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Relationship between the Intensity of Secondary Flow and Convection Heat Transfer in a Helically Coiled Circular Tube with Uniform Wall Temperature

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Journal of Thermal Science 2023年第3期32卷 1007-1022页

作者： ZHANG Jinlong ZHAO Chuangyao WANG Liangbi School of Mechanical Engineering Lanzhou Jiaotong UniversityLanzhouGansu 730070China Key Laboratory of Railway Vehicle Thermal Engineering of MOE Lanzhou Jiaotong UniversityLanzhou 730070China School of Building Services Science and Engineering Xi'an University of Architecture and TechnologyXi'an 710055China

Numerical method is used to investigate fully developed laminar flow in helically coiled circular tube in this *** non-dimensional parameter(secondary flow Reynolds number Se)based on absolute vorticity flux along the mainstream is used to indicate the intensity of secondary flow caused by the centrifugal effect in helically coiled circular *** relationship between the intensity of secondary flow and the intensity of laminar convective heat transfer is *** effects of curvature and torsion on the enhancement of heat transfer are also *** results reveal that the absolute vorticity flux along the mainstream can be used to indicate the local or averaged intensity of secondary flow;the non-dimensional parameter of the absolute vortex along the main flow determines the convective heat transfer and friction *** relationships of Nusselt number and friction factor with the Se are *** effect of curvature on Nusselt number is obvious,but the effect of torsion on Nusselt number is less obvious.

关键词： helically coiled circular tube convective heat transfer heat transfer enhancement secondary flow

Asymptotic analysis of a vibrating cantilever with a nonlinear boundary

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Science China(Physics,Mechanics & Astronomy) 2009年第9期52卷 1414-1422页

作者： C. W. LIM Department of Building and Construction City University of Hong Kong

Nonlinear vibration of a cantilever in a contact atomic force microscope is analyzed via an asymptotic approach. The asymptotic solution is sought for a beam equation with a nonlinear boundary condition. The steady-state responses are determined in primary resonance and subharmonic resonance. The relations between the response amplitudes and the excitation frequencies and amplitudes are derived from the solvability condition. Multivaluedness occurs in the relations as a consequence of the nonlinearity. The stability of steady-state responses is analyzed by use of the Lyapunov linearized stability theory. The stability analysis predicts the jumping phenomenon for certain parameters. The curves of the response amplitudes changing with the excitation frequencies are numerically compared with those obtained via the method of multiple scales. The calculation results demonstrate that the two methods predict the same varying tendencies while there are small quantitative differences.

关键词： asymptotic analysis vibration nonlinear boundary condition beam contact

Method of fabricating artificial rock specimens based on extrusion free forming(EFF)3D printing

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第4期16卷 1455-1466页

作者： Xiaomeng Shi Tingbang Deng Sen Lin Chunjiang Zou Baoguo Liu Key Laboratory for Urban Underground Engineering of the Ministry of Education Beijing Jiaotong UniversityBeijing100044China School of Civil Engineering Beijing Jiaotong UniversityBeijing100044China Department of Civil Engineering Monash UniversityMelbourne3800Australia

Three-dimensional(3D)printing technology has been widely used to create artificial rock samples in rock *** 3D printing can create complex fractures,the material still lacks sufficient similarity to natural *** free forming(EFF)is a 3D printing technique that uses clay as the printing material and cures the specimens through high-temperature *** this study,we attempted to use the EFF technology to fabricate artificial rock *** results show the physico-mechanical properties of the specimens are significantly affected by the sintering temperature,while the nozzle diameter and layer thickness also have a certain *** specimens are primarily composed of SiO_(2),with mineral compositions similar to that of natural *** density,uniaxial compressive strength(UCS),elastic modulus,and tensile strength of the printed specimens fall in the range of 1.65–2.54 g/cm3,16.46–50.49 MPa,2.17–13.35 GPa,and 0.82–17.18 MPa,*** is capable of simulating different types of rocks,especially mudstone,sandstone,limestone,and ***,the simulation of hard rocks with UCS exceeding 50 MPa still requires validation.

