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The aim of this paper is to construct a new numerical scheme for the nonlinear gray radiative transfer (GRT) equations, namely, the asymptotic-preserving (AP) $$H_N^T$$ H N T -based unified gas kinetic scheme (UGKS). The constructed scheme is obtained by combing the UGKS for spatial discretization with the hybrid $$H_N^T$$ H N T method for angular discretization. Since the $$H_N^T$$ H N T is a hybrid angular discrete method of both $${P_N}$$ P N and $${S_N}$$ S N methods, the current $$H_N^T$$ H N T -based UGKS can not only mitigate the ray effects of the $${S_N}$$ S N method largely, but also suppress the oscillations of the original $${P_N}$$ P N method. Furthermore, we show that the current $$H_N^T$$ H N T -based UGKS also inherits the AP property of UGKS. A number of one-dimensional and two-dimensional numerical experiments are presented that validate the performance of the current scheme in both optically thin and thick regimes, as well as in mitigating the ray effects. Moreover, it can capture the initial layer solution without requiring additional treatments. [ABSTRACT FROM AUTHOR]

Targeted at a composite material with a novel Ti-555 high-strength titanium alloy matrix developed using the method of "reinforcement wet grinding-spark plasma sintering-heat treatment", a study is conducted on the machining performance during the machining process. Orthogonal experiment method, single factor experiment comparison method and empirical model analysis method are adopted to explore the pattern of changes in cutting force, surface roughness and the wearing of cutting tools under different parameters. There are a number of points revealed by the experimental results as follows. In the machining process, due to the high-strength and hardness of the composite material with Ti-555 high-strength titanium alloy matrix, the selection of machining parameters is limited, and the highest machining speed reaches up to merely 45 m/min. Most affected by the depth of machining, the cutting force increases as machining depth and feed rate are on the rise. The empirical model of cutting force is constructed using the least square regression method, the level of significance is high as indicated by the F test method. and feed rate will make difference to surface roughness. Not only will a greater feed rate increase roughness value, it will also aggravate the wearing of the tool. [ABSTRACT FROM AUTHOR]

In violent vehicular crimes, the damaged area of a vehicle is usually repainted artificially in order to conceal the evidence. Detecting and recovering the hidden sub-layer morphology of repainted automotive paint is highly valuable for providing trace evidence in hit-and-run cases. Optical coherence tomography (OCT) is a novel forensic imaging technique for repainted automotive paint analysis with the advantages of non-destructive, noncontact, high-resolution and cross-sectional imaging. In this study, we applied a custom-built spectral-domain OCT configuration with ~6 μm axial and lateral resolution to obtain three-dimensional (3D) images of an artificially prepared, internally-damaged, repainted automotive paint surface. Two-dimensional (2D) cross-sectional images were produced to locate the damaged area and 3D-OCT reconstruction was performed to directly visualize the sub-layers beneath the repainted paint surface. The results demonstrate that 3D-OCT technology manages to recover high-resolution sub-layer images of the repainted automotive paint through volumetric imaging, and thus provides more valuable information for forensic purposes. [ABSTRACT FROM AUTHOR]

4-(Chloromethyl) phenyltrichlorosilane was used to modify silica spheres to obtain a sensitive and selective nanoparticle powder for detecting latent fingerprints. Various analytical techniques were used to characterize the nanoparticles and to show that the structure and properties are well-suited for forensic science. The synthesis of the particles was optimized based on the performance in terms of detection and the development of a test set of latent prints. The new material offers simple synthesis, convenient use for routine casework, and low price. These advantages suggest potential application for crime scene investigations. [ABSTRACT FROM AUTHOR]