International Journal of Precision Engineering and Manufacturing最新文献

There is an increasing demand for durable metallic implants, particularly among elderly patients undergoing revision surgeries for degenerative bone diseases. Approximately 70–80% of the implants are made of metal. Despite their robustness, metallic implants exhibit a higher Young’s modulus than bone, leading to a stress-shielding effect. Although porous structures in implants aim to mitigate this issue, their porosity compromises overall strength. The present study focuses on the design of porous gyroid Ti–6Al–4V specimens and their fabrication using laser powder bed fusion. Subsequently, hydroxyapatite (HAp) combined with polyamide binders was synthesized using the sol–gel method from precursors and infiltrated into porous specimens to enhance their bio-mechanical compatibility. The X-ray diffraction analysis confirmed the presence of both Ti–6Al–4V and HAp. The Tafel plots revealed that the corrosion rate of the porous specimen infiltrated with HAp was about 0.394 mm/year, which is very minimal considering the prolonged implant lifespan. Furthermore, the results from the compression testing revealed that the average Young’s modulus and compressive strength of HAp-infiltrated specimens were found to be increased by 70% and 7.5% respectively when compared to the non-infiltrated porous gyroid Ti–6Al–4V samples. These findings confirm that the HAp not only enhances osseointegration and tissue growth but also enhances the compressive strength of the porous Ti–6Al–4V metallic implants.

This paper focuses on solving the problem of the thrust ripple of the permanent magnet linear synchronous motor (PMLSM) to improve the machining accuracy and stability of the precision platform. The air gap magnetic field model of the permanent magnet magnetic field and the armature permanent magnet magnetic field are established using the equivalent magnetization method and the equivalent current method. The mathematical model of the linear motor is then derived using Clark and Park coordinate transformation. Also, the dynamic equation of the linear motor is developed considering the influence of electromagnetic thrust, detent force, and friction force. The error expressions resulting from thrust ripple are provided. To eliminate the thrust ripple and enhance the accuracy of the linear motor, a linear thrust observer is utilized to compensate for the low-frequency thrust ripple. The compensation current for the thrust ripple is then incorporated into the servo system using a new sliding mode controller. Additionally, a double T-Notch filter is designed to eliminate the interference signal caused by occasional resonance at a specific frequency, thereby ensuring the stability of the system output. Finally, experimental validation is conducted to verify the effectiveness of the proposed strategy, and the results demonstrate a significant improvement in thrust fluctuation and tracking accuracy.

Present work investigates the DC and Analog/RF characteristics such as the drain current (({I}_{D})), Transconductance ({(g}_{m})), Transconductance Generation Factor (TGF), Cut-off frequency ({(f}_{T})), Frequency Transconductance Product (FTP), Transit time ((tau ),) and the total resistance of the source region, drain region, and channel resistance ({(R}_{SD+CH})) for Dual Metal (DM) Inversion Mode (IM) and Junctionless (JL) Cylindrical Gate All Around (CGAA) Silicon nanowire (SiNW) MOSFETs with 5 nm gate length using Silvaco ATLAS 3D TCAD. In this work, the Non-Equilibrium Green’s Function approach along with the self-consistent solution of Schrödinger’s equation and Poisson’s equation has been considered. The channel is taken to be lightly doped in the case of IM DM CGAA SiNW type of device. The effect of DM Gate work function engineering for SiNW channel of diameter 3 nm with gate oxide (({SiO}_{2})) the thickness of 0.8 nm on ({I}_{D}),({ g}_{m}), TGF, ({f}_{T}), (tau), FTP and ({R}_{CH}) has been studied. Moreover, a comparative study has been made between IMDM and JLDM CGAA SiNW devices with the above-mentioned parameters. For the JL device, the optimization of doping concentration is performed to get the same (i) I_ON current and (ii) threshold voltage (V_TH) as the IM device. About 3.09 times and 21.89 times reduction in I_OFF is seen for the same I_ON and V_TH optimized devices respectively as compared to IM device. It has been found that DM Gate variation minimizes drain-induced barrier lowering (DIBL) in IM and JL devices. The JL SiNW showed much lower DIBL ~ 16.46 mV/V, a near ideal SS ~ 60 mV/dec, and higher ({I}_{ON}/{I}_{OFF}) current ratio ~ 7.04 × 10⁸ which is much better as compared to those reported in the literature for cylindrical gate all around (CGAA) devices. Also, it is found that the JL SiNW device performs better than IM in terms of SS, DIBL, ({I}_{ON}/{I}_{OFF}), ({g}_{m},) TGF, f_T, (tau), FTP and ({R}_{SD+CH}).

