Search Results (124)

The dissimilar joining of aluminum alloy and carbon fiber-reinforced polymer (CFRP) is critical for lightweight manufacturing in transportation and aerospace sectors, yet it remains challenging due to their substantial differences in physical and chemical properties. This paper systematically reviews friction stir welding (FSW) of aluminum alloy and CFRP, and compares it with laser welding, induction welding, resistance welding, and ultrasonic welding. The comparative analysis indicates that while each alternative process presents distinct limitations in thermal management, heating uniformity, or joint configuration, FSW demonstrates the most balanced overall performance, uniquely combining single-pass long-distance capability, low heat input, and broad industrial applicability. Through systematic parametric analysis, the optimal FSW processing window is quantitatively established as a tool rotation speed of 1200–1500 rpm combined with a traverse speed of 30–50 mm/min. Under these optimized conditions, the CFRP side remains below its thermal degradation threshold of 350 °C, the defect volume fraction is reduced from 12% to below 3%, and the maximum joint tensile strength reaches 78 MPa, representing 65% of the base CFRP strength. The interfacial bonding mechanisms are identified as mechanical interlocking and localized chemical bonding, which however cover only approximately 30% of the interfacial area. Optimization strategies, including surface modification, auxiliary structures, nanoparticle reinforcement, and external field assistance, are evaluated for their effectiveness in improving joint quality. Finally, critical challenges and future research directions toward engineering application are outlined. Full article

Wire Arc Additive Manufacturing (WAAM) is a cost-effective and scalable technique for producing large metallic components; however, coarse columnar microstructures, strong crystallographic texture, and significant residual stresses limit its widespread adoption. Hybrid WAAM processes that integrate deformation-based techniques have been developed to address these limitations. This review provides an analysis of deformation-assisted WAAM, covering interlayer rolling, friction stir processing (FSP), machine hammer peening, laser shock peening, and ultrasonic-vibration-assisted techniques. These hybrid techniques introduce additional thermomechanical parameters (strain, strain rate, and applied stress) that significantly influence microstructure evolution. The governing physical metallurgy mechanisms are discussed in detail, including dislocation accumulation, recovery, static and dynamic recrystallization, and severe plastic deformation. Studies from 2022 to 2025 are critically reviewed, highlighting the effectiveness of hybrid WAAM in promoting columnar-to-equiaxed grain transformation, reducing anisotropy, mitigating defects, and improving mechanical properties across aluminum, titanium, steels, and nickel-based alloys. The integration of auxiliary processes such as in situ machining and heat treatment is also discussed. This review establishes a process–structure–property framework for hybrid WAAM and provides guidance for the development of advanced additive manufacturing systems for the production of near-net-shape components, with reported yield-strength gains of 20–40%, elongation gains of 10–30%, and fatigue-life improvements of up to 60% relative to as-built WAAM. Full article

The expansion of paper-based and wearable microwave electronics demands conductors that are highly conductive, finely patterned, mechanically robust, and compatible with low-cost, biodegradable substrates. This study reports a laser-scribing strategy for high-performance copper–liquid metal (Cu–LM) conductors on paper based on laser sintering of Cu–LM composite particles, with an auxiliary adhesive transfer step to facilitate integration on flexible substrates. Laser-induced reactive sintering creates a network wherein sintered liquid metal and CuGa₂ acts as a conductive bridge, interconnecting the dispersed Cu particles. This provides efficient electron transport pathways, achieving a high conductivity of 4.2 × 10⁶ S/m under optimal laser conditions, surpassing that of pure eutectic gallium–indium (EGaIn) alloys. The self-healing nature of LM enables exceptional mechanical flexibility and stable electrical performance under severe deformation. The utility of this platform is demonstrated by a miniaturized microwave liquid level sensor that provides multi-parameter water-level detection and sensor calibration. These results establish laser-scribed Cu–LM on paper as a low-cost and disposable option for high-performance microwave sensors and flexible wireless electronics. Full article

