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3D robust anisotropic diffusion filtering algorithm for sparse view neutron computed tomography 3D image reconstruction

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Nuclear science and Techniques 2024年第3期35卷 13-29页

作者： Yang Liu Teng-fei Zhu zhi Luo Xiao-ping Ouyang School of Nuclear science and Engineering North China Electric Power UniversityBeijing 102206China State Key Laboratory of Nuclear Resources and Environment East China University of TechnologyNanchang 330013China State Key Laboratory of Intense Pulsed Radiation Simulation and Effect Xi’an 710024China

The most critical part of a neutron computed tomography(NCT) system is the image processing algorithm,which directly affects the quality and speed of the reconstructed *** types of noise in the system can degrade the quality of the reconstructed ***,to improve the quality of the reconstructed images of NCT systems,efficient image processing algorithms must be *** anisotropic diffusion filtering(ADF) algorithm can not only effectively suppress the noise in the projection data,but also preserve the image edge structure information by reducing the diffusion at the image ***,we propose the application of the ADF algorithm for NCT image *** compare the performance of different algorithms in NCT systems,we reconstructed images using the ordered subset simultaneous algebraic reconstruction technique(OS-SART) algorithm with different regular terms as image processing *** the iterative reconstruction,we selected two image processing algorithms,the Total Variation and split Bregman solved total variation algorithms,for comparison with the performance of the ADF ***,the filtered back-projection algorithm was used for comparison with an iterative *** reconstructing the projection data of the numerical and clock models,we compared and analyzed the effects of each algorithm applied in the NCT *** on the reconstruction results,OS-SART-ADF outperformed the other algorithms in terms of denoising,preserving the edge structure,and suppressing *** example,when the 3D Shepp–Logan was reconstructed at 25 views,the root mean square error of OS-SART-ADF was the smallest among the four iterative algorithms,at only *** universal quality index,mean structural similarity,and correlation coefficient of the reconstructed image were the largest among all algorithms,with values of 0.9877,0.9878,and 0.9887,respectively.

关键词： NCT OS-SART Sparse-view Anisotropic diffusion filtering

Megafossils of Betulaceae from the Oligocene of Qaidam Basin and their paleoenvironmental and phytogeographic implications

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Plant Diversity 2024年第1期46卷 101-115页

作者： Tao Yang Jia-Hao Cai Yan-zhi Dai Hong-Yu Chen Lei Han Li zhang Wei-Yu Liang Xu-Jun Li Wen-Jia Li Jing-Yu Wu San-ping Xie De-fei Yan School of Earth sciences and Key Laboratory of Mineral Resources in Western china(Gansu Province) Lanzhou UniversityLanzhou 730000China Key Laboratory of Vertebrate Evolution and Human Origins of chinese academy of sciences Institute of Vertebrate Paleontology and PaleoanthropologyChinese Academy of SciencesBeijing 100044China State Key Laboratory of Palaeobiology and Stratigraphy Nanjing Institute of Geology and Palaeontology and Center for Excellence in Life and PaleoenvironmentChinese Academy of SciencesNanjing 210008China Center for Research and Education on Biological Evolution and Environments School of Earth Sciences and EngineeringNanjing UniversityNanjing 210023China

Understanding the paleoenvironment and phytogeographical history of the Tibetan Plateau,china relies on discovering new plant *** Qaidam Basin has long been regarded as an ideal‘field laboratory’to investigate the paleoclimate and paleobiological evolution of the northern Tibetan ***,fossil angiosperms from the Qaidam Basin are rare,and our knowledge of its paleovegetation is ***,we report fossil leaves and fruits of Betulaceae found from the Oligocene Shangganchaigou Formation of northwestern Qaidam Basin(Huatugou area).Comparative morphological analysis led us to assign the fruits to the Betula subgenus Betula and the leaves to Carpinus *** findings,together with other reported fossil plants from the same locality,reveal a close floristic linkage between the Qaidam Basin and Europe during the *** northern pathway of this floristic exchange may have crossed through the Qaidam Basin during the late *** floristic linkage may have been facilitated by the continuous narrowing of the Turgai Strait and stronger westerlies,which transported moisture and provided favorable climatic ***,fossil plants collected from the Qaidam Basin suggest that during the Oligocene this region had warm and humid deciduous broad-leaf forest,which differs from the region’s modern vegetation and indicates that the Qaidam Basin may have been a suitable region for these plants to flourish and spread during the Oligocene.