Additive manufacturing of metals is actively being researched due to its potential for mold modification and cost savings. However, producing smooth aluminum parts with directed energy deposition (DED) using welding heat flux presents material restrictions and challenges. While research has focused on developing cold metal transfer (CMT) with minimal heat input, its application can be costly in industry. To address this issue, we checked over a DED process using pulsed variable polarity (VP) gas metal arc welding (GMAW), which, for the first time, reduces costs compared to CMT. Optimal parameters were determined via experimentation, with deposition efficiency (DE) used to evaluate post-processing loss and deposition performance. Tensile tests were conducted to verify the mechanical properties of deposited specimens, and microstructure analysis was performed. In this study, method achieved a stable deposition tendency with an electrode negative ratio of 18% under the welding conditions of an ER4043 Ø1.2 electrode wire, 120 A, 21 V, 80 cm/min, a shield gas flow rate of 20 L/min, and bead-on-plate position. By varying the layer-by-layer velocity throughout the deposition process, a maximum DE of 82.56% was achieved, resulting in lower post-processing loss than CMT with suppressed anisotropy in the material. Tensile test data and microstructure inspections confirmed isotropic behavior. For the first time in the field of study, this research proved that deposition process by VP-GMAW is cost-effective compared to CMT.

The development of super-resolution imaging techniques has revolutionized our ability to study the nano-scale world, where objects are often smaller than the diffraction limit of traditional optical microscopes. Super-resolution superlenses have been proposed to solve this problem by manipulating the light wave in the near field. A superlens is a kind of metamaterial-based lens that can enhance the evanescent waves generated by nano-scale objects, utilizing the surface plasmon phenomenon. The superlens allows for the imaging of nano-scale objects that would otherwise be impossible to resolve using traditional lenses. Previous research has shown that nanostructures can be imaged using superlenses, but the exact shape of the superlens must be known in advance, and an analytical calculation is needed to reconstruct the image. Localized plasmon structured illumination microscopy is an approach to achieve super-resolution by imaging the superlens-enhanced evanescent wave with illumination shifts. This study proposes a new approach utilizing a conditional generative adversarial network to obtain super-resolution images of arbitrary nano-scale patterns. To test the efficacy of this approach, finite-difference time-domain simulation was utilized to obtain superlens imaging results. The data from the simulation were then used for deep learning to develop the model. With the help of deep learning, the inverse calculation of complex sub-diffraction-limited patterns can be achieved. The super-resolution feature of the superlens based on deep learning is investigated. The findings of this study have significant implications for the field of nano-scale imaging, where the ability to resolve arbitrary nano-scale patterns will be crucial for advances in nanotechnology and materials science.

In this paper, we present an investigation of ultrasonic welding performance for 25 mm² copper wire and T2 copper plate across various welding parameters using orthogonal experimentation. The objective of this work was to explore the influence of operational parameters on the resulting welds. A comprehensive study of the mechanical properties and microstructure of the copper wire-to-copper plate joint was carried out using a series of sophisticated instruments. It includes a universal tensile machine, resistance measuring equipment, SEM, EDS and temperature measuring tool. This multifaceted approach enabled a detailed analysis of the joint's integral features and properties. This provides further insight into its performance and durability. Findings indicate that welding pressure has the most significant effect on welded joints. The optimal combination of parameters is achieved with the welding energy set at 6000 J, the welding amplitude at 85% and the welding pressure at 260 kPa. In different sets of welding parameters, joint strength is positively related to welding parameters and increases with increasing welding parameters. Joint resistance decreases with increasing joint tensile load and conductivity can be used to evaluate ultrasonic welding. It has been found that the development of the welded joint is achieved gradually in a direction moving inwards from the welding tool head, exhibiting a methodical forming process. Three distinct failure modes are observed in welded joints such as joint pullout, joint tearing and busbar breakage. The peak temperature during the welding process was recorded at 373 °C which indicates that the ultrasonic welding is a solid state connection.

