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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 Technology Key Laboratory of Human Factors Engineering China Astronaut Research and Training Center

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 exploration. To guarantee the safety of astronauts and the successful accomplishment of missions, it is vital to determine the pose of astronauts during extravehicular activities. This article presents a monocular vision-based pose estimation method of astronauts during extravehicular activities, making full use of the available observation resources. First, the camera is calibrated using objects of known structures, such as the spacesuit backpack or the circular handrail outside the space station. Subsequently, the pose estimation is performed utilizing the feature points on the spacesuit. The proposed methods are validated both on synthetic and semi-physical simulation experiments, demonstrating the high precision of the camera calibration and pose estimation. To further evaluate the performance of the methods in real-world scenarios, we utilize image sequences of Shenzhou-13 astronauts during extravehicular activities. The experiments validate that camera calibration and pose estimation can be accomplished solely with the existing observation resources, without requiring additional complicated equipment. The 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

Wind tunnel investigation of different engine layouts of a blended-wing-body transport

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中国航空学报:英文版 2023年第9期36卷 123-132页

作者： Zheng CUI Guojun LAI qifeng wang Yu LIANG Yihua CAO School of Aeronautic Science and Engineering Beihang UniversityBeijing 100083China COMAC Beijing Aircraft Technology Research Institute Beijing 102211China

A 2%scale,cruising version of a 450-seat class Blended-Wing-Body(BWB)transport was tested in the China Aerodynamic Research and Development Center’s FL-262.4-by-2.4-meter subsonic wind tunnel.The focus of the wind tunnel test was to investigate the aerodynamic performance of the latest BWB transport design,which would also aid in choosing a final engine arrangement in the three most potential engine integration layouts.The wind tunnel model can be tested with and without the nacelle and has three sets of different nacelle/tail integration positions.Computational Fluid Dynamics(CFD)simulations were performed in engine-aircraft integration design to find appropriate nacelle installing parameters of each layout.The comparison of CFD with experimental results shows good agreement.Wind tunnel measurements indicate that the tail-mounted engine layout produces the minimum drag penalty,while the fuselage-mounted engine layout increases drag the most.Experimental pressure measurement illustrates the effect of nacelle integration on the wing-body surface pressure distribution.This experimental and numerical research provides a reference for future BWB Propulsion-Airframe Integration(PAI)design.

关键词： PAI Aerodynamics BWB CFD Civil aviation Engine layout Transport aircraft Wind tunnels

Exploring Antarctic subglacial lakes with RECoverable Autonomous Sonde(RECAS): Design and first field tests

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Science China Technological Sciences 2024年第6期67卷 1866-1878页

作者： SUN YouHong PAVEL Talalay LI YuanSheng YU HaiBin wang DongLiang LI GuoPing XU LiPing GONG Da wang JiXin wang JianHua wang Ting ZHANG Nan wang ZhiGang CHEN YanJi LIU YunChen LI YaZhou PENG ShiLin SHI JianGuang AN ChunLei GE Qun XU Jing NI XiaoKang CUI qifeng JIANG Qiang MIKHAIL Sysoev Yang Yang wang RuSheng WEI XianZhe wang Yu ZHU TianXin DENG ZhiPeng ALEXEY Markov LI Bing FAN XiaoPeng Polar Research Center Jilin University School of Engineering and Technology China University of Geosciences Polar Research Institute of China College of Electronics and Information Hangzhou Dianzi University Aerospace System Engineering Shanghai Nanjing Institute of Astronomical Optics & Technology National Astronomical ObservatoriesChinese Academy of Sciences National Ocean Technology Center

