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Acta Mechanica Sinica 2015年第5期31卷 647-652页

作者： Ling-Cheng Kong Yuan-tai hu Department of Mechanics Huazhong University of Science and Technology

With introduction of the first-order strain-gradient of surface micro-beams into the energy density function,we developed a two-dimensional dynamic model for a compound quartz crystal resonator（QCR） system,consisting of a QCR and surface micro-beam *** frequency shift that was induced by micro-beams with consideration of strain-gradients is discussed in detail and some useful results are obtained,which have important significance in resonator design and applications.

关键词： Micro-beams Strain-gradient Quartz crystal resonator Frequency shift

Study on Satellite-to-ground Laser Communications with Existence of Atmosphere

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空间科学学报 2021年第3期41卷 505-510页

作者： LI hu hu tai SHAO Shiyong WU Pengfei National Space Science Center Chinese Academy of SciencesBeijing 100190 University of Chinese Academy of Sciences Beijing 100049 Anhui Institute of Optics and Fine Mechanics Chinese Academy of SciencesHefei 230031

The laser beam used to establish a communication channel between satellite and ground segments has a small divergence angle and a tiny spot on the Earth's surface,which may lead to the fail of the *** it's important to study the deflection of laser beam by the Earth's atmosphere and find a way to calibrate this *** theoretical analysis and real data processing method are used to obtain the mathematical model for divergence angle of laser communication beam and its correction *** the model has been applied to the data,which was used to describe the atmosphere state by traditional ground segments to obtain the critical elevation *** to the results of calculation,our conclusion will be that the correction should be done when the critical elevation happens.

关键词： Atmospheric deflection Laser communication Satellite-to-ground Correction

INTERACTION OF ELECTRIC CHARGES IN A PIEZOELECTRIC WITH RIGID EXTERNAL CRACKS

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Applied Mathematics and Mechanics(English Edition) 2005年第8期26卷 996-1006页

作者： hu Yuan-tai（胡太平） LI Guo-qing（李国清） JIANG Shu-nong（蒋树农） hu Hong-ping（胡洪平） YANG Jia-shi（杨嘉实） Institute of Mechanics and Sensing Technology Central South University Changsha 410083 P. R. China Depamnent of Mechanics Huazhong University of Science and Technology Wuhan 430074 P. R. China Depamnent of Engineering Mechanics University of Nebraska Lincoln NE68588 USA

Using Stroh＇s formalism the simple explicit expressions of Green＇s functions for a 2D piezoelectric body with two semi-infinite fixed conductor cracks subjected to a generalized line force were given. The Coulomb force acting on the free line charge aroused by the piezoelectricity and the distributed boundary polarization charges was discussed at first. Interactions between two singularities with free charge （s） located in a region with external cracks were studied, too. The numerical results show that the Coulomb force for two or more singularities with one free charge at least will have much influence on the electromechanical fields in piezoelectric media when these singularities move closely with each other and therefore cannot be overlooked again. The solutions obtained are valid not only for plane and anti-plane problems but also for coupled problems between in-plane and out-of-plane deformations.

关键词： external crack intensity factor Green ' s function Coulomb force

Crystal Structure of the Cytoplasmic Domain of the Type Ⅱ Secretion System Component EpsL of Vibrio parahaemolyticus

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Crystal Structure of the Cytoplasmic Domain of the Type Ⅱ S...

管状尖角台阶件局部加载过程分析及体积置换减压成形工艺

亚洲晶体学联合大会

作者： Nien-tai hu Institute of Biochemistry College of Life SciencesNational Chung Hsing University

＜正＞The type II secretion system （T2SS） is used for the translocation of fully folded extracellular proteins across the outer membrane of Gram-negative bacteria. At least 12 distinct protein components are require...

