Spacecraft solar panels, as critical components for power generation, have difficulties in vibration control due to their unique operating environment. This paper presents an analysis for dynamic behavior and energy transfer in simplified solar panel configurations with embedded acoustic black hole (ABH) by the isogeometric analysis. Non-uniform Rational B-spline (NURBS) functions are employed to describe both the geometric and displacement fields of the ABH solar panel, ensuring high accuracy and reliability in the results. Then, the energy functions in both the uniform, ABH and damping regions are derived. The results calculated by the current method are validated through experimental and traditional finite element results to validate the excellent convergence and high accuracy. The effects of boundary conditions, ply angles, and ply layers on vibration behavior, power flow and structural intensity are systematically analyzed. During the experimental process, the trapezoidal and slanted ABH designs are employed to approximate the ideal ABH curve. The energy flow behavior in three distinct ABH structures is also analyzed. Results indicate that these non-ideal ABH designs can effectively replicate the performance of an ideal ABH. This research offers new perspectives and dependable engineering solutions for the vibration control of solar panel applications in spacecraft.

Developing high-efficiency catalysts for the seawater urea oxidation reaction (UOR) is pivotal to advancing hydrogen production via seawater electrolysis. Defect engineering has established itself as a core strategy for regulating catalytic activity. However, conventional defect regulation technologies are predominantly hindered by inherent drawbacks such as high energy consumption, substantial costs, and environmental contamination. Herein, we introduce high-frequency ultrasonic vibration cold-manufacture (HUVCM) as a novel, eco-friendly, and highly efficient defect engineering approach to fabricate high-performance Ni-based catalysts for seawater UOR. Our findings demonstrate that HUVCM induces the formation of high-density dislocation defects on the surface of Ni-based alloys, which subsequently initiate the in situ construction of ultra-fine nanocrystalline structures with an average grain size of similar to 5 nm. The Ni-based alloys modified by HUVCM exhibit remarkably enhanced catalytic activity toward both the hydrogen evolution reaction and UOR. Notably, for UOR, the catalyst shows excellent activity with merely 1.4 V at 100 mA cm-2, placing the catalyst among the state-of-the-art Ni-based seawater UOR electrocatalysts. We further reveal that the superior catalytic performance stems directly from the elevated valence states of constituent elements, which are effectively modulated by the high-density dislocation defects introduced via HUVCM. This work proposes an efficient and facile defect-engineering strategy for electrocatalysts, while establishing a pivotal foundation for the industrial-scale production of hydrogen via seawater electrolysis. (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(UOR)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic).(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic),(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic),(sic)(sic)(sic),(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic).(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(HUVCM)(sic)(sic),(sic)(sic)(sic)(sic)(sic)(sic),(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic),(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic).(sic)(sic)(sic)(sic),(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic),(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)5 nm(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic).(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic),(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic).(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic),(sic)(sic)(sic)(sic)(sic)100 mA cm-2(sic)(sic)(sic)(sic)(sic)(sic)(sic)1.4 V(sic)(sic),(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic).(sic)(sic)(sic)(sic)(sic)(sic)(sic),(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic),(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic).(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic),(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic).

The in situ fabrication of Ti2AlNb alloy components using premixed powders is associated with issues such as uneven compositional distribution and low performance. This study proposed a powder particle size modulation model to ensure that the mass ratio of single Ti, Al and Nb powders closely approximated the theoretical mass ratio of the Ti2AlNb alloy (46:11:43). Laser-directed energy deposition was then successfully employed to fabricate high-performance Ti2AlNb alloys in situ. The results demonstrated that the three particles meeting the theoretical mass ratio of the alloy could be fully melted and mixed, thereby reducing elemental enrichment and depletion. Owing to different thermal cycles, the phase compositions in the top and middle regions of the component comprised B2 and B2 + alpha 2 + O phases, respectively. Non-uniform heat conduction accelerates the cooling rate, ultimately resulting in increased dislocation density. Faster cooling rates increase KAM, promoting low-angle grain boundaries evolving into high-angle boundaries, and the heat released by the negative mixing enthalpy altered the local heat flow direction at the solid/liquid boundary, thereby changing the growth direction of the original grains and ultimately refining the microstructure. The average ultimate tensile strength (UTS) at room temperature was 994.5 +/- 46.29 MPa.

