Suppose the random variable distribution of a random variable X is as follows:

X = xi	P(x = xi)
x1 x2 x3 . . . xn	P1 P2 P3 . . . Pn

Then,
Arithmetic Mean μ =

Variance σ² =

Standard Deviation σ =

Continue Reading >>Arithmetic Mean, Variance and Standard Deviation of a Random Variable Distribution

Data recovery is the last thing on our minds when we are busy.

Data Recovery Equipment

We’ve all been there. Despite knowing that we need to save our work at regular intervals and back everything up, there is always going to be that time when you’re engrossed in what you’re doing and have ploughed on regardless with that complex spreadsheet, calculations or report. You’ve almost finished, 5 o’clock is in sight, and backing up or saving your data is the last thing on your mind. But you can guarantee that will be exactly the moment when you have a power cut. And suddenly the screen is blank and everything has gone.

Even when you have been as careful as can be and saved every last meg on your external hard drive, you can never guarantee that your dog won’t decide to make a tasty meal out of it and have a good old chew.

Well breathe a sigh of relief as this no longer means the loss of all your hard work. Thankfully there are now expert data recovery organisations out there who can not only retrieve data you thought that you had lost, but can offer you a wealth of information and advice about how to stop it happening again. Both the emergency services and the GP of data recovery all-in-one.

These guys can also advise you on which of the wide range of data recovery systems and equipment are the best value for money and meet your individual needs.

Unfortunately they weren’t able to advise on how to tempt my dog into eating dog food instead of electrical equipment.

Continue Reading >>Losing Data is No Longer the End of the World

As you may already know Photokina 2010 has started yesterday September 21 and will last till 26. It is the world's leading fair for photography and imaging industries held at Cologne Trade Fair, Germany every 2 years where new products, trends and the world’s leading brands encounter an unparalleled event line-up.

When talking of world’s leading brands in photography and imaging, Epson would definitely be one of the major players and apparently there is some good news from Epson this morning. Epson have launched the Stylus Pro 4900 – a compact, 17-inch production printer setting new standards in colour precision for the photography and fine art market.

Epson Stylus Pro 4900 offers professional photographers a super-wide colour gamut on the market, and so getting exceptional photographs and fine art images with Epson Stylus Pro 4900 having colours on the print identical to that of the original image is easy.

The all new Stylus Pro 4900 printer boasts outstanding colour consistency, accurate colour matching, and can reproduce 98 percent of all PANTONE colours. Perfect for the small office or photo enthusiasts in studio environment, the Stylus Pro 4900 gives every print a professional finish on a wide range of different media.

Martin Johns, market development manager for large format printers at Epson UK, says:

“Offering photographers outstanding flexibility, the Epson Stylus Pro 4900 creates better-than-lab-quality prints on a wide range of media up to 1.5mm thick, including 330gsm Traditional Photo media presentation matte board, canvas and fine art paper. Users can select a paper path that best fits their needs from a choice of cassette, top and front manual board feed or roll.”

Key Features of the Stylus Pro 4900 include:

• 11-colour UltraChrome HDR ink set
• Reliable Advanced-TFP print head
• 98% PANTONE coverage
• Has got black ink switching at last and so now there is automatic switching possible between photo and matte black inks, which are pre-installed.
• Print speed of 46m² per hour
• Print on media up to 1.5mm thick
• Automatic switching between cut sheet and roll paper

The Epson Stylus Pro 4900 is priced at £2295 (~ Rs. 1, 70,000 across India)

Continue Reading >>Epson Launches New Stylus Pro 4900 - For the Photography and Fine Art Market

Inverse of a Matrix

Suppose A is a given matrix. If there exists a matrix B such that, AB = I = BI then A is said to be an invertible matrix and B is called as inverse of A and is denoted by

Note:- If a matrix A posses an inverse then A is a square matrix and inverse of A is unique.
Proof:-
Since A is invertible there exists a matrix B such that AB = I = BI.
Since AB = BA, A is necessarily a square matrix.
If possible suppose C is also inverse of A which implies AC = I = CA
B = B. I = B (AC) = (BA)C = I.C = C

Therefore If any matrix posses an inverse then it has to be unique.

Continue Reading >>Inverse of a Matrix

Adjoint of a Matrix

If A is a square matrix then the transpose of a matrix obtained by replacing the elements of A by their co-factors is called the adjoint of a matrix A and is denoted by Adj A. For example,

Note

1. 


