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Meteorological and sea ice anomalies in the western Arctic Ocean during the 2018-2019 ice season:a Lagrangian study

Advances in Polar Science 2022年第3期33卷 204-219页

作者： LEI Ruibo ZHANG Fanyi zhai mengxi Key Laboratory of Polar Science MNRPolar Research Institute of ChinaShanghai 200136China Chinese Antarctic Center of Surveying and Mapping Wuhan UniversityWuhan 430079China

Rapid changes in the Arctic climate and those in Arctic sea ice in recent decades are closely *** this study,we used atmospheric reanalysis data and satellite remote sensing products to identify anomalies of meteorological and sea ice conditions during the ice season of 2018-2019 relative to climatological means using a Lagrangian *** obtained the anomalies along the drifting trajectories of eight sea ice mass balance buoys between the marginal ice zone and the pack ice zone in the western Arctic Ocean(~160°W-170°W and 79°N-85°N)from September 2018 toAugust *** temporary collapse of the Beaufort High and a strong positive Arctic Dipole in the winter of 2018-2019 drove the three buoys in the north to drift gradually northeastward and merge into the Transpolar Drift *** most prominent positive temperature anomalies in 2018-2019 along the buoy trajectories relative to 1979-2019 climatology occurred in autumn,early winter,and April,and were concentrated in the southern part of the study area;these anomalies can be partly related to the seasonal and spatial patterns of heat release from the Arctic ice-ocean system to the *** the southern part of the study area and in autumn,the sea ice concentration in 2018-2019 was higher than that averaged over the past 10 ***,we found no ice concentration anomalies for other regions or *** sea ice thickness in the freezing season and the snow depth by the end of the winter of 2018-2019 can also be considered as *** the wind speed in 2018-2019 was slightly lower than that in 1979-2019,the speed of sea ice drift and its ratio to wind speed were significantly higher than the *** 2019,the sea ice surface began to melt at the end of June,which was close to the 1988-2019 ***,spatial variations in the onsets ofsurface melt in 2019 differed from the climatology,and can be explained by the prevalence of a high-pressure system in the south of the Be

关键词： sea ice air temperature climate snow motion Arctic Ocean

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Characterization of the unprecedented polynya events north of Greenland in 2017/2018 using remote sensing and reanalysis data

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Acta Oceanologica Sinica 2020年第9期39卷 5-17页

作者： Ruibo Lei Dawei Gui Zhouli Yuan Xiaoping Pang Ding Tao mengxi zhai MNR Key Laboratory for Polar Science Polar Research Institute of ChinaShanghai 200136China Chinese Antarctic Center of Surveying and Mapping Wuhan UniversityWuhan 430072China

Based on an ice concentration threshold of 90%,it has been identified that two polynya events occurred in the region north of Greenland during the 2017/2018 ice *** winter event lasted from February 20 to March 3,2018 and the summer event persisted from August 2 to September 5,*** minimum ice concentration derived from Advanced Microwave Scanning Radiometer 2(AMSR2)observations was 72%and 65%during the winter and summer events,*** occurrence of both events can be related to strengthened southerly winds associated with an increased east-west zonal surface level air pressure gradient across the north Greenland due to perturbation of mid-troposphere polar *** relatively warm air temperature during the 2017/2018 freezing season in comparison with previous years,together with the occurrence of the winter polynya,formed favourable pre-conditions for ice field fracturing in summer,which promoted the formation of the summer *** southerly winds and increased cover of new ice over the open water were the dominant factors for the disappearance of the winter polynya,whereas increased ice inflow from the north was the primary factor behind the closure of the summer ***-1 Synthetic Aperture Radar(SAR)images were found better suited than AMSR2 observations for quantification of a new ice product during the polynya event because the SAR images have high potential for mapping of different sea ice regimes with finely spatial *** unprecedented polynya events north of Greenland in 2017/2018 are important from the perspective of Arctic sea ice loss because they occurred in a region that could potentially be the last“Arctic sea ice refuge”in future summers.

