Solar Inverters

A solar inverter or PV inverter is a critical component in a Photovoltaic system. It performs the conversion of the variable DC output of the Photovoltaic (PV) modules into a utility frequency AC current that can be fed into the commercial electrical grid or used by a local, off-grid electrical network. An inverter allows use of ordinary mains-operated appliances on a direct current system. Solar inverters have special functions adapted for use with PV arrays, including maximum power point tracking and anti-islanding protection.

Classification :

    Stand-alone inverters, used in isolated systems where the inverter draws its DC energy from batteries charged by photovoltaic arrays. Many stand-alone inverters also incorporate integral battery chargers to replenish the battery from an AC source, when available. Normally these do not interface in any way with the utility grid, and as such, are not required to have anti-islanding protection.

    Grid tie inverters, which match phase with a utility-supplied sine wave. Grid-tie inverters are designed to shut down automatically upon loss of utility supply, for safety reasons. They do not provide backup power during utility outages.

    Battery backup inverters, are special inverters which are designed to draw energy from a battery, manage the battery charge via an onboard charger, and export excess energy to the utility grid. These inverters are capable of supplying AC energy to selected loads during a utility outage, and are required to have anti-islanding protection.

 Maximum power point tracking (MPPT) :

Maximum power point tracking is a technique that solar inverters use to get the maximum possible power from the PV array.Solar cells have a complex relationship between solar irradiation, temperature and total resistance that produces a non-linear output efficiency known as the I-V curve. It is the purpose of the MPPT system to sample the output of the cells and apply a resistance (load) to obtain maximum power for any given environmental conditions.[citation needed] Essentially, this defines the current that the inverter should draw from the PV in order to get the maximum possible power (since power equals voltage times current).

The fill factor, more commonly known by its abbreviation FF, is a parameter which, in conjunction with the open circuit voltage and short circuit current of the panel, determines the maximum power from a solar cell. Fill factor is defined as the ratio of the maximum power from the solar cell to the product of Voc and Isc.

There are three main types of MPPT algorithms: perturb-and-observe, incremental conductance and constant voltage.The first two methods are often referred to as hill climbing methods, because they depend on the fact that on the left side of the MPP, the curve is rising (dP/dV > 0) while on the right side of the MPP the curve is falling (dP/dV < 0).

Anti-islanding protection :

Normally, grid-tied inverters will shut off if they do not detect the presence of the utility grid.[citation needed] If, however, there are load circuits in the electrical system that happen to resonate at the frequency of the utility grid, the inverter may be fooled into thinking that the grid is still active even after it had been shut down. This is called islanding.

An inverter designed for grid-tie operation will have anti-islanding protection built in; it will inject small pulses that are slightly out of phase with the AC electrical system in order to cancel any stray resonances that may be present when the grid shuts down.

Since 1999, the standard for anti-islanding protection in the United States has been UL 1741, harmonized with IEEE 1547.Any inverter which is listed to the UL 1741 standard may be connected to a utility grid without the need for additional anti-islanding equipment, anywhere in the United States or other countries where UL standards are accepted.

Similar acceptance of the IEEE 1547 in Europe is also taking place, as most electrical utilities will be providing or requiring units with this capability.

Types of anti-islanding protection:

There are two types of anti-islanding control techniques:

Passive:

The voltage and/or the frequency change during the grid failure is measured and a positive feedback loop is employed to push the voltage and /or the frequency further away from its nominal value. Frequency or voltage may not change if the load matches very well with the inverter output or the load has a very high quality factor (reactive to real power ratio). So there exists some Non Detection Zone (NDZ). 

Active:
This method employs injecting some error in frequency or voltage. When grid fails, the error accumulates and pushes the voltage and/or frequency beyond the acceptable range.

 

Solar micro-inverters:

A solar micro-inverter in the process of being installed. The ground wire is attached to the lug and the panel's DC connections are attached to the cables on the lower right. The AC parallel trunk cable runs at the top (just visible).

