摘要：
As living standards rise, people have higher requirements for the quality of duck eggs. The quality of duck eggs is related to their origin. Thus, the origin traceability and identification of duck eggs are crucial for protecting the rights and interests of consumers and preserving food safety. As the world's largest producer and consumer of duck eggs, China's duck egg market suffers from a severe lack of duck egg traceability and rapid origin identification technology. As a result, a large number of duck eggs from other regions are sold as products from well-known brands, which seriously undermines the rights and interests of consumers and is not conducive to the sound development of the duck egg industry. To address the above issues, this study collected visible/near-infrared spectral data online from duck eggs of three distinct origins. To reduce noise in the spectral data, various pre-processing algorithms, including MSC, SNV, and SG, were employed to process the spectral data of duck eggs in the range of 400-1100 nm. Meanwhile, CARS and SPA were used to select feature variables that reflect the origin of duck eggs. Finally, classification models of duck egg origin were developed based on RF, SVM, and CNN, achieving the highest accuracy of 97.47%, 98.73%, and 100.00%, respectively. To promote the technology's implementation in the duck egg industry, an online sorting device was built for duck eggs, which mainly consists of a mechanical drive device, spectral software, and a control system. The online detection performance of the machine was validated using 90 duck eggs, and the final detection accuracy of the RF, SVM, and CNN models was 90%, 91.11%, and 94.44%, with a detection speed of 0.1 s, 0.3 s, and 0.5 s, respectively. These results indicate that visible/near-infrared spectroscopy can be exploited to realize rapid online detection of the origin of duck eggs, and the methodologies used in this study can be immediately implemented in production practice.
关键词：
Sc modification;DED;microstructure;mechanical property;heat-affected zone
摘要：
Aluminum alloy is an important material used in railway train structures. It is of great significance to repair aluminum alloy through directional energy deposition to reduce cost and improve the performance of the aluminum alloy. In this study, 7N01 aluminum alloy was repaired by means of laser-directed energy deposition (DED) with the powder of Sc-modified Al-Zn-Mg aluminum alloy as raw material. The microstructure and mechanical properties of the repaired specimens were studied through the metallographic microscope, scanning electron microscope, electron backscatter diffraction, universal tensile test, and Vickers hardness test in combination. The results show that the bonding interface of the repaired aluminum alloy is satisfactory, and the porosity is 2.8%. The grains in the repaired area are the columnar crystals growing vertically along the boundary of the melt pool with an obvious temperature gradient. Fine equiaxed crystals are distributed along the boundary of the melt pool, and Al-3(Sc,Zr) particles play a role in grain refinement. The average grain size of the fine grain area in the repair zone next to the fusion zone is 9.1 mu m, and the average grain size of the coarse grain area is 20 mu m. The average tensile strength in the area of repair approaches 349 MPa, which is 91% that of the base material, and the elongation rate is 10.9%, which is 53.2% that of the base material. The hardness ranges between 122 HV and 131 HV, which is comparable to the base material. However, there is a significant decrease in the tensile strength and hardness of the base material (heat-affected zone).
通讯机构：
[Yang, L ] W;Wuhan Polytech Univ, Coll Mech Engn, Wuhan 430048, Hubei, Peoples R China.
关键词：
Brown rice kernel;Bio-structure;Starch granules;Fracture mechanics
摘要：
The microscopic and macroscopic structure of brown rice kernel determines that it is a complex bio-material. Therefore, revealing kernel structural characteristics and fracture mechanisms can provide a reference for related processing application situations. In this study, an in-situ observation method with the multi-layer structure optical platform was developed to better understand the kernel fracture behavior. SEM images show that the starch structure distribution inside the endosperm layer could be divided into core, transition and outer layers. Meanwhile, kernel interior crack formation mechanism was revealed under quasi-static compression and verified from the perspective of fracture and structural mechanics. Typical kernel contact surface expansion behavior under compression conditions was analyzed. The results indicate that the compressive strength of glutinous kernel (56.3 MPa) larger than indica (48.1 MPa), and it was affected by kernel surface dimension and microscopic structure. The study aims to in-depth analysis fracture mechanism of brown rice kernel during the processing, providing a methodological reference for bio-material fracture.
通讯机构：
[Pei, HC ] W;[Xing, L ] N;Wuhan Polytech Univ, Sch Mech Engn, Wuhan 430048, Peoples R China.;Northumbria Univ, Mech & Construct Engn, Newcastle Upon Tyne NE1 8ST, England.