关键词： sea ice ice concentration ice motion polynya Greenland Arctic Ocean

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睡眠质量与抑郁症状在青少年网络成瘾与自杀意念间的链式中介作用

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护理学杂志 2024年第11期39卷 90-92,100页

作者：肖琛嫦翟萌曦严婧琰俞斌燕虹罗健赵光红武汉城市学院医学部湖北武汉430083 武汉大学公共卫生学院

目的了解睡眠质量与抑郁症状在青少年网络成瘾与自杀意念间的作用,为针对性干预提供参考。方法方便选取武汉市2所中学的初中与高中学生509人,采用一般资料调查问卷、网络成瘾量表、自杀筛查量表简版、匹兹堡睡眠质量指数、流调中心抑郁... 详细信息

目的了解睡眠质量与抑郁症状在青少年网络成瘾与自杀意念间的作用,为针对性干预提供参考。方法方便选取武汉市2所中学的初中与高中学生509人,采用一般资料调查问卷、网络成瘾量表、自杀筛查量表简版、匹兹堡睡眠质量指数、流调中心抑郁量表进行问卷调查,构建并检验链式中介模型。结果青少年网络成瘾倾向占25.74%,睡眠质量较差占11.79%,有抑郁症状占27.90%,在过去1年有自杀意念占45.97%。网络成瘾直接影响自杀意念(直接效应占总效应的60.20%);睡眠质量与抑郁症状在网络成瘾与自杀意念关系中存在链式中介作用(间接效应占总效应的7.65%)。结论部分青少年存在网络成瘾倾向、睡眠不佳、抑郁症状和自杀意念。网络成瘾可直接影响自杀意念,还通过影响睡眠质量或引发抑郁症状间接对自杀意念产生影响。学校和家长应采取针对性策略应对,以保护青少年身心健康。

关键词：青少年中学生网络成瘾自杀意念睡眠质量抑郁症状中介效应

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Physics of Arctic landfast sea ice and implications on the cryosphere: an overview

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Advances in Polar Science 2021年第4期32卷 281-294页

作者： zhai mengxi Matti LEPPÄRANTA Bin CHENG LEI Ruibo ZHANG Fanyi Key Laboratory of Polar Science MNRPolar Research Institute of ChinaShanghai 200136China University of Helsinki Helsinki Fi-00014Finland Finnish Meteorological Institute Helsinki Fi-00101Finland

Landfast sea ice(LFSI)is a criticalcomponent of the Arctic sea ice cover,and is changing as a result of Arctic amplification of climate *** in coastal areas,LFSI is of great significance to the physical and ecological systems of the Arctic shelf and in local indigenous *** present an overview of the physics of Arctic LFSI and the associated implications on the *** is kept in place by four *** evolution of LFSI is mostly determined by thermodynamic processes,and can therefore be usedas an indicator of local climate *** also present the dynamic processes that are active prior to the formation of LFSI,and those that are involved in LFSI freeze-up and *** length,thickness and extent of Arctic LFSI are decreasing andshowing different trends in different seas,and therefore,causing environmental and climatic *** improved coordination of Arctic LFSI observation is needed with a unified and systematic observation network supported by cooperation between scientists and indigenous communities,as well as a better application of remote sensing data to acquire detailed LFSI cryosphere physical parameters,hence revolving both its annual cycle and long-term *** investigations combining in situ measurements,satellite remote sensing and numerical modeling are needed to improve our understanding of the physical mechanisms of LFSI seasonal changes and their impacts on the environment and climate.

关键词： landfast sea ice Arctic Ocean remote sensing mass balance

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Anomalous extensive landfast sea ice in the vicinity of Inexpressible Island, Antarctica

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Advances in Polar Science 2019年第4期30卷 406-411页

作者： zhai mengxi ZHAO Tiancheng HUI Fengming CHENG Xiao LIUAobo YUAN Jiawei YU Yining DING Yifan MNR Key Laboratory for Polar Science Polar Research Institute of ChinaShanghai 200136China School of Environmental Science Nanjing Xiaozhuang UniversityNanjing 211171China School of Geospatial Engineering and Science Sun Yat-Sen UniversityGuangzhou 510275China College of Global Change and Earth System Science Beijing Normal UniversityBeijing 100875China

On 10 December 2017,a Chinese research vessel R/V Xuelong encountered an extensive area of landfast ice offshore Inexpressible Island(Antarctica)near the location where the fifth Chinese Antarctic research station is to be *** multi-source satellite images and weather data,we analyzed the ice conditions during the event season and reconstructed the development of landfast *** stages in late September and early October were identified as contributing to the final ice *** two events are highly related to local-and large-scale weather *** images from 2003 to 2017 showed that four in fifteen years experienced severe landfast ice conditions,suggesting that it is not a rare phenomenon.