Main article: Solar micro-inverter

Solar micro-inverters convert direct current (DC) from a single solar panel to alternating current (AC). The electric power from several micro-inverters is combined and sent to the consuming devices. The key feature of a micro-inverter is not its small size or power rating, but its one-to-one control over a single panel and its mounting on the panel or near it which allows it to isolate and tune the output of that panel.[citation needed] This also makes expanding the solar power system much easier since additional panels with microinverters can be added to the existing system without as much system change as in upgrading a conventional system with solar inverters.

Microinverters produce grid-matching power directly at the back of the panel. Arrays of panels are connected in parallel to each other and fed to the grid. This has the major advantage that a single failing panel or inverter will not take the entire string offline. Combined with the lower power and heat loads, and improved MTBF, it is suggested that overall array reliability of a microinverter-based system will be significantly greater than a string-inverter based one. Additionally, when faults occur, they are identifiable to a single point, as opposed to an entire string. This not only makes fault isolation easier, but unmasks minor problems that might never become visible otherwise - a single underperforming panel may not affect a short string's output enough to be noticed.

Microinverters have become common where array sizes are small and maximizing performance from every panel is a concern. In these cases the differential in price-per-watt is minimized due to the small number of panels, and has little effect on overall system cost. The improvement in energy collection given a fixed size array can offset this difference in cost. For this reason, microinverters have been most successful in the residential market, where the limited space for panels constraints the array size, and shading from nearby trees or other homes is often an issue. Micro-inverter manufacturers list many installations, some as small as a single panel and the majority under 50.

Another prime reason for the popularity of microinverters is the expandability. A solar array can start with as little as 1 panel & gradually have additional added to it with no maximum size. This is important as a standard string inverter will have to be replaced if the array grows outside of its capabilities.

Grid tied solar inverters:

Solar grid-tie inverters are designed to quickly disconnect from the grid if the utility grid goes down. This is an NEC requirement that ensures that in the event of a blackout, the grid tie inverter will shut down to prevent the energy it produces from harming any line workers who are sent to fix the power grid.

Grid-tie inverters that are available on the market today use a number of different technologies. The inverters may use the newer high-frequency transformers, conventional low-frequency transformers, or no transformer. Instead of converting direct current directly to 120 or 240 volts AC, high-frequency transformers employ a computerized multi-step process that involves converting the power to high-frequency AC and then back to DC and then to the final AC output voltage.

The issue at stake currently is that there are concerns about having transformerless electrical systems feed into the public utility grid since the lack of galvanic isolation between the DC and AC circuits could allow the passage of dangerous DC faults to be transmitted to the AC side.

Many solar inverters are designed to be connected to a utility grid, and will not operate when they do not detect the presence of the grid. They contain special circuitry to precisely match the voltage and frequency of the grid.

Solar charge controller:

A charge controller may be used to power DC equipment with solar panels. The charge controller provides a regulated DC output and stores excess energy in a battery as well as monitoring the battery voltage to prevent under/over charging. More expensive units will also perform maximum power point tracking. An inverter can be connected to the output of a charge controller to drive AC loads.

Solar pumping inverters :

Advanced solar pumping inverters convert DC voltage from the solar array into AC voltage to drive submersible pumps directly without the need for batteries or other energy storage devices. By utilizing MPPT (maximum power point tracking), solar pumping inverters regulate output frequency to control speed of the pumps in order to save pump motor from damage.

 

Inverter failure:

Solar inverters may fail due to transients from the grid or the PV panel, component aging and operation beyond the designed limits.

12 Amazing Creations Made From Computer Chips and Circuit Boards !

Artists have their own passion for creating oddities that they know will definitely impress. We have seen people coming up with amazing creations from electronic waste and here we have 12 amazing creations made from discarded computer chips and circuit boards. Hit the jump to see the beauty of the rejected chips and circuit board creations.

