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Numerical study on wake characteristics of high-speed trains

Acta Mechanica Sinica 2013年第6期29卷 811-822页

作者： Shuan-Bao yao Zhen-Xu Sun Di-Long Guo Da-Wei Chen Guo-Wei Yang Key Laboratory for Mechanics in Fluid Solid Coupling Systems Institute of MechanicsCAS CSR Qingdao Sifang Locomotive Co.Ltd.

Intensive turbulence exists in the wakes of high speed trains, and the aerodynamic performance of the trailing car could deteriorate rapidly due to complicated features of the vortices in the wake zone. As a result, the safety and amenity of high speed trains would face a great challenge. This paper considers mainly the mechanism of vortex formation and evolution in the train flow field. A real CRH2 model is studied, with a leading car, a middle car and a trailing car included. Different running speeds and cross wind conditions are considered, and the approaches of un- steady Reynold-averaged Navier-Stokes （URANS） and de- tached eddy simulation （DES） are utilized, respectively. Re- suits reveal that DES has better capability of capturing small eddies compared to URANS. However, for large eddies, the effects of two approaches are almost the same. In conditions without cross winds, two large vortex streets stretch from the train nose and interact strongly with each other in the wake zone. With the reinforcement of the ground, a complicated wake vortex system generates and becomes strengthened as the running speed increases. However, the locations of flow separations on the train surface and the separation mechanism keep unchanged. In conditions with cross winds, three large vortices develop along the leeward side of the train, among which the weakest one has no obvious influence on the wake flow while the other two stretch to the tail of the train and combine with the helical vortices in the train wake. Thus, optimization of the aerodynamic performance of the trailing car should be aiming at reducing the intensity of the wake vortex system.

关键词： Wake flow structures URANS DES High speed trains

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SUPPRESSION OF CELL ADHESION ON POLYACRYLONITRILE-BASED MEMBRANES BY THE ANCHORING OF PHOSPHOLIPID MOIETIES

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Chinese Journal of Polymer Science 2006年第1期24卷 103-106页

作者： Xiao-jun Huang Xiao-dan Huang Ai-fu Che Zhi-kang Xu Ke yao Institute of Polymer Science Zhejiang University Hangzhou 310027China Medical College Zhejiang University Hangzhou 310027 China

In this work, the membrane surface of poly（acrylonitrile-co-2-hydroxyethyl methacrylate）（PANCHEMA） was chemically modified by anchoring of phospholipid moieties. The process involved the reaction of hydroxyl groups on the membrane surface with 2-chloro-2-oxo-1,3,2-dioxaphospholane （COP） followed by the ring-opening reaction of COP with trimethylamine. Chemical differences between the original and the modified membranes were characterized by FT-IR and XPS, It was found that the amount of macrophage adhered on the modified membrane surface is substantially lower than that on polyacrylonitrile （PAN） and PANCHEMA membranes under the same condition, The morphological change of the adherent cell is also suppressed by the generation ofphospholipid moieties on the membrane surface.

关键词： Acrylonitrile copolymer Membrane Surface modification Phospholipid moieties Cell adhesion.

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Au-catalysed free-standing wurtzite structured InAs nanosheets grown by molecular beam epitaxy

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Nano Research 2019年第11期12卷 2718-2722页

作者： Qiang Sun Han Gao Xiaomei yao Kun Zheng Pingping Chen Wei Lu Jin Zou Materias Engineering The University of Queensland St LuciaQLD 4072Australia State Key Laboratory for Infrared Physics Shanghai Institute of Techrical PlhysicsChinese Acadenry of Sciences500 Yutian RoadShanghai 200083China University of Chinese Academy of Sciences No.19A Yuquan RoadBeijing 100049China Institute of Microstructure and Properties of Advanced Materials Beijing University of TechnologyBeijing 100124China Centre for Microscopy and Microanalysis The University of QueenslandSt LuciaQLD 4072 Alustraia