This study explores the relationship between rock fragment size distribution and disc cutter breaking efficiency of a tunnel boring machine (TBM) using discrete element simulations of indentation tests. Fragmentation behavior was analyzed under varying joint dip angles, joint spacings, and confining pressures, and cutter efficiency was evaluated by correlating fragment gradation parameters with specific energy (SE). The results show that cracks preferentially propagate along the weak joint interfaces, demonstrating that joint geometry controls stress redistribution and fracture evolution. With increasing joint dip angle, crack density and crushed zone extent first increase and then decrease. Reduced joint spacing enhances crack interaction and coalescence, resulting in lower energy demand. In contrast, increasing confining pressure suppresses tensile crack development, restricts crack opening displacement, and promotes shear-dominated failure, leading to finer fragments and higher SE. Strong linear correlations (R² > 0.80) between gradation parameters and SE indicate that fragment size distribution quantitatively reflects variations in energy dissipation during cutter and rock interaction.

The increasing demand for ultra-precision components with complex surface geometries has stimulated the development of advanced deterministic polishing technologies. This investigation explores the impact of external vibration on the rheological properties of polishing slurry and the material removal performance during the vibration-assisted force rheological polishing (VFRP) process. The mechanical response of the vibrating workpiece surface under various vibration conditions was numerically analyzed using ANSYS Fluent 14.5. The results demonstrated a strong correlation between the surface pressure imposed on the workpiece and the applied vibration amplitude as well as vibration frequency. Experimental results validate that the introduction of vibration promotes a reversible rheological transition of the slurry from a fluid-predominant state to a solid-resembling structure, which facilitates abrasive particle confinement and subsequently enhances polishing capability. The reliance of stainless-steel sheet polishing performance on vibration parameters was evaluated. With the optimized combination of polishing speed (40 rpm), vibration frequency (80 Hz), and amplitude (0.35 mm), the 30 min polishing process yielded a material removal rate of 68.1 nm/min and reduced the average surface roughness (Sa) from 80 nm to 7.1 nm. The acquired results provide constructive direction for optimizing the VFRP process and promoting its application in high-efficiency, ultra-precision surface polishing.

With the widespread application of porous materials in engineering structures, porous plates with cutouts have attracted considerable attention due to their advantages such as lightweight design and multifunctional integration. Although acoustic black hole (ABH) structures have been demonstrated to possess excellent wave energy concentration and dissipation capabilities, their vibration responses and energy flow characteristics after the introduction of a cutout and porosity distributions remain unclear, necessitating systematic investigation. To this end, this study, based on the isogeometric method and leveraging its advantages in complex geometric modeling, a dynamic model of the acoustic black hole porous plate with a cutout (ABH-PPC) is constructed, and the governing vibration equations are established according to the first-order shear deformation theory. The effects of three types of porosity distributions, namely uniform, symmetric, and asymmetric, on the structural vibration response, time-averaged power flow, kinetic energy, and power flow density vectors are systematically investigated. The proposed method is rigorously validated through finite element simulations and experimental tests. The results show that a smooth circular cutout, a low-porosity coefficient, and a uniform porosity distribution contribute to excellent vibration suppression over a wide frequency range. Among the three porosity types, the uniform distribution combined with a damping layer yields the highest modal loss factor. The presence of the cutout alters the energy transmission path, with part of the energy radiating outward and the remainder continuing to propagate within the plate after boundary reflection. The shear component of the power flow density vector dominates the total vector field, and the application of the damping layer facilitates partial energy dissipation and regulation. This study provides a theoretical basis for the design of acoustic black hole structures with a cutout and porosity distributions, offering significant reference value for achieving broadband and efficient vibration control.

Exploiting high-performance absorption-dominant electromagnetic interference (EMI) shielding composites is ungently desired yet challenging for minimizing the secondary electromagnetic radiation pollution. Herein, lattice-filler dual-gradient Fe3O4/carbon nanotube/polyurethane&MXene (Fe3O4/CNT/PU & MXene; DGFCP&M) composite frames with a positive gradient of functional filler and a negative gradient of lattice size were successfully fabricated by a powerful multiple-nozzle immersion-precipitation 3D printing (ip3DP) technology. The insulative top layer of DGFCP&M frames with larger lattice pores plays a role as an impedance matching layer to mitigate the reflection of electromagnetic wave (EMW). Nevertheless, the highly conductive bottom layer of MXene with non-lattice structure acts as a reflective layer to reflect EMW back to the interior of DGFCP&M frames. Moreover, hierarchical porous structures (lattice macropores and filament micropores) can prolong the transmitting path to enhance the attention of EMW energy. In consequence, excellent SET of 72.7 dB and A of 0.62 are achieved for DGFCP&M-8 composite frame at EMW incident from top surface, both of which are superior to those of homogenous and single-gradient composite frames. Furthermore, visual simulations intuitively verify that the lattice-filler dual-gradient composite frame has an excellent absorption-dominant EMI shielding performance. The construction of lattice-filler dual-gradient architectures based on multiple-nozzle ip3DP provides a valuable insight into the fabrication and adjustment of absorption-dominant EMI shielding composites for the promising application in next-generation flexible and portable electronic devices.

