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#1 Jokes » Bird Jokes - 2 » Today 01:08:45

ganesh
Replies: 0

Q: How do blue jays stay fit?
A: Wormups.
* * *
Q: What language do geese speak?
A: Porchageese.
* * *
Q: What do you call a bird with a black belt?
A: Steven Seagull.
* * *
Q: Why did the pelican get kicked out of the restaurant?
A: Because he had a very big bill.
* * *
Q: How do you get a raven to stop calling?
A: Take away its cell phone?
* * *
Q: What's the difference between bird flu and swine flu?
A: If you have bird flu, you need tweetment. If you have swine flu, you need oink-ment.
* * *
Q: What do you get when you cross a canary and a lawnmower?
A: Shredded tweet.
* * *
Q:  What did the maple tree say to the woodpecker?
A: Leaf me alone!
* * *

#2 Re: Ganesh's Puzzles » English language puzzles » Today 00:53:15

Hi,

#3257. What does the verb (used with object) dignify mean?

#3258. What does the noun dignitary mean?

#3 Re: Ganesh's Puzzles » Oral puzzles » Today 00:42:31

Hi,

.

#4507. 'A' is thrice as good a workman as 'B', therefore able to finish a job is 60 days less than 'B'. Working together, in how many days will they do it?

#5 Re: Dark Discussions at Cafe Infinity » crème de la crème » Today 00:11:42

533) Cecilia Payne-Gaposchkin

Cecilia Payne-Gaposchkin, original name in full Cecilia Helena Payne, (born May 10, 1900, Wendover, Eng.—died Dec. 7, 1979, Cambridge, Mass., U.S.), British-born American astronomer who discovered that stars are made mainly of hydrogen and helium and established that stars could be classified according to their temperatures.

Payne entered the University of Cambridge in 1919. A lecture by astronomer Sir Arthur Eddington on his expedition to the island of Principe that confirmed Einstein’s theory of general relativity inspired her to become an astronomer. Eddington encouraged her ambition, but she felt there were more opportunities for a woman to work in astronomy in the United States than in Britain. In 1923 she received a fellowship to study at the Harvard College Observatory in Cambridge, Mass., after a correspondence with its director, Harlow Shapley.

Beginning in the 1880s, astronomers at Harvard College such as Edward Pickering, Annie Jump Cannon, Williamina Fleming, and Antonia Maury had succeeded in classifying stars according to their spectra into seven types: O, B, A, F, G, K, and M. It was believed that this sequence corresponded to the surface temperature of the stars, with O being the hottest and M the coolest. In her Ph.D. thesis (published as ‘Stellar Atmospheres’ [1925]), Payne used the spectral lines of many different elements and the work of Indian astrophysicist Meghnad Saha, who had discovered an equation relating the ionization states of an element in a star to the temperature to definitively establish that the spectral sequence did correspond to quantifiable stellar temperatures. Payne also determined that stars are composed mostly of hydrogen and helium. However, she was dissuaded from this conclusion by astronomer Henry Norris Russell, who thought that stars would have the same composition as Earth. (Russell conceded in 1929 that Payne was correct.) Payne received the first Ph.D. in astronomy from Radcliffe College for her thesis, since Harvard did not grant doctoral degrees to women. Astronomers Otto Struve and Velta Zebergs later called her thesis “undoubtedly the most brilliant Ph.D. thesis ever written in astronomy.”

Payne remained at Harvard as a technical assistant to Shapley after completing her doctorate. Shapley had her discontinue her work with stellar spectra and encouraged her instead to work on photometry of stars by using photographic plates, even though more accurate brightness measurements could be made by using recently introduced photoelectric instruments. Payne later wrote, “I wasted much time on this account.…My change in field made the end of the decade a sad one.” During this period, however, Payne was able to continue her stellar spectral work with a second book, ‘Stars of High Luminosity’ (1930), which paid particular attention to Cepheid variables and marked the beginning of her interest in variable stars and novae.

