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安徽省2021年梅雨期降水预报检验分析 被引量:1
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作者 周胜男 王东勇 +3 位作者 冯颖 柳春 朱珠 刘倪 《沙漠与绿洲气象》 2024年第1期165-173,共9页
对安徽省2021年梅雨期(6月10日—7月10日)6个客观模式和1个主观订正预报产品进行了检验分析,其中包含了3个区域模式数值预报(中国气象局中尺度天气数值预报系统“CMA-MESO”、中国气象局上海数值预报模式系统“CMA-SH9”、安徽WRF,3个... 对安徽省2021年梅雨期(6月10日—7月10日)6个客观模式和1个主观订正预报产品进行了检验分析,其中包含了3个区域模式数值预报(中国气象局中尺度天气数值预报系统“CMA-MESO”、中国气象局上海数值预报模式系统“CMA-SH9”、安徽WRF,3个全球模式数值预报(中国气象局全球同化预报系统“CMA-GFS”、欧洲中期天气预报中心确定性预报模式“ECMWF”、美国国家环境预报中心全球预报系统“NCEP-GFS”)和安徽智能网格主观订正预报的降水产品,结果表明:传统检验中安徽智能网格和区域模式对晴雨准确率的预报效果优于全球模式,又以CMA-MESO最优;在暴雨及以上量级的强降水预报中,传统检验表明安徽智能网格预报的得分最高(23.83),ECMWF模式则是客观模式预报中效果最好的(20.12),CMA-SH9次之(19.34);通过对除安徽智能网格以外的各个客观数值模式进行的MODE空间检验可知,不同数值模式间暴雨预报误差原因不尽相同,ECMWF与各区域数值模式主要是由雨区位置的预报偏差,尤其是纬度偏差导致的,NCEP-GFS全球模式对降水强度和雨区面积的预报偏弱偏小比较明显,CMA-GFS在强降水方面的预报可参考性较差;各个主客观预报暴雨及以上量级预报,整体表现出较明显的日变化特征,在午夜前后、上午时段TS评分较高,而午后到傍晚评分较低,这个现象或许是梅雨期的午后降水多以地表太阳加热引起的短历时热对流降水为主造成的。 展开更多
关键词 降水检验 MODE方法 梅雨 数值预报模式
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“23·7”华北特大暴雨数值预报检验评估 被引量:5
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作者 张博 张芳华 +1 位作者 李晓兰 胡艺 《应用气象学报》 CSCD 北大核心 2024年第1期17-32,共16页
针对“23·7”华北特大暴雨过程,采用天气学检验及TS(thrcat scorc)评分和MODE(mcthod for objcct-bascd diagnostic cvaluation)方法对中国气象局高分辨率全球同化预报系统(CMA-GFS)、较低分辨率全球集合预报系统(CMA-EPS)、欧洲... 针对“23·7”华北特大暴雨过程,采用天气学检验及TS(thrcat scorc)评分和MODE(mcthod for objcct-bascd diagnostic cvaluation)方法对中国气象局高分辨率全球同化预报系统(CMA-GFS)、较低分辨率全球集合预报系统(CMA-EPS)、欧洲中期数值预报中心集合预报系统(EC-EPS)和业务预报模式(EC-HR)、美国环境预报中心全球预报系统(NCEP-GFS)等全球模式和中国气象局区域台风数值预报系统(CMA-TYM)、中尺度天气数值预报系统(CMA-MESO)和区域数值预报系统(CMA-BJ)等进行中短期预报效果检验评估。结果表明:EC-EPS提前14 d预报京津冀一带有过程累积降水量超过100 mm强降水的发生概率,CMA-EPS可提前12 d报出,但预报欠稳定且落区偏东偏南。EC-HR对100 mm以上过程累积降水量及2 d以上暴雨日的位置预报提前时效均达8 d左右,CMA-GFS的过程累积降水量预报显著偏小、强降水落区明显偏东,可用预报时效短;NCEP-GFS预报性能介于二者之间。各模式均可提前36 h预报强降水落区和强度的变化趋势,中尺度模式可更加精细地刻画其形态和位置分布,尤以CMA-BJ为佳,但其预报偏强,其余模式不同程度偏弱,其中CMA-GFS显著偏弱。EC-HR提前8 d预报关键影响系统发生发展,但低层倒槽位置偏西偏北,低空急流偏弱,低估了地形对强降水的增幅作用,是太行山东麓降水量预报偏弱的重要原因之一。整体上,EC-EPS、EC-HR的提前时效和稳定性,以及CMA-BJ的落区形态和强度预报等对预报业务有较高参考价值。 展开更多
关键词 华北特大暴雨 数值模式 天气学检验 TS评分 MODE检验
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基于主客观环流分型的强降水数值预报MODE检验方法及其在2019年暖季东北地区的应用
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作者 齐铎 崔晓鹏 +4 位作者 陈力强 黄丽君 刘松涛 卜文惠 王承伟 《大气科学》 CSCD 北大核心 2024年第3期1113-1130,共18页
本文构建了基于主客观环流分型的强降水数值预报空间检验(MODE)方法框架,并利用该框架对欧洲中期天气预报中心全球模式(ECMWF)和中国气象局区域中尺度数值天气预报模式(CMA_MESO)的2019年暖季东北地区强降水预报进行检验。结果表明,201... 本文构建了基于主客观环流分型的强降水数值预报空间检验(MODE)方法框架,并利用该框架对欧洲中期天气预报中心全球模式(ECMWF)和中国气象局区域中尺度数值天气预报模式(CMA_MESO)的2019年暖季东北地区强降水预报进行检验。结果表明,2019年暖季东北地区54个强降水日的环流型可分为:西风槽型(15个)、副热带高压影响型(13个)、急流型(5个)、西部(12个)和东部冷涡型(9个)。其中,西风槽型和急流型以区域性强降水为主,模式对其强降水发生与否的预报能力强,TS评分较高;西部、东部冷涡型强降水的局地性强,模式对其强降水发生与否的预报能力差,TS评分低;副热带高压影响型也以区域性强降水为主,模式对其强降水发生与否的预报能力也比较强,但是对其强降水质心位置、强度、面积等属性预报偏差较大,TS评分也相对较低。另外,从两种模式预报性能对比看,CMA_MESO强降水强度和面积预报较实况普遍偏强,虽然其预报的TS评分一般高于ECMWF,但其对强降水预报的空报率也都比ECMWF大,对强降水的属性预报偏差一致性一般也低于ECMWF,其预报的可订正性整体上不及ECMWF。 展开更多
关键词 主客观融合环流分型 东北冷涡客观识别 强降水 数值预报 MODE检验
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New direction for surgery:Super minimally invasive surgery 被引量:2
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作者 En-Qiang Linghu 《World Journal of Gastroenterology》 SCIE CAS 2024年第12期1676-1679,共4页
The top goal of modern medicine is treating disease without destroying organ structures and making patients as healthy as they were before their sickness.Minimally invasive surgery(MIS)has dominated the surgical realm... The top goal of modern medicine is treating disease without destroying organ structures and making patients as healthy as they were before their sickness.Minimally invasive surgery(MIS)has dominated the surgical realm because of its lesser invasiveness.However,changes in anatomical structures of the body and reconstruction of internal organs or different organs are common after traditional surgery or MIS,decreasing the quality of life of patients post-operation.Thus,I propose a new treatment mode,super MIS(SMIS),which is defined as“curing a disease or lesion which used to be treated by MIS while preserving the integrity of the organs”.In this study,I describe the origin,definition,operative channels,advantages,and future perspectives of SMIS. 展开更多
关键词 Super minimally invasive surgery Minimally invasive surgery Treatment mode Traditional Surgery New direction for surgery
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2020年北上台风不同模式的预报误差分析 被引量:1
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作者 杨瑞雯 曲荣强 +2 位作者 谭政华 张宸赫 李杨 《成都信息工程大学学报》 2024年第2期208-215,共8页