关键词：
Air-cooled PEMFC stack;air supply mode;temperature distribution;multizone temperature measurement;blowing air supply mode;suction air supply mode
摘要：
Open-cathode air-cooled proton exchange membrane fuel cell stack relies on air fans both for fuel supply and stack cooling. Inappropriate stack thermal management and non-uniform temperature distribution can lead to compromised stack performance, reduced lifespan, and even thermal runaway. Thus, temperature distribution measurement, investigation and analysis are essential for air-cooled PEMFC's optimized operation and performance. This study uses a multi-zone temperature measurement approach to investigate the impact of air supply method, airflow, and output current on stack temperature distributions. The experimental results reveal that the highest stack temperature occurs at the cathode channel outlet, while the lowest temperature is near the hydrogen inlet. At a 75A load, the maximum temperature difference between the inlet and outlet is 17 degrees C. Increasing fan speed from 4500 to 8800 r/min reduces temperature non-uniformity in cell 10, the most uneven among the 19 cells, by 11.2%. Comparing blowing and suction air supply modes, blowing enhances stack output performance by 2.1%, with smaller temperature differences. Specifically, cell 10 experiences a 7.5 degrees C lower difference at 4500 r/min and a 3.6 degrees C lower difference at 8800 r/min airflow. Under blowing air supply, temperature non-uniformity decreases by 36.95% at 4500 r/min and 29.2% at 8800 r/min.
摘要：
Purpose This paper is concerned with the H-infinity optimization design of passive and active dynamic vibration absorbers (DVAs) attached to an undamped or damped primary system.Methods The proposed optimization method is an efficient non-smooth H-infinity-synthesis algorithm that is utilized to solve structured H-infinity-synthesis in control engineering. This method can conveniently achieve the optimal design for the amplitude magnification factors of both the absolute and the relative displacements of a DVA using the proposed dual H-infinity design, and implement co-design of H-infinity-optimal proportional-integral-differential controllers and passive parameters of an active DVA.Results Two active DVAs and two variant passive DVAs reported in the literature are taken as examples for design improvement. The optimization results indicate that the proposed method has significant advantages over the conventional fixed points-theory-based methods and many numerical global optimization methods.Conclusions The proposed H-infinity optimization design yields much better vibration suppression result for proportional-integral differential control based active DVAs and variant passive DVAs with complicated structures. It is directly based on their equations of motion in state-space forms, and explicit formulations of various amplitude magnification factors, such as those on the absolute and the relative displacements and active force, need not be derived in the MATLAB environment. A possible situation of occurrence of large amplitude of the relative displacement in DVAs rarely considered in the literature can be handled by using the proposed dual H-infinity design.
摘要：
Mo, TiH(2), Al and graphite elemental powders were used as starting materials for the activation reaction sintering process, which was employed to fabricate porous Mo(2)TiAlC(2). The alteration of phase constitution, volume expansion, porosity, pore size and surface morphology of porous Mo(2)TiAlC(2) with sintering temperatures ranging from 700 °C to 1500 °C were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and pore size tester. Both the pore formation mechanism and activation reaction process at each temperature stage were investigated. The experimental results illustrate that the sintered discs of porous Mo(2)TiAlC(2) exhibit obvious volume expansion and pore structure change during the sintering process. Before 1300 °C, the volume expansion rate and porosity increase with the increment of temperature. However, with the sintering temperature above 1300 °C, the volume expansion rate and porosity decrease. At the final sintering temperature of 1500 °C, porous Mo(2)TiAlC(2) with a volume expansion rate of 35.74%, overall porosity of 47.1%, and uniform pore structure was synthesized. The pore-forming mechanism of porous Mo(2)TiAlC(2) is discussed, and the evolution of pressed pores, the removal of molding agents, the decomposition of TiH(2), and the Kirkendall effect caused by different diffusion rates of elements in the diffusion reaction are all accountable for the formation of pores.
期刊：
Energy Conversion and Management: X,2023年20:100478 ISSN：2590-1745
通讯作者：
Houchang Pei<&wdkj&>Lu Xing
作者机构：
[Zhangda Liu; Liangbo Sun; Wenli Zhu; Yana Li; Houchang Pei] School of Mechanical Engineering, Wuhan Polytechnic University, Wuhan 430048, China;[Lu Xing] Mechanical and Construction Engineering, Northumbria University, Newcastle upon Tyne NE1 8ST, U.K
通讯机构：
[Houchang Pei] S;[Lu Xing] M;School of Mechanical Engineering, Wuhan Polytechnic University, Wuhan 430048, China<&wdkj&>Mechanical and Construction Engineering, Northumbria University, Newcastle upon Tyne NE1 8ST, U.K
关键词：
dead-end PEMFC;Current density distribution;Gas pressure;Reverse current
摘要：
Uneven current density distribution in a proton exchange membrane fuel cell (PEMFC) can decrease the reactant and catalyst utilization, reduce the energy conversion efficiency of the whole fuel cell, and even lead to a shortened cell life. Therefore, studying current density distribution has a critical role in the research and development of PEMFC. To investigate the distribution of the proton exchange membrane fuel cells' local current density under different operating conditions, a single cell using the segmented cell technique consisting of 36 zones was designed. The results show that the maximum current density first appears at the outlet and then moves to the inlet. In addition, when the cell output is stable, the most negligible current density appears in the cell's middle area. The current density distribution was improved when the cell temperature was 50 °C. Compared with other operation temperatures (without cooling, 40 °C, 60 °C), the current density is decreased by 14.0 %, 9.8 %, and 40.6 %, respectively. At the same time, the cell voltage is increased by 10 %, 6.45 % and 22.22 %, respectively. Higher gas pressure is more favourable to improving cell performance and the uniformity of current density distribution. However, when the cathode gas pressure exceeds that of the anode, the reverse inverse current is pronounced in the middle of the cell at the starting process. The reverse duration of the 50 °C cell is reduced by 30 s (25.4 %) compared to the cell without cooling.