关键词： Paleoenvironment Biogeography Betulaceous fossil Qaidam basin Tibetan Plateau Oligocene

Carbon Dioxide Fluxes and Concentrations in a Cotton Field in Northwestern china:Effects of Plastic Mulching and Drip Irrigation

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Pedosphere 2011年第2期21卷 178-185页

作者： LI zhi-Guo Key Laboratory of Oasis Ecology and Desert Environment Xinjiang Institute of Ecology and Geography Chinese Academy ofSciences Urumqi 830011 (China) Graduate University of chinese academy of sciences Beijing 100049 (China) Institute of Soil science Chinese Academy of Sciences Nanjing 210008 (China) Earth System science Interdisciplinary Center University of Maryland College Park MD 20740 (USA)

In northwestern china, there has been a change from traditional cultivation system （TC） with no mulching and flood irrigation to a more modern cultivation system （MC） using plastic film mulching with drip irrigation. A field study was conducted to compare soil ＇C02 concentrations and soil surface COs fluxes between TC and MC systems during a cotton growing season. CO2 concentrations in the soil profile were higher in the MC system （3107-9212μL L-1） than in the TC system （1 275-8994 μL L-1） but the rate of CO2 flux was lower in the MC system. Possible reasons for this included decreased gas diffusion and higher soil moisture due to the mulching cover in the MC system, and the consumption of soil CO2 by weathering reactions. Over the whole cotton growing season, accumulated rates of CO2 flux were 300 and 394 g C m-2 for the MC and TC systems, respectively. When agricultural practices were converted from traditional cultivation to a plastic film mulching system, soil CO2 emissions could be reduced by approximately 100 g C m-2 year-1 in agricultural lands in arid and/or semi-arid areas of northern and northwestern china.

关键词： agricultural practice carbon cycle greenhouse gas emission soil respiration weathering reaction

Stepped-up development of accelerator mass spectrometry method for the detection of ^(60)Fe with the HI-13 tandem accelerator

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Nuclear science and Techniques 2024年第4期35卷 136-143页

作者： Yang zhang Sheng-Quan Yan Ming He Qing-zhang Zhao Wen-Hui zhang Chao-Xin Kan Jian-Ming Zhou Kang-Ning Li Xiao-fei Wang Jian-Cheng Liu Zhao-Hua Peng Zhuo Liang Ai-Ling Li Jian Zheng Qi-Wen Fan Yun-Ju Li You-Bao Wang zhi-Hong Li Yang-ping Shen Ding Nan Wei Nan Yu-Qiang zhang Jia-Ying-Hao Li Jun-Wen Tian Jiang-Lin Hou Chang-Xin Guo zhi-Cheng zhang Ming-Hao Zhu Yu-Wen Chen Yu-Chen Jiang Tao Tian Jin-Long Ma Yi-Hui Liu Jing-Yu Dong Run-Long Liu Mei-Yue-Nan Ma Yong-Shou Chen Wei-ping Liu Bing Guo china Institute of Atomic Energy P.O.Box 275(10)Beijing 102413China College of science Southern University of Science and TechnologyShenzhen 518055China School of Physics Xi’an Jiaotong UniversityXi’an 710049China

