检索结果-南通市图书馆

New evidence for lack of CMB power on large scales

在线全文

学校读者我要写书评

暂无评论

Science china(physics,Mechanics & Astronomy) 2010年第3期53卷 567-570页

作者： liu hao1 & li tipei1,2,3 1 key laboratory of particle astrophysics, institute of high energy physics, chinese academy of sciences, beijing 100049, china 2 Department of physics & Center for astrophysics, Tsinghua University, beijing 100084, china 3 Department of Engineering physics & Center for astrophysics, Tsinghua University, beijing 100084, china key laboratory of particle astrophysics Institute of High Energy Physics Chinese Academy of Sciences Beijing China Department of physics & Center for astrophysics Tsinghua University Beijing China Department of Engineering physics & Center for astrophysics Tsinghua University Beijing China

A digitalized temperature map is recovered from the first light sky survey image published by the Planck team, from which an angular power spectrum of the cosmic microwave background (CMB) is derived. The amplitudes of the low multipoles (low-l) measured from the preliminary Planck power spectrum are significantly lower than those reported by the WMAP team. Possible systematical effects are far from enough to explain the observed low-l differences.

关键词： cosmology cosmic microwave background data analysis

Inconsistency between WMAP data and released map

在线全文

学校读者我要写书评

暂无评论

chinese Science Bulletin 2010年第10期55卷 907-909页

作者： liu hao1 & li tipei1,2,3 1 key laboratory of particle astrophysics,institute of high energy physics,chinese academy of sciences,beijing 100049,china 2 Department of physics & Center for astrophysics,Tsinghua University,beijing 100084,china 3 Department of Engineering physics & Center for astrophysics,Tsinghua University,beijing 100084,china key laboratory of particle astrophysics Institute of High Energy Physics Chinese Academy of Sciences Beijing China Department of physics & Center for astrophysics Tsinghua University Beijing China Department of Engineering physics & Center for astrophysics Tsinghua University Beijing China

A remarkable inconsistency between the calibrated differential time-ordered data (TOD) of the Wilkinson Microwave Anisotropy Probe (WMAP) mission,which is the input for map-making,and the cosmic microwave background (CMB) temperature maps published by the WMAP team is revealed,indicating that there must exist a serious problem in the map making routine of the WMAP *** inconsistency is easy to be confirmed without the use of WMAP map-making *** view of the importance of this issue for cosmology study,we invite readers to check it by themselves.

关键词：威尔金森微波各向异性探测器 WMAP 地图制作宇宙微波背景有序数据制作软件 TOD CMB

Implementation of a particle-in-cell method for the energy solver in 3D spherical geodynamic modeling

在线全文

学校读者我要写书评

暂无评论

Earth and Planetary physics 2024年第3期8卷 549-563页

作者： hao Dong ZeBin Cao liJun liu YanChong li SanZhong li liMing Dai XinYu li Frontiers Science Center for Deep Ocean Multispheres and Earth System Key Laboratory of Submarine Geosciences and Prospecting TechniquesMinistry of Education and College of Marine GeosciencesOcean University of ChinaQingdao 266100China State key laboratory of lithospheric Evolution Institute of Geology and GeophysicsChinese Academy of SciencesBeijing 100029China laboratory for Marine Geology Laoshan LaboratoryQingdao 266237China Department of Earth Science&Environmental Change University of Illinois at Urbana-ChampaignUrbanaIL 61801USA laboratory of Seismology and physics of Earth’s Interior School of Earth and Space SciencesUniversity of Science and Technology of ChinaHefei 230026China

The thermal evolution of the Earth’s interior and its dynamic effects are the focus of Earth ***,the commonly adopted grid-based temperature solver is usually prone to numerical oscillations,especially in the presence of sharp thermal gradients,such as when modeling subducting slabs and rising *** phenomenon prohibits the correct representation of thermal evolution and may cause incorrect implications of geodynamic *** examining several approaches for removing these numerical oscillations,we show that the Lagrangian method provides an ideal way to solve this *** this study,we propose a particle-in-cell method as a strategy for improving the solution to the energy equation and demonstrate its effectiveness in both one-dimensional and three-dimensional thermal problems,as well as in a global spherical simulation with data *** have implemented this method in the open-source finite-element code CitcomS,which features a spherical coordinate system,distributed memory parallel computing,and data assimilation algorithms.