Conducting scientific drilling on subglacial lakes and obtaining samples of subglacial lake water holds great significance in unraveling the formation and evolution of Antarctic subglacial lakes and early Earth's life forms. Despite various approaches to access and directly sample subglacial water and sediments, clean access and exploration of subglacial lakes remain challenging.To address this concern, Jilin University has developed the RECoverable Autonomous Sonde(RECAS) prototype. This technology enables sampling and in-situ detection of subglacial lake water while being isolated from the surface, thus minimizing the risk of pollution. Laboratory tests, including downward and upward drilling, long-running, remote-control, and cold-environment assessments, were conducted to validate the sonde's principle and functionality. During the 38th Chinese National Antarctic Research Expedition, CHINARE(2021–2022 season), the RECAS prototype underwent testing on the flank region of D?lk glacier, 10 km from Zhongshan Station in Antarctica. Three boreholes with depths of 200.3, 183.2, and 133.5 m were successfully drilled, with the refrozen meltwater sealing the boreholes during the process. Approximately 600 mL of melted water samples were collected from each hole. Throughout the drilling tests, all systems of the RECAS prototype performed within the expected ranges.

关键词： subglacial lake thermal drilling water sampling Antarctic autonomous sonde

Prognostic and incremental value of computed tomography-based radiomics from tumor and nodal regions in esophageal squamous cell carcinoma

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Chinese Journal of Cancer Research 2022年第2期34卷 71-82页

作者： Bangrong Cao Kun Mi Wei Dai Tong Liu Tianpeng Xie Qiang Li Jinyi Lang Yongtao Han Lin Peng qifeng wang Radiation Oncology Key Laboratory of Sichuan Province Sichuan Cancer Hospital&InstituteSichuan Cancer CenterSchool of MedicineUniversity of Electronic Science and Technology of ChinaChengdu 610041China Department of Biobank Sichuan Cancer Hospital&InstituteSichuan Cancer CenterSchool of MedicineUniversity of Electronic Science and Technology of ChinaChengdu 610041China Department of Thoracic Surgery Sichuan Cancer Hospital&InstituteSichuan Cancer CenterSchool of MedicineUniversity of Electronic Science and Technology of ChinaChengdu 610041China Department of Medical Imaging Sichuan Cancer Hospital&InstituteSichuan Cancer CenterSchool of MedicineUniversity of Electronic Science and Technology of ChinaChengdu 610041China Department of Radiation Oncology Sichuan Cancer Hospital&InstituteSichuan Cancer CenterSchool of MedicineUniversity of Electronic Science and Technology of ChinaChengdu 610041China

Objective:This study aimed to evaluate the prognostic value of preoperative radiomics and establish an integrated model for esophageal squamous cell cancer(ESCC).Methods:A total of 931 patients were retrospectively enrolled in this study(training cohort,n=624;validation cohort,n=307).Radiomics features were obtained by contrast-enhanced computed tomography(CT)before esophagectomy.A radiomics index was set based on features of tumor and reginal lymph nodes by using the least absolute shrinkage and selection operator(LASSO)Cox regression.Prognostic nomogram was built based on radiomics index and other independent risk factors.The prognostic value was assessed by using Harrell’s concordance index,time-dependent receiver operating characteristics and Kaplan-Meier curves.Results:Twelve radiomic features from tumor and lymph node regions were identified to build a radiomics index,which was significantly associated with overall survival(OS)in both training cohort and validation cohort.The radiomics index was highly correlated with clinical tumor-node-metastasis(cTNM)and pathologic TNM(pTNM)stages,but it demonstrated a better prognostic value compared with cTNM stage and was almost comparable with pTNM stage.Multivariable Cox regression showed that the radiomics index was an independent prognostic factor.An integrated model was constructed based on gender,preoperative serum sodium concentration,pTNM and the radiomics index for clinical usefulness.The integrated model demonstrated discriminatory ability better compared with the traditional clinical-pathologic model and pTNM alone,indicating incremental value for prognosis.Conclusions:CT-based radiomics for primary tumor and reginal lymph nodes was sufficient in predicting OS for patients with ESCC.The integrated model demonstrated incremental value for prognosis and was robust for clinical applications.

