In this study, specimens composed of high-strength 316L-CuSn10 multimaterial were fabricated utilizing the laser selective melting technique. An interrupted interlaminar scanning strategy, implemented at interfacial junctions for durations of either 30 seconds or 60 seconds, was employed. The influence of varying interruption times on interfacial bonding properties was systematically examined. The empirical findings revealed that the interrupted interlayer scanning strategy effectively widened the bonding layer at the steel-copper interface. Additionally, it facilitated elemental intercalation at the interface, leading to a reduction in micro-zonation compositional differences. Consequently, metallurgical bonding at the interface was notably augmented. The ultimate tensile strength of specimens subjected to the 30-second interruption scanning strategy reached an impressive 501.0 MPa±27.4 MPa, while the bending strength peaked at 1 013.1 MPa. These values demonstrated a substantial improvement compared to the strength of single-material specimens. The tensile fracture analysis indicated a mixed fracture mode at the interface transition zone, combining both ductile and brittle fracture characteristics. The intermittent scanning strategy represents an innovative approach for shaping multi-material components with diverse performance attributes and achieving high-quality outcomes. This research contributes valuable insights into advancing the fabrication of materials with enhanced mechanical properties.

In this study, the single-factor experiment was used to detect the roughness, observe the three-dimensional surface morphology, SEM morphology and density of GH3625 specimen with different selective laser melting（SLM) forming process parameters. The results show that within the experimental range, the upper surface roughness initially decreases and then increases with increasing laser power, scanning speed, scanning spacing, and scanning layers. Increased exposure times enhance cross-fusion between fused regions, slightly raising the surface roughness. Remelting, facilitated by higher scanning times, promotes the convergence of convex and concave surfaces, yet excessive remelting leads to repeated surface heating and elevated roughness. Optimum conditions of 168 W laser power, 600 mm/s scanning speed, 0.09 mm scanning distance, 2 scanning layers, and 2 exposure times yield a minimum upper surface roughness of 2.11 m for GH3625 alloy, accompanied by a columnar and hexagon-like cellular microstructure and a final product density of 98.6%.

This paper explores the application of selective laser melting (SLM) technology in the fabrication of innovative porous bone scaffolds, highlighting the advantages of such scaffolds in terms of designability and mechanical properties. Three types of regular cellular structures, VC (cylindrical connecting rod cube), SHC (spherical pore cube) and FCC (face centered cube), are constructed. Through finite element analysis of the relationship between the corresponding characteristic size, porosity and elastic modulus, the mathematical model between the characteristic size, porosity and elastic modulus of the three single cell models is established. It is clear that the three cell structures are suitable for the structural design of femur scaffolds within the optimized characteristic size range. In addition, SLM technology is used to print the 316L 5×5×5 lattice structure with the corresponding feature size cell as the primitive. The simulation results are verified by quasi-static compression test. Experimental results show that the average error between the actual and simulated elastic modulus of lattice structures with corresponding feature sizes is 14.8%, and the error decreases with the increase of the physical size of the structure, in which the single cell structure sizes are VC: r∈［0.28 mm, 0.32 mm］, SHC: d∈［2.24 mm, 2.36 mm, FCC: The lattice structure printed under the condition of R∈［0.20 mm, 0.24 mm］ meets the use requirements of femur scaffolds.

In order to obtain the process parameters of selected laser melting (SLM) 316L stainless steel suitable for grinding, an orthogonal experiment with three factors and four levels was designed. On this basis, the experimental data of the performance index density, microhardness and surface roughness after grinding were obtained, and the main and secondary effects of SLM process parameters on the performance index were obtained by range analysis method. Based on grey correlation theory, the experimental data were simplified by multiple indexes to obtain the quantified value-correlation degree, which can evaluate the comprehensive performance of the sample. The regression equation of process parameters and correlation degree was obtained by fitting regression method. The fitting degree of the equation reached 91.32%, indicating that the equation has high reliability. Using Minitab to optimize the regression equation, the optimal process parameters suitable for grinding were obtained as follows: laser power 270 W, scanning speed 707 mm/s, scanning spacing 0.14 mm, The density was 98.78%, the microhardness was 265.46 HV, and the surface roughness was 0.66 m.