关键词： numerical oscillation overshooting and undershooting particle-in-cell method three-dimensional spherical geodynamic modeling energy solver finite element method

Normalized glandular dose coefficients for digital breast tomosynthesis using detailed chinese breast models

在线全文

学校读者我要写书评

暂无评论

Nuclear Science and Techniques 2024年第5期35卷 42-59页

作者： Jia-hao Wang Rui Qiu An-Kang Hu Ye-Qi liu Zhen Wu Hui Zhang Jun-li li Department of Engineering physics Tsinghua UniversityBeijing 100084China key laboratory of particle and Radiation Imaging Ministry of EducationTsinghua UniversityBeijing 100084China Joint institute of Tsinghua University Nuctech Company Limited BeijingBeijing 100084China

The rise in breast cancer diagnoses among chinese women has necessitated the use of X-ray breast screening,which carries a radiation *** study aimed to provide a dosimetry protocol for the chinese female population to replace the traditional standard that utilizes simplified breast models,for the accurate estimation of the mean glandular dose of a patient undergoing digital breast tomosynthesis(DBT).The first set of detailed chinese female breast models and representative breast parameters was *** backscatter radiation and computational efficiency,we improved the combination of these models and the chinese reference adult female whole-body voxel *** acquisition for four commercial DBT systems that are widely employed in china was simulated using the Monte Carlo method to obtain the normalized glandular dose coefficients of DBT(D_(gN)^(DBT))and the glandular depth dose(D_(g)^(dep)(z))for different breast characteristics and X-ray *** calculated a series of D_(gN)^(DBT) values for breasts with different percentage mass glandularities(5%,25%,50%,75%,and 100%)and compressed breast thicknesses(2,3,4,5,6,and 7 cm)at various tube potentials(25,28,30,32,35,and 49 kV)and target/filter combinations(W/Rh,W/Al,Mo/Mo,Rh/Rh,and Rh/Ag).The parameter dependence of the breast characteristics and beam conditions on D_(gN)^(DBT) in detailed breast models was *** D_(gN)^(DBT) results were 14.6-51.0%lower than those of the traditional dosimetry standard in *** difference in D_(gN)^(DBT) was mainly due to a decrease in the depth of the main energy deposition area caused by the glandular distribution along the depth *** results obtained in this study may be used to improve breast dosimetry in china and provide more detailed information on risk assessment during DBT.

关键词： Digital breast tomosynthesis Normalized glandular dose coefficients Detailed breast model Monte Carlo simulation

Nondestructive technique for identifying nuclides using neutron resonance transmission analysis at CSNS Back-n

