This study investigates the effects of laser power, scanning speed, and powder feeding rate on the aspect ratio of the cladding layer using TC4 powder as the feedstock. A mathematical model correlating process parameters with the aspect ratio is established based on response surface methodology, and optimal process parameters are determined. The results show that the laser power and powder feeding rate had great influence on the aspect ratio of cladding layer. The aspect ratio of cladding layer is proportional to the laser power and inversely proportional to the powder feeding rate. The optimized laser cladding parameters found to be a laser power of 2 500 W, scanning speed of 14.42 mm/s and powder feeding rate of 0.6 r/min. Verification experiments showed good macro-morphology quality of the cladding layer, with a prediction error of only 3.7% when compared to actual values.

The effects of laser cladding process parameters on the microstructure and corrosion resistance of the laser cladding layer with concave pits on the surface of TA1 titanium plate were studied using scanning electron microscopy (SEM) and strong acidic solution corrosion tests. The results show that high or low laser power, slow or fast scanning speed may lead to an increase in defects such as micro pores and microcracks in the laser repair layer. Moreover, higher laser power and slower scanning speeds tend to escalate the corrosion severity of the cladding layer and magnify the morphological difference from the substrate area. To optimize the quality of the microstructure and corrosion resistance of the laser cladding repair layer, a TA1 repair layer prepared with a laser power of 1 800 W, scanning speed of 10 mm/s, spot diameter of 3 mm, and powder feeding rate of 2.5 r/min demonstrated favorable microstructure and corrosion resistance.

A laser cladding coating with good shape and excellent properties was prepared on 42CrMo steel by fiber laser in this study. X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and wear testing machine were used to study the microstructure, phase type, chemical composition, and wear resistance of the coating. Results show that the phases of Fe-based coating are mainly composed of α-(Fe,Cr), γ-Fe, large-plate M7C3 and long-strip M23C6. The wear rate of coating reaches 1.83×10-6 mm3·n-1·min-1, which is 3.6 times lower compared to the matrix, indicating that the wear resistance of the coating is significantly improved. The wear mechanism of coating mainly includes abrasive wear and oxidation wear.

The present study employed an XL-F2000W fiber laser to prepare Ni/WC alloy coatings of varying mass fractions on the surface of 316L stainless steel using laser cladding technology. The cladding coatings' microstructure, hardness, and corrosion resistance were assessed and analyzed through optical microscopy, microhardness testing, and an electrochemical test station. The results show that the cladding coating obtained by the experiment has good metallurgical bonding, uniform and compact structure, and no defects such as hot cracks and pores. The average hardness of the cladding coating exceeds the matrix's hardness by more than 2.2 times and progressively increases with rising WC mass fractions. Furthermore, when the WC mass fraction reaches 40%, the cladding coating demonstrates optimal corrosion resistance.

This study explores the selective laser melting (SLM) of TC4 specimens, focusing on the comparison of variable layer thickness fabrication to fixed layer thickness specimens. The forming method of variable layer thickness fabricating was proposed and the superposition method of variable layer thickness was designed to explore the difference between the forming quality of variable layer thickness specimens and fixed layer thickness specimens. The research shows that the density of the specimen formed by 200 μm → 200 μm → 100 μm→ 100 μm→ 100 μm → 50 μm → 50 μm → 50 μm → 50 μm forming mode is higher than that of the specimen with 200μm layer thickness, reaching 99.13 %, and the building rate is 2.054 mm3/s, which is faster than that of the specimen with 100μm layer thickness. The surface roughness of this forming mode is 14.2μm, which is close to that of the 50μm thickness samples. The tensile strength of the variable thickness specimen can reach 1047.76 MPa, and the elongation can reach 6.18 %. The tensile fracture morphology of the variable thickness specimen is similar to that of the 50μm thickness specimen. Microstructure analysis revealed that the variable thickness specimens possess compact acicular martensite α′, and their tensile fracture morphology resembles that of the 50μm thickness specimen. The findings demonstrate the potential of variable thickness forming as a novel method in SLM formation, offering improvements in forming quality and rate under certain conditions, thus enabling the realization of high-quality and high-speed SLM-formed specimens.