1. Circuit Egg:

This 7-foot-tall sculpture created by Brazilian artists Adriana Varella and Nilton Maltz bleds technology and art together. Installed in 2005 at Lytton Plaza in Palo Alto, the Circuit Egg is made using recycled circuit board.

2. Gabriel Dishaw’s funky Nike shoe:

Recycle, reduce and reuse is what we have been listening to for quite some time now. Gratifying the logo is Gabriel Dishaw with Nike-inspired Frankenstein Terminators junk art, a shoe made from circuit boards.

3. Mono Lisa from motherboards and chips:

Proving that junk art isn’t a legacy of the sculptors alone, Asus has put some dead motherboards and chips together to create what is considered an unsolved mystery in art – the Mono Lisa.

4. Solar panels from computer chips:

IBM has come up with an ingenious idea of creating solar panels from waste computer chips. Each chip has tiny bit of silicon on it that can be used to make solar panels. IBM estimates that 3 million silicon wafers are sent to landfills annually, which if transformed to solar panels can power 6,000 homes.

5. Circuit-board jewelry:

Christoph Koch has designed contemporary jewelry using circuit boards. The designer created two chic circuit-board necklaces, making a great fashion statement.

6. Photo-frame from recycled circuit board:

It’s unimaginable how the parts that were made to head for the landfill has taken an elegant place in your bed room or drawing room desktop! This attractive photo frame is made from recycled circuit board.

7. Fabio Renaldo’s computer chip dress:

For the Eco Chic fashion shows in Jakarta a designer collected discarded computer chips and shaped it into a beautiful dress. Fabio Renaldo has balanced the heaviness of the shimmery metal and light flow of the silky material perfectly.

8. Circuit board bench:

Did you ever imagine that circuit board could be good to sit too? Well, this circuit board bench exemplifies that. Not only does it look durable and comfortable, but also aesthetically pleasing.

 
9. Eco-Green Clock:

Done at the TEcoArt, this Eco-Green Clock wears a mirror-finished disk platter with hour and minute hands and a zigzag second hand over a circuit board base.

10. Wild life out of circuit board:

Brenda Guyton has breathed new life into computer circuit boards and chips. The artist has beautifully transformed computers parts that are considered nothing more than waste into unique sculptures like Jack the jack rabbit, K-9 a good dog and guanagator.

11. High-tech dinosaur:

Bringing the memories of the dinosaurs back to life is the High-tech dinosaur. This sculpture brings the discarded circuit boards into life. Not only does it divert trash from ending up in landfills, but also exemplifies beauty.

12. Clocks and lighting from computer circuit:

Clocks, accessories, decorative items and chic lightings, all under one roof. And what are they made of? Circuit boards and chips…Isn’t that wonderful. Each piece is exceptionally beautiful and green.

Magnet Car !

Declared as one of the most eco friendly cars, this car overcomes the force of gravity through the strategic use of an electric engine. Matúš Procháczka finds an unusual solution to the problem of, expending fuel to get somewhere rather than finding a different fuel source, or building a smaller car. He ingeniously reduces the weight of the car by using an electric engine with magnets the same polarity as the roads, the resulting upward force lightens the vehicle’s weight by 50%. Another innovative touch is the desing of the seats: two outer layers, pile yarn, and a soft construction foam make it possible to adjust the final hardness and spring characteristics of the seat,this lightweight, adaptable seating not only cuts down on waste during construction and the overall weight of the vehicle while being driven, it also sounds pretty darn comfy.

Restaurant in the Sky

When it comes to Las Vegas dining the skys the limit, literally. Dinner in the Sky offers an extreme dining experience by suspending its hungry patrons more than 160 feet above ground. Diners are seated around a large table and safely secured in their seats before a crane lifts the dining platform up into the air for a stunning panoramic view of The Las Vegas Strip and surrounding desert. Before liftoff, guests can mingle in the Sky Lounge, sip Champagne and nibble on some hors doeuvres. Diners have the option to book a table for a group or join one of the regularly scheduled flights, which are listed on the Web site.