Functionally graded (FG) plates are widely used in engineering problems, and the presence of open holes is inevitable in practical engineering structures; relevant research on vibro-acoustic behavior and sound radiation characteristics is essential. This paper presents a dynamic model for a double FG plate-cavity coupling system with an open hole. The physical properties of the two plates vary continuously in the in-plane direction. To account for the complex open-hole configuration accurately, isogeometric analysis (IGA) integrated with a multi-patch coupling approach is employed. On the basis of the first-order shear deformation theory (FSDT), the governing equations for the double in-plane FG plate-cavity coupling system with an open hole are formulated by combining energy variational principles. The vibro-acoustic characteristics of this coupling system can be obtained by solving the governing equations, and then the sound radiation is computed using the Rayleigh integral formulation. In numerical analysis, the accuracy of the present model is validated through comparisons with the traditional finite element method (FEM). Subsequently, the influences of the open-hole shape, geometric size, and material properties on vibro-acoustic behavior and sound radiation performance are assessed. This research can provide theoretical guidance for optimizing FGMs and designing open-hole configurations in the future.

Matrix shrinkage/swelling caused by gas adsorption is the key factor affecting gas flow and stability in coalbed methane (CBM) reservoir. Wherein, the thermal effect of coal caused by gas adsorption/desorption will also lead to additional instantaneous thermal expansion. However, the dynamic thermal process of methane adsorption in coal, and the law of temperature change caused by adsorption heat in adsorption equilibrium state are still unclear (Kang et al., 2022; Ye et al., 2023). In this work, a dual-site Langmuir model has been used to describe methane adsorption behavior in coal under specific temperature and pressure conditions. Further, the chain rule and Clausius-Clapeyron equation were introduced to evaluate the thermodynamic characteristics of coal adsorption. It was found that the isothermal adsorption enthalpy in coal revealed an adsorption quantity and temperature dependence. Secondly, based on evolutionary law relating to isosteric enthalpy and specific heat capacity, the temperature increment caused by gas adsorption was obtained. Obviously, the instantaneous temperature increment was related to adsorption capacity and isosteric enthalpy. By linking the temperature change caused by adsorption heat with thermal expansion of coal, the thermal expansion caused by adsorption heat in the equilibrium state of methane adsorption is re-evaluated. On this basis, the coal swelling model considering sorption-induced deformation and sorption-induced thermal expansion is re-established. Meanwhile, according to the change process of coal temperature, thermal volatilization characteristics of coal under the equilibrium state of methane adsorption are also analyzed. In addition, the effects of temperature increase caused by adsorption and environment were considered, with respect to which a porosity model concerning coal-gas interaction in a fracture-matrix system was proposed, that included thermal expansion (including sorptioninduced thermal expansion), thermal volatilization (including sorption-induced thermal volatilization), and gas adsorption/desorption mechanisms. The proposed model provides a tool to quantify the coal swelling and infiltration behavior caused by gas adsorption.

In practical engineering applications, structures often encounter complex and diverse excitation conditions, with multiple sources of excitation acting simultaneously. To effectively suppress vibrations in complex structures, coupled nonlinear energy sinks (CNES) have been proposed. However, current research primarily focuses on vibration control in coupled systems under single-source excitation, which limits the application of the CNES in multi-source excitation systems. To explore the vibration suppression effects of the CNES in complex multi-source excitation environments and its potential applications in vibration control of elastic coupled structures, this study establishes an analytical model of an elastic double-beam system (EDBS) with CNES under dual-source excitation. Based on the generalized Hamilton's principle, the vibration control equations of the EDBS were derived and subsequently simplified into solvable ordinary differential equations using the Galerkin truncation method (GTM). After verifying the accuracy and reliability of the GTM calculation results, this paper conducts a comprehensive study on the effect of the CNES and its core parameters on the vibration characteristics of the EDBS. Additionally, the vibration suppression effect of the CNES on the EDBS under dual-source excitation is further verified by establishing an experimental platform. The results of the numerical analysis and experiment confirm that the CNES with reasonable parameters can effectively suppress the vibration of the EDBS under dual-source excitation. It is worth noting that under complex multi-source excitation, the CNES exhibits two working modes: vibration reduction mode and failure mode. The study demonstrates that the CNES has great potential as a beneficial control strategy for mitigating vibrations in practical applications similar to the EDBS.