The Moon provides a unique environment for investigating nearby astrophysical events such as *** samples retain valuable information from these events,via detectable long-lived“fingerprint”radionuclides such as^(60)*** this work,we stepped up the development of an accelerator mass spectrometry(AMS)method for detecting^(60)Fe using the HI-13tandem accelerator at the china Institute of Atomic Energy(CIAE).Since interferences could not be sufficiently removed solely with the existing magnetic systems of the tandem accelerator and the following Q3D magnetic spectrograph,a Wien filter with a maximum voltage of±60 kV and a maximum magnetic field of 0.3 T was installed after the accelerator magnetic systems to lower the detection background for the low abundance nuclide^(60)Fe.A 1μm thick Si_(3)N_(4) foil was installed in front of the Q3D as an energy *** particle detection,a multi-anode gas ionization chamber was mounted at the center of the focal plane of the ***,an^(60)Fe sample with an abundance of 1.125×10^(-10)was used to test the new AMS *** results indicate that^(60)Fe can be clearly distinguished from the isobar^(60)*** sensitivity was assessed to be better than 4.3×10^(-14)based on blank sample measurements lasting 5.8 h,and the sensitivity could,in principle,be expected to be approximately 2.5×10^(-15)when the data were accumulated for 100 h,which is feasible for future lunar sample measurements because the main contaminants were sufficiently separated.

关键词： Accelerator mass spectrometry Wien filter Isobar separation Supernovae Chang'e-5 lunar samples

Microwave electrometry with Rydberg atoms in a vapor cell using microwave amplitude modulation

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chinese Physics B 2024年第5期33卷 65-74页

作者：郝建海贾凤东崔越王昱寒周飞刘修彬张剑谢锋白金海尤建琦王宇钟志萍 School of Physical sciences University of Chinese Academy of SciencesBeijing 100049China Institute of Nuclear and New Energy Technology Collaborative Innovation Center of Advanced Nuclear Energy TechnologyKey Laboratory of Advanced Reactor Engineering and Safety of Ministry of EducationTsinghua UniversityBeijing 100084China science and Technology on Metrology and Calibration Laboratory Changcheng Institute of Metrology & MeasurementAviation Industry Corporation of ChinaBeijing 100095China CAS Center for Excellence in Topological Quantum Computation University of Chinese Academy of SciencesBeijing 100190China

We have theoretically and experimentally studied the dispersive signal of the Rydberg atomic electromagneticallyinduced transparency(EIT)Autler–Townes(AT)splitting spectra obtained using amplitude modulation of the microwave(MW)electric *** addition to the two zero-crossing points interval△f_(zeros),the dispersion signal has two positive maxima with an interval defined as the shoulder interval△f_(sho),which is theoretically expected to be used to measure a much weaker MW electric *** relationship of the MW field strength E_(MW)and△f_(sho)is experimentally studied at the MW frequencies of 31.6 GHz and 9.2 GHz *** results show that△f_(sho)can be used to characterize the much weaker E_(MW)than that of△f_(zeros)and the traditional EIT–AT splitting interval△f_(m);the minimum E_(MW)measured by△f_(sho)is about 30 times smaller than that by△f_(m).As an example,the minimum E_(MW)at 9.2 GHz that can be characterized by△f_(sho)is 0.056 mV/cm,which is the minimum value characterized by the frequency interval using a vapor cell without adding any auxiliary *** proposed method can improve the weak limit and sensitivity of E_(MW)measured by the spectral frequency interval,which is important in the direct measurement of weak E_(MW).

关键词： quantum sensor Rydberg atoms electromagnetically induced transparency amplitude modulation

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篇章级文本的事件图谱构建与事件抽取方法

计算机工程与设计 2024年第1期45卷 146-152页

作者：张源奔赵一斐赵志浩韩众和张利利谢辉平中国科学院空天信息创新研究院北京100190 中国科学院网络信息体系技术重点实验室北京100190 中国科学院齐鲁空天信息研究院山东济南250000 北京化工大学信息科学与技术学院北京100029

针对篇章级事件抽取任务主要存在的以下3个挑战:模型复杂、事件论元分散以及多事件抽取,提出一种基于异质交互图和有序树的篇章级事件抽取方法DTHIGN。支持以解耦实体抽取部分的方式精简模型的参数;构建面向触发词的篇章级异质交互图,... 详细信息