The Menu: A choice of two entrées includes the Take It to the Top, filet medallions with bordelaise sauce sautéed in mushrooms, or the Sky Chicken, a baked chicken breast stuffed with prosciutto, artichokes and gorgonzola cheese. Vegetarian options are available upon request. Desserts and hors doeuvres are chefs choice and promise a tasty beginning and end to your meal.

 

The Must-Have: The red carpet VIP reception includes a drink and a photo that shows you looking like a celebrity about to hop on your private magic carpet ride for dinner. For extra pampering and a mere $20, you can arrange for hotel pick-up and drop-off.

Inventors Killed By Their Own Inventions

It’s all fun and games… until something you invent ends up killing you. Inventing new products or processes is not easy. It’s challenging and risky and sometimes, just sometimes, lady luck decides to look the other way and in a cruel twist of fate with a tinge of irony, you end up losing your life to the hands of your own creation. Here’s a list of ten brave inventors who, in the process of trying to make the lives of others better, lost their own.

1. Thomas Midgley- Leaded Petrol and Mechanical Bed

Thomas Midgley, an American chemist who developed both leaded petrol and chlorofluorocarbons (CFCs), was notoriously known as ‘the one human responsible for more deaths than any other in history’. As if it was nature’s idea to get revenge on him he was left disabled in his bed due to lead poisoning and polio at the age of 51. Keeping his inventive juices flowing, he designed a complicated system of strings and pulleys on his bed so that he could lift himself up when needed. This invention was the cause of his death at the age of 55 when he was accidentally entangled in the ropes of his bed and died of strangulation. Talk about double irony.

2. Otto Lilienthal - Hang Glider

‘To invent an airplane is nothing. To build one is something. But to fly is everything’ - famous words uttered by Otto Lilienthal who was one of the pioneers of human aviation and invented the first few hang gliders. He made over 2500 successful flights using his own inventions for five straight years starting from 1891 until one fateful day, in the mid of 1896, his glider lost lift and he crashed from a height of 17m (56 feet). The impact broke his spine and a day later, he succumbed to his injuries. His last words are a source of inspiration for all those who face numerous obstacles in life while trying to achieve something big: ‘Small sacrifices must be made!’

3. Franz Reichelt- The Overcoat Parachute

Franz Reichelt an Austrian born tailor of the 1800’s was most famously known for inventing an overcoat which he claimed to act as a parachute and could bring its wearer gently to the ground or even to fly under the right conditions. This inventor, who was also called the ‘The Flying Taylor’, attempted to demonstrate his invention by jumping off the first deck of the Eiffel tower himself instead of using a dummy, in front of a large crowd of spectators and camera crew. The result? The parachute failed to deploy and he crashed into the hard concrete ground at the foot of the tower, the impact immediately killing him.

4. Alexander Bogdanov- Blood Transfusion

A renowned Russian physician, philosopher, economist, science fiction writer, and revolutionary, Alexander Bogdanov developed a sudden interest in the possibility of human rejuvenation through blood transfusions. In hopes of achieving eternal youth and bodily revitalization, he undertook 11 blood transfusions, ultimately reporting an improvement in eyesight and reduction of balding. Great invention, right? Wrong. Bogdanov died in 1928, after he did a transfusion on himself with blood from a student that had tuberculosis and malaria.

5. William Bullock- Rotary Printing press

In the history of bizarre accidents, William Bullock’s story is always cited as an example. Bullo ck was an American inventor whose 1863 invention of the rotary printing press helped revolutionize the printing industry due to its efficiency and ability to print 10,000 units per hour. In April 1867, while he was trying to install a new printer in one of his presses, in a frustrated attempt to make adjustments to the machine, he kicked a driving belt onto a pulley. What followed next tops scenes from even the most gruesome movies like Hostel and Saw. His foot got caught in the merciless contraption, was crushed beyond repair and developed a severe gangrene infection for four days. Bullock died during an operation to amputate his foot. Bizarre Indeed.

