期刊：
JOURNAL OF PHYSICS-CONDENSED MATTER,2023年35(20):205701 ISSN：0953-8984
通讯作者：
Shih-Chia Chiu<&wdkj&>Shao-yong Huo<&wdkj&>Chun-ming Fu
作者机构：
[Li, Hong-kang; Yao, Long-chao; Huo, Shao-yong; Fu, Chun-ming] Univ South China, Coll Mech Engn, Hengyang 421001, Peoples R China.;[Hsieh, Kuan-Hong; Chiu, Shih-Chia] 1MORE INC, Shenzhen 518000, Peoples R China.
通讯机构：
[Shih-Chia Chiu] 1;[Shao-yong Huo; Chun-ming Fu] C;College of Mechanical Engineering, University of South China, Hengyang 421001, People's Republic of China<&wdkj&>1MORE INC, Shenzhen 518000, People's Republic of China
关键词：
elastic wave;frequency selective routing;phononic crystals;valley edge states
摘要：
The control of propagation direction or path of edge states is difficult when the chirality of the excitation source and the boundary structures are determined. Here, we studied a frequency-selective routing for elastic wave based on two types of topological phononic crystals (PnCs) with different symmetries. By constructing multiple types of interfaces between different PnCs structures with distinct valley topological phases, the valley edge states of elastic wave could be realized at different frequencies in the band gap. Meanwhile, based on the simulation of topological transport, it is found that the routing path of elastic waves valley edge states highly depends on the operating frequency and the inputting port of the excitation source. By varying the excitation frequency, the transport path can be switched. The results provide a paradigm for the control of elastic wave propagation paths that could be employed for designing the frequency-dependent ultrasonic division devices.
作者机构：
[Lu, Zhendong; Luo, Xiao-Qing; Liu, Qin-Ke; Luo, XQ; Zhou, Yaojie; Wang, Xin-Lin] Univ South China, Sch Elect Engn, Hengyang 421001, Peoples R China.;[Li, Yan] Univ South China, Sch Nucl Sci & Technol, Hengyang 421001, Peoples R China.;[Liu, W. M.] Chinese Acad Sci, Inst Phys, Beijing Natl Lab Condensed Matter Phys, Beijing 100190, Peoples R China.;[Wang, Xin-Lin] Univ South China, Sch Mech Engn, Hunan Prov Key Lab Ultrafast Micro Nano Technol &, Hengyang 421001, Peoples R China.
通讯机构：
[Luo, XQ ] U;Univ South China, Sch Elect Engn, Hengyang 421001, Peoples R China.
摘要：
Chiral metasurfaces, with appealing properties for studying light-matter interactions at the nanoscale, have emerged as a promising platform for the realization of chiral optical responses, thereby showing advantages in chirality-related applications. The conventional approaches primarily concentrate on circular dichroism and the high Q factor of the chiral resonances, while little attention has been paid to the aspects of flexibility and controllability in the modulation of optical chirality, further inhibiting the implementation of tunable and multifunctional chiral metadevices. Here, we employ a planar chiral silicon metasurface governed by bound states in the continuum (BICs) to unravel steerable chiral optical responses. In particular, the BIC-based intrinsic and extrinsic planar chiralities can be precisely steered by breaking the in-plane symmetry and the illumination symmetry, respectively. Moreover, a hybrid Si−VO2 metasurface, manifested by the chiral coupled-mode theory, showcases the feasibility of actively tuning the dissipative loss while maintaining chiral quasi-BICs, then yielding desired loss-steered optical chirality. Our results provide alternative insights into tunable optical chirality and pave the way for advancements in chiroptical applications.
摘要：
Crack formation is a common problem in ceramic additive manufacturing (CAM) process. In this paper, the forming characteristics of indirect ceramic additive manufacturing (DCAM) and direct ceramic additive manufacturing (IDCAM) technologies are comprehensively compared. The morphology and spatial distribution characteristics of micro and macro cracks in CAM are summarized. The crack formation mechanisms in different process stages of IDCAM, such as forming, sintering and cooling are analyzed and in DCAM are mainly discussed from the perspectives of stress distribution and energy release. The crack inhibition methods, including process parameters, auxiliary energy fields and material components are summarized comprehensively. The challenges and possible future trends of crack research in CAM are proposed.
