Building A Tilting Trike

Who speaks for Earth?

When I was eleven I bought my first book about science. It was called "Cosmos" and my parents had never seen a book so rare. Right now I'm seeing it on the shelf.

ten years ago today, Carl Sagan died, a wonderful science writer and a researcher of merit. A good biography would force me to talk about his contribution to the study represented by the Mars Viking missions , risk analysis and Nuclear Winter struggle to reduce the likelihood of nuclear war or their studies on the effect runaway greenhouse as we see Venus. Omalaled sure could do it beautifully.

But I prefer to speak of the fascination of a kid who discovers a huge world to explore in a single grain of sand. Of sense of surprise and wonder to understand that we are a unique product of evolution, an irreplaceable treasure. Of our smallness in the midst of leaving tiny Cosmos both our personal problems, as the ambitions and aspirations of dictators and autocrats throughout history. I read and reread a book avidly as I moved from ancient Greece to the far reaches of the solar system. Since the beginning of the universe to the possibility of complete destruction by our own hand, in a deliberate war or induced by a silly mistake. Even today, twenty years later, it remains a book to learn and think. Later

read many more books, both Sagan and other authors, who helped me to extend and complete that initial image. But Carl Sagan and "Cosmos" acted as the master copy that you just define your career. After reading "Cosmos" had to be science. And he must try to maintain a vision as broad and as varied as generous as possible. It's the same curiosity with which I'm reading books and blogs. And in a way and at a much more modest scale, is the attempt to return. Today we have millions of pages and blogs talking on behalf of the Earth. I think Carl Sagan would have been happy.


Category: Science in general , History of Science

Matlab Release 14 Sale

liquid lenses for small and large square windows

Last week I told my problems by placing a mirror. As a fragile material would not hurt to develop a good enough plastic to replace glass. But the most curious development being the use of liquids such as mirrors, telescopes both large and small lenses in a phone.

A backwater lake or a river were long the only mirrors. A layer of quiet and smooth liquid served to reflect the images. It is therefore not surprising that since Isaac Newton , was thought to use liquids to replace lenses, much more expensive, delicate and difficult to polish. The ideal candidate was mercury, a liquid metal, easy to use and with good optical properties. Although, in contrast, is quite toxic .

The next step was to focus images properly. The solution was to put the mercury in a flat container and turn it. The combined forces of gravity and the rotation curve slightly the mercury surface giving a parabolic shape. But to reduce the amount of mercury and used plastic discs are used in a dish with a thin layer of mercury at the top.



"Advantages? Cost only about 1% of a conventional mirror. And they are much lighter and cheaper. Even adding the cost of the other responsible for turning the mirror. In fact, there are already plans to build large telescopes on the Moon using this technology. On Earth using telescopes six meters for special applications .





One drawback, it must be said can only be directed from above, ie vertically upwards. This greatly limits the objects that can be observed and the time to do because the spin of the Earth away from the telescope of any chosen target.


I wonder if anyone will have thought of using electrically charged liquid and electric fields to change that orientation. Because something like this behind a new design of liquid lenses for cameras and mobile phones. The company Varioptic designed a lens containing two liquids of a contact surface changes shape by applying an electric field. After a couple of years of development seems to have finally achieved a sufficiently advanced product for use in real models . Philips has also developed a similar technology .



is interesting that even common elements such as mirrors can be changed with a little technology. A technology that reminds us of the world's oldest mirror.

Category: Physical

Largest Flatbed Scanners

jets

This week we put a square mirror in the bathroom. In the process ended with a small crack in one corner, a sign we are not too "hands" and that reminded me as a square windows helped change the history of aviation.

The British De Havilland Comet was the first reactor passengers. Created in 1952 served as a standard of superior British aviation technology at that time, the Russians and Americans. Its beautiful design, with engines embedded in the wings, called the attention of passengers. Unfortunately, the designers decided, also for purely aesthetic reasons, the windows should be square.






Initially all went well. For two years he was the master of the skies as Boeing tried to complete the development of their first civil reactor, the 707 . And then disaster struck. After several accidents, and especially after two unexplained crashes in January and April 1954 it was decided to ground the rest of the planes to find out what was happening.

Al pressurized to simulate in a pool cycles of ascent and descent of the aircraft was discovered that, along with the corners of windows, cracks appeared in the fine aircraft fuselage. These cracks grew gradually until rupture and cause catastrophic depressurization of the fuselage. What was happening?

The phenomenon is known as " material fatigue." Known since antiquity but difficult to analyze and was not sufficiently taken into account. Basically consists of a material breach after applying a little effort, far less than the maximum rupture stress. In fact, this latest strain is the classic drop breaks the camel. To produce the rupture, the material has previously suffered a lot of effort in cycles. These forces accumulate cracks and dislocations in the structure of the material that eventually cause breakage. The result is difficult to estimate accurately but there are approximate formulas to calculate the length of the fuselage of an airplane, a bridge or other structure. And always good to proper maintenance to detect cracks before they grow too much.

Proper design also helps. The substitution of other oval square windows along with other structural improvements eliminated the problem of the Comet. Unfortunately he could not recover from the terrible loss of confidence that caused the accident. The Americans began to control the market until the arrival of Airbus .

is not the only case. When the calculations fail or maintenance accidents occur as the train derailment high speed the offshore dump or molasses massive floods that follow smelling for years. Better not overwhelmed by a simple mirror.

Category: Physical