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塑性工程学报 2022年第7期29卷 26-32页

作者：胡福泰燕山大学机械工程学院河北秦皇岛066004 河北省轻量化装备设计制造创新中心河北秦皇岛066004

针对管状台阶零件挤压成形工艺的关键问题,对铝合金管状尖角台阶件挤压成形机理进行了全面分析研究,模拟分析了管状尖角台阶件的局部加载精密挤压成形过程。结果表明,三角形台阶顶点两侧材料流动时具有向相反方向翻转的特性。明确了变... 详细信息

针对管状台阶零件挤压成形工艺的关键问题,对铝合金管状尖角台阶件挤压成形机理进行了全面分析研究,模拟分析了管状尖角台阶件的局部加载精密挤压成形过程。结果表明,三角形台阶顶点两侧材料流动时具有向相反方向翻转的特性。明确了变形不协调和应力集中作用是造成角部开裂的主要原因,最终导致台阶高度难以增长。提出了体积置换法,消除了侧壁成形时的翻转效应,大幅度降低了台阶部位的成形压应力,提高了模具使用寿命,为管状尖角零件的局部大深度台阶挤压成形提供了可行途径。

关键词：精密挤压管状零件局部加载体积置换数值模拟

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ANALYSIS ON THE ELECTROMECHANICAL FIELDS IN A PIEZOELECTRIC SEMICONDUCTING NANOWIRE UNDER TORQUE DEFORMATION

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ANALYSIS ON THE ELECTROMECHANICAL FIELDS IN A PIEZOELECTRIC ...

基于梯度提升决策树的量子科学实验卫星光学实验预测

2016年全国压电和声波理论及器件应用研讨会

作者： Zhi-jian CUI Yuan-tai hu Shuai-qi FAN College of Petroleum Engineering Xi'an Shiyou University Department of Mechanics Huazhong University of Science and Technology

Background, Motivation and Objective Recently, much attention has been focused on piezoelectric semiconductors with the wurtzite construction, including Zn O, Ga N, In N, and Zn S, etc. Due to coupling of piezoelectric and semiconducting properties, nanowires and microwires of piezoelectric semiconductors have been used as basic building blocks for fabricating innovative devices, for example nanogenerators, piezoelectric diodes, piezoelectric field-effect transistors, piezoelectric chemical sensors, and piezo-phototropic devices. In general, when an open-circuit piezoelectric semiconducting structure is subjected to tension/compression, twist or bend deformations, redistribution of carriers will appear in the structure and a lot of electric charges will be accumulated on its surfaces;conversely, when a piezoelectric semiconducting structure is subjected to a voltage, there appear mechanically deformations together with redistribution of carriers. The above two phenomena are governed by the electromechanical coupling equations and the current movement equation. In this paper, we will discuss the electric potential, electric field, electric displacement distribution characteristics in a piezoelectric semiconducting nanowire(PSN) under the action of a torque. Statement of Contribution/Methods By assuming the PSN as transversely isotropic, the shear stress and strain components in the cross section of a PSN can be obtained in advance from the classical material mechanics, while the vanished curl of static electric fields has been used in the solution process. Based on the obtained shear stress and strain components, the electric potential, the electric field and the electric displacement in the PSN can be found from the piezoelectric governing equation. At the same time, the governing equation of carrier concentration can be deduced from the current balance condition. Finally, with the help of MATLAB, we calculate the distribution characteristics of electric potential,

关键词： Piezoelectric semiconductor Piezoelectric potential Carrier concentration

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空间科学学报 2020年第1期40卷 126-133页

作者：罗中凯李虎胡钛中国科学院国家空间科学中心北京100190 中国科学院大学北京100049

量子科学实验卫星在轨运行期间完成4种光学实验,地面监测人员通过遥测参数阈值判断卫星是否进行光学实验、实验类型及实验结果.这种方法需要预先设定大量阈值,并且这些阈值需要根据在轨卫星重新设定,可扩展性较差.针对以上问题,提出一... 详细信息

量子科学实验卫星在轨运行期间完成4种光学实验,地面监测人员通过遥测参数阈值判断卫星是否进行光学实验、实验类型及实验结果.这种方法需要预先设定大量阈值,并且这些阈值需要根据在轨卫星重新设定,可扩展性较差.针对以上问题,提出一种基于机器学习的光学实验判别方法,将量子科学实验卫星的光学实验监测任务抽象为机器学习中的多元分类问题,构建分类模型,利用量子科学实验卫星的真实历史遥测数据对模型进行训练,并通过真实实验计划对训练得到的模型进行验证.实验结果表明,本文提出的方法在没有专家先验知识的前提下,判别准确率达到99%,可用于量子科学实验卫星光学实验的实时监测任务.提出的基于机器学习的判别方法具有较强的可扩展性,可应用于卫星在轨运行的其他监测任务.

