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一种基于ResNet的雷达弱小目标检测方法

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无线电工程 2024年第7期54卷 1652-1659页

作者：邱明劼张鹏汪圣利南京电子技术研究所江苏南京210039 中国电子科技集团公司电子科学研究院北京100041

为了解决恒虚警率(Constant False Alarm Rate,CFAR)检测算法对雷达弱小目标检测困难的问题,研究了基于卷积神经网络(Convolutional Neural Network,CNN)的目标检测方法。充分利用神经网络在特征提取上的优良性能,提出了一种基于残差网... 详细信息

为了解决恒虚警率(Constant False Alarm Rate,CFAR)检测算法对雷达弱小目标检测困难的问题,研究了基于卷积神经网络(Convolutional Neural Network,CNN)的目标检测方法。充分利用神经网络在特征提取上的优良性能,提出了一种基于残差网络(Residual Network,ResNet)块的雷达弱小目标检测方法。突破了传统方法仅利用幅度信息进行目标检测的框架,充分挖掘雷达回波数据中目标的相位特征作为神经网络目标分类检测的依据。经实验验证,所提出的方法在目标回波信噪比仅有-7 dB情况下,仍可实现50%以上的发现概率,并且随着信噪比的降低,所提方法的优异性越发明显。

关键词：恒虚警率检测残差网络弱小目标检测

Alleviatory effect of rare earth micro-fertilizer on photosystemⅡ(PSⅡ)photoinhibition in Pseudostellaria heterophylla leaves at photosynthetic midday depression

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Journal of Rare Earths 2022年第7期40卷 1156-1164页

作者： Yingli Ma Tao Wang Yinfeng Xie Qian Lv Lingling qiu Co-Innovation Center for Sustainable Forestry in Southern China College of Biology and the EnvironmentNanjing Forestry UniversityNanjing 210037China Jiangsu Key Laboratory for the Research and Utilization of Plant Resources Institute of BotanyJiangsu Province and Chinese Academy of Sciences(Nanjing Botanical Garden Mem.Sun Yat-Sen)Nanjing 210014China

In order to explo re the mitigatory mechanism of rare earths on the midday depression of photosynthesis,this study used fast-phase chlorophyll fluorescence technology combined with an antioxidant enzyme system to analyze the effects of lanthanum and cerium on the photosystemⅡ(PSⅡ)function of Pseudostellaria heterophylla leaves at *** results show that the maximum photochemical efficiency(F_(v)/F_(m))and the photosynthetic performance index(PI_(ABS))of *** leaves during the photo synthetic noon-break are only 0.73 and 0.86,*** leaves of *** show obvious *** application of two rare earth fertilizers promotes the light energy absorption,capture,conversion,and electron transfer efficiencies of PSⅡin the *** leaves and alleviates the photoinhibition caused by excess excitation ***,the effect of lanthanum is better than that of *** the fertilization groups,*** leaves show higher PSⅡphotochemical *** protects the oxygen-evolving complex(OEC)activity of ***,thus reducing oxidative damage to the chloroplasts and preventing the dissociation of the thylakoids to maintain the normal physiological functioning of PSⅡ,thereby reducing the degree of ***,fertilization increases the electron transfer ability from Q_(A) to Q_(B) on the PSⅡelectron receptor side of *** analysis shows that the fluorescence parameters V_(L),V_(K),and V_(J) are significantly negatively correlated with antioxidant enzyme activity and are significantly positively correlated with malondialdehyde content,relative electric conductivity and reactive oxygen species(ROS),which further indicates that rare earths can enhance the ROS scavenging system in plants and reduce the degree of membrane lipid peroxidation and plasma membrane damage,thereby maintaining the structure and function of the OEC on the donor side of PSⅡ,increasing the elect

关键词： Pseudostellaria heterophylla Rare earths Photoinhibition JIP-test Antioxidant enzyme system

Cascaded Sliding-mode Observer and Its Applications in Output Feedback Control Part I:Observer Design and Stability Analysis

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CSEE Journal of Power and Energy Systems 2021年第2期7卷 295-306页

作者： Tianhao Wen Yang Liu Q.H.Wu Luonan qiu School of Electric Power Engineering South China University of TechnologyGuangzhou 510640China

This paper proposes a cascaded sliding-mode observer for systems with high relative degree and studies its applications in output feedback controller *** part I,the working principle and parameter design of the proposed observer are discussed in *** is proved that,within a sufficiently short period of time,the states of the proposed observer will reach the intersection of all the sliding *** sliding surfaces,the observation error of the proposed observer will converge to sufficiently small *** with traditional high-gain observers,the proposed observer has smaller gain *** addition,the peaking-phenomenon occurred in the proposed observer is less ***,the proposed observer has a convergence rate of observation error as fast as that of traditional high-gain *** studies are carried out on a fifth-order system to verify the properties of the proposed observer.

