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Future urban transport management

《工程管理前沿（英文）》   页码 534-539 doi: 10.1007/s42524-023-0255-3

摘要： The incorporation of disruptive innovations into the transportation industry will inevitably cause major upheavals in the transportation sector. However, existing research lacks systematic theories and methodologies to represent the underlying characteristics of future urban transport systems. Furthermore, emerging modes in urban mobility have not been sufficiently studied. The National Natural Science Foundation of China (NSFC) officially approved the Basic Science Center project titled “Future Urban Transport Management” in 2022. The project members include leading scientists and engineers from Beijing Jiaotong University, Beihang University, and Beijing Transport Institute. Based on a wide range of previous projects by the consortium on urban mobility and sustainable cities, this project will encompass transdisciplinary and interdisciplinary research to explore critical issues affecting future urban traffic management. It aims to develop fundamental theories and methods based on social and technological developments in the near future and explores innovative solutions to implement alongside these emerging developments in urban mobility.

关键词： future urban transport management     travel behavior characteristics     transportation operations     transportation emergency management     transportation decision intelligence    

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Exploration of the oxygen transport behavior in non-precious metal catalyst-based cathode catalyst layer

Shiqu CHEN, Silei XIANG, Zehao TAN, Huiyuan LI, Xiaohui YAN, Jiewei YIN, Shuiyun SHEN, Junliang ZHANG

《能源前沿（英文）》 2023年 第17卷 第1期   页码 123-133 doi: 10.1007/s11708-022-0849-1

摘要： High cost has undoubtedly become the biggest obstacle to the commercialization of proton exchange membrane fuel cells (PEMFCs), in which Pt-based catalysts employed in the cathodic catalyst layer (CCL) account for the major portion of the cost. Although non-precious metal catalysts (NPMCs) show appreciable activity and stability in the oxygen reduction reaction (ORR), the performance of fuel cells based on NPMCs remains unsatisfactory compared to those using Pt-based CCL. Therefore, most studies on NPMC-based fuel cells focus on developing highly active catalysts rather than facilitating oxygen transport. In this work, the oxygen transport behavior in CCLs based on highly active Fe-N-C catalysts is comprehensively explored through the elaborate design of two types of membrane electrode structures, one containing low-Pt-based CCL and NPMC-based dummy catalyst layer (DCL) and the other containing only the NPMC-based CCL. Using Zn-N-C based DCLs of different thickness, the bulk oxygen transport resistance at the unit thickness in NPMC-based CCL was quantified via the limiting current method combined with linear fitting analysis. Then, the local and bulk resistances in NPMC-based CCLs were quantified via the limiting current method and scanning electron microscopy, respectively. Results show that the ratios of local and bulk oxygen transport resistances in NPMC-based CCL are 80% and 20%, respectively, and that an enhancement of local oxygen transport is critical to greatly improve the performance of NPMC-based PEMFCs. Furthermore, the activity of active sites per unit in NPMC-based CCLs was determined to be lower than that in the Pt-based CCL, thus explaining worse cell performance of NPMC-based membrane electrode assemblys (MEAs). It is believed that the development of NPMC-based PEMFCs should proceed not only through the design of catalysts with higher activity but also through the improvement of oxygen transport in the CCL.

关键词： proton exchange membrane fuel cells (PEMFCs)     non-precious metal catalyst (NPMC)     cathode catalyst layer (CCL)     local and bulk oxygen transport resistance    

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Degradation of permeability resistance of high strength concrete after combustion

LI Min, QIAN Chunxiang, KAO Hongtao

《结构与土木工程前沿（英文）》 2008年 第2卷 第3期   页码 281-287 doi: 10.1007/s11709-008-0031-9

摘要： To evaluate the remaining durability of concrete materials after combustion, the permeability of high strength concrete (HSC) after combustion was studied. The transport behavior of chloride ion, water and air in concrete after combustion and the effect of temperature, strength grade, and aggregation on the permeability of HSC after combustion are investigated by chloride ion permeability coefficient (), water permeability coefficient () and air permeability coefficient (). The experiment results show that all three permeability coefficients commendably reflect changes of permeability. The permeability coefficient increases with the evaluation temperature. After the same temperature, the permeability coefficient of HSC is lower than that of normal strength concrete (NSC). However, the degree of degradation of permeability coefficient of HSC is greater than that of NSC. The permeability resistance of HSC containing limestone is better than that of HSC containing basalt. Combining changes of compressive strength and permeability, the remaining durability of concrete materials after combustion is appropriately evaluated.

