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Divergent responses of runoff to climate change in the upper basins of the Third Pole dominated by westerlies and monsoon

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Science China Earth Sciences 2024年第8期67卷 2592-2614页

作者： Qikai sun Fengge SU he sun State Key Laboratory of Tibetan Plateau Earth System Environment and Resources(TPESER)Institute of Tibetan Plateau ResearchChinese Academy of SciencesBeijing 100101China University of Chinese Academy of Sciences Beijing 100101China

The diverse climates,distribution of snow and glaciers,and geographic locations directly affect the runoff response to climate change in the upper basins of the Third *** present,a comprehensive analysis of runoff variations and their distinct responses to climate change in the westerlies-and monsoon-dominated upper basins is still *** study comprehensively analyzed annual runoff variations in westerlies-dominated basins(the upper basins of the Aksu(UAKS),Syr Darya(USRD),Yarkant(UYK),Hotan(UHT),Amu Darya(UAMD),and Indus(UI))and monsoon-dominated basins(the upper basins of the Yangtze(UYA),Yellow(UYE),Lancang(ULC),Nujiang(UNJ),and Yarlung Zangbo(UYZ))of the Third Pole from 1961 *** multi-source meteorological data and large-scale circulation factors,this study investigated the divergent responses of runoff in the upper basins to climate change,and explored the large-scale circulation mechanisms underlying runoff variations in these upper *** results showed that:(1)The annual runoff in the majority of upper basins(except for the UYE and UYZ)exhibited an increasing trend,and the annual runoff in the UAKS,UYK,and UI showed a significant increasing trend from1961 to *** annual runoff in the upper basins of the Third Pole changed abruptly from decreasing to increasing between the 1980s and 2000s,with the exception of the UYE.(2)The runoff in the monsoon-dominated upper basins has been controlled primarily by changes in precipitation over the past 55 *** contrast,the runoff in the westerlies-dominated upper basins exhibited three distinct long-term responses to climate change:temperature-dominated(UYK and UHT),precipitation-dominated(USRD and UAMD),and the combined influence of precipitation and temperature(UAKS and UI).Since the 1960s,the sensitivity of runoff to warm season temperature changes in the most westerlies-dominated upper basins has decreased,while the response of runoff to precipitation changes has intensified.(3)The stud

关键词： Upper basins of the Third Pole Climate change Westerlies and monsoon Runoff variations Large-scale circulation factors

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A semi-analytical multi-harmonic balance method on full-3D contact model for dynamic analysis of dry friction systems

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Chinese Journal of Aeronautics 2024年第2期37卷 309-329页

作者： he sun Dayi ZHANG Yaguang WU Qingyang SheN Dianyin HU Research Institute of Aero-Engine Beihang UniversityBeijing 100191China School of Energy and Power Engineering Beihang UniversityBeijing 100191China Beijing Key Laboratory of Aero-Engine Structure and Strength Beijing 100191China Sino-French Engineering School Beihang UniversityBeijing 100191China AECC Sichuan Gas Turbine Research Establishment Chengdu 610500China

Dry friction damping structures are widely-used in aero-engines to mitigate *** nonlinear nature of friction and the two-dimensional in-plane motion on the contact interface bring challenges to accurately and efficiently predict the forced response of frictionally damped *** state-of-the-art Multi-Harmonic Balance Method(MHBM)on quasi-3D contact model in engineering cannot precisely capture the kinematics on the friction interface although the efficiency is *** full-3D contact model can describe the constitutive relationship of the interface in a more accurate manner;however,the efficiency and convergence are not guaranteed for large-scale *** this paper,a semi-analytical MHBM on full-3D contact model is *** original Trajectory Tracking Method(TTM)for evaluating the contact force is reformulated to make the calculation more concise and the derivation of the Analytical Jacobian Matrix(AJM)*** on the chain rule of derivation,the AJM which is the core to upgrade the performance is *** a shrouded blade finite element model,the accuracy and efficiency of the proposed method are compared with both the MHBM on full-3D contact model with numerical Jacobian matrix and the MHBM on quasi-3D contact model with *** results show that the AJM improves significantly the efficiency of the MHBM on full-3D contact *** time cost of the proposed method is in the same order of magnitude as that of the MHBM on quasi-3D contact *** also confirm that the full-3D contact model is necessary for the dynamic analyses of shrouded *** one uses the quasi-3D model,the estimation relative error of damping can even reach 31.8%in some *** addition,the AJM also brings benefits for stability *** is highly recommended that engineers use the MHBM on full-3D contact model for the dynamic analysis and design of shrouded blades.

