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Chinese Journal of Aeronautics 2024年第3期37卷 34-48页

作者： Fanzhi ZENG tianxin zhang Denggao TANG Jinping LI Chao YAN School of Aeronautic Science and Engineering Beihang UniversityBeijing 100191China School of Aeronautical Engineering Air Force Engineering UniversityXi’an 710038China

Accurate prediction of Shock-Wave/Boundary Layer Interaction(SWBLI)flows has been a persistent challenge for linear eddy viscosity models.A major limitation lies in the isotropic representation of the Reynolds stress,as assumed under the Boussinesq *** studies have shown promise in improving the prediction capability for incompressible separation flows by perturbing the Reynolds-stress anisotropy ***,it remains uncertain whether this approach is effective for SWBLI flows,which involve compressibility and *** address this issue,this study systematically quantifies the structural uncertainty of the anisotropy for oblique SWBLI *** eigenspace perturbation method is applied to perturb the anisotropy tensor predicted by the Menter Shear–Stress Transport(SST)model and reveal the impacts of anisotropy on the prediction of quantities of interest,such as separation and reattachment positions,wall static pressure,skin friction,and heat *** results demonstrate the potential and reveal the challenges of eigenspace perturbation in improving the SST ***,a detailed analysis of turbulent characteristics is performed to identify the source of *** findings indicate that eigenspace perturbation primarily affects turbulent shear stress,while the prediction error of the SST model is more related to turbulent kinetic energy.

关键词： Shock-wave/boundary layer interaction(SWBLI) Turbulence models Uncertainty analysis Eigenspace perturbation Anisotropy

A three-equation transition model with mechanical considerations

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Chinese Journal of Aeronautics 2022年第11期35卷 178-190页

作者： tianxin zhang Jianqiang CHEN Yatian ZHAO Zaijie LIU Chao YAN School of Aeronautic Science and Engineering Beihang UniversityBeijing 100083China Computational Aerodynamics Institute China Aerodynamics Research&Development CenterMianyang 621000China School of Aeronautics and Astronautics Central South UniversityChangsha 410083China

A three-equation transition model based on the transition V-model is proposed for subsonic flows in this study. Considering the mechanical approximation of the generation process of the pre-transitional vorticities, the value of laminar Reynolds shear stress related to the mean shear deformation was calculated in the original transition V-model. Then a new transition model, named V-SA model, was proposed, which considered the phenomenological process of transition and presented great results for flows with and without pressure gradient. It is well-known that the baseline Shear Stress Transport(SST) turbulence model shows excellent performance of accuracy and robustness in plentiful flow cases, but it is important to predict boundary layer transition. The current model(V-SST) successfully couples the V-model to the SST turbulence model by introducing the effective turbulent viscosity and additional correction terms into the transport equations. A thorough evaluation of its ability to predict transition features is performed versus the well-documented flat plate of ERCOFTAC, including T3A and T3B without pressure gradient, T3L2 and T3L3 with semi-circular leading edge, the three-dimensional 6:1 prolate-spheroid under two angles of attack, and the NLR-7301 airfoil under different Mach numbers. Numerical results show that the current model has an attractive and superior performance in the simulation of boundary layer transition processes.

关键词： Laminar kinetic energy Mechanical consideration Shear stress transport turbulence model Transition model V-model

Lithospheric structures across the Qiman Tagh and western Qaidam Basin revealed by magnetotelluric data collected using a self-developed SEP system

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Science China Earth Sciences 2021年第10期64卷 1813-1820页

作者： Qingyun DI Guoqiang XUE Zhongxing WANG Lanfang HE Renzhong PEI tianxin zhang Guangyou FANG CAS Engineering Laboratory for Deep Resources Equipment and Technology Institute of Geology and GeophysicsChinese Academy of SciencesBeijing 100029China Key Laboratory of Shale Gas and Geoengineering Institute of Geology and GeophysicsChinese Academy of SciencesBeijing 100029China Key Laboratory of Mineral Resources Institute of Geology and GeophysicsChinese Academy of SciencesBeijing 100029China Institutions of Earth Science Chinese Academy of SciencesBeijing 100029China College of Earth and Planetary Sciences University of Chinese Academy of SciencesBeijing 100049China Aerospace Informatory Research Institute Chinese Academy of SciencesBeijing 100094China

Geophysics offers an important means to investigate the physical processes occurring inside the *** particular,since the 1960s,electromagnetic(EM)methods have played important roles in mineral exploration and engineering *** investigation requires extensive data acquisition and experimental analysis based on geophysical ***,high-performance geophysical equipment,particularly EM exploration equipment,has been dominated by large geophysical companies from the United States,Canada,Germany,and other European countries for *** has limited the development of deep exploration technology in ***,we have developed a high-resolution acquisition system with a wireless control unit and a high-power transmitting system for surface EM prospecting(SEP).The new system has been tested in the high-intensity,noisy environment in Jian-sanjiang area,Heilongjiang *** then conducted a field survey on the western edge of Qaidam Basin,Qinghai Province.A highly conductive anomaly was found in the upper mantle below the Qinmantage Mountains,which indicates a possible northward fluid channel that runs from below the Qinmantage Mountains to the bottom of the western crust of the Qaidam *** of this significant feature was made possible by the new SEP for its better resolution than the previous ***,geophysical analysis confirmed that the thick Cenozoic sediments of the Qaidam Basin are underlain by rigid Precambrian basement rocks and are characterized by a series of *** resistivity profile indicates that the Qaidam Basin was formed due to the folding structures in the northern part of the Qinghai-Tibet Plateau which provided an additional evidence for the uplifting of the Qinghai-Tibet Plateau.