在线全文

学校读者我要写书评

暂无评论

Nuclear Science and Techniques 2024年第1期35卷 178-187页

作者： Sheng-Da Tang Yong-hao Chen Jing-Yu Tang Rui-Rui Fan Qiang li Gong li Dong liu Zheng-Yao Jin Xing-Zhu Cui Tian-Xiang Chen Yi-Wei Yang Rong liu Han Yi Yang li Zhen Yang Qi An hao-Fan Bai Jiang-Bo Bai Jie Bao Ping Cao Qi-Ping Chen Zhen Chen Zeng-Qi Cui An-Chuan Fan Chang-Qing Feng Fan-Zhen Feng Ke-Qing Gao Min-hao Gu Chang-Cai Han Zi-Jie Han Guo-Zhu He Yong-Cheng He Yang Hong Yi-Wei Hu Han-Xiong Huang Wei-Hua Jia hao-yu Jiang Wei Jiang Zhi-jie Jiang ling Kang Bo li Chao li Jia-Wen li Xiao li Jie liu Shu-Bin liu Guang-Yuan Luan Chang-Jun Ning Bin-Bin Qi Jie Ren Zhi-Zhou Ren Xi-Chao Ruan Zhao-Hui Song Kang Sun Zhi-Xin Tan li-Jiao Wang Peng-Cheng Wang Zhao-Hui Wang Zhong-Wei Wen Xiao-Guang Wu Xuan Wu li-Kun Xie Yong-Ji Yu Guo-Hui Zhang lin-hao Zhang Mo-Han Zhang Qi-Wei Zhang Xian-Peng Zhang Yu-liang Zhang Yue Zhang Zhi-Yong Zhang Mao-Yuan Zhao Lu-Ping Zhou Zhi-hao Zhou Ke-Jun Zhu Sino-French institute of Nuclear Engineering and Technology Sun Yat-sen UniversityZhuhai 519082China institute of high-energy physics Chinese Academy of Sciences(CAS)Beijing 100049China Spallation Neutron Source Science Center Dongguan 523803China School of Nuclear Science and Technology University of Science and Technology of ChinaHefei 230026China State key laboratory of particle Detection and Electronics University of Science and Technology of ChinaHefei 230026China State key laboratory of particle Detection and Electronics Institute of High Energy PhysicsChinese Academy of SciencesBeijing 100049China USTC Archaeometry laboratory University of Science and Technology of ChinaHefei 230026China institute of Nuclear physics and Chemistry China Academy of Engineering PhysicsMianyang 621900China Department of Modern physics University of Science and Technology of ChinaHefei 230026China State key laboratory of Nuclear physics and Technology School of PhysicsPeking UniversityBeijing 100871China key laboratory of Nuclear Data China Institute of Atomic EnergyBeijing 102413China Northwest institute of Nuclear Technology Xi’an 710024China University of chinese academy of sciences Beijing 100049China

Nondestructive and noninvasive neutron assays are essential applications of neutron *** resonance transmission analysis(NRTA)is a powerful nondestructive method for investigating the elemental composition of an *** back-streaming neutron line(Back-n)is a newly built time-of-flight facility at the china Spallation Neutron Source(CSNS)that provides neutrons in the eV to 300 MeV range.A feasibility study of the NRTA method for nuclide identification was conducted at the CSNS Back-n via two test *** results demonstrate that it is feasible to identify different elements and isotopes in samples using the NRTA method at *** study reveals its potential future applications.

关键词： CSNS White neutron beam NRTA Nuclide identification Nondestructive method

Design and prototyping of the readout electronics for the transition radiation detector in the high energy cosmic radiation detection facility

在线全文

学校读者我要写书评

暂无评论

Nuclear Science and Techniques 2024年第4期35卷 189-199页

作者： Jie-Yu Zhu Yang-Zhou Su Hai-Bo Yang Fen-Hua Lu Yan Yang Xi-Wen liu Ping Wei Shu-Cai Wan hao-Qing Xie Xian-Qin li Cong Dai Hui-Jun Hu Hong-Bang liu Shu-Wen Tang Cheng-Xin Zhao institute of Modern physics Chinese Academy of SciencesLanzhou 730000China School of Nuclear Science and Technology University of Chinese Academy of SciencesBeijing 100049China Guangxi key laboratory for Relativistic astrophysics School of Physical Science and TechnologyGuangxi UniversityNanning 530004China

The high energy cosmic-radiation detection(HERD)facility is planned to launch in 2027 and scheduled to be installed on the china Space *** serves as a dark matter particle detector,a cosmic ray instrument,and an observatory for high-energy gamma rays.A transition radiation detector placed on one of its lateral sides serves dual purpose,(ⅰ)calibrating HERD's electromagnetic calorimeter in the TeV energy range,and(ⅱ)serving as an independent detector for high-energy gamma *** this paper,the prototype readout electronics design of the transition radiation detector is demonstrated,which aims to accurately measure the charge of the anodes using the SAMPA application specific integrated circuit *** electronic performance of the prototype system is evaluated in terms of noise,linearity,and *** the presented design,each electronic channel can achieve a dynamic range of 0–100 fC,the RMS noise level not exceeding 0.15 fC,and the integral nonlinearity was<0.2%.To further verify the readout electronic performance,a joint test with the detector was carried out,and the results show that the prototype system can satisfy the requirements of the detector's scientific goals.

