11 résultats pour "cylinder"

• Cylinder.

• Steam Engine.

  wear caused by this pressure, steam-engine valves are frequently made in a cylindrical form entirely enclosing the piston, so that the pressure is equal all around thevalve and friction is minimized. The development of this type of valve is attributed to the American inventor and manufacturer George Henry Corliss. In other types ofslide valves, the moving portion of the valve is designed so that steam does not press directly on the back of the valve. The linkage between the piston of the engine...

• Internal-Combustion Engine.

  any Otto-cycle engine and in actual engines today is slightly more than 40 percent. Diesels are, in general, slow-speed engines with crankshaft speeds of 100 to 750revolutions per minute (rpm) as compared to 2500 to 5000 rpm for typical Otto-cycle engines. Some types of diesel, however, have speeds up to 2000 rpm. Becausediesels use compression ratios of 14 or more to 1, they are generally more heavily built than Otto-cycle engines, but this disadvantage is counterbalanced by theirgreater effici...

• Map - Geography.

  Often only southeast slopes are hachured or shaded, giving somewhat the effect of a bird's-eye view of the area illuminated by light from the northwest. Shadings orcarefully drawn hachures, neither of which give elevations, are more easily interpreted than contour lines and are sometimes used in conjunction with them for greaterclarity. IV MAP PROJECTIONS For the representation of the entire surface of the earth without any kind of distortion, a map must have a spherical surface; a map of this...

• Mesopotamian Art and Architecture I INTRODUCTION Mesopotamian Art and Architecture, the arts and buildings of the ancient Middle Eastern civilizations that developed in the area (now Iraq) between the Tigris and Euphrates rivers from prehistory to the 6th century BC.

  arts. III EARLY DYNASTIC PERIOD Figures from Tell AsmarCreated around 2700 bc, these stone figures are from the city of Tell Asmar in what today is Iraq. From the Temple ofAbu, the statuettes stood in watchful prayer with the wide, staring eyes often found in Sumerian sculpture. The figuresare in the Iraq Museum, Baghdād, Iraq.Art Resource, NY The first historical epoch of Sumerian dominance lasted from about 3000 BC until about 2340 BC. While earlier architectural traditions continued, a ne...

• Thomas Edison.

  While Edison was working on the electric light, he made a scientific discovery that would become important to future generations. Edison noticed that particles of carbonfrom the filament blackened the insides of his light bulbs. This effect was caused by the emission of electrons from the filament, although Edison made the discoverybefore he and other scientists knew the electron existed. Not until 1897 did British physicist J. J. Thomson prove that the blackening observed by Edison was caused b...

• Thomas Edison - USA History.

  While Edison was working on the electric light, he made a scientific discovery that would become important to future generations. Edison noticed that particles of carbonfrom the filament blackened the insides of his light bulbs. This effect was caused by the emission of electrons from the filament, although Edison made the discoverybefore he and other scientists knew the electron existed. Not until 1897 did British physicist J. J. Thomson prove that the blackening observed by Edison was caused b...

• Poliomyelitis.

  Physical therapy helps patients with paralytic polio stretch and move affected muscles. This movement minimizes the atrophy, or shrinkage, of affected muscles andlimbs and builds strength. Exercises can also retrain working muscles to compensate for other muscles that have permanently lost the ability to move. Rehabilitativetherapy trains patients to use braces, crutches, and other devices that provide support and aid mobility. V PREVENTION OF POLIO Immunization with polio vaccine is the best w...

• aircraft, Japanese

• Automobile.

  Electric motors have been used to power automobiles since the late 1800s. Electric power supplied by batteries runs the motor, which rotates a driveshaft, the shaftthat transmits engine power to the axles. Commercial electric car models for specialized purposes were available in the 1980s. General Motors Corporation introduced amass-production all-electric car in the mid-1990s. Automobiles that combine two or more types of engines are called hybrids. A typical hybrid is an electric motor with ba...

• Submarine.

  B Propulsion Modern submarines use either diesel-electric or nuclear power to drive the sub's propeller and to provide internal electric power. Diesel-electric power emerged as themost efficient propulsion system for submarines in the early 20th century, following unsuccessful attempts to use steam or gasoline power. While on the surface, thesubmarine uses a diesel engine to drive the propeller and generate electricity. When submerged, a battery-driven electrical motor takes over for propulsion...