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A Review on the Mullins Effect in Tough Elastomers and Gels

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Acta Mechanica Solida Sinica 2024年第2期37卷 181-214页

作者： Lin Zhan Shaoxing Qu Rui Xiao MOE Key Lab of Disaster forecast and Control in Engineering College of Mechanics and Construction EngineeringJinan UniversityGuangzhou510632China State Key Laboratory of Fluid Power and Mechatronic System Key Laboratory of Soft Machines and Smart Devices of Zhejiang ProvinceDepartment of Engineering MechanicsZhejiang UniversityHangzhou310027China

Tough elastomers and gels have garnered broad research interest due to their wide-ranging potential ***,during the loading and unloading cycles,a clear stress softening behavior can be observed in many material systems,which is also named as the Mullins *** this work,we aim to provide a complete review of the Mullins effect in soft yet tough materials,specifically focusing on nanocomposite gels,double-network hydrogels,and multi-network *** first revisit the experimental observations for these soft *** then discuss the recent developments of constitutive models,emphasizing novel developments in the damage mechanisms or network *** phenomenological models will also be briefly *** attention is then placed on the anisotropic and multiaxial modeling *** is demonstrated that most of the existing models fail to accurately predict the multiaxial data,posing a significant challenge for developing future anisotropic models tailored for tough gels and elastomers.

关键词： Mullins effect Double-network hydrogels Nanocomposite gels Multi-network elastomers Anisotropic damage model Multiaxial model

In-situ forming ultra-mechanically sensitive materials for high-sensitivity stretchable fiber strain sensors

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National Science Review 2024年第6期11卷 254-263页

作者： Rouhui Yu Changxian Wang Xiangheng Du Xiaowen Bai Yongzhong Tong Huifang Chen Xuemei Sun Jing Yang Naoji Matsuhisa Huisheng Peng Meifang Zhu Shaowu Pan State Key Laboratory for Modification of Chemical Fibers and Polymer Materials College of Materials Science and Engineering Donghua University MOE Key Lab of Disaster forecast and Control in Engineering School of Mechanics and Construction Engineering Jinan University State Key Laboratory of Molecular Engineering of Polymers Department of Macromolecular Science and Institute of Fiber Materials and Devices Fudan University department of Cardiology Shanghai Xuhui Central HospitalZhongshan-Xuhui Hospital Fudan University Research Center for Advanced Science and Technology and Institute of Industrial Science The University of Tokyo

Fiber electronics with flexible and weavable features can be easily integrated into textiles for wearable applications. However, due to small sizes and curved surfaces of fiber materials, it remains challenging to load robust active layers, thus hindering production of high-sensitivity fiber strain sensors. Herein, functional sensing materials are firmly anchored on the fiber surface in-situ through a hydrolytic condensation *** anchoring sensing layer with robust interfacial adhesion is ultra-mechanically sensitive, which significantly improves the sensitivity of strain sensors due to the easy generation of microcracks during stretching. The resulting stretchable fiber sensors simultaneously possess an ultra-low strain detection limit of 0.05%, a high stretchability of 100%, and a high gauge factor of 433.6, giving 254-folds enhancement in sensitivity. Additionally, these fiber sensors are soft and lightweight, enabling them to be attached onto skin or woven into clothes for recording physiological signals, e.g. pulse wave velocity has been effectively obtained by them. As a demonstration, a fiber sensor-based wearable smart healthcare system is designed to monitor and transmit health status for timely intervention. This work presents an effective strategy for developing high-performance fiber strain sensors as well as other stretchable electronic devices.

关键词： fiber strain sensor stretchable wearable healthcare

The Observed Near-Surface Energy Exchange Processes over Arctic Glacier in Summer

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Journal of Meteorological Research 2024年第3期38卷 600-607页

作者： Libo ZHOU Jinhuan ZHU Linlin KONG Peng LI Shupo MA Fei LI Han ZOU Meigen ZHANG Irina REPINA department of Lower Atmospheric Observation and Research Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing100029China State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing100029China department of Weather forecast Aviation Meteorological Centre of Air Traffic Management BureauCivil Aviation Administration of ChinaBeijing100015China A.M.Obukhov Institute of Atmospheric Physics Russian Academy of Sciences(RAS)Moscow119017Russian Federation

