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Influence of pressure disturbance wave on dynamic response characteristics of liquid film seal for multiphase pump

Petroleum Science 2024年第3期21卷 2048-2065页

作者： Qing-Ping Li Jin-Ya zhang Jia-Xiang zhang Yong-xue zhang CNOOC Research Institute Company Limited Beijing100028China State Key Laboratory of Natural Gas Hydrate Beijing100028China College of Mechanical and Transportation Engineering China University of PetroleumBeijing2249China

Slug flow or high GVF(Gas Volume Fraction)conditions can cause pressure disturbance waves and alternating loads at the boundary of mechanical seals for multiphase pumps,endangering the safety of multiphase pump *** mechanical seal model is simplified by using periodic boundary conditions and numerical calculations are carried out based on the Zwart-Gerber-Belamri cavitation ***(User Define Function)programs such as structural dynamics equations,alternating load equations,and pressure disturbance equations are embedded in numerical calculations,and the dynamic response characteristics of mechanical seal are studied using layered dynamic mesh *** results show that when the pressure disturbance occurs at the inlet,as the amplitude and period of the disturbance increase,the film thickness gradually *** the fundamental reason for the hysteresis of the film thickness change is that the pressure in the high-pressure area cannot be restored in a timely *** maximum value of leakage and the minimum value of axial velocity are independent of the disturbance period and determined by the disturbance *** mutual interference between enhanced waves does not have a significant impact on the film thickness,while the front wave in the attenuated wave has a promoting effect on the subsequent film thickness changes,and the fluctuation of the liquid film cavitation rate and axial velocity under the attenuated wave condition deviates from the initial *** with pressure disturbance conditions,alternating load conditions have a more significant impact on film thickness and *** actual operation,it is necessary to avoid alternating load conditions in multiphase pump mechanical seals.

关键词： Multiphase pump Liquid film seal Pressure disturbance wave Dynamic response characteristics

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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

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Impact response and energy absorption of metallic buffer with entangled wire mesh damper

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Defence Technology（防务技术） 2024年第5期35卷 137-150页

作者： Chao Zheng Jun Wu Mangong zhang Xin xue Institute of Metal Rubber&Vibration Noise School of Mechanical Engineering and AutomationFuzhou UniversityFuzhou 350116China Wuhan Second Ship Design and Research Institute Wuhan 430205China

An innovative metallic buffer consisting of series-connected hat-shaped entangled wire mesh damper(EWMD)and parallel springs are proposed in this work to enhance the reliability of engineering *** impact response and the energy dissipation mechanism of hat-shaped EWMD under different quasi-static compression deformations(2-7 mm)and impact heights(100-200 mm)are investigated using experimental and numerical *** results demonstrate distinct stages in the quasi-static mechanical characteristics of hat-shaped EWMD,including stiffness softening,negative stiffness,and stiffness *** loss factor gradually increases with increasing compression deformation before entering the stiffness hardening *** impact loads,the hat-shaped EWMD exhibits optimal impact energy absorption when it enters the negative stiffness stage(150 mm),resulting in the best impact isolation effect of metallic ***,the impact energy absorption significantly decreases when hat-shaped EWMD enters the stiffness hardening ***,quasi-static compression analysis after experiencing different impact loads reveals the disappearance of the negative stiffness ***,with increasing impact loads,the stiffness hardening point progressively shifts to an earlier stage.

