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Numerical simulation of formaldehyde distribution characteristics in the high-speed train cabin

Building Simulation 2024年第2期17卷 285-300页

作者： Fan Wu Hang Dong Chao Yu Hengkui Li Qingmin Cui Renze Xu key laboratory of traffic safety on Track Ministry of EducationSchool of Traffic&Transportation EngineeringCentral South UniversityChangshaHunan410075China joint international research laboratory of key technologies for rail traffic safety ChangshaHunan410075China National&Local joint Engineering research Center of safety Technology for rail Vehicle ChangshaHunan410075China School of Software Henan University of EngineeringZhengzhouHenan451191China

The global concern over indoor air pollution in public vehicles has grown significantly.With a focus on enhancing passengers’comfort and health,this study endeavors to investigate the distribution characteristics of formaldehyde within a high-speed train cabin by employing a computational fluid dynamics(CFD)model which is experimentally validated in a real cabin scenario.The research focuses on analyzing the impact of air supply modes,temperature,relative humidity,and fresh air change rate on the distribution and concentration of formaldehyde.The results demonstrate that the difference in average formaldehyde concentration between the two air supply modes is below 1.3%,but the top air supply mode leads to a higher accumulation of formaldehyde near the sidewalls,while the bottom air supply mode promotes a more uniform distribution of formaldehyde.Furthermore,the temperature,relative humidity,and fresh air change rate are the primary factors affecting formaldehyde concentration levels,but they have modest effects on formaldehyde’s distribution pattern within the cabin.As the temperature and relative humidity increase,the changes in formaldehyde concentrations in response to variations in these factors become more evident.Importantly,the formaldehyde concentration may surpass the standard limit of 0.10 mg/m^(3)if the fresh air change rate falls below 212 m^(3)/h.This research provides a systematic approach and referenceable results for exploring formaldehyde pollution in high-speed train cabins.

关键词： indoor air pollution formaldehyde CFD simulation high-speed train ventilation

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Quantitative measurement and application of droplets on physical surfaces based on LIF technology

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Transportation safety and Environment 2024年第2期6卷 104-113页

作者： Fan Wu Shuaixiong Zhou Qingmin Cui Renze Xu Hengkui Li Chao Yu key Labor atory of traffic safety on Track of Ministry of Education School of Traffic&Transportation EngineeringCentr al South Univ ersityChangsha 410075HunanChina joint international research laboratory of key technologies for rail traffic safety School of Traffic&Transportation EngineeringCentral South UniversityChangsha 410075HunanChina School of software Henan University of EngineeringZhengzhou 451191HenanChina National&Local joint Engineering research Center of safety Technology for rail Vehicle School of Traffic&Transportation EngineeringCentral South UniversityChangsha 410075HunanChina

Contaminated surfaces play a significant role in the transmission of respiratory infectious diseases.To address this issue,we pre-sented a novel quantitative detection method for droplets on physical surfaces,based on the laser-induced fluorescence technique.The proposed detection method was demonstrated in a realistic high-speed train compartment scenario by simulating the process of droplet release during passengers’breathing and coughing.The experimental results showed that this method could offer high precision(10-1 mg/m^(2))for detecting minute substance concentrations,and its ease of operation makes it suitable for complex en-gineering environments.The results also revealed that under the combined effects of the indoor airflow and breathing airflow,the range of droplets released by breathing activity exceeded two rows in front of and behind the release position.Simultaneously,we observed that a large number of droplets settled on the seat surfaces on both sides of the same row as the releaser,with over 36%of these droplets concentrated on the backrest area of the seats.As the respiratory jet velocity increased,the location with the most sed-iment droplets(accounting for 8%of the total sedimentation)occurred on the seat directly in front of the releaser,and approximately 48% of the droplets were found on the back of this seat.Our proposed method overcomes the shortcomings of existing experimental methods in quantitatively capturing the motion characteristics of droplets in complex flow fields.

