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Numerical simulation of broken pin effects on the flow field and cooling performance of a double-wall cooling configuration

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Chinese Journal of Aeronautics 2021年第2期34卷 358-375页

作者： wenjing gao Honglin LI Lei LI Zhe’nan ZHAO Zhufeng YUE Department of Engineering Mechanics Northwestern Poly technical UniversityXian 710129China

In this paper, the flow characteristics of the double wall structure are presented and the effect of the broken pin size on the cooling performance and flow field of the double wall configuration is investigated. A periodic plate model with seven units is adopted, and there are an impingement hole and a film hole in each unit. Under five blowing ratios, six different sizes of the broken pin are compared, and the double wall configuration without broken pins is taken as the *** results show that if the broken pins height is too small, the cooling effectiveness usually cannot be improved. With the presence of broken pins with a height of more than 0.4, the effectiveness is improved due to the enhancement of reattachment and recirculation of coolant. With the increase of the broken pin height, the cooling effectiveness increases. However, the increase of the diameter does not always improve the cooling performance, since the limiting effect of the wall jet. In this study, Case 6 with the largest broken pin always has the best cooling performance, but also the largest flow resistance. In Case 6 temperature is reduced by almost 15 K compared to the baseline, and more areas have relatively higher cooling effectiveness.

关键词： Broken pin Computational Fluid Dynamics Cooling performance Double wall configuration Turbine blades

Ultrathin two-dimensional medium-entropy oxide as a highly efficient and stable electrocatalyst for oxygen evolution reaction

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Nano Research 2024年第4期17卷 2555-2562页

作者： Guangyuan Yan Tianlu Wang Biwei Zhao wenjing gao Tong Wu Liming Ou School of Mechanical Electronic and Control EngineeringBeijing Jiaotong UniversityBeijing 100044China

Medium-entropy oxides(MEOs)with broad compositional tunability and entropy-driven structural stability,are receiving booming attention as a promising candidate for oxygen evolution reaction(OER)***,ultrathin two-dimensional(2D)nanostructure offers extremely large specific surface area and is therefore considered to be an ideal catalyst ***,it remains a grant challenge to synthesize ultrathin 2D MEOs due to distinct nucleation and growth kinetics of constituent multimetallic elements in 2D anisotropic *** this work,an ultrathin 2D MEO(MnFeCoNi)O was successfully synthesized by a facile and low-temperature ionic layer epitaxy *** from multi-metal synergistic effects within ultrathin 2D nanostructure,this 2D MEO(MnFeCoNi)O revealed excellent OER electrocatalytic performance with a quite low overpotential of 117 mV at 10 mA·cm^(-2) and an impressive stability for 120 h continuous operation with only 6.9%***,the extremely high mass activity(5584.3 A·g^(-1))was three orders of magnitude higher than benchmark RuO_(2)(3.4 A·g^(-1))at the same overpotential of 117 *** work opens up a new avenue for developing highly efficient and stable electrocatalysts by creating 2D nanostructured MEOs.

关键词： medium-entropy oxide two-dimensional nanomaterials ionic layer epitaxy oxygen evolution reaction electrocatalysis

Research on the Influence of Guide Blade Trailing Edge Structure on Turbine Performance

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Journal of Thermal Science 2019年第3期28卷 472-483页

作者： gao wenjing LI Lei YUE Zhufeng LI Honglin XIE Gongnan TONG Fujuan School of Mechanics Civil Engineering and Architecture Northwestern Polytechnical University School of Marine Science and Technology Northwestern Polytechnical University

The complex structure at trailing edge reduces the manufacturing precision, which results in an error in the size of the trailing edge structure. In this study, the performance of a stage high-pressure turbine(HP turbine) is calculated out in three dimensions. In the HP turbine guide vane, the trailing edge cutback configuration is adopted. Through three-dimensional simulation, the complex flow around the trailing edge with cutback cooling configuration is presented in this study, and the manufacturing precision reduction due to the complex structure at trailing edge is considered. Furthermore, the effect of trailing edge lip thickness and deflection of the stator on the turbine performance is discussed. Overall, as the press-side lip thickness increasing, the turbine efficiency and turbine inlet flow are reduced. However, the changes in the turbine work output are relatively complex. On the other hand, as the spacing between suction-side lip and press-side lip increases, turbine performance becomes worse. Both of the turbine efficiency and the turbine work output become smaller, while the turbine inlet flow becomes bigger. The effect of the spacing between suction-side lip and press-side lip is obviously greater than that of the press-side lip thickness. The change of the press-side lip thickness has little effect on the relation between the turbine performance and the spacing between suction-side lip and press-side lip. However, when the spacing between suction-side lip and press-side lip deviates from the baseline value, the effect law of the press-side lip thickness on the turbine performance will be affected. As the press-side lip thickness increases, it leads to an increase in the low-velocity zone at both of the pressure-side and suction-side trailing edge. And more main stream is affected or mixed into the wake flow. When the spacing between suction-side lip and press-side lip becomes smaller, the low-velocity zone at the trailing edge is smaller, and the ch