Terrestrial Laser Scanning (TLS) can provide detailed three-dimensional structural information for individual trees and has become an important data source for tree species classification. However, most existing models are trained using leaf-on point clouds and therefore tend to rely heavily on leaf distribution and crown appearance. When the input changes from leaf-on point clouds to woody-dominated representations, classification performance often declines. To address this issue, this study proposes a mixed-input tree species classification framework for six typical temperate broadleaf tree species. First, a KPConv-based wood–leaf separation model was used to extract woody point sets from leaf-on TLS point clouds, thereby generating woody-only representations for subsequent classification. Second, a multi-task learning network based on DGCNN was constructed. In addition to the main task of tree species classification, an auxiliary task for input-representation discrimination was introduced to enhance the model’s adaptability to different input forms. Experiments were conducted using a dataset composed of local TLS samples from China and publicly available single-tree point clouds from the BioDiv dataset. The results show that the proposed method achieved an overall accuracy of 94.3% on the mixed test set of six typical broadleaf tree species, with average Precision, Recall, and F1 values of 94.3%, 93.6%, and 93.9%, respectively. These results indicate that integrating woody structural representations with multi-task learning can effectively alleviate overreliance on leaf-on appearance features and improve classification robustness under different input representations. Full article

Jet machining is widely utilized in innovative technology industries, such as aerospace and semiconductors, due to its minimal thermal damage. However, with the increasingly stringent surface quality requirements of modern manufacturing, conventional jet technologies face limitations in achieving ultra-precision surface finishing and high material removal rates. To address these challenges and adapt to this new situation, multi-energy field-assisted jet machining has emerged as a novel concept, integrating laser, ultrasonic, and magnetic fields. This paper reviews the scientific development and recent advancements of these hybrid technologies within the field of ultra-precision machining. The physical interaction mechanisms between the auxiliary energy fields and the waterjet are elucidated. Specifically, the effects of laser thermal softening, ultrasonic cavitation, and magnetic focusing on new mechanisms of material removal and surface topography are systematically analyzed. The process capabilities and applications of each method are evaluated. Finally, current technical challenges are identified, and the future trends in ultra-precision jet machining are discussed. Full article

Laser SLAM is a key enabling technology for autonomous navigation of intelligent mobile robots. The standard FLOAM algorithm experiences low positioning accuracy, weak anti-interference performance, and prone error accumulation in pure LiDAR scenarios, making it difficult to meet practical engineering requirements. The focus of numerous studies is thus on improved pure laser SLAM algorithms that are highly robust. The enhanced algorithm of FLOAM GICP registration and SOR filtering is applied in this study. The SOR filtering processes the laser point cloud to remove outlier noise. The GICP registration replaces the classic with an optimized matching cost function. Experiments are conducted on a mobile robot with a Leishen C16 LiDAR to simulate real-life tests in an indoor corridor and outdoor plaza on the Gazebo simulation platform. The results from the EVO tool’s quantitative evaluation indicate that the indoor mean absolute error and RMSE were reduced by 46.67% and 41.67% compared with FLOAM. The outdoor mean and maximum errors are reduced by 46.00% and 70.00%, respectively. The proposed improved scheme achieves centimeter-level positioning accuracy and strong robustness in pure laser configurations without auxiliary sensors such as IMUs or odometers, providing a reliable technical solution for the engineering application of mobile robots in sensor-constrained scenarios. Full article

During laser processing, optimizing the cutting performance by adjusting the angle or off-axis displacement between the auxiliary gas flow and the laser beam is an effective approach to improving processing quality and efficiency. However, traditional electromechanical actuators suffer from inherent limitations in compactness and multi-degree-of-freedom cooperative control, which restrict their applicability in high-speed and high-precision laser cutting systems. To address these limitations, this paper presents a five-degree-of-freedom magnetic levitation actuator for laser cutting lens control and proposes a multi-degree-of-freedom cooperative control strategy based on backstepping control (BC) to cope with the system’s strong coupling, nonlinearity, and model uncertainty. First, a dynamic model of the actuator system is established, and a corresponding BC is designed. Subsequently, a centralized control framework is developed, and comparative simulations and experiments are carried out between the proposed BC and a conventional PID controller. The experimental results demonstrate that the proposed BC method outperforms the PID controller in terms of multi-degree-of-freedom cooperative control capability and dynamic response, thereby significantly enhancing the overall control performance of the system. Full article