2020年台风“巴威”、“美莎克”和“海神”直接北上引发了辽宁地区大范围的强降水天气过程。针对业务数值预报模式在路径、强度和降水等方面预报存在一定偏差,利用多家数值模式台风预报资料,采用评分检验和空间检验方法对北上台风的模... 2020年台风“巴威”、“美莎克”和“海神”直接北上引发了辽宁地区大范围的强降水天气过程。针对业务数值预报模式在路径、强度和降水等方面预报存在一定偏差,利用多家数值模式台风预报资料,采用评分检验和空间检验方法对北上台风的模式预报结果进行检验评估,为以后的台风气象预报工作提供参考。结果表明:各模式对台风路径的可预报时效为72 h,随着台风逐渐北上,台风的路径预报误差偏大,台风的强度预报较稳定。在降水的MODE检验结果中,ECMWF全球模式的相似度更高,CMA_MESO_3KM区域模式对降水量级预报偏大,空报较多,但两者对台风降水都有着较好的可参考性,同时台风降水预报效果与台风路径和强度预报密切相关。 展开更多
关键词 台风路径 降水预报 预报检验 空间检验(MODE)
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Dynamic response and failure process of horizontal-layered fractured structure rock slope under strong earthquake 被引量:1
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作者 WANG Tong LIU Xianfeng +5 位作者 HOU Zhaoxu XU Jiahang ZHANG Jun YUAN Shengyang JIANG Guanlu HU Jinshan 《Journal of Mountain Science》 SCIE CSCD 2024年第3期882-900,共19页
Rock slope with horizontal-layered fractured structure(HLFS)has high stability in its natural state.However,a strong earthquake can induce rock fissure expansion,ultimately leading to slope failure.In this study,the d... Rock slope with horizontal-layered fractured structure(HLFS)has high stability in its natural state.However,a strong earthquake can induce rock fissure expansion,ultimately leading to slope failure.In this study,the dynamic response,failure mode,and spectral characteristics of rock slope with HLFS under strong earthquake conditions were investigated based on the large-scale shaking table model test.On this basis,multiple sets of numerical calculation models were further established by UDEC discrete element program.Five influencing factors were considered in the parametric study of numerical simulations,including slope height,slope angle,bedding-plane spacing and secondary joint spacing as well as bedrock dip angle.The results showed that the failure process of rock slope with HLFS under earthquake action is mainly divided into four phases,i.e.,the tensile crack of the slope shoulder joints and shear dislocation at the top bedding plane,the extension of vertical joint cracks and increase of shear displacement,the formation of step-through sliding surfaces and the instability,and finally collapse of fractured rock mass.The acceleration response of slopes exhibits elevation amplification effect and surface effect.Numerical simulations indicate that the seismic stability of slopes with HLFS exhibits a negative correlation with slope height and angle,but a positive correlation with bedding-plane spacing,joint spacing,and bedrock dip angle.The results of this study can provide a reference for seismic stability evaluation of weathered rock slopes. 展开更多
关键词 Seismic behavior Horizontal layered Weathered rock slope Shaking table test Failure mode
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Investigation of hydroxyl-terminated polybutadiene propellant breaking characteristics and mechanism impacted by submerged cavitation water jet 被引量:1
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作者 Wenjun Zhou Meng Zhao +3 位作者 Bo Liu Youzhi Ma Youzhi Zhang Xuanjun Wang 《Defence Technology(防务技术)》 SCIE EI CAS CSCD 2024年第3期559-572,共14页
A submerged cavitation water jet(SCWJ)is an effective method to recycle solid propellant from obsolete solid engines by the breaking method.Solid propellant's breaking modes and mechanical process under SCWJ impac... A submerged cavitation water jet(SCWJ)is an effective method to recycle solid propellant from obsolete solid engines by the breaking method.Solid propellant's breaking modes and mechanical process under SCWJ impact are unclear.This study aims to understand those impact breaking mechanisms.The hydroxyl-terminated polybutadiene(HTPB)propellant was chosen as the research material,and a self-designed test system was used to conduct impact tests at four different working pressures.The high-speed camera characterized crack propagation,and the DIC method calculated strain change during the impact process.Besides,micro and macro fracture morphologies were characterized by scanning electron microscope(SEM)and computed tomography(CT)scanning.The results reveal that the compressive strain concentration region locates right below the nozzle,and the shear strain region distributes symmetrically with the jet axis,which increases to 4% at first 16th ms,the compressive strain rises to 2% and 6% in the axial and transverse direction,respectively.The two tensile cracks formed first at the compression strain concentrate region,and there generate many shear cracks around the tensile cracks,and those shear cracks that develop and aggregate cause the cracks to become wider and cut through the tensile cracks,forming the tensile-shear cracks and the impact parts eventually fail.The HTPB propellant forms a breaking hole shaped conical after impact 10 s.The mass loss increases by 17 times at maximum,with the working pressure increasing by three times.Meanwhile,the damage value of the breaking hole remaining on the surface increases by 7.8 times while 2.9 times in the depth of the breaking hole.The breaking efficiency is closely affected by working pressures.The failure modes of HTPB impacted by SCWJ are classified as tensile crack-dominated and tensile-shear crack-dominated damage mechanisms. 展开更多
