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The recirculation flow after different cross-section shaped high-rise buildings with applications to ventilation assessment and drag parameterization

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Building Simulation 2024年第4期17卷 509-524页

作者： Keyi Chen Ziwei Mo jian hang School of Atmospheric Sciences Sun Yat-sen University&Southern Marine Science and Engineering Guangdong LaboratoryZhuhai519082China Key Laboratory of Tropical Atmosphere-Ocean System Ministry of EducationZhuhai519000China

The building cross-section shape significantly affects the flow characteristics around buildings,especially the recirculation region behind the high-rise *** generic building shapes including square,triangle,octagon,T-shaped,cross-shaped,#-shaped,H-shaped and L-shaped are examined to elucidate their effects on the flow patterns,recirculation length L and areas A using computational fluid dynamics(CFD)simulations with Reynolds-averaged Navier-Stokes(RANS)*** sizes and positions of the vortexes behind the buildings are found to be substantially affected by the building shapes and subsequently changing the recirculation *** recirculation length L is in the range of 1.6b-2.6b with an average of *** maximum L is found for L-shaped building(2.6b)while the shortest behind octagon building(1.6b).The vertical recirculation area Av is in the range of 1.5b^(2)-3.2b^(2)and horizontal area Ah in 0.9b^(2)-2.2b^(2).The L,Av and Ah generally increase with increasing approaching frontal area when the wind direction changes but subject to the dent structures of the#-shaped and cross-shaped *** area-averaged wind velocity ratio(AVR),which is proposed to assess the ventilation performance,is in the range of 0.05 and 0.14,which is around a three-fold difference among the different building *** drag coefficient parameterized by Ah varies significantly,suggesting that previous models without accounting for building shape effect could result in large uncertainty in the drag *** findings provide important reference for improving pedestrian wind environment and shed some light on refining the urban canopy parameterization by considering the building shape effect.

关键词： recirculation region cross-section shape ventilation assessment drag parameterization computational fluid dynamics

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Predominance of inhalation route in short-range transmission of respiratory viruses:Investigation based on computational fluid dynamics

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Building Simulation 2023年第5期16卷 765-780页

作者： Wenzhao Chen Li Liu jian hang Yuguo Li Department of Mechanical Engineering The University of Hong KongPokfulam RoadHong KongChina Department of Building Science Tsinghua UniversityBeijing 100084China School of Atmospheric Sciences Sun Yat-sen Universityand Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai)Zhuhai 519082China Faculty of Architecture The University of Hong KongPokfulam RoadHong KongChina

During the coronavirus disease 2019 pandemic,short-range virus transmission has been observed to have a higher risk of causing infection than long-range virus ***,the roles played by the inhalation and large droplet routes cannot be distinguished in practice.A recent analytical study revealed the predominance of short-range inhalation over the large droplet spray route as causes of respiratory *** the current study,short-range exposure was analyzed via computational fluid dynamics(CFD)simulations using a discrete phase *** facial membranes,including eyes,nostrils,and a mouth,were *** CFD simulations,there is no need for a spherical approximation of the human head for estimating deposition nor the“anisokinetic aerosol sampling”approximation for estimating inhalation in the analytical *** considered two scenarios(with two spheres[Scenario 1]and two human manikins[Scenario 2]),source-target distances of 0.2 to 2 m,and droplet diameters of 3 to 1,500μ*** overall CFD exposure results agree well with data previously obtained from a simple analytical *** CFD results confirm the predominance of the short-range inhalation route beyond 0.2 m for expiratory droplets smaller than 50μm during talking and coughing.A critical droplet size of 87.5μm was found to differentiate droplet *** number of droplets deposited on the target head exceeded those exposed to facial membranes,which implies a risk of exposure through the immediate surface route over a short range.