关键词： transport behavior     limestone     durability     permeability     HSC    

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The source and transport of bioaerosols in the air: A review

《环境科学与工程前沿（英文）》 2021年 第15卷 第3期 doi: 10.1007/s11783-020-1336-8

摘要：

• Emission of microbe from local environments is a main source of bioaerosols.

关键词： Bioaerosols     Diffusion     Source identification     Biogeography    

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Intercontinental transport of air pollution

Lin ZHANG,

《环境科学与工程前沿（英文）》 2010年 第4卷 第1期   页码 20-29 doi: 10.1007/s11783-010-0014-7

摘要： There is an increasing interest on the intercontinental transport of air pollution among the three main emission regions at northern mid-latitudes: North America, Europe, and East Asia. Air pollutants with sufficient long lifetime can be transported from one continent to another. Observations from ground sites, aircraft and satellites have demonstrated this intercontinental-scale transport of air pollutants in the free troposphere. Numerical models have been applied to understand the pathways of the transport and the impact of intercontinental pollution transport. This paper reviews current observational evidence and modeling studies of intercontinental transport of ozone and its precursors, and the resulting impacts on air quality.

关键词： intercontinental transport     ozone     air pollution    

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Thermal transport properties of monolayer phosphorene: a mini-review of theoretical studies

Guangzhao QIN, Ming HU

《能源前沿（英文）》 2018年 第12卷 第1期   页码 87-96 doi: 10.1007/s11708-018-0513-y

摘要： Phosphorene, a two-dimensional (2D) elemental semiconductor with a high carrier mobility and intrinsic direct band gap, possesses fascinating chemical and physical properties distinctively different from other 2D materials. Its rapidly growing applications in nano-/opto-electronics and thermoelectrics call for fundamental understanding of the thermal transport properties. Considering the fact that there have been so many studies on the thermal transport in phosphorene, it is on emerging demand to have a review on the progress of previous studies and give an outlook on future work. In this mini-review, the unique thermal transport properties of phosphorene induced by the hinge-like structure are examined. There exists a huge deviation in the reported thermal conductivity of phosphorene in literature. Besides, the mechanism underlying the deviation is discussed by reviewing the effect of different functionals and cutoff distance in calculating the thermal transport properties of phosphorene. It is found that the (vdW) interactions play a key role in the formation of resonant bonding, which leads to long-ranged interactions. Taking into account of the vdW interactions and including the long-ranged interactions caused by the resonant bonding with large cutoff distance are important for getting the accurate and converged thermal conductivity of phosphorene. Moreover, a fundamental insight into the thermal transport is provided based on the review of resonant bonding in phosphorene. This mini-review summarizes the progress of the thermal transport in phosphorene and gives an outlook on future horizons, which would benefit the design of phosphorene based nano-electronics.

关键词： thermal transport     phosphorene     resonant bonding    

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EFFECTS OF TRANSPORT STRESS ON THE INTESTINES INVOLVING NEURONAL NITRIC OXIDE SYNTHASE

《农业科学与工程前沿（英文）》   页码 285-295 doi: 10.15302/J-FASE-2022469

摘要：

● Transport stress declined the level of leukocytes including lymphocytes in rat serum.