Objective：This study proposes a novel method to address the issues of low efficiency, low accuracy, and low automation prevalent in manual measurement of diameter level and wall thickness of raw bamboo. The method utilizes a pulsed line array laser camera and is based on the OpenCV image processing library and encoder principle. Methods：Firstly, the median filter is used to reduce the noise in the collected bamboo tube images; then, the global threshold segmentation method is used to separate the background and the texture information of the inner wall of the bamboo tube, and the cross-section profile of the bamboo tube is extracted by the Canny operator; finally, the diameter of the bamboo tube and the wall thickness dimensions of the bamboo tube are obtained by calculating based on the coordinates of the pixel points of the extracted profile. Results：The experimental results show that for 12 different sizes of bamboo tubes selected arbitrarily, the accuracy of this algorithm reaches 95.12% and 93.25% for the diameter and wall thickness measurement results, respectively, while the average measurement time is 810 ms, which is much better than manual measurement. Conclusion ：The machine vision-based detection method for moso bamboo′s diameter grade and wall thickness can satisfy required accuracy levels and enhance measurement efficiency, providing a theoretical foundation for the replacement of manual inspections with machine vision technology.

This research focuses on developing a low elastic modulus porous material that aligns with human bone structure and mechanical requirements. The material was developed using Ti6Al4V powder and selective laser melting technology, reflecting the properties of compact and cancellous bones. A model was established by imitating the porous structure of cancellous bone and achieving a porosity rate of 44.92%, following the principle of density similarity to compact bone. The influence of different energy densities (50 J/mm2, 51.8 J/mm2) and pore sizes (500 μm, 1 000 μm, 1 500 μm) on the relevant properties of the porous material was studied. The results showed that the bulk porous structure material prepared based on the above conditions had good formability, uniform and controllable pore size, unobstructed pore channels, controllable dimensional accuracy. The porosity rate increased with the increase of pore size, and the pore size of 500 μm was closer to the design porosity rate parameter. As the pore size increased, it was positively correlated with the tensile strength, but the elastic modulus gradually decreased. The formed quality of the solid part was good, and the tensile test fracture indicated that there were basically no stress defects such as cracks. There were varying degrees of shrinkage pores after melting in all samples, which was a natural characteristic of powder melting and solidification. The porous structure can achieve the design requirements of low elastic modulus, and the sample formed at an energy density of 51.8 J/mm2 reached a tensile strength of 70 MPa and an elastic modulus of 18 GPa at a pore size of 500 μm, which was closer to the performance of human compact bone.

Considering the high temperature gradient and rapid cooling rate in selective laser melting technology (SLM) forming process, this paper initially expounds the time consuming and consumption problems of heat treatment method in solving residual stress, deformation, pore defects and other properties. Based on the potential advantages of remelting scanning in SLM process, the similarities and differences of forming performance between initial scanning and remelting scanning were systematically studied. Based on the 3D surface morphology and surface roughness, the surface quality of Ti6Al4V alloy under initial scanning and remelting scanning was analyzed. In combination with the internal pores, the internal quality differences and similarities of Ti6Al4V alloy under initial scanning and remelting scanning were analyzed. The similarities and differences of microstructure and mechanical properties of Ti6Al4V alloy under initial scanning and remelting scanning were analyzed in combination with microstructure and tensile properties. The results show that the microstructure of the upper surface is martensitic needles α′, and the microstructure of the side surface is columnar grains β, and these columnar grains β pass through the multilayer solidification layer. However, the breadth of these columnar grains β varies between the two scanning methods. Additionally, the tensile strength of remelting scanning is better than that of the initial scanning. In the fracture morphology of remelting scanning, the microstructure becomes larger and the number of dimples decreases.

Aluminum alloy is often used as raw materials for automotive panels and load-bearing components due to light weight, high strength, easy processing and many other advantages. However, impurities and oxide films on the aluminum alloy surface significantly influence the quality of welded joints. This study examines the effect of laser cleaning prior to welding on the laser welding quality of 6061 aluminum alloy. The results show that, under the cleaning process of 300 W-2.5 kHz-2500 mm/s, the oxide film and oil stain on the surface of aluminum alloy can be completely removed without damage to the substrate. In comparison to joints welded without cleaning treatment, the cleaned versions exhibited continuous and smooth weld formations, with virtually no internal pore defects. Furthermore, joint tensile properties showed considerable improvement, with tensile strength reaching as high as 257 MPa.

In order to study the process and quality characteristics of laser welding red copper, this paper conducted laser welding on the sample by changing the laser power, welding speed, welding times, and surface treatment method, analyzed the connection quality from the aspect of weld surface morphology and weld width, and detected the temperature rise and resistance of the welding specimen under electricity. The results show that increasing laser power leads to a decrease in welding speed, expansion of weld width, reduction in resistance, and a slower rate of temperature rise. Optimum results were obtained when the laser power was set at 2000 W, the welding speed at 1.25 mm/s, and the number of welds at two. Further enhancement of weld surface morphology was achieved through polishing and blackening the surface. Under these conditions, the weld width was 0.669 mm, the resistance was at 1.645 μΩ, and temperature rose at the slowest rate.

