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On Robust Cross-view Consistency in Self-supervised Monocular Depth Estimation

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Machine Intelligence Research 2024年第3期21卷 495-513页

作者： Haimei zhao Jing Zhang Zhuo Chen bo Yuan Dacheng Tao School of Computer Science University of SydneySydney2008Australia Shenzhen International Graduate School Tsinghua UniversityShenzhen518055China School of Information Technology&Electrical Engineering University of QueenslandBrisbane4072Australia

Remarkable progress has been made in self-supervised monocular depth estimation (SS-MDE) by exploring cross-view consistency, e.g., photometric consistency and 3D point cloud consistency. However, they are very vulnerable to illumination variance, occlusions, texture-less regions, as well as moving objects, making them not robust enough to deal with various scenes. To address this challenge, we study two kinds of robust cross-view consistency in this paper. Firstly, the spatial offset field between adjacent frames is obtained by reconstructing the reference frame from its neighbors via deformable alignment, which is used to align the temporal depth features via a depth feature alignment (DFA) loss. Secondly, the 3D point clouds of each reference frame and its nearby frames are calculated and transformed into voxel space, where the point density in each voxel is calculated and aligned via a voxel density alignment (VDA) loss. In this way, we exploit the temporal coherence in both depth feature space and 3D voxel space for SS-MDE, shifting the “point-to-point” alignment paradigm to the “region-to-region” one. Compared with the photometric consistency loss as well as the rigid point cloud alignment loss, the proposed DFA and VDA losses are more robust owing to the strong representation power of deep features as well as the high tolerance of voxel density to the aforementioned challenges. Experimental results on several outdoor benchmarks show that our method outperforms current state-of-the-art techniques. Extensive ablation study and analysis validate the effectiveness of the proposed losses, especially in challenging scenes. The code and models are available at https://***/sunnyHelen/RCVC-depth.

关键词： 3D vision depth estimation cross-view consistency self-supervised learning monocular perception

Robust fixed-time flight controller for a dual-system convertible UAV in the cruise mode

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Defence Technology（防务技术） 2024年第9期39卷 53-66页

作者： Lulu Chen Zhenbao Liu Qingqing Dang wen zhao wenyu Chen School of Civil Aviation Northwestern Polytechnical UniversityXi'an 710072China Shenzhen Research Institute of Northwestern Polytechnical University Shenzhen 518057China Air and Missile Defense College Air Force Engineering UniversityXi'an 710051China

This paper investigates the attitude tracking control problem for the cruise mode of a dual-system convertible unmanned aerial vehicle(UAV)in the presence of parameter uncertainties,unmodeled uncertainties and wind ***,a fixed-time disturbance observer(FXDO)based on the bi-limit homogeneity theory is designed to estimate the lumped disturbance of the convertible UAV ***,a fixed-time integral sliding mode control(FXISMC)is combined with the FXDO to achieve strong robustness and chattering ***-limit homogeneity theory and Lyapunov theory are applied to provide detailed proof of the fixed-time ***,numerical simulation experimental results verify the robustness of the proposed algorithm to model parameter uncertainties and wind *** addition,the proposed algorithm is deployed in a open-source UAV autopilot and its effectiveness is further demonstrated by hardware-in-the-loop experimental results.

关键词： Convertible UAV Flight control Disturbance observer Fixed-time control

Hydromassage of macular hole edges for large and persistent full-thickness macular holes

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International Journal of Ophthalmology(English edition) 2024年第3期17卷 551-557页

作者： Yi Cai wen-bo Liu Duo Wei Xun Deng Xiao-Xin Li Ming-Wei zhao Xuan Shi Jian-Hong Liang Department of Ophthalmology Peking University People’s HospitalBeijing 100044China Eye Diseases and Optometry Institute Beijing 100044China Beijing Key Laboratory of Diagnosis and Therapy of Retinal and Choroid Diseases Beijing 100044China College of Optometry Peking University Health Science CenterBeijing 100044China Xiamen Eye Center of Xiamen University Xiamen 361102Fujian ProvinceChina Department of Ophthalmology the Second Hospital of Lanzhou UniversityLanzhou 730030Gansu ProvinceChina

