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Illumination and regolith temperature at China's next candidate lunar landing site Shackleton crater

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Science China Earth Sciences 2023年第2期66卷 417-429页

作者： Zhen ZHONG jianguo yan Huaiyu HE Qiling WEN Deyun LIU Jean-Pierre BARRIOT School of Physics and Electronic Science Guizhou Normal UniversityGuiyang550025China State Key Laboratory of Information Engineering in Surveying Mapping and Remote SensingWuhan UniversityWuhan430079China Institute of Geology and Geophysics Chinese Academy of SciencesBeijing100029China Beijing Spacecraft Manufacturing Co. LtdBeijing100094China Observatory Geodetic de Tahiti BP 657098702Faa’aTahitiFrench Polynesia

This study focuses on the illumination and temperature at China’s next lunar candidate landing site Shackleton crater.We used the NASA’s SPICE system to evaluate the terrain obscuration effect on real-time illumination;the resulting illumination map resembles previous studies,validating the methodologies used in our study.In addition,we estimated an accumulated illumination map for the period of likely rover movement.The map indicates the illuminated inner wall of the Shackleton crater is close to 27%of the whole,meaning that the rover will likely receive solar radiation during its movement.Using the real-time illumination and the distributed 1-D thermal diffusion model,we continuously evaluated the regolith temperature for more than 20 years to stabilize the temperature,and selected the temperature of the end time as the initial value used in a thermal study set for July 20,2023 and May 8,2027.Our results indicate the temperature in the permanent shadow region remains nearly constant,thus validating the stability of our estimated initial temperature.Our results also indicate that the surface temperature is more sensitive to transient illumination,but the subsurface temperature is more likely to be associated with the accumulated illumination.This difference indirectly implies that the conductivity of the lunar regolith is inefficient.The locations receiving more solar radiation show a temperature larger than the threshold(~112 K)of ice stability.The permanently shadowed regions can be as cold as 25 K,and such extreme coldness is a hazard to the rover.There are suitable temperature locations which have a warm surface but cold subsurface to preserve water ice.To further ensure normal rover movement,we provided a map of suitable temperature sites and found that these locations exist not only in the Shackleton crater’s inner wall,but also outside the crater.We suggested four trade-off sampling sites with suitable temperatures and gradual slopes.

关键词： Real-time illumination Regolith temperature Shackleton crater Map of landing site

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有压管道瞬变流的非恒定摩阻模型改进

农业工程学报 2024年第8期40卷 80-89页

作者：黄海郭鹏程颜建国徐燕李江西安理工大学水利水电学院西安710048 西安理工大学省部共建西北旱区生态水利国家重点实验室西安710048 新疆维吾尔自治区寒旱区水资源与生态水利工程研究中心(院士专家工作站) 乌鲁木齐830000

有压管道流动系统运行中经常发生水锤现象,极易导致爆管甚至人员伤亡,因此准确预测有压管道内的水锤现象对于保证系统安全运行具有重要意义。在有压管道内的水锤模拟中,以ZIELKE摩阻模型为代表的基于加权函数的非恒定摩阻模型能够描述... 详细信息

有压管道流动系统运行中经常发生水锤现象,极易导致爆管甚至人员伤亡,因此准确预测有压管道内的水锤现象对于保证系统安全运行具有重要意义。在有压管道内的水锤模拟中,以ZIELKE摩阻模型为代表的基于加权函数的非恒定摩阻模型能够描述有压管道瞬变流中的摩阻效应,但存在计算效率低下的问题。为提高计算效率,该研究提出了“先分段,后整体”的两阶段最小二乘拟合方法,建立了包含19个指数项的近似加权函数,并与已有近似加权函数进行对比,同时开展关阀水锤试验,对比了建立的摩阻模型与已有模型的计算效率和精度。结果表明,该研究建立的近似加权函数能够很好地拟合ZIELKE加权函数,其与ZIELKE加权函数的相对百分比误差近似为0;且其适用范围更宽,能够对无量纲时间在t∈[10-9,∞)范围内的非恒定流进行有效模拟。在计算精度方面,建立的模型与ZIELKE模型在阀门和中点处水头的最大相对百分比误差较小,分别为0.17%和0.15%,与URBANOWICZ模型的表现基本相同;在计算效率方面,建立的模型能够使ZIELKE模型计算效率提升约90%,能够使URBANOWICZ模型计算效率提升约30%。该研究建立的模型在适用范围、计算精度和计算效率方面具有较好的综合表现,能够在保证较宽适用范围和较高计算精度的前提下,提升计算效率。研究可为有压管道瞬变流的准确高效模拟提供理论支撑与参考。

关键词：瞬变流水锤管道非恒定摩阻模型加权函数

Sensor fault-tolerant observer applied in UAV anti-skid braking control under control input constraint

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Journal of Systems Engineering and Electronics 2017年第1期28卷 126-136页

作者： Hui Sun jianguo yan Yaohong Qu Jie Ren School of Automation Northwestern Polytechnical University Chengdu Aircraft Industrial (Group) Co. Ltd.