Sinusoidal textured surfaces with different area densities were prepared on the surface of 40Cr material using nanosecond lasers. Then, the friction and wear properties of the textured surfaces were tested on a CFT-I friction machine at room temperature and under oil lubrication conditions. Additionally, finite element analysis was utilized to explore the influence of the texture area density on friction and wear properties. The results indicate that the optimal texture area density under oil lubrication conditions can effectively generate local dynamic pressure effects, increase the wear resistance of the sample, and significantly improve friction and wear performance. The sinusoidal texture with an area density of 25% (width to depth ratio of 2.322) exhibits the best friction performance, reducing the friction coefficient by 20.4% compared to the non-textured sample.

In order to solve the dimensional accuracy of laser circular cutting of laminated materials, this paper uses finite element software to simulate the temperature field of laser circular cutting of aluminum alloy laminated materials and controls the laser movement path and laser parameters through the APDL programming language. The distribution of the maximum temperature at different moments on the upper surface and at different positions in the X-Z profile was analyzed, the law of influence of the laser parameters on the hole position aperture values was studied and the magnitude of the radius compensation was obtained. The results show that the maximum temperature tends to in-crease slowly with time and the diffusion area gradually increases in the upper surface, and the maximum temperature tends to decrease from top to bottom in the X-Z profile. With the increase of laser power and the decrease of moving speed, the entry aperture diameter is larger than the exit aperture diameter, the shape of the aperture shows an inverted cone shape, and it is found that the upper exit aperture is slightly smaller than the down entry aperture. The radius compensation is about 0.22 mm when 4 mm aperture is completed under different laser power and moving speed, which can provide reference for radius compensation of actual laser drilling.

Wenzhou coastal area is rich in wind resources and has natural advantages in the development of wind power new energy. However, the safe operation of Wenzhou power grid is affected by local strong typhoon, high humidity and high salinity in coastal areas and other adverse climate environment. Bolts and wire fittings fail prematurely in the service process. Therefore, the bolt was treated with laser surface strengthening to improve the wear resistance of the material, and the structure, hardness, wear resistance and impact toughness of the material after laser treatment were analyzed. The results show that the microstructure of laser enhanced layer is acicular and lath martensite with the maximum depth of 1 mm. The wear resistance of laser strengthened bolts is improved obviously. Compared with unstrengthened bolts, the weight loss and wear depth of laser strengthened bolts are decreased by 95.37% and 91.37% respectively. The impact toughness of the unreinforced material is 89 J/cm2, while the impact toughness of the laser reinforced material is slightly reduced to 75 J/cm2. The impact toughness of laser reinforced materials still meets the requirements of relevant standards.

Aiming at the problems of low efficiency, low accuracy and low automation in the manual measurement of wall thickness and diameter level dimensions of raw bamboo, a method for the measurement of diameter level and wall thickness dimensions of raw bamboo canes using pulsed line array laser camera and based on the OpenCV image processing library and encoder principle is proposed. Firstly, the median filter is used to reduce the noise in the collected bamboo tube images; then, the global threshold segmentation method is used to separate the background and the texture information of the inner wall of the bamboo tube, and the cross-section profile of the bamboo tube is extracted by the Canny operator; finally, the diameter of the bamboo tube and the wall thickness dimensions of the bamboo tube are obtained by calculating based on the coordinates of the pixel points of the extracted profile. The experimental results show that for 12 different sizes of bamboo tubes selected arbitrarily, the accuracy of this algorithm reaches 95.12% and 93.25% for the diameter and wall thickness measurement results, respectively, while the average measurement time is 810 ms, which is much better than manual measurement. The machine vision-based detection method for diameter grade and wall thickness of moso bamboo can meet the required accuracy and improve the measurement efficiency, which provides a theoretical basis for the use of machine vision technology instead of manual inspection.

