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Extreme precipitation detection ability of four high-resolution precipitation product datasets in hilly area:a case study in Nepal

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Advances in Climate Change Research 2024年第3期15卷 390-405页

作者： Sunil Subba Yao-Ming ma Wei-Qiang ma Cun-Bo Han Land-Atmosphere Interaction and its Climatic Effects Group State Key Laboratory of Tibetan Plateau Earth SystemEnvironment and Resources(TPESER)Institute of Tibetan Plateau ResearchChinese Academy of SciencesBeijing 100101China College of Earth and Planetary Sciences University of Chinese Academy of SciencesBeijing 100049China College of Atmospheric Science Lanzhou UniversityLanzhou 730000China National Observation and Research Station for Qomolongma Special Atmospheric Processes and Environmental Changes Dingri 858200China Kathmandu Center of Research and Education Chinese Academy of SciencesBeijing 100101China China-Pakistan Joint Research Center on Earth Sciences Chinese Academy of SciencesIslamabad 45320Pakista

Given Nepal's vulnerability to extreme precipitation(EP),it is imperative to conduct a comprehensive analysis to comprehend the historical trends of such ***,acquiring precise precipitation data for EP remains challenging in mountainous countries like Nepal owing to the scarcity of densely gauged *** limitation impedes the dissemination of knowledge pertaining to EP variability events in *** current research on this topic is deficient for two main reasons:1)there is a lack of studies leveraging recently released high-resolution precipitation products to identify their EP detection capabilities,which further hinders the usability of those products in data-scarce regions like Nepal,and 2)most studies have focused on the characterisation of EP events in Nepal rather than their spatial and temporal *** address these issues,this study evaluated the EP detection capabilities of four high-resolution precipitation product datasets(PPDs)across Nepal from 1985 to *** datasets include the ERA5 Land reanalysis data,satellite-based precipitation data(PERSIANN_CCS_CDR and CHIRPS_V2.0)and a merged dataset(TPHiPr).We used various statistical and categorical indices to assess their ability to capture the spatial and temporal variability of EP *** annual EP events were characterised by 11 indices divided into frequency and intensity *** TPHiPr merged dataset offered a robust depiction of monthly precipitation estimates,achieving the highest critical success index,accuracy,probability of detection and a low false alarm ratio for daily precipitation detection of 0.1 mm in ***,the PERSIANN_CCS_CDR dataset exhibited poor *** PPDs showed increasing trends in EP ***,the TPHiPr dataset showcased those trends with fewer errors and stronger correlations for many frequency(R10mm,R20mm and R25mm)and intensity(RX1day,RX5day,PRCPTOT and R99p)*** results indicate that TPHiPr outperformed ot

关键词： Extreme precipitation Precipitation product Nepal TPHiPr ERA5 land PERSIANN_CCS_CDR CHIRPS_V2.0

Take Every Step Firmly with Sharp Eyes

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Chinese Journal of Chemistry 2024年第10期42卷 1065-1066页

作者： Shengming ma Chinese Journal of Chemistry

Chinese Journal of Chemistry(CJC)is committed to becoming a prominent international journal for chemistry and the related *** are working very hard towards this *** offers a diverse range of manuscript types,including... 详细信息

关键词： journal becoming diverse

Impact of Polymer matrix on Polymer Mechanochromism from Excited State Intramolecular Proton Transfer

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Chinese Journal of Chemistry 2024年第6期42卷 611-616页

作者： Yu Wu Xin Cheng Huan Hu Shui Hu Zhimin ma Zhiyong ma Beijing Advanced Innovation Center for Soft matter Science and Engineering Beijing State Key Laboratory of Organic-Inorganic CompositesCollege of Chemical EngineeringBeijing University of Chemical TechnologyBeijing100029 China Center of Advanced Elastomer materials College of Materials Science and EngineeringBeijing University of Chemical TechnologyBeijing100029 China College of Engineering Peking UniversityBeijing100871 China

Mechanochromic polymers based on non-covalent changes have attracted much attention ***,we report the impact of inter/intramolecular hydrogen bonds on polymer mechanochromism from the excited state intramolecular proton transfer (ESIPT) ***-NH2-OH and PhMz=2A are designed and obtained by simple and high-yield synthesis,and are connected into polyurethane and poly(methyl acrylate-co-2-ethylhexyl acrylate),*** the initial state,the PhMz-NH2-OH@PU sample shows blue fluorescence from the excited enol form (E*) excitons,owing to intermolecular hydrogen bonds that interrupt the ESIPT reactions but the PhMz=2A@Pma-2-EA sample expresses cyan fluorescence belonging to the excited keto form (K*) emission,implying that the intramolecular hydrogen bonds ***,under stretching,external force can tune the emission of the PhMz=2A@Pma-2-EA sample from K* to E* *** external force can putatively still promote a bond rotation,ESIPT reactions remain equivalently interrupted in both the relaxed and stressed states in a hydrogen-bond donating *** calculation confirms the force-induced increase in dihedral angle for the transition of ESIPT-on/***,PhMz-NH2-OH@PU and PhMz=2A@Pma-2-EA showed disparate initial ESIPT states and further different responses/sensitivity to *** study reports a novel and efficient strategy for enriching mechanochromic investigation and extending the applications of ESIPT reactions.