关键词： Artificial rock 3D printing Extrusion free forming(EFF) Similarity analysis Mechanical properties

熔盐法制备Ba_(1-x)K_xBiO_3超导体及Ba_(0.6)K_(0.4)BiO_3的稳定性(英文)

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稀有金属材料与工程 2009年第4期38卷 583-586页

作者：崔雅静陈永亮王法社李璟张勇赵勇西南交通大学磁浮技术与磁浮列车教育部重点实验室四川成都610031

利用熔盐法在260°C的低温下制备出了单相Ba1-xKxBiO3(BKBO,0.315≤x≤0.6)样品。磁性测量结果表明,在x值整个范围内的BKBO样品都表现出超导电性,x=0.4时,超导转变温度达到最高值(Tc=30.6 K);粉末X射线衍射结果表明,所有样品中均含有少... 详细信息

利用熔盐法在260°C的低温下制备出了单相Ba1-xKxBiO3(BKBO,0.315≤x≤0.6)样品。磁性测量结果表明,在x值整个范围内的BKBO样品都表现出超导电性,x=0.4时,超导转变温度达到最高值(Tc=30.6 K);粉末X射线衍射结果表明,所有样品中均含有少量的BaCO3杂相,它是由于反应过程中Ba(OH)2.8H2O和空气中的二氧化碳反应造成的;扫描电镜观察BKBO微观形貌为片状。为与熔盐法作比较,利用溶胶-凝胶法制备Ba0.6K0.4BiO3,发现此法难以制备出单相BKBO样品。利用热分析和退火处理来研究熔盐法制备Ba0.6K0.4BiO3的热稳定性,发现样品大约在400°C开始分解,表明Ba0.6K0.4BiO3在400°C以上是不稳定的。

关键词： Ba1-xKxBiO3 熔盐法超导电性

Experimental research on physical properties of saline soil subgrade filler in Chaerhan region

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Research in Cold and Arid Regions 2015年第3期7卷 212-215页

作者： Yu Zhang JianHong Fang JianKun Liu AnHua Xu School of Traffic and Transportation Lanzhou Jiaotong University Qinghai Research Institute of Transportation China School of Civil Engineering Beijing Jiaotong University

In order to improve the engineering stability of saline soil of high chloride content in the Chaerhan salt lake region, six typical characteristics saline soil samples were selected, and tests on their primary physical properties （total salt content, specific gravity of soil, liquid limit, plastic limit, maximum dry density, and optimal water content） were conducted. The relationships among them were analyzed, a series of variation laws between salt content and these basic physical parameters were determined, and regression equations were derived. This research can improve future engineering design and construction in saline soils and can also help prevent subgrade filler from undermining subgrade stability and producing disease.

关键词： saline soil salt content soil physical properties

Coseismic deformation of the 2020 Yutian MW 6.4 earthquake from Sentinel-1A and the slip inversion

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Earthquake Research Advances 2021年第2期1卷 26-32页

作者： Xin Jiang Wei Li Shijie Wang Mingming Jiang Faculty of Geomatics Lanzhou Jiaotong UniversityLanzhou730070China Nation-Local Joint Engineering Research Center of Technologies and Applications for National Geographic State Monitoring Lanzhou730070China Gansu Provincial Engineering Laboratory for National Geographic State Monitoring Lanzhou730070China

A remarkable earthquake struck Yutian,China on June 26th,***,we use Sentinel-1 images to investigate the deformation induced by this *** invert the InSAR observations using a two-step approach:a nonlinear inversion to constrain fault geometries with uniform slip based on the rectangular plane dislocation in an elastic half-space,followed by a linear inversion to retrieve the slip distribution on the fault *** results show that the maximum LOS displacement is 22.6 cm,and the fault accessed to the ruptured characteristics of normal faults with the minor left-lateral strike-slip *** fault model indicates a 210*** main rupture zone concentrates in the depth of 5-15 km,and the fault slip peaks at 0.89 m at the depth of 9 ***,we calculate the variation of the static Coulomb stress based on the optimal fault model,the results suggest that the Coulomb stress of the Altyn Tagh fault and other neighboring faults has increased and more attention should be paid to possible seismic risks.

关键词： Yutian earthquake InSAR Fault slip Static coulomb stress

In situ high-quality LiF/Li_(3)N inorganic and phenyl-based organic solid electrolyte interphases for advanced lithium–oxygen batteries

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Carbon Energy 2024年第9期6卷 29-38页

作者： Qianyan Wang Minsheng Wu Yunkai Xu Chuyue Li Yuanjia Rong Yaling Liao Menglin Gao Xiaoping Zhang Weirong Chen Jun Lu School of Electrical Engineering Southwest Jiaotong UniversityChengduChina College of Chemical and Biological Engineering Zhejiang UniversityHangzhouChina

