Carbon fibers with different surface structure are obtained by changing the level of anodization, and have the carbon fiber and epoxy resin processed into carbon fiber-resin matrix composite. Relationship between chemical structure of carbon fiber and moisture absorption property of composite in hot and humid environment is studied. The experiments show that the surface activity of carbon fiber increase significantly after anodization treatment, and there are a large amount of increase for oxygen-containing functional groups in fiber surface, in particular to OH which increase from 17.92% to 33.25%. The moisture absorption mechanism differs in varied conditions of heat and humidity, and temperature is an important factor affecting composites hygroscopic property. The higher the carbon surface activity is, the bigger the equilibrium absorbent moisture would be, and the increase of which would cause an obvious decline in inter-level shear strength (ILSS) value of carbon fiber-epoxy composites.
Metallurgical-grade silicon is purified by using electron beam melting (EBM) technology in this paper. The distribution of impurity aluminum in silicon is uneven in ingot preparation, which shows the enrichment trend that from the bottom to the top and from the edge to the centre of the ingot. The content of aluminum is low in marginally place of ingot, and is lower than the detection limit of ICP-AES (1×10-5%). The theoretical analysis on aluminum evaporation is conducted. The relation between volatilization of impurity aluminum and surface temperature of melting silicon and melting time is introduced from Langmuirs equation and Henry law, which indicates that the removal rate of aluminum increase with the rising of the temperature in melt surface and the expanding of the time, the experimental results are in accord with the calculated one.
With the widespread use of watermark in video, audio and image, propose a relational database based watermark embedding and extraction method. The algorithm utilizes the singlemultiple mapping approach to plug in watermark, which scatter the distribution of watermark information and enhance the anti-attack ability of the algorithm. The experiments show that the method enjoys strong robustness to such attacks as tuples resorting, subset selection and so on.
Comprehensive analysis about Kalman filter model of discrete linear system is discussed in this paper. Firstly, the model is established based on the data of similar material model acquired from industrial close-up photogrammetry system. Then, look for solutions by encoding in Matlab platform. Finally, we conclude that the Kalman filter enjoys obvious denoising effect in data processing of similar material model, and the subsidence curve reflects actual situation of the simulation better. Comparing with the Logistic function fitting, the simulated results show that the proposed filtering model is accurate and effective.
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