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Spatiotemporal changes in sunshine duration and its influential factors in Chongqing,China from 1961 to 2020

Journal of Mountain Science 2024年第6期21卷 2005-2024页

作者： li Jun XIA Hongxuan JIANG Jinge XU Weifeng WEN Di XU Junfeng College of Geography and Tourism Chongqing Normal UniversityChongqing 401331China Key Laboratory of GIS Application of Chongqing Chongqing 401331China Chongqing Key Laboratory of Earth Surface Processes and Environmental Remote Sensing in Three Gorges Reservoir area Chongqing 401331China Institute of Remote Sensing and Earth Sciences School of Institute of Remote Sensing and Earth SciencesSchool of ScienceHangzhou Normal UniversityHangzhou 311121China

The surface solar radiation in most parts of the world has undergone a phenomenon known as global dimming and brightening,characterized by an initial decrease followed by an *** a result,the sunshine duration(SD)has decreased in the past 60 *** the backdrop of global dimming and brightening,SD has decreased to varying degrees in many regions of *** the observed data of SD,cloud amount(total cloud amount and low cloud amount,abbreviated as TCA and LCA),precipitation,and relative humidity(RH)from 34 meteorological stations in Chongqing during the period of 1961-2020,along with a digital elevation model(DEM)with a resolution of 90 m,this study analyzed the spatiotemporal variations and influencing factors of *** analysis employed methods such as linear regression,Mann-Kendall test,wavelet transformation,and DEM-based possible SD distributed *** results showed that the annual SD in Chongqing has significantly decreased over the last 60 years,with a decreasing interannual trend rate(ITR)of 40.4 h/*** for no obvious trend in spring,SD decreased significantly in summer,autumn and winter at the ITR of 21.1 h/10a,8.5 h/10a and 7.5 h/10a,*** abrupt decrease in the annual SD was found in *** difference before and after the abrupt decrease was 177.7 *** difference before and after the abrupt decrease was 177.7 *** annual SD possessed the oscillation period of *** spatial heterogeneity of the mean annual SD during the last 60 years was *** distribution of SD in Chongqing is high in the northeast and low in the *** addition,about 73%of the total area in Chongqing showed a significant and very significant decreasing *** regions with significant changes are mainly concentrated in the regions with altitudes of 200~1000 *** increasing LCA was the main cause of the decrease of the annual SD in the regions with 200-400 m altitude decreased the most and changed the *** LCA is the prim

关键词： Sunshine duration Spatiotemporal changes Mann-Kendall test Wavelet analysis Geodetector model

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Numerical study on influence of protrusion heights on Reynolds stress and viscous stress variations in turbulent vortical structures

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Chinese Journal of Aeronautics 2024年第9期37卷 59-71页

作者： Zhiping li Long HE Jingsai ZHOU Yueren ZUO Yao YIN Peng ZHANG Bo MENG Research Institute of Aero-Engine Beihang UniversityBeijing 100191China School of Energy and Power Engineering Beihang UniversityBejing 100191China Institute of Acoustics Chinese Academy of SciencesBeijing 100190China College of Aeronautical Engineering Civil Aviation University of ChinaTianjin 300300China AECC Hunan Aviation Powerplant Research Institute Zhuzhou 412002China

Analysing the infuence mechanism of the riblet protrusion height on turbulent drag components is more beneficial in organising the vortical structure over the riblet ***,the Large Eddy Simulation(LES)is used to investigate the vortex structure over the rib-let surface with different protrusion ***,the variations of Reynolds stress and viscous shear stress in a turbulent channel are *** a result,the drag reduction rate increases from 3.4%when the riblets are completely submerged in the turbulent boundary layer to 7.9%when the protrusion height is *** analysis shows that the protrusion height affects the streamwise vortices and the normal diffusivity of spanwise and normal vortices,thus driving the variation of Reynolds *** with the smooth surface,the vorticity strength and the number of streamwise vortices are weakened near the wall but increase in the logarithmic layer with increased protrusion ***,the normal diffusivity of spanwise vorticity decreases with the increase of protrusion height,and the normal diffusivity of normal vorticity is the smallest when the protrusion height is ***,the protrusion height affects the velocity gradient of the riblet tip and riblet valley,thus driving the variation of viscous shear *** the increase of protrusion height,the velocity gradient of the riblet tip increases dramatically but decreases in the riblet valley.