We propose a compact, beaconless inter-satellite laser communication tracking system based on direct fiber control to address the complexity and resource demands of conventional pointing, acquisition, and tracking (PAT) architectures. Unlike traditional sensor-based or beacon-assisted schemes, the proposed method employs a piezoelectric ceramic tube (PCT) to generate high-frequency, small-amplitude nutation of the single-mode fiber (SMF) tip, enabling real-time alignment correction using only the coupled optical power of the communication signal. This fully closed-loop tracking approach operates without position sensors and eliminates the need for beam splitting, external beacon sources, or auxiliary position detectors. A theoretical model is developed to analyze the influence of algorithm parameters and optical spot jitter on dynamic tracking performance. Experimental results show that the closed-loop system reliably converges to the optical spot center, achieving a fine-tracking accuracy of 4.6 $\mathsf{\mu }$rad and a disturbance suppression bandwidth of 200 Hz. By significantly simplifying the terminal architecture, the proposed approach provides an efficient and SWaP-optimized solution for inter-satellite and satellite-to-ground optical communication links. Full article

Gas–liquid discharge shows great promise for enhancing the efficiency of diverse energy conversion systems; however, its inherent stochasticity and instability hinder precise process control. Here, we use femtosecond laser-induced discharge combined with space–time resolution spectroscopy to achieve stable and tunable plasma generation at the gas–liquid interface. Experimental results show that the interface reduces the breakdown electric-field threshold by about 25%, shortens the breakdown delay by about 80 ns, and markedly suppresses timing jitter compared with air and the formation of high-density, low-temperature plasma, indicating that liquid-derived species participate in and reshape the ionization pathways. This work provides a controllable platform for the study of gas–liquid discharge and new insights for the design of efficient plasma auxiliary systems for multiphase flow energy conversion. Full article

Laser welding of 6061 aluminum alloy often results in coarse microstructures and inferior corrosion resistance due to rapid solidification. This study introduces ultrasonic vibration as an auxiliary technique to address these limitations. The paper systematically investigates the influence of laser weld ultrasonic assistance on the microstructure and corrosion behavior of a 6061-T6 aluminum alloy welded joint. The results demonstrate that ultrasonic assistance refined the grain structure and reduced the corrosion current density by 19.1% compared to conventional laser welding, achieving 73.6% of the base metal’s corrosion resistance. The enhancement is attributed to ultrasonic-induced acoustic streaming and cavitation, which promote equiaxed grain formation and impede corrosive penetration. The enhancement is attributed to ultrasonic-induced acoustic streaming and cavitation, which promote equiaxed grain formation and impede corrosive penetration. Under the ultrasonic effect, the number of dimples in the weld fracture increased and the depth was significant, which enhanced the tensile strength of the 6061 Aluminum alloy weld. This work provides a reliable and efficient strategy for producing high-performance aluminum alloy welded structures in industrial applications. Full article

In this study, a novel direct laser beam turning (DLBT) approach is proposed for the precision machining of AISI 308L austenitic stainless steel, which eliminates the need for cutting tools and thereby eradicates tool wear and vibration-induced surface irregularities. A nanosecond-pulsed Nd:YAG fiber laser (λ = 1064 nm, spot size = 0.05 mm) was used, and Ø1.6 mm × 20 mm cylindrical rods were processed under ambient conditions without auxiliary cooling. The experimental framework systematically evaluated the influence of scanning speed, pulse frequency, and the number of laser passes on dimensional accuracy and material removal efficiency. The results indicate that a maximum diameter reduction of 0.271 mm was achieved at a scanning speed of 3200 mm/s and 50 kHz, whereas 0.195 mm was attained at 6400 mm/s and 200 kHz. A robust second-order polynomial correlation (R² = 0.99) was established between diameter reduction and the number of passes, revealing the high predictability of the process. Crucially, when the scanning speed was doubled, the effective fluence was halved, considerably influencing the ablation characteristics. Despite the low fluence, evidence of material evaporation at elevated frequencies due to the incubation effect underscores the complex photothermal dynamics governing the process. This work constitutes the first comprehensive quantification of pass-dependent diameter modulation in DLBT and introduces a transformative, noncontact micromachining strategy for hard-to-machine alloys. The demonstrated precision, repeatability, and thermal control position DLBT as a promising candidate for next-generation manufacturing of high-performance miniaturized components. Full article

