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基于超材料设计实现C/Co复合材料的超宽带吸收

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红外与毫米波学报 2024年第1期43卷 91-97页

作者：王啸坤过勐超梁磊磊李威唐东明张豹山叶建东杨燚南京大学电子科学与工程学院江苏南京210093

本文通过简单的一步热解法合成了C/Co复合材料,在材料质量填充浓度为35%时,观察到其具有优异的介电频散性能。当材料厚度2.5 mm时,该复合材料在11.2 GHz的最小反射率为-23.7 dB,小于-10 dB的带宽为3.8 GHz。为了进一步提高吸收体的吸波... 详细信息

本文通过简单的一步热解法合成了C/Co复合材料,在材料质量填充浓度为35%时,观察到其具有优异的介电频散性能。当材料厚度2.5 mm时,该复合材料在11.2 GHz的最小反射率为-23.7 dB,小于-10 dB的带宽为3.8 GHz。为了进一步提高吸收体的吸波性能,利用全介质超材料的设计对吸收体的宏观结构进行优化,此方法成功地将小于-10 dB的吸收带宽扩展到15 GHz(7.0~22.0 GHz)。该研究结果可以为高性能微波吸收材料的制备工艺和结构设计提供有价值的参考。

关键词： C/Co化合物微波吸收宽带吸收超材料

Frequency offset estimation based on peak power ratio in LTE system

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The Journal of China Universities of Posts and Telecommunications 2013年第6期20卷 49-54页

作者： WANG Jun GUAN bao LIU shou-yin XIE Wen-wu Department of Electronics and Communication Engineering Central China Normal University Department of LTE Wuhan Hongxin Telecom. Technologies CO.LTD

Orthogonal frequency division multiplexing （OFDM） is one of the key techniques for long term evolution （LTE） system. Frequency offset estimation of OFDM is an essential issue. Especially in the high-speed environment, the frequency offset will become large. Based on the features of LTE uplink physical random access channel （PRACH）, this paper proposes a new frequency offset algorithm by using peak power ratio to enlarge the range of frequency offset estimation. According to the relation between frequency offset and the power delay profile （PDP）, the ratio of the peak power of the PDP at the main window to that at the negative window or positive window is utilized to estimate frequency offset. Simulation results show that the new proposed algorithm extends the estimation range of frequency offset from 1 000 Hz to 1 250 Hz. Meanwhile the accuracy of frequency offset estimation is almost not lost. Particularly in low signal noise ratio （SNR）, the new algorithm has lower mean square error （MSE） compared with traditional phase differential algorithm.

关键词： frequency offset estimation LTE peak power ration PDP

Pressure dynamics of asymmetrically fractured wells in an arbitrarily shaped reservoir

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Journal of Hydrodynamics 2019年第4期31卷 767-777页

作者： Yu-long Zhao bao-chao shan Lie-hui Zhang State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation Southwest Petroleum University Chengdu 610500 China State Key Laboratory^ of Coal Combustion Huazhong University^ of Science and Technology Wuhan 430074 China

A numerical model is established and with the model, the boundary element method and the coupled boundary/finite element method are used to analyze the pressure dynamics of an asymmetrically fractured well in an arbitrarily shaped reservoir. The equation is solved in the Laplace domain, with different flow regimes with or without considerations of the wellbore storage and skin effects. The parameter sensitivity analyses, including the asymmetry factor, the fracture conductivity, the outer boundary shape, the boundary size and the well location, are conducted. The model is validated by comparing the results with those of analytical solutions of two simplified cases and a field case study. The study can be used for the well testing interpretation and the hydraulic fracturing design.

关键词： Asymmetrically fractured well finite conductivity fracture pressure dynamics numerical method arbitrary drainage area

Numerical Investigation on Residual Stresses of the Safe-End/Nozzle Dissimilar Metal Welded Joint in CAP1400 Nuclear Power Plants

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Acta Metallurgica Sinica(English Letters) 2019年第5期32卷 618-628页

作者： Wen-Chao Dong Dian-bao Gao shan-Ping Lu Key Laboratory of Nuclear Materials and Safety Assessment Institute of Metal Research Chinese Academy of Sciences Nuclear Power and Petro-chemical Business Group China First Heavy Industries

The residual stress evolution in a safe-end/nozzle dissimilar metal welded joint of CAP1400 nuclear power plants was investigated in the manufacturing process by finite element simulation. A finite element model, including cladding,buttering, post-weld heat treatment (PWHT) and dissimilar metal multi-pass welding, is developed based on SYSWELD software to investigate the evolution of residual stress in the aforementioned manufacturing process. The results reveal a large tensile axial residual stress, which exists at the weld zone on the inner surface, leads to a high sensitivity to stress corrosion cracking (SCC). PWHT process before dissimilar metal multi-pass welding process has a great in?uence on the magnitude and distribution of final axial residual stress. The risk of SCC on the inner surface of the pipe will increase if PWHT process is not taken into account. Therefore, such crucial thermal manufacturing process such as cladding, buttering and post-weld heat treatment, besides the multi-pass welding process, should be considered in the numerical model in order to accurately predict the distribution and the magnitude of the residual stress.