摘要：
Fe50Mn30Co10Cr10 high entropy alloy (HEA) can be considered as a candidate structural and functional material, but the early failure during friction with heavy load can limit its more extensive applications. In this paper, a series of tungsten carbide particle reinforced Fe50Mn30Co10Cr10 HEAs were fabricated by laser cladding tech-nique, the influence of tungsten carbide content on microstructure, mechanical properties and tribological be-haviors were explored systematically. The results indicated that the dissolution and diffusion of tungsten carbide could contribute to a wettability between tungsten carbide and HEA matrix, and grain refinement was caused by increasing tungsten carbide. The UTS and EL of the P10 sample are increased by simultaneously by 26.8% and 31.1% compared with UTS of 696 MPa and EL of 15.1% for P5 sample. UTS and EL were enhanced simulta-neously owing to fine-grained strengthening and nanoscale precipitate strengthening. But higher content of tungsten carbide could cause lower elongation owing to the embrittlement of the materials. Just as this, Rockwell hardness and friction coefficient has an increasing trend with increasing tungsten carbide when an opposite trend exists in volume wear rate. It can indicate that hardness is a more important factor for wear resistance, and excellent wear resistance with 1.25 x 10-5 mm3/(N & sdot;m) appear in higher-content WCp reinforced HEA com-posite. Furthermore, wear mechanism is transformed from abrasive wear in low-content tungsten carbide to adhesive wear in high-content tungsten carbide.
摘要：
This study developed a set of custom made laser remanufacturing equipment for deep penetration laser cladding and remelting tailored to the particular demands of the TC4 alloy. The yield strength improved to 865 MPa after laser cladding and the strength should be a good approximation to substrate. The yield strength was increased to 878 MPa by deep penetration laser remelting in a modified atmosphere. The experimental results of this method demonstrate the effectiveness of deep penetration laser remelting in remanufacturing and its potential to adapt to a wide range of part defects. This study demonstrated that the mechanical strength of TC4 alloy could be enhanced by deep penetration laser cladding and remelting.
摘要：
During the replanting operation of a seedling tray, the end-effector needs to repeatedly grab the qualified plug seedlings in the supply tray and release them to the target tray for replanting, and in the process of grasping, the end-effector may cause some mechanical damage to the plug seedlings, thus affecting their quality. Therefore, in order to be able to adjust the position of the hand claw grasping point according to the morphological characteristics of the plug seedlings and select the optimal grasping point, this paper proposes research on the optimal grasping angle algorithm for plug seedlings based on machine vision. Firstly, a rotatable three-jaw end-effector is designed, which uses a three-jaw structure for grasping the burrowing seedlings. The three claws are driven with a telescopic cylinder to carry out clamping and relaxing actions. The rotation of the three claws is controlled with the stepper motor to adjust the optimal grasping position. Secondly, based on the pre-processing of an image of the hole tray seedling, the extraction of feature points in the region of interest, and the calculation of localization, the angle between the angular bisector of the cotyledon leaf blade of the hole tray seedling and the horizontal positive direction is solved. In this paper, two methods are designed to calculate the coordinates of feature points: one is the geometric method and the other is the center-of-mass method. Finally, the optimal grasping angle is calculated by analyzing the angle between the angular bisector of the cotyledon leaf blade and the horizontal positive direction of the cavity seedlings. According to the test, the average calculation error of the proposed algorithm is 3.12 degrees, and the average calculation time is 0.512 sec/sheet, which meet the requirements of the replanting operation.
期刊：
INTERNATIONAL JOURNAL OF NUMERICAL METHODS FOR HEAT & FLUID FLOW,2023年33(5):1853-1885 ISSN：0961-5539
作者机构：
[Sun, Jinju; Wang, Xuesong; Song, Peng] Xi An Jiao Tong Univ, Sch Energy & Power Engn, Xian, Peoples R China.;[Benini, Ernesto] Univ Padua, Dept Ind Engn, Padua, Italy.;[He, Youwei] Univ South China, Coll Mech Engn, Hengyang, Peoples R China.
