2. no. There is no sound as a medium to spread. If you really want to, you can stick your helmet together and say.
3.
3. In order to increase friction, it is not easy to slip; Increase friction to help brake.
4. Reduce the contact area, increase the pressure and make the clothes perforated.
5. Using the U-tube principle, the structure is U-tube structure.
6. Use the accumulation of evaporated water vapor to increase the pressure in the pot, reduce the boiling point of water, and make cooking easier.
7. The inside of the ship is hollow, and the steel outside sinks into the water, generating enough buoyancy to balance the gravity floating on the water.
8. Use the obtained heat to expand the air inside, so that the overall gravity is reduced, the volume is unchanged, and the buoyancy is greater than gravity, so it rises.
10. Big stones and wooden poles
1 1. Crane belongs to a kind of hoisting machinery, and it is a kind of cyclic intermittent motion machinery. A working cycle includes: the picking device lifts the object from the picking position, then moves horizontally to the designated position to put it down, and then moves reversely to return the picking device to the original position for the next cycle.
Generally, lifting machinery consists of lifting mechanism (to make the goods move up and down), running mechanism (to make the lifting machinery move), luffing mechanism and slewing mechanism (to make the goods move horizontally), plus metal mechanism, power device, operation control and necessary auxiliary devices.
type
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The research of modern robots began in the mid-20th century, and its technical background is the development of computers and automation, as well as the development and utilization of atomic energy.
Since the first digital electronic computer came out in 1946, the computer has made amazing progress and developed towards high speed, large capacity and low price.
The urgent need of mass production has promoted the progress of automation technology, and one of the achievements is the birth of 1952 CNC machine tool. The research on control and mechanical parts related to CNC machine tools laid the foundation for the development of robots.
On the other hand, the harsh environment of the atomic energy laboratory needs some operating machinery to deal with radioactive substances instead of people. Under this demand background, the argon research institute of the American Atomic Energy Commission developed a remote manipulator in 1947 and a mechanical master-slave manipulator in 1948.
1954, American Deval first put forward the concept of industrial robot and applied for a patent. The main point of this patent is to control the joints of the robot with the help of servo technology, and teach the robot with hands, so that the robot can record and reproduce actions. This is the so-called teaching and reproducing robot. Almost all existing robots adopt this control method.
The earliest practical models (teaching reappearance) as robot products are "VERSTRAN" introduced by AMF Company of the United States in 1962 and "Unite" introduced by UNIMATION Company of the United States. The control mode of these industrial robots is similar to that of CNC machine tools, but their appearance characteristics are quite different, mainly composed of humanoid hands and arms.
1965, Roborts of MIT demonstrated the first robot system with visual sensor, which can identify and locate simple building blocks.
1967, Japan established the prosthetic hand research society (now renamed the bionic machinery research society), and in the same year, the first robot society in Japan was held.
1970 the first international conference on industrial robots was held in the United States. After 1970, the research on robots has been rapidly and widely popularized.
Cincinnati 1973? Richard from Milla Cloning Company? Horn made the first industrial robot controlled by a small computer. It is hydraulically driven and can lift 45 kilograms of payload.
It was not until 1980 that industrial robots really became popular in Japan, so it was called "the first year of robots".
Subsequently, industrial robots have been greatly developed in Japan, and Japan has won the reputation of "robot kingdom".
With the rapid development of computer technology and artificial intelligence technology, the function and technology of robots have been greatly improved, and the vision and tactile technology of mobile robots and robots are typical representatives. Due to the development of these technologies, the concept of robot has been expanded. In 1980s, the system with the ability of feeling, thinking, decision-making and action was called intelligent robot, which is a general and extensive concept. This concept not only guides the research and application of robotics, but also gives robotics a huge space for development in depth and breadth. Underwater robots, space robots, aerial robots, ground robots, micro-robots and other robots with various purposes have come out one after another, and many dreams have been realized. Robot technology (such as sensing technology, intelligent technology, control technology, etc. ) has been diffused and infiltrated into various fields, forming a variety of new machines-robot machines. At present, the interaction and integration with information technology have produced the names of "software robot" and "network robot", which also shows the innovative vitality of robots.
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14. Get speed and use inertia.
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16. Lanterns are colorful and neon lights are flashing. More and more cities in China have colorful night scenes. However, night lighting not only beautifies the city, but also brings some adverse effects to the life of urbanites. There are no stars over the city, dazzling lights make people nervous, and artificial sunlight makes it difficult to sleep. Urban construction and environmental protection experts remind that while the city lights up, with light pollution, the practice of "only pursuing brightness, the brighter the better" will bring unpredictable harm.
Light pollution is generally divided into three categories in the world, namely white light pollution, artificial sunlight pollution and colored light pollution.
White pollution When the sun is strong, the glass curtain wall, glazed tile wall, polished marble and various paints of buildings in the city reflect light, which is bright and dazzling. Experts have found that people who work and live in an environment polluted by white light for a long time will suffer different degrees of damage to their retina and iris, and their vision will drop sharply. The incidence of cataract is as high as 45%. It can also make people dizzy and upset, and even cause insomnia, loss of appetite, depression, physical weakness and other similar symptoms of neurasthenia.
In summer, the strong reflected light from the glass curtain wall enters the nearby residential buildings, which raises the indoor temperature and affects normal life. Some glass curtain walls are semi-circular, and the convergence of reflected light is easy to cause fire. Drivers driving in the hot sun will suddenly be attacked by the reflected light from the glass curtain wall, and their eyes will be strongly stimulated, which is prone to car accidents.
After the arrival of artificial day and night, the advertising lights and neon lights in shopping malls and hotels are dazzling. Some intense light beams even go straight into the sky, making night like day, which is called artificial day. In such a "city that never sleeps", it is difficult to fall asleep at night, which disturbs the normal biological clock of the human body and leads to low work efficiency during the day. Artificial sunlight can also harm birds and insects, and strong light may destroy the normal reproduction process of insects at night.
Color light pollution The black lights, rotating lights, fluorescent lights and flashing color light sources installed in dance halls and nightclubs constitute color light pollution. According to the measurement, the intensity of ultraviolet rays produced by black light is much brighter than that in sunlight, and the harmful effects on human body last for a long time. If people receive this radiation for a long time, they will cause nosebleeds, tooth loss, cataracts, even leukemia and other cancers. The dazzling color light source is not only bad for the eyes, but also interferes with the central nervous system of the brain, making people dizzy, causing nausea, vomiting, insomnia and other symptoms. The latest research by scientists shows that colored light pollution not only damages people's physiological functions, but also affects people's mental health.
17. Convex lens imaging