检索结果-南通市图书馆

Filtering and regret network for spacecraft component segmentation based on gray images and depth maps

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2024年第7期37卷 439-449页

作者： Xiang LIU Hongyuan WANG Zijian WANG Xinlong chen Weichun chen Zhengyou XIE Institute of Aeronautics Harbin Institute of TechnologyHarbin 150001China Qian Xuesen Laboratory of Space Technology China Academy of Space TechnologyBeijing 100080China

Identifying and segmenting spacecraft components is vital in many on-orbit space missions,such as on-orbit maintenance and component *** depth maps with visual images has been proven effective in improving segmentation ***,existing methods ignore the noise and fallacy in collected depth maps,which interfere with the network to extract representative features,decreasing the final segmentation *** this end,this paper proposes a Filtering and Regret Network(FRNet)for spacecraft component *** FRNet incorporates filtering and regret mechanisms to suppress the abnormal depth response in shallow layers and selectively reuses the filtered cues in deep layers,avoiding the detrimental effects of low-quality depth information while preserving the semantic context inherent in depth ***,a two-stage feature fusion module is proposed,which involves information interaction and *** module effectively explores the feature correlation and unifies the multimodal features into a comprehensive ***,a large-scale spacecraft component recognition dataset is constructed for training and evaluating spacecraft component segmentation *** results demonstrate that the FRNet achieves a state-of-the-art performance with a mean Intersection Over Union(mIOU)of 84.13%and an average inference time of 133.2 ms when tested on an NVIDIA RTX 2080 SUPER GPU.

关键词： Spacecraft component recognition Multi-modal feature fusion Satellite dataset Intelligent systems Deep learning

Study of poly-disperse aerosols deposition in turbulent flow with different Reynolds numbers

在线全文

学校读者我要写书评

暂无评论

Particuology 2024年第6期89卷 32-43页

作者： Zhichao Gao Yongzheng chen Dandi Zhang Peng chen Lili Tong Xuewu Cao School of Mechanical Engineering Shanghai Jiao Tong UniversityShanghai200240China China Nuclear Power Technology Research Institute Co. Ltd.Shenzhen518000China

The turbulent deposition mechanism is one of the main mechanisms of aerosol deposition in nuclear power plant *** experimental study of poly-disperse aerosol deposition in a horizontal tube is conducted,where the nominal Reynolds number(Re)is in a range of 3600–200,*** aerosol deposition velocity first increases and then decreases with the increase of Res,and at high Re,particle rebound occurs during aerosol deposition in the *** the Re is low,the aerosol deposition velocity increases with the increase of aerosol *** the Re is greater than 60,000,the deposition velocity first increases and then decreases with the increase of aerosol diameter due to particle surface rebound.A new aerosol deposition model has been developed by establishing the energy conservation equation of the rebounded particles in the viscous *** calculated results of the new model are in good agreement with these experimental results,and the error between the aerosol deposition velocity calculated by the model and experimental results is between−60%and 150%.

关键词： Aerosol Turbulent deposition Rebound High Reynolds number

Application Analysis of Multiple Neurons Connected with Fast Inhibitory Synapses

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Bionic Engineering 2024年第4期21卷 1905-1918页

作者： Wen Duan Weihai chen Jianhua Wang Zhongcai Pei Jingmeng Liu Jianer chen School of Automation Science and Electrical Engineering Beihang UniversityXueyuan RoadBeijing100191China Hangzhou Innovation Institute Beihang UniversityChuanghui StreetHangzhou310051ZhejiangChina School of Electrical Engineering and Automation Anhui UniversityAnhui230601ZhejiangChina Zhejiang Rehabilitation Medical Center Binsheng RoadHangzhou310052ZhejiangChina

Almost all living organisms exhibit autonomic oscillatory activities,which are primarily generated by the rhythmic activities of their neural *** nonlinear oscillator models have been proposed to elucidate these neural behaviors and subsequently applied to the domain of robot ***,the oscillation patterns generated by these models are often unpredictable and need to be obtained through parameter *** study introduces a mathematical model that can be used to analyze multiple neurons connected through fast inhibitory *** characteristic of this oscillator is that its stationary point is stable,but the location of the stationary point changes with the system *** through reasonable topology and threshold parameter selection can the oscillation be *** study analyzed the conditions for stable oscillation in two-neuron networks and three-neuron networks,and obtained the basic rules of the phase relationship of the oscillator network established by this *** addition,this study also introduces synchronization mechanisms into the model to enable it to be synchronized with the sensing ***,this study used these theories to establish a robot single leg joint angle generation *** experimental results showed that the simulated robot could achieve synchronization with human motion,and had better control effects compared to traditional oscillators.

