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飞机设计 2018年第4期38卷 47-51页

作者：胡光郑植天李永恒海军航空大学航空基础学院山东烟台264001 国网河北省电力有限公司灵寿县供电分公司河北石家庄050500

为增强航空电源系统的可靠性,以九开关变换器驱动的双Y移30°永磁同步电机为研究对象,研究了相应的容错控制方法。针对九开关变换器单个开关管的短路故障,首先介绍了九开关变换器的工作原理及基于有效作用时间的载波调制PWM方法的基本原... 详细信息

为增强航空电源系统的可靠性,以九开关变换器驱动的双Y移30°永磁同步电机为研究对象,研究了相应的容错控制方法。针对九开关变换器单个开关管的短路故障,首先介绍了九开关变换器的工作原理及基于有效作用时间的载波调制PWM方法的基本原理,当变换器发生开关管短路情况时,展开容错控制,最后在Matlab/Simulink中进行了仿真试验,得到容错控制后的试验图形。试验结果验证了所提出算法的正确性,提高了电机的可靠性。

关键词：九开关变换器载波调制PWM控制开关管短路六相PMSM 容错控制

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紫荆皮镇痛抗炎活性部位的筛选

药品评价 2023年第4期20卷 402-407页

作者：李正红郑志田梁生林南昌大学第四附属医院江西南昌330003 井冈山大学医学部江西吉安343009

目的对紫荆皮的镇痛抗炎活性部位进行筛选。方法利用热板法、乙酸扭体法的疼痛模型,研究紫荆皮产生止痛效果的活性部位;利用二甲苯致小鼠耳廓肿胀、蛋清致大鼠脚跖肿胀和棉球致大鼠肉芽肿的急慢性炎症模型,探究紫荆皮发挥抗炎作用的活... 详细信息

目的对紫荆皮的镇痛抗炎活性部位进行筛选。方法利用热板法、乙酸扭体法的疼痛模型,研究紫荆皮产生止痛效果的活性部位;利用二甲苯致小鼠耳廓肿胀、蛋清致大鼠脚跖肿胀和棉球致大鼠肉芽肿的急慢性炎症模型,探究紫荆皮发挥抗炎作用的活性部位。结果紫荆皮的醋酸乙酯萃取部位,对通电热板所产生的痛阈与自身给药前和正常对照组比较明显延长(P<0.01);对乙酸刺激所引起的小鼠扭体反应发生率与正常对照组比较明显下降(P<0.01);对均匀涂布二甲苯所引起的小鼠耳廓肿胀,脚跖皮下注射蛋清所引起的大鼠脚跖肿胀,以及埋棉球所引起的大鼠肉芽肿与正常对照组比较抑制明显,差异有统计学意义(P<0.01)。结论紫荆皮的镇痛抗炎活性部位主要为醋酸乙酯萃取部位。

关键词：紫荆皮镇痛抗炎活性部位黄酮类

基于台区负荷矩的农村配电线路电压质量评估方法

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广西电力 2019年第6期42卷 22-25页

作者：刘柏江郑智天蒙理平唐忠康广西宏湖水利电业科技发展有限公司

随着分布式电源的大量接入,农村配电网的电压问题更加突出。为了改善农村配电网的电压质量,提出一种基于台区负荷矩的电压质量评估方法,并通过算例验证了该方法的有效性。算例结果表明,该方法可以直观地反映了电压质量的动态变化过程,... 详细信息

随着分布式电源的大量接入,农村配电网的电压问题更加突出。为了改善农村配电网的电压质量,提出一种基于台区负荷矩的电压质量评估方法,并通过算例验证了该方法的有效性。算例结果表明,该方法可以直观地反映了电压质量的动态变化过程,并且能准确判断供电区域有功/无功薄弱节点。评估结果为农村配电网电压质量治理和配电网改造提供了决策依据。

关键词：农村配电网台区负荷矩电压质量电压波动

Mean wind load induced incompatibility in nonlinear aeroelastic simulations of bridge spans

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Frontiers of Structural and Civil Engineering 2019年第3期13卷 605-617页

作者： zhitian ZHANG Wind Engineering Research Center Hunan UniversityChangsha 410082China