关键词：
Axial flow compressor;Aerodynamic performance and stability;Multiobjective optimization
摘要：
Purpose
This study aims to use computational fluid dynamics (CFD) to understand and quantify the overall blockage within a transonic axial flow compressor (AFC), and to develop an efficient collaborative design optimization method for compressor aerodynamic performance and stability in conjunction with a surrogate-assisted optimization technique.
Design/methodology/approach
A quantification method for the overall blockage is developed to integrate the effect of regional blockages on compressor aerodynamic stability and performance. A well-defined overall blockage factor combined with efficiency drives the optimizer to seek the optimum blade designs with both high efficiency and wide-range stability. An adaptive Kriging-based optimization technique is adopted to efficiently search for Pareto front solutions. Steady and unsteady numerical simulations are used for the performance and flow field analysis of the datum and optimum designs.
Findings
The proposed method not only remarkably improves the compressor efficiency but also significantly enhances the compressor operating stability with fewer CFD calls. These achievements are mainly attributed to the improvement of specific flow behaviors oriented by the objectives, including the attenuation of the shock and weakening of the tip leakage flow/shock interaction intensity.
Originality/value
CFD-based design optimization of AFC is inherently time-consuming, which becomes even trickier when optimizing aerodynamic stability since the stall margin relies on a complete simulation of the performance curve. The proposed method could be a good solution to the collaborative design optimization of aerodynamic performance and stability for transonic AFC.
摘要：
To study the effect of three different types of nozzles (straight conical, Venturi, and streamline) on the decontamination effect of radioactively contaminated metals abrasive jet, the gas-solid two-phase flow in the abrasive jetting process is numerically simulated by the method of CFD-DEM coupling simulation. The coverage and distribution uniformity of abrasive particles, the impact velocity, and the wear of the nozzle itself are focused on, and the rationality and reliability of the simulation experiment method and the evaluation method of the experimental results are proved by the verification experiments. The results show that the Venturi nozzle is more suitable for the decontamination of radioactively contaminated metals because it has the advantages of uniform abrasive distribution, high abrasive impact velocity, and good nozzle wear. The nozzle is mainly subjected to low-angle micro-cutting erosion wear, so when selecting nozzle materials, more emphasis should be placed on high-hardness materials to resist micro-cutting wear. The impact distance has a very obvious impact on the decontamination effect of the abrasive. In the decontamination process, the impact distance should be set reasonably, and the uniformity of the abrasive particle distribution should be fully considered to ensure the decontamination effect.
作者机构：
[Yang, Xudong; Zhao, Yingchao; Wang, Jun; Feng, Jun] Univ South China, Coll Mech Engn, Hengyang 421001, Peoples R China.;[Shi, Zhiyong; Zhao, MC; Zhao, Mingchun] Cent South Univ, Sch Mat Sci & Engn, Changsha 410083, Peoples R China.;[Zhao, Yingchao] Hunan Lifang Rolling Roll Co Ltd, Hunan Adv Mfg Engn Technol Res Ctr High Wear Resis, Hengyang 421600, Peoples R China.
通讯机构：
[Zhao, MC ] C;[Zhao, YC ] U;Univ South China, Coll Mech Engn, Hengyang 421001, Peoples R China.;Cent South Univ, Sch Mat Sci & Engn, Changsha 410083, Peoples R China.;Hunan Lifang Rolling Roll Co Ltd, Hunan Adv Mfg Engn Technol Res Ctr High Wear Resis, Hengyang 421600, Peoples R China.
摘要：
Surface coating has been widely used to ameliorate the surface properties of Ti alloys. In this study, high-power pulsed magnetically controlled sputtering technology was used to successfully prepare a nano-CrN/TiN multi-layered coating on the surface of a TC4 Ti alloy. The surface of the obtained coating was uniform, dense, and free of obvious defects. With the decrease in modulation period, the optimal growth of the nano-CrN/TiN multi-layered coating was changed from a (220) crystal surface to (111) and a (200) crystal surface. Compared to the single-layered CrN or TiN coating, the nano-multi-layered coating had higher hardness and lower wear rate. Furthermore, the hardness and the wear resistance increased with the decrease in the modulation period. This presented an optimal modulation period of 6 nm. Meanwhile, the resistance of the obtained coating to high-temperature oxidation at 800 °C was also significantly improved.