关键词： Oscillator Phase trajectory Synaptic threshold Synchronization Motion generation

Vibration-assisted vat photopolymerization for pixelated-aliasing-free surface fabrication

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

International Journal of Extreme Manufacturing 2024年第3期6卷 440-456页

作者： Han Xu Renzhi Hu Shuai chen Junhong Zhu Chi Zhou Yong chen Center for Advanced Manufacturing University of Southern CaliforniaLos AngelesCA 90007United States of America Daniel J.Epstein Department of Industrial and Systems Engineering University of Southern CaliforniaLos AngelesCA 90089United States of America Department of Aerospace and Mechanical Engineering University of Southern CaliforniaLos AngelesCA 90089United States of America Department of Industrial and Systems Engineering University of BuffaloBuffaloNY 14260United States of America

Mask image projection-based vat photopolymerization(MIP-VPP)offers advantages like low cost,high resolution,and a wide material range,making it popular in industry and ***,MIP-VPP employing liquid crystal displays(LCDs)has gained traction,increasingly replacing digital micromirror devices,particularly among hobbyists and in educational settings,and is now beginning to be used in industrial ***,LCD-based MIP-VPPsuffers from pronounced pixelated aliasing arising from LCD’s discrete image pixels and itsdirect-contact configuration in MIP-VPP machines,leading to rough surfaces on the 3D-printed ***,we propose a vibration-assisted MIP-VPP method that utilizes a microscalevibration to uniformize the light intensity distribution of the LCD-based mask image on VPP’s building *** maintaining the same fabrication speed,our technique generates asmoother,non-pixelated mask image,reducing the roughness on flat surfaces and boundary segments of 3D-printed *** light intensity modeling and simulation,we derived an optimal vibration pattern for LCD mask images,subsequently validated by *** assessed the surface texture,boundary integrity,and dimensional accuracy of componentsproduced using the vibration-assisted *** notably smoother surfaces and improved boundary roughness enhance the printing quality of MIP-VPP,enabling its promisingapplications in sectors like the production of 3D-printed optical devices and others.

关键词： additive manufacturing vat photopolymerization piezo vibration sub-pixel resolution aliasing

Single-Ni-atoms on nitrogenated humic acid based porous carbon for CO_(2) electroreduction

在线全文

学校读者我要写书评

暂无评论

Frontiers of Chemical Science and Engineering 2024年第5期18卷 37-47页

作者： Delei Yu Ying chen Yao chen Xiangchun Liu Xianwen Wei Ping Cui Anhui Key Laboratory of Coal Clean Conversion&Utilization School of Chemistry and Chemical EngineeringAnhui University of TechnologyMa’anshan 243002Chin

tWe proposed a facile synthesis of single-Ni-atom catalysts on low-cost porous carbon using a calcina-tion method at the temperatures of 850-1000°C,which were used for CO_(2) electrochemical reduction to *** porous carbon was prepared by carbonizing cheap and abundant humic *** structural characterizations of the as-synthesized catalysts and their electrocatalytic performances were *** results showed that the single-Ni-atom catalyst activated at 950°C showed an optimum catalytic performance,and it reached a CO Faradaic efficiency of 91.9% with a CO partial current density of 6.9 mAcm^(-2)at-0.9 V *** hydrogen electrode(RHE).Additionally,the CO Faradaic efficiency and current density of the optimum catalyst changed slightly after 8 h of continuous operation,suggesting that it possessed an excellent *** structure-activity relations indicate that the variation in the CO_(2) electroche-mical reduction performance for the as-synthesized catalysts is ascribed to the combined effects of the increase in the content of pyrrolic N,the evaporation of Ni and N,the decrease in pore volume,and the change in graphitization degree.