关键词： Sliding-mode observer stability output feedback control

Evaluation of liquefaction-induced lateral displacement using Bayesian belief networks

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Frontiers of Structural and Civil Engineering 2021年第1期15卷 80-98页

作者： Mahmood AHMAD Xiao-Wei TANG Jiang-Nan qiu Feezan AHMAD State Key Laboratory of Coastal and Offshore Engineering Dalian University of TechnologyDalian 116024China Department of Civil Engineering University of Engineering and Technology Peshawar(Bannu Campus)Bannu 28100Pakistan Faculty of Management and Economics Dalian University of TechnologyDalian 116024China Department of Civil Engineering Abasyn UniversityPeshawar 25000Pakistan

Liquefaction-induced lateral displacement is responsible for considerable damage to engineered structures during major ***,an accurate estimation of lateral displacement in liquefaction-prone regions is an essential task for geotechnical experts for sustainable *** paper presents a novel probabilistic framework for evaluating liquefaction-induced lateral displacement using the Bayesian belief network(BBN)approach based on an interpretive structural modeling *** BBN models are trained and tested using a wide-range casehistory records *** two BBN models are proposed to predict lateral displacements for free-face and sloping ground *** predictive performance results of the proposed BBN models are compared with those of frequently used multiple linear regression and genetic programming *** results reveal that the BBN models are able to learn complex relationships between lateral displacement and its influencing factors as cause-effect relationships,with reasonable *** study also presents a sensitivity analysis to evaluate the impacts of input factors on the lateral displacement.

关键词： Bayesian belief network seismically induced soil liquefaction interpretive structural modeling lateral displacement

Flexural and longitudinal shear performance of precast lightweight steel-ultra-high performance concrete composite beam

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Frontiers of Structural and Civil Engineering 2023年第5期17卷 704-721页

作者： Ze MO Jiangrui qiu Hanbin XU Lanlan XU Yuqing HU Key Laboratory of Concrete and Prestressed Concrete Structures of Ministry of Education School of Civil EngineeringSoutheast UniversityNanjing 211189China College of Civil and Transportation Engineering Hohai UniversityNanjing 210024China School of Civil Engineering Jiangsu Open UniversityNanjing 210036China

In this study,the flexural and longitudinal shear performances of two types of precast lightweight steel–ultra-high performance concrete(UHPC)composite beams are investigated,where a cluster UHPC slab(CUS)and a normal UHPC slab(NUS)are connected to a steel beam using headed studs through discontinuous shear pockets and full-length shear pockets,*** show that the longitudinal shear force of the CUS is greater than that of the NUS,whereas the interfacial slip of the former is *** to its better integrity,the CUS exhibits greater flexural stiffness and a higher ultimate bearing capacity than the *** further optimize the design parameters of the CUS,a parametric study is conducted to investigate their effects on the flexural and longitudinal shear *** square shear pocket is shown to be more applicable for the CUS,as the optimal spacing between two shear pockets is 650 ***,a design method for transverse reinforcement is proposed;the transverse reinforcement is used to withstand the splitting force caused by studs in the shear pocket and prevent the UHPC slab from *** to calculation results,the transverse reinforcement can be canceled when the compressive strength of UHPC is 150 MPa and the volume fraction of steel fiber exceeds 2.0%.

关键词： precast steel-UHPC composite beam flexural performance longitudinal shear performance parametric study transverse reinforcement ratio

A Footpad Structure with Reusable Energy Absorption Capability for Deep Space Exploration Lander:Design and Analysis

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Chinese Journal of Mechanical Engineering 2023年第4期36卷 257-270页

作者： Weiyuan Dou Xiaohang qiu Zhiwei Xiong Yanzhao Guo Lele Zhang School of Mechanical Electronic and Control EngineeringBeijing Jiaotong UniversityBeijing 100044China National International Science and Technology Cooperation Base on Railway Vehicle Operation Engineering Beijing Jiaotong UniversityBeijing 100044China China Academy of Space Technology Beijing 100094China

The footpad structure of a deep space exploration lander is a critical system that makes the initial contact with the ground,and thereby plays a crucial role in determining the stability and energy absorption characteristics during the impact *** conventional footpad is typically designed with an aluminum honeycomb structure that dissipates energy through plastic ***,its effectiveness in providing cushioning and energy absorption becomes significantly compromised when the structure is crushed,rendering it unusable for reusable landers in the *** study presents a methodology for designing and evaluating structural energy absorption systems incorporating recoverable strain constraints of shape memory alloys(SMA).The topological configuration of the energy absorbing structure is derived using an equivalent static load method(ESL),and three lightweight footpad designs featuring honeycomb-like Ni-Ti shape memory alloys structures and having variable stiffness skins are *** verify the accuracy of the numerical modelling,a honeycomb-like structure subjected to compression load is modeled and then compared with experimental ***,the influence of the configurations and thickness distribution of the proposed structures on their energy absorption performance is comprehensively evaluated using finite element *** results demonstrate that the proposed design approach effectively regulates the strain threshold to maintain the SMA within the constraint of maximum recoverable strain,resulting in a structural energy absorption capacity of 362 J/kg with a crushing force efficiency greater than 63%.