关键词： Dry friction damping Multi-harmonic balance method Trajectory tracking method Jacobian matrix Shrouded blade

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Increased glacier melt enhances future extreme floods in the southern Tibetan Plateau

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Advances in Climate Change Research 2024年第3期15卷 431-441页

作者： he sun Tan-Dong YAO Feng-Ge SU Tinghai Ou Zhihua he Guoqiang TANG Deliang CheN State Key Laboratory of Tibetan Plateau Earth System Environment and Resources(TPESER)Institute of Tibetan Plateau ResearchChinese Academy of SciencesBeijing 100101China Regional Climate Group Department of Earth SciencesUniversity of GothenburgGothenburg 40530Sweden Centre for Hydrology University of SaskatchewanSaskatoon S7N 1K2Canada Climate and Global Dynamics National Center for Atmospheric ResearchBoulder CO 80307USA

Mountainous areas are of special hydrological concern because topography and atmospheric conditions can result in large and sudden floods,posing serious risks to water-related safety in neighbouring *** Yarlung Zangbo(YZ)River basin is the largest river basin on the Tibetan Plateau(TP),but how floods will discharge in this basin and how the role of glacier melt in floods will change throughout the 21st-century under shared socioeconomic pathways scenarios(SSP2-4.5 and SSP5-8.5)remain ***,we comprehensively address this scientific question based on a well-validated large-scale glacier-hydrology *** results indicate that extreme floods was projected to increase in the YZ basin,and was mainly reflected in increased duration(4–10 d per decade)and intensity(153–985 m^(3)s^(−1)per decade).Glacier runoff was projected to increase(2–30 mm per decade)throughout the 21st-century,but there was also a noticeable decrease or deceleration in glacier runoff growth in the late first half of the century under the SSP2-4.5,and in the latter half of the century under the *** melt was projected to enhance the duration(12%–23%)and intensity(15%–21%)of extreme floods under both SSPs,which would aggravate the impact of future floods on the socioeconomics of the YZ *** effect was gradually overwhelmed by precipitation-induced floods from glacier areas to YZ *** study takes the YZ basin as a projection framework example to help enrich the understanding of future flood hazards in basins affected by rainfall-or meltwater across the TP,and to help policy-makers and water managers develop future plans.

关键词： floods glacier Tibetan

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Dynamically switchable porphyrin-based molecular tweezer for on-off fullerene recognition

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Chinese Chemical Letters 2024年第6期35卷 283-287页

作者： Zhimin sun Xin-Hui Guo Yue Zhao Qing-Yu Meng Li-Juan Xing he-Lue sun College of Chemistry and Materials Science Hebei Key Laboratory of Organic Functional MoleculesHebei Normal UniversityShijiazhuang 050024China

herein,a novel molecular tweezer based on 2,2'-bipyridine-bridged porphyrin subunits was constructed for efficient fullerenes *** syn conformation of the molecule,which was obtained by Zn(Ⅱ)coordination,gives rise to a proper cavity to interact with fullerene guests to form a stable 1:1 complex in toluene *** exhibits distinct binding selectivity towards C_(60)over C_(70).Moreover,the fullerene recognition capacity can be adequately suppressed by importing H_(2)PO_(4)^(-)to competitively capture Zn(Ⅱ)along with syn-anti conformational ***,the molecular tweezer regenerated to bind the fullerene by introducing the Ca^(2+)into the ***,the association-disassociation process can be switched reversibly and repeatedly.

关键词： Molecular tweezer Fullerene recognition Supramolecular chemistry Conformation conversion Coordination

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Study of inter-well interference in shale gas reservoirs by a robust production data analysis method based on deconvolution

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Petroleum Science 2024年第4期21卷 2502-2519页

作者： Wen-Chao Liu Cheng-Cheng Qiao Ping Wang Wen-Song Huang Xiang-Wen Kong Yu-Ping sun he-Dong sun Yue-Peng Jia School of Civil and Resource Engineering University of Science and Technology Beijing PetroChina Research Institute of Petroleum Exploration and Development

