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Tribological properties and tribomechanism of nickel nanoparticles in-situ synthesized in rapeseed oil

Friction 2024年第3期12卷 474-489页

作者： Wenya XU Guangbin YANG Shengmao ZHANG Jun XU Yujuan ZHANG Tianhua SUN Ningning SONG Laigui YU Pingyu ZHANG Engineering research Center for Nanomaterials Henan UniversityKaifeng 475004China State Key Laboratory of Tribology in Advanced equipment Tsinghua UniversityBeijing 100084China

Nickel(Ni)nanoparticles can be enriched on the surface of iron-based frictional pairs,which provides the possibility to get rid of the competitive adsorption between the polar species of vegetable oil and the surface-active nano-additives *** this paper,nickel acetylacetonate was used as a precursor to in-situ synthesize nickel nanoparticles with an average diameter of about 12 nm in rapeseed oil(RO)as the reducing agent,surface modifier,and solvent as *** tribological properties of the as-synthesized Ni nanoparticles were evaluated with a four-ball tribometer,and their tribomechanism was investigated based on the characterizations of the tribofilm on rubbed steel surfaces by the scanning electron microscopy(SEM),transmission electron microscopy(TEM),and X-ray photoelectron spectroscopy(XPS).It was found that the Ni nanoparticles in-situ prepared in the RO with a mass fraction of 0.3%can reduce the wear scar diameter(WSD)of the steel ball by 36%.This is because,on the one hand,the Ni nanoparticles are adsorbed on the rubbed steel surfaces to repair or fill up the micro-pits and grooves *** the other hand,Ni nanoparticles participate in tribochemical reactions with atmospheric O and steel substrate to form the tribochemical reaction film on the rubbed steel surfaces with the assistance of friction-induced heat and applied normal *** addition,an amorphous carbon film is formed on the rubbed surface via the carbonization of base oil under the catalysis of Ni *** adsorbed Ni layer,the tribochemical reaction film,and the carbon layer comprise a composite tribofilm composed of amorphous carbon,polar fatty acid,metallic nickel,iron oxides,and nickel oxides on the rubbed steel surfaces,which contributes to significantly improving the antiwear ability and load-carrying capacity of the RO for the steel-steel sliding pair.

关键词： nickel(Ni)nanoparticles rapeseed oil(RO) in-situ synthesis tribological properties tribomechanism

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Hot spot tracking of f lood remote sensing research over the past 22 years:abibliometric analysis using CiteSpace

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地球环境学报 2024年第4期15卷 612-623页

作者： HUO Hong LIU Yan LI Yang Institute of Desert Meteorology China Meteorological AdministrationUrumqi 830002China Wulanwusu Ecology and Agrometeorology Observation and research Station of Xinjiang Urumqi 830002China Field Scientific Experiment base of Akdala Atmospheric Background China Meteorological AdministrationUrumqi 830002China Meteorological and Technical equipment support Center of Xinjiang Uygur Autonomous Region Xinjiang 830002China

Background,aim,and scope In the context of climate change,extreme precipitation and resulting f looding events are becoming increasingly *** sensing technologies are advantageous for monitoring such disasters due to their wide observation range,periodic revisit capabilities,and continuous spatial *** tools enable real-time and quantitative assessment of f lood *** the past 20 years,the field of remote sensing for f loods has seen significant *** the evolution of research hotspots within this field can offer valuable insights for future research *** and methods This study systematically analyzes the development and hotspot evolution in the field of f lood remote sensing,both domestically and internationally during 2000—*** from CNKI(China National Knowledge Infrastructure)and WOS(Web of Science)databases are utilized for this ***(1)A total of 1693 articles have been published in this field,showing a stable growth trend *** contributors include the Chinese Academy of Sciences,Beijing Normal University,Wuhan University,the Italian National research Council,and National Aeronautics and Space Administration.(2)High-frequency keywords from 2000 to 2021 include“remote sensing”“f lood”“model”“classification”“GIS”“climate change”“area”,and“MODIS”.(3)The most prominent keywords were“GIS”(8.65),“surface water”(7.16),“remote sensing”(7.07),“machine learning”(6.52),and“sentinel-2”(5.86).(4)Thirteen cluster labels were identified through clustering,divided into three phases:2000—2009(initial exploratory stage),2010—2014(period of rapid development),and 2015—2021(steady development of remote sensing for f loods and related disasters).Discussion The field exhibits strong phase-based development,with research focuses shifting over *** 2000 to 2009,emphasis was on remote sensing image application and f lood model *** 2010 to 2014,the focus shifted to accura