关键词： intestine     nNOS     nNOS-positive neurons     transport stress    

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Cooling strategies and transport theories for brain hypothermia resuscitation

LIU Jing

《能源前沿（英文）》 2007年 第1卷 第1期   页码 32-57 doi: 10.1007/s11708-007-0004-z

摘要： The brain is one of the most important organs in a biological body whose normal function depends heavily on an uninterrupted delivery of oxygen. Unlike skeletal muscles that can survive for hours without oxygen, neuron cells in the brain are easily subjected to an irreversible damage within minutes from the onset of oxygen deficiency. With the interruption of cardiopulmonary circulation in many cardiac surgical procedures or accidental events leading to cerebral circulation arrest, an imbalance between energy production and consumption will occur which causes a rapid depletion of oxygen due to the interrupted blood-flow to the brain. Meanwhile, the cooling function of the blood flow on the hot tissue will be stopped, while metabolic heat generation in the tissues still keeps running for awhile. Under such adverse situations, the potential for cerebral protection through hypothermia has been intensively investigated in clinics by lowering brain temperature to restrain the cerebral oxygen demands. The reason can be attributed to the decreased metabolic requirements of the cold brain tissues, which allows a longer duration for the brain to endure reduced oxygen delivery. It is now clear that hypothermia would serve as the principal way for neurologic protection in a wide variety of emergency medicines, especially in cerebral damage, anoxia, circulatory arrest, respiratory occlusion, etc. However, although brain cooling has been found uniquely significant in clinical practices, the serious lack of knowledge on the mechanisms involved prevents its further advancement in brain resuscitation. Compared with the expanded trials in clinics, only very limited efforts were made to probe the engineering issues involved, which turns out to be a major obstacle for the successful operation of brain hypothermia resuscitation. From the viewpoint of biothermal medical engineering, the major theories and strategies for administering brain cooling can generally be classified into three categories: heat transfer, oxygen transport and cooling strategy. Aiming to provide a complete overview of the brain hypothermia resuscitation, this article comprehensively summarizes the recent progresses made in theoretical, practical and experimental techniques in the area. Particularly, attention is paid to the mathematical models to quantify the heat and oxygen transport inside the cerebral tissues. Typical cooling strategies to effectively lower brain temperature and thus decrease oxygen consumption rate in the cerebral tissues are analyzed. Approaches to deliver oxygen directly to the target tissues are discussed. Meanwhile, some future efforts worth pursuing within the area of brain cooling are suggested.

关键词： mathematical     interruption     hypothermia     metabolic     generation    

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Seasonal variations of transport pathways andpotential sources of PM

Yuan Chen, Shaodong Xie, Bin Luo

《环境科学与工程前沿（英文）》 2018年 第12卷 第1期 doi: 10.1007/s11783-018-1009-z

摘要： Seasonal pattern of transport pathways and potential sourcesof PM in Chengdu during 2012–2013were investigated based on hourly PM data,backward trajectories, clustering analysis, potential source contributionfunction (PSCF), and concentration-weighted trajectory (CWT) method.The annual hourly mean PM concentrationin Chengdu was 97.4 mg·m . 5, 5, 5 and 3 mean clusters were generatedin four seasons, respectively. Short-distance air masses, which travelledwithin the Sichuan Basin with no specific source direction and relativelyhigh PM loadings (>80 mg·m ) appearedas important pathways in all seasons. These short pathways indicatedthat emissions from both local and surrounding regions of Chengducontributed significantly to PM pollution.The cities in southern Chengdu were major potential sources with PSCF>0.6and CWT>90 mg·m . The northeastern pathway prevailed throughoutthe year with higher frequency in autumn and winter and lower frequencyin spring and summer. In spring, long-range transport from southernXinjiang was a representative dust invasion path to Chengdu, and theCWT values along the path were 30-60 mg·m . Long-range transportwas also observed in autumn from southeastern Xinjiang along a northwesterlypathway, and in winter from the Tibetan Plateau along a westerly pathway.In summer, the potential source regions of Chengdu were smaller thanthose in other seasons, and no long-range transport pathway was observed.Results of PSCF and CWT indicated that regions in Qinghai and Tibetcontributed to PM pollution in Chengdu aswell, and their CWT values increased to above 30 mg·m in winter.

