board) or if the scooter is “locked”.

The Battery Pack

The battery pack is what keeps your board going. There are different packs out there, but the vast majority of them are 36V 4400mAH battery packs.

How does a Hoverboard detect your movement?

This is possibly the most interesting part of the board, the pressure pads sit on two switches each.
When you lean forward, the front switch is pushed down, and a little plastic “wall” slides in-between an infrared LED and an infrared sensor.
As long as the sensor detects the light, the logic board will “tell” the motors to be still. But when the light is interrupted (because of the switch being pushed down by your weight), the board tells the motor to spin in a particular direction.
So, for example, if you’re turning left, your foot activates the front right switch, making the right wheel spin forward, while your left foot activates the back left switch, making the left wheel spin backwards.

So how does a Hoverboard Balance?

The tilt sensors in the wheels tell the gyroscopes how far forward you’re leaning. The gyroscopes relay this information to the logic board.
The more you’re leaning forward, the faster the logic board tells the motors to spin, to sort of “catch up” with your center of gravity. It’s this simple mechanism which allows you to control the cruising speed of the scooter with your weight.
I hope by now you will be able to ride one when you come across it.

You want to get things WET!!! try this

2016-01-10T22:56:00.000+01:00

Most times we need to get a huge ground wet always, or it might be plants, here is a simple way you can handle this

Step 1: Getting started

Decide what you want to be covered by the watering system. Draw a rough plan on paper showing the garden details (position of the house, beds, paths, tap etc) and measurements. You’ll need this to estimate the equipment for the job whether you do it yourself or go to a specialty irrigation shop for advice and service. You should plan on spacing your sprays about 1 metre apart for good coverage.

Step 2: Get your materials

To help you buy the correct fittings the irrigation shop will need your rough plan and the results of a flow test to see how much volume of water is available.
A flow test is simply an estimate of the rate at which water flows out of your tap. To find this information take all fittings (hoses etc) off one of the garden taps and turn it on full force. Place a household bucket underneath the tap and time how long it takes to reach the top of the bucket. This information will help the irrigation specialists determine the correct components for your garden.
When you visit a specialist irrigation shop they will be able to translate your rough plan into a detailed plan and estimate the length of pipe and the number of fittings that you will need.

Step 3: Laying out the system

You will be supplied with a length of black polypipe tubing. This is the main irrigation pipe from which run the sprayers. We selected 19mm width poly pipe, which delivers a good flow of water.
To make placement easier, unroll the pipe (for example on the lawn) and allow it to straighten in the warmth of the sun. This will get rid of all the kinks and curls.
Lay your piping out over the areas which you want to be watered.
Tip: When laying the tubing try to curve it instead of always cutting and joining with T-joints or elbows as you lose about 11% of your water flow with each additional joint.
Cut your pipe to fit the area using sharp secateurs (alternatively use a sharp Stanley or craft knife but take care not to cut yourself) and join with the appropriate joiner and ratchets. Leave one or two ends open to check water flow.
Cover the ends of the plastic tubing with tape or something similar to stop dirt getting into the pipes as they move through the soil.

Step 4:Flow Check

Once the 19mm pipe is laid out across the garden, connect the main tube to your garden tap. It is a good idea to insert an inline filter between the tap and the main tubing to catch anything which may otherwise block the tiny spray heads.
Turn on the tap to check the flow from the unjoined pipes. This will also flush any soil from the pipes which could impede the flow later.
When you have established that water is flowing to all parts of the system, turn off the tap and join the open ends to the appropriate joiner. Placing a ratchet clip over the piping covering the joiner and sealing with a pair of multigrips stops the tubing from coming off later – it’s often difficult to trace a dislodged seal once the pipe is buried, so save yourself some time and trouble by doing it correctly first time round.

Step 5: Selecting the sprayers

There are a number of different spray heads that can be used to cover different shaped garden beds and so avoid wasting water on paths and the like including:
90deg. heads – good for corners.

180deg. spray heads – use to keep spray off the path when aimed towards the bed.
360deg. heads – deliver a circular spray pattern that is ideal for the middle of garden beds.
strip spray heads – to deliver a lengthways band of water for rectangular areas.

Step 6: Installing the risers and spray heads

The sprayers are linked into the main irrigation pipe with narrow tubes or risers (3.9mm), usually called spaghetti tube, which in turn are attached to rigid, plastic stakes known as landscape stakes
Cut the risers to length and attach each piece to a landscape stake and insert a joiner in the end which will be attached to the poly pipe.
Using a hosing clip punch (sold as a punch tool and available from irrigation suppliers), make a hole in the 19mm irrigation pipe at a spot which will be midway between the adjacent plants. Insert one end of the riser tubing to the main pipe and plant the stake in the ground.
Note: The advantage of using risers is that the spray head can be moved around as the plants grow without having to punch more holes in the buried pipe. Fixed risers may have plants grow over the top which will interfere with the spray, so the moveable risers on stakes are more convenient and practical.
Repeat until all risers are in position. If you make a mistake when punching a hole it can be repaired with a seal called a goof plug.
The next step is to attach the appropriate spray head to each riser. You may find it easier to first insert a brass head to cut a thread before inserting the permanent plastic heads.
Tip: Leather gloves will save your hands and give you a better grip when screwing in the spray heads.

Step 7: Finishing touches

Hold down pipe where necessary with wire pegs.
To cover the pipe dig a shallow trench 6-8cm (3-4″) deep, lay pipe in trench and cover.

What You Need To Know About Your Mobile Network

2016-01-09T22:57:00.000+01:00

1G analog
2G digital, voice (GSM)
2.5G added data (GPRS)
2.75G faster data (EDGE)
3G digital, supported data, packet switched (WCDMA)
3.5G faster downlink data (HSDPA)
3.6G faster uplink data (HSPA)
3.75G more enhanced HSPA (HSPA+/eHSPA)
4G wireless broadband

Meaning Of Symbol G In Mobile Signal:

G stands for GPRS (General Packet Radio Service),considered to be the second generation (2G) mobile technology.
It is very slow compared to other technologies and oldest among all mobile technologies.
Maximum download speed = 53.6 kb/s
Maximum upload speed = 28 kb/s
Good for chatting applications like WhatsApp, 2go…. with this internet but not suitable for browsing webpages.
Meaning Of The Symbol E In Mobile Signal:

E stands for EDGE (Enhanced data Rates for GSM Evolution).This technology lies between 2G & 3G. Most blackbery phones carry this.
- EDGE is considered as pre-3G radio technology.
- Maximum download speed = 217.6 kb/s.
- Maximum upload speed = 108 kb/s.
- EDGE is faster than GPRS, suitable for browsing webpages but not for streaming videos/audios.
Meaning Of The Symbol 3G In Mobile Signal:
- 3G stands for UMTS (Universal Mobile Telecomm. System) and short form of Third Generation introduced in 1998.
- It provides mobile broadband access of several MB/s to smartphone and mobile modems in Laptop Computers.
- - Maximum download speed = 384 kb/s.
  - Maximum upload speed = 128 kb/s.
  - 3G is faster than EDGE and users are able to experience faster data transmission speeds. 3G networks allow people to access music, pictures, and videos.
  Meaning Of The Symbol H In Mobile Signal:
  - H stand for HSPA (High Speed Packet Access), considered to be the 3.5 generation mobile technology(Enhanced 3G).
  - HSPA is further divided into HSDPA(download) and HSUPA(upload) to denote download and upload speeds.
  - Maximum download speed = 7.2 MB/s.
  - Maximum upload speed = 3.6 MB/s.
  - You can stream music and even YouTube Videos without much interruption.
    Meaning Of The Symbol H+ In Mobile Signal:
  - H+ stands for Evolved HSPA,the development of technology H.
  - Before the emergence of the 4G,it has been considered as best technology.
  - Maximum download speed = 14~168 MB/s.
  - Maximum upload speed = 5.7~ 23 MB/s.
  - Downloading and buffering can run smoothly.
  Meaning Of The Symbol 4G In Mobile Signal:
- 4G stands for Fourth generation,the development of technology H+ allowing wireless Internet access at a much higher speed.
- It is also called LTE (Long Term Evolution),download files from the Internet up to 10 times faster than 3G.
- Maximum download speed = 100~1000 MB/s.
- Maximum upload speed = 50~ 500 MB/s.
- To download a new game or stream a TV show in HD, you can do it without buffering
I hope when next you are buying a phone you will be able to know the capacity of the network.

ANDROID (operating system)