关键词： airborne transmission close contact short-range inhalation large droplet spray computational fluid dynamics

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Smelting Oxidation Desulfurization of Copper Slags

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Journal of Iron and Steel Research International 2012年第12期19卷 14-20页

作者： LI Lei HU jian-hang WANG Hua Engineering Research Center of Metallurgical Energy Conservation and Emission Reduction of Ministry ofEducation Faculty of Metallurgical and Energy Engineering Kunming University of Science and TechnologyKunming 650093 Yunnan China

According to the mechanism of sulfur removal easily through oxidation, the process of smelting oxidation desulfurization of copper slags is studied, which supplies a new thinking for obtaining the molten iron of lower sulfur content by smelting reduction of copper slags. Special attention is given to the effects of the holding temperature, the holding time and CaF2, CaO addition amounts on the desulfurization rate of copper slags. The results indicate that the rate of copper slags smelting oxidation desulfurization depends on the matte mass transfer rate through the slag phase. After the oxidation treatment, sulfur of copper slags can be removed as SO2 efficiently. Amount of Ca2＋ of copper slags affects the desulfurization rate greatly, and the slag desulfurization rate is reduced by adding a certain amount of CaF2 and CaO. Compared with CaF2, CaO is negative to slags sulfur removal with equal Ca2＋ addition. Under the air flow of 0.3 U/min, the sulfur content of copper slags can be reduced to 0. 004 67% in the condition of the holding time of 3 min and the holding temperature of 1 500 ℃. The sulfur content of molten iron is reduced to 0. 000 8 % in the smelting reduction of treated slags, and the problem of high sulfur content of molten iron obtained by smelting reduction with copper slag has been successively solved.

关键词： copper slag smelting oxidation desulfurization additive gas-liquid reaction

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Possible high COVID-19 airborne infection risk in deep and poorly ventilated 2D street canyons

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Building Simulation 2023年第9期16卷 1617-1628页

作者： Vitor Lavor Omduth Coceal Sue Grimmond jian hang Zhiwen Luo School of the Built Environment University of ReadingReadingUK Department of Meteorology University of ReadingReadingUK School of Atmospheric Sciences Guangdong Province Key Laboratory for Climate Change and Natural Disaster StudiesSun Yat-sen UniversityGuangzhouChina Welsh School of Architecture Cardiff UniversityCardiffUK

Despite the widespread assumption that outdoor environments provide sufficient ventilation and dilution capacity to mitigate the risk of COVID-19 infection,there is little understanding of airborne infection risk in outdoor urban areas with poor *** address this gap,we propose a modified Wells-Riley model based on the purging flow rate(QPFR),by using computational fluid dynamics(CFD)*** model quantifies the outdoor risk in 2D street canyons with different approaching wind speeds,urban heating patterns and aspect ratios(building height to street width).We show that urban morphology plays a critical role in controlling airborne infectious disease transmission in outdoor environments,especially under calm winds;with deep street canyons(aspect ratio>3)having a similar infection risk as typical indoor *** ground and leeward wall heating could reduce the risk,windward heating(e.g.,windward wall~10 K warmer than the ambient air)can increase the infection risk by up to 75%.Our research highlights the importance of considering outdoor infection risk and the critical role of urban morphology in mitigating airborne infection *** identifying and addressing these risks,we can inform measures that may enhance public health and safety,particularly in densely populated urban environments.

关键词： airborne infection risk street canyon urban ventilation wall heating CFD modelling

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FPGA implementation of 500-MHz high-count-rate high-time-resolution real-time digital neutron-gamma discrimination for fast liquid detectors

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Nuclear Science and Techniques 2024年第8期35卷 101-113页

作者： Hui‑Yin Shen Jing‑Long Zhang Jie Zhang jian‑hang Zhou College of Nuclear Technology and Automation Engineering Chengdu University of TechnologyChengdu 610059China Southwestern Institute of Physics P.O.Box 432Chengdu 610041China

Fast neutron flux measurements with high count rates and high time resolution have important applications in equipment such as *** this study,real-time neutron and gamma discrimination was implemented on a self-developed 500-Msps,12-bit digitizer,and the neutron and gamma spectra were calculated directly on an FPGA.A fast neutron flux measurement system with BC-501A and EJ-309 liquid scintillator detectors was developed and a fast neutron measurement experiment was successfully performed on the HL-2 M tokamak at the Southwestern Institute of Physics,*** experimental results demonstrated that the system obtained the neutron and gamma spectra with a time accuracy of 1 *** count rates of up to 1 Mcps,the figure of merit was greater than 1.05 for energies between 50 keV and 2.8 MeV.