关键词 Submerged cavitation water jet Hydroxyl-terminated polybutadiene propellant Breaking characteristics Failure modes
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Prediction of subsurface settlement induced by shield tunnelling in sandy cobble stratum 被引量:1
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作者 Fan Wang Xiuli Du Pengfei Li 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2024年第1期192-212,共21页
This study focuses on the analytical prediction of subsurface settlement induced by shield tunnelling in sandy cobble stratum considering the volumetric deformation modes of the soil above the tunnel crown.A series of... This study focuses on the analytical prediction of subsurface settlement induced by shield tunnelling in sandy cobble stratum considering the volumetric deformation modes of the soil above the tunnel crown.A series of numerical analyses is performed to examine the effects of cover depth ratio(C/D),tunnel volume loss rate(h t)and volumetric block proportion(VBP)on the characteristics of subsurface settle-ment trough and soil volume loss.Considering the ground loss variation with depth,three modes are deduced from the volumetric deformation responses of the soil above the tunnel crown.Then,analytical solutions to predict subsurface settlement for each mode are presented using stochastic medium theory.The influences of C/D,h t and VBP on the key parameters(i.e.B and N)in the analytical expressions are discussed to determine the fitting formulae of B and N.Finally,the proposed analytical solutions are validated by the comparisons with the results of model test and numerical simulation.Results show that the fitting formulae provide a convenient and reliable way to evaluate the key parameters.Besides,the analytical solutions are reasonable and available in predicting the subsurface settlement induced by shield tunnelling in sandy cobble stratum. 展开更多
关键词 Shield tunnelling Sandy cobble stratum Subsurface settlement Volumetric deformation mode Stochastic medium theory
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UAV-assisted data collection for wireless sensor networks with dynamic working modes 被引量:1
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作者 Jie Chen Jianhua Tang 《Digital Communications and Networks》 SCIE CSCD 2024年第3期805-812,共8页
Wireless Sensor Network(WSN)is a cornerstone of Internet of Things(IoT)and has rich application scenarios.In this work,we consider a heterogeneous WSN whose sensor nodes have a diversity in their Residual Energy(RE).I... Wireless Sensor Network(WSN)is a cornerstone of Internet of Things(IoT)and has rich application scenarios.In this work,we consider a heterogeneous WSN whose sensor nodes have a diversity in their Residual Energy(RE).In this work,to protect the sensor nodes with low RE,we investigate dynamic working modes for sensor nodes which are determined by their RE and an introduced energy threshold.Besides,we employ an Unmanned Aerial Vehicle(UAV)to collect the stored data from the heterogeneous WSN.We aim to jointly optimize the cluster head selection,energy threshold and sensor nodes’working mode to minimize the weighted sum of energy con-sumption from the WSN and UAV,subject to the data collection rate constraint.To this end,we propose an efficient search method to search for an optimal energy threshold,and develop a penalty-based successive convex approximation algorithm to select the cluster heads.Then we present a low-complexity iterative approach to solve the joint optimization problem and discuss the implementation procedure.Numerical results justify that our proposed approach is able to reduce the energy consumption of the sensor nodes with low RE significantly and also saves energy for the whole WSN. 展开更多
关键词 Unmanned aerial vehicle Wireless sensor networks Cluster heads Dynamic working modes
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Adaptive Trajectory Tracking Control for Nonholonomic Wheeled Mobile Robots:A Barrier Function Sliding Mode Approach 被引量:1
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作者 Yunjun Zheng Jinchuan Zheng +3 位作者 Ke Shao Han Zhao Hao Xie Hai Wang 《IEEE/CAA Journal of Automatica Sinica》 SCIE EI CSCD 2024年第4期1007-1021,共15页
