摘要：
The welding process and the properties of welding instruments may improve the mechanical performance of an item. One of these properties is the length of the welding tool. This approach has a substantial effect on the mechanical strength of the metallic matrix. The current study used molecular dynamics modeling and LAMMPS software to evaluate the effect of welding tool length on the mechanical properties of a welded Cu-Ag metallic matrix. This simulation makes use of the Lennard-Jones potential function and the embedded atom model. First, the equilibrium phase of modeled samples was verified by changing the computation of kinetic and total energies. Next, the mechanical properties of the welded matrix were studied using the stated Young's modulus and ultimate strength. The stress-strain curve of samples demonstrated that the mechanical strength of atomic samples increased as the length of the welding tool (penetration depth) increased. Numerically, by increasing the tool penetration depth of Fe tools from 2Å to 8Å, Young's modulus and ultimate strength of the matrixes sample increase from 34.360GPa to 1390.84MPa to 38.44GPa and 1510MPa, respectively. This suggested that the length of the Fe welding tool significantly affected the mechanical properties of the welded metallic matrix. The longer the length of Fe welding tools, the more particles were involved, and consequently, more bonds were formed among the particles. Bonding among the particles caused changes in mechanical properties, such as greater ultimate strength. This method can optimize mechanical structures and be useful in various industries.
通讯机构：
[Wu, Y ] W;Wuhan Polytech Univ, Coll Mech Engn, Wuhan 430048, Peoples R China.
关键词：
AZ31 magnesium alloy;Stamping forming;GA;DBO algorithm;BP neural network;RF regression model
摘要：
To study the formability of AZ31 magnesium alloy under different temperature conditions and improve the forming quality of its parts, this paper aims to solve the minimization problem of pursuing the "maximum thinning rate". This study obtained the mechanical properties of AZ31 magnesium alloy at 25 degrees C, 150 degrees C, 250 degrees C, and 350 degrees C through uniaxial tensile tests and explored the stamping formability of AZ31 magnesium alloy mobile phone cases using the finite element inverse calculation method (MSTEP). Based on the hot stamping of AZ31 magnesium alloy at 250 degrees C, the Monte Carlo Simulation (MCS) method was used to randomly sample the blank holder force, stamping speed, friction coefficient, and resistance coefficient, and then simulate to obtain the corresponding "maximum thinning rate". In addition, a hybrid prediction model optimized by Genetic Algorithm (GA) and Dung Beetle Optimization (DBO) based on the Back Propagation Neural Network (BPNN) - Random Forest (RF) was used to explore the nonlinear relationship between blank holder force, stamping speed, friction coefficient, resistance coefficient, and the "maximum thinning rate". The results show that the plasticity of AZ31 magnesium alloy enhances with the temperature increase, especially exhibiting the best stamping formability at 250 degrees C. Feature importance indicates that the resistance coefficient and stamping speed have a greater impact on the maximum thinning rate, while the influence of blank holder force and friction coefficient is relatively smaller. Mean Square Error (MSE) shows that the predictive capability of the hybrid model is significantly superior to that of the single BP neural network and Random Forest model, displaying optimal efficiency. The predicted maximum thinning rate by the model is 15.39 %, with an error rate of only 0.32 % compared to the DYNAFORM finite element software simulation results, confirming the correctness, accuracy, and effectiveness of the prediction model. Overall, this study provides practical optimization strategies for metal stamping forming processes, with significant practical application value.
摘要：
Rechargeable flexible zinc-air batteries (FZABs) are promising alternatives to lithium-ion batteries for portable and wearable devices. A critical component of FZABs is the gel polymer electrolyte (GPE), which faces challenges such as water loss and poor tensile flexibility under extreme conditions. These issues must be addressed to ensure high utilization of the Zn anode and air catalyst and to meet the demands of harsh environments. This study presents a dual-network GPE leveraging the physical crosslinking between polyacrylic acid (PAA) and kappa-carrageenan (KC) for FZABs. The polar -COO- groups in PAA and the hydroxyl and glycosidic groups in KC form strong hydrogen bonds with H2O molecules, achieving high water retention and strong adhesion to the electrode surface. Additionally, the dual-network structure and ionic bonds between the -OSO3- groups in KC and Na+ cations dissipate energy during stretching, enhancing tensile flexibility. Compared to PAA GPE, the PAA-KC GPE showed remarkable improvements, with maximum elongation increasing by 745 % to 710 %. The water retention rate of PAA-KC GPE exceeded 60 % after 107 h of air exposure. The cycle life of PAA-KC GPE-based FZABs (63 h at 2 mA cm(-2)) was 1.86 times longer than that of PAA GPE-based FZABs. Even under extreme temperatures (-20 degrees C similar to 80 degrees C), PAA-KC GPE-based FZABs demonstrated excellent stability. The developed PAA-KC dual-network GPE shows great potential for flexible energy storage under extreme deformation and temperature conditions.