Electrospinning represents a straightforward and adaptable technique for producing polymer-based nanofibers. However, many studies lack systematic approaches and fail to provide quantitative accuracy in describing electrospinning process parameters. This often leads to contradictory or inconsistent findings, highlighting the need for orthogonal methods to thoroughly investigate the qualitative and quantitative relationships between fiber characteristics and various processing and material parameters. In this study, polystyrene (PS) was employed using the mixture of N,N-dimethyl formamide (DMF) and tetrahydrofuran (THF) as a solvent, with its applied voltage, nozzle-to-collector distance, PS concentration, and flow rate parameters to be explored using an orthogonal array. Utilizing an L9 (3⁴) orthogonal array design, experiments were conducted with varying electrospinning parameters. The results demonstrated that PS concentration had the greatest influence on the uniformity of fiber diameter, 63%. At the same time, too low PS concentration also led to fibers with irregular beads. This research contributes significantly to the production of uniform fibers with high utility in the field of pollution treatment and medical applications.

The maglev technology has been recently used for advanced semiconductor equipment. The stringent accuracy requirement of the semiconductor manufacturing processes has posed new challenges about modeling and control of maglev systems (MLSs). This paper presents a new sliding mode control (SMC) scheme, named as SMCLFF, to tackle the impacts of inherent non-linearities caused by leakage and fringing fluxes (LFF), and external disturbances caused by the gap measurement mismatch (GMM) and non-orthogonal force (NOF) on the control of the MLS. A dynamic separation model (DSM) is designed to model the LFF effects in both the current–flux density (I–B) relationship and the flux density–force (B–F) relationship. The system is linearized by the DSM firstly, and the residual LFF effects and the external disturbances are suppressed by adaptive RBF neural networks (NNs) in SMCLFF respectively. The stability of the closed-loop control system was analyzed. Experiments were performed on a one-dimensional MLS plant. Results show that the DSM can effectively compensate for the LFF effects, and SMCLFF can enable the MLS to obtain high performance in a closed-loop control system.

Understanding the changes in arterial wall viscoelasticity during the progression of vascular disease is crucial. Nonetheless, there has been a lack of comprehensive investigation into the assessment of viscoelastic parameters and their impact on radial wall motion. To address this gap, we analyzed the radius waveform by solving the viscoelastic constitutive equations of the standard linear model (SLM) based on a thin-wall tube assumption. Additionally, a finite element method (FEM) was applied to simulate radial wall motion for thicker walls. The analytic solution showed that a well-balanced SLM model with the time constant (({tau }_{varepsilon })) values smaller than 0.05 s could effectively simulate the dynamic response of radial wall motion in a human carotid artery. FEM result showed that increasing wall thickness led to a decrease in the amplitude of the radius waveform, while its effect on phase lag was marginal. To evaluate the clinical relevance of arterial wall viscoelasticity, the viscoelastic parameters of the SLM were estimated from the pressure and diameter waveforms of each patient using an optimization technique. The 105 patients were categorized according to their cardiovascular disease risk status, and statistical comparisons were made for viscoelastic parameters across the different groups. The results revealed that the high-risk group exhibited significantly higher wall elasticity than the low-risk group (p < 0.03), while the intermediate-risk group demonstrated higher wall viscosity than the low-risk group (p < 0.01). Therefore, arterial wall elasticity holds potential as a significant indicator for distinguishing between low-risk and high-risk groups, whereas viscosity shows promise as a significant indicator for distinguishing between low-risk and intermediate-risk groups.