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AstroPose:Astronaut pose estimation using a monocular camera during extravehicular activities

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Science china(Technological Sciences) 2024年第6期67卷 1933-1945页

作者： LIU ZiBin LI You WANG ChunHui LIU Liang GUAN BangLei SHANG Yang YU QiFeng College of Aerospace Science and Engineering National University of Defense TechnologyChangsha410073China Key Laboratory of Human Factors Engineering China Astronaut Research and Training CenterBeijing100094China

With the completion of the Chinese space station,an increasing number of extravehicular activities will be executed by astronauts,which is regarded as one of the most dangerous activities in human space *** guarantee the safety of astronauts and the successful accomplishment of missions,it is vital to determine the pose of astronauts during extravehicular *** article presents a monocular vision-based pose estimation method of astronauts during extravehicular activities,making full use of the available observation ***,the camera is calibrated using objects of known structures,such as the spacesuit backpack or the circular handrail outside the space ***,the pose estimation is performed utilizing the feature points on the *** proposed methods are validated both on synthetic and semi-physical simulation experiments,demonstrating the high precision of the camera calibration and pose *** further evaluate the performance of the methods in real-world scenarios,we utilize image sequences of Shenzhou-13 astronauts during extravehicular *** experiments validate that camera calibration and pose estimation can be accomplished solely with the existing observation resources,without requiring additional complicated *** motion parameters of astronauts lay the technological foundation for subsequent applications such as mechanical analysis,task planning,and ground training of astronauts.

关键词： monocular camera astronaut pose estimation camera calibration

Effects of Thirty Days Isolation on Attention Networks: A Behavioral and Event-related Potential Study

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Neuroscience Bulletin 2024年第1期40卷 127-132页

作者： Jingda Feng Bin Wu Ziqing Cao Hailong Chen Tianjun Lan Haibo Qin Yusheng Shi Weifen Huang Yinghui Li Department of Aerospace Science and Technology Space Engineering UniversityBeijing 101400China china Astronaut research and training center Beijing 100094China State Key Laboratory of Space Medicine Fundamentals and Application China Astronaut Research and Training CenterBeijing 100094China School of Psychology Shaanxi Normal UniversityXi'an 710000China

Kear Editor,Individuals in isolated,confined,and extreme environments,such as astronauts,researchers wintering over Antarctica,submarine soldiers,and participants in simulated isolation environment experiments,commonly report difficulty in focusing their attention[1,2].However,current experimental findings from studies conducted in such environments are insufficient to fully support these self-reports of reduced *** attention-demanding tasks such as simple reaction time(RT)tasks and dual tasks,including primary pursuit tracking and secondary RT,were not affected in space flight experiments[2,3].

关键词： environments submarine winter

Lattice Boltzmann simulation study of anode degradation in solid oxide fuel cells during the initial aging process

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International Journal of Minerals,Metallurgy and Materials 2024年第2期31卷 405-411页

作者： Shixue Liu Zhijing Liu Shuxing Zhang Hao Wu Hydrogen Energy Industrial Technology Innovation center China Nuclear Power Technology Research InstituteShenzhen 518031China Shenzhen Engineering research center for Hydrogen Safety Shenzhen 518031China

For present solid oxide fuel cells(SOFCs),rapid performance degradation is observed in the initial aging process,and the dis-cussion of the degradation mechanism necessitates quantitative ***,focused ion beam-scanning electron microscopy was em-ployed to characterize and reconstruct the ceramic microstructures of SOFC *** lattice Boltzmann method(LBM)simulation of multiphysical and electrochemical processes in the reconstructed models was *** samples collected from industrial-size cells were characterized,including a reduced reference cell and a cell with an initial aging *** parameters of the reconstructed microstructures revealed a significant decrease in the active triple-phase boundary and Ni connectivity in the aged cell compared with the reference *** LBM simulation revealed that activity degradation is dominant compared with microstructural degradation during the initial aging process,and the electrochemical reactions spread to the support layer in the aged *** microstructural and activity de-gradations are attributed to Ni migration and coarsening.

关键词： solid oxide fuel cell anode degradation focused ion beam-scanning electron microscopy lattice Boltzmann method

Residual stress modeling of mitigated fused silica damage sites with CO_(2)laser annealing

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Chinese Physics B 2024年第3期33卷 509-514页

作者：张传超廖威张丽娟蒋晓龙方振华蒋晓东 Laser Fusion research center China Academy of Engineering PhysicsMianyang 621900China

A numerical model based on measured fictive temperature distributions is explored to evaluate the residual stress fields of CO_(2)laser-annealed mitigated fused silica damage *** proposed model extracts the residual strain from the differences in thermoelastic contraction of fused silica with different fictive temperatures from the initial frozen-in temperatures to ambient *** residual stress fields of mitigated damage sites for the CO_(2)laser-annealed case are obtained by a finite element analysis of equilibrium equations and constitutive *** simulated results indicate that the proposed model can accurately evaluate the residual stress fields of laser-annealed mitigated damage sites with a complex thermal *** calculated maximum hoop stress is in good agreement with the reported experimental *** estimated optical retardance profiles from the calculated radial and hoop stress fields are consistent with the photoelastic *** results provide sufficient evidence to demonstrate the suitability of the proposed model for describing the residual stresses of mitigated fused silica damage sites after CO_(2)laser annealing.