通讯机构：
[Hui Lin; Xinlin Wang] A;Authors to whom correspondence should be addressed.<&wdkj&>Hunan Province Key Laboratory for Ultra-Fast Micro/Nano Technology and Advanced Laser Manufacture, School of Mechanical Engineering, University of South China, Hengyang 421001, China<&wdkj&>Authors to whom correspondence should be addressed.<&wdkj&>School of Mechanical and Electrical Engineering, Putian University, Putian 351100, China
摘要：
In order to solve the problem of low accuracy of tool wear detection due to the poor quality of generated data under small sample problems, a deep learning model based on data enhancement and feature fusion is proposed. Firstly, in order to solve the problem that there is no quality evaluation standard in the training process of the traditional generative adversarial network (GAN), the K nearest neighbor algorithm is proposed to test the data generated by the GAN model for the second time. The improved GAN model can be automatically trained to get the optimal model according to the second test results. Secondly, in order to enhance the anti-interference effect of the model, a double-path parallel convolutional neural network (DPCNN) which combines with the characteristics of frequency domain and time-frequency domain is constructed to analyze the wear data. Furthermore, the hyperparameters of the model are optimized by Bayesian optimization algorithm (BOA). Finally, the effectiveness of this method is verified in the saw blade wear detection experiment. The results show that the performance of this model is better than other models, and the accuracy rate in the experimental detection reaches 100%.
作者机构：
[Xiao, Zhang; Sun, Erjie] Univ South China, Coll Mech Engn, Hengyang 421001, Peoples R China.;[Tan, Yu] China Agr Univ, Coll Engn, Beijing 100083, Peoples R China.
通讯机构：
[Zhang Xiao] C;College of Mechanical Engineering, University of South China, Hengyang 421001, China<&wdkj&>Author to whom correspondence should be addressed.
摘要：
In the factory nursery, qualified seedlings can be used to replant unqualified seedlings or missing seedlings in the seedling tray through automatic transplanters. Due to the random positions of unqualified and missing seedlings, the end effector of the automatic replanting machine spends substantial time shuttling between the supply tray and the target tray to complete the replanting task. Therefore, we proposed a fast path planning method based on improved particle swarm optimization and compared it with the fixed sequence method and genetic algorithm in experiments with different replanting numbers in different tray types. The experiment shows that the improved particle swarm optimization algorithm and genetic algorithm can shorten the length of the replantation path by about 20% compared with the fixed sequence method, and the running time of the improved particle swarm optimization algorithm is 57.63% less than the genetic algorithm on average. The replanting path optimization method based on improved particle swarm optimization designed in this research can significantly optimize the length and time of the replanting path of the seedling tray, improve the efficiency of the replanting operation, and meet the real-time requirements.
摘要：
Recently, indoor organic photovoltaics (IOPV) has gradually entered people's field of vision due to the elevated demands of Internet of Things (IoTs). However, the mismatch between the absorption spectrum of organic photovoltaic materials and the emission spectrum of indoor light sources limit the output power of IOPV, which do not meet the requirement of IoTs. In order to clarify this issue, we fabricated three different OPVs by screening three electron acceptors with different absorption spectrum, PC71BM, N2200, and PYF-T, to match with a high-performance wide-bandgap electron-donating polymer containing imide-functionalized benzotriazole units (PTzBI-oF). PYF-T-based device performed best under AM 1.5G sunlight illumination, while PC71BM-based device performed best under indoor LED illumination, which can be attributed to the suppressed dark current (JD) and significantly enhanced parallel resistance (RP) of PC71BM-based device. We systematically analyzed and understood the interrelationship between the absorption spectrum, JD, RP, phase separation morphology, crystalline and orientation behavior, and photovoltaic performance of IOPVs, proving that an extremely low JD and sufficiently large RP is crucial for fabricating efficient IOPVs. The JD suppression can be achieved by morphology regulation of the active layer, where the donor-acceptor pair needs to display a suitable phase separation scale, strong crystallinity, and ideal molecular orientation for the donor-acceptor interface. Our work can provide guidance for the future design of donor-acceptor pairs for efficient IOPV, and promote the further application of IOPV.
