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Simulation of two-phase plume field of liquid thruster

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Science China(Technological Sciences) 2012年第6期55卷 1739-1748页

作者： he xiaoying he BiJiao CAI GuoBiao School of Astronautics Beihang UniversityBeijing 100191China

When the liquid propellant thruster works,its plume field would contain many propellant liquid droplets,especially at pulse *** droplets may move along with the gas flow and deposit on the components of spacecraft as *** simulation of the plume field involving the gas molecules and liquid droplets is an important part in contamination studies of thruster *** on the PWS software developed by Beihang University(BUAA),axial-symmetric two-phase direct simulation Monte Carlo(DSMC) method is used with the liquid droplet taken as a kind of solid *** computation of gas-to-particle effect and gas reflection on the particle surface are *** inter-particle collision is also *** gas parameters at nozzle exit of 120N engine after 20 ms pulse work are taken as the entrance condition of the numerical *** test cases are conducted for comparison of different collision *** results show that the effects of liquid propellant droplets mainly concentrate near the axis line of *** particle-to-gas collision would cause evident differences in the gas field and subtle differences in the particle *** liquid droplets in the plume field are generally accelerated and convected by the gas *** DSMC method is proved to be a feasible solver to numerically simulate the two-phase flow involving solid phase and rarefied gas flow.

关键词： two-phase plume field DSMC liquid droplet liquid thruster pulse

Extension of the low diffusion particle method for near-continuum two-phase flow simulations

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Chinese Journal of Aeronautics 2013年第1期26卷 37-46页

作者： Su Wei he xiaoying Cai Guobiao School of Astronautics Beihang University

The low diffusion （LD） particle method, proposed by Burt and Boyd, is modified for the near-continuum two-phase flow simulations. The LD method has the advantages of easily coupling with the direct simulation Monte Carlo （DSMC） method for multi-scale flow simulations and dramatically reducing the numerical diffusion error and statistical scatter of the equilibrium particle methods. Liquidor solid-phase particles are introduced in the LD method. Their velocity and temperature updating are respectively, calculated from the motion equation and the temperature equation according to the local gas properties. Coupling effects from condensed phase to gas phase are modeled as momentum and energy sources, which are respectively, equal to the negative values of the total momentum and energy increase in liquid or solid phase. The modified method is compared with theoretical results for unsteady flows, and good agreements are obtained to indicate the reliability of the one-way gas-to-particle coupling models. Hybrid LD-DSMC algorithm is implemented and performed for nozzle discharging gas-liquid flow to show the prospect of the LD-DSMC scheme for multi-scale two-phase flow simulations.

关键词： DSMC method Hybrid simulation Low diffusion particle method Motion relaxation Temperature relaxation Two-phase flow

Optioning Water Rights:A Potential Alternative to the Hanjiang-Weihe River Water Transfer Project,China

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Chinese Geographical Science 2020年第6期30卷 1039-1051页

作者： he xiaoying KANG Hong GU Yaopeng SONG Yuanliang School of Management and Economics Xi'an Technological UniversityXi'an 710021China Zhongguancun Listed Companies Association Beijing 100011China

China has started shifting from relying on supply management to demand management strategy in addressing its water shortage *** option,a financial derivative for water commodity,has been utilized to manage water demands in the United States and Europe since the 1990 s but is still novel to *** this study we analyzed the pros and cons of China’s existing system for water rights transfers and proposed an alternative,flexible trading instrument-water options for *** the uncertainty to water option pricing,this study first conducted an empirical analysis of the water option in the water-receiving area of the Hanjiang-Weihe River Transfer Project of China,and then evaluated the benefits of the water option *** show that water option trading can bring water cost saving and increase the potential industrially added value for industrial enterprises in the receiving area,and trading of short-and-medium term water options is more favorable than the long-term water options *** novel water option trading proposed in this study,once verified through pilot studies,will be helpful in addressing water shortage problems in China.