In order to overcome the defects that the analysis of multi-well typical curves of shale gas reservoirs is rarely applied to engineering, this study proposes a robust production data analysis method based on deconvolution, which is used for multi-well inter-well interference research. In this study, a multi-well conceptual trilinear seepage model for multi-stage fractured horizontal wells was established, and its Laplace solutions under two different outer boundary conditions were obtained. Then, an improved pressure deconvolution algorithm was used to normalize the scattered production data. Furthermore, the typical curve fitting was carried out using the production data and the seepage model solution. Finally,some reservoir parameters and fracturing parameters were interpreted, and the intensity of inter-well interference was compared. The effectiveness of the method was verified by analyzing the production dynamic data of six shale gas wells in Duvernay area. The results showed that the fitting effect of typical curves was greatly improved due to the mutual restriction between deconvolution calculation parameter debugging and seepage model parameter debugging. Besides, by using the morphological characteristics of the log-log typical curves and the time corresponding to the intersection point of the log-log typical curves of two models under different outer boundary conditions, the strength of the interference between wells on the same well platform was well judged. This work can provide a reference for the optimization of well spacing and hydraulic fracturing measures for shale gas wells.

关键词： Shale gas Inter-well interference Deconvolution Production data analysis Typical curves Multi-stage fractured horizontal well

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Meromorphic Solutions to Higher Order Nonlinear Delay Differential Equations

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Acta Mathematicae Applicatae Sinica 2024年

作者： Ye-zhou LI Ming-yue WU he-qing sun School of Science Beijing University of Posts and Telecommunications Key Laboratory of Mathematics and Information Networks (Beijing University of Posts and Telecommunications) Ministry of Education Beijing University of Posts and Telecommunications

Let w（z） be non-rational meromorphic solutions with hyper-order less than 1 to a family of higher order nonlinear delay differential equations w（z+1）w（z-1）+a（z）w（k）（z）/w（z）=R(z,w（z）),k∈N+,where a（z） is rational,R(z,w（z）)=P(z,w（z）)/Q(z,w（z）) is an irreducible rational function in w with rational coefficients in *** paper mainly show the relationships of the degree of P(z,w（z）) and Q(z,w（z）) when the above equations exist such solutions w（z）.There are also some examples to show that our results are sharp.

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Surface diffraction beamline at the SSRF

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Nuclear Science and Techniques 2024年第7期35卷 47-57页

作者： Yue-Liang Gu Xu Zheng Xing-Min Zhang Bin Zhao Guang-Zhi Yin Da-Ming Zhu Yuan-he sun Xing-Yu Gao Xiao-Long Li Shanghai Advanced Research Institute Chinese Academy of Sciences239 Zhangheng RoadPudong DistrictShanghai201204China

BL02U2 of the Shanghai Synchrotron Radiation Facility is a surface diffraction beamline with a photon flux of 5.5×10^(12) photons/s at 10 keV and a beam size of 160µm×80µm at the sample *** is dedicated to studying surfaces(solid-vacuum,solid-gas)and interfaces(solid-solid,solid-liquid,and liquid-liquid)in nanoscience,condensed matter,and soft matter systems using various surface scattering techniques over an energy range of 4.8-28 keV with transmission and reflection ***,BL02U2 has a high energy resolution,high angular resolution,and low beam divergence,which can provide excellent properties for X-ray diffraction experiments,such as grazing incident X-ray diffraction,X-ray reflectivity,crystal truncation rods,and liquid X-ray *** of in situ environments can also be provided for the samples *** paper describes the setup of the new beamline and its applications in various fields.

关键词： Surface and interface Beamline Surface diffraction Microstructure

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Skyway:Accelerate Graph Applications with a Dual-Path Architecture and Fine-Grained Data Management

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Journal of Computer Science & Technology 2024年第4期39卷 871-894页

作者： Mo Zou Ming-Zhe Zhang Ru-Jia Wang Xian-he sun Xiao-Chun Ye Dong-Rui Fan Zhi-Min Tang Institute of Computing Technology Chinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 100049China Institute of Information Engineering Chinese Academy of SciencesBeijing 100045China Department of Computer Science Illinois Institute of TechnologyChicagoIL 60616U.S.A.