2. If A is a square matrix of order '3' and K is any scalar then Adj (KA) = K^2 Adj A
   

   Proof :-

   
   Likewise, If A is square matrix of order 'n' then Adjoint of KA = K to the power of (n-1) times Adjoint of A

Continue Reading >>Define Adjoint of a Matrix

Potentiometer

A potentiometer is a electrical device used to measure unknown voltage by comparing it with a known voltage. It comprises of a slide wire of uniform cross-section and hence uniform resistance along its length. A calibrated scaling cm and fraction of cm is placed along the slide wire.

Before using the potentiometer it should be standardized. It is the process of adjusting working current so as to match the voltage drop across a portion of sliding wire against standard cell, whose voltage is constant at 1.0186 Volts at all times. The purpose of this standardization is to make the potentiometer "direct reading".

Standardization of a potentiometer is done by connecting a standard-cell to the terminals marked "Standard-Cell", Galvanometer and Battery to their respective terminals. Potential dials are set to the effective voltage of the standard cell. Now by pressing "Standardize" key and adjusting battery Rheostats (coarse and fine) balance is obtained. The galvanometer should show no deflection with standardized key pressed and zero series resistance. Then the potentiometer is said to be "standardized".

After standardization unknown voltage is applied to the potentiometer. By adjusting the dial resistor and slide-wire, "null" balance is obtained. Under balanced conditions, the readings of slide-wire and dial resistor together gives the value of unknown voltage.

Continue Reading >>What is a Potentiometer

As the saying in English goes: "Familiarity Breeds Contempt", the new is always a wonder, the old detestable and generally people are attracted by the new especially, new website designs, new features and the like. Twitter seems to follow the same mantra as it recently launched a new, re-engineered Twitter.com that provides an easier, faster, and richer experience making the whole twitter activity a lot more fun and as easy as ABC.

The new Twitter design that uses some cutting-edge web technology aims to provide tweeple a faster and richer experience directly inside their browser, without the necessity to use fancy software interfaces like a Tweetdeck or Seesmic. Some of the useful enhancements you can find on the new Twitter include:

• New Two-Panel Design with cleaner timeline on the left and a rich details pane on the right.
  
  
  On the left of the screen, you can find @mentions, retweets, searches, and lists just above your timeline and on the right, you can see features like whom you recently followed, who recently followed you, favorites, and Trending Topics. One feature that takes away a lot of burden is the infinite scroll of your timeline using which you no longer have to click "more" to view additional Tweets.


• Media support that makes it very easy to view embedded photos, videos, and other media content directly on Twitter.


• Details pane showing related content such as @replies, other Tweets by that user, a map of where a geotagged Tweet was sent from, and more just by clicking on a tweet in your timeline.
  


• Keyboard Shortcuts for easy navigation and access to various actions like RT, DM, new tweet etc.
  
  


• Mini Profiles shown without navigating from the page when you click a @username which provides easy access to account information, including bio and recent Tweets by that user.
  

As the updated version of Twitter.com went live just a few day back rolling out to very small percentage of registered accounts, you might not got it for your account yet. If so don't worry, you'll be getting it soon, in a week or two at the most.

Not on Twitter yet?

Twitter is the best way to discover what’s new in your world and stay connected with friends and followers.
Go sign up @ Twitter.com, it won't hurt a bit!
You're Always Welcome to Follow me @ramaraobobby

Continue Reading >>Get Easier Faster and Richer Experience with New Twitter

Our aim here is to determing the value of the unknown electrical capacitance and dissipation factor of a given capacitor by the Schering's bridge.

The circuit diagram of the schering's bridge is as shown in the figure below:

Its connection diagram in the kit is as below:

Determination of "C" :-

The unknown capacitor C and the unknown resistor R can be found in the equipment. When the bridge is balanced, the following equation is satisfied.

Equating the real and imaginary parts on either sides of the equation we get,

Determination of Dissipation Factor :-

A practical capacitor can be considered as a pure capacitor in series with a small resistance as shown below:

The phasor diagram is as below:

Dissipation Factor (D.F) = Power factor of capacitor.

Procedure for Finding Capacitance :-

1. Make connections as shown in the figure. Connect the unknown capacitor using 0.01μFm
2. Set C2 = 0 and R = 0
3. Set R1 = 1000Ω and adjust R2. Adjust both R1 and R2 till you get zero or minimum sound in the headphones.
4. Note down R1, R2, C1 values.
5. Calculate C using the formula C = (C1 R2) / R1
6. Choose different unknown capacitor, repeat the above procedure and find the value of C using equation for C given above.