关键词： f lood remote sensing CiteSpace review knowledge graph analysis

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A new dynamic pushback control method for reducing fuel-burn costs: Using predicted taxi-out time

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Chinese Journal of Aeronautics 2019年第3期32卷 660-673页

作者： Guan LIAN Yaping ZHANG Zhiwei XING Qian LUO Shaowu CHENG School of Transportation Science and Engineering Harbin Institute of Technology ground support equipment research base Civil Aviation University of China The Second research Institute of Civil Aviation Administration of China

Long departure-taxi-out time leads to significant airport surface congestion, fuel-burn costs, and excessive emissions of greenhouse gases. To reduce these undesirable effects, a Predicted taxi-out time-based Dynamic Pushback Control(PDPC) method is proposed. The implementation of this method requires two steps: first, the taxi-out times for aircraft are predicted by the leastsquares support-vector regression approach of which the parameters are optimized by an introduced improved Firefly algorithm. Then, a dynamic pushback control model equipped with a linear gate-hold penalty function is built, along with a proposed iterative taxiway queue-threshold optimization algorithm for solving the model. A case study with data obtained from Beijing International airport(PEK) is presented. The taxi-out time prediction model achieves predictive accuracy within 3 min and 5 min by 84.71% and 95.66%, respectively. The results of the proposed pushback method show that total operation cost and fuel-burn cost achieve a 14.0% and 21.1%reduction, respectively, as compared to the traditional K-control policy.(3) From the perspective of implementation, using PDPC policy can significantly reduce the queue length in taxiway and taxi-out time. The total operation cost and fuel-burn cost can be curtailed by 37.2% and 52.1%,respectively, as compared to the non-enforcement of any pushback control mechanism. These results show that the proposed pushback control model can reduce fuel-burn costs and airport surface congestion effectively.

关键词： Airport surface operation Fuel-burn cost Gate-hold time Pushback control Taxi-out time prediction Taxiway queue threshold

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A method for active deception jamming discrimination based on frequency response

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Chinese Journal of Aeronautics 2024年第6期37卷 331-347页

作者： Wenbin WEI Ruihui PENG Yunlong DONG Dianxing SUN Le XU Guohong WANG Qingdao Innovation and Development base of Harbin Engineering University Harbin Engineering University150001China Institute of Information Fusion Navy Aeronautical UniversityYantai 264001China

There are many types of radar active deception false target jamming that are highly correlated with the real *** the real and false targets under a low Signal-to-Noise Ratio(SNR)is *** solve the above problem,this article proposes a real/false target recognition method based on the features of multi-pulse joint frequency response by analyzing the differences in the scattering characteristics and modeling real target echoes as a synthesis of multi-scattering center ***,in the range-doppler domain,the real and false targets are truncated along the range dimension,and a fast Fourier transform is performed to extract the features of multi-pulse joint frequency ***,a two-channel feature fusion network is designed for real and false target ***,a Multi-Coherent Processing Interval Joint Decision Method(M-CPIJDM)based on temporal information is proposed to improve the recognition *** using the measured data show that the proposed method can well recognize real and false target signals under four jamming backgrounds:distance false target,velocity false target,distance-velocity composite false target,and forwarding dense false target.

关键词： Activedeception false target jamming Multi-scattering center echo Multi-pulse jointfrequency response feature Two-channelfeature fusion network Multi-coherent processing interval jointdecision

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Recognition of Multifunctional Coded Target in Single-camera Mobile 3D-vision Coordination Measurement

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Semiconductor Photonics and Technology 2009年第3期15卷 167-172页

作者： XU Zhi-hua XIA Ling-li YU Zhi-jing ground support equipment research base of caac Civil Aviation University of China Tianjin 300300 CHN

Single-camera mobile-vision coordinate measurement is one of the primary methods of 3D-coordinate vision measurement, and coded target plays an important role in this system. A multifunctional coded target and its recognition algorithm is developed, which can realize automatic match of feature points, calculation of camera initial exterior orientation and space scale factor constraint in measurement system. The uniqueness and scalability of coding are guaranteed by the rational arrangement of code bits. The recognition of coded targets is realized by cross-ratio invariance restriction, space coordinates transform of feature points based on spacial pose estimation algorithm, recognition of code bits and computation of coding values. The experiment results demonstrate the uniqueness of the coding form and the reliability of recognition.