关键词： Metallic buffer Hat-shaped EWMD Drop impact Energy absorption characteristics Mechanical behavior

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ContextAug:model-domain failing test augmentation with contextual information

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Frontiers of Computer Science 2024年第2期18卷 43-60页

作者： Zhuo zhang Jianxin xue Deheng YANG Xiaoguang MAO School of Information Technology and Engineering Guangzhou College of CommerceGuangzhou 511363China School of Computer and Information Engineering Institute for Artificial IntelligenceShanghai Polytechnic UniversityShanghai 201209China College of Computer National University of Defense TechnologyChangsha 410073China

In the process of software development,the ability to localize faults is crucial for improving the efficiency of *** speaking,detecting and repairing errant behavior at an early stage of the development cycle considerably reduces costs and development *** have tried to utilize various methods to locate the faulty ***,failing test cases usually account for a small portion of the test suite,which inevitably leads to the class-imbalance phenomenon and hampers the effectiveness of fault ***,in this work,we propose a new fault localization approach named *** obtaining dynamic execution through test cases,ContextAug traces these executions to build an information model;subsequently,it constructs a failure context with propagation dependencies to intersect with new model-domain failing test samples synthesized by the minimum variability of the minority feature *** contrast to traditional test generation directly from the input domain,ContextAug seeks a new perspective to synthesize failing test samples from the model domain,which is much easier to augment test *** conducting empirical research on real large-sized programs with 13 state-of-the-art fault localization approaches,ContextAug could significantly improve fault localization effectiveness with up to 54.53%.Thus,ContextAug is verified as able to improve fault localization effectiveness.

关键词： context fault localization test cases

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Recursive Projected Filter Algorithm with Binary-Valued Observations

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Journal of Systems Science & Complexity 2024年第5期37卷 1832-1860页

作者： zhang Xiaoyan WANG Ying xue Wenchao ZHAO Yanlong Key Laboratory of Systems and Control Institute of Systems Science Academy of Mathematics and Systems Science Chinese Academy of Sciences School of Mathematical Sciences University of Chinese Academy of Sciences

This paper focuses on the state estimate for a class of systems with both process noise and measurement noise under binary-valued observations, in which the Gaussian assumption on the predicted density of the state is not required. A recursive projected filter algorithm with time-varying thresholds is constructed to estimate the state under binary-valued observations. The time-varying thresholds are designed as the prediction value of the measurement, which can provide more information about the system state. The convergence property is established with some suitable stability,boundedness and observability conditions. In particular, the estimation error between state and estimate is proved to be asymptotically bounded in the mean-square sense, whose upper bound is related to the variance of process noise. Finally, the theoretical results are demonstrated via numerical examples of first-order and high-order systems.

关键词： Binary-valued observations convergence recursive filter time-varying thresholds

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Intensified warming suppressed the snowmelt in the Tibetan Plateau

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Advances in Climate Change Research 2024年第3期15卷 452-463页

作者： Xiang LI Peng CUI xue-Qin zhang Fang zhang Key Lab of Land Surface Pattern and Simulation Institute of Geographic Sciences and Natural Resources ResearchBeijing 100101China University of Chinese Academy of Sciences Beijing 100049China China‒Pakistan Joint Research Center on Earth Sciences Chinese Academy of Sciences and Higher Education CommissionIslamabad 45320Pakistan

Understanding how hydrological factors interrelate is crucial when examining the impact of climate warming on ***,these connections are often overlooked,leading to an unclear relationship between temperature and *** study investigates the complex interplay between temperature and snowmelt in the Tibetan Plateau from 1961 to 2020,focusing on how extreme high-temperature events affect the frequency of extreme *** a structural equation model,we detected three temperature-related factors that predominantly influenced snowmelt and extreme *** annual average temperature was found to have a significant indirect impact on snowmelt,mediated by changes in snowfall,snow depth and snow *** contrast,high-temperature days(daily maximum temperatures exceeding the 90th percentile)and heat waves(at least three consecutive high-temperature days)negatively affected extreme snowmelt directly or *** direct effect of increasing extreme temperature events was associated with an earlier onset of high-temperature periods,which accelerated snowmelt and shortened the duration of extreme snowmelt ***,the reduction in snow cover owing to warming emerged as a main factor suppressing snowmelt and extreme snowmelt *** also revealed spatiotemporal variations in the temperature‒snowmelt relationship that highly depended on changes in snowmelt *** study elucidated why warming suppresses snowmelt and extreme snowmelt events in the Tibetan Plateau,highlighting the mediating roles of snow-related and phenological *** findings will provide scientific support for climate simulation and water management policymaking in alpine regions worldwide.