关键词： Neutron-gamma discrimination Liquid scintillation detector Real-time spectrum analyzer

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Adsorption of chloroacetanilide herbicides on soil (I) Structural influence of chloroacetanilide herbicide for their adsorption on soils and its components

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Journal of Environmental Sciences 2001年第1期13卷 37-45页

作者： LIU Wei ping LIU Hui jun ZHENG Wei LU jian hang Institute of Environmental Science Zhejiang University at Yuquan CampusHangzhou 310027China.

Adsorption of chloroacetanilide herbicide acetochlor, alachlor, metolachlor and propachlor on soils and soil components was determined, and the structural differences of these herbicides were used to explain the order of sorptivity. Adsorption isotherms for all herbicide-soil combinations conformed to the Freundlich equation, and Kf increased with increasing soil organic carbon content. Kd on soil humic acid was greater than that on clay, but association of humic acid with clay reduced the overall adsorption. On all soils and soil humic acids, herbicide adsorption decreased in the order: metolachlor > acetochlor > propachlor > alachlor. On Ca2+ - montmorrilonite, the order changed to metolachlor > acetochlor > alachlor > propachlor. FT-IR spectra of herbicide-clay or herbicide-humic acid-clay mixtures showed that H-bonding and charge transfer were the primary interaction pathways between these compounds and the surface of clay or humic acids. The different moieties attached to 2-chloro-acetanilide and their unique arrangement may have influenced the binding mechanisms and thus the sorptivity of these herbicides. This study indicates that the structural difference of pesticides in the same classes may be used as a molecular probe to obtain a better understanding of sorption mechanisms of pesticides on soil.

关键词： adsorption chloroacetanilide herbicides soil organic matter clay

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Superdeformed Bands with △I = 4 Bifurcation of the Odd-A Nuclei in the A-190 Region

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Chinese Physics Letters 2001年第10期18卷 1319-1322页

作者： LIU Yu-Xin ZHOU jian-hang Wang Jiajun Department of Physics Peking UniversityBeijing 100871 The Key Laboratory of Heavy Ion Physics Ministry of Education LaboratoryBeijing UniversityBeijing 100871 Institute of Theoretical Physics Chinese Academy of SciencesP.O.Box 2735y Beijing 100080 Center of Theoretical Nuclear Physics National Laboratory of Heavy Ion AcceleratorLanzhou 730000

The γ-ray energy (Eγ) spectra of the superdeformed (SD) bands of odd-A nuclei in the A- 190 mass region are investigated systematically. It is found that a △1 = 4 bifurcation exists in the SD bands. Within the supersymmetry scheme including many-body interactions and a perturbation possessing the SO(5) (or SU(5)) symmetry on the rotational symmetry, the Eγ spectra, dynamical moments of inertia and Eγ differences δ4Eγ(I) of these bands are evaluated. Quantitative good results are obtained which show that the scheme is powerful to describe the △I = 4 bifurcation. The △I = 4 bifurcation may then come from the perturbation holding the SO(5) (or SU(5)) symmetry on the rotation. From a microscopic point of view, the △I = 4 bifurcation may be a result of the combination of theβ-phonon, γ-phonon and the rotation.

