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For the existing rubber tree tapping panel coating agent, its carrier film forming properties is not ideal, and there are defects such as easy to be washed by rain, uneven film formation, easy to dry and crack. Six common colloidal preparation carriers, polyvinyl alcohol" 17-88), polyvinyl alcohol 24-88 ), polyvinyl alcohol 22-99H), chitosan, sodium alginate and carboxymethyl-cellulose sodium, were selected to evaluate their viscosity and film-forming properities. The evaluation results show that the viscosity and film-forming properities of polyvinyl alcohol" 17-88 ), polyvinyl alcohol" 24-88 ) and polyvinyl alcohol (22-99H) are relatively good, and are suitable for use as the camer of rubber tree tapping panel coating agent. Among them,polyvinyl alcohol"24-88) carrier is the best,and its concentration is 5 - 10 . The polyvinyl alcohol 24-88 ) caarier has moderate viscosity, easy configuration, uniform film formation, strong adhesion, good folding resistance, and stable mechanical properties. It is an ideal camer for rubber tree tapping panel coating agent. [ABSTRACT FROM AUTHOR]

To meet the need of the teaching experiment reform and innovation of satellite communications, a teaching experiment platform of wideband sateHite communications is constructed based on the practical application. The system is made up of the data source processing units, wideband modulator and demodulator, the noise generator, the multiplexer and the demultiplexer etc, and has the typical intermediate frequency ( IF) transmission link function in the sateHite communication. Through the system, the video signal, the audio signal and the Ethernet data can be the transmitted selectively and flexibly. Besides, the system can implement multi-frequency transmiision with various code modulation schemes by the parameters configuration, and has a good performance even under the low SNR conditions. In the IF section, the noise generator which generates the Gaussian white noise and simulates the SNR variation owing to the power loss is adopted by the system, and the students can understand the important concepts and the key parameters much better in the sateHite communication. Through designing and building the wideband sateHite transmiision system, students can grasp the transmission theories of the new sateHite communication link profoundly and understand the signal processing algorithms thoroughly. The students can also use the modularized platform to develop innovative experiments, which can help students combine the theories with the engineering practice and offer original data for students'scientific research. After the platform has tried out, the quality is significant. [ABSTRACT FROM AUTHOR]