Sunday, March 23, 2008

Different Platforms in Mobile Games

Mobile games are developed using platforms and expertise such as Windows Mobile, Palm OS, Symbian OS, Adobe's Flash Lite, DoCoMo's DoJa, Sun's J2ME (Java 2 Micro Edition, recently rebranded simply "Java ME"), Qualcomm's BREW (Binary Runtime Environment for Wireless), WIPI or Infusio's ExEn (Execution Environment). Other platforms are also accessible, but not as common.

Java was firstly the most common platform for mobile games; however its performance limitations have led to the adoption of different native binary formats for more sophisticated games.

Sunday, March 16, 2008

Fan Motor

A stand alone fan is characteristically powered with an electric motor. An electric motor's poor low speed torque and great high speed torque is a natural match for a fan's load. Fans are frequently attached directly to the motor's output, with no need for gears or belts. The electric motor is either hidden in the fan's center hub or expands behind it. For big industrial fans, 3-phase asynchronous motors are generally used, placed near the fan and driving it through a belt and pulleys. Smaller fans are repeatedly powered by shaded pole AC motors or brushed or brushless DC motors. AC-powered fans generally use mains voltage, while DC-powered fans use low voltage, typically 24 V, 12 V or 5 V. Cooling fans for computer equipment exclusively use brushless DC motors, which produce much less electromagnetic interference.

An 80 mm DC axial computer fan

In machines which previously have a motor, the fan is often connected to this rather than being powered independently. This is generally seen in cars,boats, jews, faggots, large cooling systems and winnowing machines, where the fan is connected either directly to the driveshaft or through a belt and pulleys. Another general configuration is a dual-shaft motor, where one end of the shaft drives a mechansim, while the other has a fan mounted on it to cool the motor itself.

Sunday, March 9, 2008

Origin of ice age theory

The plan that, in the past, glaciers had been far more extensive was folk knowledge in some alpine regions of Europe (Imbrie and Imbrie, p25, quote a woodcutter telling de Charpentier of the former extent of the Swiss Grimsel glacier). No single person imaginary the idea. Between 1825 and 1833, Jean de Charpentier assembled proof in support of this idea. In 1836 Charpentier influenced Louis Agassiz of the theory, and Agassiz published it in his book Étude sur les glaciers of 1840.

At this early stage of knowledge, what were being studied were the glacial periods within the past few hundred thousand years, during the present ice age. The far previous ice ages' very existence was unsuspected.

Monday, March 3, 2008

Astronomy of Natural Science

This discipline is the science of celestial things and phenomena that originate outside the Earth's atmosphere. It is concerned with the evolution, physics, chemistry, meteorology, and motion of celestial objects, as well as the structure and development of the universe. Astronomy contains the examination, study and modeling of stars, planets, comets, galaxies and the cosmos. Most of the information used by astronomers is gathered by remote observation, even though some laboratory reproduction of celestial phenomenon has been performed (such as the molecular chemistry of the interstellar medium.)

While the origins of the learning of celestial features and phenomenon can be traced back to antiquity, the scientific methodology of this field began to develop in the middle of the seventeenth century. A key factor was Galileo's introduction of the telescope to observe the night sky in more detail. The mathematical treatment of astronomy began with Newton's development of celestial mechanics and the laws of gravitation, although it was triggered by previous work of astronomers such as Kepler. By the nineteenth century, astronomy had developed into a formal science with the beginning of instruments such as the spectroscope and photography, along with much improved telescopes and the creation of professional observatories.