The trajectory tracking control performance of nonholonomic wheeled mobile robots(NWMRs)is subject to nonholonomic constraints,system uncertainties,and external disturbances.This paper proposes a barrier function-base... The trajectory tracking control performance of nonholonomic wheeled mobile robots(NWMRs)is subject to nonholonomic constraints,system uncertainties,and external disturbances.This paper proposes a barrier function-based adaptive sliding mode control(BFASMC)method to provide high-precision,fast-response performance and robustness for NWMRs.Compared with the conventional adaptive sliding mode control,the proposed control strategy can guarantee that the sliding mode variables converge to a predefined neighborhood of origin with a predefined reaching time independent of the prior knowledge of the uncertainties and disturbances bounds.Another advantage of the proposed algorithm is that the control gains can be adaptively adjusted to follow the disturbances amplitudes thanks to the barrier function.The benefit is that the overestimation of control gain can be eliminated,resulting in chattering reduction.Moreover,a modified barrier function-like control gain is employed to prevent the input saturation problem due to the physical limit of the actuator.The stability analysis and comparative experiments demonstrate that the proposed BFASMC can ensure the prespecified convergence performance of the NWMR system output variables and strong robustness against uncertainties/disturbances. 展开更多
关键词 Adaptive sliding mode barrier function nonholonomic wheeled mobile robot(NWMR) trajectory tracking control
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Observer-based robust high-order fully actuated attitude autopilot design for spinning glide-guided projectiles 被引量:1
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作者 Wei Wang Yuchen Wang +2 位作者 Shiwei Chen Yongcang Guo Zhongjiao Shi 《Defence Technology(防务技术)》 SCIE EI CAS CSCD 2024年第4期282-294,共13页
This paper investigates the design of an attitude autopilot for a dual-channel controlled spinning glideguided projectile(SGGP),addressing model uncertainties and external disturbances.Based on fixed-time stable theor... This paper investigates the design of an attitude autopilot for a dual-channel controlled spinning glideguided projectile(SGGP),addressing model uncertainties and external disturbances.Based on fixed-time stable theory,a disturbance observer with integral sliding mode and adaptive techniques is proposed to mitigate total disturbance effects,irrespective of initial conditions.By introducing an error integral signal,the dynamics of the SGGP are transformed into two separate second-order fully actuated systems.Subsequently,employing the high-order fully actuated approach and a parametric approach,the nonlinear dynamics of the SGGP are recast into a constant linear closed-loop system,ensuring that the projectile's attitude asymptotically tracks the given goal with the desired eigenstructure.Under the proposed composite control framework,the ultimately uniformly bounded stability of the closed-loop system is rigorously demonstrated via the Lyapunov method.Validation of the effectiveness of the proposed attitude autopilot design is provided through extensive numerical simulations. 展开更多
关键词 Spinning glide-guided projectile Attitude control Sliding mode disturbance observer Fixed-time stable theory High-order fully actuated approach
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Resonantly enhanced second-and third-harmonic generation in dielectric nonlinear metasurfaces 被引量:1
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作者 Ji Tong Wang Pavel Tonkaev +5 位作者 Kirill Koshelev Fangxing Lai Sergey Kruk Qinghai Song Yuri Kivshar Nicolae C.Panoiu 《Opto-Electronic Advances》 SCIE EI CAS CSCD 2024年第5期5-19,共15页
Nonlinear dielectric metasurfaces provide a promising approach to control and manipulate frequency conversion optical processes at the nanoscale,thus facilitating both advances in fundamental research and the developm... Nonlinear dielectric metasurfaces provide a promising approach to control and manipulate frequency conversion optical processes at the nanoscale,thus facilitating both advances in fundamental research and the development of new practical applications in photonics,lasing,and sensing.Here,we employ symmetry-broken metasurfaces made of centrosymmetric amorphous silicon for resonantly enhanced second-and third-order nonlinear optical response.Exploiting the rich physics of optical quasi-bound states in the continuum and guided mode resonances,we comprehensively study through rigorous numerical calculations the relative contribution of surface and bulk effects to