关键词： symmetry bifurcation bands

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Synthesis and Crystal Structure of (H_3O)_2[Cu_3Cl_3(H_2O)_3(NC_9H_(12.5)O_6)_2]

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Chinese Journal of Structural Chemistry 2005年第11期24卷 1302-1305页

作者： Zhang Rui-Bo Zhang jian WEN Yi-hang CHENG jian-Kai LI Zhao-Ji YAO Yuan-Gen State Key Laboratory of Structural Chemistry Fujian Institute of Research on theStructure of Matter The Chinese Academy of Sciences Fuzhou Fujian 350002 China

The new compound, （H3O）2[Cu3Cl3（H2O）3（NC9H12.5O6）2] 1, has been synthesized by the hydrothermal reaction and its structure was determined by single-crystal X-ray diffraction. The crystal is of hexagonal, space group P6 3/m with a = 10.6975（13）, c = 14.881 （3） A, V = 1474.8（4） A^3, C18H31Cl3Cu3N2O15·2（H3O）, Mr = 850.47, Z = 2, Dx = 1.915 g/cm^3, μ= 2.495 mm^-1, F（000） = 866, R = 0.0517 and wR = 0.0900 for 537 observed reflections （1 〉 2a（Ⅰ））. This compound contains two oxonium ions and one [Cu3Cl3（H2O）3（H0.5ntp）2]^2- anion （ntp = nitrilotripropanoato）, in which two tridentate ntp ligands connected by three copper（Ⅱ） ions enclose a cage-like unit. Each copper（Ⅱ） ion is coordinated by one water molecule, one chloride ligand and two carboxylate oxygen atoms from two ntp ligands assume a slightly distorted square-planar geometry. There are O-H…Cl hydrogen bonding interactions between unligated oxonium ions and ligated chlorine atoms of the units resulting in two-dimensional sheets and wheel-like three-dimensional interpenetrating frameworks.

关键词： nitrilotripropionic acid copper compound cage-like structure

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Synthesis and Crystal Structure of a New One-dimensional Double Helical-chain Polymer, {Zn(O_2CC_(12)H_8CO_2)(H_2O)}_n

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Chinese Journal of Structural Chemistry 2005年第10期24卷 1107-1110页

作者： YIN Pei-Xiu Zhang jian WEN Yi-hang CHENG jian-Kai LI Zhao-Ji YAO Yuan-Gen State Key Laboratory of Structural Chemistry Fujian Institute of Research on the Structure of Matter The Chinese Academy of Sciences Fuzhou Fujian 350002 China

A new zinc polymer, {Zn（O2CC12H8CO2）（H2O）}, or {Zn（DPHA）（H2O）}n （O2CC12H8CO2, DPHA = 1,1′ -biphenyl-2,2′-dicarboxylate dianion） has been synthesized under hydrothermal conditions. The crystal is of monoclinic, space group P21/c with a = 12.8418（5）, b = 5.9505（2）, c = 17.2989（5） A, β = 104.020（2）°, V = 1282.52（8） A^3, C14H10O5Zn, Mr= 323.61, Z = 4, Dc = 1.676 g/cm^3,μ = 1.930 mm^-1, F（000） = 656, R = 0.0766 and wR = 0.1871 for 1775 observed reflections （I 〉 2σ（I））. It consists of Zn2（DPHA）2（H2O）2 units, which are further extended into a one-dimensional double helical-chain polymer via Zn-O bonding. The hydrogen bonding interactions extend the helical chains into a two-dimensional layer structure.

关键词： zinc polymer DPHA ligand one-dimensional double helical-chain,two-dimensional layer structure

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A fluorescent probe for fluoride ion based on 2-aminopyridyl-bridged calix[6]arene

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Chinese Chemical Letters 2009年第10期20卷 1191-1194页

作者： jian hang Mai Jun Min Liu Shao Yong Li Huan Feng jiang School of Chemistry and Chemical Engineering of Sun Yat-Sen University Guangzhou 510275 China College of Chemistry South China University of Technology Guangzhou 510640 China College of Pharraacy Tianjin Medical University Tianjin 300070 China

An 2-anfinopyddyl-bddged calix[6]arene on the upper rim fixed in cone conformation （3） was successfully synthesized and its highly selective recognition towards fluoride ion was proved by fluorescent and 1H NMR titr... 详细信息

关键词： Calixarene Fluorescent chemosensor Fluoride ion

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