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Effect of Nozzle Inclination Angle on Fuel-Air Mixing and Combustion in a Heavy Fuel Engine

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Fluid Dynamics & Materials Processing 2024年第2期20卷 365-382页

作者： Zhigang Wang Bin Zheng Peidong Zhao Baoli Wang Fanyan Meng Wenke xu Jian Meng School of Transportation and Vehicle Engineering Shandong University of TechnologyZibo255049China

Heavy-fuel engines are widely used in UAVs(Unmanned Autonomous Vehicles)because of their reliability and high-power density.In this study,a combustion model for an in-cylinder direct injection engine has been imple-mented using the AVL FIRE software.The effects of the angle of nozzle inclination on fuel evaporation,mixture distribution,and combustion in the engine cylinder have been systematically studied at 5500 r/min and consider-ing full load cruise conditions.According to the results,as the angle of nozzle inclination increases,the maximum combustion explosion pressure in the cylinderﬁrst increases and then it decreases.When the angle of nozzle incli-nation is less than 45°,the quality of the mixture in the cylinder and the combustion performance can be improved by increasing the angle.When the angle of nozzle inclination is greater than 45°,however,the mixture unevenness increases slightly with the angle,leading to a deterioration of the combustion performances.When the angle of nozzle inclination is between 35°and 55°,the overall combustion performance of the engine is rela-tively good.When the angle of nozzle inclination is 45°,the combustion chamber’s geometry and the cylinder’s airﬂow are well matched with the fuel spray,and the mixture quality is the best.Compared with 25°,the peak heat release rate increases by 20%,and the maximum combustion burst pressure increases by 5.5%.

关键词： Aviation heavy fuel piston engine nozzle inclination angle combustion fuel-air mixing

A deep convolutional neural network for diabetic retinopathy detection via mining local and long-range dependence

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CAAI Transactions on Intelligence Technology 2024年第1期9卷 153-166页

作者： Xiaoling Luo Wei Wang Yong xu Zhihui Lai Xiaopeng Jin Bob Zhang David Zhang Shenzhen Key Laboratory of Visual Object Detection and Recognition Harbin Institute of TechnologyShenzhenChina Peng Cheng Laboratory ShenzhenChina Shenzhen Institute of Artificial Intelligence and Robotics for Society ShenzhenChina College of Big Data and Internet Shenzhen Technology UniversityShenzhenChina The Department of Computer and Information Science University of MacaoMacaoMacaoChina The Chinese University of Hong Kong(Shenzhen) ShenzhenChina

Diabetic retinopathy(DR),the main cause of irreversible blindness,is one of the most common complications of diabetes.At present,deep convolutional neural networks have achieved promising performance in automatic DR detection tasks.The convolution operation of methods is a local cross-correlation operation,whose receptive field de-termines the size of the local neighbourhood for processing.However,for retinal fundus photographs,there is not only the local information but also long-distance dependence between the lesion features(e.***.hemorrhages and exudates)scattered throughout the whole image.The proposed method incorporates correlations between long-range patches into the deep learning framework to improve DR detection.Patch-wise re-lationships are used to enhance the local patch features since lesions of DR usually appear as plaques.The Long-Range unit in the proposed network with a residual structure can be flexibly embedded into other trained networks.Extensive experimental results demon-strate that the proposed approach can achieve higher accuracy than existing state-of-the-art models on Messidor and EyePACS datasets.

关键词： image classification medical image processing pattern recognition

Monitoring Xylem Transport in the Stem of Lilium lancifolium Using Fluorescent Dye 5(6)-Carboxyfluorescein Diacetate

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Phyton-International Journal of Experimental Botany 2024年第5期93卷 1057-1066页

作者： Yulin Luo Panpan Yang Mengmeng Bi Leifeng xu Fang Du Jun Ming College of Horticulture Shanxi Agricultural UniversityJinzhong030801China State Key Laboratory of Vegetable Biobreeding Institute of Vegetables and FlowersChinese Academy of Agricultural SciencesBeijing100081China College of Urban and Rural Construction Shanxi Agricultural UniversityJinzhong030801China