关键词： Inexpressible Island Antarctic landfast ice Chinese Antarctic research station

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Model simulations of the annual cycle of the landfast ice thickness in the East Siberian Sea

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Advances in Polar Science 2015年第2期26卷 168-178页

作者： YANG Yu Matti Leppranta LI Zhijun Bin Cheng zhai mengxi Denis Demchev Department of Basic Sciences Shenyang Institute of Engineering Department of Physics University of Helsinki State Key Laboratory of Coastal and Offshore Engineering Dalian University of Technology Finnish Meteorological Institute Beijing Normal University Nansen International Environmental Remote Sensing Centre (NIERSC)

The annual cycle of the thickness and temperature of landfast sea ice in the East Siberian Sea has been examined using a one-dimensional thermodynamic model. The model was calibrated for the year August 2012-July 2013, forced using the data of the Russian weather station Kotel＇ny Island and ECMWF reanalyses. Thermal growth and decay of ice were reproduced well, and the maximum annual ice thickness and breakup day became 1.64 m and the end of July. Oceanic heat flux was 2 W.m^-2 in winter and raised to 25 W.m^-2 in summer, albedo was 0.3-0.8 depending on the surface type （snow/ice and wet/dry）. The model outcome showed sensitivity to the albedo, air temperature and oceanic heat flux. The modelled snow cover was less than 10 cm having a small influence on the ice thickness. In situ sea ice thickness in the East Siberian Sea is rarely available in publications. This study provides a method for quantitative ice thickness estimation by modelling. The result can be used as a proxy to understand the sea ice conditions on the Eurasian Arctic coast, which is important for shipping and high-resolution Arctic climate modelling.

关键词： landfast sea ice New Siberian Islands ice growth ice decay oceanic heat flux snow albedo

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ALTERNATING OPTIMIZATION METHOD FOR ISOGEOMETRIC TOPOLOGY OPTIMIZATION WITH STRESS CONSTRAINTS

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Journal of Computational Mathematics 2024年第1期42卷 134-155页

作者： Xiaoya zhai School of Mathematical Sciences University of Science and Technology of ChinaHefei 230071China

Topology optimization (TO) has developed rapidly recently. However, topology optimization with stress constraints still faces many challenges due to its highly non-linear properties which will cause inefficient computation, iterative oscillation, and convergence guarantee problems. At the same time, isogeometric analysis (IGA) is accepted by more and more researchers, and it has become one important tool in the field of topology optimization because of its high fidelity. In this paper, we focus on topology optimization with stress constraints based on isogeometric analysis to improve computation efficiency and stability. A new hybrid solver combining the alternating direction method of multipliers and the method of moving asymptotes (ADMM-MMA) is proposed to solve this problem. We first generate an initial feasible point by alternating direction method of multipliers (ADMM) in virtue of the rapid initial descent property. After that, we adopt the method of moving asymptotes (MMA) to get the final results. Several benchmark examples are used to verify the proposed method, and the results show its feasibility and effectiveness.

关键词： Isogeometric topology optimization Stress constraints The ADMM-MMA solver

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DCVAE-adv:A Universal Adversarial Example Generation Method for White and Black Box Attacks

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Tsinghua Science and Technology 2024年第2期29卷 430-446页

作者： Lei Xu Junhai zhai College of Mathematics and Information Science Hebei UniversityBaoding 071002China

Deep neural network(DNN)has strong representation learning ability,but it is vulnerable and easy to be fooled by adversarial *** order to handle the vulnerability of DNN,many methods have been *** general idea of existing methods is to reduce the chance of DNN models being fooled by observing some designed adversarial examples,which are generated by adding perturbations to the original *** this paper,we propose a novel adversarial example generation method,called *** from the existing methods,DCVAE-adv constructs adversarial examples by mixing both explicit and implicit perturbations without using original ***,the proposed method can be applied to both white box and black box *** addition,in the inference stage,the adversarial examples can be generated without loading the original images into memory,which greatly reduces the memory *** compared DCVAE-adv with three most advanced adversarial attack algorithms:FGSM,AdvGAN,and AdvGAN++.The experimental results demonstrate that DCVAE-adv is superior to these state-of-the-art methods in terms of attack success rate and transfer ability for targeted *** code is available at https://***/xzforeverlove/DCVAE-adv.