Under Arctic warming,near-surface energy transfers have significantly changed,but few studies have focused on energy exchange over Arctic glacier due to limitations in available *** this study,the atmospheric energy exchange processes over the Arctic glacier surface were analyzed by using observational data obtained in summer 2019 in comparison with those over the Arctic tundra *** energy budget over the glacier greatly differed from that over the tundra,characterized by less net shortwave radiation and downward sensible heat flux,due to the high albedo and icy *** of the incoming solar radiation was injected into the glacier in summer,leading to snow ice *** the observation period,strong daily variations in near-surface heat transfer occurred over the Arctic glacier,with the maximum downward and upward heat fluxes occurring on 2 and 6 July 2019,*** analyses suggested that the maximum downward heat flux is mainly caused by the strong local thermal contrast above the glacier surface,while the maximum upward heat transfer cannot be explained by the classical turbulent heat transfer theory,possibly caused by countergradient heat *** results indicated that the near-surface energy exchange processes over Arctic glacier may be strongly related to local forcings,but a more in-depth investigation will be needed in the future when more observational data become available.

关键词： Arctic glacier tundra energy exchange processes

Predictability of the 7·20 extreme rainstorm in Zhengzhou in stochastic kinetic-energy backscatter ensembles

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Science China Earth Sciences 2024年第7期67卷 2226-2241页

作者： Min YANG Peilong YU Lifeng ZHANG Xiaobing PAN Quanjia ZHONG Yunying LI College of Meteorology and Oceanography National University of Defense TechnologyChangsha 410073China Key Laboratory of High Impact Weather(Special) China Meteorological AdministrationChangsha 410073China Collaborative Innovation Center on forecast and Evaluation of Meteorological Disasters/Key Laboratory of Meteorological Disaster Ministry of Education/Joint International Research Laboratory of Climate and Environment ChangeNanjing University of Information Science and TechnologyNanjing 210044China department of Ocean Science Hong Kong University of Science and TechnologyHong Kong 999077China

The scale-dependent predictability of the devastating 7·20 extreme rainstorm in Zhengzhou,China in 2021 was investigated via ensemble experiments,which were perturbed on different scales using the stochastic kinetic-energy backscatter(SKEB)scheme in the WRF model,with the innermost domain having a 3-km grid *** daily rainfall(RAIN24h)and the cloudburst during 1600-1700 LST(RAIN1h)were *** demonstrated that with larger perturbation scales,the ensemble spread for the rainfall maximum widens and rainfall forecasts become closer to the *** ensembles with mesoscale or convective-scale perturbations,RAIN1h loses predictability at scales smaller than 20 km and RAIN24h is predictable for all *** in ensembles with synoptic-scale perturbations,the largest scale of predictability loss extends to 60 km for both RAIN1h and ***,the average positional error in forecasting the heaviest rainfall for RAIN24h(RAIN1h)was 400 km(50-60)*** southerly low-level jet near Zhengzhou was assumed to be directly responsible for the forecast uncertainty of *** rapid intensification in low-level cyclonic vorticity,mid-level divergence,and upward motion concomitant with the jet dynamically facilitated the *** analysis of the divergent,rotational and vertical kinetic spectra and the corresponding error spectra showed that the error kinetic energy at smaller scales grows faster than that at larger scales and saturates more quickly in all ***-scale perturbations not only boost larger-scale error growth but are also conducive to error growth at all scales through a downscale cascade,which indicates that improving the accuracy of larger-scale flow forecast may discernibly contributes to the forecast of cloudburst intensity and position.

关键词： Stochastic kinetic-energy backscatter(SKEB) Extreme rainfall Ensemble forecast Predictability

Assessing the Performance of CMIP6 Models in Simulating Droughts across Global Drylands

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Advances in Atmospheric Sciences 2024年第2期41卷 193-208页

作者： Xiaojing YU Lixia ZHANG Tianjun ZHOU Jianghua ZHENG LASG Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China Collaborative Innovation Center on forecast and Evaluation of Meteorological Disasters Nanjing University of Information Science&TechnologyNanjing 210044China University of Chinese Academy of Sciences Beijing 100049China College of Geography&Remote Sensing Sciences Xinjiang UniversityUrumqi 830046China