Procedure for Finding Dissipation Factor (D.F) :-

1. Without disturbing the setting of the bridge (null points with R1 and R2) introduce R with a initial value say of 500Ω
2. Adjust C2 till you get balance as indicated by minimum or zero sound in the headphones
3. Find D.F using the formula D.F = ω.R.C
4. Repeat above steps with different values of R.

Other Main Applications of Schering's Bridge:-

Various other applications of Schering's bridge include measurements of the properties of insulators, capacitor brushings, insulating oil and other insulating materials.

Continue Reading >>Finding Value of Capcitance and Dissipation Factor of a Given Capacitor by Schering Bridge

Whenever you are on a vacation having special time with family and friends you enter into a space which you haven't already experienced like natural places, forests, hills, tourist destinations etc., and it gives you a chance to respond spontaneously keeping you alive and actively use the innate energy. This is where you can experience your best moments bringing life to your years and feel the fulfillment.

As you know everything in life is memory whether good or bad. Attaching and sharing your good memories that made you feel amazing freedom is the key to happiness and that is what makes you feel the fulfillment in life. Needless to say one of the best ways to attach to your good old memories is send those pictures right to your KODAK PULSE 7-inch Digital Frame featuring KODAK Color Science and LED backlighting that can displays your pictures beautifully in 7 inch frame where they look amazing in high-quality digital photo display (800 × 600 pixels).

KODAK PULSE Digital Frame is bundled with wonderful features and functionalities like:

• Built-in Wi-Fi capability that lets users to wirelessly add or replace pictures to the frame from PC, Facebook and KODAK Gallery sites.


• 512MB internal memory that can store up to 4,000 pictures


• No software to install which makes the set-up very easy


• Programmable timer feature to automatically shuts down power at preferred times


• Compatible with 802.11b/g or b/g/n router


• 2 Gigabyte SD Secure Digital Memory Card


• Create your own e-mail address for the frame to easily receive new pictures


• Pictures are automatically resized to fit more on the frame and still look beautiful


• Sharing on-the-go is made easy as you can E-mail pictures from mobile phones


• View pictures right away from memory card or USB drive


• The PULSE automatically links to albums on FACEBOOK and KODAK Gallery sites, so you can see new pictures on your frame as soon as they’re posted.

Whereas taking photographs and sharing your KODAK moments is just a click away with Kodak EasyShare M580 14MP Digital Camera featuring share button and Share button app that makes sharing your pictures on YouTube, Facebook, Flicker and KODAK Gallery sites, plus e-mail too amazingly simple.

• Snap your photographs.
• Press the Share button and tag the pictures to YouTube, Facebook, Flickr and KODAK Gallery sites, plus e-mail too!
• Connect your camera to your computer with Kodak’s Share button app installed and your pictures automatically get transferred to your computer and gets uploaded to your chosen sites.

Kodak EasyShare M580 comes with other wonderful tech features and specifications like:

• The 8X SCHNEIDER-KREUZNACH Optical Zoom Lens, 5X advanced digital zoom
• 28mm Wide-Angle Lens
• 3.0 inch Color Display
• Digital zoom during HD video capture (720p @ 30fps)
• Image stabilization that minimizes blur and the effects of camera shake to deliver clearer, sharper pictures.
• Face Recognition feature that automatically recognizes up to 20 pre-tagged faces and up to five faces in a single image.
• Creative multimedia slideshow of your pictures
• 64 MB in-built memory and SD/SDHC card expansion slot
• Kodak EasyShare Software for transferring, online sharing, e-mailing, organizing, editing, and creative printing of your pictures.

All in all Kodak EasyShare M580 Digital Camera and Kodak Pulse 7-inch Digital Frame is a wonderful combination for capturing, recalling and sharing all the best moments of your life. Go for it and you'll never regret that decision.

Continue Reading >>Turn Moments into Memories with Kodak EasyShare M580 Digital Camera and Kodak Pulse 7-inch Digital Frame

Virender Sehwag is no doubt one of the leading opening batsmen in the world cricket now for his aggresive, adventurous and attacking style of batting. Affectionately known as Viru, this Nawab of Najafgarh is one of three batsmen in the world to have ever surpassed 300 twice in Test cricket and for his excellent performance in all forms of the game he was honored as the Wisden Leading Cricketer in the World consecutively for the years 2008 & 2009.