●AIM:To introduce the macular hole(MH)hydromassage technique as a potentially beneficial approach for the treatment of large or persistent MH.●METHODS:This retrospective observational case series comprised 16 consecutive patients(17 eyes)diagnosed with *** criteria involved a hole aperture diameter larger than 600μm or the presence of an unclosed MH larger than 600μm following the previous *** MH repair procedures were administered in all cases,involving the manipulation and aspiration of the hole margin through the application of water flow with a soft-tip flute needle.A comprehensive assessment was conducted for each case before and after surgery,and optical coherence tomography(OCT)images were captured at every follow-up point.●RESULTS:The mean preoperative aperture diameter was 747±156μm(range 611-1180μm),with a mean base diameter of 1390±435μm(range 578-2220μm).Following surgery,all cases achieved complete anatomical closure of MH,with 13 cases(76.5%)exhibiting type 1 closure and 4 cases(23.5%)demonstrating type 2 *** significant differences were observed in the preoperative OCT variables between the two closure *** with type 1 closure showed a significantly improved visual acuity(0.70±0.10,range 0.50-0.80)compared to those with type 2 closure(0.90±0.12,range 0.80-1.00,P=0.014).●CONCLUSION:The MH hydromassage technique demonstrates promising results,achieving acceptable closure rates in cases of large or persistent *** technique may serve as an effective adjunctive maneuver during challenging MH surgery.

关键词： macular hole large macular hole persistent macular hole optical coherence tomography surgical technique hydromassage

The design and engineering strategies of metal tellurides for advanced metal-ion batteries

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Journal of Energy Chemistry 2024年第2期89卷 579-598,I0013页

作者： wenmiao zhao Xiaoyuan Shi bo Liu Hiroshi Ueno Ting Deng Weitao Zheng Key Laboratory of Automobile Materials of MOE School of Materials Science and EngineeringJilin Provincial International Cooperation Key Laboratory of High-Efficiency Clean Energy MaterialsJilin UniversityChangchun 130012JilinChina Key Laboratory of Polyoxometalate Science of Ministry of Education Northeast Normal UniversityChangchun 130024JilinChina Key Laboratory of Preparation and Application of Environmental Friendly Materials(Jilin Normal University) Ministry of EducationChangchun 130103JilinChina Creative Interdisciplinary Research Division The Frontier Research Institute for Interdisciplinary Sciences(FRIS)Department of ChemistryGraduate School of ScienceTohoku UniversitySendai 980-8578Japan

Owning various crystal structures and high theoretical capacity,metal tellurides are emerging as promising electrode materials for high-performance metal-ion batteries(MBs).Since metal telluride-based MBs are quite new,fundamental issues raise regarding the energy storage mechanism and other aspects affecting electrochemical *** volume expansion,low intrinsic conductivity and slow ion diffusion kinetics jeopardize the performance of metal tellurides,so that rational design and engineering are crucial to circumvent these ***,this review provides an in-depth discussion of recent investigations and progresses of metal tellurides,beginning with a critical discussion on the energy storage mechanisms of metal tellurides in various *** the following,recent design and engineering strategies of metal tellurides,including morphology engineering,compositing,defect engineering and heterostructure construction,for high-performance MBs are *** primary focus is to present a comprehensive understanding of the structural evolution based on the mechanism and corresponding effects of dimension control,composition,electron configuration and structural complexity on the electrochemical *** closing,outlooks and prospects for future development of metal tellurides are *** work also highlights the promising directions of design and engineering strategies of metal tellurides with high performance and low cost.

关键词： Metal tellurides Metal-ion battery Energy storage mechanism Material design and engineering

Effect of Incoming Vortex on Secondary Flows in Turbine Cascades with Planar and Non-Axisymmetric Endwall

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Journal of Thermal Science 2024年第1期33卷 138-157页

作者： CAO Zhiyuan WANG Chuxuan SONG Zhigao GAO Xi zhao Wei LIU bo School of Power and Energy Northwestern Polytechnical UniversityXi'an 710072China National Key Laboratory of Science and Technology on Aerodynamic Design and Research Northwestern Polytechnical UniversityXi'an 710072China Institute of Engineering Thermophysics Chinese Academy of SciencesBeijing 100080China School of Aeronautics and Astronautics University of Chinese Academy of SciencesBeijing 100080China