关键词： fused silica damage mitigation residual stress laser annealing

Comparative analysis between single-train passing and double-train intersection in a tunnel

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2024年第5期25卷 429-442页

作者： Jianming DU Qian FANG Xuan ZHANG Hualao WANG Bridge and Tunnel research center Research Institute of Highway Ministry of TransportBeijing 100088China Tunnel and Underground Engineering research center of Ministry of Education Beijing Jiaotong UniversityBeijing 00044China

Aerodynamic pressure significantly impacts the scientific evaluation of tunnel service *** aerodynamic pressure of two trains running in a double-track tunnel is considerably more complicated than that of a single *** used the numerical method to investigate the difference in aerodynamic pressure between a single train and two trains running in a double-track ***,the numerical method was verified by comparing the results of numerical simulation and on-site ***,the characteristics of aerodynamic pressure were ***,the influence of various train-tunnel factors on the characteristics of aerodynamic pressure was *** results show that the aerodynamic pressure variation can be divided into stage I:irregular pressure fluctuations before the train tail leaves the tunnel exit,and stage II:periodic pressure declines after the train tail leaves the tunnel *** addition,the aerodynamic pressure simultaneously jumps positively or drops negatively for a single train or two trains running in double-track tunnel *** pressure amplitude in the two-train case is higher than that for a single *** maximum positive peak pressure difference(P_(STP))and maximum negative peak pressure difference(P_(STN))increase as train speed rises to the power from 2.256 to 2.930 in stage *** P_(STP) and P_(STN) first increase and then decrease with the increase of tunnel length in stage *** P_(STP) and P_(STN) increase as the blockage ratio rises to the power from 2.032 to 2.798 in stages I and II.

关键词： Railway tunnel Aerodynamic effect Pressure characteristic Train speed Tunnel length Blockage ratio

Ultra-high extinction ratio optical pulse generation with a thin film lithium niobate modulator for distributed acoustic sensing

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Photonics research 2024年第1期12卷 40-50页

作者： YUAN SHEN XIAOQIAN SHU LINGMEI MA SHAOLIANG YU GENGXIN CHEN LIU LIU RENYOU GE BIGENG CHEN YUNJIANG RAO research center for Optical Fiber Sensing Zhejiang LaboratoryHangzhou 311100China research center for Intelligent Optoelectronic Computing Zhejiang LaboratoryHangzhou 311100China International research center for Advanced Photonics College of Optical Science and EngineeringZhejiang UniversityHangzhou 310058China Fiber Optics research center(FORC) Key Laboratory of Optical Fiber Sensing and CommunicationsUniversity of Electronic Science and Technology of ChinaChengdu 611731China

We experimentally demonstrate ultra-high extinction ratio(ER)optical pulse modulation with an electro-optical modulator(EOM)on thin film lithium niobate(TFLN)and its application for fiber optic distributed acoustic sensing(DAS).An interface carrier effect leading to a relaxation-tail response of TFLN EOM is discovered,which can be well addressed by a small compensation component following the main driving *** ultrahigh ER>50 dB is achieved by canceling out the tailed response during pulse modulation using the EOM based on a cascaded Mach–Zehnder interferometer(MZI)*** modulated optical_(√)pulses are then utilized as a probe light for a DAS system,showing a sensitivity up to-62.9 dB·rad∕Hz~2(7 pε/Hz)for 2-km single-mode sensing *** crosstalk suppression of 24.9 dB along the fiber is also obtained when the ER is improved from 20 dB to 50 dB,clearly revealing its importance to the sensing performance.

