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Research progress of slippage characteristic and gas film stability enhancement methods on biomimetic hydrophobic surfaces

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Journal of Hydrodynamics 2024年第1期36卷 87-101页

作者： Meng-zhuo Zhang Hai-bao Hu Liu-zhen Ren Lu-yao bao Jun Wen Luo Xie School of Marine Science and Technology Northwestern Polytechnical UniversityXi’an710072China Research and Development Institute of Northwestern Polytechnical University in Shenzhen Shenzhen518063China

The biomimetic hydrophobic surface is a potentially efficient underwater drag reduction method and the drag reduction mechanism of this kind of surface comes from the interfacial *** now,it is a hotspot to grasp the slippage characteristic and explore slippage enhancement *** paper not only summarizes our numerical simulation and experimental results of slippage characteristic at the solid-liquid interface(SLI)of hydrophobic surfaces(HS)and the gas-liquid interface(GLI)of superhydrophobic surfaces(SHS)in recent years,but also introduces some innovative methods that can effectively improve the gas film stability and drag reduction effect of ***,we used the molecular dynamics(MD)simulation method to figure out the effect of the solid-liquid interaction strength,the system temperature and the shear rate on the slippage of SLI,and expound their action mechanism from molecular ***,by MD and multibody dissipative particle dynamics(MDPD)method,the slippage behavior at the GLI was studied under the influence of the microstructure size and the flow driving *** proposed a new kind of hybrid slip boundary condition model to describe the slippage characteristic on *** addition,we found through experiment that a three-dimensional backflow will appear on the GLI under the interfacial adsorption of surfactants,and the backflow direction will reverse with the change of GLI ***,we put forward the wettability step structure and gas injection method to enhance the stability and drag reduction effect of the gas film on SHS.

关键词： Hydrophobic surface superhydrophobic surface interfacial slip underwater drag reduction

2022汤加海底火山活动的测高海面观测异常分析

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测绘学报 2024年第2期53卷 263-273页

作者：李倩倩鲍李峰王勇中国科学院精密测量科学与技术创新研究院大地测量与地球动力学国家重点实验室湖北武汉430077 中国科学院大学北京100049

2022年1月14日—2022年1月15日,汤加海底火山发生剧烈喷发并造成全球性海啸,引起了国际广泛关注。针对汤加火山喷发引起的海洋环境异常综合观测,本文提出了利用Jason-3测高卫星数据研究火山喷发对海洋环境的短期和长期影响。针对短期影... 详细信息

2022年1月14日—2022年1月15日,汤加海底火山发生剧烈喷发并造成全球性海啸,引起了国际广泛关注。针对汤加火山喷发引起的海洋环境异常综合观测,本文提出了利用Jason-3测高卫星数据研究火山喷发对海洋环境的短期和长期影响。针对短期影响,利用距离火山最近的弧段186的重复轨道,对比不同时间观测值,分析火山喷发时期海平面变化、有效波高和电离层总电子含量(TEC)异常。结果表明:卫星测高可观测到火山喷发引起的海面异常。火山喷发期间:海平面产生短期变化,原因可能与火山活动引起的波浪、海洋环境变化和海底地形变化有关;火山喷发引起部分海域有效波高显著增加,弧段186区域电离层TEC明显降低。针对长期影响,构建了研究区域内2016年2月—2023年2月共7年区域平均海面观测时间序列,并采用小波变换、奇异谱分析方法探测时间序列中的异常扰动,分析其与火山活动的关系,从而推断火山喷发活动对海洋环境的长期影响。结果表明:火山喷发可能会对海平面变化产生长期影响,海平面变化分布与俯冲带位置相关,其影响还与EI Nino和La Nina事件产生的影响耦合,需要更多资料进一步分析;另外,汤加火山喷发对研究海域内的平均有效波高和电离层TEC分布长期影响较小。

关键词：汤加火山卫星测高海平面变化电离层异常有效波高

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Barrier Option Pricing in Regime Switching Models with Rebates

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Acta Mathematicae Applicatae Sinica 2024年第3期40卷 849-861页

作者： Yue-xu ZHAO Jia-yong bao School of Economics Hangzhou Dianzi UniversityHangzhou 310018China School of Sciences Hangzhou Dianzi UniversityHangzhou 310018China

This paper is concerned with the valuation of single and double barrier knock-out call options in a Markovian regime switching model with specific *** integral formulas of the rebates are derived via matrix Wiener-Hopf factorizations and Fourier transform techniques,also,the integral representations of the option prices are ***,the first-passage time density functions in two-state regime model are *** applications,several numerical algorithms and numerical examples are presented.