In 1933 Payne traveled to Europe to meet Russian astronomer Boris Gerasimovich, who had previously worked at the Harvard College Observatory and with whom she planned to write a book about variable stars. In Göttingen, Ger., she met Sergey Gaposchkin, a Russian astronomer who could not return to the Soviet Union because of his politics. Payne was able to find a position at Harvard for him. They married in 1934 and often collaborated on studies of variable stars. She was named a lecturer in astronomy in 1938, but even though she taught courses, they were not listed in the Harvard catalog until after World War II.

In 1956 Payne was appointed a full professor at Harvard and became chairman of the astronomy department. She retired in 1966. She wrote an autobiography, ‘The Dyer’s Hand’, that was posthumously collected in ‘Cecilia Payne-Gaposchkin: An Autobiography and Other Recollections’ (1984).

5-10-Cecilia-Payne-Gaposchkin-205x300.jpg

#7 Re: Ganesh's Puzzles » Coordinate Geometry » Yesterday 15:09:11

Hi,

CG#61. Find the equation of a straight line having slope 3 and y-intercept -4.

#8 Re: Ganesh's Puzzles » Algebra » Yesterday 14:55:20

Hi,

.

A # 25. The ages of Kate and Kevin are 11 years and 14 years respectively. In how many years will the product of their ages will be 304?

#9 Re: Ganesh's Puzzles » Mensuration » Yesterday 14:38:34

Hi,

M # 553. A heap of paddy is in the form of a cone whose diameter is 4.2 meters and height 2.8 meters. If the heap is to be covered exactly by a canvas to protect it from rain, find the area of the canvas needed. Use

.

#10 Re: Ganesh's Puzzles » Mensuration » Yesterday 14:37:41

Hi,

M # 553. A heap of paddy is in the form of a cone whose diameter is 4.2 meters and height 2.8 meters. If the heap is to be covered exactly by a canvas to protect it from rain, find the area of the canvas needed. Use

.

#12 Re: This is Cool » Miscellany » Yesterday 00:57:15

359) Piezoelectricity

You've probably used piezoelectricity (pronounced "pee-ay-zo-electricity") quite a few times today. If you've got a quartz watch, piezoelectricity is what helps it keep regular time. If you've been writing a letter or an essay on your computer with the help of voice recognition software, the microphone you spoke into probably used piezoelectricity to turn the sound energy in your voice into electrical signals your computer could interpret. If you're a bit of an audiophile and like listening to music on vinyl, your gramophone would have been using piezoelectricity to "read" the sounds from your LP records. Piezoelectricity (literally, "pressing electricity") is much simpler than it sounds: it just means using crystals to convert mechanical energy into electricity or vice-versa. Let's take a closer look at how it works and why it's so useful!

What is piezoelectricity?

Squeeze certain crystals (such as quartz) and you can make electricity flow through them. The reverse is usually true as well: if you pass electricity through the same crystals, they "squeeze themselves" by vibrating back and forth. That's pretty much piezoelectricity in a nutshell but, for the sake of science, let's have a formal definition:

Piezoelectricity (also called the piezoelectric effect) is the appearance of an electrical potential (a voltage, in other words) across the sides of a crystal when you subject it to mechanical stress (by squeezing it).

In practice, the crystal becomes a kind of tiny battery with a positive charge on one face and a negative charge on the opposite face; current flows if we connect the two faces together to make a circuit. In the reverse piezoelectric effect, a crystal becomes mechanically stressed (deformed in shape) when a voltage is applied across its opposite faces.

What causes piezoelectricity?

Think of a crystal and you probably picture balls (atoms) mounted on bars (the bonds that hold them together), a bit like a climbing frame. Now, by crystals, scientists don't necessarily mean intriguing bits of rock you find in gift shops: a crystal is the scientific name for any solid whose atoms or molecules are arranged in a very orderly way based on endless repetitions of the same basic atomic building block (called the unit cell). So a lump of iron is just as much of a crystal as a piece of quartz. In a crystal, what we have is actually less like a climbing frame (which doesn't necessarily have an orderly, repeating structure) and more like three-dimensional, patterned wallpaper.