关键词： CO_(2) electroreduction single-Ni-atom cataly-sts humic acid based porous carbon

Impact Force Localization and Reconstruction via ADMM-based Sparse Regularization Method

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Journal of Mechanical Engineering 2024年第3期37卷 170-188页

作者： Yanan Wang Lin chen Junjiang Liu Baijie Qiao Weifeng He Xuefeng chen National Key Lab of Aerospace Power System and Plasma Technology Xi’an Jiaotong UniversityXi’an 710049China School of Mechanical Engineering Xi’an Jiaotong UniversityXi’an 710049China

In practice,simultaneous impact localization and time history reconstruction can hardly be achieved,due to the illposed and under-determined problems induced by the constrained and harsh measuring *** l_(1) regularization can be used to obtain sparse solutions,it tends to underestimate solution amplitudes as a biased *** address this issue,a novel impact force identification method with l_(p) regularization is proposed in this paper,using the alternating direction method of multipliers(ADMM).By decomposing the complex primal problem into sub-problems solvable in parallel via proximal operators,ADMM can address the challenge *** mitigate the sensitivity to regularization parameters,an adaptive regularization parameter is derived based on the K-sparsity ***,an ADMM-based sparse regularization method is developed,which is capable of handling l_(p) regularization with arbitrary p values using adaptively-updated *** effectiveness and performance of the proposed method are validated on an aircraft skin-like composite ***,an investigation into the optimal p value for achieving high-accuracy solutions via l_(p) regularization is *** turns out that l_(0.6)regularization consistently yields sparser and more accurate solutions for impact force identification compared to the classic l_(1) regularization *** impact force identification method proposed in this paper can simultaneously reconstruct impact time history with high accuracy and accurately localize the impact using an under-determined sensor configuration.

关键词： Impact force identification Non-convex sparse regularization Alternating direction method of multipliers Proximal operators

Uncertainty quantification of mechanism motion based on coupled mechanism—motor dynamic model for ammunition delivery system

在线全文

学校读者我要写书评

暂无评论

Defence Technology（防务技术） 2024年第3期33卷 125-133页

作者： Jinsong Tang Linfang Qian Longmiao chen Guangsong chen Mingming Wang Guangzu Zhou Nanjing University of Science and Technology Nanjing 210094China Northwest Institute of Mechanical and Electrical Engineering Xianyang 712099China

In this paper,a dynamic modeling method of motor driven electromechanical system is presented,and the uncertainty quantification of mechanism motion is investigated based on this *** main contribution is to propose a novel mechanism-motor coupling dynamic modeling method,in which the relationship between mechanism motion and motor rotation is established according to the geometric coordination of the *** advantages of this include establishing intuitive coupling between the mechanism and motor,facilitating the discussion for the influence of both mechanical and electrical parameters on the mechanism,and enabling dynamic simulation with controller to take the randomness of the electric load into *** simulation considering feedback control of ammunition delivery system is carried out,and the feasibility of the model is verified *** on probability density evolution theory,we comprehensively discuss the effects of system parameters on mechanism motion from the perspective of uncertainty *** work can not only provide guidance for engineering design of ammunition delivery mechanism,but also provide theoretical support for modeling and uncertainty quantification research of mechatronics system.

关键词： Ammunition delivery system Electromechanical coupling dynamics Uncertainty quantification Generalized probability density evolution

The association and underlying mechanism of the digit ratio(2D:4D)in hypospadias

在线全文

学校读者我要写书评

暂无评论

Asian Journal of Andrology 2024年第4期26卷 356-365页

作者： Yu Ding Zu-Quan chen Wen-Feng Pan Hao-Jie chen Min Wu Yi-Qing Lyu Hua Xie Yi-chen Huang Zhong-Zhong chen Fang chen Department of Urology Shanghai Children’s HospitalSchool of MedicineShanghai Jiao Tong UniversityShanghai 200062China Urogenital Development Research Center Shanghai Children’s HospitalSchool of MedicineShanghai Jiao Tong UniversityShanghai 200062China Clinical Research Center for Hypospadias Pediatric CollegeShanghai Jiao Tong University School of MedicineShanghai 200062China.