关键词：
stability;polarization vortex;phase field simulations
摘要：
Mastering the variations in the stability of a polarization vortex is fundamental for the development of ferroelectric devices based on polarization vortex domain structures. Some phase field simulations were conducted on PbTiO3 nanofilms with an initial polarization vortex under uniaxial tension or compression to investigate the conditions of vortex instability and the effects of aspect ratio of nanofilms and temperature on them. The instability of a polarization vortex is strongly dependent on aspect ratio and temperature. The critical compressive stress increases with decreasing aspect ratio under the action of compressive stress. However, the critical tensile stress first decreases and then increases with decreasing aspect ratio, then continues to decrease. There are two inflection points in the curve. In addition, an elevated temperature makes both the critical tensile and compressive stresses decline, and will also cause the aspect ratio corresponding to the inflection point to decrease. These are very important for the design of promising nano-ferroelectric devices based on polarization vortices to improve their performance while maintaining storage density.
摘要：
Dispersions around the Dirac points in sonic crystals give rise to various extraordinary transport proper-ties of sound waves. In particular, with tilted Dirac cones, the acoustic Dirac crystals will exhibit obvious anisotropic properties. When the Dirac cone is titled to a certain degree, a unique type-III Dirac point emerges with the extreme anisotropic-wave-transport property, which features the crossing of flat bands and linear dispersions. Recently, some quantum and artificial structures have been proposed to realize dif-ferent types of Dirac points, where the type-III Dirac point in sonic crystals has rarely been studied so far. Here, we utilize the orbital modes in an acoustic honeycomb lattice to obtain strictly flat bands through eliminating & pi; bonding. The type-III Dirac points emerge with modulated intercell and intracell couplings, which are simulated with specific structural parameters. At type-III Dirac points, the acoustic wave propa-gation is extremely anisotropic and manifests as plaquette states that exist in the two-dimensional flat-band systems. Inspired by the unique properties at the type-III Dirac points, hybrid acoustic Dirac lattices of regions characterized by different wave-propagation directions are used to conduct the montage operation of plaquette states. The orbital type-III Dirac cones and the montage operation of plaquette states provide opportunities for manipulating energy flow in exotic ways and expanding the potential applications of Dirac materials.
摘要：
The insulated-gate bipolar transistor (IGBT) represents a crucial component within the domain of power semiconductor devices, which finds ubiquitous employment across a range of critical domains, including new energy vehicles, smart grid systems, rail transit, aerospace, etc. The main characteristics of its operating environment are high voltage, large current, and high power density, which can easily cause issues, such as thermal stress, thermal fatigue, and mechanical stress. Therefore, the reliability of IGBT module packaging has become a critical research topic. This study focuses on the damage of power device solder layers and applies heat transfer theory. Three typical solders for welding IGBTs (92.5Pb5Sn2.5Ag, Sn3.0Ag0.5Cu (SAC305), and nano-silver solder paste) are analyzed using JMatPro software to simulate their characteristics. First, a finite element analysis method is used to simulate the entire IGBT module with ANSYS Workbench platform. The study compares the impact of three types of solders on the overall heat transfer of the IGBT module under normal operation and welding layer damage conditions. The characteristics are analyzed based on changes in the junction temperature, heat flow path, and the law of thermal stress and deformation. The findings indicated that under steady-state working conditions, adjacent chips in a multi-chip IGBT module had significant thermal coupling, with a maximum temperature difference between chip junctions reaching up to 13 °C, and a phenomenon of heat concentration emerged. The three types of solders could change the thermal conductivity and heat transfer direction of the IGBT module to varying degrees, resulting in a temperature change of 3-6 °C. Under conditions of solder layer damage, the junction temperature increased linearly with the severity of the damage. In the 92.5Pb5Sn2.5Ag and Sn3.0Ag0.5Cu (SAC305) solders, the presence of intermetallic compounds (IMCs) led to more stress concentration points in the solder layer, with the maximum stress reaching 7.14661 × 10(7) MPa and concentrated at the edge of the solder layer. The nano-silver solder layer had the best thermal conductivity, and the maximum thermal deformation under the same conditions was only 1.9092 × 10(-5) m.
