Wednesday, October 13, 2010

GPS positioning world

Pod Defense Department spent 12 billion U.S. dollars into the global positioning system (GPS) application has not limited its military or commercial areas, scientists began using the technology to explore the broader universe of truth.

In ancient times, the location of the sun and the stars position and the time for people to judge the basic identity. October 4, 1957, the former Soviet Union successfully launched the "Voyager" was man-made Earth satellite, then the scientists quickly realized the significance of human satellite is much more than the event itself, because these satellites can be used for global communications or navigation.

Since 1978, the U.S. Rockwell manufactured 24 "Navstar'''satellite continued to climb, a GPS system constitutes the most important part. Each satellite about the size of a truck, around the Earth every 12 hours week, they can ensure the distribution of the sky anywhere on earth who can at any time and at least four satellites to maintain radio contact. GPS system initially used in military field, but later in all participating companies jointly request, start gradually to the commercial and civil sectors. Nowadays people are living in their native place even if you can know the location, the GPS experience the benefits of more and more. now GPS receivers and mobile phones on the same size, and the price is not high . lost the person who hands a GPS receiver, you can at any time and around the earth 24 to contact the Global Positioning System satellites to identify their exact location and exact time.

In addition, a number of GPS users also surprised to find some of its other uses. Astute scientists have discovered, GPS can detect movement and as an excellent tool for observing changes in the world.

If the researchers used GPS receivers to a fixed-point sequential reads data, it can track the movement, such as volcanic lava under the action of the internal swelling, or breaking off from the Antarctic continental shelf on the movement of the iceberg situation. Increase the number of receivers (higher precision), the exact location of the GPS with the known fixed base station signal as a reference, you can clearly capture objects 1 / 10 in. The sudden movement, and its real-time monitoring. With this technology, scientists can "heaven of people to" explore a lot of our original dynamic process is not very clear.

The wind swinging bridge in Hong Kong Tsing Ma Bridge is the world's longest suspension bridge length of 2,200 meters, the main bridge span up to 1377 meters, two crane tower 206 meters, 62 meters from the sea. Bridge can withstand strong typhoons hit, shaking bridge up to a few feet away, but quickly passed the train bridge main span will result in production of about half a meter up and down vibration. However, shaking the bridge can not be too severe, if the bridge side of the trunk put more than 5 meters, the bridge's steel beams and slings noodles would be the same as distorted and bent.

In order to take preventive measures, monitoring of the Tsing Ma Bridge and technical personnel to use the GPS sensor array of three-dimensional position on the bridge for real-time monitoring. They sling the bridge deck and bridge towers installed 14 GPS receiver, the receiver Used cable connected up to several kilometers. These sensors per second will be sent to the central host computer 10 times their spatial location information. While the other two fixed points on the installation of the GPS sensor is also sent back data to the host computer, the host computer to correct the data to reduce the error. This allows the spatial location of the bridge accurately displayed, the level of error of less than 1 cm, the vertical error is less than 2 centimeters. Computer can calculate the wind speed and direction, and all parts of the bridge estimated the stress and load conditions, so that maintenance personnel can easily arrange for repairs and maintenance. Before installing this system, the bridge condition monitoring personnel have also considered other sensing devices, but they currently do not attain this effect. Observed volcanic activity on other planets scientists have never observed the field on the planet Venus or other volcanic eruptions. They only know that in ancient times where there have been volcanic eruptions, but magma flow rate, viscosity and many other circumstances no way of knowing. Venus is now not able to survey the surface of the ground equipment. So scientists can only find on Earth with alternative substances similar study, then the Earth's surface material and the satellite photos were then analyzed satellite photos of other planets, in order to analyze the situation of a distant planet inferred. Earth observation satellite images in the time, scientists have found that two New Mexico up to 40-50 km of the magma flow to them geographer named Car-rizozo and McCartys. Such a long lava flow is rare on Earth, but Venus is a very typical situation. The temperature of Venus is much higher than the earth, magma flow length and retention time longer than on Earth.

The researchers collected information on these two lava flows thousands of copies of GPS data, a lava flow in many different locations, accurate terrain profile information. The magma flows through lots of altitude, slope and other topographical information can help geologists understand the magma viscosity, and thus can determine the composition of magma and the flow speed. Carrizozo and McCartys the middle of these two lava flows of low viscosity, while the periphery is greater viscosity, so the magma flow is characterized by two intermediate velocity, which is difficult cooling, the edge velocity slow cooling speed. GPS data also show that the solidification of the magma shell hidden under a singular phenomenon, including the center of a lava lava flow pipeline, the pipeline allows for up to 15 kilometers of magma from the melting state to maintain. Researchers do not yet know whether that Venus magma pipe, this is a very attractive research content. If there is no high-precision GPS measurement technology, researchers may simply not going to study this issue, the only way to understand this all is to observe personally went down to dangerous places, but even the researchers to stay where a volcanic eruption may not have personally observed Such findings.