The xylem undergoes physiological changes in response to various environmental conditions during the process of plant growth.To understand these physiological changes,it is extremely important to observe the transport of xylem.In this study,the distribution and structure of vascular bundle in Lilium lancifolium were observed using the method of semithin section.Methods for introducing a fluorescent tracer into the xylem of the stems were evaluated.Then,the transport rule of 5(6)-Carboxyfluorescein diacetate(CFDA)in the xylem of the stem of L.lancifolium was studied by fluorescence dye in live cells tracer technology.The results showed that the vascular bundles of L.lancifolium were scattered in the basic tissue,the peripheral vascular bundles were smaller and densely distributed,and the closer to the center,the larger the volume of vascular bundles and the more sparsely distributed.The vascular bundles of L.lancifolium are limited external tenacity vascular bundles,which are composed of phloem and xylem.The most suitable method for CFDA labeling the xylem of isolated stem segments of L.lancifolium was solution soaking for 24 h.The running speed of CF in the isolated stem was 0.3 cm/h,which was consistent with the running speed of the material in the field.CF could be transported between the xylem and parenchyma cells,indicating that the material transport in the xylem could be through the symplastic pathway.The above results laid a foundation for the study of the xylem transport mechanism and the xylem pathogen disease of lily.

关键词： Lilium xylem transport stem fluorescent dye CFDA

Design and experiment analysis of the small maize harvester with attitude adjustment in the hilly and mountainous areas of China

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International Journal of Agricultural and Biological Engineering 2024年第1期17卷 118-127页

作者： Meizhou Chen Guangfei xu Yuanzhen Wei Yinping Zhang Peisong Diao Huanxiao Pang College of Agricultural Engineering and Food Science Shandong University of TechnologyZibo255000ShandongChina School of Mechanical and Automotive Engineering Liaocheng UniversityLiaocheng252000ShandongChina Shandong Academy of Agricultural Machinery Sciences Jinan 250000China

To solve the problem of small planting plots and large sloping land for mechanized maize harvesting in China hilly and mountainous areas,a small maize harvester with attitude adjustment was designed to realize maize snapping,peeling,straw crushing and attitude adjusting at on time in this study.The basic structure and working principle of the small maize harvester were described,and the key components were designed as follows.The maize snapping device adopted the combination form of maize snapping plates and straw pulling rollers,and the gap of the straw pulling rollers can be adjusted to adapt to different maize varieties.Two pairs of peeling rollers formed a groove arrangement to improve peeling rate and reduced ear grain loss.The pressure feeding device mainly comprised drive chain and three grade pressure feeding rollers to increase the friction between ears and the peeling rollers,and help ears slide.The attitude adjustment advice was designed according to the high point stationary pursuit leveling method.When the attitude angle of the rack approached 0,the small maize harvester reached the level state.The actual range of attitude adjustment was obtained and the accuracy of static attitude adjustment was verified through attitude adjustment test.The influencing factors of ear loss rate and bract peeling rate were determined by orthogonal test,including the rotational speed of straw pulling rollers,peeling rollers and pressure feeding rollers.The mathematical regression model between the experimental factors and indicators was established by using Design Expert,and through the analysis variance to verify the significance of the evaluation indicators,the best combination of operation parameters was determined that the rotational speed of straw pulling rollers,peeling rollers and pressure feeding rollers were 1440 r/min,1535 r/min and 406 r/min.Under the optimal combination of the operation parameters,the ear loss rate and bract peeling rate were 1.33%and 93.98%.The design indicators of the small maize harveste

关键词： maize harvester hilly and mountains areas attitude adjustment anti rollover structure

Mechanism of a dual-phase Ti-Nb alloy exhibiting near-linear elastic deformation

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Rare Metals 2024年第5期43卷 2282-2289页

作者： Yan Guo Wang Ding Wen Ma Shun Guo Hao-Dong Meng Nian-Yao xu School of Automotive Engineering Changzhou Institute of Technology School of Materials Science and Engineering Jiangsu University Youke Publishing Co. Ltd China Grinm Group Co. Ltd