关键词： Transport pathway     Backwardtrajectory     Clustering analysis     Potential source     Chengdu    

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A CFD study of the transport and fate of airborne droplets in a ventilated office: The role of droplet

《环境科学与工程前沿（英文）》 2022年 第16卷 第3期 doi: 10.1007/s11783-021-1465-8

摘要：

• Coulomb and Lennard−Jones forces were considered for droplet interactions.

关键词： Droplet interactions     Aerosols     Colloids     CFD     Transport     Fate    

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Computational fluid dynamics simulation of aerosol transport and deposition

Yingjie TANG, Bing GUO

《环境科学与工程前沿（英文）》 2011年 第5卷 第3期   页码 362-377 doi: 10.1007/s11783-011-0365-8

摘要： In this article computational fluid dynamics (CFD) simulation of aerosol transport and deposition, i.e. the transport and deposition of particles in an aerosol, is reviewed. The review gives a brief account of the basics of aerosol mechanics, followed by a description of the general CFD approach for flow field simulation, turbulence modeling, wall treatments and simulation of particle motion and deposition. Then examples from the literature are presented, including CFD simulation of particle deposition in human respiratory tract and particle deposition in aerosol devices. CFD simulation of particle transport and deposition may provide information that is difficult to obtain through physical experiments, and it may help reduce the number of experiments needed for device design. Due to the difficulty of describing turbulent flow and particle-eddy interaction, turbulent dispersion of particles remains one of the greatest challenges for CFD simulation. However, it is possible to take a balanced approach toward quantitative description of aerosol dispersion using CFD simulation in conjunction with empirical relations.

关键词： computational fluid dynamics (CFD)     aerosol     transport     deposition    

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Mass transport mechanisms within pervaporation membranes

Yimeng Song, Fusheng Pan, Ying Li, Kaidong Quan, Zhongyi Jiang

《化学科学与工程前沿（英文）》 2019年 第13卷 第3期   页码 458-474 doi: 10.1007/s11705-018-1780-1

摘要： Pervaporation is an energy-efficient membrane technology for separating liquid molecules of similar physical properties, which may compete or combine with distillation separation technology in a number of applications. With the rapid development of new membrane materials, the pervaporation performance was significantly improved. Fundamental understanding of the mass transport mechanisms is crucial for the rational design of membrane materials and efficient intensification of pervaporation process. Based on the interactions between permeate molecules and membranes, this review focuses on two categories of mass transport mechanisms within pervaporation membranes: physical mechanism (solution-diffusion mechanism, molecular sieving mechanism) and chemical mechanism (facilitated transport mechanism). Furthermore, the optimal integration and evolution of different mass transport mechanisms are briefly introduced. Material selection and relevant applications are highlighted under the guidance of mass transport mechanisms. Finally, the current challenges and future perspectives are tentatively identified.

关键词： pervaporation membrane     mass transport mechanisms     physical mechanism     chemical mechanism    

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Analytical solutions of three-dimensional contaminant transport in uniform flow field in porous media

Hongtao WANG, Huayong WU

《环境科学与工程前沿（英文）》 2009年 第3卷 第1期   页码 112-128 doi: 10.1007/s11783-008-0067-z

摘要： The purpose of this study is to present a library of analytical solutions for the three-dimensional contaminant transport in uniform flow field in porous media with the first-order decay, linear sorption, and zero-order production. The library is constructed using Green's function method (GFM) in combination with available solutions. The library covers a wide range of solutions for various conditions. The aquifer can be vertically finite, semi-infinitive or infinitive, and laterally semi-infinitive or infinitive. The geometry of the sources can be of point, line, plane or volumetric body; and the source release can be continuous, instantaneous, or by following a given function over time. Dimensionless forms of the solutions are also proposed. A computer code FlowCAS is developed to calculate the solutions. Calculated results demonstrate the correctness of the presented solutions. The library is widely applicable to solve contaminant transport problems of one- or multiple- dimensions in uniform flow fields.