期刊：
Journal of Radioanalytical and Nuclear Chemistry,2023年332(9):3733-3740 ISSN：0236-5731
通讯作者：
Liu, L
作者机构：
[Yu, Shiwei; Liu, Lie; Ling, Ke; Liu, L] Univ South China, Sch Elect Engn, Hengyang 421000, Peoples R China.;[Liu, Lie; Zhang, Junze; Han, Lianghua; Liu, L] Univ South China, Sch Mech Engn, Hengyang 421000, Peoples R China.
通讯机构：
[Liu, L ] U;Univ South China, Sch Elect Engn, Hengyang 421000, Peoples R China.;Univ South China, Sch Mech Engn, Hengyang 421000, Peoples R China.
摘要：
A safe and efficient method is necessary for the treatment of high-level liquid waste (HLLW). Therefore, we propose for the first time the use of laser to simulate the glass curing of HLLW. In this paper, borosilicate glasses containing 16% simulated oxides were successfully sintered by laser at different temperatures (1050 & DEG;C-1200 & DEG;C). A series of properties of the obtained cured bodies were analyzed. The results show that the cured body can be prepared above 1100 & DEG;C to meet the requirements. This demonstrates the potential application of lasers in the treatment of HLLW glass curing.
作者机构：
[Liu, Ji; Zhou, Xin-Yue; Hu, Bin; Zhang, Bing; Wu, Yang-Wen; Lu, Qiang; Chen, Hao-Ze] North China Elect Power Univ, Natl Engn Res Ctr New Energy Power Generat, Beijing 102206, Peoples R China.;[Mi, Teng-Ge] Univ South China, Sch Mech Engn, Hengyang 421001, Peoples R China.
通讯机构：
[Ji Liu; Qiang Lu] N;National Engineering Research Center of New Energy Power Generation, North China Electric Power University, Beijing 102206, PR China
关键词：
Cu catalyst;Furfural;Furfuryl alcohol;Hydrogenation;Ni doping
作者机构：
[Cao, Yuanlong; Lyu, Peng] Univ South China, Sch Mech Engn, Hengyang 421001, Peoples R China.;[Cao, Yuanlong; Li, Wenjun; Feng, Kai] Hunan Univ, State Key Lab Adv Design & Mfg Vehicle Body, Changsha 410082, Peoples R China.
通讯机构：
[Cao, YL ] U;Univ South China, Sch Mech Engn, Hengyang 421001, Peoples R China.
关键词：
Gas foil bearing;Stacked perforated foils;Theoretical model;Static and dynamic characteristics
摘要：
this paper presents a stacked perforated foil bearing to address plastic deformation and complex processes of traditional gas foil bearing, which consists of a top foil, three stacked perforated foils and a bearing sleeve. Three layers of perforated foils are stacked to form a stacked perforated foils as the elastic structure of the SPFB, providing sufficient structural deformation and multi-point friction. The theoretical model of the SPFB, which couples a structural model based on a single supported beam with Reynolds equation, is solved using FDM, and the predicted results are validated against experimental results. The static and dynamic characteristics of the SPFB are analyzed under multiple structural and operational parameters, which improves the theoretical basis for commercial application.
作者机构：
[Xie, Guizhong; Li, Hao; Du, Wenliao; Zhong, Yudong; Jia, Hangqi; Wang, Liangwen] Zhengzhou Univ Light Ind, Mech & Elect Engn Inst, Henan Prov Key Lab Intelligent Mfg Mech, Zhengzhou 450002, Henan, Peoples R China.;[Dong, Yunqiao] Univ South China, Sch Mech Engn, Hengyang 421001, Peoples R China.;[Lv, Jiahe] China Univ Geosci, Fac Engn, Wuhan 430074, Peoples R China.