The second-to-fourth digit(2D:4D)ratio is thought to be associated with prenatal androgen ***,the relationship between the 2D:4D ratio and hypospadias is poorly understood,and its molecular mechanism is not *** this study,by analyzing the hand digit length of 142 boys with hypospadias(23 distal,68 middle,and 51 proximal)and 196 controls enrolled in Shanghai Children’s Hospital(Shanghai,China)from December 2020 to December 2021,we found that the 2D:4D ratio was significantly increased in boys with hypospadias(P<0.001)and it was positively correlated with the severity of the *** was further verified by the comparison of control mice and prenatal low testosterone mice model obtained by knocking out the risk gene(dynein axonemal heavy chain 8[DNAH8])associated with ***,the discrepancy was mainly caused by a shift in *** characterization of a mouse model validated that low testosterone levels during pregnancy can impair the growth and development of *** mechanistic explorations revealed that during the androgen-sensitive window,the downregulation of the androgen receptor(AR)caused by low testosterone levels,as well as the suppressed expression of chondrocyte proliferation-related genes such as Wnt family member 5a(Wnt5a),Wnt5b,Smad family member 2(Smad2),and Smad3;mitochondrial function-related genes in cartilage such as AMP-activated protein kinase(AMPK)and nuclear respiratory factor 1(Nrf-1);and vascular development-related genes such as myosin light chain(MLC),notch receptor 3(Notch3),and sphingosine kinase 1(Sphk1),are responsible for the limitation of 4D growth,which results in a higher 2D:4D ratio in boys with hypospadias via decreased endochondral *** study indicates that the ratio of 2D:4D is a risk marker of hypospadias and provides a potential molecular mechanism.

关键词： androgen receptor digit ratio(2D:4D) endochondral ossification hypospadias testosterone level

Molecular investigation into the transformation of recalcitrant dissolved organic sulfur in refinery sour water during stripping process

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Petroleum Science 2024年第3期21卷 2112-2119页

作者： Yu-Guo Li chen He Chun-Mao chen Fan Liu Quan Shi State Key Laboratory of Heavy Oil Processing China University of PetroleumBeijing 102249China State Key Laboratory of Coal Mining and Clean Utilization Beijing 100013China PetroChina Ningxia Petrochemical Company Yinchuan 750021NingxiaChina

Refinery sour water primarily originates from the tops of towers in various units and coker condensate,and cannot be discharged directly to a wastewater treatment plant due to high levels of chemical oxygen demand(COD)and organic sulfur *** after the recovery of H_(2)S from the sour water by the stripping process,the effluent still contains a high concentration of dissolved organic sulfur(DOS),which can have a huge bad *** chemical composition of dissolved organic matter(DOM)in refinery wastewater has been extensively studied,the investigation of recalcitrant DOS from sour waters remains *** the present study,chemical composition of sour water DOMs(especially DOS)was investigated using fluorescence spectroscopy(excitation-emission matrix,EEM)and mass spectrometry,including gas chromatography-mass spectrometry(GC-MS)and high-resolution Orbitrap *** GC-MS and EEM results showed that volatile and low-aromaticity compounds were effectively removed during the stripping process,while compounds with high hydrophilicity and humification degree were found to be more *** Orbitrap MS results showed that weak-polar oxygenated sulfur compounds were easier to be removed than oxygenated ***,the effluent still contained significant amounts of sulfur-containing compounds with multiple sulfur atoms,particularly in the form of highly unsaturated and aromatic *** Orbitrap MS/MS results of CHOS-containing compounds from the effluent indicate that the sulfur atoms may exist as sulfonates,disulfide bonds,*** the composition and structure of sour water DOS is crucial for the development of effective treatment processes that can target polysulfide compounds and minimize their impact on the environment.

关键词： Molecular transformation Dissolved organic sulfur Stripping process Refinery sourwater Orbitrap MS