second-harmonic generation(SHG)and the bulk contribution to third-harmonic generation(THG) from the meta-atoms.Next,we experimentally achieve optical resonances with high quality factors,which greatly boosts light-matter interaction,resulting in about 550 times SHG enhancement and nearly 5000-fold increase of THG.A good agreement between theoretical predictions and experimental measurements is observed.To gain deeper insights into the physics of the investigated nonlinear optical processes,we further numerically study the relation between nonlinear emission and the structural asymmetry of the metasurface and reveal that the generated harmonic signals arising from linear sharp resonances are highly dependent on the asymmetry of the meta-atoms.Our work suggests a fruitful strategy to enhance the harmonic generation and effectively control different orders of harmonics in all-dielectric metasurfaces,enabling the development of efficient active photonic nanodevices. 展开更多
关键词 second-harmonic generation third-harmonic generation bound state in the continuum guided mode resonance all-dielectric metasurfaces nonlinear optics
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Trajectory tracking guidance of interceptor via prescribed performance integral sliding mode with neural network disturbance observer 被引量:1
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作者 Wenxue Chen Yudong Hu +1 位作者 Changsheng Gao Ruoming An 《Defence Technology(防务技术)》 SCIE EI CAS CSCD 2024年第2期412-429,共18页
This paper investigates interception missiles’trajectory tracking guidance problem under wind field and external disturbances in the boost phase.Indeed,the velocity control in such trajectory tracking guidance system... This paper investigates interception missiles’trajectory tracking guidance problem under wind field and external disturbances in the boost phase.Indeed,the velocity control in such trajectory tracking guidance systems of missiles is challenging.As our contribution,the velocity control channel is designed to deal with the intractable velocity problem and improve tracking accuracy.The global prescribed performance function,which guarantees the tracking error within the set range and the global convergence of the tracking guidance system,is first proposed based on the traditional PPF.Then,a tracking guidance strategy is derived using the integral sliding mode control techniques to make the sliding manifold and tracking errors converge to zero and avoid singularities.Meanwhile,an improved switching control law is introduced into the designed tracking guidance algorithm to deal with the chattering problem.A back propagation neural network(BPNN)extended state observer(BPNNESO)is employed in the inner loop to identify disturbances.The obtained results indicate that the proposed tracking guidance approach achieves the trajectory tracking guidance objective without and with disturbances and outperforms the existing tracking guidance schemes with the lowest tracking errors,convergence times,and overshoots. 展开更多
关键词 BP network neural Integral sliding mode control(ISMC) Missile defense Prescribed performance function(PPF) State observer Tracking guidance system
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Control method based on DRFNN sliding mode for multifunctional flexible multistate switch 被引量:1
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作者 Jianghua Liao Wei Gao +1 位作者 Yan Yang Gengjie Yang 《Global Energy Interconnection》 EI CSCD 2024年第2期190-205,共16页
To address the low accuracy and stability when applying classical control theory in distribution networks with distributed generation,a control method involving flexible multistate switches(FMSs)is proposed in this st... To address the low accuracy and stability when applying classical control theory in distribution networks with distributed generation,a control method involving flexible multistate switches(FMSs)is proposed in this study.This approach is based on an improved double-loop recursive fuzzy neural network(DRFNN)sliding mode,which is intended to stably achieve multiterminal power interaction and adaptive arc suppression for single-phase ground faults.First,an improved DRFNN sliding mode control(SMC)method is proposed to overcome the chattering and transient overshoot inherent in the classical SMC and reduce the reliance on a precise mathematical model of the control system.To improve the robustness of the system,an adaptive parameter-adjustment strategy for the DRFNN is designed,where its dynamic mapping capabilities are leveraged to improve the transient compensation control.Additionally,a quasi-continuous second-order sliding mode controller with a calculus-driven sliding mode surface is developed to improve the current monitoring accuracy and enhance the system stability.The stability of the proposed method and the convergence of the network parameters are verified using the Lyapunov theorem.A simulation model of the three-port FMS with its control system is constructed in MATLAB/Simulink.The simulation result confirms the feasibility and effectiveness of the proposed control strategy based on a comparative analysis. 展开更多