关键词： option pricing Markovian regime switching Wiener-Hopf factorization Fourier transform

Testing Linearity in Functional Partially Linear Models

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Acta Mathematicae Applicatae Sinica 2024年第3期40卷 875-886页

作者： Fan-rong ZHAO bao-xue ZHANG School of Mathematical Sciences Shanxi UniversityTaiyuan 030006China School of Statistics Capital University of Economics and BusinessBeijing 100070China

For the functional partially linear models including flexible nonparametric part and functional linear part,the estimators of the nonlinear function and the slope function have been studied in existing *** to test the correlation between response and explanatory variables,however,still seems to be ***,a test procedure for testing the linearity in the functional partially linear models will be proposed in this paper.A test statistic is constructed based on the existing estimators of the nonlinear and the slope ***,we prove that the approximately asymptotic distribution of the proposed statistic is a chi-squared distribution under some regularity ***,some simulation studies and a real data application are presented to demonstrate the performance of the proposed test statistic.

关键词： asymptotic theory functional partially linear model Nadaraya-Watson estimate test statistic

Spatiotemporal patterns and drivers of cultivated land conversion in Inner Mongolia Autonomous Region,northern China

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Journal of Arid Land 2024年第9期16卷 1197-1213页

作者： Xijiri ZHOU Ruiping bao baorong Burenjirigala College of Geographical Science Inner Mongolia Normal UniversityHohhot 010022China Dongsheng District Sub-bureau of Ordos Natural Resources Bureau Ordos 017000China Chifeng University Chifeng 024000China

Protection and optimization of cultivated land resources are of great significance to national food *** land conversion in northern China has increased in recent years due to the industrialization and urbanization of ***,the assessment of cultivated land conversion in this area is insufficient,posing a potential risk to cultivated land *** study evaluated the evolution and spatiotemporal patterns of cultivated land conversion in Inner Mongolia Autonomous Region,China,and the driving factors to improve rational utilization and to protect cultivated land *** spatiotemporal patterns of cultivated land conversion in Inner Mongolia were analyzed using the cultivated land conversion index,kernel density analysis,a standard deviation ellipse model,and a geographic *** showed that from 2000 to 2020,the trends in cultivated land conversion area and rate in Inner Mongolia exhibited fluctuating growth,with the total area of cultivated land conversion reaching 7307.59 km^(2) at a rate of 6.69%.Spatial distribution of cultivated land conversion was primarily concentrated in the Hetao Plain,Nengjiang Plain,Liaohe Plain,and the Hohhot-baotou-Ordos urban ***,the standard deviational ellipse of cultivated land conversion in Inner Mongolia exhibited a directional southwest-northeast-southwest-northeast distribution,with the northeast-southwest direction identified as the main driving force of spatial change in cultivated land ***,cultivated land conversion exhibited an increase-decrease-increase change process,indicating that spatial distribution of cultivated land conversion in Inner Mongolia became gradually apparent within the study *** geographic detector results further revealed that the main driving factors of cultivated land conversion in Inner Mongolia were the share of secondary and tertiary industries and per-unit area yield of grain,with explanatory rates of 57.00%,55.0

关键词： cultivated land conversion spatiotemporal variation standard deviation elliptical models geographic detector northern China

Unveiling oscillatory nature for sustainable fuel production

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National Science Review 2024年第5期11卷 90-91页

作者： Ning Han Ye Wang bao-Lian Su Department of Materials Engineering State Key Laboratory of Physical Chemistry of Solid Surfaces Collaborative Innovation Center of Chemistry for Energy Materials National Engineering Laboratory for Green Chemical Productions of Alcohols Ethers and Esters College of Chemistry and Chemical Engineering Xiamen University Laboratory of Inorganic Materials Chemistry(CMI) University of Namur State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology

A century ago, in 1923, Franz Fischer and Hans Tropsch introduced the groundbreaking Fischer–Tropsch (FT) synthesis, a heterogeneous catalytic process used to convert synthesis gas (syngas,CO+H2) into multi-carbon hydrocarbons [1]. Over the past 100 years, FT synthesis has emerged as a pivotal method for converting non-petroleum resources into exceptionally clean fuels or valuable chemicals via syngas [2–4].