In most crystals (such as metals), the unit cell (the basic repeating unit) is symmetrical; in piezoelectric crystals, it isn't. Normally, piezoelectric crystals are electrically neutral: the atoms inside them may not be symmetrically arranged, but their electrical charges are perfectly balanced: a positive charge in one place cancels out a negative charge nearby. However, if you squeeze or stretch a piezoelectric crystal, you deform the structure, pushing some of the atoms closer together or further apart, upsetting the balance of positive and negative, and causing net electrical charges to appear. This effect carries through the whole structure so net positive and negative charges appear on opposite, outer faces of the crystal.

The reverse-piezoelectric effect occurs in the opposite way. Put a voltage across a piezoelectric crystal and you're subjecting the atoms inside it to "electrical pressure." They have to move to rebalance themselves—and that's what causes piezoelectric crystals to deform (slightly change shape) when you put a voltage across them.

What is piezoelectricity used for?

There are all kinds of situations where we need to convert mechanical energy (pressure or movement of some kind) into electrical signals or vice-versa. Often we can do that with a piezoelectric transducer. A transducer is simply a device that converts small amounts of energy from one kind into another (for example, converting light, sound, or mechanical pressure into electrical signals).

In ultrasound equipment, a piezoelectric transducer converts electrical energy into extremely rapid mechanical vibrations—so fast, in fact, that it makes sounds, but ones too high-pitched for our ears to hear. These ultrasound vibrations can be used for scanning, cleaning, and all kinds of other things.

In a microphone, we need to convert sound energy (waves of pressure traveling through the air) into electrical energy—and that's something piezoelectric crystals can help us with. Simply stick the vibrating part of the microphone to a crystal and, as pressure waves from your voice arrive, they'll make the crystal move back and forth, generating corresponding electrical signals. The "needle" in a gramophone (sometimes called a record player) works in the opposite way. As the diamond-tipped needle rides along the spiral groove in your LP, it bumps up and down. These vibrations push and pull on a lightweight piezoelectric crystal, producing electrical signals that your stereo then converts back into audible sounds.

In a quartz clock or watch, the reverse-piezoelectric effect is used to keep time very precisely. Electrical energy from a battery is fed into a crystal to make it oscillate thousands of times a second. The watch then uses an electronic circuit to turn that into slower, once-per-second beats that a tiny motor and some precision gears use to drive the second, minute, and hour hands around the clock-face.

Piezoelectricity is also used, much more crudely, in spark lighters for gas stoves and barbecues. Press a lighter switch and you'll hear a clicking sound and see sparks appear. What you're doing, when you press the switch, is squeezing a piezoelectric crystal, generating a voltage, and making a spark fly across a small gap.
If you've got an inkjet printer sitting on your desk, it's using precision "syringes" to squirt droplets of ink onto the paper. Some inkjets squirt their syringes using electronically controlled piezoelectric crystals, which squeeze their "plungers" in and out; Canon Bubble Jets fire their ink by heating it instead.

Energy harvesting with piezoelectricity?

If you can make a tiny bit of electricity by pressing one piezoelectric crystal once, could you make a significant amount by pressing many crystals over and over again? What if we buried crystals under city streets and pavements to capture energy as cars and people passed by? This idea, which is known as energy harvesting, has caught many people's interest. Inventors have proposed all kinds of ideas for storing energy with hidden piezoelectric devices, from shoes that convert your walking movements into heat to keep your feet warm, and cellphones that charge themselves from your body movements, to roads that power streetlights, contact lenses that capture energy when you blink, and even gadgets that make energy from the pressure of falling rain.

Is energy harvesting a good idea? At first sight, anything that minimizes waste energy and improves efficiency sounds really sensible. If you could use the floor of a grocery store to capture energy from the feet of hurrying shoppers pushing their heavy carts, and use that to power the store's lights or its chiller cabinets, surely that must be a good thing? Sometimes energy harvesting can indeed provide a decent, if rather modest, amount of power.