6. Cowper Coles Turret Ship 

A famous Chinese stateman once said: “Weapons are an important factor in war, but not the decisive one; it is man and not materials that counts” I guess Cowper Coles should have really taken that thought into consideration before inventing the turret ship- an ironclad war vessel, with low sides, on which heavy guns are mounted on a low structure, which may be rotated. The ship was so overly loaded with armored structures that they shifted its centre of gravity and caused it to become unstable resulting in the vessel capsizing on 6th September 1870. Cowper Coles was one of the 500 that died when it sunk. Only 18 of its crew survived.

7. Henry Winstanley  Lighthouse

Necessity is the mother of invention. Sure enough, after losing not one but two of his ships on the treacherous Eddystone Reef, Winstanley, a famous English architect and engineer felt it necessary to construct a lighthouse for the protection of his own and other ships. In the early 1700’s he invented the first Eddystone Lighthouse and proudly told the world that he wished he could "be in the light-house during the greatest storm that ever was". Little did he know his prayer would soon be answered on the night of November 26th, 1703, when one of the most destructive hurricanes Great Britain has ever experienced shook the reefs and did incalculable damage. In the morning, when the skies finally cleared, and ships reached Eddystone Rocks, Winstanley's great lighthouse was gone. And he was gone with it.

8. John Godfrey Parry-Thomas 

Welsh motor-racing driver and engineer J.G Parry Thomas, with a strong desire to regain his title as land speed record holder, a title snatched away from him by Malcom Campbell, decided to create a special type of vehicle to achieve his dream. His invention was a car he called Babs, which had many modifications, such as exposed chains to connect the engine to the drive wheels and the high engine cover requiring him to drive with his head tilted to only the right side. On trying to reclaim his record from Campbell, in the final race, the right-hand drive chain broke at a speed of 170 mph (270 km/h), flew into his neck, partially decapitating him and causing a head injury. He died instantly.

9. Marie Curie- Radioactive substances

Ever wondered where the word ‘Polonium’ came from? Well, it came from a Polish physicist and chemist and Nobel Prize winner Marie Curie who named her newly discovered chemical after her native country. Ever wondered what happened to this discoverer of Polonium, Radium and Theory of Radioactivity? She died on July 4, 1934, from aplastic anemia, as a result of exposure to radiation after working continuously in a small enclosed shed without any safety measures because radiation’s danger were not well understood at that time.

10. Donald Campbell Speed engine for motorboat

Speed thrills but kills. We all know it yet we all ignore it. It’s human nature to challenge well known facts of life. British car and motorboat racer Donald Campbell was no different. He broke eight world speed records in the 1950s and 60s and to quench his insatiable drive to conquer speed he decided to try for another water speed record in 1966. This time the target was 300 mph. He invented a lighter and more powerful engine for his boat Bluebird K7. Blame it on adrenaline rush or sheer stupidity but instead of refueling and waiting for the wash of his first run to subside, as is usual with speedboat races, Campbell decided to make a return run immediately. The craft's stability began to falter as it travelled over the rough water and it somersaulted at a 45 degree angle plunging back into the lake and disintegrating at a speed of 320mph. Needless to say, the inventor was killed.

Saudi Arabia’s Kingdom Tower !

Chicago-based firm Adrian Smith + Gordon Gill (AS+GG) has officially been announced as the design architects for the Kingdom Tower that is to be built in Jeddah, Saudi Arabia. Initially planned to stand one mile (1.6 km) high and be called the Mile-High Tower, the building was scaled down after soil testing in the area in 2008 cast doubt over whether the location could support a building of that height. Now the building will stand over 0.62 miles (one kilometer) tall, which will still allow it to overshadow the 2,717 ft. (828 m) Burj Khalifa to claim the title of the world's tallest building.