关键词： CAP1400 nuclear power plants Nozzle Safe-end Dissimilar metal welding Residual stress

Numerical simulation on thermal expansion coefficient of 3D braided C/C composites

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Rare Metals 2014年第1期33卷 99-106页

作者： Chun-Xia Hu He-Jun Li shou-Yang Zhang Yong-shan Song State Key Laboratory of Solidification Processing Carbon/Carbon Composites Research Center Northwestern Polytechnical University School of Mechatronic Engineering Northwestern Polytechnical University

To effectively get the thermal expansion coef- ficient （CTE） of three-dimensional （3D） braided C/C composites and study the variations, a VC＋＋ program with graphical user interfaces was obtained, based on the yam unit model and numerical analysis. With the limited basic properties of carbon fibers and carbon matrix, CTE of 3D braided C/C composites is obtained at 85 ~C. The deviation between the simulated and exl^erimental axial CTE of 3D braided C/C composites is no more than 11%. The effects of different parameters （including the braiding angle of 3D braided preform, the fiber volume fraction and the porosity of 3D braided C/C composites, and the elastic modulus, Poisson＇s ratio and CTEs of carbon fibers and carbon matrix） were analyzed with the program. The results show that the axial CTE of C/C composites decreases with the increase of the braiding angle, the fiber volume fraction, and the porosity of 3D braided C/C composites. The transverse elastic modulus of carbon fibers has the greatest effect on the axial CTE among the studied mechanical parameters, followed by the elastic modulus and Poisson＇s ratio of carbon matrix.

关键词： 3D braided C/C composites Rosen-Hashin equation Axial CTE Simulation

Trust routing algorithm based on multiple decision factor theory in OSPF protocol

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The Journal of China Universities of Posts and Telecommunications 2013年第5期20卷 104-109页

作者： HAN Ting LUO shou-shan ZHU Hong-liang XIN Yang Information Security Center Beijing University of Posts and Telecommunications National Engineering Laboratory for Disaster Backup and Recovery Beijing Safe-Code Technology Co.Ltd.

This paper presents a novel trust model based on multiple decision factor theory （MDFT） and a trust routing algorithm based on MDFT to exactly evaluate routing node trust and establish a trustworthy routing path. MDFT integrates four dimensional trust decision factors including behavior, state, recommend and node liveness to realize an exactly finer-grained trust evaluation. On the basis of MDFT, a trust routing algorithm is presented and validated in open shortest path first （OSPF） protocol. Simulation resuRs show that the algorithm can reflect the routing node trust accurately and has better dynamic response ability. Under the circumstance of existing deceptive nodes, the algorithm has better anti-deception performance and higher attack node detection rate than conventional algorithm.

关键词： routing node trust multiple decision factor theory trust routing algorithm OSPF protocol

基于TASL的急性前循环缺血性脑卒中药物治疗预后因素分析

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磁共振成像 2024年第5期15卷 28-33页

作者：李小雷单春辉赵明娟张晖暴云锋陈英敏河北省疾控预防控制中心石家庄050000 河北省人民医院医学影像科石家庄050051

目的探讨基于血管选择性动脉自旋标记(territorial arterial spin labeling,TASL)技术的急性前循环缺血性脑卒中(acute anterior circulation ischemic stroke,AACIS)药物治疗预后因素的影响性分析。材料与方法回顾性连续纳入确诊AACIS... 详细信息

目的探讨基于血管选择性动脉自旋标记(territorial arterial spin labeling,TASL)技术的急性前循环缺血性脑卒中(acute anterior circulation ischemic stroke,AACIS)药物治疗预后因素的影响性分析。材料与方法回顾性连续纳入确诊AACIS患者136例并根据其治疗后90 d的预后情况分为预后良好(70例)与预后不良(66例)两组。记录责任血管狭窄度、疗前选择性脑血流量(territorial cerebral blood flow,TCBF)、疗后TCBF_(10 d)、相对选择性脑血流量(relative CBF,rTCBF)以及病灶体积,同时收集患者的基线美国国立卫生研究院卒中量表评分(National Institute of Health Stroke Scale,NIHSS)、卒中分型、年龄、性别、身体质量指数等风险因素信息,将上述指标纳入统计模型。对两组间的计量资料使用Mann-Whitney U检验、计数资料使用χ^(2)检验统计其单因素差异性,对具有统计学意义的指标进行多因素联合logisitic回归分析,使用受试者工作特性曲线(receiver operating characteristic curve,ROC)对结果进行诊断效能评判。结果单因素分析中,年龄(Z=16.022)、基线NIHSS评分(Z=148.400)、卒中分型(Z=49.640)、责任血管狭窄度(Z=27.193)、TCBF_(疗前)(Z=693.000)、rTCBF(Z=18.874)及病灶体积(Z=-10.140)差异均有统计学意义(P0.05)。结论在药物保守治疗方法下,患者90 d预后更易受到年龄、基线NIHSS评分、卒中种类、CBF_(疗前)及病灶体积的影响,并不依赖于责任血管的灌注改善情况。

关键词：急性前循环缺血性脑卒中药物治疗磁共振成像血管选择性动脉自旋标记脑血流量

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

Midterm outcomes of percutaneous transluminal septal myocardial ablation in patients with hypertrophic obstructive cardiomyopathy refractory to medication

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Chinese Medical Journal 2006年第13期119卷 1121-1124页

作者： CHEN Shao-liang YE Fei XU Zu-ling LIN Song DUAN bao-xiang DAI Zhen-ling shan shou-jie ZHANG Jun-jie Cardiological Division Nanjing First Hospital of Nanjing MedicalUniversity Nanjing 210006 China Nanjing Heart Centre Nanjing 210006 China

Hypertrophic obstructive cardiomyopathy （HOCM） is a genetic disorder characterized by severe asymmetric hypertrophy of the interventricular septum （IVS） in the absence of any other systemic or cardiac diseases. The predominant abnormal haemodynamics are caused by increased left ventricular outflow tract pressure gradient （LVOTG） and abnormal systolic anterior motion of mitral valve.

关键词： hypertrophic obstructive cardiomyopathy percutaneous transluminal septal myocardial ablation left ventricular outflow tract pressure gradient