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heat transport in coupled inhomogeneous chains

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Chinese Physics B 2011年第6期20卷 125-130页

作者：胡涛白萌胡柯唐翌 Department of Physics Xiangtan University

We first investigate the heat transport in a network model consisting of two coupled dimerized chains. Results indicate that the thermal resistance of each chain increases with the decrease of the mass ratio γ. of the two types of atoms. Then, we find, when a light impurity or a heavy one is added in the two coupled homogeneous chains and coupled with a particle of another chain, the interface thermal resistances Rint and Rint present different dependences on the mass ratio γ Finally, a persistent circulation of energy current is observed in coupled inhomogeneous chains with two pairs of interchain coupling.

关键词： heat transport thermal resistance

Estimating the effect of shallow groundwater on diurnal heat transport in a vadose zone

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Frontiers of Earth Science 2016年第3期10卷 513-526页

作者： Jianmei JIANG Lin ZHAO Zhe ZHAI School of Chemical Engineering Tianjin University Tianjin 300072 China School of Environment Science and Engineering Tianjin University Tianjin 300072 China

The influence of shallow groundwater on the diurnal heat transport of the soil profile was analyzed using a soil sensor automatic monitoring system that continu- ously measures temperature and water content of soil profiles to simulate heat transport based on the Philip and de Vries （PDV） model. Three experiments were conducted to measure soil properties at depths of 5 cm, 10 cm, 20 cm, and 30 cm when groundwater tables reached l0 cm, 30 cm, and 60 cm （Experiments I, II, and III）. Results show that both the soil temperature near shallow groundwater and the soil water content were effectively simulated by the PDV model. The root mean square errors of the temperature at depths of 5 cm, 10 cm, and 20 cm were 1.018℃, 0.909℃, and 0.255℃, respectively. The total heat flux generated the convergent and divergent planes in space-time fields with valley values of-161.5 W-m 2 at 7：30 and -234.6 W.m2 at 11：10 in Experiments II and III, respectively. The diurnal heat transport of the saturated soil occurred in five stages, while that of saturated-unsaturated and unsaturated soil profiles occurred in four stages because high moisture content led to high thermal conductivity, which hastened the heat transport.

关键词： heat transport heat flux soil temperature,water content shallow groundwater table

Modeling Arctic Ocean heat transport and warming episodes in the 20th century caused by the intruding Atlantic Water

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Chinese Journal of Polar Science 2008年第2期19卷 159-167页

作者： Wang Jia Jin Meibing Jun Takahashi Tatsuo Suzuki Igor V Polyakov Kohei Mizobata Moto Ikeda Fancois J. Saucier Markus Meier NOAA Great Lakes Environmental Research Laboratory 4840 S State Road Ann Arbor Michigan 48108 USA International Arctic Research Center University of Alaska Fairbanks 930 Koyukuk Dr. Fairbanks AK 99775USA Frontier Research Center for Global Change 3173-25 Showamachi Kanazawa-ku Yokohama City Kanagawa236-0001 Japan Department of Ocean Science Tokyo University of Marine Science and Technology Tokyo Japan Graduate School of Earth and Environmental Science Hokkaido University Sapporo Hokkaido Japan Institute of Ocean Science University of Quebec at Rimouski 310 Ursulines Street Rimouski G5L 3A1 Canada Rossby Centre Swedish Meteorological and Hydrological Institute Sweden

This study investigates the Arctic Ocean warming episodes in the 20th century using both a high-resolution coupled global climate model and historical observations. The model, with no flux adjustment, reproduces well the Atlantic Water core temperature （AWCT） in the Arctic Ocean and shows that four largest decadalscale warming episodes occurred in the 1930s, 70s, 80s, and 90s, in agreement with the hydrographic observational data. The difference is that there was no pre-warming prior to the 1930s episode, while there were two pre-warming episodes in the 1970s and 80s prior to the 1990s, leading the 1990s into the largest and prolonged warming in the 20th century. Over the last century, the simulated heat transport via Fram Strait and the Barents Sea was estimated to be, on average, 31.32 TW and 14.82 TW, respectively, while the Bering Strait also provides 15.94 TW heat into the west- ern Arctic Ocean. heat transport into the Arctic Ocean by the Atlantic Water via Fram Strait and the Barents Sea correlates significantly with AWCT （ C = 0.75 ） at 0- lag. The modeled North Atlantic Oscillation （NAO） index has a significant correlation with the heat transport （ C = 0.37 ）. The observed AWCT has a significant correlation with both the modeled AWCT （ C =0.49） and the heat transport （ C =0.41 ）. However, the modeled NAO index does not significantly correlate with either the observed AWCT （ C = 0.03 ） or modeled AWCT （ C = 0.16 ） at a zero-lag, indicating that the Arctic climate system is far more complex than expected.

关键词： Arctic Ocean heat transport warming episodes modeling.

