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Advancing electrochemical drilling process via coupling of flow field and electric field in pulsating state generated by a novel tube tool

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Chinese Journal of Aeronautics 2024年第4期37卷 542-555页

作者： Liang CHENG Xiaolei CHEN Zhisen YE yongjun zhang State Key Laboratory of Precision Electronic Manufacturing Technology and Equipment Guangdong University of TechnologyGuangzhou 510006China Guangdong Key Laboratory of Advanced Manufacturing Technology of Marine Energy Equipment Guangdong University of TechnologyGuangzhou 510006China Guangzhou Key Laboratory of Nontraditional Machining and Equipment Guangdong University of TechnologyGuangzhou 510006China

This paper introduces an improvement to electrochemical drilling process by coupling flow field and electric field in pulsating state. A novel tube with half-wedged shape at the end(HW-tube) is prepared, with both sidewall and wedged part of the HW-tube insulated. Only the flat part is utilized to provide electric field for electrochemical drilling. By rotating the HW-tube, both flow field and electric field in pulsating state are generated, alternating in different positions within the inter-electrode gap(IEG). The pulsating flow field enhances the mass transfer process, while pulsating electric field disperses material dissolution process and distribution of electrolytic byproducts. Both pulsating fields are coupled at the same frequency, further enhancing the electrochemical drilling process. Simulation results indicate that both flow field and electric field in pulsating state are generated. Compared to the traditional tube, the HW-tube significantly reduces the number of residual particles in IEG, and this number is further reduced by increasing the rotation speed. Experimental results reveal that the surface quality and dimensional uniformity of small hole are improved with HW-tube. With feed rate of 2.22 mm/min, a small hole with diameter of 1.52± 0.017 mm is drilled, resulting in a surface roughness of 0.331 μm.

关键词： Small holes Electrochemical drilling Tools Pulsating flow field Pulsating electric field

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Plasma characteristics and material erosion mechanism in multi-channel wire electrical discharge machining

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Chinese Journal of Aeronautics 2024年第10期37卷 508-525页

作者： Guokang SU Chuanyun zhang Junfei LI Xiaolei CHEN Guixian LIU yongjun zhang State Key Laboratory of Precision Electronic Manufacturing Technology and Equipment Guangdong University of TechnologyGuangzhou 510006China Guangdong Key Laboratory of Advanced Manufacturing Technology of Marine Energy Equipment Guangdong University of TechnologyGuangzhou 510006China Guangzhou Key Laboratory of Nontraditional Machining Technology and Equipment Guangdong University of TechnologyGuangzhou 510006China School of Mechanical Engineering Xi’an Technological UniversityXi’an 710021China

Multi-channel wire electrical discharge machining(MC-WEDM)is an advanced and high-efficiency machining technology,but its material erosion mechanism remains *** this study,dual-channel wire electrical discharge machining was utilized as a case study to investigate the impact of the plunging current on both the plasma characteristics and material erosion under complex discharge *** analysis was conducted on the charged particles in the plasma,revealing that the plunging current can influence the trajectory of the plasma by modifying the selfmagnetic *** particle tracking method was employed to simulate the motion of electrons,revealing that in MC-WEDM,electrons exhibited a larger and more uniform *** evolution of the plasma within a single-pulse discharge was observed using high-speed photography technology,and the discharge signals collected from different channels were *** was observed that the plasma in MC-WEDM experienced more intense back-and-forth sweeping on the workpiece surface,facilitating the ejection of molten metal from the molten *** oscillating plasma exhibits a larger processing area and a more uniform distribution of energy,resulting in the formation of larger and shallower discharge ***,the influence of the amplitude and time point of the plunging current on the volume and area of the discharge craters was ***,MC-WEDM significantly reduced the occurrence of holes and micro-cracks and exhibited a thinner recast layer in the continuous discharge experiment.