关键词： Deep space exploration lander Footpad Shape memory alloy(SMA) Reusable energy absorption structure Design method

VC和Mo_(2)C对微波烧结WC-Ni_(3)Al基硬质合金组织及力学性能的影响

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湖南科技大学学报（自然科学版） 2024年第2期39卷 102-108页

作者：韩旭唐思文卢继刘骞邱新义杨植富湖南科技大学机械设备健康维护湖南省重点实验室湖南湘潭411201 湖南科技大学深海深地矿产资源开发技术与装备教育部工程研究中心湖南湘潭411201 湖南科技大学难加工材料高效精密加工湖南省重点实验室湖南湘潭411201

采用微波烧结制备添加不同含量VC, Mo_(2)C的WC-Ni_(3)Al基硬质合金,研究添加VC和Mo_(2)C对其组织和力学性能的影响.添加VC和Mo_(2)C均可以抑制WC的溶解-析出过程,从而细化WC晶粒,同时也使黏结相Ni3Al的分布变得均匀,其中VC细化晶粒的... 详细信息

采用微波烧结制备添加不同含量VC, Mo_(2)C的WC-Ni_(3)Al基硬质合金,研究添加VC和Mo_(2)C对其组织和力学性能的影响.添加VC和Mo_(2)C均可以抑制WC的溶解-析出过程,从而细化WC晶粒,同时也使黏结相Ni3Al的分布变得均匀,其中VC细化晶粒的效果更明显.添加VC使WC-Ni_(3)Al基硬质合金的相对密度、弯曲强度和断裂韧性降低而硬度提高,当VC含量为0.6%时,WC-Ni_(3)Al基硬质合金的硬度最高为1 413 HV30.当Mo_(2)C含量为1.5%时,WC-Ni_(3)Al基硬质合金的相对密度、弯曲强度和硬度均有所提高但断裂韧性下降,Mo_(2)C含量继续增加时,其相对密度下降且Mo2C会发生偏聚从而降低其力学性能.

关键词： WC-Ni_(3)Al硬质合金碳化物添加剂微波烧结力学性能微观组织

Energy Buildup,Flux Confinement and Helicity Accumulation in the Solar Corona

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Chinese Journal of Astronomy and Astrophysics 2006年第1期6卷 77-86页

作者： You-qiu Hu Wen Li School of Earth and Space Sciences University of Science and Technology of China Hefei230026

Starting from a dipole field ment of field lines on the photosphere, and a given distribution of footpoint displacewe find axisymmetric, force-free field solutions in spherical coordinates that have the same distribution of normal field on the photosphere and magnetic topology as the dipole field. A photospheric shear is introduced in the azimuthal direction in a region that strides across the equator and ends at latitude λs. The footpoint displacement has a sine distribution in latitude and a peak amplitude of φm. The magnetic energy E, azimuthal flux Fφ, and magnetic helicity lit in the solar corona are then calculated for each force-free field solution. It is found that for a given shear region range λs, all of the three quantities increase monotonically with increasing φm. In particular, both Fφ and HT have a linear dependence on φm. When φm reaches a certain critical value φmc, the force-free field loses equilibrium, leading to a partial opening of the field and the appearance of a current sheet in the equatorial plane. At this point, E, Fφ and HT reach their maximum values, Ec, Fφc and HTo Ec increases, and Fφc and HTc decrease with decreasing λs. It is found that Ec is always smaller than the open field energy, in agreement with the Aly conjecture. Of the three critical parameters, Ec has the weakest dependence on λs. Therefore, if one is interested in the transition of a magnetic configuration from a stable state to a dynamic one, the magnetic energy is probably the most appropriate marker of the transition.

关键词： Sun: magnetic fields -- Sun: force-free fields methods: numerical

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“平调五脏”法辨治口罩相关唇炎经验

中华中医药杂志 2024年第2期39卷 822-825页

作者：张曈邱雅琦金连顺唐丽娟张忠德广州中医药大学第二附属医院广州510120 广州中医药大学第二临床医学院广州510450

疫情以来,人们习惯了长时间佩戴口罩,而一部分人长时间佩戴口罩后出现了唇炎,迁延难愈。岭南甄氏杂病流派认为脾胃中枢失衡是引发唇炎的关键,但五脏关系紧扣,都可因别脏而引发唇炎。口罩为邪气提供了滋生的场所,如何平调五脏之阴阳则是... 详细信息

疫情以来,人们习惯了长时间佩戴口罩,而一部分人长时间佩戴口罩后出现了唇炎,迁延难愈。岭南甄氏杂病流派认为脾胃中枢失衡是引发唇炎的关键,但五脏关系紧扣,都可因别脏而引发唇炎。口罩为邪气提供了滋生的场所,如何平调五脏之阴阳则是治疗的重点。岭南甄氏杂病流派第四代代表性传承人张忠德教授提出了“平调五脏”法对其进行辨证论治,文章就张忠德教授以“平调五脏”法辨治口罩相关唇炎的经验进行分享。

关键词：岭南甄氏杂病流派 “平调五脏”法口罩唇炎张忠德经验