Experimental Investigation on Thermal Characteristics of Long Distance Loop heat Pipes

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Journal of Thermal Science 2022年第3期31卷 741-750页

作者： ZHAO Ya’nan YAN Tao LIANG Jingtao Key Laboratory of Space Energy Conversion Technology Technical Institute of Physics and ChemistryChinese Academy of SciencesBeijing100190China University of Chinese Academy of Sciences Beijing100190China

Loop heat pipes(LHPs)are attractive two-phase thermal control devices for satellites,electronics and many other applications.They are capable of transporting heat efficiently for long distances up to several meters at any orientation.This paper investigated the heat transfer characteristics of loop heat pipes with long distances and small diameter transport lines.Small stainless steel tubes of 2 mm and 3 mm in inner diameters were chosen as liquid lines and vapor lines of the LHPs.The local thermal resistances in the evaporator of the 6 m-LHP were researched and analyzed,which indicated that the thermal resistance between the aluminum block and the vapor in the vapor channel accounted for a major proportion of the total thermal resistance.The effect of heat sink temperatures on the performance of the 6 m-LHP were compared with 10°C,15°C,20°C and 25°C cooling water temperatures.Moreover,the thermal characteristics of LHPs with transport distances of 2 m and 16 m were also experimentally investigated.The 16 m-LHP could achieve a heat transfer capacity of 100 W and the 2 m-LHP could reach more than 339 W,on the premise of the evaporator temperature below 100°C.The thermal resistance of the 2 m-LHP could achieve 0.125°C/W.

关键词： loop heat pipe thermal management heat transport long distance thermal resistance

Tuning turbulent convection through rough element arrangement

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Journal of Hydrodynamics 2022年第2期34卷 308-314页

作者： Jian-zhao Wu Dao-liang Dong Bo-fu Wang Yu-hong Dong Quan Zhou Shanghai Institute of Applied Mathematics and Mechanics School of Mechanics and Engineering ScienceShanghai Key Laboratory of Mechanics in Energy EngineeringShanghai UniversityShanghai200072China

The tuning of turbulent Rayleigh-Bénard(RB)convection in a box is realized numerically by designed rough element arrangement.Considering the nonlinear dynamics of the thermal turbulence system,five models with rough elements of different widths and the same height are proposed to tune the fluid flow heat-transport capacity.Numerical simulations are performed using spectral element method for Rayleigh number in the range 10^(6)≤Ra≤10^(9) and a fixed Prandtl number Pr=0.7.It is found that heat transport is enhanced for large roughness widths as the interaction between the large-scale circulation and secondary flows inside the cavity regions between the rough elements promotes the eruptions of thermal plumes,but is suppressed for small ones as more heat are trapped inside the cavities.In all the rough models studied,different scaling exponents for the heat transport are identified and the influences of roughness arrangement on flow structure are studied.

关键词： Rayleigh-Bénard(RB)turbulence heat transport roughness arrangement

Nonequilibrium thermodynamics in cavity optomechanics

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Fundamental Research 2023年第1期3卷 75-86页

作者： Jiteng Sheng Cheng Yang Haibin Wu State Key Laboratory of Precision Spectroscopy East China Normal UniversityShanghai 200062China Collaborative Innovation Center of Extreme Optics Shanxi UniversityTaiyuan 030006China Chongqing Key Laboratory of Precision Optics Chongqing Institute of East China Normal UniversityChongqing 401120China Shanghai Research Center for Quantum Sciences Shanghai 201315China

Classical thermodynamics has been a great achievement in dealing with systems that are in equilibrium or near equilibrium.As an emerging field,nonequilibrium thermodynamics provides a general framework for understanding the nonequilibrium processes,particularly in small systems that are typically far-from-equilibrium and are dominated by thermal or quantum fluctuations.Cavity optomechanical systems hold great promise among the various experimental platforms for studying nonequilibrium thermodynamics owing to their high controllability,excellent mechanical performance,and ability to operate deep in the quantum regime.Here,we present an overview of the recent advances in nonequilibrium thermodynamics with cavity optomechanical systems.The experimental results in entropy production assessment,fluctuation theorems,heat transfer,and heat engines are highlighted.

关键词： Cavity optomechanics Nonequilibrium thermodynamics Stochastic thermodynamics Quantum thermodynamics Entropy production Fluctuation theorems heat transport heat engine

Marine heatwaves in the Gulf of Mexico 1983‒2021: Statistics, recent intensifications, and threats on coral reefs

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气候变化研究进展:英文版 2023年第4期14卷 560-572页