关键词： Esophageal squamous cell cancer radiomics lymph node prognosis

Welding depth measurement for different mode lasers using optical coherence tomography

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Chinese Optics Letters 2024年第1期22卷 41-46页

作者：谢冠明王三宏张跃强李由胡彪傅愉于起峰 Institute of Intelligent Optical Measurement and Detection Shenzhen UniversityShenzhen 518060China College of Physics and Optoelectronic Engineering Shenzhen UniversityShenzhen 518060China Shenzhen Sincevision Technology Co. Ltd.Shenzhen 518055China National Key Laboratory of Human Factors Engineering China Astronaut Research and Training CenterBeijing 100094China College of Aerospace Science and Engineering National University of Defense TechnologyChangsha 410073China

Optical coherence tomography(OCT)allows a direct and precise measurement of laser welding depth by coaxially measuring the keyhole depth and can be used for process monitoring and control.When OCT measurement was taken during single-beam laser welding,the keyhole instability of aluminum welding resulted in highly scattered OCT data and complicated the welding depth extraction methods.As a combination of an inner core beam and an outer ring beam,a novel adjustable ring mode(ARM)laser for producing a stable keyhole was applied to the OCT measurement.Different ARM laser power arrangements were conducted on aluminum and copper.The results indicated that the ring beam greatly improved the stability of the core beam-induced keyhole,and smooth welding depth can be extracted from the concentrated OCT data.

关键词： optical coherence tomography adjustable ring mode laser laser welding welding depth

Exosomes in malignant pleural effusions: Sources and applications

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中华医学杂志(英文版) 2024年第11期137卷 2024 Apr 3页

作者： Huang Yueyu wang Jiahui Yao qifeng Yang Xuping Ye Xuemei Liu Junping wang Changchun Zhou Bin Li Shuang Su Bin Mao Weimin Zhao An Zhejiang Cancer Institute Zhejiang Cancer Hospital Hangzhou Institute of Medicine Chinese Academy of Sciences Hangzhou Zhejiang China The Second Clinical Medical College Zhejiang Chinese Medical University Hangzhou Zhejiang China Wenzhou Medical University Wenzhou Zhejiang China Taixing People’s Hospital affiliated Yanzhou University Taizhou Zhejiang China Beijing Key Laboratory for HIV/AIDS Research Beijing Youan Hospital Capital Medical University Beijing China Zhejiang Key Laboratory of Diagnosis & Treatment Technology on Thoracic Oncology (Lung and Esophagus) Hangzhou Zhejiang China Jiangxi Key Laboratory of Tumour Metastasis of Jiangxi Health Commission Jiangxi Cancer Hospital Nanchang Jiangxi China

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基于无人机多光谱遥感的林火监测模型

中南林业科技大学学报 2024年第3期44卷 22-32页

作者：贾志成段棋峰汪东南京林业大学机械电子工程学院江苏南京210037 南京警察学院江苏南京210042

【目的】森林火灾监测多采用卫星和低空热红外遥感对林火进行识别,准确率高,但受限于硬件性能和成本,对基于无人机的多光谱遥感及不同图像传感器比较的林火监测研究较少。【方法】选定山地树林作为试验对象,根据起火点的明火和阴燃两种... 详细信息

【目的】森林火灾监测多采用卫星和低空热红外遥感对林火进行识别,准确率高,但受限于硬件性能和成本,对基于无人机的多光谱遥感及不同图像传感器比较的林火监测研究较少。【方法】选定山地树林作为试验对象,根据起火点的明火和阴燃两种状态,结合树冠状态,分为明火有遮挡、明火无遮挡、阴燃有遮挡、阴燃无遮挡等4种林火状态,以无火场景作为对照,开展森林火灾监测试验,利用无人机分别搭载热红外、多光谱、可见光等图像传感器采集林火图像,分别基于随机森林(RF)、支持向量机(SVM)、反向传播神经网络(BP)3种机器学习算法建立林火监测模型,通过准确率(Accuracy)、精度(Precision)、召回率(Recall)和F1-score进行监测模型性能评估。【结果】综合分析,热红外相机和可见光相机基于支持向量机(SVM)的监测模型准确率最高,多光谱相机基于随机森林(RF)的监测模型准确率最高。热红外相机监测准确率高达100%,多光谱相机接近100%,可见光相机达到85%。综合分析,热红外相机监测准确率最高,多光谱相机次之,可见光相机监测性能最差。多光谱相机可在不同林火状态下较好地替代热红外相机进行监测,可见光相机在不同林火状态下均表现出较差的监测效果。【结论】通过使用机器学习算法进行优化,多光谱相机可在林火监测中有效替代热红外相机,可以显著降低监测成本和丰富林火监测技术手段。