关键词： coded target mobile vision 3D-coordinates measurement pose estimate match of targets

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Detection and Ranging System of Flight Aid Lights

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Semiconductor Photonics and Technology 2007年第1期13卷 20-24页

作者： YU Zhi-jing WANG Qiang research base of ground support equipment of caac Civil Aviation University of China Tianjin 300300 CHN

Dynamic detection based on optics sensors and ranging radars is a new method to detect the luminous intensity of flight aid lights. The optics sensors can get the illumination information of each light, the ranging radar gets the distance information, and then data amalgamation technology is used to compute the luminous intensity of each light. A method to modify the errors of this dynamic detection system is presented. It avoids the accumulation error and measurement carrier’s excursion error by using peak value detection based on optics sensors to estimate the accurate position of each light, then to modify the lights’ lengthways distance information and transverse position information. The performance of the detection and ranging system is validated by some experiments and shown in pictures.

关键词： luminous intensity dynamic detection illumination optics sensor

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High-efficiency crystalline carbon nitride photocatalysts:Status and perspectives

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Nano research 2024年第9期17卷 7840-7863页

作者： Wenji Pu Yunqiao Zhou Lingfeng Yang Haifeng Gong Yuhan Li Qingyu Yang Dieqing Zhang Engineering research Center for Waste Oil Recovery Technology and equipment Ministry of EducationChongqing Key Laboratory of Catalysis and New Environmental MaterialsChongqing Technology and Business UniversityChongqing 400067China The Education Ministry Key Lab of Resource Chemistry Joint International Research Laboratory of Resource Chemistry of Ministry of EducationShanghai Key Laboratory of Rare Earth Functional Materialsand Shanghai Frontiers Science Center of Biomimetic CatalysisShanghai Normal UniversityShanghai 200234China State Key Laboratory of Tibetan Plateau Earth System Resources and EnvironmentInstitute of Tibetan Plateau ResearchChinese Academy of SciencesBeijing 100101China

Crystallinity and crystal structure greatly influence the photocatalytic behavior of *** g-C3N4 produced by traditional thermal-induced polycondensation reaction bears low crystallinity and thus poor photoactivity,which originates from the incomplete polymerization of the precursor containing amine groups,abundant hydrogen bonds,and unreacted amino,as well as cyanide functional groups in the *** photocatalytic process,these residual functional groups often work as electron trap sites,which may hinder the transfer of electrons on the plane,resulting in low ***,crystalline carbon nitride(CCN)was reported as a promising photocatalyst because its increased crystallinity not only reduces the number of carriers recombination centers,but also increases charge conductivity and improves light utilization due to extendedπ-conjugated systems and delocalizedπ-*** such,we summarize the recent studies on CCN-based photocatalysts for the photoactivity ***,the unique structure and properties of CCN materials are ***,the preparation methods and modification strategies are well *** also sum up the applications of CCN-based materials in the environmental purification and energy ***,this review concerning CNN materials ends with prospects and challenges in the obtainment of high crystallinity by effective techniques,and the deep understanding of photocatalytic mechanism.

关键词： crystalline carbon nitride preparation method modification strategy photocatalytic application

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Promising thermal photonic management materials for sustainable human habitat

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Nano research 2024年第1期17卷 112-131页

作者： Houze Yao Qihua Liao Huhu Cheng Liangti Qu Key Laboratory of Organic Optoelectronics&Molecular Engineering Ministry of EducationDepartment of ChemistryLaboratory of Flexible Electronics TechnologyTsinghua UniversityBeijing 100084China State Key Laboratory of Tribology in Advanced equipment(SKLT) Department of Mechanical EngineeringTsinghua UniversityBeijing 100084China

The spectral characteristics of outdoor structures,such as automobiles,buildings,and clothing,determine their energy interaction with the environment,from broad-spectrum absorption of light energy to high-efficiency thermal *** developed spectrally selective absorption(SSA)materials permit the reduction of energy loss from human habitat eco-system in the sustainable way and further reduce the utilization of fossil energy to achieve carbon *** we review recent advances in SSA materials that enable rational and efficient management of thermal energy and provide new solutions for the resource base that supports human life like comfortable heat management,electricity production,and water *** basic principles of thermal photonic management,the regulation of SSA materials,and functional properties are *** outlook discussing challenges and opportunities in SSA material energy management for comfortable living environments is finally presented,which expects the enormous potential of this interdisciplinary research in solving growing resource-shortage of human society.