 

The Kingdom Tower will be the centerpiece and first construction phase of Kingdom City, a 57 million square foot (5.3 million m2) development located along the Red Sea north of Jeddah, which is known as the traditional gateway to the holy city of Mecca. The entire development has been budgeted at US$20 billion, with the Kingdom Tower alone costing approximately $1.2 billion to construct and covering an area of 5.7 million square feet (530,000 m2).

 

The building will contain 59 elevators, including 54 single-deck and five double-deck elevators, as well as 12 escalators. The elevators serving the observatory will travel at 22 mph (36 km/h) in both directions. At level 157, a sky terrace roughly 98 feet (30 m) in diameter intended as an outdoor amenity for use by the penthouse floor extends from the side of the building.

 

The exterior wall system is designed to minimize energy consumption by reducing thermal loads, while a series of notches on the building's three sides create pockets of shadow that shield areas of the building from direct sunlight and provide outdoor terraces.

 

The three-sided tower rises from a three-petal footprint design with aerodynamic tapering wings that help reduce structural loading due to wind vortex shedding. Gill says the tower's sleek, streamlined form was inspired by the folded fronds of young desert plant growth.

"With its slender, subtly asymmetrical massing, the tower evokes a bundle of leaves shooting up from the ground - a burst of new life that heralds more growth all around it," added Smith.

While the building's exact height isn't yet known, when completed AS+GG claim it will be at least 568 feet (173 m) taller than the Burj Khalifa, which was also designed by Adrian Smith when he was at architectural firm Skidmore, Owings & Merrill (SOM). At SOM, Smith also worked on the design for the Pearl River Tower, while AS+GG also recently won an international competition to design China's Wuhan Greenland Center.

 

AS+GG says design development of the Kingdom Tower is underway, the foundation drawings are already complete and construction is set to begin 'imminently."

What is Offshore Engineering ?

Since 1926 Dredging Engineering and since 1975 Offshore Engineering courses are given at the Delft University of Technology. In 2004 these two specialisations merged and formed the new MSc programme Offshore Engineering, a two-year curriculum leading to the MSc degree in Offshore Engineering. The programme consists of four specialisations: Fixed (Bottom Founded) Structures, Floating Structures, Subsea Engineering and Dredging Engineering.

Offshore Engineering is multidisciplinary and is a cooperation between Civil Engineering, Mechanical Engineering and Marine Technology.

Offshore & Dredging Engineers make structures such as fixed and floating platforms for the oil and gas industry. They also design undersea pipelines and other underwater equipment for this sector. An important feature is the design of dredging equipment for land reclamation, maintenance and the recovery of embedded minerals in deep-sea locations. Another application of offshore engineering is the design of offshore wind farms. Offshore & Dredging Engineers are the people who design facilities for the 70% of the earth's surface area that is not land.

Scope
The offshore & dredging industry is a relatively young, international industry, which has expanded globally in the last fifty years. Almost all new offshore & dredging engineers work in the private sector. The offshore & dredging industry's relative 'youth' means that problems often arise that have never been encountered before. This means that offshore & dredging workers (and students of offshore & dredging engineering) must possess a great deal of ingenuity and demonstrate initiative in addressing and resolving problems.

Top 10 Amazing Accidental Inventions !

Louis Pasteur once said, "chance favors the prepared mind." That's the genius behind all these accidental inventions - the scientists were prepared. They did their science on the brink and were able to see the magic in a mistake, set-back, or coincidence.

No. 10 - Saccharin

Saccharin, the sweetener in the pink packet, was discovered because chemist Constantin Fahlberg didn't wash his hands after a day at the office. Prepare to get icked. The year was 1879 and Fahlberg was trying to come up with new and interesting uses for coal tar. After a productive day at the office, he went home and something strange happened. He noticed the rolls he was eating tasted particularly sweet. He asked his wife if she had done anything interesting to the rolls, but she hadn't. They tasted normal to her. Fahlberg realized the taste must have been coming from his hands -- which he hadn't washed. The next day he went back to the lab and started tasting his work until he found the sweet spot.