摘要：
In this research, we present the pure open multi -processing (OpenMP), pure message passing interface (MPI), and hybrid MPI/OpenMP parallel solvers within the dynamic explicit central difference algorithm for the coining process to address the challenge of capturing fine relief features of approximately 50 microns. Achieving such precision demands the utilization of at least 7 million tetrahedron elements, surpassing the capabilities of traditional serial programs previously developed. To mitigate data races when calculating internal forces, intermediate arrays are introduced within the OpenMP directive. This helps ensure proper synchronization and avoid conflicts during parallel execution. Additionally, in the MPI implementation, the coins are partitioned into the desired number of regions. This division allows for efficient distribution of computational tasks across multiple processes. Numerical simulation examples are conducted to compare the three solvers with serial programs, evaluating correctness, acceleration ratio, and parallel efficiency. The results reveal a relative error of approximately 0.3% in forming force among the parallel and serial solvers, while the predicted insufficient material zones align with experimental observations. Additionally, speedup ratio and parallel efficiency are assessed for the coining process simulation. The pure MPI parallel solver achieves a maximum acceleration of 9.5 on a single computer (utilizing 12 cores) and the hybrid solver exhibits a speedup ratio of 136 in a cluster (using 6 compute nodes and 12 cores per compute node), showing the strong scalability of the hybrid MPI/OpenMP programming model. This approach effectively meets the simulation requirements for commemorative coins with intricate relief patterns.
关键词：
Beam shaping;Femtosecond lasers;Lithium niobate;Nonlinear frequency conversion;Nonlinear photonic crystals;Ultrafast lasers
摘要：
<jats:p>We experimentally extend the nonlinear Gaussian to flat-top beam shaping from one to two dimensions through a three-dimensional nonlinear photonic crystal. Employing a near-infrared femtosecond laser, we induce a modification inside lithium niobate to achieve a second-order nonlinear optical coefficient modulation in three dimensions. The flat-topped truncation of wavefront has been adjusted in a mutual perpendicular coordinate separately. Among the generated flat-topped beams, the optimal flatness is 97.1%, and the nonlinear conversion efficiency is 10<jats:sup>−2</jats:sup> at the peak power of 37 kW with the interaction length of 630 µm. By adding an extra dimension, our work simultaneously enables full-wavefront flat-top distribution and nonlinear frequency conversion.</jats:p>
通讯机构：
[Li, JK ] W;Wuhan Polytech Univ, Sch Mech Engn, Wuhan 430023, Peoples R China.
关键词：
Multi-source information fusion;Grain situation analysis;Rice pile characteristics;Space-time law;Evaluation model
摘要：
Grain storage is a complex process, affected by factors such as mold, temperature, humidity, and moisture. The use of multiple sensors to detect changes in rice pile parameters has gained prominence as a means to ensure the accuracy and timeliness of grain condition monitoring. However, the current technology does not effectively utilize data. The assessment criteria primarily rely on grain temperature, and the analysis of grain condition is simplistic. Additionally, it fails to adequately integrate information on temperature, humidity, moisture, gas concentration, and other parameters of the grain pile to form a unified assessment result. To address the isolated and one-sided reaction of various parameters in the grain pile, this thesis conducts research on the storage characteristics of heating, condensation, and mold condition. It combines the information fusion of temperature, humidity, moisture, and CO2 with normal grain conditions, constructs an assessment model based on the classification and identification of grain conditions under gray correlation, and achieves real-time dynamic assessment of the state of the grain pile. The experimental results show that the assessment model based on gray correlation can accurately discriminate between normal and mold conditions, but the accuracy in distinguishing heating and condensation still requires improvement. The overall recognition rate of the four types of grain conditions is 79%, which demonstrates the effectiveness of the model in identifying abnormal grain states.
摘要：
FeCoNiMnCr porous high-entropy alloys were prepared using the activation reaction sintering method with Fe, Co, Ni, Mn, and Cr as raw materials. The oxidation behaviors of FeCoNiMnCrx x porous high-entropy alloys with different Cr contents, such as pore structure, the surface oxide film phase composition, structure, and morphology, were characterized by X-ray diffraction (XRD), electron probe micro analysis (EPMA), energy dispersive X-ray spectroscopy (EDS), and pore tester after high-temperature oxidation at 800-1000 degrees C. The results indicate that the initial porous high-entropy alloy comprises a single FCC solid solution phase. With the increase in Cr content, the average pore diameter, average porosity, and air permeability of the porous high- entropy alloy also increase. The oxidation kinetics of the porous high-entropy alloy after exposure to temperatures between 800 degrees C and 1000 degrees C follows a single-stage parabolic evolution law. At the same oxidation temperature, With the increase of Cr content, the oxidation gains gradually increased, at the same Cr content at different temperatures, the antioxidant performance of 1000 degrees C was the weakest, followed by 800 degrees C, and 900 degrees C showed excellent antioxidant performance. The oxidation products are mainly Mn2O3, 2 O 3 , Mn3O4, 3 O 4 , (Mn, Cr)3O4, 3 O 4 , Cr2O3and 2 O 3 and Fe2O3. 2 O 3 .