关键词： deep neural network adversarial examples white box attack black box attack robustness

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Not in Control,but Liable?Attributing Human Responsibility for Fully Automated Vehicle Accidents

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Engineering 2024年第2期33卷 121-132页

作者： Siming zhai Lin Wang Peng Liu Center for Psychological Sciences Zhejiang UniversityHangzhou 310063China Department of Library and Information Science Incheon National UniversityIncheon 22012Republic of Korea

Human agency has become increasingly limited in complex systems with increasingly automated decision-making *** instance,human occupants are passengers and do not have direct vehicle control in fully automated cars(i.e.,driverless cars).An interesting question is whether users are responsible for the accidents of these *** ethical and legal analyses frequently argue that individuals should not bear responsibility for harm beyond their ***,we consider human judgment of responsibility for accidents involving fully automated cars through three studies with seven experiments(N=2668).We compared the responsibility attributed to the occupants in three conditions:an owner in his private fully automated car,a passenger in a driverless robotaxi,and a passenger in a conventional taxi,where none of these three occupants have direct vehicle control over the involved vehicles that cause identical pedestrian *** contrast to normative analyses,we show that the occupants of driverless cars(private cars and robotaxis)are attributed more responsibility than conventional taxi *** dilemma is robust across different contexts(e.g.,participants from China vs the Republic of Korea,participants with first-vs third-person perspectives,and occupant presence vs absence).Furthermore,we observe that this is not due to the perception that these occupants have greater control over driving but because they are more expected to foresee the potential consequences of using driverless *** findings suggest that when driverless vehicles(private cars and taxis)cause harm,their users may face more social pressure,which public discourse and legal regulations should manage appropriately.

关键词： Fully automated vehicle accidents Responsibility attribution Controllability Foreseeability

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Mechanism of microarc oxidation on AZ91D Mg alloy induced byβ-Mg_(17)Al_(12) phase

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International Journal of Minerals,Metallurgy and Materials 2024年第4期31卷 712-724页

作者： Dajun zhai Xiaoping Li Jun Shen College of Materials Science and Engineering Chongqing UniversityChongqing 400044China

This work proposed a strategy of indirectly inducing uniform microarc discharge by controlling the content and distribution ofβ-Mg_(17)Al_(12)phase in AZ91D Mg *** kinds of nano-particles(ZrO_(2)and TiO_(2))were designed to be added into the substrate of Mg alloy by friction stir processing(FSP).Then,Mg alloy sample designed with different precipitated morphology ofβ-Mg_(17)Al_(12)phase was treated by microarc oxidation(MAO)in Na_(3)PO_(4)/*** characteristics and performance of the MAO coating was analyzed using scanning electron microscopy(SEM),energy dispersive spectrometer(EDS),X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS),contact angle meter,and potentiodynamic *** was found that the coarseα-Mg grains in extruded AZ91D Mg alloy were refined by FSP,and theβ-Mg_(17)Al_(12)phase with reticular structure was broken and *** nano-ZrO_(2)particles were pinned at the grain boundary by FSP,which refined theα-Mg grain and promoted the precipitation ofβ-Mg_(17)Al_(12)phase in *** effectively inhibited the“cascade”phenomenon of microarcs,which induced the uniform distribution of discharge *** MAO coating on Zr-FSP sample had good wettability and corrosion ***,TiO_(2)particles were hardly detected in the coating on TiFSP sample.

关键词： AZ91D Mg alloy microarc oxidation friction stir processing ZrO_(2) TiO_(2) β-Mg_(17)Al_(12)

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