关键词： quantitative measurement sediment droplets physical surfaces fluorescence measurement high-speed train compart-ment

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列车通过分岔隧道的气动效应研究

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Journal of Central South University 2024年第3期31卷 1017-1031页

作者：方丰彦刘堂红夏玉涛许彬王鑫然霍小帅高鸿瑞粱高鹏李文辉 key laboratory of traffic safety on Track of Ministry of Education School of Traffic&Transportation EngineeringCentral South UniversityChangsha 410075China joint international research laboratory of key Technology for rail traffic safety Central South UniversityChangsha 410075China National&Local joint Engineering research Centre of safety Technology for rail Vehicle Central South UniversityChangsha 410075China School of rail Transportation Soochow UniversitySuzhou 215131China

长大铁路隧道受特殊地质条件影响可采用分岔隧道建造。然而,列车高速穿越这种复杂构型的隧道时所引起的空气动力学效应尚不清楚。为此,本文采用三维、可压缩、非定常的雷诺时均模型,模拟研究了高速列车从不同方向通过分岔隧道时引起的... 详细信息

长大铁路隧道受特殊地质条件影响可采用分岔隧道建造。然而,列车高速穿越这种复杂构型的隧道时所引起的空气动力学效应尚不清楚。为此,本文采用三维、可压缩、非定常的雷诺时均模型,模拟研究了高速列车从不同方向通过分岔隧道时引起的气动效应。研究内容主要包括入口隧道结构为单线隧道(STE)和双线隧道(DTE)两个运行环境下的车体表面和隧道壁面的压力波动、列车气动力和周围流场特征等。研究结果表明,相比STE场景,DTE场景下车体表面和单线隧道壁面的压力峰峰值更大,并且气动阻力能耗也更大,头车的平均阻力增大19.2%。然而,STE场景下列车的侧向力波动更剧烈,其峰值相比DTE场景增加26%。本文的研究发现可为特殊铁路隧道的设计和建造提供有价值的空气动力学参考。

关键词：高速列车分岔隧道瞬态压力波气动力

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Flexible pressure sensors with ultrahigh stress tolerance enabled by periodic microslits

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Microsystems & Nanoengineering 2024年第1期10卷 301-311页

作者： Song Wang Chenying Wang Yifan Zhao Yujing Zhang Yaxin Zhang Xiangyue Xu Qijing Lin Kai Yao Yuheng Wang Feng Han Yu Sun Zhuangde Jiang State key laboratory for Manufacturing Systems Engineering International Joint Laboratory for Micro/Nano Manufacturing and Measurement TechnologiesSchool of Mechanical EngineeringXi’an Jiaotong UniversityXi’anChina State key laboratory for Manufacturing Systems Engineering International Joint Laboratory for Micro/Nano Manufacturing and Measurement TechnologiesSchool of Instrument Science and TechnologyXi’an Jiaotong UniversityXi’anChina The Faculty of Electrical Engineering and Computer Science Ningbo UniversityNingboChina Department of Mechanical and Industrial Engineering University of TorontoTorontoCanada

Stress tolerance plays a vital role in ensuring the effectiveness of piezoresistive sensing films used in flexible pressure sensors.However,existing methods for enhancing stress tolerance employ dome-shaped,wrinkle-shaped,and pyramidal-shaped microstructures in intricate molding and demolding processes,which introduce significant fabrication challenges and limit the sensing performance.To address these shortcomings,this paper presents periodic microslits in a sensing film made of multiwalled carbon nanotubes and polydimethylsiloxane to realize ultrahigh stress tolerance with a theoretical maximum of 2.477 MPa and a sensitivity of 18.092 kPa−1.The periodic microslits permit extensive deformation under high pressure(e.g.,400 kPa)to widen the detection range.Moreover,the periodic microslits also enhance the sensitivity based on simultaneously exhibiting multiple synapses within the sensing interface and between the periodic sensing cells.The proposed solution is verified by experiments using sensors based on the microslit strategy for wind direction detection,robot movement sensing,and human health monitoring.In these experiments,vehicle load detection is achieved for ultrahigh pressure sensing under an ultrahigh pressure of over 400 kPa and a ratio of the contact area to the total area of 32.74%.The results indicate that the proposed microslit strategy can achieve ultrahigh stress tolerance while simplifying the fabrication complexity of preparing microstructure sensing films.

关键词： robot shaped stress

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Congener-derived template to construct lithiophilic organic-inorganic layer/interphase for high volumetric capacity dendrite-free Li metal batteries

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Chinese Chemical Letters 2024年第3期35卷 453-460页

作者： Kang Yang Long Li Yuanbin Xiao Qiaoli Zhang Chenpeng Xi Borong Li Yan Yu Chengkai Yang key laboratory of Advanced Materials technologies International(HongKong Macao and Taiwan)Joint Laboratory on Advanced Materials TechnologiesCollege of Materials Science and EngineeringFuzhou UniversityFuzhou 350108China