Sulfur trioxide (SO3) is a key precursor for the formation of secondary particulate matter in the atmosphere, and its emissions can lead to an increase in smog and the formation of acid rain. In order to meet the monitoring requirements of SO3 emissions from coal-fired power plants, this paper focuses on the optimization of SO3 gas measurement parameters based on tunable diode laser absorption spectroscopy (TDLAS). The spectral numerical simulation is performed using absorption spectral lines of SO3 near 7.323 μm. The interference of SO2 and H2O absorption spectra is suppressed by optimizing the measurement pressure parameter. Considering the chemical properties of SO3, the effect of temperature on the spectral absorbance of SO3 in the presence of H2O is comprehensively analyzed. The study finds that the system had good effects in suppressing interference and measuring SO3 spectral absorbance under 0.06 atm (1 atm=1.01×105 Pa) negative pressure and 340 ℃ heat tracing conditions. The results of this parameter optimization study have important theoretical reference significance for the development of SO3 gas measurement instruments and industrial field applications.

This study introduces an enhanced point cloud registration method to rectify the low registration precision and need for a superior initial input transformation matrix associated with traditional Iterative Nearest Point cloud registration methods. The improved approach integrates block concepts and point cloud plane fitting for feature point extraction. Firstly, the point cloud is partitioned, and the plane fitting and feature point extraction of the block point cloud are carried out by combining the sampling consistency theorem. Secondly, the fast point pair histogram is used to describe the characteristics of point cloud, and the sampling consistency registration algorithm is used for initial registration, which lays a good foundation for fine registration. Precise registration accelerates the iterative closest point algorithm through K-D tree improvement to realize the overall registration of point clouds. The experimental results show that the proposed point cloud registration method improves the registration accuracy by 89.23% and 31.45% compared with the traditional nearest iteration point method on the two test sets. Compared with other point cloud registration methods, the proposed method also has certain advantages.

Aiming at the characteristics of stone point cloud with many noise points, high density and complex surface structure, as well as the long registration time and poor robustness of traditional iterative nearest point algorithm, a stone point cloud registration method based on key point selection and sampling consistency was proposed. Firstly, the stone point cloud data were preprocessed by denoising and downsampling. Secondly, the key points were selected by the Angle of the normal vector neighborhood of the point cloud, and the fast point feature histogram was constructed for initial registration. Finally, the corresponding point pairs are found according to the K-dimensional tree structure and the minimum distance from point to surface, and the wrong corresponding point pairs are eliminated by the random sampling consistency algorithm to complete the final registration of point cloud data. Compared with the SAC-IA+NDT algorithm, the results show that the proposed method is 21.12% faster than the SAC-IA+NDT algorithm, and 47.1% more accurate than the GICP algorithm. It can realize the rapid and accurate registration of stone point clouds, and provides a new scheme for the registration of stone point clouds.

Optical frequency comb provides an ideal light source for high-resolution molecular spectroscopy. Dual-comb spectroscopy relying on two asynchronous optical combs can analyze the optical comb teeth in the radio frequency domain. It has the advantages of wide spectral range, high resolution, high precision, and short measurement times. However, its application in industrial fields is limited due to its high system complexity and susceptibility to environmental noise. This paper explores and enhances frequency comb interference spectroscopy (FCIS) technology based on optical heterodyne detection between a single optical comb and a continuous-wave laser. Through high-frequency electronic devices and high-speed data acquisition system, the single-shot spectral range is expanded to 66GHz (or 0.5 nm), so that it can realize the simultaneous measurement of 660 longitudinal modes within 10 μs. The near-infrared molecular spectra of acetylene and hydrogen cyanide were measured with high resolution. The spectral resolution reaches 50 MHz (0.4 pm) and the spectral precision is 0.3 pm. The experimental results are consistent with the HITRAN database, showing that the system can be used for rapid and high-precision gas spectral measurement and quantitative analysis. This study thus offers valuable insight into advancing high-resolution optical comb spectroscopy technology suitable for industrial gas monitoring.

To investigate the effect of the active ingredients of flavones in Ampelopsis grossedentata (dihydromyricetin and quercetin combined extract) on promoting the wound healing of photoelectric skin injury. Skin of rats and both fibroblasts and keratinocytes from human skin were injured by fractional carbon dioxide laser, respectively. The injured skin of rats and cells were treated by dihydromyricetin and quercetin after the laser injury, and then evaluated for skin wound healing and protein levels (interlukin-6 and tumor necrosis factor-α) of rats, reactive oxygen species fibroblasts, and cell migration of keratinocytes. Flavones in Ampelopsis grossedentata (dihydromyricetin and quercetin combined extract) decreased reactive oxygen species induced by laser injury in fibroblasts and proinflammatory factors (interlukin-6 and tumor necrosis factor-α) in skin, accelerated cell migration of keratinocytes, and promoted wound healing. Dihydromyricetin and quercetin combined extract promotes skin wound healing through inhibiting inflammation in laser-injured skin.