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Suppression of vortex rope oscillation and pressure vibrations in Francis turbine draft tube using various strategies

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Journal of Hydrodynamics 2021年第3期33卷 534-545页

作者： Lei Zhu Rui-zhi Zhang An Yu Li Lu xian-wu luo China Institute of Water Resources and Hydropower Research Beijing100038China State Key Laboratory of Hydroscience and Engineering Department of Energy and Power EngineeringTsinghua UniversityBeijing100084China College of Energy and Electrical Engineering Hohai UniversityNanjing210098China

The vortex rope usually occurs in the draft tube of the Francis turbine operated under part-load conditions,to induce strong low-frequency pressure vibrations,and therefore,is very harmful to the safety of the hydropower *** the present work,three kinds of strategies are extensively investigated,i.e.,the installations of the ventilation and the fin,as well as the hybrid strategy of the air admission through a fin,so as to effectively suppress the vortex rope oscillation and the pressure vibration in the draft tube of a Francis turbine,whose specific speed is 125 *** the unsteady flow simulation,the Reynolds averaged Navier-Stokes(RANS)method is applied coupled with the k-ω SST turbulence model and a homogeneous cavitation *** flow analysis confirms that the low-frequency pressure vibrations are originated from the periodical oscillation of the vortex rope,and the cavitation usually enhances the vortex rope oscillation in the draft *** the part-load condition,the dominant component of the pressure vibration in the draft tube has a frequency,for example,f_(1),lower than the runner rotating frequency f_(n).It is shown that all three strategies can be adopted to alleviate the vortex rope oscillation and the pressure vibrations in the draft tube,but their suppression mechanisms are quite *** ventilation of an adequate amount from the turbine runner cone can change the vortex rope geometry from the spiral type to the cylindrical type,suppress the vortex rope oscillation,and consequently create the homogeneous distributions of the pressure and the pressure gradient in the draft *** the other hand,a fin installed at the draft tube wall can induce a small extra rope,and the interaction between the main vortex rope and the extra rope changes the flow field and alleviates the pressure vibration in the draft *** should be noted that a fin is much more effective to suppress the pressure vibration in the draft tube under the cavitation cond

关键词： Francis turbine vortex rope pressure vibration ventilation fin installation

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Reaction inside a viral protein nanocage： Mineralization on a nanoparticle seed after encapsulation via self-assembly

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Nano Research 2017年第10期10卷 3285-3294页

作者： Wenjing Zhang Zhi-ping Zhang xian-En Zhang Feng Li State Key Laboratory of Virology Wuhan Institute of Virology Chinese Academy of Sciences Wuhan 430071 China University of Chinese Academy of Sciences Beijing 100049 China National Laboratory ofBiomacromolecules CAS Center for Excellence in Biomacromolecules Institute of Biophysics Chinese Academy of Sciences Beijing 100101 China

Protein nanocages are ideal templates for the bio-inspired fabrication of nanomaterials due to several advantageous properties. During the mineralization of nanoparticles （NPs） inside protein nanocages, most studies have employed a common strategy： seed formation inside protein nanocages followed by seeded NP growth. However, the seed formation step is restricted to gentle reaction conditions to avoid damage to the protein nanocages, which may greatly limit the spectrum of seed materials used for NP growth. We put forward a simple route to circumvent such a limitation： encapsulation of a preformed NP as the seed via self-assembly, followed by the growth of an outer metal layer. Using such a method, we succeeded in mineralizing size-tunable Au NPs and Au@Ag core-shell NPs （〈10 nm in diameter） with narrow size distributions inside the virus-based NPs of simian virus 40. The present route enables the utilization of NPs synthesized under any conditions as the starting seeds for nanomaterial growth inside protein nanocages. Therefore, it potentially leads to novel bioinorganic chimeric nanomaterials with tailorable components and structures.

关键词： protein nanocages mineralization gold nanoparticles gold-silver core-shellnanoparticles self-assembly

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利用低场核磁共振技术探究机械损伤对蓝莓果实内部水分状态的影响

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食品科学 2025年第3期46卷 204-211页

作者：罗子旋姜凤利吴沛净宋平丁柯柯沈阳农业大学信息与电气工程学院辽宁沈阳110866

本研究采用自制损伤装置制作不同损伤等级样本(DI组(撞击1次)和DII组(撞击不同位置2次)),利用低场核磁共振技术,在4℃和25℃两种贮存温度条件下,采集蓝莓损伤发生0、6、24 h的波谱信息和质子密度图像信息。结果表明,损伤显著改变了蓝莓... 详细信息