Graph processing is a vital component of many AI and big data ***,due to its poor locality and complex data access patterns,graph processing is also a known performance killer of AI and big data *** this work,we propose to enhance graph processing applications by leveraging fine-grained memory access patterns with a dual-path architecture on top of existing software-based graph *** first identify that memory accesses to the offset,edge,and state array have distinct locality and impact on *** then introduce the Skyway architecture,which consists of two primary components:1)a dedicated direct data path between the core and memory to transfer state array elements efficiently,and 2)a data-type aware fine-grained memory-side row buffer hardware for both the newly designed direct data path and the regular memory hierarchy data *** proposed Skyway architecture is able to improve the overall performance by reducing the memory access interference and improving data access efficiency with a minimal *** evaluate Skyway on a set of diverse algorithms using large real-world *** a simulated fourcore system,Skyway improves the performance by 23%on average over the best-performing graph-specialized hardware optimizations.

关键词： graph application computer architecture memory hierarchy

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Age-of-Information-Aware Federated Learning

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Journal of Computer Science & Technology 2024年第3期39卷 637-653页

作者：徐殷肖明军吴晨吴杰周津锐孙贺 Student Member CCF 1.School of Computer Science and TechnologyUniversity of Science and Technology of ChinaHefei 230026China Suzhou Institute for Advanced Research University of Science and Technology of ChinaSuzhou 215123China School of Data Science University of Science and Technology of ChinaHefei 230026China Department of Computer and Information Sciences Temple UniversityPhiladelphiaPA 19122U.S.A. CCF IEEE

Federated learning(FL)is an emerging privacy-preserving distributed computing paradigm,enabling numerous clients to collaboratively train machine learning models without the necessity of transmitting clients’private datasets to the central *** most existing research where the local datasets of clients are assumed to be unchanged over time throughout the whole FL process,our study addresses such scenarios in this paper where clients’datasets need to be updated periodically,and the server can incentivize clients to employ as fresh as possible datasets for local model *** primary objective is to design a client selection strategy to minimize the loss of the global model for FL loss within a constrained *** this end,we introduce the concept of“Age of Information”(AoI)to quantitatively assess the freshness of local datasets and conduct a theoretical analysis of the convergence bound in our AoI-aware FL *** on the convergence bound,we further formulate our problem as a restless multi-armed bandit(RMAB)***,we relax the RMAB problem and apply the Lagrangian Dual approach to decouple it into multiple ***,we propose a Whittle’s Index Based Client Selection(WICS)algorithm to determine the set of selected *** addition,comprehensive simulations substantiate that the proposed algorithm can effectively reduce training loss and enhance the learning accuracy compared with some state-of-the-art methods.

关键词： federated learning Age of Information restless multi-armed bandit Whittle’s index

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舰艇水下爆炸破损分布特性

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爆炸与冲击 2024年第6期44卷 144-158页

作者：孙赫闫明杜志鹏张磊沈阳工业大学机械工程学院辽宁沈阳110870 海军研究院北京100161

舰艇在作战过程中受到武器攻击,从爆炸产生的破口持续多向进水,影响舰艇的不沉性。为了探究水下爆炸破损分布特性,开展了驳船近场水下爆炸试验,利用声固耦合法计算了冲击波与气泡射流载荷联合作用下全船结构的毁伤,得到整船塑性变形区... 详细信息

舰艇在作战过程中受到武器攻击,从爆炸产生的破口持续多向进水,影响舰艇的不沉性。为了探究水下爆炸破损分布特性,开展了驳船近场水下爆炸试验,利用声固耦合法计算了冲击波与气泡射流载荷联合作用下全船结构的毁伤,得到整船塑性变形区域的凹陷深度为85 cm,L形破口宽30 cm,破口面积为0.2 m2。对比了试验和仿真数据,计算破口尺寸的相对误差小于20%,破口位置吻合较好,验证了模型的准确性。利用该模型进行了不同爆距下爆炸仿真计算,提出了驳船在近场水下爆炸载荷作用下的分布式损伤模式,明确了舰船结构的毁伤除整体折断和局部大型破口外还有广泛分布的小裂缝存在于舱壁、舷侧外板等部位。随着冲击因子从5.74减小至1.91,舱底破口尺寸减小,舱内裂缝增多;当冲击因子在1.91~2.87之间时,舱底破损为分散式的小型破口。舷侧、舱壁与舱底的连接处为薄弱部位,小裂缝分布较多,在舰艇设计过程中可重点加强防护。

关键词：水下爆炸模型试验声固耦合破损分布损伤模式

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