】: intercontinental missiles with a range of more than 8,000 kilometers. Due to the different geographical locations and operational objectives of different countries, the provisions on the range of intercontinental missiles are also inconsistent. According to the flight trajectory, it is divided into intercontinental ballistic missiles and intercontinental cruise missiles; According to the launching point and international position, it can be divided into ground-to-ground intercontinental missiles and submarine-launched intercontinental missiles. It is an important part of strategic nuclear weapons. Intercontinental ballistic missiles usually use multi-stage liquid or solid rocket engines, inertial guidance or compound guidance, and carry single or multi-warhead nuclear charges (cluster multi-warhead or sub-guided multi-warhead). It has the advantages of large thrust, fast flight speed, long range, high hit accuracy and great destructive power. But most of them are bulky, bulky and inconvenient to maneuver. Land-based intercontinental ballistic missiles are generally deployed in underground silos and launched independently (hot launch) or externally (cold launch). China has developed its own intercontinental missiles.
Is the commodity exchange a futures exchange?
The so-called commodity exchange is an organized fixed market for buying and selling commodity futures contracts at a certain time and place. The futures exchange is a non-profit unit. At present, there are more than 100 commodity exchanges and more than100 international futures exchanges in the world. Other exchanges belong to the domestic market or regional market. In order to adapt to the development of market economy and the needs of export-oriented economy, China began to pilot some commodity exchanges on 1992, and continued to rectify and reduce these exchanges. By the end of 1994, 15 pilot exchanges had been established: Shanghai Metal Exchange, Shenzhen Nonferrous Metals Futures Exchange, Zhengzhou Commodity Exchange, Beijing Commodity Exchange, Hainan Shangzhong Futures Exchange, Guangdong United Futures Exchange, Shanghai Grain and Oil Exchange, Shanghai Commodity Exchange, Suzhou Commodity Exchange, Tianjin United Futures Exchange, Shenyang Commodity Exchange, Dalian Commodity Exchange, Chongqing Commodity Exchange and Chengdu. Changchun United Commodity Exchange was punished by the CSRC for half a year due to illegal operation, and is currently in the stage of suspension and rectification. Although the scale, trading varieties and site layout of domestic commodity exchanges are different, the operating mechanism, functions and management are basically the same. Commodity exchanges only provide trading places for futures traders and act as intermediaries, and do not directly participate in commodity futures trading or the formation of futures prices. Generally speaking, exchanges provide organized trading places and modern service facilities and means for futures trading. There is a large electronic quotation screen hanging in the lobby of the exchange, which can display many changing prices at any time.
What does an honorary doctor mean?
According to the Interim Provisions of the State Council Academic Degrees Committee on Awarding Honorary Doctoral Degrees to Foreign Relevant Persons, China's awarding of honorary doctorates to foreign relevant persons is an honorary title granted by the doctoral degree awarding unit with the approval of the State Council Academic Degrees Committee, aiming at commending outstanding foreign scholars, scientists or famous politicians and social activists who have made outstanding contributions in academic, economic, educational, scientific, cultural and health fields, as well as social development and human progress.
The honorary doctorate in China should generally be awarded according to the disciplines stipulated by China; If necessary, they can also be collectively referred to as "honorary doctors".
What is cloud computing? What are the current applications?
The basic principle of cloud computing is that by distributing computing on a large number of distributed computers instead of local computers or remote servers, the operation of enterprise data centers will be more similar to the Internet. This enables enterprises to switch resources to required applications and access computers and storage systems as needed.
"Cloud" is a computer cluster, and each cluster includes thousands or even millions of computers. The advantage of "cloud" is that the computers in it can be updated at any time.
How many meanings does the wind tunnel principle have?
In fact, the wind tunnel is a device that can create a certain speed of airflow according to the needs and conduct various aerodynamic simulation tests in it. Wind tunnel is widely used in aviation, meteorology, engineering and other fields.
According to the airflow speed, wind tunnels can be divided into low-speed wind tunnels, high subsonic wind tunnels and transonic, supersonic and hypersonic wind tunnels. According to the working mode, the wind tunnel can be divided into continuous working wind tunnel and temporary impact wind tunnel; According to the structure, it can be divided into open and closed.
Wind tunnel usually consists of contraction section, experimental section, diffusion section and measurement control section. Meteorological applications generally belong to low-speed wind tunnels, including instrument verification wind tunnels, cloud experimental wind tunnels and atmospheric environment simulation wind tunnels. Instrument verification wind tunnel is used to calibrate and test wind measuring instruments and study their dynamic performance. Cloud experimental wind tunnel is used to simulate the microscopic process of atmospheric cloud droplet change. At this time, there is also a temperature, humidity and pressure control system in the wind tunnel. The atmospheric environment simulation wind tunnel simulates the meteorological conditions of the atmospheric boundary layer by using the similarity principle, studies the dynamic and thermal characteristics of the boundary layer and their changing laws, and studies the diffusion and migration laws of diffusion in the atmosphere, as well as the influence of terrain and thermal conditions on it. At this time, it is often necessary to set certain terrain features, thermal conditions and smoke tracers in the wind tunnel.
The 0.8m (referring to the cross-sectional dimension of the experimental section of 0.8m× 0.8m) wind tunnel of the Institute of Metrology of China Academy of Meteorological Sciences belongs to a low-speed backflow closed wind tunnel. As the highest level wind speed standard equipment in China, it not only undertakes the transmission of wind speed standard value and wind speed instrument test in meteorological department, but also undertakes the transmission of wind speed value of related instruments in other departments entrusted by the State Bureau of Technical Supervision.
The transmission of the above-mentioned weighed values refers to the step-by-step transmission of the values of the units of measurement reproduced in the national standards to the working measuring instruments through verification, the establishment of a certain value relationship between the measuring standards and the working measuring instruments, and the correction of the measured values of the measuring instruments through this relationship to ensure the accuracy and consistency of the measurement results. In fact, on the other hand, measuring instruments and their measured values can be traced back to national standards within the allowable error range, which is called "traceability" internationally. Therefore, the antonyms of "traceability" and "value transfer" are used to explain the value relationship between measurement standards and working measuring instruments.
The 0.8 wind tunnel of the Institute of Metrology, China Academy of Meteorological Sciences undertakes the task of transmitting the standard value of wind tunnel, which is to transmit the standard value of wind speed to the working anemometer step by step through the first-class wind speed standard authorized by the State Bureau of Technical Supervision and its supporting equipment. The so-called "step-by-step transmission" means that the national meteorological metrology station verifies the wind speed measuring equipment of the provincial meteorological bureau with the first-class standard of wind speed, and the provincial meteorological bureau uses this verification result as the second-class standard to verify the wind measuring instruments used by the county bureau, thus establishing the quantitative relationship between the wind measuring instruments used at the grassroots level and the national standard, providing conditions for the wind measuring instruments to correct their values in business use and ensuring the accuracy and reliability of the measurement results.