作者： Yu-Ting FENG Brandon JBETHEL Yuan TIAN Chang-Ming DONG Junhong LIANG Yu-Long YAO Jianguo YUAN Ying CHEN Si-Jie CHEN Yang YU Faculty of Chemistry and Environment Science Guangdong Ocean UniversityZhanjiang 524088China Research Center for Coastal Environmental Protection and Ecological Remediation Guangdong Ocean UniversityZhanjiang 524088China Department of Oceanography and Coastal Sciences Louisiana State UniversityLoouisiana 70803USA Small Island Sustainability University of the BahamasNassau N-4912Bahamas Geophysical Institute University of Alaska FairbanksFairbanks 99775USA School of Marine Sciences Nanjing University of Information Science and TechnologyNanjing 210044China Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai) Zhuhai 519000China Center for Computation and Technology Louisiana State UniversityLouisiana 70803USA Coastal Studies Institute Louisiana State UniversityLouisiana 70803USA State Key Laboratory of Tropical Oceanography South China Sea Institute of OceanographyChinese Academy of SciencesGuangzhou 510301China Fujian Meteorological Center Fuzhou 350011China

There is the current lack of comprehensive understanding of the hotspots,frequency,duration,spatiotemporal trends,and physical drivers of marine heatwaves(MHWs)within the Gulf of Mexico(GoM).Here,a series of high-resolution satellite and reanalysis products are used to examine their spatiotemporal characteristics,trends,and possible geophysical triggers of MHWs.Possible impacts of the MHW on coral reefs are also discussed.Results reveal an increasing trend in their frequency,duration,and intensities from 1983–2021,particularly after 2016.It identifies MHWs hotspots within the GoM,notably the northern and western shelves and the Loop Current.The study further documents an intense MHW event from late 2020 to early 2021 near the Yucatan Channel,south of 24°N,attributing its development to oceanic processes such as wind anomalies,anticyclonic eddies,and current-driven heat transport anomalies.The occurrence of this MHW event potentially increased thermal stress on the Campeche and Tuxtlas Reef Systems.This research illuminates the increasing trends and impacts of MHWs in the GoM,providing valuable insights for understanding and predicting the effects of climate change on marine ecosystems.

关键词： Marine heatwaves Gulf of Mexico Coral reef heat transport

The Luzon Strait transport variations during 1997～2000

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Acta Oceanologica Sinica 2004年第1期23卷 83-90页

作者： JIANGTao LIUYun WANGWenzhi KeyLaboratoryofTropicalMarineEnvironmentDynamics SouthChinaSeaInstituteofOceanologyChineseAcademyofSciencesGuangzhou510301China

Based on the output data from 1997 to 2000 obtained by the MITgcm's(general circulation model)adjoint assimilation method, volume, heat and salt transports through the Luzon Strait are calculated. The results indicate that there are obvious different characteristics between 1997 and 1998~2000 on the transports through the Luzon Strait. During 1997, the Luzon Strait had a mean net westward transport of 3.93 ×106 m3/s with a maximum transport of 7.34×106 m3/s in October. During 1998~2000, the Luzon Strait possessed an annual mean eastward transport of 0.93 ×106 , 1.80 ×106 and 1.00 ×106 m3/s respectively with a maximum eastward transport of 4.10 ×106 /3.31 ×106 m3/s in July 1998/ 1999 and 2.06 ×106 m3/s in April 2000, respectively. Moreover, the transports in 1997 indicated a difference from the other years, i.e., that the ranges of westward inflows expanded more obviously to north of the Luzon Strait and downwards exceeding those of the other years. The westward inflows expanded horizontally to the north part of the Luzon Strait until 21o N.

关键词： Luzon Strait volume transport heat transport salt transport

Enhanced mechanical and thermal properties of two-dimensional SiC and GeC with temperature and size dependence

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Chinese Physics B 2023年第7期32卷 101-107页

作者：黄磊任凯张焕萍覃华松 School of Mechanical and Electronic Engineering Nanjing Forestry UniversityNanjing 210037China Laboratory for Multiscale Mechanics and Medical Science SV LABSchool of AerospaceXi’an Jiaotong UniversityXi’an 710049China

Two-dimensional materials with novel mechanical and thermal properties are available for sensors,photodetectors,thermoelectric,crystal diode and flexible nanodevices.In this investigation,the mechanical and thermal properties of pristine SiC and GeC are explored by molecular dynamics simulations.First,the fracture strength and fracture strain behaviors are addressed in the zigzag and armchair directions at 300 K.The excellent toughness of SiC and GeC is demonstrated by the maximal fracture strain of 0.43 and 0.47 in the zigzag direction,respectively.The temperature-tunable tensile strength of SiC and GeC is also investigated.Then,using non-equilibrium molecular dynamics(NEMD)calculations,the thermal performances of SiC and GeC are explored.In particular,the thermal conductivity of SiC and GeC shows a pronounced size dependence and reaches up to 85.67 W·m^(-1)-K^(-1)and 34.37 W·m^(-1)-K^(-1),respectively.The goal of our work is to provide a theoretical framework that can be used in the near future.This will enable us to design an efficient thermal management scheme for two-dimensional materials in electronics and optoelectronics.

关键词： two-dimensional molecular dynamics mechanical property heat transport