关键词：光学实验遥测数据机器学习阈值

基于LightGBM的HXMT在轨运行模式监测算法

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空间科学学报 2020年第1期40卷 109-116页

作者：李钰骙李虎胡钛中国科学院国家空间科学中心中国科学院大学

HXMT卫星的空间硬X射线巡天和定点观测计划切换频繁,需要对卫星有效载荷在轨状态进行实时监测和判别.目前采用的是地面监测人员根据总结的规则进行人工监测的方式,虽然执行方便,可解释性强,但人力消耗较大,且对规则之外的情况无法灵活处... 详细信息

HXMT卫星的空间硬X射线巡天和定点观测计划切换频繁,需要对卫星有效载荷在轨状态进行实时监测和判别.目前采用的是地面监测人员根据总结的规则进行人工监测的方式,虽然执行方便,可解释性强,但人力消耗较大,且对规则之外的情况无法灵活处理.本文利用HXMT卫星的实时遥测数据,提出一种基于LightGBM机器学习模型的在轨运行模式监测算法,将监测工作规约为多分类问题,并构建判别模型,对卫星在轨运行模式进行判断.在保障判别准确率的前提下,算法模型构建迅速,具有很高的实用性.基于真实遥测数据的试验表明,模型的判别准确率达到99.9%,满足在轨运行模式监测要求,可为HXMT卫星的运行监控任务提供参考依据.

关键词：在轨运行模式实时监测 LightGBM HXTM

Stereoselective Synthesis of (+)-Boronolide

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有机化学 2004年第Z1期24卷 243-页

作者： hu,Shou-Gang hu,tai-Shan WU,Yu-Lin State Key Laboratory of Bio-organic & Natural Products Chemistry Shanghai Institute of Organic Chemistry Chinese Academy of Sciences Shanghai 200032 State Key Laboratory of Bio-organic & Natural Products Chemistry Shanghai Institute of Organic Chemistry Chinese Academy of Sciences Shanghai 200032 State Key Laboratory of Bio-organic & Natural Products Chemistry Shanghai Institute of Organic Chemistry Chinese Academy of Sciences Shanghai 200032

　　(+)-Boronolide (1) and its deacetylated products have attracted much attention of synthetic chemists due to their diverse biological properties as well as their structural complexities.[1] Many of these reported synthesis involved dehydrogenation of δ-lactone by using benzeneseleninic anhydride or ring-closing olefin metathesis (RCM) to introduce the requisite α,β-unsaturated δ-lactone in boronolide. Here, we report the synthesis of boronolide with diastereoselective propargylation of α-hydroxy aldehyde as the key step and D-gluconolactone as the starting material.……

关键词： biological properties

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中心约束对比学习的自集成卫星异常检测方法

国防科技大学学报 2024年第6期46卷 33-42页

作者：郭国航李虎刘玉荣胡钛中国科学院国家空间科学中心北京100190 中国科学院大学北京100049

针对现有异常检测算法对遥测参数特征提取缺乏区分度以及异常决策信息丢失等问题,提出基于中心约束对比的自集成异常检测方法。融合对比损失和中心损失将正常样本映射到紧凑的特征分布,并采用多视角、多层次特征集成的方式实现样本的异... 详细信息

针对现有异常检测算法对遥测参数特征提取缺乏区分度以及异常决策信息丢失等问题,提出基于中心约束对比的自集成异常检测方法。融合对比损失和中心损失将正常样本映射到紧凑的特征分布,并采用多视角、多层次特征集成的方式实现样本的异常检测,提升了模型对卫星复杂工况的适应性。采用科学卫星真实遥测参数数据和基准数据集进行验证,结果表明,所提方法在真实遥测参数上比最优基准方法的F值提升21.8%,且具有更好的噪声抗干扰性。实验结果验证了方法的可行性,能够为卫星地面运管提供有效的判读支持。

关键词：科学卫星遥测参数对比学习异常检测