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In order to investigate the removal mechanism of C/SiC composites processed by nanosecond laser, and to obtain a groove width and depth with better consistency, in this study, a nanosecond laser was used to ablate 2.5-dimensional C/SiC composites to explore the influence of laser processing parameters and fibre arrangement on the ablation morphology. The experimental results were analysed based on the finite element simulation. The results showed that the amount of material removed and ablation morphology varied considerably between the start and end of the grooves, and the edge effect was pronounced. In addition, the morphology of the ablated groove was affected by the fibre arrangement direction. The temperature field of the C/SiC composite during laser processing was simulated using finite element software. The simulation results intuitively showed that there was a temperature difference between the start and end of the ablation. Further, the temperature field distribution varied by position. Finally, the ablation removal mechanism for the nanosecond laser processing of 2.5-dimensional C/SiC composites was explored by experimental and temperature field simulation results, and laser scanning parameters were optimized to obtain the groove width and depth with better consistency.

Form grinding is one of the most important finishing processes for obtaining high surface quality gears. Nevertheless, to avoid thermally induced burning and structural change poses a major challenge for this manufacturing technology. Based on the moving heat source model and the superposition principle of heat sources, a comprehensive analytical thermal model for analyzing the heat transfer mechanism of involute gear form grinding was derived. A three-dimensional distribution model of equivalent grinding heat source considering the non-linear distribution of tangential grinding force, grinding parameters, and heat partition ratio was proposed. The FEM (finite element method) simulation of the grinding temperature field was carried out to predict the grinding temperature field using a nested net heat flux equation. Research results have shown that the grinding temperature increases nonlinearly with the rolling angle increasing and the evident peak grinding zone temperature appearing near the tip of the tooth. Through the comparison with the previous experimental measurement results, it is found that the temperature distribution of analytical calculation and numerical simulation agrees well with the measured results.

As an irreplaceable optical ceramic material in energy, aviation, and commerce, sapphire is making a further expansion of its application boundaries. Owing to the anisotropy of sapphire, the material properties analysis in the fabrication process is hard but essential. Hence, aiming at investigating the damage behavior of sapphire with different crystal orientations during machining, the nucleation and propagation of cracks in the orthogonal a, c, and m orientations of sapphire under Vickers indentation were explored experimentally and numerically. Firstly, the indentation morphology and indentation cracks of sapphire with different crystal orientations under different loads were studied based on a Vickers indentation tester. In general, the relative errors of the three characteristic parameters, including the half-length of indentation diagonal, the length of crack, and the maximum depth of indentation, are all within 20% between the simulation model and the indentation test results. Then, the nucleation critical loads of different cracks in sapphire under Vickers indentation are determined on the basis of the ceramic materials’ fracture mechanics theory. The critical load value of the median crack of sapphire in both A- and M-planes is less than 0.1 kgf experimentally and simulatively, while C-plane sapphire is between 1 kgf and 2 kgf. Finally, the stress field, displacement–load curve, plastic piling-up height, and dynamic propagation process during Vickers indentation are analyzed, combining the experimental results with a numerical calculation approach.

Sapphire is widely used as a new generation of optoelectronic chips. In this article, single-sided chemical mechanical polishing (SS-CMP) and double-sided chemical mechanical polishing (DS-CMP) were conducted polishing experiments on sapphire wafers. Polishing pressure, relative rotational speed, and polishing time were investigated on material removal rate (MRR), surface roughness (SR), and parallelism of sapphire wafers under the two methods. The results demonstrate both MRR and SR of DS-CMP are significantly better than SS-CMP under the same parameters. Sapphire DS-CMP can obtain a relatively stable average MRR increment of 14.016 nm/min comparing to SS-CMP and can also obtain better surface quality when subjected to greater polishing pressure. Additionally, the parallelism after SS-CMP is about 3 times that of DS-CMP under one-time processing. Finally, sapphire CMP material removal equations are established empirically and theoretically to demonstrate the exponential equation of nonlinear relationship is more suitable for the material removal of sapphire CMP, and the mean error between the theoretical and experimental results of SS-CMP and DS-CMP is within 10%, providing a quantitative and efficient solution for manufacturing sapphire wafers.

Uneven surface quality usually occurs when grinding welds offline, which results non-uniform stress and then would damage the workpiece. In this paper, the robotic welding seam online grinding system based on laser vision sensor was proposed and built. A weld seam tracking software was developed and the data online interaction method of grinding system based on XML (Extensible Markup Language) file was applied. Firstly, hand-eye calibration model was built to convert data in the robot coordinate system. Then the weld profile information was extracted and stored in the data buffer area, and the coordinates of the robotic grinding point were transmitted through the self-developed weld grinding software. Finally, the vision system and the self-made grinding system were integrated at the end of the robot. The experiments were conducted to verify the reliability and practicality of this system and the proposed data interaction online method.