关键词 Distribution networks Flexible multistate switch Grounding fault arc suppression Double-loop recursive fuzzy neural network Quasi-continuous second-order sliding mode
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High-speed performance self-powered short wave ultraviolet radiation detectors based onκ(ε)-Ga_(2)O_(3) 被引量:1
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作者 Aleksei Almaev Alexander Tsymbalov +5 位作者 Bogdan Kushnarev Vladimir Nikolaev Alexei Pechnikov Mikhail Scheglov Andrei Chikiryaka Petr Korusenko 《Journal of Semiconductors》 EI CAS CSCD 2024年第4期56-62,共7页
High-speed solar-blind short wavelength ultraviolet radiation detectors based onκ(ε)-Ga_(2)O_(3)layers with Pt contacts were demonstrated and their properties were studied in detail.Theκ(ε)-Ga_(2)O_(3)layers were ... High-speed solar-blind short wavelength ultraviolet radiation detectors based onκ(ε)-Ga_(2)O_(3)layers with Pt contacts were demonstrated and their properties were studied in detail.Theκ(ε)-Ga_(2)O_(3)layers were deposited by the halide vapor phase epitaxy on patterned GaN templates with sapphire substrates.The spectral dependencies of the photoelectric properties of struc-tures were analyzed in the wavelength interval 200-370 nm.The maximum photo to dark current ratio,responsivity,detectiv-ity and external quantum efficiency of structures were determined as:180.86 arb.un.,3.57 A/W,1.78×10^(12) Hz^(0.5)∙cm·W^(-1) and 2193.6%,respectively,at a wavelength of 200 nm and an applied voltage of 1 V.The enhancement of the photoresponse was caused by the decrease in the Schottky barrier at the Pt/κ(ε)-Ga_(2)O_(3)interface under ultraviolet exposure.The detectors demon-strated could functionalize in self-powered mode due to built-in electric field at the Pt/κ(ε)-Ga_(2)O_(3)interface.The responsivity and external quantum efficiency of the structures at a wavelength of 254 nm and zero applied voltage were 0.9 mA/W and 0.46%,respectively.The rise and decay times in self-powered mode did not exceed 100 ms. 展开更多
关键词 κ(ε)-gallium oxide solar-blind shortwave ultraviolet radiation detectors self-powered operation mode
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Analysis of factors impacting postoperative pain and quality of life in patients with mixed hemorrhoids:A retrospective study 被引量:1
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作者 Xiao-Wen Sun Jing-Yi Xu +3 位作者 Chang-Zhen Zhu Si-Jia Li Lu-Jia Jin Zhi-Dong Zhu 《World Journal of Gastrointestinal Surgery》 SCIE 2024年第3期731-739,共9页
BACKGROUND Hemorrhoids are among the most common and frequently encountered chronic anorectal diseases in anorectal surgery.They are venous clusters formed by con-gestion,expansion,and flexion of the venous plexus in ... BACKGROUND Hemorrhoids are among the most common and frequently encountered chronic anorectal diseases in anorectal surgery.They are venous clusters formed by con-gestion,expansion,and flexion of the venous plexus in the lower part of the rec-tum.Mixed hemorrhoids bleed easily and recurrently,and this can result in severe anemia.Hence,they may have a negative effect on the health of the patient and surgical treatment is required.Milligan-Morgan hemorrhoidectomy has been widely used since 1937 for the treatment of grade III and IV hemorrhoids.How-ever,most patients experience different degrees of postoperative pain that may cause anxiety.with mixed hemorrhoids post-surgery.METHODS The clinical data of patients with mixed hemorrhoids who underwent Milligan-Morgan hemorrhoidectomy were collected retrospectively.The basic character-istics of the enrolled patients with mixed hemorrhoids were recorded,and based on the Goligher clinical grading system,the hemorrhoids were classified as grades III or IV.The endpoint of this study was the disappearance of pain in all patients.Quantitative data were presented as mean±SD,such as age,pain score,and QoL score.Student’s t-test was used to compare the groups.RESULTS A total of 164 patients were enrolled.The distribution of the visual analog scale pain scores of all patients at 3,7,14 and 28 d after surgery showed that post-surgery pain was significantly reduced with the passage of time.Fourteen