Mean wind response induced incompatibility and nonlinearity in bridge aerodynamics is discussed,where the mean wind and aeroelastic loads are applied simultaneously in time domain.A kind of incompatibility is found during the simultaneous simulation of the mean wind and aeroelastic loads,which leads to incorrect mean wind structural *** is found that the mathematic expectations (or Iimiting characteristics) of the aeroelastic models are fundamental to this kind of *** this paper,two aeroelastic models are presented and discussed,one of indicial-function-denoted (IF-denoted) and another of rational-function-denoted (RF-denoted).It is shown that,in cases of low wind speeds,the IF-denoted model reflects correctly the mean wind load properties,and results in correct mean structural responses;in contrast,the RF-denoted model leads to incorrect mean responses due to its nonphysical mean *** very high wind speeds,however,even the IF-denoted model can lead to significant deviation from the correct response due to steady aerodynamic *** solve the incompatibility at high wind speeds,a methodology of subtraction of pseudo-steady effects from the aeroelastic model is put forward in this ***,with the method presented,aeroelastic nonlinearity resulted from the mean wind response is investigated at both moderate and high wind speeds.

关键词： bridge aerodynamics nonlinear aeroelastic model Pseudo-steady mean wind loads

Novel nondelay-based reservoir computing with a single micromechanical nonlinear resonator for high-efficiency information processing

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Microsystems & Nanoengineering 2021年第5期7卷 71-81页

作者： Jie Sun Wuhao Yang Tianyi zheng Xingyin Xiong Yunfei Liu zheng Wang zhitian Li Xudong Zouu The State Key Laboratory of Transducer Technology Aerospace Information Research InstituteChinese Academy of SciencesBeijingChina School of Electronic Electrical and Communication EngineeringUniversity of Chinese Academy of SciencesBeijingChina QILU Aerospace Information Research Institute JinanChina

Reservoir computing is a potential neuromorphic paradigm for promoting future disruptive applications in the era of the Internet of Things,owing to its well-known low training cost and compatibility with *** has been successfully implemented by injecting an input signal into a spatially extended reservoir of nonlinear nodes or a temporally extended reservoir of a delayed feedback system to perform temporal information *** we propose a novel nondelay-based reservoir computer using only a single micromechanical resonator with hybrid nonlinear dynamics that removes the usually required delayed feedback *** hybrid nonlinear dynamics of the resonator comprise a transient nonlinear response,and a Duffing nonlinear response is first used for reservoir *** to the richness of this nonlinearity,the usually required delayed feedback loop can be *** further simplify and improve the efficiency of reservoir computing,a self-masking process is utilized in our novel reservoir ***,we numerically and experimentally demonstrate its excellent performance,and our system achieves a high recognition accuracy of 93%on a handwritten digit recognition benchmark and a normalized mean square error of 0.051 in a nonlinear autoregressive moving average task,which reveals its memory ***,it also achieves 97.17±1%accuracy on an actual human motion gesture classification task constructed from a six-axis IMU *** remarkable results verify the feasibility of our system and open up a new pathway for the hardware implementation of reservoir computing.

关键词： nonlinear delay remove

METALLOGENIC EVOLUTION AND MODEL OF MANZHOULI-XINBAERHU METALLOGENIC PROVINCE

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Transactions of Nonferrous Metals Society of China 1992年第2期2卷 8-15页

作者： Wang zhitian Pan Longju Beijing Institute of Geology for Mineral Resources Beijing 100012China No.706 Party.Nonferrous Metals Geological Exploration Bureau of Heilongjing Province

This area is a superlarge potentiality metallogenic province of multimetal resource,belonging to Ergun accretionary fold system of early *** regional basement(Neoproterozoic-Lower Cambrian Series)is the outer extent of the Siberian craton margin,and the metallization in this area was affected intensely by Pacific plate *** NE trending Ergun-Hulun deep-seated fracture controls the giant volcano-magmatic activty and mineralization in this *** cross trending tenso-shear fractures control the formation of ore cluster in this *** major types of ore deposits in this area are porphyry type,subvolcanic hydrothermal vein type and skarn *** are the products of different depths and environments as genetically-related,which can be collectively regarded as porphyry copper-multimetal metallogenic series.