No. 9 - Smart Dust

Most people would be pretty upset if their homework blew up in their faces and crumbled into a bunch of tiny pieces. Not so student Jamie Link. When Link was doing her doctoral work in chemistry at the University of California, San Diego, one of the silicon chips she was working on burst. She discovered afterward, however, that the tiny pieces still functioned as sensors. The resulting "smart dust" won her the top prize at the Collegiate Inventors Competition in 2003. These teensy sensors can also be used to monitor the purity of drinking or seawater, to detect hazardous chemical or biological agents in the air, or even to locate and destroy tumor cells in the body.

No. 8 - Coke

There are many stories of accidentally invented food: the potato chip was born when cook George Crum (yes, really his name!) tried to silence a persnickety customer who kept sending french fries back to the kitchen for being soggy; Popsicles were invented when Frank Epperson left a drink outside in the cold overnight; and ice cream cones were invented at the 1904 World's Fair in St. Louis. But no food-vention has had as much success as Coke. Atlanta pharmacist John Pemberton was trying to make a cure for headaches. He mixed together a bunch of ingredients -- and don't ask, because we don't know; The recipe is still a closely guarded secret. It only took eight years of being sold in a drug store before the drink was popular enough to be sold in bottles.

No. 7- Teflon

After all the damage they've done to the ozone layer, chlorofluorocarbons, or CFCs, are persona non grata. Back in the 1930s, however, they were (pardon the pun) the hot new thing in the science of refrigeration. Young DuPont chemist Roy Plunkett was working to make a new a new kind of CFC. He had a theory that if he could get a compound called TFE to react with hydrochloric acid, he could produce the refrigerant he wanted. So, to start his experiment Plunkett got a whole bunch of TFE gas, cooled it and pressured it in canisters so it could be stored until he was ready to use it. When the time came to open the container and put the TFE and hydrochloric acid together so they could react, nothing came out of the canister. The gas had disappeared. Only it hadn't. Frustrated and angry, Plunkett took off the top of the canister and shook it. Out came some fine white flakes. Luckily for everyone who's ever made an omelet, he was intrigued by the flakes and handed them off to other scientists at DuPont.

No. 6 - Vulcanized Rubber

Charles Goodyear had been waiting years for a happy accident when it finally occurred. Goodyear spent a decade finding ways to make rubber easier to work with while being resistant to heat and cold. Nothing was having the effect he wanted. One day he spilled a mixture of rubber, sulfur and lead onto a hot stove. The heat charred the mixture, but didn't ruin it. When Goodyear picked up the accident, he noticed that the mixture had hardened but was still quite usable. At last! The breakthrough he had been waiting for! His vulcanized rubber is used in everything from tires, to shoes, to hockey pucks.

No. 5 - Plastic

In 1907 shellac was used as insulation in electronics. It was costing the industry a pretty penny to import shellac, which was made from Southeast Asian beetles, and at home chemist Leo Hendrik Baekeland thought he might turn a profit if he could produce a shellac alternative. Instead his experiments yielded a moldable material that could take high temperatures without distorting. Baekeland thought his "Bakelite" might be used for phonograph records, but it was soon clear that the product had thousands of uses. Today plastic, which was derived from Bakelite, is used for everything from telephones to iconic movie punch lines.

No. 4 - Radioactivity

Two words that you don't ever want to hear said in the same sentence are "Whoops!" and "radioactive." But in the case of physicist Henri Becquerel's surprise discovery, it was an accident that brought radioactivity to light. Back in 1896 Becquerel was fascinated by two things: natural fluorescence and the newfangled X-ray. He ran a series of experiments to see if naturally fluorescent minerals produced X-rays after they had been left out in the sun. One problem - he was doing these experiments in the winter, and there was one week with a long stretch of overcast skies. He left his equipment wrapped up together in a drawer and waited for a sunny day. When he got back to work, Becquerel realized that the uranium rock he had left in the drawer had imprinted itself on a photographic plate without being exposed to sunlight first. There was something very special about that rock. Working with Marie and Pierre Curie, he discovered that that something was radioactivity.