Lithium metal shows a great advantage as the most promising anode for its unparalleled theoretical specific capacity and extremely low electrochemical ***,uncontrolled lithium dendrite growth and severe side reactions of the reactive intermediates and organic electrolytes still limit the broad application of lithium metal ***,we propose 4-nitrobenzenesulfonyl fluoride(NBSF)as an electrolyte additive for forming a stable organic-inorganic hybrid solid electrolyte interphase(SEI)layer on the lithium *** abundance of lithium fluoride and lithium nitride can guarantee the SEI layer's toughness and high ionic conductivity,achieving dendrite-free lithium ***,the phenyl group of NBSF significantly contributes to both the chemical stability of the SEI layer and the good adaptation to volume changes of the lithium *** lithium-oxygen batteries with NBSF exhibit prolonged cycle lives and excellent cycling *** simple approach is hoped to improve the development of the organic-inorganic SEI layer to stabilize the lithium anodes for lithium-oxygen batteries.

关键词： lithium anode lithium-oxygen batteries reactive oxygen species solid electrolyte interphase

Spectral Diagnosis of Gas Temperature of Atmospheric Pressure Plasma Jet in Helium

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高电压技术 2013年第9期39卷 2260-2266页

作者： CHANG Zhengshi SHAO Xianjun ZHANG Zenghui ZHANG Guanjun State Key Laboratory of Electrical Insulation and Power Equipment School of Electrical Engineering Xi'an Jiaotong University Xi' an 710049 China

For atmospheric pressure plasma jets(APPJ),the gas temperature is essential for their applications.A spectral diagnosis of APPJ’s gas temperature is conducted in this *** optical emission spectra of helium APPJ are captured by using an optical spectrometer ***,the grating secondary spectrum of OH(A2∑+(ν=0)→X2П(ν=0))are used to diagnose the gas temperature of plasmas because the spectrum has excellent ***,the vibrational temperatures are estimated by using the vibration sequence of N2band(SPS,the second positive system).On the basis of the method,some important conclusions were ***,the spectral identifying indicates that the grating primary spectrum covers a whole wavelength range from 200 nm to 900 nm,and that the grating secondary spectrum overlaps with the primary spectrum from 400 nm to 900 ***,the gas temperature(about 320 K)is close to the room temperature,while the vibrational temperature of the N2(SPS)is about 5 000 *** trend of the two temperatures changing with the applied voltage is discussed in the end.

关键词：等离子体射流气体温度光谱诊断氦气常压频谱识别二级光谱振动温度

核受体相关因子1表达下调对多巴胺能细胞酪氨酸羟化酶和神经突起生长的影响

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生理学报 2006年第4期58卷 351-358页

作者：吴云成蔡友庆赵永波费俭上海市第一人民医院神经内科临床神经生化研究室上海200080 中国科学院上海生命科学研究院生物化学与细胞生物学研究所上海200031

将合成的核受体相关因子1(nuclear receptor-related factor 1,Nurrl)特异性短发夹寡核苷酸(small-hairpin RNA,shRNA)序列插入真核表达载体pSilenCircle(pSC),构建Nurrl基因特异性shRNA真核表达载体,转染体外培养多巴胺能神经前体细胞系MN9D,分别采用实时荧光定量PCR和Western blot方法检测其对MN9D细胞内源Nurrl的干扰作用及其对酪氨酸羟化酶(tyrosine hydroxylase,TH)表达的影响,并在倒置显微镜下观察MN9D细胞神经突起生长的情况,探讨Nurrl shRNA表达载体对多巴胺能细胞表型标记物TH和以神经突起延长为特征的细胞成熟的影响。结果表明,脂质体组细胞和转染阴性对照质粒的MN9D细胞内Nurrl、TH的表达正常,而转染Nurrl shRNA真核表达载体(pSC-N1和pSC-N2)的MN9D细胞内Nurrl和TH的mRNA水平明显降低,Nurrl mRNA的下降率分别为62．3%和45．65%,TH mRNA的下降率分别为76．3%和62．6%。同时Nurrl和TH蛋白的表达亦明显下调,Nurrl蛋白的下降率分别为57．4%和72．0%,TH蛋白的下降率分别为79．1%和70．1%。另外,转染Nurrl shRNA真核表达质粒的MN9D细胞神经突起延长有所减少,但是与正常细胞无明显差异。结果提示：Nurrl shRNA真核表达载体能显著下调MN9D细胞内源Nurrl和TH mRNA和蛋白的表达,同时可能对MN9D细胞的神经突起延长有一定的抑制作用。Nurrl shRNA表达载体的成功构建为多巴胺能神经元发育以及帕金森病相关基因的功能研究奠定了基础。

关键词：核受体相关因子1 酪氨酸羟化酶 RNA干扰帕金森病发育神经突起