Laser cladding, a cutting-edge surface modification technique for metals, offers a novel approach to enhancing the wear and corrosion resistance of substrates due to its rapid heating and cooling capabilities, precise control over coating thickness and dilution rates, and non-contact processing characteristics. However, disparities in the physical properties between the coating material and the substrate, coupled with the improper utilization of process parameters, can lead to coating defects, thereby compromising the quality of the coating. This paper examines the effects of material systems and process parameters on laser cladding composite coatings and shows that cracking is mainly caused by thermal and residual stresses. This article summarizes the methods for crack improvement and prevention in five aspects: the selection of processes in the preparation stage, the application of auxiliary fields in the cladding process, heat treatment technology, the use of auxiliary software, and the search for new processes and new structural materials. Finally, the future development trends of laser cladding technology are presented. Full article

This study investigates the modeling of surface roughness (Ra) in the laser cutting of EN 10130 steel process by integrating classical statistical and machine learning methods. First, a quadratic model was developed using response surface methodology (RSM) based on a Box–Behnken experimental design with 17 runs, using cutting speed, laser power, and auxiliary gas pressure as input parameters. Although the RSM model achieved an R² value of 0.8227, there were still some nonlinear deviations between the predicted and experimental values. To improve the prediction accuracy, a regression tree algorithm was applied to model the residuals of the RSM output. The resulting hybrid model, which combines RSM predictions with machine learning-based corrections, yielded a higher R² of 0.8889 and a lower RMSE compared to the original RSM model. A leave-one-out cross-validation (LOOCV) was performed to evaluate the generalization, which resulted in an RMSE of 0.3241 and an R² of 0.6039. These findings confirm the effectiveness of the hybrid approach in capturing complex dependencies and improving prediction accuracy, highlighting its potential for advanced process modeling in laser machining. Full article

In this study, we have compared different Rydberg atom-based microwave electrometry techniques under the same experimental conditions and using the same Rydberg states ($68S_{1/2}$, $68P_{3/2}$, and $67P_{3/2}$). The comparison was carried out for the following techniques: (i) auxiliary microwave field, (ii) microwave amplitude modulation, and (iii) polarization spectroscopy. Our results indicate that all three techniques have a similar minimum measurable microwave electric field. A slightly better result can be obtained by performing polarization spectroscopy using a Laguerre–Gauss coupling laser beam. Full article

Space-to-ground laser communication (SGLC) offers a paradigm-shifting solution to overcome the bandwidth constraints of radio frequency systems by leveraging laser beams for ultra-high data throughput, although its link availability probability is significantly affected by atmospheric conditions such as cloud cover. Existing ground station (GS) placement methods decouple site selection from downlink scheduling, failing to effectively quantify the data throughput of candidate sites. This study proposes a data throughput-driven joint optimization framework that integrates downlink scheduling into the site selection model for the first time. Additionally, the site selection model also incorporates equipment cost constraints and service capacity limitations by introducing an integer variable Q to characterize the deployment scale of laser communication terminals (LCTs) at each GS. Through auxiliary variable linearization techniques, the site selection problem is transformed into a tractable integer linear programming (ILP) formulation. A branch-and-bound algorithm is proposed to achieve global optimal solution search. Numerical results demonstrate that the proposed approach improves data throughput compared to the existing method. Full article