关键词： HERD Dark matter particle detection TRD Readout electronics SAMPA Data acquisition Performance test

Research on the knee region of cosmic ray by using a novel type of electron-neutron detector array

在线全文

学校读者我要写书评

暂无评论

Frontiers of physics 2024年第4期19卷 13-24页

作者： Bing-Bing li Xin-Hua Ma Shu-Wang Cui hao-Kun Chen Tian-Lu Chen Danzengluobu Wei Gao Hai-Bing Hu Denis Kuleshov Kirill Kurinov Hu liu Mao-Yuan liu Ye liu Da-Yu Peng Yao-Hui Qi Oleg Shchegolev Yuri Stenkin li-Qiao Yin Heng-Yu Zhang liang-Wei Zhang College of physics Hebei Normal UniversityShijiazhuang 050024China key laboratory of particle astrophysics Institute of High Energy PhysicsChinese Academy of SciencesBeijing 100049China TIANFU Cosmic Ray Research Center Chengdu 610000China College of Science Tibet UniversityLhasa 850000China key laboratory of Comic Rays Ministry of EducationTibet UniversityLhasa 850000China institute for Nuclear Research of the Russian academy of sciences Moscow 117312Russia School of Physical Science and Technology Southwest Jiaotong UniversityChengdu 610031China School of Management Science and Engineering Hebei University of Economics and BusinessShijiazhuang 050061China Moscow institute of physics and Technology Moscow 141700Russia

By accurately measuring composition and energy spectrum of cosmic ray,the origin problem of so called“knee”region(energy>one PeV)can be ***,up to the present,the results of the spectrum in the knee region obtained by several previous experiments have shown obvious differences,so they cannot give effective evidence for judging the theoretical models on the origin of the ***,the Large high Altitude Air Shower Observatory(LHAASO)has reported several major breakthroughs and important results in astro-particle physics *** on its advantages of wide-sky survey,high altitude location and large area detector arrays,the research content of LHAASO experiment mainly includes ultra high-energy gamma-ray astronomy,measurement of cosmic ray spectra in the knee region,searching for dark matter and new phenomena of particle physics at higher *** electron and thermal neutron detector(EN-Detector)is a new scintillator detector which applies thermal neutron detection technology to measure cosmic ray extensive air shower(EAS).This technology is an extension of *** EN-Detector Array(ENDA)can highly efficiently measure thermal neutrons generated by secondary hadrons so called“skeleton”of *** this paper,we perform the optimization of ENDA configuration,and obtain expectations on the ENDA results,including thermal neutron distribution,trigger efficiency and capability of cosmic ray composition *** obtained real data results are consistent with those by the Monte Carlo simulation.

关键词： cosmic ray EAS knee region LHAASO ENDA

Application of deep learning methods combined with physical background in wide field of view imaging atmospheric Cherenkov telescopes

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Nuclear Science and Techniques 2024年第4期35卷 208-220页

作者： Ao-Yan Cheng hao Cai Shi Chen Tian-Lu Chen Xiang Dong You-liang Feng Qi Gao Quan-Bu Gou Yi-Qing Guo Hong-Bo Hu Ming-Ming Kang Hai-Jin li Chen liu Mao-Yuan liu Wei liu Fang-Sheng Min Chu-Cheng Pan Bing-Qiang Qiao Xiang-li Qian Hui-Ying Sun Yu-Chang Sun Ao-Bo Wang Xu Wang Zhen Wang Guang-Guang Xin Yu-Hua Yao Qiang Yuan Yi Zhang School of physics and Technology Wuhan UniversityWuhan 430072China School of physics and Astronomy Yunnan UniversityKunming 650091China Ministry of Education The Key Laboratory of Cosmic Rays(Tibet University)Lhasa 850000China key laboratory of particle astrophysics Institute of High Energy PhysicsChinese Academy of SciencesBeijing 100049China University of chinese academy of sciences 19 A Yuquan RoadShijingshan DistrictBeijing 100049China College of physics Sichuan UniversityChengdu 610064China School of Intelligent Engineering Shandong Management UniversityJinan 250357China Tsung‑Dao Lee institute Shanghai Jiao Tong UniversityShanghai 200240China Suzhou Aerospace Information Research institute Suzhou 215123China College of physics Chongqing UniversityNo.55 Daxuecheng South RoadHigh‑tech DistrictChongqing 401331China key laboratory of Dark Matter and Space Astronomy Purple Mountain ObservatoryChinese Academy of SciencesNanjing 210008China