Virender Sehwag has recently created his Facebook fanpage and true to his fame, more than 390,000 people have liked it already and still counting. As making an live event is the best way to connect with fans all over the world, Viru is coming LIVE on Facebook for an exclusive Chat Event on Thursday, 9th September, 2010 at 9 PM (India). It is like a live chat interview between Viru and his fans where he'll be answering all the interesting Q's during the event.

To participate in this LIVE chat all you have to do is - go to Virender Sehwag Facebook Page (www.facebook.com/virendersehwagofficial) on 9-9-9 and click on 'LIVE Chat' tab.
You can leave your questions or messages for LIVE chat on Sehwag's YouTube Channel, mention @virendersehwag on twitter, or directly post them on the Live Chat Page on Facebook

Posting your questions and messages directly on Facebook would be tad better as you can easily update your status about this live event and it will be shared not only with everyone watching this event but also with your friends as your status on Facebook.com gets updated. So, this seems to be the best way to share in your opinions to broader audience including your friends and everyone else who is involved with this live event.

If you are a die-hard fan of Sehwag, the dashing, calm and one of the focused Indian cricketers, do attend this Live Chat Event!

Where: On Facebook, on the Sehwag Fan Page

When: Thursday, 9th September, 2010, 9:00pm - 10:00pm (India)

If you wish to RSPV click here

Continue Reading >>Chat LIVE with Virender Sehwag on Facebook

With a plethora of bidding sites emerging these days, online users are getting more and more interested in bidding and winning products at unbelievably low prices.BuyAlmost is also one such online auction based shopping portal from India that offers brand new products in various categories at unbelievable discount prices.

BuyAlmost is definitely a great place to win products at amazing low prices as winners of auctions can typically save between 95 to 99 percent off the retail price.

Th Product Categories Include:

• Watches & Jewelery


• iPod, MP3 & Audio


• Cell Phones & Telephone


• PC & Accessories


• Laptops & Notebooks and more...

Go get started @ BuyAlmost

• First Register for Free
• Choose a Bid Pack you wanna buy.
  Mind you, Bigger the pack, cheaper the price per bid.
• Then Place your Bids on the auction of your choice. Each Bid increases the price by 10 Paisa and time by 15 sec.
• The bidder who keeps on bidding until the timer becomes 0 i.e., the last bidder will be declared as the winner for that auction. And as an appreciation of the winner's persistence, all his bids are refunded (upto a maximum of 200 bids) creating a win-win situation.

Free shipping of won products to any part of India and other exciting features like BidBuddy, Hindi version of the site etc., just adds to the fun :)

Continue Reading >>Bid and Win Popular Brands in Electronics-Gadgets and More at Unbelievable Discounts @ BuyAlmost

Launched in November 2009, Formspring.me is the fastest growing social Q&A website which is all about expressing yourself and learning more about the people you care about.

Just like in an ongoing interview, @Formspring.me you can ask questions and give answers, about anything and everything. Formspring is quickly gaining fans all over the world and now there are around 14 million registered members answering millions of questions every day.

The feature on Formspring that is turned down by many as it can exploited to ask bad and mean questions is asking questions anonymously. To fix this, from your account Privacy Settings you can select whether or not you want to receive anonymous questions.

Whether asked anonymously or openly, you'll get a notice of all the questions asked and you can decide whether or not to answer them. As there is no character limit, you are free to post answers that are just a word long to few paragraphs if you want to. If you didn't like any of the questions you're asked, you can delete the question or even block the user. Besides asking questions and answering them, you can also anonymously follow any Formspring member whom you would like to learn more about and by doing that their answers will show up in your home page.

As part of their ongoing efforts to make sharing easier, Formspring has recently launched "Ask your Friends" feature using which in one step you can ask the same question to multiple friends on Formspring, or your friends and followers on other networks. All you have to do is just write your question and select whom you want to send it to.

Also formspring.me is well integrated with Twitter, Facebook, Tumblr, Blogger, MySpace and WordPress sites and blogs.

So, you can easily publish and share your answers on any of these sites and can also link up your account with them, so that more of your friends and contacts can ask you questions or learn more about you.

This No.1 Q&A website is also offering widgets of different sizes that you can easily embed in your blog or website and get questions directly from your blog visitors. Here is the example of Large(400x275) widget of my Formspring which you can use to ask me anything.

Continue Reading >>@Formspring.me You Can Ask Questions, Give Answers and Learn More About Your Friends