关键词： water shortage demand management water rights transfer water options water diversion project

Impairment of autophagy promotes human conjunctival fibrosis and pterygium occurrence via enhancing the SQSTM1-NF-κB signaling pathway

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Journal of Molecular Cell Biology 2023年第1期15卷 41-57页

作者： Qin he Yiting Cai Jiani Huang xiaoying he Wei Han Wei Chen Department of Ophthalmology The First Affiliated HospitalSchool of MedicineZhejiang UniversityHangzhou 310003China Institute of Immunology School of MedicineZhejiang UniversityHangzhou 310058China Eye Center of the Second Affiliated Hospital School of MedicineZhejiang UniversityHangzhou 310009China

Pterygium is a common ocular disease with a high recurrence rate,characterized by hyperplasia of subconjunctival fibrovascular ***,an important process to maintain cellular homeostasis,participates in the pathogenic fibrosis of different ***,the exact role of autophagy in pterygium pathogenesis remains ***,we found that autophagic activity was decreased in human pterygium tissues compared with adjacent normal conjunctival *** in vitro model of fibrosis was successfully established using human primary conjunctival fibroblasts(ConFB)treated with transforming growth factor-β1(TGF-β1),evidenced by increased fibrotic level and strong proliferative and invasive *** autophagic activity was suppressed during TGF-β1-or ultraviolet-induced fibrosis of *** autophagy dramatically retarded the fibrotic progress of ConFB,while blocking autophagy exacerbated this ***,SQSTM1,the main cargo receptor of selective autophagy,was found to significantly promote the fibrosis of ConFB through activating the PKCι-NF-κB signaling *** of SQSTM1,PKCι,or p65 in ConFB delayed TGF-β1-induced *** of SQSTM1 drastically abrogated the inhibitory effect of rapamycin or serum starvation on TGF-β1-induced ***,our data suggested that autophagy impairment of human ConFB facilitates fibrosis via activating the SQSTM1-PKCι-NF-κB signaling *** work was contributory to elucidating the mechanism of autophagy underlying pterygium occurrence.

关键词： pterygium autophagy fibrosis SQSTM1 NF-κB

Wet nitrogen oxidation technology and its anisotropy influence on VCSELs

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维普期刊数据库

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Journal of Semiconductors 2018年第12期39卷 208-211页

作者： Yan he xiaoying he Shuai Hu Jiale Su Chong Li Anqi Hu Xia Guo School of Electronic Engineering and State Key Laboratory of Information Photonics and Optical Communications Beijing University of Posts and Telecommunications Department of Information Beijing University of Technology

Vertical cavity surface emitting lasers（VCSELs） are widely used in optical communications and optical interconnects due to their advantages of low threshold, low power consumption and so on. Wet nitrogen oxidation technology, which utilizes H20 molecules to oxidize the Al;Ga;As, is used for electrical and optical mode confinement. In this paper, the effects of oxidation time, oxidation temperature and oxidation anisotropy on the oxidation rate are explored and demonstrated. The ratio of oxidation rate on [0-11] to [011] crystal orientation is defined as oxidation anisotropy coefficient, which decreases with the increase of oxidation temperature and oxidation time. In order to analyze the effect of the oxidation anisotropy on the VCSEL performance, an oxide-aperture of the VCSELs with two difference shapes is designed and then fabricated. The static performance of these fabricated VCSELs has been measured,whose threshold current ratio ～0.714 is a good agreement with that of the theoretical calculation value ～0.785. Our research on wet nitrogen oxidation and its anisotropy serves as an important reference in the batch fabrication of large-area VCSELs.

关键词： wet nitrogen oxidation vertical-cavity surface-emitting laser oxidation anisotropy

Impact of damping on high speed 850 nm VCSEL performance

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Journal of Semiconductors 2018年第11期39卷 51-54页

作者： Shuai Hu xiaoying he Yan he Jiale Su Chong Li Anqi Hu Xia Guo School of Electronic Engineering and State Key Laboratory of Information Photonics and Optical Communications Beijing University of Posts and Telecommunications Department of Information Beijing University of Technology

High speed VCSELs are important optical devices in short-reach optical communication links and interconnects because of their low cost and high modulation speeds. In this paper, the impact of damping on the their static and dynamic characteristics is analyzed and demonstrated. Through the shallow corrosion of the top layer DBR, the VCSELs with different damping is designed and fabricated. With the increase of the surface etch depth from 0 to ～55 nm for 9 μm oxide-aperture VCSEL, the K factor related with the damping is reduced from0.31 to 0.23 ns;. When the etch depth of the VCSEL with 9 μm oxide-aperture is decreased to ～25 nm,output power is increased from 4.03 to 4.70 mW and small signal modulation bandwidth is also increased from15.46 to 16.37 GHz. It shows that there is a tradeoff between damping and differential gain for improving modulation speed.