Marine barometer of change in the ocean far away from the mainland in more than 60 km in diameter in the great vortex stirring constantly with sea water, deep sea water over the ocean to bring food and nourishment, and the remains of marine organisms volume to the cold, dark bottom. Marine scientists believe that these vortex between marine and terrestrial carbon cycle plays a vital role, but no actual observation data to prove it, because nobody can close the huge whirlpool.

U.S. National Aeronautics and Space Administration (NASA) and the French space agency joint venture construction of Topex / Poseidon satellite altimeter and other research, they can feature on the characterization of vortex fluctuations in surface height measurements.

However, in a distance of 7 km of the sea within, the land of make Topex data chaos. In addition, Topex orbit the earth every 10 days will be a circle, swirl may drift during this time to another location, which has had research inconvenienced. But the GPS does not happen, it can be oriented on the target surface and will not be tracking the impact of the land, but also the state of the global ocean real-time monitoring 24 hours a day.

In order to understand the ups and downs of GPS test the effect of sea water, the researchers of a volcano in the U.S. state of Oregon conducted a series of experiments on the lake. GPS receivers they will be placed in 450-meter-high cliff. Rock cliffs and tranquil lake water into 44 degree angle, so that the receiver readings to provide a wide range of elevation. Sensor to capture the lake reflected GPS signal, then the time and GPS signal transmission line to reach the receiver compares the time, then calculate the height of the water around the lake, the error does not exceed 2.5 cm. In California, the sea near the oil drilling platform also conducted a similar experiment, also achieved good results.

GPS can reveal not only the ocean swirl of mystery. Researchers are studying the use of this technology to monitor global warming caused by rising sea levels. Scientists have generally rely on tide meter for monitoring, but this method only on inshore area changing effective. But the use of GPS system is different, some scientists believe that in the next two to three years on top of the mountain, or tall buildings to install the GPS receiver. This can be very easy on the coast 20 kilometers from the sea outside the continuous monitoring, in addition to access to more accurate data, it can also save a lot of funding.

Early warning systems earthquake seismologists commonly used instrument, the ground tilt meter, strain gauges and other equipment to monitor the earth's crust slightly shaking and rolling, in order to provide early warning of earthquakes. However, these instruments can only be monitored to those faster (in minutes or a few seconds) and the obvious shock, not able to predict the earth's crust after a few weeks or months, a slight earthquake shock. Geographical Survey Institute of Japan now use a system called Geonet to collect this type of early warning data, the system is a distributed all over the country composed of more than 1000 GPS receivers geographic information network. These sensors placed an average of one every 40 km, the distribution of unstable regions in the crust to be more intensive number. Each GPS receiver are placed in the 4.5-meter stainless steel column, the receiver is also equipped with a once every 30 seconds to capture the satellite signal receiving antenna. Data obtained from the sensor can calculate the amplitude level of the crust is less than O. 25 cm of movement, so Geonet other methods can not be detected to detect the small vibrations.

Geonet recently detected near Nagoya, Japan's fourth largest abnormal crustal movement. Nagoya is the Philippine plate with the Eurasian plate subduction zone west of the city's surface each year about 2.5 cm offset. From January 2001 began, the city began with the same speed in the opposite direction of migration. If this phenomenon occurred in a relatively short period of time if a strong earthquake could erupt at any time. This phenomenon is a dangerous signal, but for the study of plate movement for geographers, it is a very useful material. While it is not sure what will happen next, but at least this GPS system to raise awareness of the problem. Summary of GPS system cost by the U.S. Department of Defense established 12 billion U.S. dollars, which is designed mainly for military field, but was forced from the GPS device design manufacturing company, the pressure, the U.S. Department of Defense agreed to GPS systems for business. First operational satellite launch in 1978, 1993, all 24 satellites are already in place. GPS systems in many areas now have access to a wide range of applications, its functionality is now not limited to personal information to provide the location and time. Have this technology, we have the truth of the universe a further step. GPS system of the future is promising to bring the dream of technological progress is endless.

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