通讯机构：
[Li, B ] W;Wuhan Polytech Univ, Sch Mech Engn, Wuhan 430023, Hubei, Peoples R China.
关键词：
Carbon nanotubes;Polymers;Hydrogels
摘要：
In this paper, choline chloride, acrylamide and urea were used to prepare deep eutectic solvent (DES), and CS and N-CNTs were used as fillers to prepare composite hydrogels through in-situ polymerization. Using FTIR and SEM characterization analysis, the results showed that the pressure sensitivity and conductivity of the composite hydrogel were significantly improved after adding CS and N-CNTs. When the filler content reaches the highest level, the pressure sensitivity increases by 13 times and the conductivity reaches 2.05 mS/cm, which is 14.7 times that of the hydrogel without filler. This study provides a preparation method for composite hydrogels with excellent conductive properties and pressure sensitivity.
通讯机构：
[Li, B ] W;Wuhan Polytech Univ, Sch Mech Engn, Wuhan 430023, Hubei, Peoples R China.
关键词：
continuous movement;microwave drying;numerical simulation;rice grains;temperature and moisture
摘要：
This study proposes a simulation strategy that facilitates the continuous movement of rice grains. The study establishes a three‐dimensional model concerning multiple physical fields, including electromagnetism, heat, and mass transfer. It examines the effects of rice grain layer thickness and microwave intensity on the moisture and temperature of rice grains. The drying process is analyzed and studied through mathematical modeling, aiming to improve the efficiency of microwave drying of materials and the quality after drying. Abstract To comprehensively understand temperature and moisture changes in a continuous microwave rice grain drying system, this study proposes a simulation strategy that facilitates the continuous movement of rice grains. The study establishes a three‐dimensional model concerning multiple physical fields, including electromagnetism, heat, and mass transfer. It examines the effects of rice grain layer thickness and microwave intensity on the moisture and temperature of rice grains. The results indicate that the drying rate is negatively correlated with material thickness but positively correlated with temperature. The optimal thickness for the rice grain layer is 8 mm. Furthermore, both the microwave drying rate and temperature increase with microwave intensity. These findings contribute to a deeper understanding of the hydrothermal change mechanisms in rice grains during microwave drying. Practical applications Microwave drying, as an emergent drying technology, has garnered widespread attention for its selective heating, efficient drying, energy savings, and environmental protection. Nevertheless, enhancing uniformity during the microwave heating process constitutes an important research topic in scientific research and technological applications. Numerical simulation methods can visually analyze electric field distribution, thereby optimizing microwave heating uniformity and improving drying effects. This article aims to accurately predict the continuous microwave drying time of paddy and maximize energy usage by optimizing drying thickness and microwave power parameters establishing a mathematical model for the process. The study not only provides a solid theoretical basis for microwave dryer design but also scientifically guides the continuous microwave drying of rice and other food crops.
作者机构：
[He, Dongping; Zhou, Li; Lei, Fenfen; Zheng, Meiyu; Zheng, Jingcheng; Zhang, Tianyu; Nie, Qiangsheng; Zhang, Qinfeng; Hu, Chuanrong] Key Laboratory of Edible Oil Quality and Safety for State Market Regulation, School of Food Science and Engineering, Wuhan Polytechnic University, Wuhan, 430023, China;[He, Dongping; Zhou, Li; Lei, Fenfen; Zheng, Meiyu; Zheng, Jingcheng; Zhang, Tianyu; Nie, Qiangsheng; Hu, Chuanrong] Grain and Oil Resources Comprehensive Exploitation and Engineering Technology Research Center of State Administration of Grain, School of Food Science and Engineering, Wuhan Polytechnic University, Wuhan, 430023, China;[He, Dongping; Wang, Shu] Wuhan Institute for Food and Cosmetic Control, Wuhan, 430012, China;[Hu, Zhigang; Li, Bin] School of Mechanical Engineering, Wuhan Polytechnic University, Wuhan, 430023, China;[Lei, Fenfen] Wuhan Institute for Food and Cosmetic Control, Wuhan, 430012, China. Electronic address: fenfenlei@whpu.edu.cn
摘要：
Dry fractionation represents a significant technique for separation of diverse fractions from beef tallow. The objective of this study was to undertake a systematic investigation of alterations in physicochemical properties, crystallization behavior, thermal properties, and flavor compounds that occur during the beef tallow dry fractionation process. The solid component yielded at 40, 30, and 15°C were 44.88%, 33.72%, and 13.04% respectively, with an 8.36% liquid content at 15°C, which was consistent with the characteristics of saturated fatty acids content. The β - β' transformation in the dry fractionation process was clearly revealed by X-ray diffraction. Differential scanning calorimetry curves exhibited alterations in exothermic and endothermic peak, as well as enthalpy. Electronic nose identified short-chain compounds, aldehydes, ketones, and nitrogen-containing substances as flavor compounds. Volatile compounds were quantified using HS-SPME-GC-MS. Overall, dry fractionation produces beef tallow fractionated compounds with diverse physicochemical properties and aromatic-active substances, thereby expanding its potential utilization.