2012-05-01T21:57:00.001+02:00

Android (operating system) Android Home screen displayed by Samsung Nexus S with Google, running Android 2.3 "Gingerbread" Company / developer Google Inc, Open Handset Alliance Programmed in XML, C (core),[1] Java (UI), C++ Working state Current Source model Mixed (free and open source software and proprietary software)[2][3] Initial release 21 October 2008 Latest stable release Tablets: 3.2 (Honeycomb)[4] Phones: 2.3.5 (Gingerbread) / 25 July 2011; 31 days ago[4] Package manager APK Supported platforms ARM, MIPS,[5] x86[6][citation needed] Kernel type Linux kernel (monolithic) Default user interface Graphical License Apache License 2.0 before 3.0, closed source for 3.0, 3.1 and 3.2: Linux kernel patches under GNU GPL v2[7] Official website http://www.android.com/ History Foundation Android, Inc. was founded in Palo Alto, California, United States in October, 2003 by Andy Rubin (co-founder of Danger),Rich Miner (co-founder of Wildfire Communications, Inc.),Nick Sears (once VP at T-Mobile),and Chris White (headed design and interface development at WebTV)to develop, in Rubin's words "...smarter mobile devices that are more aware of its owner's location and preferences".[27] Despite the obvious past accomplishments of the founders and early employees, Android Inc. operated secretively, revealing only that it was working on software for mobile phones.[27] That same year, Rubin ran out of cash. Steve Perlman brought him $10,000 in cash in an envelope and refused a stake in the company.[28] Acquisition by Google Google acquired Android Inc. in August 2005, making Android Inc. a wholly owned subsidiary of Google Inc. Key employees of Android Inc., including Andy Rubin, Rich Miner and Chris White, stayed at the company after the acquisition.[24] Not much was known about Android Inc. at the time of the acquisition, but many assumed that Google was planning to enter the mobile phone market with this move.[citation needed] Post-acquisition development At Google, the team led by Rubin developed a mobile device platform powered by the Linux kernel. Google marketed the platform to handset makers and carriers on the premise of providing a flexible, upgradable system. Google had lined up a series of hardware component and software partners and signaled to carriers that it was open to various degrees of cooperation on their part.[29][30][31] Speculation about Google's intention to enter the mobile communications market continued to build through December 2006.[32] Reports from the BBC and The Wall Street Journal noted that Google wanted its search and applications on mobile phones and it was working hard to deliver that. Print and online media outlets soon reported rumors that Google was developing a Google-branded handset.[33] Some speculated that as Google was defining technical specifications, it was showing prototypes to cell phone manufacturers and network operators. In September 2007, InformationWeek covered an Evalueserve study reporting that Google had filed several patent applications in the area of mobile telephony.[34][35] [edit] Open Handset Alliance Main article: Open Handset Alliance Today's announcement is more ambitious than any single 'Google Phone' that the press has been speculating about over the past few weeks. Our vision is that the powerful platform we're unveiling will power thousands of different phone models. Eric Schmidt, former Google Chairman/CEO[13] On November 5, 2007, the Open Handset Alliance, a consortium of several companies which include Broadcom Corporation, Google, HTC, Intel, LG, Marvell Technology Group, Motorola, Nvidia, Qualcomm, Samsung Electronics, Sprint Nextel, T-Mobile and Texas Instruments unveiled itself. The goal of the Open Handset Alliance is to develop open standards for mobile devices.[13] On the same day, the Open Handset Alliance also unveiled their first product, Android, a mobile device platform built on the Linux kernel version 2.6.[13] On December 9, 2008, 14 new members joined, including ARM Holdings, Atheros Communications, Asustek Computer Inc, Garmin Ltd, Huawei Technologies, PacketVideo, Softbank, Sony Ericsson, Toshiba Corp, and Vodafone Group Plc.[36][37] [edit] Licensing With the exception of brief update periods, Android has been available under a free and open source software license since October 21, 2008. Google published the entire source code (including network and telephony stacks)[38] under an Apache License.[39] Google also keeps the reviewed issues list publicly open for anyone to see and comment.[40] Even though the software is open-source, device manufacturers cannot use Google's Android trademark unless Google certifies that the device complies with their Compatibility Definition Document (CDD). Devices must also meet this definition to be eligible to license Google's closed-source applications, including the Android Market.[41] In September 2010, Skyhook Wireless filed a lawsuit against Google in which they alleged that Google had used the compatibility document to block Skyhook's mobile positioning service (XPS) from Motorola's Android mobile devices.[42] In December 2010 a judge denied Skyhook's motion for preliminary injunction, saying that Google had not closed off the possibility of accepting a revised version of Skyhook's XPS service, and that Motorola had terminated their contract with Skyhook because Skyhook wanted to disable Google's location data collection functions on Motorola's devices, which would have violated Motorola's obligations to Google and its carriers.[43] In early 2011, Google chose to temporarily withhold the source code to the tablet-only Honeycomb release, which called into question the "open-ness" of this Android release.[44] The reason, according to Andy Rubin in an official Android blog post, was because Honeycomb was rushed for production of the Motorola Xoom,[45] and they did not want third parties creating a "really bad user experience" by attempting to put onto smartphones a version of Android intended for tablets.[46] Google later confirmed that the Honeycomb source code would not be released until after it was merged with the Gingerbread release in Ice Cream Sandwich.[47] Version history Main article: Android version history Android has seen a number of updates since its original release. These updates to the base operating system typically fix bugs and add new features. Generally, each new version of the Android operating system is developed under a code name based on a dessert item. Past updates included Cupcake and Donut. The code names are in alphabetical order (Cupcake, Donut, Eclair, Froyo, Gingerbread, Honeycomb, and the upcoming Ice Cream Sandwich). Below is a list of the most recent versions, and what they include: • 2.0 (Eclair) included a new web browser, with a new user interface and support for HTML5 and the W3C Geolocation API. It also included an enhanced camera app with features like digital zoom, flash, color effects, and more.[48] • 2.1 (Eclair) included support for voice controls throughout the entire OS. It also included a new launcher, with 5 homescreens instead of 3, animated backgrounds, and a button to open the menu (instead of a slider). It also included a new weather app, and improved functionality in the Email and Phonebook apps.[49] • 2.2 (Froyo) introduced speed improvements with JIT optimization and the Chrome V8 JavaScript engine, and added Wi-Fi hotspot tethering and Adobe Flash support[50] • 2.3 (Gingerbread) refined the user interface, improved the soft keyboard and copy/paste features, and added support for Near Field Communication[51] • 3.0 (Honeycomb) was a tablet-oriented[52][53][54] release which supports larger screen devices and introduces many new user interface features, and supports multicore processors and hardware acceleration for graphics.[55] The Honeycomb SDK has been released and the first device featuring this version, the Motorola Xoom tablet, went on sale in February 2011.[56] • 3.1 (Honeycomb) was announced at the 2011 Google I/O on 10 May 2011. - To allow honeycomb devices to directly transfer content from USB devices[57] • 3.2 (Honeycomb) is "an incremental release that adds several new capabilities for users and developers". Highlights include optimization for a broader range of screen sizes; new "zoom-to-fill" screen compatibility mode; capability to load media files directly from the SD card; and an extended screen support API, providing developers with more precise control over the UI.[58] Future releases that have been announced include: • 4.0 (Ice Cream Sandwich)[59] is said to be a combination of Gingerbread and Honeycomb into a "cohesive whole".[60] It will be released in Q4 2011.