Laser cladding deposition is a crucial technology for surface modification and 3D freeform fabrication, with process parameter selection significantly influencing the geometry and mechanical properties of the melt channel. This study employs the response surface analysis method to develop a mathematical model correlating process parameters—laser power, scanning speed, and wire feeding speed—with responses such as melt height, aspect ratio, dilution rate, and microhardness in an annular focus laser coaxial cladding deposition process. The results show that the scanning speed is the most significant factor affecting the height of the melt channel, aspect ratio and microhardness, and the laser power is the most significant factor affecting the dilution rate. The expected combination of process parameters was obtained by synchronous optimization method, and the predicted results were in good agreement with the experimental results, and the average relative errors of melt height, aspect ratio, dilution rate and microhardness were 8.33%, 1.67%, 2.50% and 1.71%, respectively. Using the process parameters calculated by the model, a variable-diameter thin-walled part with a height of 100 mm is formed. The dimensional accuracy of the formed parts is high, the structure is dense and uniform, and there are no obvious defects such as pores and cracks.

This paper addresses the challenge of high-performance repair for thin-walled aeronautical TC1 structures by investigating the pulsed-laser additive manufacturing process for repairing thin sheets and lattice structures. The repair quality was assessed through microstructural and macrostructural analyses, as well as tensile tests on TC1 sheets and compression tests on aeronautical lattice structures. The results showed that the repair area shows good metallurgical bonding with the substrate under the conditions: laser power of 600~1 000 W and pulse time of 100 ms. Higher volume fraction of finer ′ martensite structure can be obtained, becaused of the high temperature gradient during the repairing process by a pulsed laser. Moreover, the tensile strength and yield strength of the thin plate specimen after laser repairing are slightly higher than those of the forged specimen, while the elongation decreases to a certain extent. When subjected to simulated compression test, the maximum average damage force of the sample after pulse repairing is increased from 2.5 kN to 3.58 kN.

To enhance the surface properties of 45 steel, a self-designed Fe-Cr-Ni alloy powder was utilized to fabricate a well formed Fe-based alloy coating via laser cladding. The microstructure and phase composition of this coating were thoroughly examined, and its wear resistance and high temperature oxidation resistance were evaluated. The results show that the microstructure of laser cladding Fe based alloy coating is uniform and compact, there are no obvious defects such as cracks and pores, and the main phase is -Fe、-(Ni-Cr-Fe)、-(Fe, Ni)、-(Fe-Cr) and Fe0.64Ni0.36 intermetallic compounds; The hardness of the cladding layer reaches 720 HV, about 3.3 times of the matrix; Through the dry sliding friction and wear test, the friction coefficient of the cladding layer is 0.57, which is lower than that of the matrix. The wear volume of the cladding layer is 0.01 mm3, which is 18.8% of the average wear volume of the matrix; After 100 h high-temperature oxidation, there was no peeling of oxide film on the cladding layer. At 500 ℃, 700 ℃ and 900 ℃, the oxidation weight gain was 2.19 mg·cm-2, 5.11 mg·cm-2 and 6.61 mg·cm-2 respectively.

The medium-Mn steel (0.1%C-5%Mn-Fe), renowned for its exceptional balance of high strength and ductility, has garnered significant attention in the automotive industry as a promising material for next-generation automotive steel. The medium-Mn steel was joined with fiber laser, and formability of the welded joint was carried out with the Erickson cupping test machine. The factors affecting the cupping test performance of the joint were analyzed with finite element simulation, and the cupping test results were compared with those of gas tungsten arc welding. The results show that "hardening zone" is formed in welded joint, which reduces the formability of the welded joint. The width of the HZ is one of the primary factors affecting the formability of the welded joint, and the narrower the hardening zone is, the better the formability of the welded joint is. The effect of laser welding speed on the width of hardening zone is more obvious, and the formability of welded joint can be improved by reducing the width of hardening zone. In this paper, the forming ratio of laser welded joint of 2 mm thick medium Mn steel can reach 0.66.