The development of lithium-metal batteries(LMBs)is seriously restricted by the out-of-control dendrites growth and infinite volume expansion.Herein,a pervasive organic-inorganic layer construction strategy is reported for the composite lithium metal anode with congener-derived organic-inorganic solid electrolyte interphase(SEI).In this strategy,the organic-inorganic Ag@polydopamine(Ag@PDA)layer is coated on the arbitrary substrates by a simple two-step method.The thin and stable congener-derived SEI is insitu formed with fewer inorganic components and more organic components during charging/discharging.The polydopamine with sufficient adhesion groups and lithiophilic Ag layer realize near-zero nucleation overpotential during lithium deposition.The low interface resistance and stable lithium deposition are achieved.Moreover,the practical areal and volumetric capacities of the composite anode with three-dimensional copper(3DCu)as the substrate are 10 mAh/cm^(2)and 1538 mAh/cm^3(vs.the mass of anode).The symmetrical cell shows very low polarization voltage(10 mV)and more than 2500 h cycles life at 1 mA/cm^(2)(1 mAh/cm^(2)).The LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2)(NCM811)-based full cells show improved capacity retention(82%)after 100 cycles at 0.5 C.The modified lithiophilic anode with congener-derived interphase provides a promising strategy to realize the next-generation dendrite-free LMBs.

关键词： Lithium metal anode Congener-derived Lithiophilicity Volumetric capacity Organic-inorganic interphase

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Combined effect of WS2 and Ti3C2Tx MXene favors oil-based ultra-low friction on rough steel-steel interface at elevated temperatures

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Science China Technological Sciences 2024年第7期67卷 1991-2002页

作者： LIU YangQin CHEN Lei WANG Yang QIAN LinMao Tribology research Institute State Key Laboratory of Rail Transit Vehicle System School of Mechanical EngineeringSouthwest Jiaotong University key laboratory of Advanced technologies of Materials (Ministry of Education) Research Institute of Frontier ScienceSouthwest Jiaotong University

The lubrication performance of liquids is severely restricted and is degraded in high-temperature environments. Stable and reliable lubrication in high temperature environments has been a long-standing goal in various industrial fields. In this study,WS2and Ti3C2TxMXene nanoflakes were used as oil-based lubricant additives to generate ultra-low friction and even superlubricity（friction coefficient of ～0.007） at elevated temperatures（400°C）, which has hitherto not been achieved by both individual pristine materials, WS2and Ti3C2TxMXene. Viscosity and thermogravimetric characterization revealed improvements in the high-temperature rheological properties and thermal stability of the lubricating base oil, indicating improved loadbearing and continuous lubrication capabilities at elevated temperatures. X-ray photoelectron spectroscopy, transmission electron microscopy, and atomic force microscopy demonstrated that the formation of an iron/titanium/tungsten-rich oxide lubricious thin film at the sliding interface reduced the interfacial shear stress, which was responsible for the observed friction and wear reductions at high contact pressures（> 1.1 GPa）. Although the titanium/tungsten oxide film was gradually removed after prolonged sliding, a sufficiently thick iron oxide film maintained a low friction coefficient for at least 2 h. The improved surface quality facilitates the achievement of ultra-low friction and reduced wear. The proposed lubrication methodology has a broad utilization potential as a wear-reduction strategy across various industrial fields at elevated temperatures.

关键词： ultra-low friction high-temperature wear reduction lubricating additive tungsten disulfide MXene

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Remote copper-catalyzed enantioselective substitution of yne-thiophene carbonates

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Science China Chemistry 2024年第4期67卷 1175-1180页

作者： Hao-Dong Qian Xiang Li Tingrui Yin Wei-Feng Qian Chunhui Zhao Cuiju Zhu Hao Xu CCNU-uOttawa joint research Centre Key Laboratory of Pesticides&Chemical Biology of Ministry of EducationInternational Joint Research Center for Intelligent Biosensing Technology and HealthCollege of ChemistryCentral China Normal UniversityWuhan 430079China

Here,we describe a strategy for the copper-catalyzed asymmetric heteroarylation of yne-thiophene carbonates with indoles via remote substitution.The key to the success of this strategy lies in the design of the alkynyl group at the ortho-position of the heterocycle thiophene,enabling the formation of a triarylmethane moiety via very remote substitution.Thus,the concept of remote copper-catalyzed asymmetric transformation extends not only to yne-allylic esters but also to yne-aryl esters.The reaction readily provides a diverse array of chiral triarylmethanes with high efficiency,enantioselectivity,and excellent functional group compatibility.Moreover,facile follow-up transformations underscore their potential utility in the synthesis of various enantioenriched building blocks.Preliminary mechanistic studies support the plausibility of the remote substitution pathway.

