A magnetic field assisted wire electrical discharge machining and electrochemical machining process (MF assisted WEDM-ECM) is proposed to fabricate two-tiered microstructures on the surface of thick nickel-titanium (NiTi) alloys. The objective is to significantly improve processing quality and efficiency, thereby enhancing surface hydrophobic properties for orthopedic implant applications. Firstly, a simulation model for continuous pulse discharge craters is developed by incorporating a Gaussian heat source and heat transfer theory. By coupling the deflection effect of the magnetic field on electrons with electrode dynamics, a model was established for the time-varying electric field and current in the electrolytic processing region under the influence of a magnetic field. Subsequently, this model was combined with a continuous pulse discharge model to establish a simulation model for the formation process of two-tiered microstructures under MF assisted WEDM-ECM. Secondly, a contact angle prediction model is developed to analyze surface hydrophobicity, combining Wenzel and Cassie-Baxter’s theories. The simulation results indicate that surface roughness decreases and contact angle increases with wider pulse widths and higher peak currents, resulting in enhanced hydrophobicity. Finally, a Taguchi orthogonal experimental design is employed in MF assisted WEDM-ECM. The results demonstrate significant improvements: a 41.97

Shape memory alloys (SMAs) exhibit exceptional functional properties, but their service performance depends strongly on surface integrity and the stability of martensitic transformation. Traditional low-speed wire electrical discharge machining (WEDM-LS) inherently produces a thick recast layer (RL), high residual tensile stress, and surface microstructural damage, thereby degrading functional performance and service reliability. To overcome these limitations, an ultrasonic vibration and magnetic field assisted hybrid wire electrical discharge and electrochemical machining process (USV-MF assisted hybrid WEDM-ECM) was proposed to improve the surface integrity and functional performance of SMAs. To quantitatively predict microstructural evolution across multiple length scales, a cross-scale framework was established by integrating finite element, crystal plasticity finite element, and multilevel cellular automaton (FE-CPFE-MCA) models. Systematic analyses were performed in conjunction with a multi-gradient closed-loop characterization of material characteristics under different processing conditions, spanning macroscopic surface morphology, microstructural evolution, and dislocation behavior. On this basis, novel phenomenological behavior induced by multi-physics was identified, and the evolution pathways of microstructure and functional performance during treatment were elucidated in terms of the underlying mechanisms. The results indicated that performance enhancement was primarily attributed to RL thinning, improved reversibility of martensitic transformation, and the formation of gradient structures. The high reliability of the cross-scale predictions was further validated by in situ EBSD. This study provides a theoretical foundation for the high-quality fabrication and performance control of thin-walled, micrometer-scale precision components manufactured from SMAs and other phase transformation-sensitive metals, with particular applicability to precision medical implants.

Ultraviolet light-assisted chemical mechanical polishing (UV-CMP) is an ultra-precision machining process that combines ultraviolet light-activated chemical polishing fluid with mechanical action. A molecular dynamics model of abrasive particles polishing the monocrystalline silicon surface was established to study the mechanism of material removal at the microscopic level. Simulation data revealed that the material removal rate of abrasive particles scratching the monocrystalline silicon surface with an oxide layer was 17.6

Monocrystalline silicon is widely used in chip and photovoltaic manufacturing. However, processing monocrystalline silicon is difficult due to its high hardness and brittleness. An innovational technology of immersion fluid free abrasive assisted wire sawing (IFAWS) is proposed in this paper, which has the potential to reduce the sawing force on the wire saw and improve the surface quality of workpieces. Firstly, the mechanism of the hydrodynamic pressure effect generated in the process of IFAWS of monocrystalline silicon and its impact on the processing quality are investigated. Secondly, the surface topography of monocrystalline silicon wafers is simulated using MATLAB and validated through experimentation. Finally, to study the sawing force during IFAWS of monocrystalline silicon under different process parameters and the surface quality of the processed workpiece, the experiment about IFAWS is conducted. The experimental results show that the macroscopic sawing force on the diamond wire saw decreases with the axial speed of the saw wire and the diameter of the free abrasive and increases with the feed speed of wire saw; the surface quality of the processed workpiece increases with the axial speed of the saw wire and the diameter of the free abrasive, and decreases with the feed speed of wire saw.