[61] Design Android's kernel is derived from the Linux kernel. Google contributed code to the Linux kernel as part of their Android effort, but certain features, notably a power management feature called wakelocks, were rejected by mainline kernel developers, so the Android kernel is now a separate version or fork of the Linux kernel.[62][63][64] Google announced in April 2010 that they would hire two employees to work with the Linux kernel community.[65] Greg Kroah-Hartman, the current Linux kernel maintainer for the -stable branch, said in December 2010 that he was concerned that Google was no longer trying to get their code changes included in mainstream Linux.[63] Some Google Android developers hinted that "the Android team was getting fed up with the process", because they were a small team and had more urgent work to do on Android.[66] Android does not have a native X Window System nor does it support the full set of standard GNU libraries, and this makes it difficult to port existing GNU/Linux applications or libraries to Android.[67] However, support for the X Window System is possible.[68] Features The Android Emulator default home screen (v1.5) Architecture diagram Current features and specifications:[69][70][71] Handset layouts The platform is adaptable to larger, VGA, 2D graphics library, 3D graphics library based on OpenGL ES 2.0 specifications, and traditional smartphone layouts. Storage SQLite, a lightweight relational database, is used for data storage purposes. Connectivity Android supports connectivity technologies including GSM/EDGE, IDEN, CDMA, EV-DO, UMTS, Bluetooth, Wi-Fi, LTE, NFC and WiMAX. Messaging SMS and MMS are available forms of messaging, including threaded text messaging and now Android Cloud To Device Messaging Framework(C2DM) is also a part of Android Push Messaging service. Multiple language support Android supports multiple human languages. The number of languages more than doubled for the platform 2.3 Gingerbread. Android lacks font rendering of several languages even after official announcements[citation needed] of added support (e.g. Hindi). Web browser The web browser available in Android is based on the open-source WebKit layout engine, coupled with Chrome's V8 JavaScript engine. The browser scores a 93/100 on the Acid3 Test. Java support While most Android applications are written in Java, there is no Java Virtual Machine in the platform and Java byte code is not executed. Java classes are compiled into Dalvik executables and run on Dalvik, a specialized virtual machine designed specifically for Android and optimized for battery-powered mobile devices with limited memory and CPU. J2ME support can be provided via third-party applications. Media support Android supports the following audio/video/still media formats: WebM, H.263, H.264 (in 3GP or MP4 container), MPEG-4 SP, AMR, AMR-WB (in 3GP container), AAC, HE-AAC (in MP4 or 3GP container), MP3, MIDI, Ogg Vorbis, FLAC, WAV, JPEG, PNG, GIF, BMP.[71] Streaming media support RTP/RTSP streaming (3GPP PSS, ISMA), HTML progressive download (HTML5 tag). Adobe Flash Streaming (RTMP) and HTTP Dynamic Streaming are supported by the Flash plugin.[72] Apple HTTP Live Streaming is supported by RealPlayer for Mobile,[73] and by the operating system in Android 3.0 (Honeycomb).[55] Additional hardware support Android can use video/still cameras, touchscreens, GPS, accelerometers, gyroscopes, magnetometers, dedicated gaming controls, proximity and pressure sensors, thermometers, accelerated 2D bit blits (with hardware orientation, scaling, pixel format conversion) and accelerated 3D graphics. Multi-touch Android has native support for multi-touch which was initially made available in handsets such as the HTC Hero. The feature was originally disabled at the kernel level (possibly to avoid infringing Apple's patents on touch-screen technology at the time).[74] Google has since released an update for the Nexus One and the Motorola Droid which enables multi-touch natively.[75] Bluetooth Supports A2DP, AVRCP, sending files (OPP), accessing the phone book (PBAP), voice dialing and sending contacts between phones. Keyboard, mouse and joystick (HID) support is available through manufacturer customizations and third-party applications. Full HID support is planned for Android 3.0 (Honeycomb).[55] Video calling Android does not support native video calling, but some handsets have a customized version of the operating system that supports it, either via the UMTS network (like the Samsung Galaxy S) or over IP. Video calling through Google Talk is available in Android 2.3.4 and later. Gingerbread allows Nexus S to place Internet calls with a SIP account. This allows for enhanced VoIP dialing to other SIP accounts and even phone numbers. Skype 2.1 offers video calling in Android 2.3, including front camera support. Multitasking Multitasking of applications is available.[76] Voice based features Google search through voice has been available since initial release.[77] Voice actions for calling, texting, navigation, etc. are supported on Android 2.2 onwards.[78] Tethering Android supports tethering, which allows a phone to be used as a wireless/wired Wi-Fi hotspot. Before Android 2.2 this was supported by third-party applications or manufacturer customizations.[79] Screen capture Android does not support screenshot capture as of 2011. This is supported by manufacturer and third-party customizations. Screen Capture is available through a PC connection using the DDMS developer's tool.[80] [edit] Uses Main article: List of Android devices The Android operating system is used on smartphones, netbooks, tablet computers, Google TV, and other devices.[81][82] The main hardware platform for Android is the ARM architecture. There is support for x86 from the Android-x86 project,[83] and Google TV uses a special x86 version of Android. The first commercially available phone to run Android was the HTC Dream, released on 22 October 2008.[84] In early 2010 Google collaborated with HTC to launch its flagship[85] Android device, the Nexus One. This was followed later in 2010 with the Samsung-made Nexus S. iOS and Android 2.3.3 'Gingerbread' may be set up to dual boot on a jailbroken iPhone or iPod Touch with the help of OpeniBoot and iDroid.[86][87] Applications See also: Android software development and List of open source Android applications Applications are usually developed in the Java language using the Android Software Development Kit, but other development tools are available, including a Native Development Kit for applications or extensions in C or C++, and Google App Inventor, a visual environment for novice programmers. Android Market Main article: Android Market Android Market is the online software store developed by Google for Android devices. An application program ("app") called "Market" is preinstalled on most Android devices and allows users to browse and download apps published by third-party developers, hosted on Android Market. As of December 2010 there were about 200,000 games, applications and widgets available on the Android Market.[88] In April 2011 Google said there had been more than 3 billion Android apps installed[89] and at end of June 2011 there are 6 billion apps installs from the Android market. The operating system itself is installed on 130 million total devices.[90] Only devices that comply with Google's compatibility requirements are allowed to preinstall Google's closed-source Android Market app and access the Market.[91] The Market filters the list of applications presented by the Market app to those that are compatible with the user's device, and developers may restrict their applications to particular carriers or countries for business reasons. [92] Google has participated in the Android Market by offering several applications themselves, including Google Voice for the Google Voice service, Sky Map for watching stars, Finance for their finance service, Maps Editor for their MyMaps service, Places Directory for their Local Search, Google Goggles that searches by image, Gesture Search for using finger-written letters and numbers to search the contents of the phone, Google Translate, Google Shopper, Listen for podcasts and My Tracks, a jogging application. In August 2010, Google launched "Voice Actions for Android",[93] which allows users to search, write messages, and initiate calls by voice. Alternatively, users can install apps from third party app stores such as the Amazon Appstore,[94] or directly onto the device if they have the application's APK file. [edit] Marketing The Android logo was designed along with the Droid font family made by Ascender Corporation.[95] Android Green is the color of the Android Robot that represents the Android operating system. The print color is PMS 376C and the RGB color value in hexadecimal is #A4C639, as specified by the Android Brand Guidelines.[96] The custom typeface of Android is called Norad. It is only used in the text logo.