days after the operation,the pain had completely disappeared in some patients.Twenty-eight days after the surgery,none of the patients experienced any pain.Comparing the World Health Or-ganization Quality of Life-BREF self-reporting questionnaire scores of patients between 14 and 28 d after surgery,we observed that the quality-of-life scores of the patients post-surgery had significantly improved.There were six items that were compared at 14-and 28-d post-surgery.The mean QoL score 28 d after surgery(4.79±0.46)was higher than that at 14 d post-surgery(3.79±0.57).The mean health condition score 28 d after surgery(4.80±0.41)was also higher than that at 14 d post-surgery(4.01±0.62).The mean physical health score 28 d after surgery(32.10±2.96)was significantly higher than that at 14 d post-surgery(23.41±2.85).The mean psychological health score 28 d after surgery(27.22±1.62)was significantly higher than that at 14 d post-surgery(21.37±1.70).The mean social relations score 28 d after surgery(12.21±1.59)was significantly higher than that at 14 d post-surgery(6.32±1.66).The mean surrounding environment score 28 d after surgery(37.13±2.88)was significantly higher than that at 14 d post-surgery(28.42±2.86).The differences in quality-of-life scores at day 14 and day 28 post-surgery were ob-served to be statistically significant(P<0.001).CONCLUSION Milligan-Morgan hemorrhoidectomy can significantly improve the postoperative QoL of patients.Age,sex,and the number of surgical resections were important factors influencing Milligan-Morgan hemorrhoidectomy. 展开更多
关键词 HEMORRHOIDS Mixed hemorrhoids Milligan organ hemorrhoidectomy Postoperative pain Quality of life Anesthesia mode
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基于CEEMDAN-HT的永磁同步电机匝间短路振动信号故障特征提取研究 被引量:2
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作者 夏焰坤 李欣洋 +1 位作者 任俊杰 寇坚强 《振动与冲击》 EI CSCD 北大核心 2024年第5期72-81,共10页
由于长时间处于高负荷运行状态,永磁同步电机(permanent magnet synchronous motor, PMSM)定子绕组线圈匝与匝之间的绝缘性能容易降低,导致出现匝间短路,此时电机的振动强度会发生改变。针对此现象,提出将自适应噪声完备经验模态分解(co... 由于长时间处于高负荷运行状态,永磁同步电机(permanent magnet synchronous motor, PMSM)定子绕组线圈匝与匝之间的绝缘性能容易降低,导致出现匝间短路,此时电机的振动强度会发生改变。针对此现象,提出将自适应噪声完备经验模态分解(complete ensemble empirical mode decomposition with adaptive noise, CEEMDAN)与希尔伯特变换(Hilbert transform, HT)结合,构成一种CEEMDAN-HT非线性信号分析方法,并将其应用于提取振动信号故障特征。首先,利用CEEMDAN算法分解振动信号,得到一系列本征模态函数(intrinsic mode function, IMF),并将主元分析中的方差贡献率用于识别包含故障特征信息的IMF。其次,使用HT对方差贡献率较高的IMF进行分析,并以三维联合时频图呈现时间、瞬时频率与幅值,得到了主要故障特征。最后,使用ANSYS有限元软件建立了电机短路故障模型,并搭建了短路故障试验平台,通过对比有限元仿真结果与试验结果,对提出的方法进行了有效性和准确性验证。 展开更多
关键词 永磁同步电机(permanent magnet synchronous motor PMSM) 振动信号 自适应噪声完备经验模态分解(complete ensemble empirical mode decomposition with adaptive noise CEEMDAN) 特征提取 希尔伯特变换(Hilbert transform HT)
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Real-Time 4-Mode MDM Transmission Using Commercial 400G OTN Transceivers and All-Fiber Mode Multiplexers 被引量:1
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作者 REN Fang LI Yidan +2 位作者 YE Bing LIU Jianguo CHEN Weizhang 《ZTE Communications》 2024年第1期106-110,共5页
Weakly-coupled mode division multiplexing(MDM)technique is considered a promising candidate to enhance the capacity of an optical transmission system,in which mode multiplexers/demultiplexers(MMUX/MDEMUX)with low inse... Weakly-coupled mode division multiplexing(MDM)technique is considered a promising candidate to enhance the capacity of an optical transmission system,in which mode multiplexers/demultiplexers(MMUX/MDEMUX)with low insertion loss and modal crosstalk are the key components.In this paper,a low-modal-crosstalk 4-mode MMUX/MDEMUX for the weakly-coupled triple-ring-core few-mode fiber(TRC-FMF)is designed and fabricated with side-polishing processing.The measurement results show that a pair of MMUX/MDEMUX and 25 km weakly-coupled TRC-FMF MDM link achieve low modal crosstalk of lower than−17.5 dB and insertion loss of lower than 11.56 dB for all the four modes.Based on the TRC-FMF and all-fiber MMUX/MDEMUX,an experiment for 25 km real-time 4-mode 3-λwavelength division multiplexing(WDM)-MDM transmission is conducted using commercial 400G optical transport network(OTN)transceivers.The experimental results prove weakly-coupled MDM techniques facilitate a smooth upgrade of the optical transmission system. 展开更多
关键词 optical fiber couplers mode(de)multiplexers mode division multiplexing transmission
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Transition from a filamentary mode to a diffuse one with varying distance from needle to stream of an argon plasma jet
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作者 许慧敏 高敬格 +3 位作者 贾鹏英 冉俊霞 陈俊宇 李金懋 《Chinese Physics B》 SCIE EI CAS CSCD 2024年第1期539-544,共6页
