No abstract

Considering the flexibility, adjustable pore structure, and abundant active sites of metal–organic frameworks (MOFs), rational design and fine control of the MOF-based hetero-nanocrystals is a highly important and challenging subject. In this work, self-assembly of a 3D hollow BiOBr@Bi-MOF microsphere was fabricated through precisely controlled dissociation kinetics of the self-sacrificial template (BiOBr) for the first time, where the residual quantity of BiOBr and the formation of Bi-MOF were carefully regulated by changing the reaction time and the capability of coordination. Meanwhile, the hollow microstructure was formed in BiOBr@Bi-MOF through the Oswald ripening mechanism to separate photogenerated electron–hole pairs and increase the adsorption capacity of Bi-MOF for dyes, which significantly enhanced the photocatalytic degradation efficiency of RhB from 56.4% for BiOBr to 99.4% for the optimal BiOBr@Bi-MOF microsphere. This research broadens the selectivity of semiconductor/MOF hetero-nanocrystals with reasonable design and flexible synthesis.

No abstract

A B S T R A C TThis paper presents a comprehensive study on the complex drill-exit temperature characteristics in the drilling of unidirectional (UD) and multidirectional (MD) CFRPs using a state-of-art microscopy infrared imaging system. For the first time, temperature variation and distribution at drill exit have been revealed in full detail, associated with the CFRP material properties and drilling conditions. Results suggest that the actual drill/CFRP interactions have critical but similar effects on the drill-exit temperatures for UD and MD CFRPs. Specifically, three distinct cutting regions with varying temperature characteristics are evident when the main cutting edge is acting on the drill exit material. In all cases, the temperature distribution features elliptical shape, of which the eccentricity depends on the lay-up sequence and the drilling depth. In addition, the real-time temperature profiles and 2D/3D maximum temperature distribution maps are created with high visualization. With the aid of those findings, the relationships between drilling temperature maxima, their locations and drilling depths have been discovered and temperature effects on drill-exit damages have been elucidated for the first time. MD CFRP is proven more difficult to achieve high drilling qualities at certain fiber cutting angles than UD CFRP due to the associated temperature effects. Such important knowledge enables the identification of the heat affected zones and subsequently informs strategies for reducing the negative temperature effects.

High-precision calibration of binocular vision systems plays an important role in accurate dimensional measurements. In this paper, an improved camera calibration method is proposed. First, an accurate intrinsic parameters calibration method based on active vision with perpendicularity compensation is developed. Compared to the previous work, this method eliminates the effect of non-perpendicularity of the camera motion on calibration accuracy. The principal point, scale factors, and distortion factors are calculated independently in this method, thereby allowing the strong coupling of these parameters to be eliminated. Second, an accurate global optimization method with only 5 images is presented. The results of calibration experiments show that the accuracy of the calibration method can reach 99.91%.

No abstract

No abstract

No abstract