[97] [edit] Market share Research company Canalys estimated in Q2 2009 that Android had a 2.8% share of worldwide smartphone shipments.[98] By Q4 2010 this had grown to 33% of the market, becoming the top-selling smartphone platform. This estimate includes the Tapas and OMS variants of Android.[21] In February 2010 ComScore said the Android platform had 9.0% of the U.S. smartphone market, as measured by current mobile subscribers. This figure was up from an earlier estimate of 5.2% in November 2009.[99] By the end of Q3 2010 Android's U.S. market share had grown to 21.4 percent.[100] In May 2010, Android's first quarter U.S. sales surpassed that of the rival iPhone platform. According to a report by the NPD group, Android achieved 25% smartphone sales in the US market, up 8% from the December quarter. In the second quarter, Apple's iOS was up by 11%, indicating that Android is taking market share mainly from RIM, and still has to compete with heavy consumer demand for new competitor offerings.[101] Furthermore, analysts pointed to advantages that Android has as a multi-channel, multi-carrier OS, which allowed it to duplicate the quick success of Microsoft's Windows Mobile.[102] In Q4 2010 Android had 59% of the total installed user base of Apple's iOS in the U.S. and 46% of the total installed user base of iOS in Europe.[103][104] As of June 2011 Google said that 550,000 new Android devices were being activated every day[105]—up from 400,000 per day two months earlier in May 2011, and more than 100 million devices have been activated.[19] Android hit 300,000 activations per day back in December 2010. In July 14, 2011 550,000 Android devices are now activated by Google each day with growth 4.4 percent per week.[106] On the 1st of August 2011 Canalys estimates Android has about 48% of the smartphone market share.[107] Usage share Version Distribution API level 3.x.x Honeycomb 11-13 1.3% 2.3.x Gingerbread 9-10 24.3% 2.2 Froyo 8 55.9% 2.1 Eclair 7 15.2% 1.6 Donut 4 2.0% 1.5 Cupcake 3 1.3% Criticism A concern has been raised that this article's Criticism section may be compromising the article's neutral point of view of the subject. Possible resolutions may be to integrate the material in the section into the article as a whole, or to rewrite the contents of the section. Please see the discussion on the talk page. (August 2011) [edit] Malware and security In August 2010, an SMS Trojan called Trojan-SMS.AndroidOS.FakePlayer.a infected a number of mobile devices, according to security firm Kaspersky Lab. Disguised as a harmless media player application, the trojan, once installed sends out SMS text messages without the user's knowledge or consent. According to Denis Maslennikov, Senior Malware Researcher at Kaspersky Lab, an exact number of devices infected is not available at present, but the outbreak is currently regional. For now, only Russian Android users can actually lose money after installing the Trojan, but anyone can be infected.[108] Android users were advised not to use the Android web browser until Google issues a security patch. The Android Security Team responded and developed a fix on February 5 2011 and patched Open Source Android two days later. In March 2011, Google pulled 58 malicious apps from the Android Market, but not before the 58 apps were downloaded to around 260,000 devices.[109] These apps were malicious applications in the Android Market which contained trojans hidden in pirated versions of legitimate apps.[110] The malware (called DroidDream) exploited a bug which was present in versions of Android older than 2.2.2.[111] Android device manufacturers and carriers work in tandem to distribute Android based updates and had not uniformly issued patches to their customers for the DroidDream exploit, leaving users vulnerable.[112] Google said the exploit allowed the apps to gather device specific information, as well as personal information. The exploit also allowed the apps to download additional code that could be run on the device.[113] Within days, Google remotely wiped the apps from infected users and rolled out an update that would negate the exploits that allowed the apps to view information. They also announced that they would be resolving the issue to ensure that events like this did not occur again.[114] Security firms such as AVG Technologies and Symantec have released "antivirus" software for Android devices. In August 2011, the security firm Lookout estimated that between half a million to one million Android users have been affected by malicious software in the first half of 2011. Lookout also reported that there was an increase of applications infected with malware, from 80 to 400 in the first six months of 2011.[115] Qihoo 360, a Chinese internet security firm, noted in a report that Android is the second largest mobile OS (behind Symbian) to be infected with malware within China. The report stated that Android has become the new "malware hotspot" largely due to the operating system's rise in popularity, and that there were 968 pieces of new malware and trojans targeting Android during the first half of 2011, up from 12 Android-specific threats in 2010.[116] [edit] Privacy It has been reported that Google uses Android smartphones to report the location of Wi-Fi access points it encounters as phone users move around to build vast databases containing physical location of hundreds of millions of such access points. These databases form electronic maps to locate smartphones, allowing them to run apps like Foursquare and companies like Google to deliver location-based ads.[117] One design issue is that average users have no feasible ability to monitor how downloaded applications access and use private and sensitive data (e.g. location and hardware ID numbers). Even during installation, permission checks do not often indicate to the user how critical services and data will be used or misused. To identify how such information may be exfiltrated there is a need for third party monitoring software, such as TaintDroid[118] (an academic research-funded project). Installing such low-level monitoring tools requires programming skills, reflashing the ROM, and voids the warranty.[119] Users can also be notified of an application's behavior via a license agreement that is usually (not always, due to lack of enforcement), displayed on first use of the application but it is generally accepted that majority of the users do not read or understand the legal fine print in license agreements and often just skip and accept them Claimed IP infringement See also: Oracle Corporation#Lawsuit against Google On 12 August 2010, Oracle, owner of Java since it acquired Sun Microsystems in April 2009, sued Google over claimed infringement of copyrights and patents. The lawsuit claims that, "In developing Android, Google knowingly, directly and repeatedly infringed Oracle's Java-related intellectual property".[120] Specifically the patent infringement claim references seven patents including United States Patent No. 5,966,702, entitled "Method And Apparatus For Preprocessing And Packaging Class Files", and United States Patent No. 6,910,205, entitled "Interpreting Functions Utilizing A Hybrid Of Virtual And Native Machine Instructions".[121] It also references United States Patent No. RE38,104, ("the '104 patent") entitled “Method And Apparatus For Resolving Data References In Generated Code” authored by James Gosling, best known as the father of the Java programming language,[122] and currently a Google employee.[123] In response Google submitted multiple lines of defense, saying that Android did not infringe on Oracle's patents or copyright, that Oracle's patents were invalid, and several other defenses. They said that Android is based on Apache Harmony, a clean room implementation of the Java class libraries, and an independently developed virtual machine called Dalvik.[124][125][126] The Free Software Foundation has called this suit a "clear attack against someone's freedom to use, share, modify, and redistribute software".[127] However, the FSF also criticized Google, saying that Google could have avoided the suit by building Android on top of IcedTea, whose GPL license provides some protection against patents, instead of implementing it independently under the Apache License. The FSF wrote "It's sad to see that Google apparently shunned those protections in order to make proprietary software development easier on Android" and remarked that Google had not taken any clear position or action against software patents. In 2010, Microsoft started demanding licensing fees from hardware manufacturers shipping Android, claiming that the operating system infringes on a number of patents owned by Microsoft. Microsoft signed deals with HTC Corporation and others, and filed patent infringement lawsuits against Barnes & Noble andMotorola[128]