Aiming at the insufficient understanding of the corrosion mechanism in magnetic field assisted electrical discharge machining (MF-EDM), the influence mechanism of magnetic field on discharge corrosion is explored based on the electron drift rule in the composite field. By simplifying the movement of the plasma arc to align with the offset distance of the electron position, and by equating changes in thermal dynamics—such as arc pressure and recoil vapor pressure at the melting metal interface—to the deflection angle of electron velocity direction, a thermo-hydraulic coupling simulation model was ultimately developed. This model was then used to simulate the discharge erosion process in both air and flowing water media. Finally, a magnetic field assisted monopulse discharge experiment was conducted. The results indicate that the magnetic field can enlarge the diameter of discharge crater, slightly reduce the crater depth, and cause the molten metal to burst and boil earlier, thereby accelerating the corrosion rate. The shapes and sizes of the craters obtained from both simulation and experiment exhibit good consistency, with a diameter error of approximately 2

The widespread application of monocrystalline silicon in microelectronics and photovoltaics requires a precise understanding of its complex elastic-plastic deformation behavior, but establishing a high-precision anisotropic constitutive model remains challenging. This study aims to systematically develop and validate an anisotropic kinematic hardening constitutive model for monocrystalline silicon and achieve precise identification of its parameters. First, nanoindentation tests were conducted on monocrystalline silicon with three main crystal orientations 〈100〉, 〈110〉, and 〈111〉 to obtain load-displacement curve data. Based on this, a finite element nanoindentation simulation model was constructed. A local optimization fitting algorithm was employed to ensure iterative stability and efficiency, and the constitutive relation based on energy method of indentation was used to set efficient initial values. Through iterative updates of the constitutive parameters, precise identification of material parameters was achieved. The underdetermined constitutive parameters for the three crystal orientations were successfully identified, and an accurate constitutive model for monocrystalline silicon was established. Based on this model, finite element simulations were conducted for the diamond wire saw cutting process of monocrystalline silicon. The predicted crack depths for different crystal orientations were highly consistent with experimental results, validating the accuracy of the model. This study established an innovative method for constructing and identifying the constitutive model of monocrystalline silicon, providing a reliable theoretical basis for studying its elastic-plastic deformation behavior and processing simulation.

Traditional low-speed wire electrical discharge machining (WEDM) processing of NiTi shape memory alloys (SMAs) often leads to surface micro-cracks and microstructural damage, accompanied by problems such as thick recast layers (RL). To overcome these defects, an ultrasonic vibration assisted wire electrical discharge machining and electrochemical machining process (USV assisted WEDCM) was proposed. A cross-scale modeling framework based on finite element (FE) and cellular automaton (CA) was established to achieve comprehensive prediction spanning from macroscopic process parameters to microscopic structural evolution. Experimental results showed that compared with traditional WEDM, surface roughness was reduced by 39.4%, surface defects were significantly reduced, material removal rate was increased by 40.1%, and the RL was locally eliminated by the USV assisted WEDCM. Microstructural analysis indicated that grain size was reduced by 32.7% and the volume fraction of dynamic recrystallization (DRX) was increased by 13.9%, with errors of 16.5% and 18.3% relative to model predictions, respectively. Wettability analysis showed that the contact angle of the non-grooved surface was reduced by 19.2%, showing hydrophilicity, while the contact angle of the grooved surface was increased by 9.8%, showing excellent hydrophobicity. This study provides a theoretical basis and technical route for the high-efficiency precision manufacturing of difficult-to-machine materials, which is of great significance for improving surface integrity and strengthening material properties.

The surface quality of wire-saw cut monocrystalline silicon is affected by its anisotropy. This work investigates the effect of anisotropy on the surface quality of monocrystalline silicon (100), (110), and (111) crystalline surfaces in wire-saw cutting processing. The material properties of monocrystalline silicon in different crystal directions are analyzed, and the expressions of elastic modulus of monocrystalline silicon (100), (110), and (111) crystal surfaces are derived, and the influences of material properties and process parameters on macroscopic sawing force and material removal are investigated. The single abrasive grains scratching the surface of monocrystalline silicon and the wire saw cutting and processing process were simulated, and the diamond wire saw cutting and processing of monocrystalline silicon experiment was carried out. The experiment results show that: When the wire saw cuts and processes the (100), (110), and (111) crystal surfaces, the cutting angle with better sawing performance is 30 degrees. The macroscopic normal and tangential average sawing forces on the crystalline surface of monocrystalline silicon (110) differed by 7.22N and 2.54N. The average error between the experiment value of surface warpage and the simulation value is 5.47 %, which indicates the accuracy of the surface morphology prediction model.