关键词： CO HYDROGENATION CATALYSTS BEHAVIOR KINETICS

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多元智能理论对青少年宫兴趣培训项目的启示

青少年研究与实践 2015年第1期30卷 57-60页

作者：鲍倩倩浙江省团校浙江杭州310012

随着社会对素质教育越来越高的要求、家长对孩子全面发展越来越高的期望、学校教育在素质教育转型中的努力突破、各种社会培训机构风生水起的激烈竞争,青少年宫的兴趣培训亟须探索出一条既不同于学校应试教育,又不同于培训机构的可持续... 详细信息

随着社会对素质教育越来越高的要求、家长对孩子全面发展越来越高的期望、学校教育在素质教育转型中的努力突破、各种社会培训机构风生水起的激烈竞争,青少年宫的兴趣培训亟须探索出一条既不同于学校应试教育,又不同于培训机构的可持续发展之路。美国哈佛大学心理学教授霍华德·加德纳提出了多元智能理论,为青少年宫的个性化兴趣培训带来了启示,青少年宫一线教师以多元智能理论为指导,创设活泼新颖的教学方法、多元实用的测试游戏、全面科学的学员评估方式,从而推动了校外兴趣培训项目的转型发展。

关键词：多元智能理论青少年宫兴趣培训启示

Forced boiling of nonazeotropic immiscible mixture in a supercapillary microchannel array for ultra-high heat flux removal with chip junction temperature below 85℃

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Science China(Technological Sciences) 2024年第5期67卷 1364-1380页

作者： SUN Bo bao YuChen TIAN Tong LI Ji School of Engineering Science University of Chinese Academy of SciencesBeijing100049China Laboratory of Advanced Thermal Management Technologies School of Engineering ScienceUniversity of Chinese Academy of SciencesBeijing100049China

In this study,a structure-optimized two-phase microchannel heat sink with sintered submicron nucleation sites was developed and *** copper-based microchannels had a rectangular cross-section with an equivalent hydraulic diameter of 222μ*** subcooled flow boiling characteristics were comprehensively compared between pure HFE-7100 and a non-azeotropic,immiscible binary mixture of HFE-7100 and water,considering heating areas of 1 and 5 cm^(2).The total heating power input to the test section were 100–1500 and 250–3000 W for a 1 and 5 cm^(2)heat source,respectively,with a flow rate ranging from 50 to150 L/*** to pure HFE-7100,the non-azeotropic immiscible binary mixture of HFE-7100/water in the sintered porous microchannels exhibited a much higher overall heat transfer coefficient and lower power *** maintain the junction temperature of a high power electronic chip below 85℃,the proposed supercapillary microchannel heat sink could effectively dissipate the heat flux of 1275 W/cm^(2)over 1 cm^(2)heat source and 500 W/cm^(2)over 5 cm^(2)heat *** addition,the volume ratio of the binary mixture strongly influence the two-phase flow heat transfer *** optimal volume ratio exist in terms of the thermal resistance–pumping power minimization(HFE-7100:water=2:8 is recommended in this study).The findings of this investigation on the flow boiling properties of non-azeotropic immiscible mixtures help fill a gap in the related field.

关键词： microchannel sintered powder coating submicron nucleation cavities nonazeotropic immiscible ultra-high heat flux

A Modified Iterative Learning Control Approach for the Active Suppression of Rotor Vibration Induced by Coupled Unbalance and Misalignment

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Chinese Journal of Mechanical Engineering 2024年第1期37卷 242-253页

作者： Yifan bao Jianfei Yao Fabrizio Scarpa Yan Li College of Mechanical and Electrical Engineering Beijing University of Chemical TechnologyBeijing 100029China State Key Laboratory of High-end Compressor and System Technology Beijing 100029China Beijing Key Laboratory of High-end Mechanical Equipment Health Monitoring and Self-Recovery Beijing University of Chemical TechnologyBeijing 100029China Key Lab of Engine Health Monitoring-Control and Networking of Ministry of Education Beijing University of Chemical TechnologyBeijing 100029China Bristol Composites Institute(ACCIS) University of BristolBristol BS81TRUK Dynamics and Control Research Group(DCRG) University of BristolBristol BS81TRUK

This paper proposes a modified iterative learning control(MILC)periodical feedback-feedforward algorithm to reduce the vibration of a rotor caused by coupled unbalance and parallel *** control of the vibration of the rotor is provided by an active magnetic actuator(AMA).The iterative gain of the MILC algorithm here presented has a self-adjustment based on the magnitude of the *** filters are adopted to extract the synchronous(1×Ω)and twice rotational frequency(2×Ω)components of the rotor *** the notch frequency of the filter and the size of feedforward storage used during the experiment have a real-time adaptation to the rotational *** method proposed in this work can provide effective suppression of the vibration of the rotor in case of sudden changes or fluctuations of the rotor *** and experiments using the MILC algorithm proposed here are carried out and give evidence to the feasibility and robustness of the technique proposed.

关键词： Rotor vibration suppression Modified iterative learning control Unbalance Parallel misalignment Active magnetic actuator