diode

2011-04-22T14:05:00.000+02:00

A diode is an electrical device allowing current to move through it in one direction with far greater ease than in the other.In electronics, a diode is a two-terminal electronic component that conducts electric current in only one direction. The term usually refers to a semiconductor diode, the most common type today. This is a crystalline piece of semiconductor material connected to two electrical terminals. A vacuum tube diode (now little used except in some high-power technologies) is a vacuum tube with two electrodes: a plate and a cathode.
The most common function of a diode is to allow an electric current to pass in one direction (called the diode's forward direction), while blocking current in the opposite direction (the reverse direction). Thus, the diode can be thought of as an electronic version of a check valve. This unidirectional behavior is called rectification, and is used to convert alternating current to direct current, and to extract modulation from radio signals in radio receivers.
However, diodes can have more complicated behavior than this simple on-off action. This is due to their complex non-linear electrical characteristics, which can be tailored by varying the construction of their P-N junction. These are exploited in special purpose diodes that perform many different functions. For example, specialized diodes are used to regulate voltage (Zener diodes), to electronically tune radio and TV receivers (varactor diodes), to generate radio frequency oscillations (tunnel diodes), and to produce light (light emitting diodes). Tunnel diodes exhibit negative resistance, which makes them useful in some types of circuits.
CURRENT VOLTAGE CHARACTERISTICS
A semiconductor diode’s behavior in a circuit is given by its current–voltage characteristic, or I–V graph (see graph above). The shape of the curve is determined by the transport of charge carriers through the so-called depletion layer or depletion region that exists at the p-n junction between differing semiconductors. When a p-n junction is first created, conduction band (mobile) electrons from the N-doped region diffuse into the P-doped region where there is a large population of holes (vacant places for electrons) with which the electrons “recombine”. When a mobile electron recombines with a hole, both hole and electron vanish, leaving behind an immobile positively charged donor (dopant) on the N-side and negatively charged acceptor (dopant) on the P-side. The region around the p-n junction becomes depleted of charge carriers and thus behaves as an insulator.
However, the width of the depletion region (called the depletion width) cannot grow without limit. For each electron-hole pair that recombines, a positively charged dopant ion is left behind in the N-doped region, and a negatively charged dopant ion is left behind in the P-doped region. As recombination proceeds more ions are created, an increasing electric field develops through the depletion zone which acts to slow and then finally stop recombination. At this point, there is a “built-in” potential across the depletion zone.
If an external voltage is placed across the diode with the same polarity as the built-in potential, the depletion zone continues to act as an insulator, preventing any significant electric current flow (unless electron/hole pairs are actively being created in the junction by, for instance, light. see photodiode). This is the reverse bias phenomenon. However, if the polarity of the external voltage opposes the built-in potential, recombination can once again proceed, resulting in substantial electric current through the p-n junction (i.e. substantial numbers of electrons and holes recombine at the junction).
At very large reverse bias , beyond the peak inverse voltage or PIV, a process called reverse breakdown occurs which causes a large increase in current (i.e. a large number of electrons and holes are created at, and move away from the pn junction) that usually damages the device permanently. The avalanche diode is deliberately designed for use in the avalanche region. In the zener diode, the concept of PIV is not applicable. A zener diode contains a heavily doped p-n junction allowing electrons to tunnel from the valence band of the p-type material to the conduction band of the n-type material, such that the reverse voltage is “clamped” to a known value (called the zener voltage), and avalanche does not occur. Both devices, however, do have a limit to the maximum current and power in the clamped reverse voltage region. Also, following the end of forward conduction in any diode, there is reverse current for a short time. The device does not attain its full blocking capability until the reverse current ceases.
The second region, at reverse biases more positive than the PIV, has only a very small reverse saturation current. In the reverse bias region for a normal P-N rectifier diode, the current through the device is very low (in the µA range). However, this is temperature dependent, and at sufficiently high temperatures, a substantial amount of reverse current can be observed (mA or more).
The third region is forward but small bias, where only a small forward current is conducted.
As the potential difference is increased above an arbitrarily defined “cut-in voltage” or “on-voltage” or “diode forward voltage drop (Vd)”, the diode current becomes appreciable (the level of current considered “appreciable” and the value of cut-in voltage depends on the application), and the diode presents a very low resistance. The current–voltage curve is exponential.
REVERSE-RECOVERY EFFECT
Following the end of forward conduction in a PN type diode, a reverse current flows for a short time. The device does not attain its full blocking capability until the reverse current ceases.
The effect can be significant when switching large currents very quickly (di/dt on the order of 100 A/µs or more). A certain amount of "reverse recovery time" tr (on the order of tens of nanoseconds) may be required to remove the "reverse recovery charge" Qr (on the order of tens of nanocoulombs) from the diode. During this recovery time, the diode can actually conduct in the reverse direction. In certain real-world cases it can be important to consider the losses incurred by this non-ideal diode effect. However, when the slew rate of the current is not so severe (di/dt on the order of 10 A/µs or less), the effect can be safely ignored.[12] For most applications, the effect is also negligible for Schottky diodes.
The reverse current ceases abruptly when the stored charge is depleted, which is exploited in step recovery diodes for generation of extremely short pulses.
APPLICATIOS
-Radio demodulation
The first use for the diode was the demodulation of amplitude modulated (AM) radio broadcasts. The history of this discovery is treated in depth in the radio article. In summary, an AM signal consists of alternating positive and negative peaks of voltage, whose amplitude or “envelope” is proportional to the original audio signal. The diode (originally a crystal diode) rectifies the AM radio frequency signal, leaving an audio signal which is the original audio signal, minus atmospheric noise. The audio is extracted using a simple filter and fed into an audio amplifier or transducer, which generates sound waves.
-Power conversion
Rectifiers are constructed from diodes, where they are used to convert alternating current (AC) electricity into direct current (DC). Automotive alternators are a common example, where the diode, which rectifies the AC into DC, provides better performance than the commutator of earlier dynamo. Similarly, diodes are also used in Cockcroft–Walton voltage multipliers to convert AC into higher DC voltages.
-Over-voltage protection
Diodes are frequently used to conduct damaging high voltages away from sensitive electronic devices. They are usually reverse-biased (non-conducting) under normal circumstances. When the voltage rises above the normal range, the diodes become forward-biased (conducting). For example, diodes are used in (stepper motor and H-bridge) motor controller and relay circuits to de-energize coils rapidly without the damaging voltage spikes that would otherwise occur. (Any diode used in such an application is called a flyback diode). Many integrated circuits also incorporate diodes on the connection pins to prevent external voltages from damaging their sensitive transistors. Specialized diodes are used to protect from over-voltages at higher power (see Diode types above).
-Logic gates
Diodes can be combined with other components to construct AND and OR logic gates. This is referred to as diode logic.
-Ionizing radiation detectors
In addition to light, mentioned above, semiconductor diodes are sensitive to more energetic radiation. In electronics, cosmic rays and other sources of ionizing radiation cause noise pulses and single and multiple bit errors. This effect is sometimes exploited by particle detectors to detect radiation. A single particle of radiation, with thousands or millions of electron volts of energy, generates many charge carrier pairs, as its energy is deposited in the semiconductor material. If the depletion layer is large enough to catch the whole shower or to stop a heavy particle, a fairly accurate measurement of the particle’s energy can be made, simply by measuring the charge conducted and without the complexity of a magnetic spectrometer or etc. These semiconductor radiation detectors need efficient and uniform charge collection and low leakage current. They are often cooled by liquid nitrogen. For longer range (about a centimetre) particles they need a very large depletion depth and large area. For short range particles, they need any contact or un-depleted semiconductor on at least one surface to be very thin. The back-bias voltages are near breakdown (around a thousand volts per centimetre). Germanium and silicon are common materials. Some of these detectors sense position as well as energy. They have a finite life, especially when detecting heavy particles, because of radiation damage. Silicon and germanium are quite different in their ability to convert gamma rays to electron showers.
Semiconductor detectors for high energy particles are used in large numbers. Because of energy loss fluctuations, accurate measurement of the energy deposited is of less use
-Temperature measurements
A diode can be used as a temperature measuring device, since the forward voltage drop across the diode depends on temperature, as in a Silicon bandgap temperature sensor. From the Shockley ideal diode equation given above, it appears the voltage has a positive temperature coefficient (at a constant current) but depends on doping concentration and operating temperature (Sze 2007). The temperature coefficient can be negative as in typical thermistors or positive for temperature sense diodes down to about 20 kelvins. Typically, silicon diodes have approximately −2 mV/˚C temperature coefficient at room temperature.
-Current steering
Diodes will prevent currents in unintended directions. To supply power to an electrical circuit during a power failure, the circuit can draw current from a battery. An Uninterruptible power supply may use diodes in this way to ensure that current is only drawn from the battery when necessary. Similarly, small boats typically have two circuits each with their own battery/batteries: one used for engine starting; one used for domestics. Normally both are charged from a single alternator, and a heavy duty split charge diode is used to prevent the higher charge battery (typically the engine battery) from discharging through the lower charged battery when the alternator is not running.

Diodes are also used in electronic musical keyboards. To reduce the amount of wiring needed in electronic musical keyboards, these instruments often use keyboard matrix circuits. The keyboard controller scans the rows and columns to determine which note the player has pressed. The problem with matrix circuits is that when several notes are pressed at once, the current can flow backwards through the circuit and trigger "phantom keys" that cause “ghost” notes to play. To avoid triggering unwanted notes, most keyboard matrix circuits have diodes soldered with the switch under each key of the musical keyboard. The same principle is also used for the switch matrix in solid state pinball machines

zener diode.