关键词： Polymer mechanochromism Excited state intramolecular proton transfer Hydrogen bonding Supramolecular chemistry Elastomers

A rigorous real-time acoustic positioning method for ocean bottom seismic exploration

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Satellite Navigation 2024年第1期5卷 168-190页

作者： Jinye ma Shouchuan Fang Jianhu Zhao School of Geodesy and Geomatics Wuhan University129 Luoyu RoadWuhan430079China Institute of marine Science and Technology Wuhan UniversityWuhan430079China Surveying Service Center BGP Inc.CNPCZhuozhou072751HebeiChina

The conventional technique for positioning seafloor geophones in ocean bottom seismic exploration encounters several challenges,including the significant impact of outliers on positioning results,underutilization of high-precision observations,and low efficiency in real-time data *** issues inevitably affect the quality of seismic exploration *** address these challenges and enhance the accuracy of geophone positioning,this paper proposes a rigorous real-time acoustic positioning method for geophones based on sequential adjustment and Baarda's outlier detection *** proposed method comprises three key steps:grouping the original acoustic observations,constructing the intra-group acoustic positioning model,and synthesizing the positioning results across the different *** validity and practicality of this approach are confirmed through a simulation experiment as well as the field experiment conducted in the Bohai Sea,*** results demonstrate that the proposed method effectively eliminates outliers in the original observations and maximizes the utilization of high-quality *** to traditional acoustic positioning methods,it significantly reduces positioning errors from meters to decimeters,and in some cases can achieve centimeter-level *** the sound velocity profile in the operating sea area is measured,the method can attain the posterior standard deviation at the millimeter level and positioning errors within 10 *** the sound velocity profile is unknown,the method can achieve the posterior standard deviation at centimeter-level and positioning errors of approximately 20 cm.

关键词： Ocean bottom seismic exploration Geophone positioning Acoustic positioning method Sequential adjustment Outlier detection

Bionic soft robotic gripper with feedback control for adaptive grasping and capturing applications

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Frontiers of Mechanical Engineering 2024年第1期19卷 129-148页

作者： Tingke WU Zhuyong LIU Ziqi ma Boyang WANG Daolin ma Hexi YU Department of Engineering Mechanics School of Ocean and Civil EngineeringShanghai Jiao Tong UniversityShanghai 200240China State Key Laboratory of Ocean Engineering Shanghai Jiao Tong UniversityShanghai 200240China MOE Key Laboratory of Hydrodynamics Shanghai Jiao Tong UniversityShanghai 200240China

Robots are playing an increasingly important role in engineering *** robots have promising applications in several fields due to their inherent advantages of compliance,low density,and soft interactions.A soft gripper based on bio-inspiration is proposed in this *** analyze the cushioning and energy absorption mechanism of human fingertips in detail and provide insights for designing a soft gripper with a variable stiffness *** investigate the grasping modes through a large deformation modeling approach,which is verified through *** characteristics of the three grasping modes are quantified through testing and can provide guidance for robotics ***,the adaptability of the soft gripper is verified by grasping multi-scale and extremely soft ***,a cushioning model of the soft gripper is proposed,and the effectiveness of cushioning is verified by grasping extremely sharp objects and living ***,we validate the advantages of the variable stiffness of the soft gripper,and the results show that the soft robot can robustly complete assemblies with a gap of only 0.1 *** to the unstructured nature of the engineering environment,the soft gripper can be applied in complex environments based on the abovementioned experimental ***,we design the soft robotics system with feedback capture based on the inspiration of human catching *** feasibility of engineering applications is initially verified through fast capture experiments on moving *** design concept of this robot can provide new insights for bionic machinery.