通讯机构：
[Guizhong Xie; Hao Li] H;[Yunqiao Dong] S;Henan Provincial Key Laboratory of Intelligent Manufacturing of Mechanical, Mechanical and Electrical Engineering Institute, Zhengzhou University of Light Industry, Zhengzhou, Henan 450002, China<&wdkj&>School of Mechanical Engineering, University of South China, Hengyang 421001, China
关键词：
Life prediction;Neural network;Phase field method
摘要：
In this paper, a new method which combines the back-propagation artificial neural net-work and phase field method is proposed to predict the residual useful life of mechanical structures. Firstly, the phase field model of brittle fracture is constructed by phase-field method, and the data set about the corresponding strain value and lifespan of the me-chanical structure is obtained. Then, the data set is employed as the training samples by back-propagation artificial neural network to obtain the lifespan prediction mathematical model of mechanical structure. With the help of prediction model, only the corresponding structure strain value can be used to predict the remaining life of the structure. Finally, the prediction performance of the proposed method is evaluated by numerical examples. The results show that the proposed method combining the phase-field method and neural network technology for predicting the remaining life of the structure has high accuracy. (c) 2023 Elsevier Inc. All rights reserved.
作者机构：
[Xiao, Zhang; Liu, Junjie; Sun, Erjie] Univ South China, Coll Mech Engn, Hengyang 421001, Peoples R China.;[Du, Meng; Xiao, Zhang; Chen, Zhiyi] Univ South China, Inst Med Imaging, Hengyang Med Sch, Hengyang 421001, Peoples R China.;[Du, Meng; Chen, Zhiyi] Univ South China, Affiliated Hosp 1, Med Imaging Ctr, Hengyang Med Sch, Hengyang 421001, Peoples R China.;[Zhang, Jinke; Gong, Xiaojing] Chinese Acad Sci, Shenzhen Inst Adv Technol, Res Ctr Biomed Opt & Mol Imaging, Shenzhen Key Lab Mol Imaging,Guangdong Prov Key La, Shenzhen 518055, Peoples R China.;[Chen, Zhiyi] Univ South China, Affiliated Hosp 7, Hunan Vet Adm Hosp, Hengyang Med Sch, Changsha 410000, Peoples R China.
通讯机构：
[Xiaojing Gong; Zhiyi Chen] A;Authors to whom correspondence should be addressed.<&wdkj&>Institute of Medical Imaging, Hengyang Medical School, University of South China, Hengyang 421001, China<&wdkj&>The First Affiliated Hospital, Medical Imaging Centre, Hengyang Medical School, University of South China, Hengyang 421001, China<&wdkj&>The Seventh Affiliated Hospital, Hunan Veterans Administration Hospital, Hengyang Medical School, University of South China, Changsha 410000, China<&wdkj&>Authors to whom correspondence should be addressed.<&wdkj&>Research Center for Biomedical Optics and Molecular Imaging, Shenzhen Key Laboratory for Molecular Imaging, Guangdong Provincial Key Laboratory of Biomedical Optical Imaging Technology, CAS Key Laboratory of Health Informatics, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China
关键词：
optical coherence tomography;image segmentation;deep learning;mechanism of attention
摘要：
Optical coherence tomography (OCT) image processing can provide information about the uterine cavity structure, such as endometrial surface roughness, which is important for the diagnosis of uterine cavity lesions. The accurate segmentation of uterine cavity OCT images is a key step of OCT image processing. We proposed an EA-UNet-based image segmentation model that uses a U-Net network structure with a multi-scale attention mechanism to improve the segmentation accuracy of uterine cavity OCT images. The E(ECA-C) module introduces a convolutional layer combined with the ECA attention mechanism instead of max pool, reduces the loss of feature information, enables the model to focus on features in the region to be segmented, and suppresses irrelevant features to enhance the network’s feature-extraction capability and learning potential. We also introduce the A (Attention Gates) module to improve the model’s segmentation accuracy by using global contextual information. Our experimental results show that the proposed EA-UNet can enhance the model’s feature-extraction ability; furthermore, its MIoU, Sensitivity, and Specificity indexes are 0.9379, 0.9457, and 0.9908, respectively, indicating that the model can effectively improve uterine cavity OCT image segmentation and has better segmentation performance.