2011-04-17T20:06:00.000+02:00

A Zener diode is a type of diode that permits current not only in the forward direction like a normal diode, but also in the reverse direction if the voltage is larger than the breakdown voltage known as "Zener knee voltage" or "Zener voltage". The device was named after Clarence Zener, who discovered this electrical property.
A conventional solid-state diode will not allow significant current if it is reverse-biased below its reverse breakdown voltage. When the reverse bias breakdown voltage is exceeded, a conventional diode is subject to high current due to avalanche breakdown. Unless this current is limited by circuitry, the diode will be permanently damaged due to overheating. In case of large forward bias (current in the direction of the arrow), the diode exhibits a voltage drop due to its junction built-in voltage and internal resistance. The amount of the voltage drop depends on the semiconductor material and the doping concentrations.
A Zener diode exhibits almost the same properties, except the device is specially designed so as to have a greatly reduced breakdown voltage, the so-called Zener voltage. By contrast with the conventional device, a reverse-biased Zener diode will exhibit a controlled breakdown and allow the current to keep the voltage across the Zener diode close to the Zener breakdown voltage. For example, a diode with a Zener breakdown voltage of 3.2 V will exhibit a voltage drop of very nearly 3.2 V across a wide range of reverse currents. The Zener diode is therefore ideal for applications such as the generation of a reference voltage (e.g. for an amplifier stage), or as a voltage stabilizer for low-current applications.
Another mechanism that produces a similar effect is the avalanche effect as in the avalanche diode. The two types of diode are in fact constructed the same way and both effects are present in diodes of this type. In silicon diodes up to about 5.6 volts, the Zener effect is the predominant effect and shows a marked negative temperature coefficient. Above 5.6 volts, the avalanche effect becomes predominant and exhibits a positive temperature coefficient.[1] In a 5.6 V diode, the two effects occur together and their temperature coefficients neatly cancel each other out, thus the 5.6 V diode is the component of choice in temperature-critical applications. Modern manufacturing techniques have produced devices with voltages lower than 5.6 V with negligible temperature coefficients, but as higher voltage devices are encountered, the temperature coefficient rises dramatically. A 75 V diode has 10 times the coefficient of a 12 V diode.
All such diodes, regardless of breakdown voltage, are usually marketed under the umbrella term of "Zener diode
Zener diodes are widely used as voltage references and as shunt regulators to regulate the voltage across small circuits. When connected in parallel with a variable voltage source so that it is reverse biased, a Zener diode conducts when the voltage reaches the diode's reverse breakdown voltage. From that point on, the relatively low impedance of the diode keeps the voltage across the diode at that value.
Zener diodes are also used in surge protectors to limit transient voltage spikes.
Another notable application of the zener diode is the use of noise caused by its avalanche breakdown in a random number generator that never repeats
Avalanche breakdown - is a phenomenon that can occur in both insulating and semiconducting materials. It is a form of electric current multiplication that can allow very large currents to flow within materials which are otherwise good insulators. It is a type of electron avalanche. The Avalanche process occurs when the carriers in the transition region are accelerated by the electric field to energies sufficient to free electron-hole pairs via collisions with bond electrons.
Explanation
Materials conduct electricity if they contain mobile charge carriers. There are two types of charge carriers in a semiconductor: free electrons and electron holes. A fixed electron in a reverse-biased diode may break free due to its thermal energy, creating an electron-hole pair. If there is a voltage gradient in the semiconductor, the electron will move towards the positive voltage while the hole will "move" towards the negative voltage. Most of the time, the electron and hole will just move to opposite ends of the crystal and stop. Under the right circumstances, however, (ie. when the voltage is high enough) the free electron may move fast enough to knock other electrons free, creating more free-electron-hole pairs (ie. more charge carriers), increasing the current. Fast-"moving" holes may also result in more electron-hole pairs being formed. In a fraction of a nanosecond, the whole crystal begins to conduct.
Avalanche breakdown usually destroys regular diodes, but avalanche diodes are designed to break down this way at low voltages and can survive the reverse current.
The voltage at which the breakdown occurs is called the breakdown voltage. There is a hysteresis effect; once avalanche breakdown has occurred, the material will continue to conduct if the voltage across it drops below the breakdown voltage. This is different from a Zener diode, which will stop conducting once the reverse voltage drops below the breakdown voltage.

ac circuit part 2

2011-04-12T22:20:00.000+02:00

RL-CIRCUIT
The impedance of an RL circuit is the total opposition to AC current flow caused by the resistor (R) and the reactance of the inductor (XL).
The equation for the impedance of an RL circuit is:

where:
Z = the total impedance in ohms
XL = the inductive reactance in ohms
R = the resistance in ohms
Although you can use an ordinary ohmmeter to measure resistance, there are no common lab instruments for directly measuring reactance and impedance. For all practical purposes, then, you must calculate reactance and impedance from other circuit values that are more readily available.

In practical RL circuits, you can readily determine or directly measure the values of VT, f, R, and L. There is more than enough information among these items to calculate the values of XL and Z.
RC-CIRCUIT
A resistor–capacitor circuit (RC circuit), or RC filter or RC network, is an electric circuit composed of resistors and capacitors driven by a voltage or current source. A first order RC circuit is composed of one resistor and one capacitor and is the simplest type of RC circuit.
RC circuits can be used to filter a signal by blocking certain frequencies and passing others. The four most common RC filters are the high-pass filter, loSeries RLC Circuit
If an AC emf given by is used to drive current through a resistor, a capacitor, and an inductor connected in series, then the current through each element must be the same. The voltages across the various elements obey the rules given above, and the sum of these voltages must, by the loop theorem, be equal to the applied emf. This sum must be taken at a particular instant of time, which is complicated because each voltage difference will be at a different part of its cycle.

Note that the amplitude of I is given by , which looks about like the DC relation I = V / R. The quantity Z is called the impedance, it has units of ohms, and it plays the same role in AC circuits as resistance does in DC circuits. Unlike the resistance, however, it depends on the driving frequency, so the current that flows in the circuit depends sensitively on the driving frequency. Be careful, however; this formula for the impedance only applies to the series RLC circuit. Each different circuit has its own impedance formula.
Resonance: Consider the series RLC circuit discussed above. The formula for the current makes it easy to see how things should be adjusted to get as much current as possible from a given driving emf : simply make Z as small as possible. If the circuit value of R is fixed (as is usually the case) then the only way to get more current is by fiddling with and . And it is clear that the smallest value of Z will be obtained when , which a little algebra shows is equivalent to . But this simply says that things should be adjusted so that the driving frequency is equal to the natural frequency of the circuit (without the correction due to resistance). So, if the driving frequency is near the natural frequency, very large currents can result. When a circuit is driven near its natural frequency, we say that it is being driven at resonance. And the formula for Z shows that the smaller the resistance of the circuit, the larger the response at resonance will be. This is what makes the radio tuner work. The antenna of the radio picks up radio signals from every station in the area, but only the station whose frequency matches the natural frequency of the tuning circuit will cause large currents to flow in the circuit. These currents, when amplified, are the ones that produce the sound you hear. If the circuit is not properly tuned, then it may pick up two stations equally well, an effect you have probably heard many times.
w-pass filter, band-pass filter, and band-stop filter.

simple a.c circuit, part 1

2011-04-12T17:38:00.000+02:00

When an alternator produces AC voltage, the voltage switches polarity over time, but does so in a very particular manner. When graphed over time, the “wave” traced by this voltage of alternating polarity from an alternator takes on a distinct shape, known as a sine wave.
In the voltage plot from an electromechanical alternator, the change from one polarity to the other is a smooth one, the voltage level changing most rapidly at the zero (“crossover”) point and most slowly at its peak. If we were to graph the trigonometric function of “sine” over a horizontal range of 0 to 360 degrees, we would find the exact same pattern.
The reason why an electromechanical alternator outputs sine-wave AC is due to the physics of its operation. The voltage produced by the stationary coils by the motion of the rotating magnet is proportional to the rate at which the magnetic flux is changing perpendicular to the coils (Faraday's Law of Electromagnetic Induction). That rate is greatest when the magnet poles are closest to the coils, and least when the magnet poles are furthest away from the coils. Mathematically, the rate of magnetic flux change due to a rotating magnet follows that of a sine function, so the voltage produced by the coils follows that same function.
A more popular measure for describing the alternating rate of an AC voltage or current wave than period is the rate of that back-and-forth oscillation. This is called frequency. The modern unit for frequency is the Hertz (abbreviated Hz), which represents the number of wave cycles completed during one second of time. In the United States of America, the standard power-line frequency is 60 Hz, meaning that the AC voltage oscillates at a rate of 60 complete back-and-forth cycles every second. In Europe, where the power system frequency is 50 Hz, the AC voltage only completes 50 cycles every second. A radio station transmitter broadcasting at a frequency of 100 MHz generates an AC voltage oscillating at a rate of 100 million cycles every second.
An instrument called an oscilloscope, Figure below, is used to display a changing voltage over time on a graphical screen.
watch out for the next issue.