Both the attribution of historical change and future projections of droughts rely heavily on climate modeling. However,reasonable drought simulations have remained a challenge, and the related performances of the current state-of-the-art Coupled Model Intercomparison Project phase 6(CMIP6) models remain unknown. Here, both the strengths and weaknesses of CMIP6 models in simulating droughts and corresponding hydrothermal conditions in drylands are *** the general patterns of simulated meteorological elements in drylands resemble the observations, the annual precipitation is overestimated by ~33%(with a model spread of 2.3%–77.2%), along with an underestimation of potential evapotranspiration(PET) by ~32%(17.5%–47.2%). The water deficit condition, measured by the difference between precipitation and PET, is 50%(29.1%–71.7%) weaker than observations. The CMIP6 models show weaknesses in capturing the climate mean drought characteristics in drylands, particularly with the occurrence and duration largely underestimated in the hyperarid Afro-Asian areas. Nonetheless, the drought-associated meteorological anomalies, including reduced precipitation, warmer temperatures, higher evaporative demand, and increased water deficit conditions, are reasonably reproduced. The simulated magnitude of precipitation(water deficit) associated with dryland droughts is overestimated by 28%(24%) compared to observations. The observed increasing trends in drought fractional area,occurrence, and corresponding meteorological anomalies during 1980–2014 are reasonably reproduced. Still, the increase in drought characteristics, associated precipitation and water deficit are obviously underestimated after the late 1990s,especially for mild and moderate droughts, indicative of a weaker response of dryland drought changes to global warming in CMIP6 models. Our results suggest that it is imperative to employ bias correction approaches in drought-related studies over drylands by using CMIP6 o

关键词： droughts hydrothermal conditions drylands CMIP6 model evaluation

The Probability Density Function Related to Shallow Cumulus Entrainment Rate and Its Influencing Factors in a Large-Eddy Simulation

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Advances in Atmospheric Sciences 2024年第1期41卷 173-187页

作者： Lei ZHU Chunsong LU Xiaoqi XU Xin HE Junjun LI Shi LUO Yuan WANG Fan WANG Collaborative Innovation Center on forecast and Evaluation of Meteorological Disasters(CIC-FEMD)and Key Laboratory for Aerosol-Cloud-Precipitation of China Meteorological Administration Nanjing University of Information Science and TechnologyNanjing 210044China Nanjing Joint Institute for Atmospheric Sciences Nanjing 210019China College of Aviation Meteorology Civil Aviation Flight University of ChinaGuanghan 618307China Collaborative Innovation Center for Western Ecological Safety Lanzhou UniversityLanzhou 730000China department of Geography Hong Kong Baptist UniversityHong Kong SAR 999077China

The process of entrainment-mixing between cumulus clouds and the ambient air is important for the development of cumulus *** obtaining the entrainment rate(λ)is particularly important for its parameterization within the overall cumulus parameterization *** this study,an improved bulk-plume method is proposed by solving the equations of two conserved variables simultaneously to calculateλof cumulus clouds in a large-eddy *** results demonstrate that the improved bulk-plume method is more reliable than the traditional bulk-plume method,becauseλ,as calculated from the improved method,falls within the range ofλvalues obtained from the traditional method using different conserved *** probability density functions ofλfor all data,different times,and different heights can be well-fitted by a log-normal distribution,which supports the assumed stochastic entrainment process in previous *** analysis demonstrate that the relationship betweenλand the vertical velocity is better than other thermodynamic/dynamical properties;thus,the vertical velocity is recommended as the primary influencing factor for the parameterization ofλin the *** results of this study enhance the theoretical understanding ofλand its influencing factors and shed new light on the development ofλparameterization.

关键词： large-eddy simulation cumulus clouds entrainment rate probability density functions spatial and temporal distribution

Recent Enhanced Deep Troposphere-to-Stratosphere Air Mass Transport Accompanying the Weakening Asian Monsoon

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Journal of Meteorological Research 2024年第4期38卷 708-719页

作者： Bin CHEN Jianzhong MA Wei ZHANG Jianchun BIAN Tianliang ZHAO Xiangde XU State Key Laboratory of Severe Weather Chinese Academy of Meteorological SciencesChina Meteorological AdministrationBeijing100081China department of Plants Soils and ClimateUtah State UniversityUT84322USA Key Laboratory of Middle Atmosphere and Global Environment Observation Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China Collaborative Innovation Center on forecast and Evaluation of Meteorological Disasters Key Laboratory for Aerosol-Cloud-Precipitation of China Meteorological AdministrationNanjing University of Information Science&TechnologyNanjing 210044China

The Asian monsoon(AM) region is a well-known region with prevailing stratosphere–troposphere exchange(STE).However,how the STE across this region changes with the weakening AM remains ***,we particularly diagnose the air mass transport between the planetary boundary layer(PBL) and the stratosphere over the AM region during 1992–2017 using the Lagrangian particle dispersion model FLEXPART based on the ERA-Interim reanalysis *** results show that both the downward and upward deep STEs exhibit a detectable increasing trend,while the latter,namely,the deep troposphere-to-stratosphere transport(DTST),is relatively more *** analysis reveals that the long-term trend of DTST over the AM region could be partly attributed to changes in the Pacific Walker circulation and the air temperature(especially at upper levels).Additionally,it is found that DTST increases markedly over the tropical oceanic regions,while the increasing DTST into the stratosphere can be attributed to the enhanced air masses originated from the PBL over the terrestrial regions,where large amounts of pollutant emissions *** results imply that the influence of the DTST on the chemical composition and the climate of the stratosphere over the AM region is expected to become increasingly important,and is thereby of relevance to climate projection in an evolving climate.