FeCoCrNi-based high-entropy alloys (HEA) are utilized in offshore equipment, their inadequate balance of wear and corrosion resistance, coupled with the high proportion of precious metal elements (such as cobalt), restricts their applicability in corrosive and friction-wear multitasking environments. Here, a cobalt-free FeCrNiMoSix dual-phase coating was designed and prepared, and the investigation focused on the systematic examination of the coating's phase transition and characteristics in relation to silicon content. The FeCrNiMoSi0.5 coating was determined to have optimum corrosion resistance, a phenomenon attributed to the synergistic effect of the dual phase structures. And, the hardness increased with the addition of Si, but the anti-wear properties displayed a pattern of initially rising and then falling, because variations in the concentrations of the different phases modify the wear mechanism.

Precision glass molding (PGM) is a net-shape technology that enables the high-precision and high-consistency mass production of glass optical elements. To address issues with surface coatings of super-hard material molds represented by tungsten carbide (WC), including abrasion susceptibility, poor high-temperature stability, short mold life, and adhesion, this paper reports the preparation of a pure ionic tetrahedral amorphous carbon (ta-C) coating onto WC mold surface using filtered cathodic vacuum arc (FCVA) technique. The mechanism whereby bias pressure affected ta-C coating structural composition was analyzed. An innovative approach was proposed for preparing multilayer ta-C coatings with different thicknesses through periodical adjustment of substrate bias pressure and deposition time. The impact of coating thickness on coating microstructure, mechanical, tribological, and glass molding properties was highlighted. Results indicate that a 128-nm-thick PGM coating, produced at -100 V bias voltage, is more suitable. The coating demonstrates excellent performance with high hardness (52.89 GPa), high elastic recovery (similar to 90.4 %), high bond strength (similar to 27.8 mN), low wear rate (similar to 0.666 x 10(-9) mm(3)/Nm), and low coefficient of friction (similar to 0.097). It enables mold high-temperature stabilization molding up to 640 degrees C. The ta-C coating has achieved simultaneous improvements in high-temperature molding life, release (anti-adhesion), and filling (low friction) capabilities of wafer-level glass microlens array mold.

KH560-modified electrolytic manganese slag (EMS)-based cementitious material (EP-K) was successfully prepared in this study through aqueous solution polymerization for use in deep grouting to repair leaking landfills. EP-K with 3 vol % KH560 exhibits higher compressive strength (125.14% higher) and lower permeability (61.29% lower) than before modification. The concentration of contaminants leached in deionized water meets safety standards. Fourier transform infrared (FTIR) and scanning electron microscope (SEM) analyses showed that the epoxy groups in KH560 reacted with the -OH groups of sodium polyacrylate to form a C-O-C structure, which enhanced the densification of the cementitious network. Also, the siloxy groups reacted with EMS to form a Si-O-Si linkage, which reduced holes and cracks. The integrated pollution indicator evaluation method was combined with the weight assignment technique to enhance evaluation efficiency and accuracy, advancing research on the performance and environmental impact of cementitious impermeable materials in solid waste landfills.

In this paper, a new type of hybrid laser welding is introduced to weld SUS301 stainless steel. The influence mechanism of synchronous cold air heat sink process on weld pool thermodynamics and weld microstructure during laser welding of SUS301L stainless steel sheet was analyzed by experiment and simulation. Firstly, the dynamic characteristics of the molten pool were analyzed using high-speed camera technology. The results indicate that applying heat sink can significantly reduce the characteristic length of molten pool. When the heat sink flow rate is 200 ml, the length of molten pool increases by 60.6 % as the heat sink distance increases from 5 mm to 20 mm. Furthermore, a simulation model of SHSLW is established. The simulation results illustrate that cold air heat sink will form a rapid cooling zone at the tail of weld pool, which leads to the disappearance of weld comet characteristics, and improves the temperature field at the tail of weld pool, and the refinement mechanism of heat sink on microstructure was described based on the theory of constitutional supercooling (CS). This new understanding provides an opportunity to make better use of heat sink to control grain structure, and in turn to improve the mechanical properties of the welds, which is also verified by the test results of the properties of the welds. EBSD analysis shows that after adding heat sink, the average size of small grains was 8.43 mu m, accounting for 74 % of the entire grain area, the proportion of low angle grain boundaries decreased to 59.1 %. Compared with LW, the longitudinal and transverse Vickers hardness values of weld fusion zone under SHSLW are increased by 4.17 % and 7.70 % respectively, the tensile strength and maximum ductility increased by 12.03 % and 21.37 %, respectively. It can be concluded that the application of heat sink is an effective way to improve the tensile strength and toughness of the welds by laser welding of metals.