THE HISTORY OF CHEMICAL ENGINEERING

2011-04-09T01:07:00.001+02:00

THE HISTORY OF CHEMICAL ENGINEERING
Chemical engineering as a profession was established over 100 years when it arose from the combination of mechanical engineering and chemistry1. In the developing chemical industry in the late 19th century there was a critical need for engineers involved in the design, construction, and operation of chemical factories to have a solid understanding of both engineering and chemical principles, particularly chemical reaction stoichiometry and kinetics. The first degrees in chemical engineering in the USA were awarded at that time and the American Institute of Chemical Engineers was established in 1908.

Throughout the 20th century, the profession of chemical engineering developed as the chemical and petrochemical industries2, 3 expanded and as more universities developed formalized chemical engineering curricula that incorporated solid fundamental education in the physical and chemical sciences. As the educational component of chemical engineering developed to include deep fundamental analysis of physical and physical chemical processes, particularly after the 2nd World War with the study of mass, momentum, and energy transport4, 5, the role of chemical engineers in industry and society broaden considerably6.

Because of the emphasis on fundamental principles in the education as opposed to the equipment-specific emphasis of the earlier years, chemical engineering employment diversified into new fields such as microelectronics processing and environmental engineering and pollution control7. The solid fundamental training of chemical engineers in the analysis of complex multiphase systems with chemical reactions and molecular transport was recognized in many industries and government laboratories. Today, the education of modern chemical engineers includes the full range of fundamental subjects in chemistry, physics, and engineering sciences such as thermodynamics, mechanics, fluid mechanics, heat and mass transport, and chemical reactor design. Understanding of these subjects, coupled with the capability to utilize advanced computational methods to solve systems of partial differential equations that describe how materials behave under a very large range of conditions, provide the modern chemical engineer the ability and skills to tackle many problems to improve our modern way of life.
In Nigeria, it started at obafemi awolowo university as department of chemical technology in1969. It became a constituent of chemical technology on the first of October 1971. In 1972 the name was changed to department of chemical engineering, the first set of students graduated 1973.
The post graduate program started in1980 and was developed to provide advance training in industrial development of the country.

Chemical engineers

2011-04-09T00:41:00.000+02:00

The Role of Chemical Engineers
Chemical engineers are considered to be "universal engineers." They use chemistry, physics, biology, microbiology, biochemistry and mathematics to design programs, machines and processes that turn raw materials into valuable products for human use and for use in the environment. Chemical engineers play a very important role in making modern society as we know it from creating simple products such as paper, plastic, rubber, pharmaceuticals, gasoline and cement.
Responsibilities and Duties
Chemical engineers have multiple job responsibilities and duties to perform on a daily basis. Meticulous research is an important first step in order to cover all issues before the production of products. Chemical engineers
are also responsible for designing programs, machinery and processes that are used to manufacture their products. Performing a multitude of tests and analyzing data, problems and engineering design during the creation process is also key work of the chemical engineer. In addition, chemical engineers must prepare multiple reports and consult with other individuals on their findings.
The role that a chemical engineer plays in today’s world is an important one to put it quite simply. There are many responsibilities which a chemical engineer must undertake on a daily basis and various specific duties which must be carried out as well. It is important to look at these items to determine why the role of chemical engineer is so important and whether one is suited for a job of this type.
Specific Duties of a Chemical Engineer
Beneath all of the general responsibilities listed above, a chemical engineer must engage in numerous specific duties on a daily basis. The first duty which the chemical engineer is responsible for completing is research. The chemical engineer must take careful steps to ensure that what they are looking to manufacture and how they are looking to manufacture a product is the right avenue to pursue. The way to resolve this issue is by doing a lot of research on a variety of topics relating to chemical engineering.

The chemical engineer is also responsible for designing a variety of items and this is a very important duty which they must complete. A chemical engineer must design various items such as measurement and control systems, chemical manufacturing equipment and chemical manufacturing processes. This is a major duty on the part of the chemical engineer and one which must be carried out with preciseness at all levels and stages.

A chemical engineer must also engage in a wide array of analyses. The things which the chemical engineer must analyze include test data, engineering design, design problems and research findings. The chemical engineer must take painstaking measures to adequately analyze these items as the outcome of the project could very well depend on the analysis which is undertaken by the chemical engineer.

One who is an engineer must develop certain procedures and policies as well so that there will be smooth operations all the way around the board. Various procedures and policies such as safety procedures, data tables and employment policies may all be in the hands of the chemical engineer. A senior level chemical engineer will have more to do with regard to developing policies and procedures within the company or corporation.

The preparation of multiple reports is also in the hands of the chemical engineer. The chemical engineer must prepare data which specifically details the findings of certain tests and evaluations. These reports can be text or tables depending on the type of report which is needed.

A chemical engineer will also deal with other individuals a great deal. The reason for doing so is to relay the results and findings as well as oversee other chemical engineers and related workers in their field. From time to time, chemical engineers must lecture to their peers and the general public regarding their job and role in society.

All About Technology

ENERGY

ENERGY

FORMS OF ENERGY

POTENTIAL ENERGY

CHEMICAL ENERGY

NUCLEAR ENERGY

GRAVITATIONAL ENERGY

KINETIC ENERGY

ELECTRICAL ENERGY

THERMAL OR HEAT ENERGY

SOUND ENERGY

SOURCES OF ENERGY

NONRENEWABLE ENERGY

RENEWABLE ENERGY

3D Printing

Processes and mechanisms

Examples & applications of 3D printing

OCULUS......How it Works

Technical Specifications

System Requirements

Sources

Soccer Boots; The Shoe Lace Effect

History

Features

Evaluation

Great News

BITCOIN!!! what you need to know about it

For new users

Balances - block chain

Transactions - private keys

Processing - mining

Navigating through your computer easily....try this!!

NEVER GIVE HACKERS THE CHANCE TO MESS THINGS UP

1. Don't be a fool

(adsbygoogle = window.adsbygoogle || []).push({}); 2. Always use a strong password

3. Mind the transactions you carry out on social networks

4. Use different emails

5. Cautions

Phone Camera: More Megapixels isn't always better

sensor

Image processor

The user

GREAT WONDER!!!! THIS HOVERBOARD LEVITATES

HOVERBOARD!!! Here is who it works

Working Principle

Gyroscope / Speed Control Boards

The Main Logic Board

The Battery Pack

How does a Hoverboard detect your movement?

So how does a Hoverboard Balance?

You want to get things WET!!! try this

Step 1: Getting started

Step 2: Get your materials

Step 3: Laying out the system

Step 4:Flow Check

Step 5: Selecting the sprayers

Step 6: Installing the risers and spray heads

Step 7: Finishing touches

What You Need To Know About Your Mobile Network

ANDROID (operating system)

diode

zener diode.

ac circuit part 2

simple a.c circuit, part 1

THE HISTORY OF CHEMICAL ENGINEERING

Chemical engineers

2. Always use a strong password