Non-Axisymmetric Endwall Profiling(NAEP) is commonly utilized in turbines to eliminate secondary ***,most of the NAEP methods consider a single-blade row environment without incorporating the effect of the stage *** paper aims to investigate the influence mechanism of the incoming vortex on the endwall secondary flow structures of NAEP in a highly loaded turbine *** model the incoming vortex in a stage environment,this study considers a half-delta wing as the vortex generator at the upstream of the turbine *** NAEP is then carried out for a highly loaded turbine cascade with an in-house numerical optimization design platform subject to no incoming *** simulation is also carried out under the influence of the incoming vortex for the turbine cascades with both planar and non-axisymmetric *** paper furthers investigated the pitchwise effect of the incoming vortex on the near endwall secondary *** results indicate that the NAEP effectively improves the endwall secondary flow of the turbine cascade,where the total pressure loss coefficient and the secondary kinetic energy(SKE) are reduced by 7.3%,and 45.7%,*** is further seen that with the incoming vortex,the NAEP achieves a considerable control effect on the endwall secondary flow of the turbine *** incoming vortex,the NAEP can still achieve considerable control effect on the endwall secondary flow of the turbine cascade;the averaged reductions of loss coefficient and SKE are 7.8% and 14.2%,*** some pitchwise locations,incoming vortex can suppress the convection of cross-passage flow toward the suction corner greatly and reduce the loss coefficient of the baseline *** incoming vortex at 4/7 pitch impinged right at the blade leading edge,leading to the generation of low-momentum fluid,which increased the size and the strength of the horseshoe *** all the pitchwise locations,NAEP can suppress the seco

关键词： non-axisymmetric endwall secondary flow incoming vortex passage vortex stage environment

Investigation of hydroxyl-terminated polybutadiene propellant breaking characteristics and mechanism impacted by submerged cavitation water jet

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Defence Technology（防务技术） 2024年第3期33卷 559-572页

作者： wenjun Zhou Meng zhao bo Liu Youzhi Ma Youzhi Zhang Xuanjun Wang Zhijian Laboratory Rocket Force University of EngineeringXi’an710025China

A submerged cavitation water jet(SCWJ)is an effective method to recycle solid propellant from obsolete solid engines by the breaking *** propellant's breaking modes and mechanical process under SCWJ impact are *** study aims to understand those impact breaking *** hydroxyl-terminated polybutadiene(HTPB)propellant was chosen as the research material,and a self-designed test system was used to conduct impact tests at four different working *** high-speed camera characterized crack propagation,and the DIC method calculated strain change during the impact ***,micro and macro fracture morphologies were characterized by scanning electron microscope(SEM)and computed tomography(CT)*** results reveal that the compressive strain concentration region locates right below the nozzle,and the shear strain region distributes symmetrically with the jet axis,which increases to 4% at first 16th ms,the compressive strain rises to 2% and 6% in the axial and transverse direction,*** two tensile cracks formed first at the compression strain concentrate region,and there generate many shear cracks around the tensile cracks,and those shear cracks that develop and aggregate cause the cracks to become wider and cut through the tensile cracks,forming the tensile-shear cracks and the impact parts eventually *** HTPB propellant forms a breaking hole shaped conical after impact 10 *** mass loss increases by 17 times at maximum,with the working pressure increasing by three ***,the damage value of the breaking hole remaining on the surface increases by 7.8 times while 2.9 times in the depth of the breaking *** breaking efficiency is closely affected by working *** failure modes of HTPB impacted by SCWJ are classified as tensile crack-dominated and tensile-shear crack-dominated damage mechanisms.

关键词： Submerged cavitation water jet Hydroxyl-terminated polybutadiene propellant Breaking characteristics Failure modes

Study of deep transportation and plugging performance of deformable gel particles in porous media

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Petroleum Science 2024年第2期21卷 962-973页

作者： wen-Jing zhao Jing Wang Zhong-Yang Qi Hui-Qing Liu National Key Laboratory of Petroleum Resources and Engineering China University of PetroleumBeijing102249China MOE Key Laboratory of Petroleum Engineering China University of PetroleumBeijing102249China