This paper proposes a method for addressing the problem of sensor fault-tolerant control (FTC) for anti-skid braking systems (ABSs). When the wheel velocity sensor of the ABS for unmanned aerial vehicles (UAVs) becomes faulty, wheel velocity failure and feedback instability may occur. Firstly, a fault diagnosis and isolation (FDI) method based on a sliding mode observer approach is introduced to detect and isolate the fault of the sensor. When the wheel velocity sensor is in healthy conditions, the observer works in a diagnosis mode. If faults occur in the sensor, it acts as a wheel velocity estimator. Secondly, an FTC strategy, adopting a feedback compensation structure, is designed with input control constraints. In addition, based on the FDI result, a terminal sliding mode (TSM) controller is designed to guarantee that slip-ratio tracks its appropriate reference values in situations where runways change conditions during landing. The control system switches automatically from control using a wheel velocity sensor to sensorless control mode, so the observer-based FTC scheme is established. It is logical that the ABS keeps observed-state and remains stable when the wheel velocity sensor is broken and during external disturbance. Finally, simulation results show the effectiveness of the proposed method. ? 1990-2011 Beijing Institute of Aerospace Information.

关键词： Braking Control systems Failure analysis Fault tolerance Feedback Sensorless control Sliding mode control Unmanned aerial vehicles (UAV) Velocity Wheels

Functional Cure of Chronic Hepatitis B with Antiviral Treatment in Children having High-level Viremia and Normal or Mildly Elevated Serum Aminotransferase

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Journal of Clinical and Translational Hepatology 2023年第5期11卷 1011-1022页

作者： Jing Li Peiyao Fan Zhiqiang Xu Yi Dong Fuchuan Wang Weiguo Hong Jinfang Zhao Yinjie Gao jianguo yan Lili Cao Chao Zhang Shishu Zhu Fu-Sheng Wang Min Zhang Peking University 302 Clinical Medical School BeijingChina Senior Department of Infectious Diseases The Fifth Medical Center of Chinese PLA General HospitalNational Clinical Research Center for Infectious DiseasesBeijingChina Senior Department of Liver Diseases The Fifth Medical Center of Chinese PLA General HospitalBeijingChina

Background and Aims:There is a lack of data supporting the notion that antiviral treatments can beneft children with chronic hepatitis B(CHB)having high viremia and normal or mildly elevated serum alanine aminotransferase(ALT)levels.We aimed t analyze the efficacy of antiviral treatments in children with CHB and explore the factors associated with functional cure.Methods:Forty-eight children with CHB having high viremia and normal or mildly elevated serum ALT levels were screened in this real-world study.Thirty-two children received either interferon-alpha(IFN-α)monother-apy,IFN-a therapy with a nucleoside analog(NA)add-on,or IFN-α and NA combination therapy.The 16 children in the control group did not receive antiviral treatment.All 48 chil-dren were available for follow-up assessments for the entire 36-month study period.We identified a functional cure with respect to hepatitis B virus(HBV)DNA loss,loss/seroconver-sion of circulating hepatitis B e antigen(HBeAg),and loss of hepatitis B surface antigen(HBsAg)with or without serocon-version.Cox regression analysis was employed to evaluate the factors that may have influenced the functional cure.Re-sults:After 36 months,the cumulative functional cure rate was 56.25%(18/32)in the treated group and 0%(0/16)in the control group(p<0.001).In the treated group,the serum HBV DNA levels declined rapidly at the end of a 6-month visit and the cured children achieved a loss rate of 100%(18/18)within 16 months of beginning treatment,compared with 64.29%(9/14)of the uncured children(p<0.001).The rates of HBeAg seroconversion were significantly higher among the cured children than among the uncured children(p<0.001).All 16 children in the control group maintained high levels of serum HBV DNA and were positive for both serum HBeAg and HBsAg during the entire 36 months of the study period.Func tional cure was associated with younger ages(1-6 vs.7-14 years,p=0.013),CD8^(+)T lymphocyte counts(p=0.013),and B lymphocyte counts(p=0.003).No serious adverse events were observed.Conclusi