关键词： high pressure turbine trailing edge structure turbine performance

Progressive Fusion Network Based on Infrared Light Field Equipment for Infrared Image Enhancement

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IEEE/CAA Journal of Automatica Sinica 2022年第9期9卷 1687-1690页

作者： Yong Ma Xinya Wang wenjing gao You Du Jun Huang Fan Fan the Electronic Information School Wuhan UniversityWuhan 430072China

Dear Editor,3×3 Infrared imaging,generally,of low quality,plays an important role in security surveillance and target *** this letter,we improve the quality of infrared images by combining both hardware and *** this end,an infrared light field imaging enhancement system is built for the first time,including a infrared light field imaging device,a large-scale infrared light field dataset(IRLF-WHU),and a progressive fusion network for infrared image enhancement(IR-PFNet).

关键词： hardware Infrared Image

MPIN:a macro-pixel integration network for light field super-resolution

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Frontiers of Information Technology & Electronic Engineering 2021年第10期22卷 1299-1310页

作者： Xinya WANG Jiayi MA wenjing gao Junjun JIANG Electronic Information School Wuhan UniversityWuhan 430072China School of Computer Science and Technology Harbin Institute of TechnologyHarbin 150001China

Most existing light field(LF)super-resolution(SR)methods either fail to fully use angular information or have an unbalanced performance distribution because they use parts of *** address these issues,we propose a novel integration network based on macro-pixel representation for the LF SR task,named *** the entire LF image simultaneously,we couple the spatial and angular information by rearranging the four-dimensional LF image into a two-dimensional macro-pixel ***,two special convolutions are deployed to extract spatial and angular information,*** fully exploit spatial-angular correlations,the integration resblock is designed to merge the two kinds of information for mutual guidance,allowing our method to be *** the macro-pixel representation,an angular shuffle layer is tailored to improve the spatial resolution of the macro-pixel image,which can effectively avoid *** experiments on both synthetic and real-world LF datasets demonstrate that our method can achieve better performance than the state-of-the-art methods qualitatively and ***,the proposed method has an advantage in preserving the inherent epipolar structures of LF images with a balanced distribution of performance.

关键词： Light field Super-resolution Macro-pixel representation

Cold-chain transmission, asymptomatic infection, mass screening, vaccine, and modelling: what we know so far for coronavirus disease 2019 control and experience in China

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Medical Review 2022年第1期2卷 1-2页

作者： wenjing gao Liming Li Department of Epidemiology&Biostatistics School of Public HealthPeking UniversityBeijingChina Department of Epidemiology&Biostatistics School of Public HealthPeking University38 Xueyuan RoadHaidian DistrictBeijing 100191China Peking University Centre for Public Health and Epidemic Preparedness&Response Beijing 100191China

Coronavirus disease 2019(COVID-19)pandemic has continued to spread rapidly across the *** the past nearly two years,there have been over 267 million confirmed COVID-19 cases including over five million deaths globally reported to WHO[1].Facing this unprecedented public health crisis which we have not seen in a century,global experts rapidly expand scientific knowledge on this new virus,to track the spread and virulence of the *** countries develop response strategies and practices tailored to their own specific epidemiological situations,resources,and values of individuals living in their countries[2].

关键词： globally continued spread

Multi-Wavelength Ultra-Weak Fiber Bragg Grating Arrays for Long-Distance Quasi-Distributed Sensing

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Photonic Sensors 2022年第2期12卷 185-195页

作者： wenjing gao Jianxia LIU Huiyong GUO Xin JIANG Shaofa SUN Haihu YU Hubei Key Laboratory of Radiation Chemistry and Functional Materials Hubei University of Science and TechnologyXianning437100China National Engineering Laboratory for Fiber Optic Sensing Technology Wuhan University of TechnologyWuhan 430070China