关键词： Multi-channel WEDM Discharge observation Plunging current Plasma characteristics Material erosion Discharge crater

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Modified Sadowski formula-based model for the slope shape amplification effect under multistage slope blasting vibration

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International Journal of Mining Science and Technology 2024年第5期34卷 631-641页

作者： Xiaogang Wu Mingyang Wang Hao Lu yongjun zhang Wen Nie State Key Laboratory of Disaster Prevention&Mitigation of Explosion&Impact Army Engineering University of PLANanjing 210007China State Key Laboratory of Metal Mine Safety and Health Ma’anshan 243000China School of Civil Engineering Qingdao University of TechnologyQingdao 266520China

Blasting operations,which are crucial to open-pit mine production due to their simplicity and efficiency,require precise control through accurate vibration velocity *** conventional Sadowski formula mainly focuses on blast center distance but neglects the amplification effect of blasting vibration waves by terraced terrain,from which the calculated blasting vibration velocities are smaller than the actual values,affecting the safety of the *** address this issue,our model introduces the influences of slope and time into Sadowski formula to measure safety through blast vibration *** the northern section of the open-pit quartz mine in Jinchang City,Gansu Province,China,the data of a continuous blasting slope project are referred *** findings reveal a noticeable vibration amplification effect during blasting when a multi-stage slope platform undergoes a sudden cross-sectional change near the upper overhanging *** amplification vibration coefficient increases with height,while vibration waves within rocks decrease from bottom to ***,platforms without distinct crosssectional changes exhibit no pronounced amplification during *** addition,the vibration intensity decreases with distance as the rock height difference change *** results obtained by the proposed blast vibration displacement equation incorporating slope shape influence closely agree with real-world *** to Pearson correlation coefficient(PPMCC)analysis,the average accuracy rate of our model is 88.84%,which exceeds the conventional Sadowski formula(46.92%).

关键词： Multistage slope Slope shape influence factor Continuous blasting Sadowski formula Amplification effect

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Sparse representation scheme with enhanced medium pixel intensity for face recognition

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CAAI Transactions on Intelligence Technology 2024年第1期9卷 116-127页

作者： Xuexue zhang yongjun zhang Zewei Wang Wei Long Weihao Gao Bob zhang State Key Laboratory of Public Big Data Institute for Artificial IntelligenceCollege of Computer Science and TechnologyGuizhou UniversityGuiyangGuizhouChina Department of Computer and Information Science University of MacaoAvenida da UniversidadeTaipaMacaoChina

Sparse representation is an effective data classification algorithm that depends on the known training samples to categorise the test *** has been widely used in various image classification *** in sparse representation means that only a few of instances selected from all training samples can effectively convey the essential class-specific information of the test sample,which is very important for *** deformable images such as human faces,pixels at the same location of different images of the same subject usually have different ***,extracting features and correctly classifying such deformable objects is very ***,the lighting,attitude and occlusion cause more *** the problems and challenges listed above,a novel image representation and classification algorithm is ***,the authors’algorithm generates virtual samples by a non-linear variation *** method can effectively extract the low-frequency information of space-domain features of the original image,which is very useful for representing deformable *** combination of the original and virtual samples is more beneficial to improve the clas-sification performance and robustness of the ***,the authors’algorithm calculates the expression coefficients of the original and virtual samples separately using the sparse representation principle and obtains the final score by a designed efficient score fusion *** weighting coefficients in the score fusion scheme are set entirely ***,the algorithm classifies the samples based on the final *** experimental results show that our method performs better classification than conventional sparse representation algorithms.

关键词： computer vision face recognition image classification image representation

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Associations of Perchlorate,Nitrate,and Thiocyanate with Sex Hormones among Children:A Nationally Representative Cross-sectional Study in U.S.

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Biomedical and Environmental Sciences 2024年第6期37卷 666-671页

作者： Yiwen Wang Guodong Ding Peipei Hu yongjun zhang Department of Pediatrics Xinhua HospitalShanghai Jiao Tong University School of MedicineShanghai 200092China MOE-Shanghai Key Laboratory of Children’s Environmental Health Xinhua HospitalShanghai Jiao Tong University School of MedicineShanghai 200092China

Nitrates,thiocyanates,and perchlorates are ubiquitous in the environment and can be introduced to the public through various dietary and environmental ***,thiocyanates,and perchlorates mainly affect health via the sam... 详细信息

关键词： mechanism sectional perchlorate

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A Flexible Voltage Control Strategy Based on Stage-division for Microgrids

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Protection and Control of Modern Power Systems 2024年第3期9卷 60-69页