关键词： Child HBV Chronic hepatitis B Antiviral therapy Functional cure

Understanding the Moon's internal structure through moonquake observations and remote sensing technologies

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Science China Earth Sciences 2018年第8期61卷 995-1006页

作者： Weifeng HAO Fei LI Chi XIAO jianguo yan Mao YE Chinese Antarctic Center of Surveying and Mapping Wuhan University State Key Laboratory of Information Engineering in Surveying Mapping and Remote Sensing Wuhan University

Explorations for the interior structure of the Moon mainly involve three technologies: the early gravitational observations via circumlunar satellites, the moonquake observations during the Apollo period, and the recent high-resolution remote sensing observations. Based on these technologies, we divided the development of the moon's interior structure into three stages. The first stage is the discovery of high-density anomalous masses(mascons) on the lunar surface with the low-order gravitational field models, which were obtained by observing perturbations of the early lunar orbital satellites. The second stage is the preliminary understanding of the layer structure with the help of moonquake observations during the Apollo period. The third stage is the deep understanding of the structure of the lunar crust, mantle, and core, with the use of high-resolution remote sensing data and the reassessment of moonquake data from the Apollo's mission. This paper gave detailed introduction and comments on different observation technologies, gathered data, and data processing techniques used at the three stages. In addition, this paper analyzed the current issues in the researches on the Moon's internal structure and discussed the prospects for future explorations.

关键词：内部结构遥感技术月亮数据处理技术高分辨率阿波罗遥感数据异常群

受热通道内超临界R134a流动阻力特性试验研究

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太阳能学报 2024年第5期45卷 584-592页

作者：颜建国朱旭涛田浩轩郑书闽西安理工大学省部共建西北旱区生态水利国家重点实验室西安710048

以超临界R134a流体为工质,测试其在内径2 mm圆管内,流体压强p=4.3~4.9 MPa,质量流速G=550~1650 kg/(m^(2)·s),热流密度q=25~75 kW/m^(2)(电加热模拟热源)工况条件下的流动阻力。根据摩擦压降曲线特征,将其划分为类液相区、类两相区和... 详细信息

以超临界R134a流体为工质,测试其在内径2 mm圆管内,流体压强p=4.3~4.9 MPa,质量流速G=550~1650 kg/(m^(2)·s),热流密度q=25~75 kW/m^(2)(电加热模拟热源)工况条件下的流动阻力。根据摩擦压降曲线特征,将其划分为类液相区、类两相区和类气相区3个区域。分析压强、质量流速和热流密度等工况参数对3个区域内的摩擦压降和摩擦因子的影响规律。在类两相区,摩擦因子曲线存在一个明显的峰值特性。将试验数据与已有的摩擦因子关联式进行对比,并进行定量评价。结果显示,已有关联式的预测误差普遍偏大,尤其是在类两相区域。为此,提出一个同时包含密度、黏度和平均普朗特数修正的超临界流体摩擦因子关联式,与试验数据对比显示,97%预测数据均处于±20%的误差范围内。

关键词：可再生能源超临界流体压降多相流摩擦因子超临界有机朗肯循环

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A new high-precision gravity solid tidal model for Precision Gravity Measurement Facility

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Geodesy and Geodynamics 2020年第4期11卷 265-272页

作者： Chuang Xu Rongrui Xu Wenrui Zeng jianguo yan Department of Surveying Engineering School of Civil and Transportation EngineeringGuangdong University of TechnologyGuangzhou510006China State Key Laboratory of Information Engineering in Surveying Mapping and Remote SensingWuhan UniversityWuhan430079China Institute of Geophysics Huazhong University of Science and TechnologyWuhan430074China