This study investigates the laser-MIG hybrid welding of 20 mm thick 6005A-T6 aluminum alloy components for railway vehicles, aiming to optimize welding parameters and achieve high-quality joints. Through optimization of groove dimensions, the use of a U-shaped groove with a root face height of 8 mm and an assembling clearance of 2 mm, coupled with a three-layer and three-pass welding method, yielded optimal results. The microstructures in the weld center and near the fusion line were equiaxed crystal and columnar crystal respectively. Compared with the filling and covering weld zone, the equiaxed crystal size was coarsest and the columnar crystal zone was widest in the backing weld zone. The microhardness of the weld zone and heat affected zone was lower than that of the base metal, and the lowest microhardness was found near the fusion line. Despite this, the average tensile strength of the joints reached 191 MPa, representing 76% of the base metal strength. The samples fractured near the fusion line, and the fracture morphologies generally showed the ductile-brittle mixed fracture features.

In this paper, the finite element method was used to study the thermal cycle, the evolution law of thermal stress-strain and the mechanical mechanism of the fiber laser welding and CO2 laser welded superalloy Inconel 617. The results show that the accuracy of the heat source model for laser welded superalloy Inconel 617 with the rotating body heat source, the rotational body heat source rotational logarithmic body heat source and 3D gauss heat source is good. The cooling rate at the neck shrinkage of the HAZ is the lowest. When heating above 1280 ℃ in the HAZ, constitutional liquation was found inside the grain and at grain boundaries. There was no significant decrease in Von Miss stress of fiber laser welding and CO2 laser welding for superalloy Inconel 617. The first principal strain of HAZ for fiber laser welding is increased gradually, while the first principal strain near the HAZ neck shrinkage in CO2 laser welding is increased significantly. With the decrease of laser welding heat input, the sensitive strain rate of HAZ liquation cracking gradually increased. Compared with the Von-mises stress and the first principal strain of laser welding in HAZ, the liquation cracking sensitive strain rate is more suitable to explain the main factors for the formation of liquation cracking in laser welding of superalloy Inconel 617.

This study scrutinizes the mechanism of femtosecond laser precision micromachining applied to face gear material 18Cr2Ni4WA. A comprehensive hydrodynamic model is proposed to elucidate the solid-liquid and gas-liquid phase transitions, taking into account factors including surface tension, Marangoni effect, buoyancy, gravity, and vapour recoil pressure. The investigation assesses the effects of varying pulse numbers, energy densities, and repetition frequencies of femtosecond laser on ablation crater depth and border morphology through model simulation and experimental trials. Findings indicate that a rise in laser pulse number and energy density enhances crater depth with divergent degrees of ablation crater edge elevation. An increase in laser repetition frequency escalates ablation line groove depth; optimal ablation morphology is identified at a repetition frequency of 300 kHz, while a poorer form is observed at 500 kHz due to increased melt accumulations within the ablation line groove. These insights offer the groundwork for advancing surface topography quality during femtosecond laser micromachining of face gear materials.

To enhance the anti-corrosion and antifouling capabilities of 9 442 copper alloy in marine environment, a nanosecond laser surface treatment was employed to induce a hierarchical micro/nano composite structure, resulting in superhydrophobic surfaces with contact angles exceeding 150°. Electrochemical corrosion tests on these surfaces, treated with varying laser powers, revealed that at 100 W, the corrosion current density decreased to 7.323×10-7 A·cm-2, achieving a 70.0% corrosion inhibition efficiency compared to untreated copper alloy. Additionally, offshore antifouling performance tests demonstrated that the superhydrophobic surface exhibited superior antifouling and corrosion resistance, with minimal component corrosion, highlighting its practical application potential in marine environments.