作者： yongjun zhang Kaidong Lin Wenyang Deng Di zhang Dongliang Xiao IEEE the South China University of Technology GuangzhouChina the Department of Electric Power South China University of TechnologyGuangzhouChina the School of Electric Power South China University of TechnologyGuangzhou 510640China

The occurrence of power flow reversal and off-limit of the voltage on common bus becomes more frequent because of the increasing penetration of renewable energy sources(RES)in *** guarantee the safe and stable operation,adjusting the power output of RES-based inverters to avoid the off-limit voltage is *** the apparent power characteristics of inverters,as well as the minimum participation of active power,a voltage control strategy based on stage division to be within the voltage limit is investigated in this *** the case of unknown demand and distribution of loads,the proposed control strategy is able to make full use of the apparent power to regulate voltage using simple calculations,while the performance in economical operation is *** results prove the effectiveness of the proposed method on the common bus off-limit voltage adjustment.

关键词： Off-limit voltage microgrids voltage control inverter stage division

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Consumer-branch Connectivity Identification of Low Voltage Distribution Networks Based on Data-driven Approach

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Protection and Control of Modern Power Systems 2024年第4期9卷 69-82页

作者： yongjun zhang Yingqi Yi Wenyang Deng Siliang Liu Lai Zhou Kaidong Lin Yongzhi Cai the School of Electric Power Engineering and Guangdong Key Laboratory of Clean Energy Technology South China Uni-versity of TechnologyGuangzhou 510641China the School of Elec-tric Power Engineering South China University of TechnologyGuangzhou 510641China the Guangzhou Panyu vocational and technical college Guangzhou 511483China the Metrology Center Guangdong Power Company Grid Qingyuan 511500China

Accurate topological information is crucial in supporting the coordinated operational requirements of source-load-storage in low-voltage distribution *** coverage of smart meters provides a database for low-voltage topology identification(LVTI).However,because of electricity theft,power line commu-nication crosstalk,and interruption of communication,the measurement data may be *** can seriously affect the performance of LVTI ***,this paper defines hidden errors and proposes an LVTI method based on layer-by-layer stepwise *** the first step,a multi-linear regression model is developed for consumer-branch connectivity identification based on the energy conservation *** the second step,a significance factor based on the t-test is proposed to modify the identification results by considering the hidden *** the third step,the regression model and significance threshold parameters are iteratively updated layer by layer to improve the recall rate of the final identification ***,simulations of a test system with 63 users are carried out,and the practical application results show that the proposed method can guarantee over 90%precision under the influence of hidden errors.

关键词： Data driven hidden error linear re-gression low voltage distribution network topology identification

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多视影像三维线云重建技术及其智能化发展展望

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测绘学报 2024年第6期53卷 1025-1036页

作者：魏东刘欣怡张永军武汉大学遥感信息工程学院湖北武汉430079

三维线云是具有几何结构与语义信息的三维线段集合,可以作为实景三维构建中高效的引导,控制与抽象表达元素,弥补点云的边缘描述缺陷与初始结构的缺失,是改变传统三维模型“一张皮”(不同对象相互粘连,难以指导空间分析与决策)的重要结... 详细信息

三维线云是具有几何结构与语义信息的三维线段集合,可以作为实景三维构建中高效的引导,控制与抽象表达元素,弥补点云的边缘描述缺陷与初始结构的缺失,是改变传统三维模型“一张皮”(不同对象相互粘连,难以指导空间分析与决策)的重要结构化特征。然而,如何从多视影像中重建好用的线云,将线云在实景三维中用好,一直是本领域的难点问题。本文回顾三维线云的发展,介绍相关的重建方法,分析存在的难点与不足;结合从数字化走向智能化的测绘科技转型背景,论述线云在实景三维中建什么,如何建与怎么用,对线云重建和应用的智能化发展予以介绍和展望,希望为实景三维重建与线云研究的相关人员提供参考。

关键词：三维线云实景三维三维重建智能化测绘多视影像

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Fermi Surface Nesting with Heavy Quasiparticles in the Locally Noncentrosymmetric Superconductor CeRh2As2

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Chinese Physics Letters 2024年第9期41卷 107-121页

