No abstract

In order to restore the image in dust environment, a method was proposed to restore the images in dust environment based on a single still image. Firstly, an image degradation model considering multiple scattering factors caused by dust was built using the first-order multiple scattering methods. Then, a new geometric depth model of single image was presented. This model utilized depth map of a dust image to improve usual geometric depth model. According to the new model the every distance of the objects in dust environment was able to acquire from a single still image. Finally, an image in dust environment could be restored according to the relationship between the dark channel prior model and the distance information which was calculated by the geometric depth model. The experimental results have shown that the method enhanced luminance and contrast. The method provided a foundation for target recognition in the dust environments.

In this work, Bi2Fe4O9superfine particles were prepared by hydrothermal method and effects of hydrothermal conditions on the microstructure of Bi2Fe4O9, especially the concentration of OH-([OH-]) in initial solutions, were investigated. The results showed that [OH-] had obvious influences on the growth of Bi2Fe4O9under the same hydrothermal temperature and hydrothermal time. Phase structure of Bi2Fe4O9unchanged with the increase of [OH-] and maintained orthorhombic structure. Besides, the microstructure of Bi2Fe4O9was carefully studied through transmission electron microscopy (TEM). The results suggested that the mechanism of Bi2Fe4O9growth was Ostwald ripening. In conclusion, Bi2Fe4O9superfine particles with good morphology and microstructure can be successfully synthesized when the concentration of OH-is 2 mol/L and hydrothermal conditions are 240 °C for 6h.Keywords: Bi2Fe4O9, hydrothermal method, phase structure, growth mechanism Topic code numbers: C2

In this work, an alternative approach to synthesize (K,Na)NbO3 (KNN) particles is investigated. KNN hydrate particles were prepared by hydrothermal method in a mixed alkaline solution with different KOH/(KOH+NaOH) ratios , and phase structure as well as surface morphology of these niobate hydrate particles were systematically studied. For the reaction rate of Na+ is faster than K+, a mixed alkaline solution with K+/Na+ changing from 4/1 to 5/1was required as a starting solution so a to obtain KNN hydrate particles with K/Na=1. Besides, the results show that particle size of KNN hydrate particles synthesized in different starting solution is dependent on K+/Na+ of the starting solution, and grain size of as-sintered KNN ceramics through hydrothermal method decreases sharply.