关键词： Manzhouli metallogenic province metallogenic evolution metallogenic model porphyry

A decouple-decomposition noise analysis model for closed-loop mode-localized tilt sensors

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Microsystems & Nanoengineering 2023年第6期9卷 297-307页

作者： Kunfeng Wang XingYin Xiong zheng Wang Liangbo Ma BoWen Wang WuHao Yang Xiaorui Bie zhitian Li XuDong Zou The State Key Laboratory of Transducer Technology Aerospace Information Research InstituteChinese Academy of SciencesBeijingChina School of Electronic Electrical and Communication EngineeringUniversity of Chinese Academy of SciencesBeijingChina Ming Hsieh Department of Electrical and Computer Engineering University of Southern CaliforniaLos AngelesCAUSA Shangdong Key Laboratory of Low-altitude Airspace Surveillance Network Technology QiLu Aerospace Information Research InstituteJinanChina

The development of mode-localized sensors based on amplitude output metrics has attracted increasing attention in recent years due to the potential of such sensors for high sensitivity and ***-localization phenomena leverage the interaction between multiple coupled resonant modes to achieve enhanced performance,providing a promising solution to overcome the limitations of traditional sensing *** noise plays a key role in determining the resolution of mode-localized sensors,as the output metric is derived from the measured AR(amplitude ratio)within the weakly coupled resonator ***,the amplitude noise originating from the weakly coupled resonator's closed-loop circuit has not yet been fully *** paper presents a decouple-decomposition(DD)noise analysis model,which is applied to achieve high resolution in a mode-localized tilt sensor based on a weakly coupled resonator closed-loop *** DD noise model separates the weakly coupled resonators using the decoupling method considering the nonlinearity of the *** integrating the decoupled weakly coupled resonators,the model decomposes the weakly coupled resonator's closed-loop circuit into distinct paths for amplitude and phase noise *** DD noise model reveals noise effects at various circuit nodes and models the system noise in the closed-loop circuit of the weakly coupled ***/Simulink simulations verify the model's accuracy when compared to theoretical *** the optimal operating point,the mode-localized tilt sensor achieves an input-referred instability of 3.91×10^(-4°)and an input-referred AR of PSD of 2.01×10^(-4°)⁄√Hz using the closed-loop noise *** model is also applicable to other varieties of mode-localized sensors.

关键词： weakly couple overcome

Bearing capacity and failure behavior of disconnectable coupling joint with double row wedges(DCJD)used in the prestressed internal bracing

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Underground Space 2022年第4期7卷 498-513页

作者： Mingju Zhang zhitian Xie Pengfei Li Key Laboratory of Urban Security and Disaster Engineering Ministry of EducationBeijing University of TechnologyBeijing 100124China

A disconnectable coupling joint with double row wedges(DCJD)is a crucial component of the prestressed internal bracing in subway foundation ***,only a few studies have been conducted on the bearing capacity of the joints;moreover,the yield load and compression stiffness of DCJDs are typically determined from *** aim of this study was to quantitatively determine the bearing capacity and propose accurate formulas for calculating the yield load and compression stiffness of ***,a DCJD was selected from a foundation pit in Beijing,China,and loading experiments were conducted under axial ***–displacement and load–strain curves were obtained,and the failure modes of the joint were *** experimental results were verified through several finite element ***,parametric analyses were performed to investigate the effects of the dimensions of the key position on the DCJD’s bearing ***,regression analysis was used to obtain the formulae for estimating the initial compression stiffness and yield load of the ***,the fitting formulae results were compared with the numerical and experimental *** comparisons showed that the fitting formulae were highly accurate in estimating the bearing capacity of the DCJD.

关键词： Deep foundation pit Disconnectable coupling joints Loading experiments Parametric study Formulae fitting

Traveler’s Willingness to Accept and Provide Carpooling Services:A Case Study in Beijing

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Journal of Systems Science and Information 2020年第4期11卷 356-366页

作者： Lingling XIAO zhitian ZHOU School of Economics and Management Beijing Jiaotong University Beijing 100044 China

Carpooling as a transportation demand management(TDM) tool is currently being prevalent in major Chinese cities and producing much diminishment in the frequency of solo-driving ***, much disputes relating to carpooling is arising. To better understand the acceptance and the influence factors of carpooling, this paper investigates travelers’ willingness to provide and accept carpooling services. Firstly, a questionnaire survey was conducted. Secondly, we proposed a theoretical model, both car-owners and non-car-owners were sampled as respondents, and a multi-variable regression method was employed to analyze the survey data. Finally, we found that the higher acceptance,the more positive reactions to carpooling. The results indicate that it is necessary to improve the public’s acceptance of carpooling, because lower acceptance will lead to more negative reactions towards the carpooling, which may weaken its effectiveness.

关键词： Services acceptance driving