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.