关键词： soft bionic gripper variable stiffness structure large deformation modeling feedback control soft robotic system

Tuning Surface Molecular Design of Porous Carbon for Blue Energy Harvesting

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Research 2024年第1期2023卷 651-662页

作者： Jian Yu Zhong-Lin Wang Tianwei ma Department of Civil and Environmental Engineering University of Hawaii at MānoaHonoluluHI 96822USA Beijing Institute of Nanoenergy and Nanosystems Chinese Academy of SciencesBeijing 101400China College of Engineering Texas A&M University-Corpus ChristiCorpus ChristiTX 78412USA

Capacitive mixing is a promising blue energy technology due to its membrane-free electricity generation and long electrode life ***,because of limited performance,existing systems do not lend themselves to practical *** it is a crucial factor directly influencing electrode behavior,surface chemistry has largely been overlooked in capacitive ***,we show that manipulating surface functionalization alone can tune the responses of electrodes to produce a high voltage rise without altering the pore structure of the *** findings reveal that the spontaneous electrode potential of a surface-modified carbon electrode shifts negatively proportional to the surface charge due to the surface groups,which explains why and how manipulating the surface chemistry can improve the power generation capacity.

关键词： electrode Porous mixing

Deployment analysis of composite thin-walled lenticular tubes with effect of storage time and temperature

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Chinese Journal of Aeronautics 2024年第1期37卷 162-172页

作者： Jinfeng DENG Ning AN Qilong JIA Xiaofei ma School of Aeronautics and Astronautics Sichuan UniversityChengdu 610065China State Key Laboratory for Strength and Vibration of Mechanical Structures School of AerospaceXi’an Jiaotong UniversityXi’an 710049China State Key Laboratory of Structural Analysis for Industrial Equipment Dalian University of TechnologyDalian 116024China Xi’an Institute of Space Radio Technology Xi’an 710100China

Composite Thin-walled Lenticular Tube(CTLT)is increasingly utilized in small satellites missions as a lightweight,foldable,and rollable structural material that facilitates the construction of large deployable *** CTLT is initially flattened and coiled around a central hub for storage before launch,during which elastic energy is stored as deformation energy,allowing it to be self-deployed on demand for use in *** work presents a comprehensive investigation into the coiling,storage and deployment behaviors of CTLT that wraps around a central hub.A nonlinear explicit dynamic finite element model was developed with both deformable CTLT and rigidbodies mechanisms including the central hub and guide rollers,as well as the complex interactions among *** coiling mechanics characteristics such as stored strain energy and rotational moment were presented and validated against experimental data in the ***,the dynamic deployment behaviors were analyzed in terms of two different deployment methods,namely,controlled deployment and free *** effect of material property change during storage was also discussed through numerical experiments.

关键词： Composite deployable structures Deployment dynamics Finite element method Stress relaxation Thin-walled booms

维普期刊数据库

Capturing metal clusters at the strong-interaction region to reverse Ostwald ripening

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Science China materials 2024年第4期67卷 1363-1364页

作者： Shuheng Tian Ding ma Beijing National Laboratory for Molecular Sciences New Cornerstone Science LaboratoryCollege of Chemistry and Molecular EngineeringPeking UniversityBeijing 100871China

High-temperature interactions induce sintering of metal nanoparticles(NPs) on heterogeneous catalyst surfaces, leading to reduced surface area and active site loss through Ostwald ripening [1]. This irreversible deactivation necessitates costly catalyst replacement, notably impacting metals like copper in hydrogenation and reforming reactions [2].

关键词： catalyst reforming irreversible

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Two-stage aging treatment to accelerate aging kinetics without impairing strength in B4C/7A04Al composite

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Science China Technological Sciences 2024年第8期67卷 2485-2492页

作者： CHEN YunTao ma GuoNan ZHU ShiZe WANG Dong XIAO BoLv ma ZongYi Shi-Changxu Innovation Center for Advanced materials Institute of Metal Research Chinese Academy of Sciences School of materials Science and Engineering University of Science and Technology of China Centre of Excellence for Advanced materials

Aging treatments are the key process to obtain satisfactory strength for 7xxxAl alloys and their composites. However, traditional single-stage（SS） aging is time-consuming to reach a peak strength condition. In this study, an efficient 120℃ + 160℃ two-stage（TS） aging treatment was proposed on a B4C/7A04Al composite fabricated via powder metallurgy（PM） technology, which could acquire similar peak-aging strength but only took about 15% of the time compared to traditional 120℃ SS aging. The evolution of precipitation during the TS aging was investigated, as well as those of the 7A04Al alloys for comparison. In the second stage aging process, the higher aging temperature accelerated the nucleation of η′ phases inside the grains and thus increased the density of precipitates. Moreover, the short aging time limited the coarsening of precipitates and the broadening of precipitatefree zones. The above factors were beneficial for quickly obtaining satisfactory precipitation strengthening effects. The B4C/7A04Al composite exhibited slower aging kinetics than the 7A04Al alloy in the TS aging. Mg elements consumption by the chemical reaction between B impurities introduced by B4C particles and the Al matrix was considered to potentially retard the aging kinetics of the B4C/7A04Al composite. Nevertheless, the precipitation sequence was not affected.

关键词： aluminum matrix composites aging treatment powder metallurgy mechanical properties precipitation