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Observer-based robust control for a class of sampled-data systems with model uncertainty and external disturbance

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Journal of Control and Decision 2023年第3期10卷 454-463页

作者： Junqi Yang zechen li Yantao Chen School of Engineering and Automation Henan Polytechnic UniversityJiaozuoPeople’s Republic of China Henan Key Laboratory of Intelligent Detection and Control of Coal Mine Equipment Henan Polytechnic UniversityJiaozuoPeople’s Republic of China

This paper studies the issue of observer-based feedback stabilisation for a class of linear sampleddatasystems with model uncertainty and external disturbance. First, for a sampled-data systemwith external disturbance, a sampled-data observer is designed to estimate the system ***, a robust H∞ controller based on the observer is developed. For a continuous samplinginterval, the gain matrices of both observer and controller change exponentially. Second,using the state coordinate transformations with an exponential rate, a unified dynamics is constructedby augmenting the state estimation error and the closed-loop system state as a newstate. Next, the sufficient conditions ensuring the asymptotical stability of the closed-loop systemare given by the Lyapunov–Krasovskii method and linear matrix inequality (LMI) ***, the effectiveness of the proposed method is verified by a helicopter model.

关键词： Sampled-data system observer linear matrix inequality robust controller

Dual-photoconductivity in monolayer PtSe_(2) ribbons

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Nano Research 2024年第11期17卷 10189-10195页

作者： zechen li Honglin Wang Huaipeng Wang Jing li Fangzhu Qing Xuesong li Dan Xie Hongwei Zhu State Key Lab of New Ceramics and Fine Processing School of Materials Science and Engineering Tsinghua University Beijing 100084 China School of Integrated Circuits Beijing National Research Center for Information Science and Technology Tsinghua University Beijing 100084 China State Key Lab of Solid Waste Reuse for Building Materials Beijing Building Materials Academy of Science Research Beijing 100041 China Shenzhen Institute for Advanced Study University of Electronic Science and Technology of China Shenzhen 518110 China

Two-dimensional platinum diselenide (PtSe_(2)) has been explored for applications in visible and infrared photodetectors, owing to its tunable electrical and optoelectronic properties governed by layer-dependent bandgaps. Studies have explored both positive photoconductivity (PPC) and negative photoconductivity (NPC) behaviors in few-layer PtSe_(2) thin films, proposing mechanisms related to gas molecule adsorption. However, these proposed mechanisms, typically based on models with ideal limit structures, often lacked consistency with the structure and scale of polycrystalline thin films employed in actual experiments. Here, photodetectors utilizing monolayer PtSe_(2) ribbons were designed, demonstrating a significant NPC effect upon exposure to visible light in atmospheric conditions, with device resistance increasing to over threefold the initial state. Under vacuum conditions, the device demonstrated PPC characteristics. Density functional theory calculations indicated that oxygen molecules physically adsorbed at the edges of PtSe_(2) ribbons were integral. Laser irradiation prompted the detachment of oxygen molecules from the ribbon’s edges, leading to a decreased carrier concentration in channel conductivity. The abundant edge sites of the ribbons endowed the photodetectors with a pronounced NPC response. This study diverted from traditional multilayer PtSe_(2) films to explore monolayer PtSe_(2) ribbons. These ribbons, as limit structures, offered a more fundamental insight into the intrinsic photoconductivity properties of PtSe_(2). Photodetectors employing PtSe_(2) ribbons presented novel application prospects in low-power photodetection, gas detection, and additional fields.