关键词： VCSELs K factor damping

A tutorial introduction to graphene-microfiber waveguide and its applications

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Frontiers of Optoelectronics 2016年第4期9卷 535-543页

作者： xiaoying he Min XU Xiangchao ZHANG Hao ZHANG Shanghai Engineering Research Center of UlWa-Precision Optical Manufacturing Department of Optical Science and Engineering Fudan University Shanghai 200433 China

Graphene-microfiber with the advantage of graphene material and the microfiber has been hailed as a wonderful waveguide in optics. A tutorial introduction to the graphene-microfiber （GMF） waveguides including the effect of graphene on waveguide, fabrication and applica- tions has been presented. here, we reviewed recent progress in the graphene waveguides from mode-locking and Q-switching in fiber laser to gas sensing and optical modulation. A brief outlook for opportunities and challenges of GMF in the future has been presented. With the novel nanotechnology emerging, GMF could offer new possibilities for future-optic circuits, systems and networks.

关键词： graphene microfiber optical mode locking,optical sensor

Underwater Bessel-like beams with enlarged depth of focus based on fiber microaxicon

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Chinese Optics Letters 2022年第7期20卷 36-40页

作者： xiaoying he Mengyuan Li Lan Rao School of Electronic Engineering Beijing Key Laboratory of Space-Ground Interconnection and Convergenceand State Key Laboratory of Information Photonics and Optical CommunicationsBeijing University of Posts and TelecommunicationsBeijing 100876China

Underwater optical wireless communication,which is useful for oceanography,environmental monitoring,and underwater surveillance,suffers the limit of the absorption attenuation and Mie–Rayleigh scattering of the ***,Bessel-like beams generated by a fiber microaxicon is utilized for underwater wireless ***,the cone angle for generating Bessel-like beams starts from 46°,which is smaller than that in air for Bessel-like *** the cone angle of the fiber microaxicons is about 140°,the depth of focus underwater,which is four times as long as the depth of focus in air,has enlarged about 28μm,36.12μm,and 50.7μm for 470 nm,520 nm,and 632 nm visible *** transmission distance of the Bessel beams for visible lights has been simulated by using henyey–Greenstein–Rayleigh phase function methods and spectral absorption by bio-optical model due to Monte Carlo *** results show that the propagation distance could reach 4000 m,which overcome the limit of the Mie–Rayleigh scattering and absorption attenuation underwater.

关键词： Bessel-like beams depth of focus underwater optical wireless communication

Taylor-Couette流的DSMC数值模拟

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北京航空航天大学学报 2010年第3期36卷 353-356页

作者：何小英贺碧蛟蔡国飙北京航空航天大学宇航学院北京100191

使用圆柱坐标系网格的三维DSMC(Direct Simulation Monte Carlo)模型,对同轴圆柱间Taylor-Couette流中Taylor涡的形成进行了数值模拟,并分析了不同计算域和边界条件下稳定流场中Taylor涡的轴向排列结构.在网格设置和流场参数不变的情况... 详细信息

使用圆柱坐标系网格的三维DSMC(Direct Simulation Monte Carlo)模型,对同轴圆柱间Taylor-Couette流中Taylor涡的形成进行了数值模拟,并分析了不同计算域和边界条件下稳定流场中Taylor涡的轴向排列结构.在网格设置和流场参数不变的情况下,使用轴对称DSMC模型对Taylor涡进行数值模拟,所得Taylor涡的稳定过程与三维结果一致,验证了使用三维DSMC方法来解决微尺度低速的稀薄气流问题的可行性.三维模拟结果表明Taylor涡以较大的圆周速度绕轴旋转,二维模拟则无法体现.对不同的内圆柱旋转速度进行数值模拟,确定了能够产生Taylor涡的临界速度值.

关键词： Taylor涡直接模拟蒙特卡罗三维轴向排列