关键词： remote substitution copper catalyst asymmetric catalysis triaryl methanes

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Molecule configurations modulate packing array and charge transfer in cocrystal engineering

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Science China Chemistry 2024年第2期67卷 512-516页

作者： Shenglong An Mengyuan Qiao Xin Jin Xuanying Chen Jianhua Su Lifang Guo Zhiyun Zhang key laboratory for Advanced Materials and joint international research laboratory of Precision Chemistry and Molecular Engineering Feringa Nobel Prize Scientist Joint Research CentreFrontiers Science Center for Materiobiology and Dynamic ChemistryEast China University of Science&TechnologyShanghai200237China

Organic cocrystal as an emerging assembly strategy has received increasing attention in constructing multiple functional materials,through continually screening suitable constituent monomers or changing their stoichiometry ratios.However,the role of molecule configuration in the cocrystal field is rarely explored despite the fascinating potential in regulating the packing mode.In this study,the N,N′-diphenyl-5,10-dihydrophenazine derivatives(DPPs) with the flexible scaffold and different methyl substitutions are selected as the donors bearing various molecular configurations.In a simple collaborative way,a series of cocrystals based on DPPs and OFN(octafluoronaphthalene) are fabricated,exhibiting two self-adaptive molecular stacking arrays.X-ray crystallographic analysis and theoretical calculation unveil their different π···π interactions and charge transfer characters,leading to the significant emission redshift up to 125 nm compared with individual DPPs.As a result,controllable molecule stacking structure,tunable emission,and charge transfer properties can be achieved.The study provides a new perspective to reveal the structure-property relationships at the molecular level by controlling the molecule configuration in cocrystal engineering,contributing to the development of cocrystal theoretical physics and organic functional materials.

关键词： cocrystals molecular configuration self-adaptive packing mode charge transfer

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Error field penetration in J-TEXT tokamak based on two-fluid drift-MHD model

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Chinese Physics B 2024年第4期33卷 545-551页

作者：王文徐涛张仪 the J-TEXT team State key laboratory of Advanced Electromagnetic Technology International Joint Research Laboratory of Magnetic Confinement Fusion and Plasma PhysicsSchool of Electrical and Electronic EngineeringHuazhong University of Science and TechnologyWuhan 430074China

An externally generated resonant magnetic perturbation can induce complex non-ideal MHD responses in their resonant surfaces.We have studied the plasma responses using Fitzpatrick's improved two-fluid model and program LAYER.We calculated the error field penetration threshold for J-TEXT.In addition,we find that the island width increases slightly as the error field amplitude increases when the error field amplitude is below the critical penetration value.However,the island width suddenly jumps to a large value because the shielding effect of the plasma against the error field disappears after the penetration.By scanning the natural mode frequency,we find that the shielding effect of the plasma decreases as the natural mode frequency decreases.Finally,we obtain the m/n=2/1 penetration threshold scaling on density and temperature.

关键词： plasma responses drift-MHD model error field penetration

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A new review of single-ion conducting polymer electrolytes in the light of ion transport mechanisms

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Journal of Energy Chemistry 2024年第2期89卷 543-556,I0012页

作者： Yuqi Luo Lu Gao Weimin Kang State key laboratory of Separation Membranes and Membrane Processes/National Center for international joint research on Separation Membranes School of Textile Science and EngineeringTiangong UniversityTianjin 300387China

With the depletion of fossil fuels and the demand for high-performance energy storage devices,solidstate lithium metal batteries have received widespread attention due to their high energy density and safety advantages.Among them,the earliest developed organic solid-state polymer electrolyte has a promising future due to its advantages such as good mechanical flexibility,but its poor ion transport performance dramatically limits its performance improvement.Therefore,single-ion conducting polymer electrolytes(SICPEs)with high lithium-ion transport number,capable of improving the concentration polarization and inhibiting the growth of lithium dendrites,have been proposed,which provide a new direction for the further development of high-performance organic polymer electrolytes.In view of this,lithium ions transport mechanisms and design principles in SICPEs are summarized and discussed in this paper.The modification principles currently used can be categorized into the following three types:enhancement of lithium salt anion-polymer interactions,weakening of lithium salt anion-cation interactions,and modulation of lithium ion-polymer interactions.In addition,the advances in single-ion conductors of conventional and novel polymer electrolytes are summarized,and several typical highperformance single-ion conductors are enumerated and analyzed in what way they improve ionic conductivity,lithium ions mobility,and the ability to inhibit lithium dendrites.Finally,the advantages and design methodology of SICPEs are summarized again and the future directions are outlined.

关键词： Lithium metal batteries Single-ion conductor Polymer electrolytes Ion transport mechanism Li-ion transport number

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