In this study,we report the growth of free-standing InAs nanosheets using Au catalysts in molecular beam *** structural characterizations suggest that wurtzite structured InAs nanosheets,with features of extensive{1120}surfaces,grown along thedirection and adopted{0001}nanosheet/catalyst interfaces,are initiated from wurtzite structured[0001]nanowires as the inclined epitaxial growth due to relatively higher In concentrations in Au catalysts,and grown from these inclined nanostructures through catalyst-induced axial growth and their enhanced lateral growth under the high growth *** on the facts that the nanosheets contain large low energy{1120}surfaces and{0001}nanosheet/catalyst interfaces,the growth of our nanosheets is a thermodynamically driven *** study provides new insights into fabricating free-standing Ⅲ-Ⅴ nanosheets for their applications in future nanoscale devices.

关键词： InAs nanosheet wurtzite structure catalyst supersaturation molecular beam epitaxy

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Metabolomic profiles in a green alga (Raphidocelis subcapitata) following erythromycin treatment: ABC transporters and energy metabolism

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Journal of Environmental Sciences 2023年第2期124卷 591-601页

作者： Jiezhang Mo Zhihua Ma Shiwei Yan Napo KM Cheung Fangshe Yang Xiunan yao Jiahua Guo Shaanxi Key Laboratory of Earth Surface System and Environmental Carrying Capacity College of Urban and Environmental SciencesNorthwest UniversityXi’an 710127China State Key Laboratory of Marine Pollution and Department of Chemistry City University of Hong KongKowloonHong KongChina

A recent study showed that erythromycin(ERY)exposure caused hormesis in a model alga(Raphidocelis subcapitata)where the growth was promoted at an environmentally realistic concentration(4μg/L)but inhibited at two higher concentrations(80 and 120μg/L),associated with opposite actions of certain signaling pathways(e.g.,xenobiotic metabolism,DNA replication).However,these transcriptional alterations remain to be investigated and verified at the metabolomic *** study uncovered metabolomic profiles and detailed toxic mechanisms of ERY in *** using *** analysis showed that metabolomic pathways including ABC transporters,fatty acid biosynthesis and purine metabolism were associated with growth promotion in algae treated with 4μg/L *** overcompensation was possibly activated by the low level of ERY in algae where more resources were reallocated to efficiently restore the temporary impairments,ultimately leading to the outperformance of *** contrast,algal growth inhibition in the 80 and 120μg/L ERY treatments was likely attributed to the dysfunction of metabolomic pathways related to ABC transporters,energy metabolism and metabolism of *** from binding of ERY to the 50S subunit of ribosomes to inhibit protein translation as in bacteria,the data presented here indicate that inhibition of protein translation and growth performance of algae by ERY may also result from the suppression of amino acid biosynthesis and aminoacyl-tRNA *** study provides novel insights into the dose-dependent toxicity of ERY on ***.

关键词： Hormesis Metabolome ABC transporters DNA replication Microalgae Macrolide antibiotic

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Numerical Simulation of Fractal Agglomerating-Growth of Al_2O_3Inclusions in Tundish

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Journal of Iron and Steel Research International 2013年第11期20卷 7-12页

作者： GUO Luo-fang LI Hong LING Hai-tao WANG yao SONG Wen-chen State Key Laboratory of Advanced Metallurgy University of Science and Technology Beijing School of Metallurgical and Ecological Engineering University of Science and Technology Beijing

Based on the Al2O3 inclusion analysis of low-carbon aluminum killed steel in tundish of a domestic steel company and fractal theory analysis, a mathematical model of fractal agglomerating growth of Al2O3 inclusions in tundish was established. The results indicated that： large swirl flows exist in both sides of inlet, space between weir and dam, and large zone above outlet, in which monomer and agglomerated inclusion particles accumulate easily; the agglomerated inclusions with hydrodynamic diameter of 6-9.8 μm were quickly generated less than 16 s, but those inclusions with hydrodynamic diameter more than 11 μm were difficult to form; the number density of agglomerated inclusion rapidly increased first, then slowly reduced, so the form and quantity distribution of agglomerated inclu sions can be controlled by controlling the residence time of inclusion particles in tundish.