Bi-defect sites are highly effective for CO 2 reduction (CO 2 RR) to formic acid, yet most catalytic surfaces predominantly feature inert, non-defective Bi sites. To overcome this limitation, herein, tensile strain is introduced on wholescale non-defective Bi sites. Under rapid thermal shock, the Bi-based metal-organic framework (Bi-MOF-TS) shows weakened Bi–O bonds and produced tiny Bi clusters. During electrochemical reduction, these clusters create numerous continuous vacancies, inducing weak tensile strain over a large range of surrounding non-defective Bi sites. This strain enhances *OHCO intermediates adsorption and substantially lowers the reaction barrier. As a result, Bi-MOF-TS achieves a faradaic efficiency above 90% across 800 mV potential range, with an impressive formate partial current density of −995 ± 93 mA cm −2 . Notably, Bi-MOF-TS exhibits a high HCOOH faradaic efficiency of 96 ± 0.64% at 400 mA cm −2 in acidic electrolyte and a high single-pass carbon conversion efficiency (SPCE) of 62.0%. Additionally, a Zn-CO 2 battery with Bi-MOF-TS as the cathode demonstrates a peak power density of 21.4 mW cm −2 and maintains stability over 300 cycles. A large range of inert and non-defective sites in catalysts is a primary factor impeding catalyst activity in acidic CO 2 electroreduction. Here, the authors achieve high HCOOH selectivity and activity in acidic electrolyte by introducing tensile strain to activate inert sites.

Form grinding is one of the most important finishing methods to produce precision gears with high surface quality; however, the generation of high temperatures in the ground zone due to very high energy density induces a complex residual stress field during this process. In the present research, temperature distributions in the workpiece were examined using the finite element method (FEM). The heat generation process was assumed as a three-dimensional distribution of moving heat flux, and different grinding factors, including nonlinear distribution of tangential grinding force, grinding parameters, heat partition ratio along the tooth profile, and triangularly distributed heat source along the contact arc, were considered for thermal analysis. The workpiece temperature field was used as thermal loading in stress calculations, and thermal stresses were determined by thermal elastic–plastic FEM with temperature-dependent material properties and a bilinear kinematic hardening model. Further, grinding forces along the tooth profile were measured using a force dynamometer; surface temperatures were estimated by thermocouples pre-embedded along tooth profile; and surface residual stresses in both grinding direction and tooth profile direction were measured by X-ray diffraction (XRD) analysis. Experimental results of temperatures and residual stresses were utilized to validate the FEM results, and the comparison between numerical and experimental results suggests that the proposed model can be adopted to estimate residual stresses in gear form grinding.

Carrying out supervising of sawing equipment through advanced sensor is an important study in modern automatic sawing technology. The application of monitoring techniques can greatly increase the life of saw blades, lower the cost, reduce the secondary machining, and improve work quality and productivity in sawing. The acoustic emission (AE) monitoring techniques are studied mainly in this paper. Aiming at the advantages such as high sensitivity, wide application range, and good correlation, the basic principles and key technologies of AE monitoring technology are introduced. Then the study status is reviewed in the fields of online monitoring in sawing surface quality, sawing vibration, saw blade conditions, and its application in automation control technology by AE monitoring technology. The disadvantages and future development trend of AE monitoring techniques in sawing are demonstrated.

Background: Congenital diarrhea is persistent diarrhea that manifests during the neonatal period. Mutations in DGAT1, which is crucial for triglyceride synthesis and lipid absorption in the small intestine, are causal factors for congenital diarrhea. In this study, we aimed to determine the value of tissue RNA sequencing (RNA-seq) for assisting with the clinical diagnosis of some genetic variants of uncertain significance. Methods: We clinically evaluated a patient with watery diarrhea, vomiting, severe malnutrition, and total parenteral nutrition dependence. Possible pathogenic variants were detected using whole-exome sequencing (WES). RNA-seq was utilized to explore the transcriptional alterations in DGAT1 variants identified by WES with unknown clinical significance, according to the American College of Medical Genetics guidelines. Systemic examinations, including endoscopic and histopathological examinations of the intestinal mucosa, were conducted to rule out other potential diagnoses. Results: We successfully diagnosed a patient with congenital diarrhea and protein-losing enteropathy caused by a DGAT1 mutation and reviewed the literature of 19 cases of children with DGAT defects. The missense mutation c.620A>G, p.Lys207Arg located in exon 15, and the intronic mutation c.1249-6T>G in DGAT1 were identified by WES. RNA-seq revealed two aberrant splicing events in the DGAT1 gene of the patient’s small intestinal tissue. Both variants lead to loss-of-function consequences and are classified as pathogenic variants of congenital diarrhea. Conclusions: Rare DGAT1 variants were identified as pathogenic evidence of congenital diarrhea, and the detection of tissue-specific mRNA splicing and transcriptional effects can provide auxiliary evidence.