The trouble is, however, that energy harvesting schemes can be a big distraction from better ideas. Consider, for example, the concept of building streets with piezoelectric "rumble strips" that soak up energy from passing traffic. Cars are extremely inefficient machines and only a small amount (15 percent or so) of the energy in their fuel powers you down the road. Only a fraction of this fraction is available for recovery from the road—and you wouldn't be able to recover all that fraction with 100 percent efficiency. So the amount of energy you could practically recover, and the efficiency gain you would make for the money you spent, would be minuscule. If you really want to save energy from cars, the sensible way to do it is to address the inefficiencies of car transportation much earlier in the process; for example, by designing engines that are more efficient, encouraging people to car share, swapping from gasoline engines to electric cars, and things of that sort.

That's not to say that energy harvesting has no place; it could be really useful for charging mobile devices using energy that would otherwise go to waste. Imagine a cellphone that charged itself automatically every time it jiggled around in your pocket, for example. Even so, when it comes to saving energy, we should always consider the bigger picture and make sure the time and money we invest is producing the best possible results.

Who discovered piezoelectricity?

The piezoelectric effect was discovered in 1880 by two French physicists, brothers Pierre and Paul-Jacques Curie, in crystals of quartz, tourmaline, and Rochelle salt (potassium sodium tartrate). They took the name from the Greek work piezein, which means "to press."

piezoelectric_effect.jpg

#13 Re: Ganesh's Puzzles » Oral puzzles » Yesterday 00:41:16

Hi,

.

#4506. A coin is tossed thrice. Find the probability of of exactly two heads showing up.

#14 Re: Ganesh's Puzzles » Series and Progressions » Yesterday 00:25:46

Hi,

SP#555. Find the sum of first 40 positive integers divisible by 6.

#15 Re: Ganesh's Puzzles » General Quiz » Yesterday 00:14:21

Hi,

#7265. Name the  is the only tennis player (born 9 August 1938) to twice achieve a Grand Slam, in 1962 and 1969, and the latter remains the only time a man has done so in the Open Era. He also won eight Pro Slam titles, including the "pro Grand Slam" in 1967, and he contributed to five Davis Cup titles for Australia during an age when Davis Cup was deemed as significant as the four majors.

#7266. What is also referred to as the "Channel Slam" - still arguably the sport's biggest challenge?

#16 Re: Exercises » Compute the solution: » 2019-06-15 23:14:52

Hi,

647. The distance between the points (3, 1) and (0, x) is 5 units. Find x.

#17 Re: Ganesh's Puzzles » Mensuration » 2019-06-15 15:51:04

Hi,

M # 552. If the curved surface area of a solid hemisphere is 2772 square centimeters, find the total surface area. Use

.

#18 Re: Ganesh's Puzzles » Oral puzzles » 2019-06-15 15:24:22

Hi,

.

#4505.A machine is marked at $7500 for sale. The shopkeeper allows successive discounts of 8%, 5%, and 2% on it. Find the net Selling Price.

#20 Re: Ganesh's Puzzles » Coordinate Geometry » 2019-06-15 02:54:32

Hi,

The solution CG#59 is correct. Excellent, Monox D. I-Fly!

CG#60. If a straight line y = 2x + k passes through the point (1, 2), then find the value of k.

#21 Jokes » Bird Jokes - 1 » 2019-06-15 01:23:19

ganesh
Replies: 0

Q: What birds spend all their time on their knees?
A: Birds of prey!
* * *
Q: What did they call the canary that flew into the pastry dish?
A: Tweetie Pie!
* * *
Q: What do you call a very rude bird?
A: A mockingbird!
* * *
Q: Why couldn't anyone see the bird?
A: Because it was in da skies! (disguise).
* * *
Q: What kind of birds do you usually find locked up?
A: Jail-birds!
* * *
Q: What kind of math do birds like?
A: Owlgebra.
* * *
Q: How do you get a cut-price parrot?
A: Plant bird seed!
* * *
Q: How did the bird break into the house?
A: With a crow bar.
* * *

#22 Re: Ganesh's Puzzles » English language puzzles » 2019-06-15 01:12:26

Hi,

#3255. What does the adjective diffuse mean?

