A novel anti-cat-eye effect imaging technique based on wavefront coding is proposed as a solution to the problem of previous anti-cat-eye effect imaging techniques where imaging quality was sacrificed to reduce the retroreflection from the photoelectric imaging equipment. With the application of the Fresnel–Kirchhoff diffraction theory, and the definition of generalized pupil function combining both phase modulation and defocus factors, the cat-eye echo formation of the wavefront coded imaging system is theoretically modeled. Based on the physical model, the diffracted spot profile distribution and the light intensity distribution on the observation plane are further simulated with the changes in the defocus parameter and the phase modulation coefficient. A verification test on the cat-eye laser echo power of the wavefront coded imaging system and that of the conventional imaging system at a 20 m distance are conducted, respectively. Simulations and experiment results show that compared with conventional imaging systems, the wavefront coding imaging system can reduce the retroreflection echo by two orders of magnitude while maintaining better imaging quality through defocusing.

BIM (building information model) with its advantages of information integration and excellent visualization effect has created considerable economic benefits and significantly improved work efficiency in construction practice. Although BIM is widely regarded as the future of China's construction industry, there are many obstacles to its application in China. This paper briefly analyzes the application status and main obstacles of BIM in China. At the end of the paper, the author provides some suggestions from different aspects.

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ZrB 2 are widely applied because of some excellent performances; however, ZrB 2 is easily oxidized in the high-temperature air. To reach better Al ( OH )3– Y ( OH )3 composite shell and higher coating ratio on the ZrB 2 particles surfaces, ZrB 2 particles must be adequately dispersed in the ZrB 2 suspension during the coating process. The dispersion of ZrB 2 particles and the influence of dispersion on coating effect of ZrB 2@ Al ( OH )3– Y ( OH )3 core-shell composite particles were investigated. The dispersion of ZrB 2 suspension adding the polyelectrolyte dispersant is better than that of ZrB 2 suspension adding the nonionic dispersant; the dispersant content is 2 vol% of ZrB 2 suspension to reach the best dispersion. The best dispersion is obtained by the ultrasonic dispersion for 10 min. ZrB 2 particles are coated using the dispersant and the ultrasonic dispersion in the ZrB 2 suspension to obtain the better coating effect. The dispersion of ZrB 2 particles is increased with increasing the coating content.

Abstract. Due to some excellent properties of YAG, it is researched and applied widely. The YAG porous ceramics are prepared via the vacuum sintering technology. The results show that a certain relationship is existed between carbon emissions time and increasing temperature speed, increasing temperature speed is faster, carbon emission time is shorter, entire sintering cycle is shorter, which makes porosity similar, but higher compressive strength is shown, therefore, the increasing temperature speed slightly faster is advantageous to the performance of YAG porous ceramics, that is to say the heating rate of 5℃/min. By appearance, porosity, compressive strength performance comparison that carbon emissions at 800℃ is more appropriate, porous ceramic YAG prepared under 1500℃ and 1h shows the white surface, 59.4% porosity and compressive strength of 8.55MPa.