Plasma jet has extensive application potentials in various fields, which normally operates in a diffuse mode when helium is used as the working gas. However, when less expensive argon is used, the plasma jet often ope... Plasma jet has extensive application potentials in various fields, which normally operates in a diffuse mode when helium is used as the working gas. However, when less expensive argon is used, the plasma jet often operates in a filamentary mode. Compared to the filamentary mode, the diffuse mode is more desirable for applications. Hence, many efforts have been exerted to accomplish the diffuse mode of the argon plasma jet. In this paper, a novel single-needle argon plasma jet is developed to obtain the diffuse mode. It is found that the plasma jet operates in the filamentary mode when the distance from the needle tip to the central line of the argon stream(d) is short. It transits to the diffuse mode with increasing d. For the diffuse mode, there is always one discharge pulse per voltage cycle, which initiates at the rising edge of the positive voltage. For comparison, the number of discharge pulse increases with an increase in the peak voltage for the filamentary mode. Fast photography reveals that the plasma plume in the filamentary mode results from a guided positive streamer,which propagates in the argon stream. However, the plume in the diffuse mode originates from a branched streamer, which propagates in the interfacial layer between the argon stream and the surrounding air. By optical emission spectroscopy,plasma parameters are investigated for the two discharge modes, which show a similar trend with increasing d. The diffuse mode has lower electron temperature, electron density, vibrational temperature, and gas temperature compared to the filamentary mode. 展开更多
关键词 plasma jet diffuse mode filamentary mode optical emission spectroscopy
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Investigation on the roles of equilibrium toroidal rotation during edge-localized mode mitigated by resonant magnetic perturbations
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作者 董良康 陈少永 +3 位作者 牟茂淋 罗杨 秦晨晨 唐昌建 《Plasma Science and Technology》 SCIE EI CAS CSCD 2024年第1期16-33,共18页
The effects of equilibrium toroidal rotation during edge-localized mode(ELM)mitigated by resonant magnetic perturbation(RMP)are studied with the experimental equilibria of the EAST tokamak based on the four-field mode... The effects of equilibrium toroidal rotation during edge-localized mode(ELM)mitigated by resonant magnetic perturbation(RMP)are studied with the experimental equilibria of the EAST tokamak based on the four-field model in the BOUT++code.As the two main parameters to determine the toroidal rotation profiles,the rotation shear and magnitudes were separately scanned to investigate their roles in the impact of RMPs on peeling-ballooning(P-B)modes.On one hand,the results show that strong toroidal rotation shear is favorable for the enhancement of the self-generated E×B shearing rate<ω_(E×B)>with RMPs,leading to significant ELM mitigation with RMP in the stronger toroidal rotation shear region.On the other hand,toroidal rotation magnitudes may affect ELM mitigation by changing the penetration of the RMPs,more precisely the resonant components.RMPs can lead to a reduction in the pedestal energy loss by enhancing the multimode coupling in the turbulence transport phase.The shielding effects on RMPs increase with the toroidal rotation magnitude,leading to the enhancement of the multimode coupling with RMPs to be significantly weakened.Hence,the reduction in pedestal energy loss by RMPs decreased with the rotation magnitude.In brief,the results show that toroidal rotation plays a dual role in ELM mitigation with RMP by changing the shielding effects of plasma by rotation magnitude and affecting<ω_(E×B)>by rotation shear.In the high toroidal rotation region,toroidal rotation shear is usually strong and hence plays a dominant role in the influence of RMP on P-B modes,whereas in the low rotation region,toroidal rotation shear is weak and has negligible impact on P-B modes,and the rotation magnitude plays a dominant role in the influence of RMPs on the P-B modes by changing the field penetration.Therefore,the dual role of toroidal rotation leads to stronger ELM mitigation with RMP,which may be achieved both in the low toroidal rotation region and the relatively high rotation region that has strong rotational shear. 展开更多
关键词 edge-localized mode peeling–ballooning modes resonant magnetic perturbation toroidal rotation plasma response TOKAMAK
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