#3256. What does the verb (used with object) digitize mean?

#24 Re: Ganesh's Puzzles » Trigonometry » 2019-06-15 00:38:21

Hi,

.

T#125. If x is a positive acute angle , find the value of x if

.

#25 Re: Dark Discussions at Cafe Infinity » crème de la crème » 2019-06-15 00:21:00

532) James Arthur Gosling,

James Gosling (born May 19, 1955) is a Canadian computer scientist, best known as the founder and lead designer behind the Java programming language.

Education and career

James Gosling received a Bachelor of Science from the University of Calgary  and his M.A. and Ph.D. from Carnegie Mellon University, all in computer science. He wrote a version of Emacs called Gosling Emacs (Gosmacs) while working toward his doctorate. He built a multi-processor version of Unix for a 16-way computer system while at Carnegie Mellon University, before joining Sun Microsystems. He also developed several compilers and mail systems there.

Gosling was with Sun Microsystems between 1984 and 2010 (26 years). He is known as the father of the Java programming language. He got the idea for the Java VM while writing a program to port software from a PERQ by translating Perq Q-Code to VAX assembler and emulating the hardware. He left Sun Microsystems on April 2, 2010 after it was acquired by the Oracle Corporation, citing reductions in pay, status, and decision-making ability, along with change of role and ethical challenges. He has since taken a very critical stance towards Oracle in interviews, noting that "during the integration meetings between Sun and Oracle, where we were being grilled about the patent situation between Sun and Google, we could see the Oracle lawyer's eyes sparkle." He clarified his position during the Oracle v Google trial over Android: "While I have differences with Oracle, in this case, they are on the right. Google totally slimed Sun. We were all really disturbed, even Jonathan Schwartz; he just decided to put on a happy face and tried to turn lemons into lemonade, which annoyed a lot of folks on Sun." However, he approved of the court's ruling that APIs should not be copyrightable.

In March 2011, Gosling left Oracle to work at Google. Six months later, he followed his colleague Bill Vass and joined a startup called Liquid Robotics. In late 2016, Liquid Robotics was acquired by Boeing. Following the acquisition, Gosling left Liquid Robotics to work at Amazon Web Services as Distinguished Engineer in May 2017.

He is an advisor at the Scala company Lightbend, Independent Director at Jelastic, and Strategic Advisor for Eucalyptus, and is a board member of DIRTT Environmental Solutions.

He is known for his love of proving "the unknown" and has noted that his favorite irrational number is square root of 2. He has a framed picture of the first 1,000 digits of square root of 2 in his office.

Contributions

Gosling initially became known as the author of Gosling Emacs, and also invented the windowing system NeWS, which lost out to X Window because Sun did not give it an open source license. He is generally credited with having invented the Java programming language in 1994. He created the original design of Java and implemented the language's original compiler and virtual machine. Gosling traces the origins of the approach to his early graduate-student days, when he created a p-code virtual machine for the lab's DEC VAX computer, so that his professor could run programs written in UCSD Pascal. In the work leading to Java at Sun, he saw that architecture-neutral execution for widely distributed programs could be achieved by implementing a similar philosophy: always program for the same virtual machine.

For his achievement, the National Academy of Engineering in the United States elected him as a Foreign Associate member. Another contribution of Gosling's was co-writing the "bundle" program, a utility thoroughly detailed in Brian Kernighan and Rob Pike's book The Unix Programming Environment.

Honors

2002: he was awarded 'The Economist Innovation Award'.
2002: he was awarded 'The Flame Award USENIX Lifetime Achievement Award'.
2007: he was made an Officer of the 'Order of Canada'. The Order is Canada's second highest civilian honor. Officers are the second highest grade within the Order.
2013: he became a fellow of the 'Association for Computing Machinery'.
2015: awarded 'IEEE John von Neumann Medal'.
2019: named a 'Computer History Museum Fellow' for the conception, design, and implementation of the Java programming language.

james_gosling.jpg

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