Deformable gel particles(DGPs) possess the capability of deep profile control and flooding. However, the deep migration behavior and plugging mechanism along their path remain unclear. Breakage, an inevitable phenomenon during particle migration, significantly impacts the deep plugging effect. Due to the complexity of the process, few studies have been conducted on this subject. In this paper, we conducted DGP flow experiments using a physical model of a multi-point sandpack under various injection rates and particle sizes. Particle size and concentration tests were performed at each measurement point to investigate the transportation behavior of particles in the deep part of the reservoir. The residual resistance coefficient and concentration changes along the porous media were combined to analyze the plugging performance of DGPs. Furthermore, the particle breakage along their path was revealed by analyzing the changes in particle size along the way. A mathematical model of breakage and concentration changes along the path was established. The results showed that the passage after breakage is a significant migration behavior of particles in porous media. The particles were reduced to less than half of their initial size at the front of the porous media. Breakage is an essential reason for the continuous decreases in particle concentration, size, and residual resistance coefficient. However, the particles can remain in porous media after breakage and play a significant role in deep plugging. Higher injection rates or larger particle sizes resulted in faster breakage along the injection direction, higher degrees of breakage, and faster decreases in residual resistance coefficient along the path. These conditions also led to a weaker deep plugging ability. Smaller particles were more evenly retained along the path, but more particles flowed out of the porous media, resulting in a poor deep plugging effect. The particle size is a function of particle size before inject

关键词： Physical simulation Deformable gel particle Breakage Particle size Residual resistance coefficient

Decohesion of graphene from a uniaxially-stretched substrate:Failure analysis of a frictional adhesive interface

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Friction 2024年第3期12卷 510-521页

作者： bo PENG Chaochen XU Qingao WANG Pei zhao Xiqiao FENG Qunyang LI AML Department of Engineering MechanicsTsinghua UniversityBeijing 100084China State Key Laboratory of Tribology in Advanced Equipment Tsinghua UniversityBeijing 100084China Center for X-Mechanics and Institute of Applied Mechanics Zhejiang UniversityHangzhou 310027China State Key Laboratory of Fluid Power and M

Composite structures consisting of two-dimensional(2D)materials deposited on elastic substrates have a wide range of potential applications in flexible *** such devices,robust 2D film/substrate interfacial adhesion is essential for their reliable performance when subjected to external thermal and mechanical *** better understand the strength and failure behavior of the 2D film/substrate interfaces,two types of graphene/polymer samples with distinct interfacial adhesion properties are fabricated and tested by uniaxially stretching the *** on the interfacial adhesion,two drastically different debonding rates are observed,i.e.,rapid snap-through debonding and more progressive crack *** by the experimental observation,we propose an improved shear-lag model with a trapezoidal-shaped cohesive zone to derive an analytical solution for the decohesion *** theoretical model reveals that the decohesion behavior of the frictional adhesive interface is governed by three dimensionless ***,the dimensionless length of the film essentially determines the decohesion rate;while the other two parameters affect the critical substrate strain to initiate *** fitting the experimental data with the theoretical model,the intrinsic adhesion properties of the two samples are obtained with physically meaningful *** work offers an analytical solution to describing the decohesion behavior of general thin film/substrate systems with a frictional adhesive interface,which is beneficial for characterizing and optimizing the mechanical properties of various thin film/polymer devices.

关键词： film/substrate systems adhesion frictional sliding interface decohesion cohesive-zone model

Tribological and Corrosion Properties of the CoCrAlYTaSiC-xCNTs Coatings Deposited by Laser Cladding

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Acta Metallurgica Sinica(English Letters) 2024年第4期37卷 726-738页

作者： Hai zhao Yi Ding Wei Gao bo Yu Jinghui Li Mingya Zhang School of Material Science and Engineering Anhui University of TechnologyMaanshan243002China Maanshan Iron&Steel Co. LtdMaanshan243000China Applied Technology Research Institute Jiujiang Vocational UniversityJiujiang332000China School of Metallurgical Engineering Anhui University of TechnologyMaanshan243002China

The MCrAlY coating has been potential candidate for the parts applied in friction and corrosion conditions, and CNTs (carbon nanotubes) are expected to improve the service performance of coatings owing to high lubrication and low chemical reactivity. In this work, a systematic investigation on the tribological and corrosion properties of CoCrAlYTaSiC-xCNTs coatings deposited by laser melting was analyzed. Results showed that the coatings had good-quality without typical metallurgical defects. The CNTs addition homogenized and refined the microstructure of coating, and also improved the tribological and corrosion properties. As the CNTs content changed from 0 to 4 wt%, the wear rate of coating decreased from 16.23 × 10^(-3) to 7.58 × 10^(-3) mg m^(−1), the jcorr of coating decreased from 4.13 × 10^(-4) to 1.23 × 10^(-4) A cm^(−2), and the Rct values increased from 12.69 to 25.07 Ω cm2.

关键词： MCrAlY coating Laser melting deposition Friction Electrochemical corrosion