关键词： Climate change Extreme temperature Snowmelt Structural equation model Tibetan Plateau

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Fully sprayed MXene-based high-performance flexible piezoresistive sensor for image recognition

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Nano Materials Science 2024年第1期6卷 77-85页

作者： Zhi-Dong zhang xue-Feng Zhao Qing-Chao zhang Jie Liang Hui-Nan zhang Tian-Sheng zhang Chen-Yang xue Key Laboratory of Instrumentation Science&Dynamic Measurement of Ministry of Education North University of ChinaTaiyuan030051People's Republic of China State Key Laboratory of ASIC and System Shanghai Institute of Intelligent Electronics&SystemsSchool of MicroelectronicsFudan UniversityShanghai200433People's Republic of China Shanxi Hosipital of Acupuncture and Moxibustion Taiyuan030006People's Republic of China

High-performance flexible pressure sensors provide comprehensive tactile perception and are applied in human activity monitoring,soft robotics,medical treatment,and human-computer ***,these flexible pressure sensors require extensive nano-architectural design and complicated manufacturing and are ***,a highly sensitive,flexible piezoresistive tactile sensor is designed and fabricated,consisting of three main parts:the randomly distributed microstructure on T-ZnOw/PDMS film as a top substrate,multilayer Ti_(3)C_(2)-MXene film as an intermediate conductive filler,and the few-layer Ti_(3)C_(2)-MXene nanosheetbased interdigital electrodes as the bottom *** MXene-based piezoresistive sensor with randomly distributed microstructure exhibits a high sensitivity over a broad pressure range(less than 10 kPa for 175 kPa^(-1))and possesses an out-standing permanence of up to 5000 ***,a 16-pixel sensor array is designed,and its potential applications in visualizing pressure distribution and an example of tactile feedback are *** fully sprayed MXene-based pressure sensor,with high sensitivity and excellent durability,can be widely used in,electronic skin,intelligent robots,and many other emerging technologies.

关键词： Piezoresistive sensor Ti_(3)C_(2)-MXene T-ZnOw/PDMS film Randomly distributed microstructure

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A review on plasmonic enhancement of activity and selectivity in electrocatalytic CO_(2)reduction

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Frontiers in Energy 2024年第4期18卷 399-417页

作者： Jing xue Zhenlin CHEN Yuchao zhang Jincai ZHAO Key Laboratory of Photochemistry Beijing National Laboratory for Molecular SciencesInstitute of ChemistryChinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 100049China

Utilizing plasmonic effects to assist electrochemical reactions exhibits a huge potential in tuning the reaction activities and product selectivity,which is most appealing especially in chemical reactions with multiple products,such as CO_(2)reduction reaction(CO_(2)RR).However,a comprehensive review of the development and the underlying mechanisms in plasmon-assisted electrocatalytic CO_(2)RR remains few and far ***,the fundamentals of localized surface plasmonic resonance(LSPR)excitation and the properties of typical plasmonic metals(including Au,Ag,and Cu)are ***,the potential mechanisms of plasmonic effects(such as hot carrier effects and photothermal effects)on the reaction performance in the field of plasmon-assisted electrocatalytic CO_(2)RR are summarized,which provides directions for the future development of this *** is concluded that plasmonic catalysts exhibit potential capabilities in enhancing CO_(2)RR while more in situ techniques are essential to further clarify the inner mechanisms.