关键词： Riblet Dragreduction Protrusion height Vortical structure Vortexdiffusivity Reynolds stress Viscous stress

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Three‑dimensional numerical simulation of dynamic strength and failure mode of a rock mass with cross joints

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International Journal of Coal Science & Technology 2024年第2期11卷 35-52页

作者： Tingting liu Wenxu Huang Chang Xiang Qian Dong Xinping li Chao Zhang Hubei Key Laboratory of Blasting Engineering Jianghan UniversityWuhan 430056China School of Civil Engineering and Architecture Wuhan University of TechnologyWuhan 430070China Hainan Institute Wuhan University of TechnologySanya 572025China

To study the dynamic mechanical properties and failure characteristics of intersecting jointed rock masses with different joint distributions under confining pressure,considering the cross angleαand joint persistence ratioη,a numerical model of the biaxial Hopkinson bar test system was established using the finite element method–discrete-element model coupling *** validity of the model was verified by comparing and analyzing it in conjunction with laboratory test ***-static combined impact tests were conducted on specimens under various conditions to investigate the strength characteristics and patterns of crack initiation and *** study revealed the predominant factors influencing intersecting joints with different angles and penetrations under impact *** results show that the peak stress of the specimens decreases first and then increases with the increase of the cross ***α<60°,regardless of the value ofη,the dynamic stress of the specimens is controlled by the main ***α≥60°,the peak stress borne by the specimens decreases with increasingη.Whenα<60°,the initiation and propagation of cracks in the cross-jointed specimens are mainly controlled by the main joint,and the final failure surface of the specimens is composed of the main joint and wing ***α≥60°orη≥0.67,the secondary joint guides the expansion of the wing cracks,and multiple failure surfaces composed of main and secondary joints,wing cracks,and co-planar cracks are *** lateral confinement significantly increases the dynamic peak stress able to be borne by the *** triaxial conditions,the degree of failure of the intersecting jointed specimens is much lower than that under uniaxial and biaxial conditions.

关键词： Cross joints Joint distribution form Dynamic failure characteristics FEM–DEM BHPB

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Ni-Catalyzed Enantioselective Difunctionalization of Alkynes to Azepine Derivatives Bearing a Quaternary Center and an Unprotected Imine

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Chinese Journal of Chemistry 2024年第8期42卷 873-878页

作者： Jian Long Zhiwu Lu Xiao-lin li Peng Xue Wen-Bo liu Engineering Research Center of Organosilicon Compounds&Materials(Ministry of Education)and College of Chemistry and Molecular Sciences Wuhan UniversityWuhanHubei430072 China

Comprehensive Summary,The azepine ring is a prominent structural scaffold in biologically significant molecules. In this study, we present a Ni(II)-catalyzed asymmetric difunctionalization of alkynes, involving intermolecular regioselective arylation and intramolecular nitrile addition, enabling the synthesis of enantioenriched azepine derivatives. This reaction simultaneously installs an all-carbon quaternary stereocenter and introduces an unprotected imine functionality, showing great promise for subsequent transformations. The reaction exhibits good tolerance toward various functional groups, resulting in high yields and enantioselectivities. The synthetic utility of this methodology is further demonstrated through gram-scale synthesis and product derivatization. This research offers an efficient approach to the synthesis of seven-membered nitrogen heterocycles.