Coupling beam systems have appeared widely in various engineering fields, where several additional beams are generally set near coupling beam systems, which may be designed as a vibration control mechanism by introducing some unique connecting relations. This study introduces nonlinear connecting relations to connect an additional beam and a two-layer beam system, where the additional beam equipped with connecting nonlinear stiffness is defined as an internal beam-type CNES. The Lagrange method is chosen to calculate the nonlinear vibrating system's numerical responses, which can correctly calculate the nonlinear vibrating system's numerical responses. Introducing the internal beam-type CNES is beneficial for broadband attenuation of the vibration of the vibrating system's main structures. The internal beam-type CNES's representative working states are divided into linear and nonlinear broadband vibration attenuating states. The appearance of representative nonlinear responses can be judged as a sign of the internal beam-type CNES working in the nonlinear broadband vibration attenuating state. Increasing the nonlinear stiffness of the internal beam-type CNES can motivate representative nonlinear responses of the vibrating system, while increasing its viscous damping can eliminate representative nonlinear responses. A delicate parameter selection of the nonlinear stiffness of the beam-type CNES helps enhance the vibration attenuation of the two-layer beam. Importantly, the internal beam-type CNES reveals the attractive vibration-attenuation potential in controlling the vibration of coupling beam systems. The proposed internal beam-type CNES provides a feasible way to use unimportant additional beams near main beam structures to control their vibration. It is beneficial for effectively utilizing existing engineering structures to carry out the vibration-attenuation design.

Leakages of electrolytic manganese slag (EMS) disposal sites pose a significant threat to soil and groundwater, necessitating effective in situ remediation technologies. This study presents a multi-scale analysis to elucidate the enhanced impermeability mechanism of EMS composite modified by sodium polyacrylate (PAAS). By integrating macroscopic performance testing (compressive strength, permeability, corrosion resistance, and pollutant leaching), molecular dynamics (MD) simulations, and advanced spectroscopic/microscopic techniques (FTIR, XPS, and EDS mapping), we establish a direct link between macroscopic properties and underlying molecular-level interactions. Results demonstrate that an optimal PAAS/EMS mass ratio of 0.2 significantly enhances compressive strength (12.3-fold increase), reaching 2.78 MPa, and reduces the permeability coefficient to 1.318 x 10-8 cm/s, with leachate concentrations meeting relevant water quality standards. This performance improvement stems from a synergistic multi-scale effect: macroscopically, well-dispersed PAAS forms a cross-linked network, filling structural defects within the EMR matrix and encapsulating the CaSO4 & sdot;2 H2O hard phase; at the molecular level, MD simulations reveal that PAAS chains undergo ion exchange (Na+ with Mn2+) and chelation (between-COO-and Mn2+), forming a multi-crosslinked polymer network that densifies the microstructure and effectively impedes contaminant migration. FTIR and XPS analyses corroborate these molecular interactions, confirming that the enhanced impermeability arises from the synergistic effects of polymerization, ion exchange, and chelation. This study provides a new approach for controlling environmental risks associated with EMS, demonstrating the efficacy of multi-scale analysis in optimizing material performance.

The most significant challenges in the laser additive manufacturing of high-nitrogen steel are nitrogen loss and nitrogen pores, which significantly impact the microstructure and mechanical properties of the fabricated parts. In this paper, the regulation mechanisms of nitrogen loss, nitrogen pores, microstructure, and mechanical properties in the laser-directed energy deposition of nickel-free high-nitrogen stainless steel were systematically investigated. The results indicate that nitrogen loss gradually increases, and the porosity of the deposited samples first increases and then decreases with the increase in heat input. These changes are the result of the combined effects of the temperature, lifetime, solidification rate, and Marangoni flow of the melt pool. The microstructure of the deposited samples is primarily composed of austenite and ferrite phases. The deposited samples exhibit the highest mechanical properties at a moderate heat input of 80 J/mm. Furthermore, the contribution of solid-solution strengthening, grain-boundary strengthening, and dislocation strengthening to the strength of the deposited samples is discussed.