In this work, the underlying mechanism responsible for the near-linear elastic deformation behavior of a dual-phase Ti-Nb alloy consisting of β and a''phase with large recoverable strain was systematically elucidated.Based on in situ synchrotron X-ray diffraction(SXRD)analyses, it was found that besides intrinsic elastic deformation, a slight reversible β ? a''stress-induced martensitic(SIM) transformation, which proceeded in a consecutive mode under the retarding effect of micro-defects, took place during the near-linear elastic deformation.After unloading, a small amount of residual macroscopic strain remained in the specimen due to the incomplete reverse a''→ β transformation on unloading. The high near-linear elastic deformability of the cold drawing(CD)Ti-Nb alloy has been revealed to be attributed to the coupling actions of intrinsic elasticity as well as the consecutive and reversible β ? a''SIM transformation. Our research may contribute to a new avenue for the design and development of novel dual-phase Ti-based alloys with desirable elastic deformability.

关键词： Titanium alloys Dual-phase Near-linear elastic deformation Martensitic transformation

Analysis of Maximum Liquid Carrying Capacity Based on Conventional Tubing Plunger Gas Lift

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Energy Engineering 2024年第6期121卷 1521-1533页

作者： Yanqun Yu Wenhao xu Yahui Huangfu Jinhai Liu Bensheng Wang Kai Liu College of Mechanical and Electronic Engineering China University of Petroleum(East China)Qingdao266580China Energy Technology&Services Oil Production Services Company CNOOCTianjin300450China

China’s unconventional gas fields have a large number of low-productivity and low-efficiency wells, many of whichare located in remote and environmentally harsh mountainous areas. To address the long-term stable productionof these gas wells, plunger-lift technology plays an important role. In order to fully understand and accurately graspthe drainage and gas production mechanisms of plunger-lift, a mechanical model of plunger-liquid column uplift inthe plunger-lift process was established, focusing on conventional plunger-lift systems and representative wellboreconfigurations in the Linxing region. The operating casing pressure of the plunger-lift process and the calculationmethod for the maximum daily fluid production rate based on the work regime with the highest fluid recovery ratewere determined. For the first time, the critical flow rate method was proposed as a constraint for the maximumliquid-carrying capacity of the plunger-lift, and liquid-carrying capacity charts for conventional plunger-lift withdifferent casing sizes were developed. The results showed that for 23/8 casing plunger-lift, with a well depth ofshallower than 808 m, the maximum drainage rate was 33 m3/d;for 27/8 casing plunger-lift, with a well depth ofshallower than 742 m, the maximum drainage rate was 50.15 m3/d;for 31/2 casing plunger-lift, with a well depthof shallower than 560 m, the maximum drainage rate was 75.14 m3/d. This research provides a foundation for thescientific selection of plunger-lift technology and serves as a decision-making reference for developing reasonableplunger-lift work regimes.

关键词： Unconventional well conventional tubing string plunger gas lift critical flow rate liquid carry-over chart version

Impact of inter-turn short fault on winding insulation temperature rising characteristic in PMSG

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Coordinated Voltage Control of Distribution Network ConsideringMultiple Types of Electric Vehicles

Dianji yu Kongzhi xuebao/Electric Machines and Control 2024年第4期28卷 18-30页

作者： He, Yuling Li, Yong Zhang, Wen Bai, Yifan xu, Mingxing Wang, Xiaolong Department of Mechanical Engineering Hebei Engineering Research Center for Advanced Manufacturing & Intelligent Operation and Maintenance of Electric Power Machinery North China Electric Power University Baoding 071003 China