关键词： Nickel Asymmetric catalysis N-Heterocycles Alkyne functionalization Quaternary centers

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Assessment of Crop Yield in China Simulated by Thirteen Global Gridded Crop Models

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Advances in Atmospheric Sciences 2024年第3期41卷 420-434页

作者： Dezhen YIN Fang li Yaqiong LU Xiaodong ZENG Zhongda liN Yanqing ZHOU International Center for Climate and Environment Sciences Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China University of Chinese Academy of Sciences Beijing 100049China Institute of Mountain Hazards and Environment Chinese Academy of SciencesChengdu 610041China State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China State Key Laboratory of Desert and Oasis Ecology Xinjiang Institute of Ecology and GeographyChinese Academy of SciencesUrumqi 830011China

Global gridded crop models(GGCMs) have been broadly applied to assess the impacts of climate and environmental change and adaptation on agricultural production. China is a major grain producing country, but thus far only a few studies have assessed the performance of GGCMs in China, and these studies mainly focused on the average and interannual variability of national and regional yields. Here, a systematic national-and provincial-scale evaluation of the simulations by13 GGCMs [12 from the GGCM Intercomparison(GGCMI) project, phase 1, and CLM5-crop] of the yields of four crops(wheat, maize, rice, and soybean) in China during 1980–2009 was carried out through comparison with crop yield statistics collected from the National Bureau of Statistics of China. Results showed that GGCMI models generally underestimate the national yield of rice but overestimate it for the other three crops, while CLM5-crop can reproduce the national yields of wheat, maize, and rice well. Most GGCMs struggle to simulate the spatial patterns of crop yields. In terms of temporal variability, GGCMI models generally fail to capture the observed significant increases, but some can skillfully simulate the interannual variability. Conversely, CLM5-crop can represent the increases in wheat, maize, and rice, but works less well in simulating the interannual variability. At least one model can skillfully reproduce the temporal variability of yields in the top-10 producing provinces in China, albeit with a few exceptions. This study, for the first time, provides a complete picture of GGCM performance in China, which is important for GGCM development and understanding the reliability and uncertainty of national-and provincial-scale crop yield prediction in China.

关键词： global gridded crop model historical crop yield China multi-model evaluation

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Identification of transient receptor potential channel genes and functional characterization of TRPA1 in Spodoptera frugiperda

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Journal of Integrative Agriculture 2024年第6期23卷 1994-2005页

作者： Yutong Zhang Hangwei liu Song Cao Bin li Yang liu Guirong Wang State Key Laboratory for Biology of Plant Diseases and Insect Pests Institute of Plant ProtectionChinese Academy of Agricultural SciencesBeijing 100193China Shenzhen Branch Guangdong Laboratory of Lingnan Modern AgricultureGenome Analysis Laboratory of the Ministry of Agriculture and Rural AffairsAgricultural Genomics Institute at ShenzhenChinese Academy of Agricultural SciencesShenzhen 518120China Institute of Evolution and Ecology School of Life SciencesCentral China Normal UniversityWuhan 430079China

Spodoptera frugiperda is a highly destructive pest that has become a global problem due to its robust reproductive and migratory *** receptor potential(TRP)channels,which constitute a vast ion channel family,play pivotal roles in sensing the external environment and maintaining internal homeostasis in *** channels have been widely investigated for their critical roles in regulating various insect behaviors in recent *** this study,we identified 15 TRP gene loci encoding 26 transcripts in the genome of *** and analyzed their expression profiles at different developmental *** results revealed that *** possesses four TRPC genes,six TRPA genes,one TRPM gene,two TRPV genes,one TRPN gene,and one TRPML gene,while a canonical TRPP is ***,the SfruTRPA1 was functionally characterized using the Xenopus oocyte expression *** results showed that SfruTRPA1 is activated by temperature increases from 20 to 45℃,and there is no significant desensitization after repeated stimuli within the same temperature ***,SfruTRPA1 is activated by certain natural chemicals,including allyl isothiocyanate(AITC)and cinnamaldehyde(CA).These findings provide valuable insights to the TRP genes in ***.