关键词： tundish fractat theory agglomerating growth fractal dimension

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Phase Transition and Critical Phenomenon Occurring in Granular Matter

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Chinese Physics Letters 2019年第9期36卷 32-35页

作者： yao-Dong Feng Tao Su Qing-Fan Shi Gang Sun Department of Physics Beijing Institute of TechnologyBe让ing 100081 Beijing Key Laboratory for Nanomaterials and Nanodevices Institute of PhysicsChinese Academy of SciencesBe让ing 100190 School of Physical Sciences University of Chinese Academy of SciencesBeijing 100190

We investigate the granular flow states in a channel with bottleneck by molecular dynamics *** study is restricted only on a selected key area rather than on the whole system to focus on the flow properties of a single granular state.A random force field is introduced to control the granular *** is also pointed out that the flow rate in the granular flow can be correlated with the pressure,which leads us to carry out a comprehensive study similar to the classical study for general liquid-gas phase *** results show that the dilute flow state and the dense flow state of the granules are similar to the gas state and the liquid state of general substances,respectively,and the properties of phase transition and critical phenomenon are also similar to those occurring in general substances.

关键词： simulation Phase Transition and Critical Phenomenon Occurring in Granular Matter

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Microstructure and properties of high-strength Cu–Ni–Si–(Ti) alloys

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Rare Metals 2021年第11期40卷 3251-3260页

作者： Yi-Hai Yang Sheng-yao Li Zhen-Shan Cui Zhou Li Yun-Ping Li Qian Lei State Key Lab for Powder Metallurgy Central South UniversityChangsha 410083China School of Physical and Mathematical Science Nanyang Technological UniversitySingapore 637371Singapore School of Materials Science and Engineering Central South UniversityChangsha 410083China

The tradeoff between the strength and the fracture elongation in the high-strength Cu-Ni-Si alloy became a hot research topic ***-Ni-Si-(Ti) alloys were fabricated in a vacuum induction melting furnace to study the effects of titanium on the microstructure and mechanical properties of Cu-Ni-Si alloys with different thermo-mechanical *** homogenization at 900℃ for 4 h,hot-rolled by 80%,solution treatment at 970℃ for 2 h,cold-rolled by 50%,and finally aged at 450℃ for 180 min,the studied Cu-10 Ni-Si-2 Ti alloy achieved the hardness of HV 252.4,electrical conductivity of 23.6% IACS,tensile strength of 764.4 MPa,yield strength of 622.26 MPa,fracture elongation of 10.4%,and strength-elongation product of 7.95 GPa%,which are less than those of the studied Cu-10 Ni-2 Si *** addition of Ti contributed to refining the microstructure,suppressing the decreasing trend in mechanical properties after peak hardening,and arousing a primary substructure strengthening mechanism rather than the precipitation strengthening in Cu-Ni-Si *** findings provide essential understandings of the effects of the Ti on Cu-Ni-Si system alloys,and the designed Cu-Ni-Si alloys with highstrength and fracture elongation could fulfill some requirements of the electronic and electrical industry.

关键词： Copper alloy Microstructure Strength Electrical conductivity

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Mitochondria-targeted ratiometric fluorescent probes for micropolarity and microviscosity and their applications

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Chinese Chemical Letters 2019年第5期30卷 1071-1074页

作者： Jingjing Cui Yuhua yao Cong Chen Rui Huang Weibing Zhang Junhong Qian Shanghai Key Laboratory of Functional Materials Chemistry School of Chemistry & Molecular Engineering East China University of Science and Technology

Two fluorescent“off-on”probes YYH1 and YYH2 were used for the detection of mitochondrial polarity and *** probes have two emission bands:The peak of shorter wavelength was sensitive to the polarity,while that in longer wavelength region was sensitive to the viscosity,which enables us to detect medium polarity and viscosity *** lg(Ishort/Ilong)of YYH1 exhibited linear relationship to the solvent polarity,while that of YYH2 was closely related to the solvent ***,both probes showed potential in bioimaging mitochondrial polarity or viscosity in living cells.