The winding insulation temperature rising characteristic was investigated before and after interturn short circuit (ITSC) in permanent magnet synchronous generators (PMSG). Firstly, the magnetic flux density, stator current, core loss and copper loss expressions in normal and ITSC conditions were deduced. Then three dimensional finite element analysis (FEA) models were established. The varied types of loss were calculated in the electromagnetic filed and imported into the temperature field to obtain the temperature distribution of winding insulation. Finally, the experiments were taken on the LR -5 prototype PMSG to measure the winding insulation temperature. The experiment results are good accorded with the theoretical analysis and FEA results. It is shown that the winding temperature will increase significantly acted by the shorted winding current under ITSC fault. The server ITSC fault degree is intensified, the higher winding insulation temperature will be. In addition, the deformation, strain and stress resulting from the uneven distribution of thermal load on the winding insulation will also intensify. The insulation at the nose end of the winding is prone to damage due to high temperatures. This can be addressed by improving the cooling and heat dissipation structure or applying a heat-resistant coating to enhance the reliability of the insulation at the nose end. © 2024 Editorial Department of Electric Machines and Control. All rights reserved.

关键词： Permanent magnets

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Energy Engineering 2024年第2期121卷 377-404页

作者： Liang Liu Guangda xu Yuan Zhao Yi Lu Yu Li Jing Gao State Grid Jibei Electric Power Research Institute(North China Electric Power Research Institute Co. Ltd.)Beijing100045China

The couple between the power network and the transportation network(TN)is deepening gradually with the increasing penetration rate of electric vehicles(EV),which also poses a great challenge to the traditional voltage control scheme.In this paper,we propose a coordinated voltage control strategy for the active distribution networks considering multiple types of EV.In the first stage,the action of on-load tap changer and capacitor banks,etc.,are determined by optimal power flow calculation,and the node electricity price is also determined based on dynamic time-of-use tariff mechanism.In the second stage,multiple operating scenarios of multiple types of EVs such as cabs,private cars and buses are considered,and the scheduling results of each EV are solved by building an optimization model based on constraints such as queuing theory,Floyd-Warshall algorithm and traffic flow information.In the third stage,the output power of photovoltaic and energy storage systems is fine-tuned in the normal control mode.The charging power of EVs is also regulated in the emergency control mode to reduce the voltage deviation,and the amount of regulation is calculated based on the fair voltage control mode of EVs.Finally,we test the modified IEEE 33-bus distribution system coupled with the 24-bus Beijing TN.The simulation results show that the proposed scheme can mitigate voltage violations well.

关键词： Electric vehicle transportation network voltage control queuing theory

Light-Mediated Spatiotemporally Dynamic Assembly of DNA Nanostructures in Living Cells Regulates Autophagy

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CCS Chemistry 2024年第6期6卷 1557-1570页

作者： Rui Zhang Pin Hu Yuwei xu Ziqing Wang Dayong Yang Chi Yao Frontiers Science Center for Synthetic Biology Key Laboratory of Systems Bioengineering(MOE)School of Chemical Engineering and TechnologyTianjin UniversityTianjin 300350 Department of Chemistry State Key Laboratory of Molecular Engineering of PolymersShanghai Key Laboratory of Molecular Catalysis and Innovative MaterialsCollege of Chemistry and MaterialsFudan UniversityShanghai 200438

The assembly of exogenous artificial architectures inside cells can regulate a series of biological events,which heavily relies on the development of spatiotemporally controlled molecular assembly systems.We herein report a designer deoxyribonucleic acid(DNA)nanostructure that enables light-mediated spatiotemporally dynamic assembly in living cells and consequently achieves efficient regulation of cell autophagy.The DNA nanostructure was constructed from i-motif moiety-containing branched DNA,photocleavable bond-containing linker,and tumor cell-targeting aptamer.After cellular uptake mediated by aptamers,under the spatiotemporal control of both UV light and late endosomal/lysosomal acidic environments,disassembly/reassembly of DNA nanostructure occurred via two rationally designed routes,generating microsized DNA assembly.As a result,autophagy was significantly enhanced with the increase of DNA assembly size.The enhanced autophagy showed an impact on related biological effects.Our system is expected to be a powerful tool for the regulation of intracellular events and cellular behaviors.

关键词： DNA nanotechnology DNA hydrogel self-assembly autophagy i-motif