关键词： Spodoptera frugiperda transient receptor potential channel expression profile TRPA1 Xenopus oocyte

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Acquiring Weak Annotations for Tumor Localization in Temporal and Volumetric Data

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Machine Intelligence Research 2024年第2期21卷 318-330页

作者： Yu-Cheng Chou Bowen li Deng-Ping Fan Alan Yuille Zongwei Zhou Department of Computer Science Johns Hopkins UniversityBaltimore 21218USA Computer Vision Lab ETH ZurichZurich 8001Switzerland

Creating large-scale and well-annotated datasets to train AI algorithms is crucial for automated tumor detection and ***,with limited resources,it is challenging to determine the best type of annotations when annotating massive amounts of unlabeled *** address this issue,we focus on polyps in colonoscopy videos and pancreatic tumors in abdominal CT scans;Both applications require significant effort and time for pixel-wise annotation due to the high dimensional nature of the data,involving either temporary or spatial *** this paper,we develop a new annotation strategy,termed Drag&Drop,which simplifies the annotation process to drag and *** annotation strategy is more efficient,particularly for temporal and volumetric imaging,than other types of weak annotations,such as per-pixel,bounding boxes,scribbles,ellipses and ***,to exploit our Drag&Drop annotations,we develop a novel weakly supervised learning method based on the watershed *** results show that our method achieves better detection and localization performance than alternative weak annotations and,more importantly,achieves similar performance to that trained on detailed per-pixel ***,we find that,with limited resources,allocating weak annotations from a diverse patient population can foster models more robust to unseen images than allocating per-pixel annotations for a small set of *** summary,this research proposes an efficient annotation strategy for tumor detection and localization that is less accurate than per-pixel annotations but useful for creating large-scale datasets for screening tumors in various medical modalities.

关键词： Weak annotation detection localization segmentation colonoscopy abdomen

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Rice canopy temperature is affected by nitrogen fertilizer

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Journal of Integrative Agriculture 2024年第3期23卷 824-835页

作者： Min Jiang Zhang Chen Yuan li Xiaomin Huang lifen Huang Zhongyang Huo Jiangsu Key Laboratory of Crop Genetics and Physiology/Jiangsu Key Laboratory of Crop Cultivation and Physiology/Agricultural College Yangzhou UniversityYangzhou 225009China Jiangsu Co-lnnovation Center for Modern Production Technology of Grain Crops Yangzhou UniversityYangzhou 225009China

Canopy temperature strongly influences crop yield formation and is closely related to plant physiological ***, the effects of nitrogen treatment on canopy temperature and rice growth have yet to be comprehensively examined. We conducted a two-year field experiment with three rice varieties(HD-5, NJ-9108, and YJ-805) and three nitrogen treatments(zero-N control(CK), 200 kg ha~(–1)(MN), and 300 kg ha~(–1)(HN)). We measured canopy temperature using a drone equipped with a high-precision camera at the six stages of the growth period. Generally,canopy temperature was significantly higher for CK than for MN and HN during the tillering, jointing, booting, and heading stages. The temperature was not significantly different among the nitrogen treatments between the milky and waxy stages. The canopy temperature of different rice varieties was found to follow the order: HD-5>NJ-9108>YJ-805, but the difference was not significant. The canopy temperature of rice was mainly related to plant traits, such as shoot fresh weight(correlation coefficient r=–0.895), plant water content(–0.912), net photosynthesis(–0.84), stomatal conductance(–0.91), transpiration rate(–0.90), and leaf stomatal area(–0.83). A structural equation model(SEM) showed that nitrogen fertilizer was an important factor affecting the rice canopy *** study revealed:(1) A suite of plant traits was associated with the nitrogen effects on canopy temperature,(2) the heading stage was the best time to observe rice canopy temperature, and(3) at that stage, canopy temperature was negatively correlated with rice yield, panicle number, and grain number per panicle. This study suggests that canopy temperature can be a convenient and accurate indicator of rice growth and yield prediction.