作者： Yi Wu yongjun zhang Sailong Ju Yong Hu Yanen Huang Yanan zhang Huali zhang Hao Zheng Guowei Yang Evrard-Ouicem Eljaouhari Baopeng Song Nicholas C.Plumb Frank Steglich Ming Shi Gertrud Zwicknagl Chao Cao Huiqiu Yuan Yang Liu Center for Correlated Matter and School of Physics Zhejiang UniversityHangzhou 310058China Institute for Advanced Materials Hubei Normal UniversityHuangshi 435002China Swiss Light Source Paul Scherrer InstitutCH-5232 Villigen PSISwitzerland Institut for Mathematische Physik 38106 BraunschweigGermany Max Planck Institute for Chemical Physics of Solids 01187 DresdenGermany Collaborative Innovation Center of Advanced Microstructures Nanjing UniversityNanjing 210093China State Key Laboratory of Silicon Materials Zhejiang UniversityHangzhou 310058China

The locally noncentrosymmetric heavy fermion superconductor CeRh2As2 has attracted considerable interests due to its rich superconducting phases,accompanied by possible quadrupole density wave and pronounced antiferromagnetic *** understand the underlying physics,here we report measurements from highresolution angle-resolved *** results reveal fine splittings of the conduction bands related to the locally noncentrosymmetric structure,as well as a quasi-two-dimensional Fermi surface(FS)with strong 4𝑓*** FS shows signs of nesting with an in-plane vector q1=(π/α,π/α),which is facilitated by the heavy bands nearˉ𝑋arising from the characteristic conduction-X *** FS nesting provides a natural explanation for the observed antiferromagnetic spin fluctuations at(π/α,π/α),which might be the driving force for its unconventional *** experimental results can be reasonably explained by density functional theory plus dynamical mean field theory calculations,which can capture the strong correlation *** study not only provides spectroscopic signature of the key factors underlying the field-induced superconducting transition,but also uncovers the critical role of FS nesting and lattice Kondo effect in the underlying magnetic fluctuations.

关键词： symmetric Fermi conduction

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知识图谱约束深度网络的高分辨率遥感影像场景分类

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测绘学报 2024年第4期53卷 677-688页

作者：李彦胜吴敏郎张永军武汉大学遥感信息工程学院湖北武汉430079

得益于深度网络理论与方法的快速发展,深度网络逐渐成为遥感影像场景分类任务的主流技术。然而,现有基于深度网络的遥感影像场景分类方法高度依赖大量人工标记的训练样本,且无法有效融合利用遥感领域丰富的先验知识。为了提升领域知识... 详细信息

得益于深度网络理论与方法的快速发展,深度网络逐渐成为遥感影像场景分类任务的主流技术。然而,现有基于深度网络的遥感影像场景分类方法高度依赖大量人工标记的训练样本,且无法有效融合利用遥感领域丰富的先验知识。为了提升领域知识利用率同时降低标记样本依赖,本文提出了一种知识图谱引导深度网络学习的高分辨率遥感影像场景分类方法。首先,构建了一个包括领域内多种来源知识的土地覆盖概念知识图谱来更灵活便捷地应用领域先验知识。然后,通过知识图谱表示学习方法将土地覆盖概念知识图谱中的遥感场景语义类别表达为语义向量,形成遥感场景类别语义基准。在知识引导学习阶段,通过施加场景类别语义向量与深度网络浅层视觉特征向量的跨模态对齐约束引导深度网络的浅层部分更有效地学习不同类别遥感影像场景的共享特征,在深度网络深层部分则仍然通过场景类别标签引导学习不同遥感场景的判别特征。在测试阶段,完成优化的深度网络模型可以在不依赖任何先验知识的情况下完成高精度遥感影像场景分类。在目前公开的最大的遥感影像场景分类数据集上的试验结果表明,本文提出的知识引导学习方法相比现有方法在10%、30%、50%等不同训练样本比率下均可以获得最佳分类性能。在10%这一比率条件下,本文提出的知识引导学习方法相比基线深度网络在总体精度指标(OA)上能够得到5.11%的提升。

关键词：遥感影像场景分类土地覆盖概念知识图谱知识图谱表示学习知识图谱约束深度网络

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