针对篇章级事件抽取任务主要存在的以下3个挑战:模型复杂、事件论元分散以及多事件抽取,提出一种基于异质交互图和有序树的篇章级事件抽取方法DTHIGN。支持以解耦实体抽取部分的方式精简模型的参数;构建面向触发词的篇章级异质交互图,更全面地对语义进行建模;支持使用基于统一事件模板的树形事件论元抽取方式获得事件论元结果。实验结果表明,该方法能够获得较好的效果并显著降低模型的训练难度。

关键词：深度学习自然语言处理事件图谱事件抽取事件论元抽取异质图图卷积网络

Manipulating the Spatial Structure of Second-Order Quantum Coherence Using Entangled Photons

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chinese Physics Letters 2024年第7期41卷 58-73页

作者：黄双印高菁任志成程子默朱文正薛舒天娄严超刘志峰陈超朱飞杨立平汪喜林王慧田 National Laboratory of Solid State Microstructures and School of Physics Nanjing UniversityNanjing 210093China Collaborative Innovation Center of Advanced Microstructures Nanjing UniversityNanjing 210093China Intelligent Scientific systems Co.Limited Beijing 102208China Center for Quantum sciences and School of Physics Northeast Normal UniversityChangchun 130024China Hefei National Laboratory Hefei 230088China Synergetic Innovation Center of Quantum Information and Quantum Physics University of Science and Technology of ChinaHefei 230026China Collaborative Innovation Center of Extreme Optics Shanxi UniversityTaiyuan 030006China

High-order quantum coherence reveals the statistical correlation of quantum particles. Manipulation of quantum coherence of light in the temporal domain enables the production of the single-photon source, which has become one of the most important quantum resources. High-order quantum coherence in the spatial domain plays a crucial role in a variety of applications, such as quantum imaging, holography, and microscopy. However, the active control of second-order spatial quantum coherence remains a challenging task. Here we predict theoretically and demonstrate experimentally the first active manipulation of second-order spatial quantum coherence,which exhibits the capability of switching between bunching and anti-bunching, by mapping the entanglement of spatially structured photons. We also show that signal processing based on quantum coherence exhibits robust resistance to intensity disturbance. Our findings not only enhance existing applications but also pave the way for broader utilization of higher-order spatial quantum coherence.

关键词： particles quantum spatially

The blocking effect of the sand fences quantified using wind tunnel simulations

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Journal of Mountain science 2020年第10期17卷 2485-2496页

作者： YU Yan-ping zhang Ke-cun AN zhi-shan WANG Tao HU fei Key Laboratory of Desert and Desertification Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhou730000China Dunhuang Gobi and Desert Ecology and Environment Research Station Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesDunhuang736200China University of chinese academy of sciences Beijing100049China

Fences are one of the most effective measures to prevent and control wind-blown sand disasters,and the blocking effect of fences is largely determined by their porosity and height(H).This study employed wind tunnel experiments to measure wind velocities on both sides of wire mesh sand fences with porosities of 75%,63%,56%,36%and heights of 10,5 and 2 *** effects of porosity and height on the blocking effect of the fences were evaluated on the basis of velocity variability,flow field,and the wind velocity reduction *** show that the smaller the porosity,the stronger the blocking *** fence with a porosity of 36%had the strongest windproof efficiency of 0.70 and longest protection range of 9 H,and thus showed the best applicability in preventing and controlling wind-blown sand *** fence with a porosity of 56%showed a windproof efficiency of 0.31 and a protection range of 7 H,which could be considered for ***,fences with porosities of 75%and 63%were not recommended to be adopted,because their windproof efficiency and protection range were very ***,the higher the fence,the stronger the blocking *** highest fence(10 cm)had the longest protection range of 90 cm,which was the best in ***,the 5 and 2 cm fences were almost consistent with 10 cm fence in windproof efficiency,which was still suitable for wind and sand fixation.

关键词： Porous fence Fence height Windproof efficiency Protection range Blocking effect

Representation of Type-2 Fuzzy Sets and Their Operations

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Representation of Type-2 Fuzzy Sets and Their Operations