关键词： canopy temperature rice physiological and biochemical characteristics yield

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Functional microfluidics:theory,microfabrication,and applications

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International Journal of Extreme Manufacturing 2024年第3期6卷 140-173页

作者： Mingzhu Xie Ziheng Zhan Yinfeng li Junkai Zhao Ce Zhang Zhaolong Wang Zuankai Wang Interdisciplinary Research Center of Low-carbon Technology and Equipment College of Mechanical and Vehicle EngineeringHunan UniversityChangsha 410082People’s Republic of China Energy Research Institute of Shandong Academy of Sciences Qilu University of Technology(Shandong Academy of Sciences)Jinan 250014People’s Republic of China Qian Xuesen Laboratory of Space Technology China Academy of Space Technology(CAST)Beijing 100094People’s Republic of China Department of Mechanical Engineering Hong Kong Polytechnic UniversityHong Kong Special Administrative Region of China 999077People’s Republic of China

Microfluidic devices are composed of microchannels with a diameter ranging from ten to a few hundred ***,quite a small(10-9–10-18l)amount of liquid can be manipulated by such a precise *** the past three decades,significant progress in materials science,microfabrication,and various applications has boosted the development of promising functional microfluidic *** this review,the recent progress on novel microfluidic devices with various functions and applications is ***,the theory and numerical methods for studying the performance of microfluidic devices are briefly ***,materials and fabrication methods of functional microfluidic devices are ***,the recent significant advances in applications of microfluidic devices are highlighted,including heat sinks,clean water production,chemical reactions,sensors,biomedicine,capillaric circuits,wearable electronic devices,and ***,perspectives on the challenges and future developments of functional microfluidic devices are *** review aims to inspire researchers from various fields engineering,materials,chemistry,mathematics,physics,and more—to collaborate and drive forward the development and applications of functional microfluidic devices,specifically for achieving carbon neutrality.

关键词： capillary theory functional devices functional microfluidics

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Analysis of impact pressure,rock-breaking effect,and ground vibration induced by the disposable CO_(2)fracturing tube

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第8期16卷 3099-3121页

作者： Chong Yu Yongan Ma Haibo li Shouchun Deng Yafei Hao Kuan Zhu State Key Laboratory of Geomechanics and Geotechnical Engineering Institute of Rock and Soil MechanicsChinese Academy of SciencesWuhan430071China University of Chinese Academy of Sciences Beijing100049China Explosives Co.Ltd. Changsha410000China Wuhan University of Science and Technology Wuhan430000China Gezhouba EXPL(Hunan)Technology Co.Ltd. Liuyang410300China

The technology of expansion fracturing with liquid CO_(2)(EFLCO_(2))has attracted increasing attention due to reduced vibration and *** disposable fracturing tube has been developed and is gradually replacing the Cardox ***,there is a lack of impact pressure testing of disposable tubes under real working conditions,selection of gas explosion design parameters,and systematic analysis of blasting *** limitation has constrained the widespread application of disposable fracturing tubes in engineering.A joint monitoring of the pressure-time curves in the disposable tubes and boreholes was *** rock-breaking effect of varying hole spacing parameters in the EFLCO_(2)design was analyzed,and a systematic study was carried out on the vibration peak value,frequency,and energy *** results show that(1)the pressure distribution characteristics,stress peak value,and duration in the disposable tubes are different from those of Cardox tubes,which show multi-peak distribution,low-pressure peak value,and short *** correlation between the pressure in the disposable tube,filling pressure,and liquid CO_(2)weight is established,and a theoretical calculation method for the borehole wall pressure is proposed;(2)The hole spacing in rocks of different hardness is suggested;and(3)At the same scale distance,the peak particle velocity(PPV)caused by EFLCO_(2)(PPVCO_(2))is significantly smaller than that caused by blasting(PPVexplosive).The ratio of PPVexplosive to PPVCO_(2)is a power function related to scale distance,and a distance-related zonality exist in this *** frequency composition of the vibration signal caused by EFLCO_(2)is relatively simple with a narrow frequency *** PPV and energy are mainly concentrated in the low-frequency *** research contributes to the optimization of disposable fracturing tubes,gas explosion design,and vibration hazard control.

关键词： Disposable tube liquid CO_(2) Impact pressure Hole spacing Vibration effect Cardox tube

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