This paper examines the critical aspects of metallized through-hole quality in low-temperature co-fired ceramic (LTCC) components, focusing on the hole opening and filling processes. The quality of hole opening is fundamental to ensuring the subsequent filling process. The study analyzes the performance of CO2 laser drilling on the white raw material belt of 30-micron-thick LTCC, addressing issues such as local perforation and residual raw ceramic material in the annular drilling mode. A universal and efficient program design method for laser annular drilling is proposed, which significantly improves the quality of apertures larger than 100 m through process enhancement and design optimization.

Glass is the basis of industrial raw materials, and the improvement of its output and quality plays an important role in practical application. How to measure the thickness of glass at high speed and accurately has become an urgent problem to be solved in glass production line. Among many measuring methods, laser ranging has the advantages of high precision, fast speed, non-contact and convenient operation. In this paper, the distance between the laser emitter and the front and rear surfaces of the glass parts to be measured is measured by laser frequency sweep interferometry ranging system, and the thickness of the glass parts to be measured is obtained by calculating the distance difference. Firstly, the beat signal of the distance is obtained, and the beat signal is compensated by interpolation fitting method to realize nonlinear correction. By interpolating the beat signal after nonlinear correction, the number of measured signal points after interpolation is 20 times that before interpolation, and the phase signal becomes smooth. Then, the phase extreme point is selected for phase splicing to increase the number of signal measurements and reduce the influence of spectrum leakage on the experimental results. Finally, the splicing signal is performed by fast Fourier transform to obtain the distance difference between the front and rear surfaces of the glass to be measured, namely the thickness of the glass. The experimental results show that the thickness error of glass without phase splicing treatment is less than 50 m, and the thickness error of glass with phase splicing treatment is less than 15 m. The phase splicing method effectively improves the precision of glass thickness measurement in industry.

This paper investigates the detection of defects in honeycomb sandwich structures, including honeycomb core collapse, adhesive-free areas, and inclusions beneath both aluminum alloy and carbon fiber skins. Employing shearography and the theory of elastic mechanics thin plate deformation, the study compares and analyzes the detection of these defects under negative pressure loading and speckle interference. A normalized out-of-plane displacement index is introduced to examine the correlation between displacement and negative pressure for various defect types. The results show that shearography can be effective at detecting the honeycomb core collapse defects and adhesive-free defects with diameter greater than 10 mm, while it is not good at detecting the inclusion defects with diameter less than 20 mm. Under the same skin, the normalized out-of-plane displacement of honeycomb core defects is 2~5 times that of adhesive defects. This study can provide technical support for the detection and identification of defect types in honeycomb sandwich structures.

In this paper, a method using building information modeling (BIM) data to correct LiDAR erroLrs is proposed to solve the indoor precise positioning problem of building robots. Firstly, probabilistic modeling was carried out for the sampled radar data, and then the significance level of uncertainty variables affecting the positioning accuracy of the robot was studied by using the analysis of variance. After the sensitive variables were determined, BIM information was introduced and combined with the maximum likelihood estimation method to correct the radar data. Finally, the position accuracy of the object scanned by LiDAR is evaluated. The results show that the material error variance across different types is on the millimeter scale, and the proposed correction method effectively mitigates these errors.

Based on the tunable diode laser absorption spectroscopy technology, the absorbance of common hydrocarbon fuels and combustion products in the 3 632~3 650 cm-1 band were simulated, and two pairs of CO2 high-temperature spectral lines with center frequencies at 3 633.08 cm-1 and 3 645.20 cm-1 were selected. A high temperature spectral parameter measurement system was set up by using a three-stage high temperature tube furnace composed of three relatively independent temperature control zones. A stable and closed flow field environment was constructed. The spectral line intensity, self-broadening coefficient and their temperature index, air-broadening coefficient and its temperature index of two spectral lines were measured. The measurement results were compared with the CDSD-HITEMP spectral database. The relative deviation of the air-broadening coefficient of two spectral lines was significantly greater than other parameters, The maximum is 16.32%, and the relative deviation of other spectral parameters is within 13%.