本研究采用自制损伤装置制作不同损伤等级样本(DI组(撞击1次)和DII组(撞击不同位置2次)),利用低场核磁共振技术,在4℃和25℃两种贮存温度条件下,采集蓝莓损伤发生0、6、24 h的波谱信息和质子密度图像信息。结果表明,损伤显著改变了蓝莓内部水分状态与分布。随着时间的延长,受损蓝莓细胞壁水含量A21减少,而细胞质水含量A22在损伤发生后逐渐上升,特别在损伤程度高的DII组,损伤发生24 h后A22增至0 h的1.45倍以上,而液泡水含量A23和总水分含量A2大幅度下降,表明蓝莓损伤后水分重新分配和向外界环境迅速转移。随着损伤程度上升,液泡水主峰整体呈现显著下降和右移的趋势,同时温度的升高进一步加剧了该变化。在25℃条件下,损伤发生6 h和24 h时,出现了4个弛豫峰,弛豫峰的增加标志着蓝莓品质显著劣变。相比于室温(25℃),4℃低温贮存有利于保持果实的完整性,并减缓受损蓝莓水分流失速率。实验结果可为实现蓝莓机械损伤的快速检测和损伤机理研究提供理论基础和数据参考。

关键词：蓝莓机械损伤温度低场核磁共振水分分布

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Identification of miRNAs and their targets in tea (Camellia sinensis)

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Journal of Zhejiang University-Science B(Biomedicine & Biotechnology) 2013年第10期14卷 916-923页

作者： Quan-wu ZHU Yao-ping luo Institute of Tea Science Zhejiang University

MicroRNAs(miRNAs) are endogenous small RNAs playing a crucial role in plant growth and development,as well as stress *** them,some are highly evolutionally conserved in the plant kingdom,this provide a powerful strategy for identifying miRNAs in a new ***(Camellia sinensis) is one of the most important commercial beverage crops in the world,but only a limited number of miRNAs have been *** the present study,a total of 14 new *** miRNAs were identified by expressed sequence tag(EST) analysis from 47 452 available *** *** miRNAs potentially target 51 mRNAs,which can act as transcription factors,and participate in stress response,transmembrane transport,and signal *** of gene ontology(GO),based on these targets,suggested that 37 biological processes were involved,such as oxidation-reduction process,stress response,and *** Encyclopedia of Genes and Genomes(KEGG) pathway enrichment analysis inferred that the identified miRNAs took part in 13 metabolic *** study will help further understanding of the essential roles of miRNAs in *** growth and development,and stress response.

关键词： MicroRNA(miRNA) Camellia sinensis Tea Gene ontology Pathway

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A facile approach to fabricating graphene/waterborne epoxy coatings with dual functionalities of barrier and corrosion inhibitor

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Journal of Materials Science & Technology 2022年第17期112卷 263-276页

作者： Suyun Liu Xuewan Wang Qi Yin Xiongzhi xiang xian-Zhu Fu xian-Zong Wang Jing-Li luo Shenzhen Key Laboratory of Polymer Science and Technology Guangdong Research Center for Interfacial Engineering of Functional MaterialsCollege of Materials Science and EngineeringShenzhen UniversityShenzhen 518060China Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province College of Optoelectronic EngineeringShenzhen UniversityShenzhen 518060China State Key Laboratory of Solidification Processing Center of Advanced Lubrication and Seal MaterialsNorthwestern Polytechnical UniversityXi’an 710072China

A facile and environmentally-friendly method is developed to prepare graphene/waterborne epoxy(WEP)composite *** graphene nanosheets are produced with electrochemical-exfoliation in the solution containing surfactants,cetyl trimethyl ammonium bromide(CTAB)and sodium dodecyl sulfate(SDS).The nanosheets containing solution thus formed are subjected to a quick dialysis and then directly used as a diluent for WEP without any further *** preparation method overcomes the commonly identified problems of aggregations and‘corrosion promotion’effect associated with graphene,and increases the impedance of the composite coatings by more than two orders of *** analysis of anticorrosion performance suggested that the presence of surfactants not only improves the dispersibility of graphene nanosheets but also endows the composite coatings with both barrier and corrosion inhibition *** strategy reported herein may pave the path to the large-scale production of graphene anticorrosion coatings.

关键词： Electrochemical-exfoliation graphene Waterborne epoxy coatings Anticorrosion Inhibition

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AocML： A Domain-Specific Language for Model-Driven Development of Activity-Oriented Context-Aware Applications

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Journal of Computer Science & Technology 2018年第5期33卷 900-917页

作者： Xuan-Song Li xian-ping Tao Wei Song Kai Dong School of Computer Science and Engineering Nanjing University of Science and Technology Nanfing 210093 China State Key Laboratory for Novel Software Technology Nanjing University Nanjing 210023 China School of Computer Science and Engineering Southeast University Nanjing 211189 China

Activity-oriented context-aware （AOCA） applications are representative in pervasive computing. These appli- cations recognize daily-life human activities, perceive the environment status related to the activities, and react to ensure the smooth performance of the activities. Existing research proposed a specific light-weight, incremental method to support the development of such applications; however it is not easy to learn and use. This paper aims to facilitate the development of such applications and improve the productivity of developers. We propose AocML, a textual domain-specific language which provides a high-level abstraction of AOCA applications. Specifically, we first show the software model of AOCA applications and the abstract syntax of AocML. Then, we introduce the concrete syntax of AocML. We also implement the tools for AocML, including the development environment as well as the generation of Java code and ontology specification. Moreover, we use a case study and evaluation to demonstrate the advantages of AocML.