It is significant for establishing gravity datum to construct precise gravity solid tidal model,A simple method with relatively low performance is to interpolate tidal parameters from the global gravity solid tide models.A competitive approach is to determine local gravity solid tidal model by harmonic analysis using long-time serial gravity observations.In this paper a new high-precision gravity solid tidal model for Precision Gravity Measurement Facility is estimated from two co-site gravimeters in the cave laboratory using modern international standard data processing techniques,whose accuracy is evaluated further by comparing with previous publications.The results show that:(1)the determined gravity solid tidal models from two co-site gravimeters are in good agreement with each other,of which the maximum differences for amplitude factors and phase delays don’t exceed 0.01700%and 2.50990°,respectively.(2)the performance of the obtained gravity solid tidal model is 0.00411 for amplitude factors and 0.24120°for phase delays,which is a little better than that of previous publications using superconducting gravity data from Wuhan station.(3)our results and methods are corrective and effective.(4)our model is tiny different from that provided by Wuhan station,which implies that it is necessary to construct a gravity solid tidal model for Precision Gravity Measurement Facility,rather than just adopting existing models at Wuhan station.Our results are helpful in realizing the goal of Precision Gravity Measurement Facility.

关键词： Gravity solid tidal model Precision gravity measurement facility Amplitude factor Phase delay

An Independent Degree-eight Mars Gravity Field Model and the Expected Results from the Tianwen-1 Mission

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Research in Astronomy and Astrophysics 2023年第10期23卷 267-276页

作者： Shanhong Liu Jianfeng Cao jianguo yan Hao Huang Xie Li Jean-Pierre Barriot National Key Laboratory of Science and Technology on Aerospace Flight Dynamics Beijing 100094China Beijing Aerospace Control Center Beijing 100094China State Key Laboratory of Information Engineering in Surveying Mapping and Remote SensingWuhan UniversityWuhan 430079China Department of Astronomy Beijing Normal UniversityBeijing 100875China Observatoire Géodésique de Tahiti University of French PolynesiaF-98702 Faa’aBP 6570 TahitiFrench PolynesiaFrance

Tianwen-1 is China's first independent interplanetary exploration mission,targeting Mars,and includes orbiting,landing,and rover phases.Similar to previous Mars missions,the Tianwen-1 orbiter was designed for polar orbits during the scientific mission period but has an exceptional eccentricity of approximately 0.59.We provide the first independent eight-degree Martian gravity field model in this paper,which was developed exclusively by a team working in China with our independent software as well,based on about two months of radiometric Doppler and range data from only the Tianwen-1 mission.This model is independent from the models created by the groups at NASA Jet Propulsion Laboratory and Goddard Space Flight Center in the United States,as well as the Centre National d'Etudes Spatiales in France.Furthermore,in order to optimize the engineering and scientific benefits,we proposed a number of potential orbits for the extended Tianwen-1 mission.In order to solve a higher-degree independent Mars gravity field model,the viability of modifying the perigee height was investigated,with the priority considerations of fuel savings and implementation hazards being controlled.

关键词： gravitation planets and satellites:fundamental parameters methods:observational

An improved gravity method to horizontal tectonic stresses and its applications in Tibet

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Geodesy and Geodynamics 2020年第6期11卷 468-473页

作者： Chuang Xu Hangtao Yu Chaolong Yao Jinbo Li jianguo yan Department of Surveying Engineering School of Civil and TransportationGuangdong University of TechnologyGuangzhou 510006China State Key Laboratory of Information Engineering in Surveying Mapping and Remote SensingWuhan UniversityWuhan430079China College of Natural Resources and Environment South China Agricultural UniversityGuangzhou 510642China

It is significant for identifying mass movement patterns to invert horizontal tectonic stresses at different depths underneath Tibet.In recent years,a large number of achievements focusing on two-dimensional tectonic stresses have been obtained from gravity data.However,three-dimensional tectonic stresses in Tibet are still unknown or debatable.Therefore,in the present study an improved method to multilayer horizontal tectonic stresses using gravity observations is developed.The inverted multilayer horizontal tectonic stresses are in agreement with those from previous studies.In addition,rich tectonic structure and development can be revealed from the inverted multilayer horizontal tectonic stresses:(1)the distribution of horizontal tectonic stresses at various depths shows strong correlation with that of the tectonic elements,where major faults and earthquake epicenters are corresponding with stress highs and the stable basins are consistent with stress lows.(2)the mass movement patterns of whole Tibet present clockwise,and the material movement directions in the west and east are approximately southnorth and east-west,respectively.(3)in eastern Tibet,the eastward materials caused by the south-north extrusion between Indian and Eurasian plates are divided into two parts by the stable Sichuan Block,one flowing nearly southeast and the other moving almost northeast.The inverted multilayer horizontal tectonic stresses may provide direct evidences for mass movement patterns in Tibet.

关键词： Gravity Horizontal tectonic stresses Tibet Multilayer