No. 3 - Mauve

Talk about strange connections - 18-year-old chemist William Perkin wanted to cure malaria; instead his scientific endeavors changed the face of fashion forever and, oh yeah, helped fight cancer. Confused? Don't be. Here's how it happened. In 1856 Perkin was trying to come up with an artificial quinine. Instead of a malaria treatment, his experiments produced a thick murky mess. But the more he looked at it, the more Perkin saw a beautiful color in his mess. Turns out he had made the first-ever synthetic dye. His dye was far better than any dyes that came from nature; the color was brighter, more vibrant, and didn't fade or wash out. His discovery also turned chemistry into a money-generating science - making it attractive for a whole generation of curious-minded people. But the story is not over yet. One of the people inspired by Perkin's work was German bacteriologist Paul Ehrlich, who used Perkin's dyes to pioneer immunology and chemotherapy.

No. 2 - Pacemaker

 

This list wouldn't be complete without at least one absent-minded professor. But it's not flubber clocking in at No. 2, it's a life saving medical device. That pacemaker sewn into a loved one's chest actually came about because American engineer Wilson Greatbatch reached into a box and pulled out the wrong thing. It's true. Greatbatch was working on making a circuit to help record fast heart sounds. He reached into a box for a resistor in order to finish the circuit and pulled out a 1-megaohm resistor instead of a 10,000-ohm one. The circuit pulsed for 1.8 milliseconds and then stopped for one second. Then it repeated. The sound was as old as man: a perfect heartbeat.

No. 1 - Penicillin

 

You read this far into the list looking for penicillin, didn't you? That's OK. As one of the most famous and fortunate accidents of the 20th century, penicillin belongs at No. 1 on this list. If you've been living under a rock for the past 80 years or so, here's how the popular story goes: Alexander Fleming didn't clean up his workstation before going on vacation one day in 1928. When he came back, Fleming noticed that there was a strange fungus on some of his cultures. Even stranger was that bacteria didn't seem to thrive near those cultures. Penicillin became the first and is still one of the most widely used antibiotics.

Eye Ball !

A globe studded with cameras captures a panorama if you throw it in the air.

If you toss this foam-covered ball skyward, an accelerometer inside determines when it has reached its maximum height. At that moment, 36 cameras are triggered simultaneously, creating a mosaic that can be downloaded and viewed on a computer as one spherical panoramic image. The ball was created by researchers at the Technische Universität Berlin after one of them, Jonas Pfeil, labored to create panoramas while on vacation in Tonga. On that trip, he tried a cumbersome process that required snapping pictures in different directions and stitching them together later in a photo-editing program. Now he hopes to license the camera-ball technology for commercial production.

A. Outer Shell

The sphere, about the size of a softball, is protected by blocks of foam. Thirty-six cell-phone camera modules, each with a resolution of two megapixels, are set into the surface. Each module stores its portion of the mosaic until it is transferred to the ball's microcontroller.

B. Inner Shell

The prototype's inner shell, made from a strong yet somewhat flexible nylon material, gives the ball structural strength. The shell was made using a 3-D printing service.

C. Power Source

The ball's power source, a relatively heavy lithium-polymer battery, is secured in an inner cage to keep its center of gravity close to its geometric center so that it behaves predictably when thrown.

D. Microcontroller

A microcontroller uses data from an accelerometer to determine when to trigger the cameras. Then it stores the resulting mosaic of images. The prototype can store one mosaic, but it has a hardware slot for a memory card that could store additional panoramas.

E. Panorama

Images are uploaded to a personal computer via a USB connection. Software on the computer allows panoramas to be rotated or enlarged, and portions can be exported as 2-D images.