关键词： stratosphere–troposphere exchange(STE) air mass transport deep troposphere-to-stratosphere transport(DTST) Asian monsoon(AM) pollution

Projected changes in Köppen-Trewartha climate zones under 1.5-4℃global warming targets over mid-high latitudes of Northern Asia using an ensemble of RegCM4 simulations

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Advances in Climate Change Research 2024年第2期15卷 185-196页

作者： Jie WU Xue-Jie GAO Xian-Bing TANG Filippo GIORGI School of Geography and Environmental Engineering Gannan Normal UniversityGanzhou 341000China Climate Change Research Center Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China Collaborative Innovation Center on forecast and Evaluation of Meteorological Disasters Nanjing University of Information Science&TechnologyNanjing 210044China University of Chinese Academy of Sciences Beijing 100049China The Abdus Salam International Centre for Theoretical Physics Trieste 34100Italy

Mid-high latitude Northern Asia is one of the most vulnerable and sensitive areas to global warming,but relatively less studied *** used an ensemble of a regional climate model(RegCM4)projections to assess future changes in surface air temperature,precipitation and Köppen-Trewartha(K-T)climate types in Northern Asia under the 1.5-4℃global warming ***4 is driven by five CMIP5 global models over an East Asia domain at a grid spacing of 25 *** of the present day(1986-2005)simulations shows that the ensembles of RegCM4(ensR)and driving GCMs(ensG)reproduce the major characters of the observed temperature,precipitation and K-T climate zones reasonably *** and more realistic spatial detail is found in RegCM4 compared to the driving GCMs.A general warming and overall increases in precipitation are projected over the region,with these changes being more pronounced at higher warming *** projected warming by ensR shows different spatial patterns,and is in general lower,compared to ensG in most months of the year,while the percentage increases of precipitation are maximum during the cold *** future changes in K-T climate zones are characterized by a substantial expansion of Dc(temperature oceanic)and retreat of Ec(sub-arctic continental)over the region,reaching∼20%under the 4℃warming *** most notable change in climate types in ensR is found over Japan(∼60%),followed by Southern Siberia,Mongolia,and the Korean Peninsula(∼40%).The largest change in the K-T climate types is found when increasing from 2 to 3℃.The results will help to better assess the impacts of climate change and in implementation of appropriate adaptation measures over the region.

关键词： Mid-high latitudes of Northern Asia Köppen climate zones Global warming targets Regional climate model

Spatial and Temporal Analysis of Maximum and Minimum Temperature Trends in Northern Sudan during (1990-2019)

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Journal of Geoscience and Environment Protection 2024年第5期12卷 266-288页

作者： Elhag Gamreldin Monzer Hamadalnel Collaborative Innovation Center on forecast and Evaluation of Meteorological Disasters School of Atmospheric Sciences Nanjing University of Information Science and Technology Nanjing China Sudan Meteorological Authority (SMA) Khartoum Sudan department of Astronomy and Meteorology Faculty of Science and Technology Omdurman Islamic University Omdurman Sudan

The study addresses an urgent and globally significant issue of climate change by focusing on the detailed spatial and temporal analysis of temperature trends in Northern Sudan. It fills a critical research gap by providing localized data over a substantial period (1990-2019), which could help in understanding the nuanced impacts of climate change in Sahel regions like Northern Sudan. In addition, the comprehensive coverage of both spatial and temporal dimensions, supported by a substantial dataset from five meteorological stations, provides a thorough understanding of the subject area. The utilization of robust statistical methods (Mann-Kendall test and Sen’s slope analysis) for analyzing temperature trends adds scientific rigor and credibility to the findings. Our results reveal a consistently increasing trend in maximum temperatures across most stations, particularly during the hot season (AMJ). However, the wet season (JAS) shows high maximum temperatures but no significant trend. Moreover, significant increasing trends in minimum temperatures were observed in all stations except Abu Hamed, where the trend, although increasing, did not reach statistical significance during the hot and cold seasons, and the coldest temperatures were observed during the cold season. These findings underscore the complex temperature dynamics in Northern Sudan and highlight the need for continued monitoring and adaptive measures in response to ongoing climate changes in the region.

关键词： Climate Change Northern Sudan Temperature Trend Seasonal Analysis