关键词： modulator pulse interferometer

Numerical investigation of non-uniform temperature fields for proppant and fluid phases in supercritical CO_(2)fracturing

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Particuology 2024年第7期90卷 149-163页

作者： Boyu Liu Jun Yao research center of Multiphase Flow in Porous Media China University of Petroleum(East China)Qingdao 266000China

The non-uniform temperature distribution in supercritical CO_(2)(Sc-CO_(2))fracturing influences the density,viscosity,and volume expansion or shrinkage rate of Sc-CO_(2),impacting proppant *** study presents a coupled computational fluid dynamics-discrete element method and heat transfer model to examine the effects of proppant bed shape and the heat transfers of proppant-wall,proppant-fluid,and fluid-wall on the fluid and proppant temperature *** Sc-CO_(2)volume expansion is assessed under various temperature conditions by evaluating the volume-averaged Sc-CO_(2)*** factors,including proppant size,shape,thermal conductivity,concentration,temperature difference,and injection velocity,are carefully analyzed to elucidate their *** findings elucidate the existence of four distinct zones in the fluid temperature *** zone exhibits different magnitudes of temperature change under diverse conditions and undergoes dynamic transformations with the development of the proppant *** fluid-wall heat transfer and the fluid temperatures in Zones C and D are significantly subject to the fluid injection velocity(governing the heating duration),the temperature difference between fluid and formation(impacting the magnitude of heat flux),and the proppant bed shape(controlling the effective heating area).Additionally,the proppant-wall and proppant-fluid heat transfers determine the temperatures of both the proppant bed and the fluid within Zone B,showing a strong correlation with proppant thermal conductivity,proppant size,injection velocity,and temperature *** proposed coupled model provides valuable insights into the temperature distributions and flow behaviors of temperature-dependent fracturing fluids and proppants.

关键词： CFD-DEM Heat transfer Compressible fluid CO_(2)sequestration Proppant transport

Time-sensitive prediction of NO_(2) concentration in china using an ensemble machine learning model from multi-source data

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Journal of Environmental Sciences 2024年第3期137卷 30-40页

作者： Chenliang Tao Man Jia Guoqiang Wang Yuqiang Zhang Qingzhu Zhang Xianfeng Wang Qiao Wang Wenxing Wang Big Data research center for Ecology and Environment Environment Research InstituteShandong UniversityQingdao 266237China Shandong Provincial Eco-environment Monitoring center Jinan 250101China

Nitrogen dioxide(NO_(2))poses a critical potential risk to environmental quality and public health.A reliable machine learning(ML)forecasting framework will be useful to provide valuable information to support government *** on the data from1609 air quality monitors across china from 2014-2020,this study designed an ensemble ML model by integrating multiple types of spatial-temporal variables and three sub-models for time-sensitive prediction over a wide *** ensemble ML model incorporates a residual connection to the gated recurrent unit(GRU)network and adopts the advantage of Transformer,extreme gradient boosting(XGBoost)and GRU with residual connection network,resulting in a 4.1%±1.0%lower root mean square error over XGBoost for the test *** ensemble model shows great prediction performance,with coefficient of determination of 0.91,0.86,and 0.77 for 1-hr,3-hr,and 24-hr averages for the test results,*** particular,this model has achieved excellent performance with low spatial uncertainty in Central,East,and North china,the major site-dense *** the interpretability analysis based on the Shapley value for different temporal resolutions,we found that the contribution of atmospheric chemical processes is more important for hourly predictions compared with the daily scale predictions,while the impact of meteorological conditions would be ever-prominent for the *** with existing models for different spatiotemporal scales,the present model can be implemented at any air quality monitoring station across china to facilitate achieving rapid and dependable forecast of NO_(2),which will help developing effective control policies.

关键词： Air quality prediction Deep learning Ensemble method Nitrogen dioxide Spatiotemporal covariates

Resveratrol combats chronic diseases through enhancing mitochondrial quality

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Food Science and Human Wellness 2024年第2期13卷 597-610页

作者： Weichu Tao Hu Zhang Xia Jiang Ning Chen Tianjiu research and Development center for Exercise Nutrition and Foods Hubei Key Laboratory of Exercise Training and MonitoringCollege of Sports MedicineWuhan Sports UniversityWuhan 430079China The University Hospital of Wuhan Sports University Wuhan 430079China

Resveratrol(RSV),as a functional food component extracted from natural plants,has been widely studied and recognized in preventing and treating various diseases,with major mechanisms including executing anti-inflammation and anti-oxidation functions,and improving mitochondrial *** diseases as non-communicable diseases are mainly caused by multiple factors,such as physiological decline and dysfunction in the body,and have become a significant challenge on public health *** is worth noting that chronic diseases such as Alzheimer's disease(AD),Parkinson's disease(PD),muscle atrophy,cardiovascular disease,obesity,and cancer are accompanied by abnormal mitochondrial ***,targeted regulation of mitochondria may be a meaningful way to prevent and treat chronic *** evidence has confirmed that RSV is actively involved in regulating mitochondria,and it has become an essential consideration to prevent and treat chronic diseases through targeting mitochondria and improving corresponding *** this article,current studies on RSV to optimize mitochondrial quality for preventing and alleviating chronic disease are systematically summarized,which can provide a theoretical reference for the development of functional foods or drugs to combat chronic diseases.

关键词： Resveratrol Functional food Mitochondrial quality Chronic disease Anti-inflammation Anti-oxidation