摘要：
PurposeThis paper aims to identify the optimal forming angle for the selective laser melting (SLM) process and evaluate the mechanical properties of the SLM-formed GH3536 alloy in the aero-engine field.Design/methodology/approachForming the samples with optimized parameters and analyzing the microstructure and properties of the block samples in different forming angles with scanning electron microscope, XRD, etc. so as to analyze and reveal the laws and mechanism of the block samples in different forming angles by SLM.FindingsThere are few cracks on the construction surface of SLM formed samples, and the microstructure shows columnar subgrains and cellular subgrains. The segregation of metal elements was not observed in the microstructure. The pattern shows strong texture strength on the (111) crystal plane. In the sample, the tensile strength of 60 degrees sample is the highest, the plasticity of 90 degrees forming sample is the best, the comprehensive property of 45 degrees sample is the best and the fracture mode is plastic fracture. The comprehensive performance of the part is the best under the forming angle of 45 degrees. To ensure the part size, performance and support structure processing, additional dimensions are added to the part structure.Originality/valueIn this paper, how to make samples with different forming angles is described. Combined with the standard of forged GH3536 alloy, the microstructure and properties of the samples are analyzed, and the optimal forming angle is obtained.
通讯机构：
[Bin Li] S;School of Mechanical Engineering, Wuhan Polytechnic University, Wuhan, Hubei 430023, China
摘要：
Deep eutectic solvent (DES) was synthesized from urea (U), acrylamide (AM) and choline chloride (ChCl), sodium alginate (SA) was selected as filler, and SA/P(U-AM-ChCl) composite hydrogel was prepared by thermal initiation frontal polymerization (FP). The hydrogels were characterised by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The effects of SA on the swelling properties, mechanical properties and self-healing properties of the composite hydrogels were investigated. The results show that the swelling properties of the composite hydrogel with the addition of SA are greatly enhanced due to the large number of hydroxyl groups contained in the SA chain. The tensile strength of the hydrogel gradually increased with increasing SA content, with the maximum tensile strength increasing by a factor of 2.89. The self-healing efficiency of the composite hydrogel gradually increased with the increase of SA, and the healing rate of FP5 reached 94.4% after 48 h of healing. This study provides a simple and rapid method for the preparation of composite hydrogels with good mechanical properties and self-healing properties.
通讯机构：
[Li, YN ] ;Wuhan Polytech Univ, Sch Mech Engn, Wuhan 430023, Peoples R China.
关键词：
Bio-based polymer;active and smart packaging;antibacterial;blending ratio
摘要：
Food Science and Technology International, Ahead of Print. <br/>A series of biodegradable colorimetric films were prepared by using chitosan and polyvinyl alcohol as matrix, in which, the weight ratio of chitosan: Polyvinyl alcohol was 100: 0, 80: 20, 50: 50, 20: 80, or 0: 100, with addition of 10% (w/w, relative to chitosan) anthocyanins extracted from purple tomatoes (purple tomatoes anthocyanin) as pigment. The aim of this study was to observe the effect of weight ratio (chitosan: Polyvinyl alcohol) on the mechanical properties, contact angle, swelling rate, pH sensitivity, antioxidant properties of chitosan-polyvinyl alcohol/purple tomatoes anthocyanins films, and the antibacterial activity of films produced for pork packaging. In addition, the films as a smart colorimetric indicator for monitoring the freshness of pork was investigated. The results showed that as the ratio of chitosan to polyvinyl alcohol decreases, the elongation at break, hydrophilicity, and swelling rate of the films increased especially from 16.5% to 174.2% for elongation at break and 93.0° to 53.8° for water contact angle, however, the tensile strength decreased from 67.3 to 24.7 MPa. With decreasing of chitosan: Polyvinyl alcohol, the antibacterial activity on pork was decreased, and the antioxidant properties of films increased first then decreased. Fourier transform infrared spectroscopy indicated there were interactions among chitosan, polyvinyl alcohol, and purple tomatoes anthocyanins. The color response of films was depended on pH, as well as the immersion time. The longer immersion resulted in a more pronounced color change. The color changed from purplish red (pH 2–4) to green (pH 5–10) to yellow (pH 10–12). In monitoring the freshness of pork, the film showed a nice visual color change, indicating a potential application in smart packaging. These bio-based materials may be useful alternatives to synthetic plastics for food applications such as active and smart packaging, thereby improving the environmental friendliness and sustainability of the food supply.