The Ultra-High Voltage (UHV) pillar porcelain insulator, a critical component in power systems, is prone to brittle fracture due to stress concentration and internal cracks, posing safety risks. To mitigate this, real-time load monitoring of these insulators is imperative. This paper presents a novel online load monitoring system for UHV pillar porcelain insulators utilizing laser ultrasonic technology, coupled with an advanced correction algorithm for air and surface wave interference during synchronous excitation. The theoretical foundation for laser ultrasonic stress detection on porcelain insulators is substantiated through simulation analysis. The hardware and software components of the system have been meticulously designed and developed. Experimental results demonstrate the system′s high efficiency in online monitoring, achieving an average error of 16.20% between measured and actual bending loads. This accuracy meets engineering detection requirements, indicating the system′s promising application potential for enhancing the safety and reliability of UHV power systems.

A sub-pixel stripe center extraction method leveraging the Gaussian-weighted grayscale center of gravity and density clustering is proposed. This approach addresses the limitations of traditional strip extraction algorithms, particularly their susceptibility to interference and the need for enhanced efficiency. The proposed method successfully extracts the center line of the light bar for images with noise points. The effective light-stripe information in the image is first extracted using the single channel extraction, gamma correction, and Otsu method. The light-stripe centerline is then initially fitted using the Gaussian-weighted grayscale center of gravity method. Finally, the light-stripe centerline is further accurately fitted using the density clustering algorithm. The method achieves a root mean square error of approximately 0.72 pixels and exhibits a maximum fluctuation of 13.6% under conditions of fewer than 1 000 random noise points. In terms of performance, the proposed method demonstrates a 4.8-fold increase in efficiency compared to the conventional Steger algorithm, with a minimal loss of 9.2% in accuracy.

In the domain of stereolithography (SLA), laser path planning algorithms are pivotal for optimizing the printing process. Traditional methods, which rely on small or simple variable laser spots, often struggle with balancing printing efficiency and quality, particularly when dealing with models that feature long-narrow or thin-walled sections. This paper introduces a novel path planning algorithm that employs a variable spot size, based on the partition-combination concept. The algorithm consists of following steps: For each layer slice, two sizes of laser spots are used to complete pre-scanning process firstly. Then, the filling region is divided into multiple subregions with different spot types. According to the adjacency relationship, the subregions of the same type are merged into larger ones to ensure the scanning continuity. Finally, the merged subregions are filled and generate scanning paths using variable spot. Experimental results indicate that the proposed algorithm enhances the printing efficiency for models A and B by 19.5% and 21.2%, respectively, over single small spot scanning methods, while maintaining comparable formation quality. Furthermore, when compared to simple variable spot scanning methods, the structural strength of models A and B improves by 14.3% and 14.9%, respectively, with only a minimal reduction in efficiency.

In the field of optical surface shape detection, the use of space carrier phase shift technology can realize the rapid and dynamic measurement of the surface shape to be measured, and the introduction of systematic error has always been an important factor restricting its accuracy. In order to solve this problem, this paper proposes a method for adaptive introduction of optimal systematic error. This method realizes the introduction of different carrier amounts for different specifications of the mirror to be tested, controls the system backhaul error within a reasonable range, and improves the accuracy of space carrier surface shape detection, and the process can be summarized as follows: First, estimate the PV value of the mirror to be measured. The default of the plane mirror is 0.3, and the spherical mirror calculates its PV value by obtaining its radius of curvature R and aperture , and substitutes the PV value calculation formula; secondly, the weight of the system backhaul error is equal to the weight of the PV value of the mirror to be measured; finally, the inclination angle of the mirror to be measured is inferred and the number of carrier fringes through the system backhaul error calculation formula, and whether the value range of the number of carrier fringes is judged. Experimental results demonstrate that, compared to the fixed fringe method in traditional spatial carrier techniques, this method improves the detection accuracy of flat mirrors by approximately 10% and the detection accuracy of spherical mirrors by approximately 15%.