关键词： localized surface plasmonic resonance(LSPR)effect plasmonic metals CO_(2)reduction reaction(CO_(2)RR) hot carrier effect photothermal effect

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Surface iodine and pyrenyl-graphdiyne co-modified Bi catalysts for highly efficient CO_(2) electroreduction in acidic electrolyte

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Nano Research 2024年第4期17卷 2381-2387页

作者： Min zhang Juan Wang Xin Rong xiu-Li Lu Tong-Bu Lu MOE International Joint Laboratory of Materials Microstructure Institute for New Energy Materials and Low Carbon TechnologiesSchool of Materials Science and EngineeringTianjin University of TechnologyTianjin 300384China

CO_(2) electroreduction to formic acid/formate would contribute to alleviating the energy and climate *** work reports a Bi-based catalyst derived from the in-situ electroreduction of Bi_(2)O_(2)CO_(3) modified with iodine and pyrenyl-graphdiyne(PGDY)on the surface for efficient electroreduction of CO_(2) in acidic electrolyte,with a high partial current density of 98.71 mA·cm^(-2) and high Faradaic efficiency(FE)>90%over the potential range from^(-1).2 to-1.5 V *** hydrogen electrode(RHE),as well as the long-term operational stability over 240 h without degradation in H-type *** results and density function theory calculations show that the synergistic effect of surface iodine and PGDY is responsible for this active and extremely stable process of CO_(2) electroreduction via lowering the energy barriers for formation of*OCHO intermediate,suppressing the competitive HER by enhancing the concentration of both K+and CO_(2) at reaction interface,as well as preventing the dissolution and re-deposition of active Bi atoms on surface during catalytic *** work provides new insight into designing highly active and stable electrocatalysts for CO_(2) reduction.

关键词： CO_(2) reduction electrocatalysis Bi-based catalysts acidic electrolyte

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NLRP3-mediated autophagy dysfunction links gut microbiota dysbiosis to tau pathology in chronic sleep deprivation

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Zoological Research 2024年第4期45卷 857-874页

作者： Na Zhao xiu Chen Qiu-Gu Chen xue-Ting Liu Fan Geng Meng-Meng Zhu Fu-Ling Yan Zhi-Jun zhang Qing-Guo Ren Department of Neurology School of MedicineSoutheast UniversityNanjingJiangsu 210009China Department of Neurology Affiliated Zhongda HospitalSoutheast UniversityNanjingJiangsu 210009China

Emerging evidence indicates that sleep deprivation(SD)can lead to Alzheimer’s disease(AD)-related pathological changes and cognitive ***,the underlying mechanisms remain *** the present study,we identified the existence of a microbiota-gut-brain axis in cognitive deficits resulting from chronic SD and revealed a potential pathway by which gut microbiota affects cognitive functioning in chronic *** findings demonstrated that chronic SD in mice not only led to cognitive decline but also induced gut microbiota dysbiosis,elevated NLRP3 inflammasome expression,GSK-3βactivation,autophagy dysfunction,and tau hyperphosphorylation in the *** with the“SD microbiota”replicated the pathological and behavioral abnormalities observed in chronic sleep-deprived ***,both the deletion of NLRP3 in NLRP3-/-mice and specific knockdown of NLRP3 in the hippocampus restored autophagic flux,suppressed tau hyperphosphorylation,and ameliorated cognitive deficits induced by chronic SD,while GSK-3βactivity was not regulated by the NLRP3 inflammasome in chronic ***,deletion of NLRP3 reversed NLRP3 inflammasome activation,autophagy deficits,and tau hyperphosphorylation induced by GSK-3βactivation in primary hippocampal neurons,suggesting that GSK-3β,as a regulator of NLRP3-mediated autophagy dysfunction,plays a significant role in promoting tau ***,gut microbiota dysbiosis was identified as a contributor to chronic SD-induced tau pathology via NLRP3-mediated autophagy dysfunction,ultimately leading to cognitive ***,these findings highlight GSK-3βas a regulator of NLRP3-mediated autophagy dysfunction,playing a critical role in promoting tau hyperphosphorylation.

关键词： Chronic sleep deprivation Tau pathology NLRP3 inflammasome Autophagy GSK-3β Microbiota-gut-brain axis

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