|
Space probe according to the detection of object is divided into lunar probe, probe and interplanetary spacecraft, small body such as a space probe to leave the speed of the earth must be large enough to overcome or get rid of the earth's gravity, realize the deep space flight. The probe orbits the heliocentric elliptical orbit (double-cut orbit) that is tangent to the earth's orbit and the planet's orbit, and may meet the target planet; Increase speed to change the orbit, flew to target the planet can shorten the time in order to ensure the detector fly the double track to the planetary orbits and tangent with the target when the target planets also run to it, must be chosen in the earth and the target planet at a particular moment of relative position detector. Detector can fly around the star, the use of planetary gravitational fields accelerate continuous multiple planets orbit the significant characteristic of space probe is, flying in space for long time, the ground cannot real-time remote control, so must have the ability of autonomous navigation; To fly outside the solar system, away from the sun, solar arrays, and nuclear energy systems; It is necessary to adopt special protective structure to withstand very severe space environment. Landing or walking on the surface of the moon or planet requires some special form of structure
Access control is a system enabling authorities to manage entry to areas and resources inside a given physical facility or computer-based information system. Access control is, the truth is, a typical, everyday phenomenon. For example, a lock over a car door is essentially a sort of access control. The PIN on a bank's ATM strategy is another way of access control. Even nightclub bouncers, browsing front of an door, are another demonstration of (perhaps) a more primitive mode of access control. Using an access control mechanism is very important when persons aim to secure confidential, important, or sensitive information and equipment.
Symptomatic care: baby vaccinated, 24 hours may appear low-calorie, vaccination site appear red and swollen, and the following reaction, is normal phenomenon, parents as long as careful symptomatic care, baby will recover soon.
Self-cleaning filter is a kind of using mesh directly to intercept the impurities in the water, purify water, suspended solids, particulate matter, reduce the turbidity, purify water quality, reduce system dirt, bacteria and algae, corrosion, etc, to purify the water quality and protect the system precision equipment of other equipment to work normally.
New Car Buying Tips--


Copyright ?1998-2017 Technews Corp, All rights reserved
|