关键词： solution library     contaminant transport     analytical solution     dispersion and advection     porous media     type curve     Green's function method (GFM)    

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Numerical simulation of benzene transport in shoreline groundwater affected by tides under different

《环境科学与工程前沿（英文）》 2022年 第16卷 第5期 doi: 10.1007/s11783-022-1540-9

摘要：

● An approach for assessing the transport of benzene on the beach was proposed.

关键词： Numerical simulation     Benzene     Transport and fate     Shoreline     Groundwater     Tide    

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Thermo-fluidic devices and materials inspired from mass and energy transport phenomena in biological

Jian XIAO , Jing LIU ,

《能源前沿（英文）》 2009年 第3卷 第1期   页码 47-59 doi: 10.1007/s11708-008-0068-4

摘要： Mass and energy transport consists of one of the most significant physiological processes in nature, which guarantees many amazing biological phenomena and activities. Borrowing such idea, many state-of-the-art thermo-fluidic devices and materials such as artificial kidneys, carrier erythrocyte, blood substitutes and so on have been successfully invented. Besides, new emerging technologies are still being developed. This paper is dedicated to presenting a relatively complete review of the typical devices and materials in clinical use inspired by biological mass and energy transport mechanisms. Particularly, these artificial thermo-fluidic devices and materials will be categorized into organ transplantation, drug delivery, nutrient transport, micro operation, and power supply. Potential approaches for innovating conventional technologies were discussed, corresponding biological phenomena and physical mechanisms were interpreted, future promising mass-and-energy-transport-based bionic devices were suggested, and prospects along this direction were pointed out. It is expected that many artificial devices based on biological mass and energy transport principle will appear to better improve various fields related to human life in the near future.

关键词： bionics     mass transport     energy transport     artificial devices and materials     biology system     nature phenomena     medical device.    

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标题 作者 时间 类型 操作

Future urban transport management

期刊论文

Exploration of the oxygen transport behavior in non-precious metal catalyst-based cathode catalyst layer

Shiqu CHEN, Silei XIANG, Zehao TAN, Huiyuan LI, Xiaohui YAN, Jiewei YIN, Shuiyun SHEN, Junliang ZHANG

期刊论文

Degradation of permeability resistance of high strength concrete after combustion

LI Min, QIAN Chunxiang, KAO Hongtao

期刊论文

The source and transport of bioaerosols in the air: A review

期刊论文

Intercontinental transport of air pollution

Lin ZHANG,

期刊论文

Thermal transport properties of monolayer phosphorene: a mini-review of theoretical studies

Guangzhao QIN, Ming HU

期刊论文

EFFECTS OF TRANSPORT STRESS ON THE INTESTINES INVOLVING NEURONAL NITRIC OXIDE SYNTHASE

期刊论文

Cooling strategies and transport theories for brain hypothermia resuscitation

LIU Jing

期刊论文

Seasonal variations of transport pathways andpotential sources of PM

Yuan Chen, Shaodong Xie, Bin Luo

期刊论文

A CFD study of the transport and fate of airborne droplets in a ventilated office: The role of droplet

期刊论文

Computational fluid dynamics simulation of aerosol transport and deposition

Yingjie TANG, Bing GUO

期刊论文

Mass transport mechanisms within pervaporation membranes

Yimeng Song, Fusheng Pan, Ying Li, Kaidong Quan, Zhongyi Jiang

期刊论文

Analytical solutions of three-dimensional contaminant transport in uniform flow field in porous media

Hongtao WANG, Huayong WU

期刊论文

Numerical simulation of benzene transport in shoreline groundwater affected by tides under different

期刊论文

Thermo-fluidic devices and materials inspired from mass and energy transport phenomena in biological

Jian XIAO , Jing LIU ,

期刊论文