关键词： pervasive computing context-awareness model-driven development domain-specific language

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Study of Oxidation of Glutathione Treated with Hypochlorous Acid by Capillary Electrophoresis

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Chinese Chemical Letters 2001年第7期12卷 623-624页

作者： xian luo Jian De LU Xiao Yun FU Analytical and Testing Center Zhejiang UniversityHangzhou 310027

Capillary electrophoresis (CE) method was developed for the separation and quantification of reduced glutathione (GSH), oxidized glutathione (GSSG) and glutathione sulphonic acid (GSO(3)H). Baseline separation was obtained within five minutes. The effects of reaction time and molar ratio of hypochlorous acid (HOCl) to GSH on the oxidation of GSH were investigated.

关键词： Glutathione oxidation capillary electrophoresis

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Numerical simulation of 3D electromagnetic–thermal phenomena in an induction heated slab

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Journal of Iron and Steel Research International 2020年第4期27卷 420-432页

作者： He-ping Liu xian-hui Wang Liang-ying Si Jian Gong Central Iron and Steel Research Institute Beijing 100081China Shougang Zhixin Qian’an Electromagnetic Material Co. Ltd.Qian’an 064404HebeiChina

A mathematical model was developed to get an insight into 3D electromagnetic–thermal phenomena in an induction heated steel slab with a large width/thickness ratio by solving a fully coupled Maxwell equations and energy conservation *** spatial heat radiation between the slab surface and the refractory wall in an induction furnace was *** electromagnetic induction and temperature distribution features inside the slab with time evolution were *** effects of electromagnetic induction parameters,thermal conductivity of the material and process parameters on the induction heating process were theoretically *** results show that the spatial distribution of induction heat generation inside the slab is *** high work frequency and the low heat conductivity of slab increase the non-uniformity of slab induction heating *** radiative heat loss and heat transfer between the slab and the metal parts used for holding the slab have an important effect on the slab surface *** is necessary to separately control the current input in the multi-layer coil windings along the height direction of furnace and adopt the multi-step heating strategies with time evolution to improve the homogenization of the slab temperature.

关键词： Slab Electromagnetic feld Induction heating Numerical simulation

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Control of Halo-Chaos in Beam Transport Network via Neural Network Adaptation with Time-Delayed Feedback

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Communications in Theoretical Physics 2006年第1期45卷 117-120页

作者： FANG Jin-Qing luo Xiao-Shu Guo-xian China institute of Atomic Energy P.O. Box 275-27 Beijing 102413 China Department of Physics and Electronic Science Guangxi Normal University Guilin 541004 China

Subject of the halo-chaos control in beam transport networks （channels） has become a key concerned issue for many important applications of high-current proton beam since 1990＇. In this paper, the magnetic field adaptive control based on the neural network with time-delayed feedback is proposed for suppressing beam halo-chaos in the beam transport network with periodic focusing channels. The envelope radius of high-current proton beam is controlled to reach the matched beam radius by suitably selecting the control structure and parameter of the neural network, adjusting the delayed-time and control coefficient of the neural network.

关键词： beam transport network periodic focusing channels high-current proton beam halo-chaos neural network adaptation control time-delayed feedback

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Seismic response of the Lengzhuguan slope during Kangding Ms5.8 earthquake

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Journal of Mountain Science 2017年第11期14卷 2337-2347页

作者： WANG Yun-sheng HE Jian-xian luo Yong-hong State Key Laboratory of Geohazard Prevention and Geoenvironmental Protection Chengdu University of Technology Key Laboratory of Shale Gas and Geoengineering Institute of Geology and Geophysics Chinese Academy of Sciences University of Chinese Academy of Sciences

In order to investigate the role of the amplification of peak ground acceleration(PGA) in seismic landslide formation mechanisms and study how earthquake waves interact with rock structures, a few strong-motion seismometers are installed at various locations on both sides of the Lengzhuguan gully. Five strong-motion seismometers were triggered at different depths in a tunnel at the same altitude during the Kangding Ms 5.8 earthquake on November 25 th, 2014. The data reveal that the horizontal peak acceleration(PGA_H) at each site decreased with increasing site depths. The PGAH at the deepest monitoring site(99 m from the tunnel entrance) was approximately half that of the outermost site. The amplitude of the acceleration response spectrum was also attenuated from the entrance inwards, the dynamic magnification factor(β) of the standard acceleration spectrum was less than 3.5, and rate of change was the same as that for the amplitude acceleration response. The Fourier spectra of each monitoring site also decreased from the outside inwards, and the components of the Fourier spectra were more complex at the surface.

关键词： Earthquake Tunnel Ground motionattenuation Topographic effects Lengzhuguan Horizontal peak acceleration

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