The high Altitude Detection of Astronomical Radiation(HADAR)experiment,which was constructed in Tibet,china,combines the wide-angle advantages of traditional EAS array detectors with the high-sensitivity advantages of focused Cherenkov *** objective is to observe transient sources such as gamma-ray bursts and the counterparts of gravitational *** study aims to utilize the latest AI technology to enhance the sensitivity of HADAR *** datasets and models with distinctive creativity were constructed by incorporating the relevant physical theories for various *** models can determine the type,energy,and direction of the incident particles after careful *** obtained a background identification accuracy of 98.6%,a relative energy reconstruction error of 10.0%,and an angular resolution of 0.22°in a test dataset at 10 *** findings demonstrate the significant potential for enhancing the precision and dependability of detector data analysis in astrophysical *** using deep learning techniques,the HADAR experiment’s observational sensitivity to the Crab Nebula has surpassed that of MAGIC and *** energies below 0.5 TeV and remains competitive with conventional narrow-field Cherenkov telescopes at higher *** addition,our experiment offers a new approach for dealing with strongly connected,scattered data.

关键词： VHE gamma-ray astronomy HADAR Deep learning Convolutional neural networks

在线全文

学校读者我要写书评

暂无评论

车用先进高强钢表面分析及胶接性能研究

表面技术 2024年第4期53卷 211-219页

作者：邵蓉黎敏刘永壮曹建平郝玉林蔡宁李学涛首钢集团有限公司技术研究院北京100043 绿色可循环钢铁流程北京市重点实验室北京100043

目的明确不同先进高强钢表面氧化物形貌、成分及含量对胶接性能的影响规律。方法本研究采用白光干涉仪、扫描电子显微镜(SEM)及透射电子显微镜(TEM)观察高强钢表面形貌,通过金相显微镜及X射线衍射仪(XRD)分析其显微组织及物相,采用直读... 详细信息

目的明确不同先进高强钢表面氧化物形貌、成分及含量对胶接性能的影响规律。方法本研究采用白光干涉仪、扫描电子显微镜(SEM)及透射电子显微镜(TEM)观察高强钢表面形貌,通过金相显微镜及X射线衍射仪(XRD)分析其显微组织及物相,采用直读光谱仪、辉光光谱仪(GDS)以及X射线光电子能谱仪(XPS)表征高强钢表面特征元素及氧化物种类。结合接触角测试对比不同高强钢表面润湿性,并分析总结高强钢表面成分对胶接性能的影响规律。结果DH780表面以膜层状Al基氧化物为主,DP980、DP1180以及CP1180表面以Si、Mn、Cr颗粒状氧化物为主。其中DH780的表面润湿性最差,自由能最小。CP1180钢表面具有最少的氧化物含量及最小的颗粒尺寸,其表面润湿性最好,表面自由能最高。DP钢随强度提高,表面氧化物含量增加,润湿性降低。对于同种焊装胶,DH780胶接剪切强度最小,CP1180剪切强度最大。结论高强钢表面氧化物富集对表面润湿性及表面自由能具有重要影响,尤其Al基氧化物的存在会明显降低胶接接头的剪切强度。一方面是氧化物导致表面自由能降低,黏附功下降,另一方面氧化物会阻止胶中极性基团与基体表面形成强化学键,而更多地形成氢键。Al基氧化物由于呈薄膜状覆盖于高强钢表面,故对胶接性能的影响最大。

关键词：先进高强钢表面成分润湿性胶接性能