In order to establish a shape-properties integrated digital twin framework for magnetic field assisted electrical discharge machining (MF-WEDM), this study developed a multi-scale wettability simulation model based on the lattice Boltzmann method (LBM), which directly correlates micro-morphological parameters of the surface with performance metrics, thereby enabling the direct simulation of virtual surface properties. Secondly, influences of the virtual surface roughness and waviness on the antenna of MF-WEDM were studied for the first time by using the constructed multiphase flow model, which provided a foundational basis for optimizing both process and texture parameters. Then, the textured surface characterized by orthogonal geometric parameters, including topline length, baseline length, waist width, and groove depth, was designed, and its wetting characteristics were simulated. The geometric structure of the texture was optimized based on the simulation results of the contact angle (CA) and the wetting state. Finally, a superhydrophobic surface with hierarchical structure was fabricated using MF-WEDM process in one step, and the simulation results were validated. The research results indicate that the unique rough surface formed by MF-WEDM can enhance the CA of TC4 surface from 79 to 113°, while appropriately designed submillimeter micro-grooves can further increase it to 151.3°, accompanied by a sliding angle (SA) of 8.6° as measured using small droplets (5 µL). The wetting states obtained from both LBM simulations and experiments are in complete agreement, with an average error of only 1.3° and standard deviation of 4.6° for the CA. The developed all-digital model can directly realize the unique surface functions in the cutting and forming process of parts, and has an important reference for the efficient preparation of functional surfaces.

The microstructure evolution and mechanism of the heat-affected layer of nickel-titanium shape memory alloy (NiTi SMA) during low-speed wire electrical discharge machining (WEDM-LS) are investigated by integrating the finite element method and the cellular automata (CA) method. First, an accurate single-pulse discharge heat source model is established to simulate the distribution of temperature, stress and strain fields on the workpiece surface under different electrical parameters. Then, the dynamic recrystallization (DRX) and thermoelastic martensitic transformation of NiTi SMA during machining are simulated using the CA method. Furthermore, WEDM-LS machining experiments and metallographic analysis are conducted to validate the reliability of the simulation results. The findings reveal that DRX of austenite grains in the heat-affected layer contributes to grain refinement on the workpiece surface. The result shows that increasing the peak current from 8A to 12A enhances the DRX fraction from 9.3

In the early stages of designing large aircraft systems, incorporating relevant testability analysis and fault localization into actual project design has become essential. Traditional testing and maintenance methods for unmanned aerial vehicles can no longer ensure the high reliability of operation in large and complex systems. As a result, higher requirements have been established for the system's testability and maintainability. Additionally, the aircraft digital test system, as a critical component of the aircraft ground test and control system, necessitates more stringent design standards in testability design. This paper employs a hybrid approach combining genetic algorithms and discrete particle swarm optimization to identify the minimum set of test items, subject to constraints of fault detection rate and fault isolation rate. To address the issue of optimizing the test sequence, which may be computationally intensive when using graph search algorithms in large systems, discrete particle swarm optimization is integrated to improve the selection process during the expansion of test items. By utilizing genetic algorithms and discrete binary particle swarm optimization for the optimization of test item selection, multiple runs are conducted to obtain the optimal minimal set of test items. Once the minimum set is identified, a well-structured test sequence can significantly enhance the efficiency of fault isolation and the development of fault management strategies within the system.

This study presents an innovative ultrasonic (US) and magnetic field (MF) assisted wire electrical discharge machining-electrochemical machining (WEDM-ECM) complex process, designed to enhance the microstructural and mechanical properties of the surface metamorphic layers (SML). A thermomechanical coupling model was developed to characterize the distribution of temperature, stress and strain fields in the heat affected zone (HAZ) of a nickel-titanium shape memory alloy (NiTi SMA), and a model for the removal of RL under multi-field coupling was also established. Subsequently, a coupled finite element and cellular automaton (FE-CA) model was employed to investigate the microstructural evolution under dynamic thermomechanical coupling, elucidating the critical role of dynamic recrystallization (DRX) in grain refinement. Experimental and characterization analyses further validated the effectiveness of varying electrolyte effect, MF intensity, and ultrasonic amplitude in controlling the microstructural features of the SML. Cross-scale analyses integrating both microstructural and macroscopic properties revealed that the complex machining reduced the SML average grain size by 81.86 %, improved grain uniformity, and achieved a high-angle grain boundary (HAGB) proportion of 73.6 %, with a simulation error of 17.5 %, as compared with the traditional WEDM. Moreover, the process improved surface quality by reducing recast layer (RL) thickness by 51.0 %, enhancing hydrophobicity, and refining microstructure. This process demonstrates substantial potential in improving surface microstructure and mechanical properties, offering theoretical insights and practical guidance for the precision machining of high-performance materials.