关键词： Surface electromagnetic prospecting system(SEP) Self developed system High resolution Western Qaidam Basin Lithospheric structures

DNA/RNA helicase DHX36 is required for late stages of spermatogenesis

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Journal of Molecular Cell Biology 2022年第11期14卷 50-61页

作者： Kejia zhang tianxin zhang Yujie zhang Jinyu Yuan Xinzhe Tang Chaobao zhang Qianqian Yin Yonglian zhang Ming-Han Tong School of Life Science Hangzhou Institute for Advanced StudyUniversity of Chinese Academy of SciencesChinese Academy of SciencesHangzhou 310024China State Key Laboratory of Molecular Biology Shanghai Key Laboratory of Molecular AndrologyShanghai Institute of Biochemistry and Cell BiologyCenter for Excellence in Molecular Cell ScienceUniversity of Chinese Academy of SciencesChinese Academy of SciencesShanghai 200031China

Spermatogenesis is a highly complex developmental process that typically consists of mitosis, meiosis, and spermiogenesis. DNA/RNA helicase DHX36, a unique guanine-quadruplex (G4) resolvase, plays crucial roles in a variety of biological processes. We previously showed that DHX36 is highly expressed in male germ cells with the highest level in zygotene spermatocytes. Here, we deleted Dhx36 in advanced germ cells with Stra8-GFPCre and found that a Dhx36 deficiency in the differentiated spermatogonia leads to meiotic defects and abnormal spermiogenesis. These defects in late stages of spermatogenesis arise from dysregulated transcription of G4-harboring genes, which are required for meiosis. Thus, this study reveals that Dhx36 plays crucial roles in late stages of spermatogenesis.

关键词： Dhx36 meiosis guanine-quadruplex(G4) Spo11 synapsis meiotic recombination crossover

基于电缆早期故障区段定位的柔性直流配电系统保护方法

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电力系统自动化 2023年第4期47卷 163-171页

作者：贾科施志明张旸张恬昕毕天姝新能源电力系统国家重点实验室(华北电力大学) 北京市102206 新能源与储能运行控制国家重点实验室(中国电力科学研究院) 北京市100192

在柔性直流配电系统中,直流极间短路故障使得全网换流器迅速闭锁,快于直流断路器动作时间,导致系统停运,极大降低了系统的可靠性。为此,文中针对直流电缆早期短路故障,提出一种基于早期故障区段定位的线路保护方法。通过本地换流器的主... 详细信息

在柔性直流配电系统中,直流极间短路故障使得全网换流器迅速闭锁,快于直流断路器动作时间,导致系统停运,极大降低了系统的可靠性。为此,文中针对直流电缆早期短路故障,提出一种基于早期故障区段定位的线路保护方法。通过本地换流器的主动注入,从而削弱线路阻抗对注入信号的衰减,显化早期故障特征,实现对早期短路故障的准确识别与区段定位,解决短路故障引发系统失电的问题。为避免频繁注入,提出基于差动电流量测的注入启动判据。PSCAD/EMTDC仿真结果表明该方法能够准确识别与定位早期故障区段,并及时隔离故障支路,且对系统运行影响小,具有一定的抗噪能力,可为柔性直流配电系统持续安全运行提供保障。

关键词：柔性直流电网配电系统线路保护电缆故障主动注入

如何实现云南民族文化强省建设的扬帆起航——在云南省重大文化艺术项目创作领导小组第一次全体会议上的讲话

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民族艺术研究 2008年第4期 4-8页

作者：张田欣中共云南省委

本文对进一步提升云南省文化影响力和竞争力,打造一批独具特色的文化艺术精品,推动云南民族文化强省的建设具有深远的意义。

关键词：民族文化强省扬帆起航文化品牌

基于介质碳化通道电阻与温度映射关系的光伏直流汇集系统早期故障判别

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电网技术 2024年第4期48卷 1645-1653,I0075,I0077,I0078页

作者：张旸贾科张恬昕施志明毕天姝新能源电力系统国家重点实验室(华北电力大学) 北京市昌平区102206 新能源与储能运行控制国家重点实验室(中国电力科学研究院有限公司) 北京市海淀区100192

光伏中压直流汇集系统中,极间短路故障过流很可能迫使换流器在几毫秒内闭锁,保护来不及动作,引发整个系统停运。该问题可通过提前识别并隔离直流线路中的早期故障来解决。然而在直流线路上,早期故障与绝缘缺陷尚缺乏明确的边界,故障检... 详细信息

光伏中压直流汇集系统中,极间短路故障过流很可能迫使换流器在几毫秒内闭锁,保护来不及动作,引发整个系统停运。该问题可通过提前识别并隔离直流线路中的早期故障来解决。然而在直流线路上,早期故障与绝缘缺陷尚缺乏明确的边界,故障检测判据的阈值难以给定。为此,该文提出了基于碳化通道电阻与温度映射关系的早期故障边界给定原则。基于早期故障发展机理,建立了电缆早期故障实验拟合模型,选取介质碳化通道电阻为故障特征量。在计及系统电压控制约束条件下,解析电缆层间温差与碳化通道电阻的映射关系,进而确定早期故障边界。在此基础上提出了基于故障介质碳化通道电阻值的早期故障判据。仿真结果证明了早期故障边界的合理性以及早期故障判据的有效性,能够为光伏中压直流汇集系统的持续安全运行提供保障。

关键词：直流汇集系统早期故障故障边界故障判别