关键词： spectrally selective absorption passive cooling solar power eco-system

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Theory and practice of hull dynamic deformation law and heading angle transfer error correction

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Journal of Ocean Engineering and Science 2024年第2期9卷 191-198页

作者： Yepin Qu Jianqiang Liu Yuhai Lyu Chaoran Zhang Tao Li Naval research Institute Shanghai 200436PR China

In order to meet the demand of high-precision heading angle transmission in the transfer alignment of inertial navigation system on moving base,the analytical function relationship between the hull deforma-tion and the turning angular velocity and angular acceleration was derived by using the classical beam theory based on the analysis of the equivalent load exerted by the hydrodynamic force and inertia force on the hull structure during the turning process under the combined action of the steering rudder mo-ment and wave *** objective law between the angular motion and the azimuth deformation angle of the hull under the combined action of maneuvering and sea waves was ***,the correc-tion coefficients were determined according to the left turn and right turn motions of the hull by using the measured data of the ship in the sea trial during the S-shape maneuvering navigation,and the az-imuth deformation angle correction was *** results indicated that the application of the Qu’s bending deformation correction formula could greatly reduce the influence of the hull flexural deforma-tion on the heading angle accuracy,meet the needs of high-precision heading angle transmission,and fully verify the correctness of the hull azimuth deformation law and the heading angle transmission er-ror correction *** theory and method provided technical support for establishing high-precision distributed digital reference in the field of transfer alignment of inertial navigation on moving base and the application of heading angle transfer of other shipborne equipment.

关键词： Hull deformation Hull girder Heading angle Alignment on moving base Transfer alignment Error correction

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The flame retardancy of alginate/flame retardant viscose fibers investigated by vertical burning test and cone calorimeter

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Chinese Chemical Letters 2018年第3期29卷 489-492页

作者： Xian-Sheng Zhang Yan-Zhi Xia Mei-Wu Shi Xiong Yan Key Laboratory of Textile Science & Technology Ministry of Education College of Textiles Donghua University Shanghai 201620 China Laboratory of Fiber Materials and Modern Textile The Growing Base for State Key Laboratory Qingdao University Qingdao 266071 China The Quartermaster equipment research Institute of Logistical support Department Beijing 100082 China

In this research, the flame retardancy of neat alginate fiber, flame retardant viscose fiber （FRV） and alginate/FRV （50/50） blending fibers were investigated by vertical burning and cone calorimeter tests. The vertical burning test showed that the afterflame time of alginate fiber was 0 s, but alginate presented serious smoldering behavior with the afterglow time of 605 s and damaged length of 85 mm, while the afterglow time of FRV was 0 s. When the FRV was incorporated into alginate with the weight ratio of 50/ 50, the afterglow time and damaged length were significantly reduced to 85 s and 35 mm, indicating the smoldering of alginate can be effectively decreased. The morphology and chemical structure of the alginate residual demonstrated that it was seriously destroyed during smoldering process, which was ascribed to its relative low initial thermal degradation temperature. based on the thermal properties analysis, alginate and FRV fibers shared the concurrence of rapid degradation in the same temperature region of 250-300 ℃, through which, the compact and stable char formed by FRV can prevent the heat transmission and suppress the smoldering of alginate. Further, the cone calorimeter results demonstrated that the time to ignition （TTI） significantly increased and peak heat release rate （PHRR） decreased for alginate/FRV （50/50） compared with FRV. With this research, a new method to overcome the smoldering of alginate was proposed by blending with FRV

关键词： Alginate fibers Flame retardant viscose fibers Blending Flame retardancy Vertical burning test Cone calorimeter

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