Diamond wire sawing is one of the key technologies in semiconductor chip and photovoltaic module manufacturing process. The existence of subsurface damage (SSD) after diamond wire sawing has a great impact on the fracture strength of monocrystalline silicon wafers, which leads to an increase in the waste rate of silicon wafers in subsequent processing. Therefore, it is necessary to evaluate the SSD depth in monocrystalline silicon wafers induced by ultrasonic vibration assisted wire sawing (UAWS). In this paper, the equal probability method is used to establish the wire saw surface morphology model. Then, according to the vibration dynamic equation of the wire saw under transverse ultrasonic, the trajectory equation of any abrasive particle is derived. On this basis, based on the material removal model and indentation fracture mechanics, an analytical prediction model of SSD depth of monocrystalline silicon wafers processed by UAWS was established. Finally, validity of the prediction model is verified by comparing with experimental results. The results show that the average error between the experimental value of the SSD depth and the theoretical value of the prediction model is 9.26

Bionic porous titanium alloy structures have demonstrated broad application prospects in the field of biomedicine, and selective laser melting (SLM) has become one of the main methods for preparing porous titanium alloy structures due to its high degree of forming freedom. Residual stress is a crucial indicator for evaluating the forming quality of SLM parts, thus its control methods have garnered significant attention. Therefore, it is important to understand the process parameters' influence on the generation and regulation of residual stresses in SLM-formed bionic porous titanium alloy parts. In this paper, finite elements and experiments are employed to research the relationship between process parameters and residual stresses in the SLM process, and a method for controlling residual stresses in the key sensitive areas is proposed. It is found that increasing the laser scanning speed is conducive to reducing the residual stress of the porous structure and alleviating the phenomenon of stress concentration. Appropriately increasing the laser power can reduce the residual stress in the Z direction of the porous structure, with the optimal range being from 200W to 250W. Using a medium laying powder thickness (0.03mm~0.04mm) results in uniformly distributed residual stress on the surface of the porous structure, leading to the attainment of maximum residual compressive stress. Building upon this foundation, the experimental verification of forming quality established stability, while the derived parameter optimization method and forming mechanism offered theoretical support for process optimization in fabricating porous titanium alloy structures through SLM.

In this paper, a novel ultrasonic cavitation (USC)-assisted low-speed WEDM (WEDM-LS) process is proposed to address the issue of low machining efficiency and the recast layer when cutting thick nickel-titanium shape memory alloy (NiTi SMA) workpiece. Based on the Rayleigh-Plesset model, the machining mechanism of USC-assisted WEDM-LS is explored. Firstly, considering the influence of WEDM on vapor volume fraction (VVF) in the flow field, the impact strength of microjet, which is caused by collapsing near-wall acoustic bubbles on the workpiece surface, is studied. In addition, the influence of a single bubble collapse microjet impacting on the workpiece surface and recast layer is simulated and analyzed based on water hammer effect. The results demonstrated that the microjet is useful for removing workpiece material. The verification experiment results showed that, compared to traditional WEDM-LS, the material removal rate (MRR) of USC-assisted WEDM-LS increases by 31.65

Diamond wire sawing plays an important role in semiconductor processing. Considering that the cavitation effect can improve the machining quality, a new technology of ultrasonic cavitation–assisted diamond wire sawing (UCAWS) is proposed in this paper. To study the formation process of cavitation in UCAWS and its influence on processing, a simulation and experimental study of cavitation in UCAWS is conducted. The pressure distribution model and cavitation model of two-phase mixed flow around wire sawing in UCAWS are constructed by combining the ideal bubble dynamic theory. The effect of vapor volume fraction (VVF) on cavitation intensity is calculated using computational fluid dynamics (CFD). The simulation results show that transient cavitation and steady-state cavitation exist simultaneously around wire sawing and with the increase of ultrasonic amplitude, the cavitation effect is enhanced. UCAWS experiments are conducted on monocrystalline silicon to study the changes in sawing force and workpiece surface roughness. The experimental results show that the sawing force of the UCAWS decreases by 6.65