This paper presents the application of a self-developed laser-induced breakdown spectroscopy (LIBS) online detection system for the rapid and quantitative analysis of coal combustion parameters, specifically sulfur content and calorific value, which are critical indicators affecting the efficiency of power plant boilers. A total of 57 coal samples from actual production were analyzed, with 43 dedicated to model development and 14 for validation. The system captured characteristic spectra, from which multiple spectral lines corresponding to sulfur, carbon, magnesium, silicon, iron, calcium, hydrogen, oxygen, and nitrogen were selected. Analytical models were initially developed using multiple linear regression (MLR) and subsequently refined with partial least squares regression (PLSR). The combined MLR and PLSR approach yielded superior analytical outcomes, enhancing the precision and accuracy of sulfur and calorific value determination in coal. The models achieved coefficients of determination (R2) of 0.925, 0.951, and 0.951, with average relative errors of 3.16%, 0.67%, and 0.52%, respectively.

The identification and clustering analysis of rock discontinuities are the basis for studying the structural characteristics of rock masses and assessing the stability of rock masses. In order to perform fast and effective clustering of rock body discontinuities, a 3D point cloud-based rock body discontinuity identification and fast clustering method is proposed. Firstly, the point cloud segmentation and plane fitting are performed by FACET to extract the rock body discontinuity surface. Secondly, the local density and control distance are calculated by the similarity distance between the rock discontinuity faces, and the decision map is drawn to find the clustering center and the number of clusters automatically. Finally, according to the boundary density, the rock discontinuities are divided into core discontinuities and outlier discontinuities, and the outliers are eliminated. This method avoids the interference of human subjective factors and improves the accuracy of clustering analysis. Through the clustering analysis of cubic and hexahedral, the number of clusters is consistent with the expectation, and the average yield of each cluster is similar to the fitting results of point cloud discontinuity surface, with the maximum error of dip direction 0.47° and 1.78°, and the maximum error of dip angle 2.98° and 2.57°, respectively. At the same time, the clustering performance is improved to a certain extent compared with K-means, K-means++ and DBSCAN clustering algorithms, up to 0.834. Field application to the discontinuous surface of a high, steep cliff in Huidong County, Sichuan Province, demonstrates its effectiveness without predefined clustering centers or numbers, yielding results comparable to measured data and RocScience dips, thereby satisfying accuracy requirements and exhibiting robust performance.

The transverse displacement significantly affects the coupling efficiency of fiber head. This paper introduces a directional tapered fiber connector designed to enhance coupling efficiency. Compared with the traditional connector, the new connector expands the receiving area of the incident light to improves the receiving performance. Next, the total reflection characteristics and power coupling characteristics of tapered fiber are analyzed theoretically. The theoretical analysis results show that the new tapered fiber head can effectively improve the coupling efficiency. To validate the performance of the new connector, a sample was fabricated and subjected to bit error rate experiments under micro-vibration conditions. The experimental results confirm that the tapered connector exhibits a lower bit error rate and superior performance in micro-vibration environments.

This study utilized transient autofluorescence spectroscopy to measure the autofluorescence lifetimes of normal and cancerous colorectal tissues at five optimal excitation-emission wavelengths. The performance of these lifetimes for classifying normal and cancerous tissues was evaluated. The results indicate significant differences in autofluorescence lifetimes between normal and cancerous colorectal tissues at wavelengths of 340~380 nm, 340~470 nm, 405~515 nm, and 405~635 nm. Jouden index analysis determined classification thresholds of 6.153 ns, 5.847 ns, 5.130 ns, and 6.414 ns, respectively. The receiver operating characteristic (ROC) curve analysis indicated that the peak diagnostic performance was achieved at 405~635 nm, with sensitivity, specificity, and area under the curve (AUC) values of 85.7%, 100%, and 0.908 (P<0.001, 95% CI: 0.78~1.00), respectively. The findings suggest that autofluorescence lifetime measurements serve as a promising diagnostic biomarker for colorectal cancer, potentially aiding in its early detection.