关键词： Fluorescent probe Mitochondria Microviscosity Micropolarity

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STUDY ON THE SYNTHESIS AND PROPERTIES OF POLY(ESTER-IMIDEETHER)MULTIBLOCK COPOLYMERS

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Chinese Journal of Polymer Science 2000年第1期18卷 9-13页

作者： Zu-yao Shan Zhen-yi Li Institute of Chemistry, Chinese Academy of Sciences, Beijing 100080, China Chinese Acad Sci Inst Chem Beijing 100080 Peoples R China

A new class of poly(ester-imide-ether) multiblock copolymers was synthesized by transes-terification and melt copolymerization of dimethyl terephthalate (DMT) and N-(4-carbomethoxyphenyl)-4-(carbomethoxy)-phthalimide with ethylene glycol (EG) and polytetramethylene glycol (PTMG). The structure of the above copolymers was characterized by H-1-NMR and IR spectroscopy. Some properties of the coplymers were also examined. It was found that their mechanical properties and heat stability, compared with poly(ether-ester) copolymers, were obviously improved.

关键词： N-(4-carbomethoxyphenyl)-4-(carbomethoxy)-phthalimide polyester-polyether copolymer poly-(ester-imidether) multiblock copolymer imide modification

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A global empirical model for estimating zenith tropospheric delay

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Science China Earth Sciences 2016年第1期59卷 118-128页

作者： yao Yi Bin ZHANG Bao XU Chao Qian HE Chang Yong YU Chen YAN Feng School of Geodesy and Geomatics Wuhan University Key Laboratory of Geospace Environment and Geodesy Ministry of Education

Tropospheric delay acts as a systematic error source in the Global Navigation Satellite Systems(GNSS) positioning. Empirical models UNB3, UNB3 m, UNB4 and EGNOS have been developed for use in Satellite-Based Augmentation Systems(SBAS). Model performance, however, is limited due to the low spatial resolution of the look-up tables for meteorological parameters. A new design has been established in this study for improving performance of the tropospheric delay model by more effectively eliminating the error produced by tropospheric delay. The spatiotemporal characteristics of the Zenith Tropospheric Delay(ZTD) were analyzed with findings that ZTD exhibits different annual variations at different locations and decreases exponentially with height increasing. Spherical harmonics are utilized based on the findings to fit the annual mean and amplitude of the ZTD on a global scale and the exponential function is utilized for height corrections, yielding the ZTrop model. On a global scale, the ZTrop features an average deviation of ?1.0 cm and Root Mean Square(RMS) of 4.7 cm compared with the International GNSS Service(IGS) ZTD products, an average deviation of 0.0 cm and RMS of 4.5 cm compared with the Global Geodetic Observing System(GGOS) ZTD data, and an average deviation of ?1.3 cm and RMS of 5.2 cm compared with the ZTD data from the Constellation Observing System of Meteorology, Ionosphere, and Climate(COSMIC). The RMS of the ZTrop model is 14.5% smaller than that of UNB3, 6.0% smaller than that of UNB3 m, 16% smaller than that of UNB4, 14.5% smaller than that of EGNOS and equivalent to the sophisticated GPT2+Saas model in comparison with the IGS ZTD products. The ZTrop, UNB3 m and GPT2+Saas models are finally evaluated in GPS-based Precise Point Positioning(PPP), as the models act to aid in obtaining PPP position error less than 1.5 cm in north and east components and relative large error(>5 cm) in up component with respect to the random walk approach.

关键词： Zenith tropospheric delay Spherical harmonics Exponential function ZTrop model

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