In actual applications, multi-plate systems are broadly applied in various engineering fields. In marine engineering, some floating raft systems are simplified as multi-plate systems with linear connecting layers. If nonlinear connecting layers were used to connect multi-plate systems, nonlinear vibration transmission pathways between the sub-plate would be established. It is hoped that introducing the above nonlinear connecting layers could provide an attractive vibration control effect for the multi-plate systems. However, a few studies implement nonlinearities as a connecting layer between plates, which hinders a comprehensive understanding of the vibration behavior of plates coupled by nonlinear connecting layers and limits their engineering application in vibration reduction for multi-plate systems. Comprehensively considering the limitation of existing research and the potential application value of nonlinear connecting layers in multi-plate systems, this research develops a vibration analysis model for a nonlinear two-plate system in which the nonlinear vibration behavior is predicted using numerical methods. The representative nonlinear behaviors of the system are investigated, with a focus on the influence of the key control parameter of the nonlinear connecting layer on the vibration dynamics of the two-plate model. It is demonstrated that the vibration behavior of the nonlinear two-plate system can be accurately analyzed using GTM. The introduction of the nonlinear connecting layer induces various nonlinear phenomena, including complex behaviors, quasi-periodic vibrations, and the monotonic transfer of vibrational energy. The nonlinear connecting layer establishes an efficient energy transfer pathway, where an optimal parameter value of the nonlinear connecting layer aids in reducing the vibration of Plate 1. Additionally, under appropriate parameters for the nonlinear connecting layer, vibrational energy is effectively transferred from Plate 1 to Plate 2. Notably, to maximize the vibration reduction effectiveness of the two-plate system and leverage the complex behaviors, the nonlinear connecting layer should operate at low values of viscous damping.

The distribution characteristics and magnitude of energy density on the cross section of a laser beam are determined by its spatial profile,which directly impacts heat transport during laser materi-al processing.Hence,it is essential to understand the influence of spatial profiles on heat transport dur-ing laser directed energy deposition with synchronous material delivery.Herein,a three-dimensional heat transport model that takes into account important physical events such as laser-powder-pool coupling,thermal-fluid coupling,solid-liquid phase change,and multiple heat transfer was established.The model was validated using single-track single-layer deposition experiments.The effects of four spatial laser beam profiles,including Gaussian(GP),super-Gaussian(SGP1 and SGP2),and pure flat-topped(FTP)profiles,on the heat transport and fluid flow within the molten pool were investigated.Simulated results show that peak temperatures of the molten pool decrease sequentially under GP,SGP1,SGP2 and FTP,and the temperature gradients on the solidification interface increase gradually from the top to the bottom of the molten pool.Temperature gradients on the solidification interface positively correlate with the angle between the normal direction of the solidification interface and the laser scanning direction,and negative-ly correlate with the distances from the beam center on the molten pool surface.Under all four spatial la-ser beam profiles,temperature gradients at the same positions on the solidification interface near the rear of the molten pool increase,while those at the bottom of the molten pool decrease.The molten pool ex-hibits an outward annular flow pattern under all four spatial laser beam profiles with fluid flows mainly driv-en by Marangoni shear stress.Heat transfer within the molten pool is dominated by Marangoni convec-tion and heat conduction.Average fluid velocities within the molten pool decrease successively according to the following order:Gaussian,super-Gaussian,and pure flat-topped profiles.

Crop disease detection and crop baking stage judgement require large image data to improve accuracy. However, the existing crop disease image datasets have high asymmetry, and the poor baking environment leads to image acquisition difficulties and colour distortion. Therefore, we explore the potential of the self-attention mechanism on crop image datasets and propose an innovative crop image data-enhancement method for recurrent generative adversarial networks (GANs) fused with the self-attention mechanism to significantly enhance the perception and information capture capabilities of recurrent GANs. By introducing the self-attention mechanism module, the cycle-consistent GAN (CycleGAN) is more adept at capturing the internal correlations and dependencies of image data, thus more effectively capturing the critical information among image data. Furthermore, we propose a new enhanced loss function for crop image data to optimise the model performance and meet specific task requirements. We further investigate crop image data enhancement in different contexts to validate the performance and stability of the model. The experimental results show that, the peak signal-to-noise ratio of the SM-CycleGAN for tobacco images and tea leaf disease images are improved by 2.13% and 3.55%, and the structural similarity index measure is improved by 1.16% and 2.48% compared to CycleGAN, respectively.