Fiber Bragg grating(FBG)array,consisting of a number of sensing units in a single optical fiber,can be practically applied in quasi-distributed sensing *** signal crosstalk occurring between large-serial of identical FBGs,however,has limited the further increase in the number of sensing units,thus restricting applications only for short-distance sensing *** reduce the signal crosstalk,we design two novel types of 10-kilometer-long FBG arrays with 10000 equally spaced gratings,written on-line using a customized grating inscription system,which is affiliated to a drawing *** factors causing signal crosstalk,such as spectral shadowing and multiple reflections,are firstly investigated in *** with the theoretical findings,experimental results are proving that ultra-weak(the reflectivity of—40 dB)and multi-wavelength gratings of a number more than 10000 can be readily identified,with satisfied low *** maximum attenuation of grating signal and minimum signal-to-noise ratio(SNR)in a single-wavelength array are 10.69 dB and 5.62 dB,*** a comparison,by increasing the number of central wavelengths to three,the attenuation can be effectively reduced to 5.54dB and the minimum SNR has been improved to 8.14 *** current study significantly enhances the multiplexing capacity of FBG arrays and demonstrates promising potentials for establishing large-capacity quasi-distributed sensing networks.

关键词： Multi-wavelength gratings array large scale sensing network crosstalk ultra-weak grating

Drawing Tower In-Line Fabrication and the Spectrum Analysis of Sampled Fiber Grating

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Photonic Sensors 2020年第1期10卷 80-87页

作者： Yu ZHENG wenjing gao Haihu YU Huiyong GUO Shan JIANG Desheng JIANG National Engineering Laboratory for Fiber Optic Sensing Technology Wuhan University of TechnologyWuhan 430070China WUTOS Technology Co. LtdWuhan 430223China

Sampled fiber grating is a special superstructure fiber Bragg grating with a wide range of applications in many *** this work,based on drawing tower in-line fabrication system,a new preparation method of the sampled fiber grating is proposed and experimentally *** result shows that the obtained sampled fiber gratings possess dense reflection spectra,with a minimum reflection peak interval of only 0.09 *** method exhibits promising application prospect in the fabrication of the high-quality sampled fiber *** the other hand,the spectral characteristics of the sampled fiber grating are analyzed when the sub-grating is affected by the external physical quantities such as,in this paper,*** shift and intensity change in the reflection peak of the spectra indicate that the grating is affected differently by micro strains,due to the different spatial positions along the axis of the sampled fiber *** work is aimed at exploring the potential applications of the sampled fiber grating in quasi-distributed micro-area sensing with the millimeter level.

关键词： Sampled fiber grating drawing tower in-line fabrication spectrum analysis grating array sensing application

Asymptomatic and pre-symptomatic infection in Coronavirus Disease 2019 pandemic

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Medical Review 2022年第1期2卷 66-88页

作者： Yutong Wang Ke Zheng wenjing gao Jun Lv Canqing Yu Lan Wang Zijun Wang Bo Wang Chunxiao Liao Liming Li Department of Epidemiology and Biostatistics School of Public HealthPeking University38 Xueyuan RoadHaidian DistrictBeijing 100191China Peking University Centre for Public Health and Epidemic Preparedness and Response Beijing 100191China National Institute for Communicable Disease Control and Prevention Chinese Center for Disease Control and PreventionBeijingChina Meinian Public Health Institute Peking University Health Science CenterBeijingChina

With the presence of Coronavirus Disease 2019(COVID-19)asymptomatic infections detected,their proportion,transmission potential,and other aspects such as immunity and related emerging challenges have attracted people’s *** have found that based on highquality research,asymptomatic infections account for at least one-third of the total cases,whereas based on systematic review and meta-analysis,the proportion is about *** the true transmission potential of asymptomatic cases is difficult but critical,since it may affect national policies in response to *** have summarized the current evidence and found,compared with symptomatic cases,the transmission capacity of asymptomatic individuals is weaker,even though they have similar viral load and relatively short virus shedding *** the outbreak progresses,asymptomatic infections have also been found to develop long *** addition,the role of asymptomatic infection in COVID-19 remains to be further revealed as the severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)variants continue to ***,as asymptomatic infections transmit the SARS-CoV-2 virus silently,they still pose a substantial threat to public ***,it is essential to conduct screening to obtain more knowledge about the asymptomatic infections and to detect them as soon as possible;meanwhile,management of them is also a key point in the fight against COVID-19 community *** different management of asymptomatic infections in various countries are compared and the experience in China is displayed in detail.

关键词： asymptomatic coronavirus disease 2019 presymptomatic severe acute respiratory syndrome coronavirus 2.