The indirect Evaporative Cooler (IEC) utilizes exhaust air from air-conditioned spaces to precondition outdoor air, offering a low-carbon and efficient solution for cooling the air and expanding its application scope. This study developed a mathematical model of IEC, considering the effects of primary air condensation and channel wettability. The correlations of eight parameters on evaluation indexes were analyzed to rank their influence for IEC, revealing that outdoor climate, indoor air conditions, geometric shape, and channel wettability are the main factors affecting cooling efficiency and energy recovery capacity. Subsequently, a comparison of the temperature and humidity distribution inside the IEC under high and low wettability showed that under high-wettability, the cooling effect of the IEC for primary air increased by 23.7 %, and the dehumidification capacity improved by 52.9 %. The performance study of the IEC across seven geographical regions in China indicates that cities with a wet-bulb efficiency greater than 45 % are predominantly located in Northwest China and North China. East China, Central China, and South China exhibit significantly higher average condensation coefficients and cooling capacities compared to other areas, with values of 2.36, 2.26, and 2.56 for the condensation coefficients, and 14.2 kW, 14.7 kW, and 14.9 kW for the cooling capacities, respectively.

In the field of one-step efficient preparation of dewetting droplet arrays, the process is hampered by the requirement for low chemical wettability of solid surfaces, which restricts the complete transition of wetting state and its broad prospects in biological applications. Inspired by the physical structure of the lotus leaf, enabling it to promote the change of the infiltration state of an aqueous solution on the surface, we developed a method of one-step fabrication of droplet arrays on the biomimetic structural chip designed in the present work. This greatly reduces the need for chemical modification techniques to achieve low wettability and reduces the reliance on complex and sophisticated surface preparation techniques, thus improving the fabrication efficiency of droplet arrays fully generated on a chip by one-step operation without the need for extra liquid phase or the control of harsh barometric pressure. We also studied the influence of dimensions of the biomimetic structure and the preparation process parameters such as number of smears and speed of smearing on the preparation rate and uniformity of the droplet arrays. The amplification of templating DNA molecules in the droplet arrays prepared in a one-step fabrication way is also performed to verify its application potential for DNA molecular diagnosis.

Diamond wire sawing is one of the key technologies in solar cell manufacturing process and semiconductor chip manufacturing process. The thinned of silicon wafer has become a development trend of semiconductor industry, and the reduction of silicon wafer thickness can improve the material utilization and reduce the manufacturing cost. Therefore, the minimum thickness analytical model of diamond wire saw cutting monocrystalline silicon wafer is proposed in this paper to study the processing mechanism of minimum thickness of monocrystalline silicon wafer. Firstly, based on the Kirchhoff's thin plate theory, the theoretical equation of the maximum internal stress of single silicon wafer and the sawing thickness of the silicon wafer is derived from the sawing force model. Combined with the Mohr's strength theory, the analytical model of minimum sawing thickness of monocrystalline silicon wafer is established. Then, the analytical model is verified by the finite element simulation. The average error between the simulation results and the calculation results of the analytical model about the minimum sawing thickness of silicon wafer is 9%. Finally, the monocrystalline silicon sawing verification experiments are conducted under some groups of processing conditions. The experimental results show that the minimum sawing thickness of the silicon wafer decreases with the increasing axial speed of the wire saw, increases with the increase of the feed rate of the wire saw, and decreases first and then increases with workpiece speed becoming large. The average error of the experimental results and the calculation results of the analytical model of the wafer minimum sawing thickness is 7.4%, which verifies corrections of the analytical model.

Biosafety issues have aroused global concern, especially after the severe acute respiratory syn-drome coronavirus 2 (SARS-CoV-2) Omicron strain of corona virus disease 2019 (COVID-19) caused incalculable human and property losses. Laboratory-acquired infections (LAIs) caused by improper operations or accidents are frequently reported. Research is urgently needed for a mobile biosafety level-4 (BSL-4) laboratory with a high risk for exposure. Deposition character-istics and the spatial distribution of bioaerosols under two typical cases were studied in this paper. Based on the age of air and simulation of airflow pattern, a detailed analysis of infection risk and the distribution of bioaerosols was conducted. The deposition characteristics of particles on different surfaces were analyzed based on particle tracking technology. The results showed that the removal rate of bioaerosols was lower in the space area of the laboratory from 1.6 m above the ground. The distribution of high-risk areas is affected by the coupling of equipment layout and pollution sources, mainly located downstream of the main airflow in the laboratory, and the particle concentration was eight times that of the low-risk areas. More than half of bioaerosol particles are deposited on laboratory equipment and walls. The number of particles deposited on the wall was the largest, accounting for 25.02% of the total. The unit area deposition ratio of the experimental table was the highest, which was 6.14 %/m2. The main deposition area of each surface was determined, which could be of guiding significance to the determination of the key disinfection location of the mobile BSL-4 laboratory.