关键词：林火监测多光谱无人机机器学习

Compromised small-world efficiency of structural brain networks in schizophrenic patients and their unaffected parents

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Neuroscience Bulletin 2015年第3期31卷 275-287页

作者： Hao Yan Lin Tian qifeng wang Qiang Zhao Weihua Yue Jun Yan Bing Liu Dai Zhang Peking University Six Hospital Peking University Institute of Mental Health Key Laboratory of Mental Health Ministry of Health (Peking University) LIAMA Center for Computational Medicine National Laboratory of Pattern Recognition Institute of Automation Chinese Academy of Sciences Department of Radiology The Third Hospital Peking University Peking-Tsinghua Center for Life Sciences PKU-IDG/Mc Govern Institute for Brain Research Peking University

Several lines of evidence suggest that efficient information integration between brain regions is disrupted in schizophrenia. Abnormalities in white matter tracts that interconnect brain regions may be directly relevant to this pathophysiological process. As a complex mental disorder with high heritability, mapping abnormalities in patients and their first- degree relatives may help to disentangle the risk factors for schizophrenia. We established a weighted network model of white matter connections using diffusion tensor imaging in 25 nuclear families with schizophrenic probands （19 patients and 41 unaffected parents） and two unrelated groups of normal controls （24 controls matched with patients and 26 controls matched with relatives）. The patient group showed lower global efficiency and local efficiency. The decreased regional efficiency was localized in hubs such as the bilateral frontal cortices, bilateral anterior cingulate cortices, and left precuneus. The global efficiency was negatively correlated with cognition scores derived from a 5-factor model of schizophrenic psychopathology.We also found that unaffected parents displayed decreased regional efficiency in the right temporal cortices, left supplementary motor area, left superior temporal pole, and left thalamus. The global efficiency tended to be lower in unaffected parents. Our data suggest that （1） the global efficiency loss in neuroanatomical networks may be associated with the cognitive disturbances in schizophrenia; and （2） genetic vulnerability to schizophrenia may influence the anatomical organization of an individual＇s brain networks.

关键词： network analysis diffusion tensorimaging tractography white matter small-worldarchitecture

基于频率前馈补偿的储能VSG并网有功响应优化策略

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太阳能学报 2024年第2期45卷 236-243页

作者：兰才华石荣亮王国斌周其锋刘维莎桂林理工大学机械与控制工程学院桂林541006

分析现有基于电磁功率前馈补偿的暂态阻尼方案,该方案可有效抑制储能虚拟同步机(VSG)并网有功的动态振荡,但会因降低其惯量支撑能力而存在频率过冲风险。为此,提出一种基于频率前馈补偿的暂态阻尼优化策略。该策略在不影响储能VSG惯量... 详细信息

分析现有基于电磁功率前馈补偿的暂态阻尼方案,该方案可有效抑制储能虚拟同步机(VSG)并网有功的动态振荡,但会因降低其惯量支撑能力而存在频率过冲风险。为此,提出一种基于频率前馈补偿的暂态阻尼优化策略。该策略在不影响储能VSG惯量响应性能的前提下,可有效抑制其并网有功的动态振荡,既能大大减小有功超调,又不会引起频率过冲。最后,建立储能VSG并网系统的Matlab仿真模型与实验平台,仿真与实验测试对比结果验证了所提策略的有效性与优越性。

关键词：虚拟同步机虚拟惯量储能下垂特性暂态阻尼动态振荡