关键词： platinum diselenide photodetector negative photoconductivity positive photoconductivity photoinduced desorption

Hydrophobic ionic liquid-in-polymer composites for ultrafast,linear response and highly sensitive humidity sensing

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Nano Research 2021年第4期14卷 1202-1209页

作者： Xuanliang Zhao Kanglin Zhou Yujia Zhong Peng liu zechen li Jialiang Pan Yu Long Meirong Huang Abdelrahman Brakat Hongwei Zhu State Key Lab of New Ceramics and Fine Processing School of Materials Science and EngineeringTsinghua UniversityBeijing 100084China Department of Electronic Engineering Tsinghua UniversityBeijing 100084China Department of Mechanical Engineering University of CaliforniaBerkeleyUSA

Traditional ionic liquids are sensitive to humidity but with long response time and nonlinear *** liquid-state ionic liquids are usually hard for dehydration which have ultralong response time for humidity *** immobilization of ionic liquids provide a possible way for high performance humidity *** materials and structures also promised faster response in humidity sensing,because of easier desorption of *** this work,we prepared flexible humidity sensitive composites based on hydrophobic ionic liquid and *** combination of hydrophobic ionic liquid with hydrophobic polymer realized linear response,high sensitivity with low hysteresis to *** adjusting the ratio of ionic liquid,not only the impedance but also the hydrophobicity of composite could be modulated,which had a significant influence on the humidity sensing *** morphology and microstructure of the material also affected its interaction with water *** to the diverse processing methods of polymer,highly transparent film fabricated by spinning-coating and nanofibrous membrane fabricated by electrospinning could be prepared and exhibited different response time,which could be used for different application ***,the fibrous membrane made with electrospinning method showed an ultrafast response and could distinguish up to 120 Hz humidity change,due to its fibrous structure with high specific surface *** humidity sensors with ultrafast,linear response and high sensitivity showed potential applications in human respiratory monitoring and flexible non-contact *** better show the multifunction of ionic liquid-polymer composite,as a proof of concept,we fabricated an integrated humidity sensitive color change device by utilizing lower ionic liquid content composite for sensing in the humidity sensing module and higher ionic liquid content composite as the electrolyte in the electrochromic module.

关键词： ionic liquid flexible humidity sensing ultrafast response hydrophobic

Controllable preparation and microwave absorption properties of shape anisotropic Fe_(3)O_(4) nanobelts

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Journal of Materiomics 2021年第5期7卷 957-966页

作者： Jialiang Pan Rujing Zhang Jun ling Min Wang zechen li Zhen Zhen limin He Hongwei Zhu State Key Lab of New Ceramics and Fine Processing School of Materials Science and EngineeringTsinghua UniversityBeijing100084China The First Scientific Research Institute of Wuxi Wuxi214035JiangsuChina Key Laboratory of Science and Technology on Advanced Corrosion and Protection for Aviation Material AECC Beijing Institute of Aeronautical MaterialsBeijing100095China

To substantially prevent electromagnetic threatens,microwave absorbing materials(MAMs)are required to eliminate surplus electromagnetic *** a typical MAM,Fe_(3)O_(4) particles with complex permittivity and permeability have been widely applied due to the coexistence of magnetic loss and dielectric ***,the necessary high mass fraction significantly limited its applications,thus Fe_(3)O_(4) nanostructures have been extensively investigated to overcome this *** this work,uniform Fe_(3)O_(4) nanobelts were prepared by electrospinning and two-step thermal *** controlling the composition and viscosity of the electrospinning precursor solution,Fe_(3)O_(4) nanobelts with tunable lateral sizes(200 nme1 mm)were *** samples with low content(only 16.7 wt%)Fe_(3)O_(4) exhibited wide maximum effective absorbing bandwidths(EAB)over 3 GHz,and Fe_(3)O_(4) nanobelts with smaller lateral sizes showed a maximum EAB of 4.93 ***,Fe_(3)O_(4) nanobelts with smaller lateral sizes presented superior reflection loss properties,the lowest reflection loss reached-53.93 dB at 10.10 GHz,while the maximum EAB was up to 2.98 *** excellent microwave reflection loss of Fe_(3)O_(4) nanobelts was contributed to the enhanced synergistic effect of magnetic loss,dielectric loss,and impedance matching,originated from the hierarchically cross-linked networks and shape *** study could broaden the practical applications of magnetic absorbers,and provided an approach for the development of shape anisotropic magnetic materials.

关键词： Fe_(3)O_(4) Nanobelts Shape anisotropy Microwave absorption Reflection loss

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鄂尔多斯盆地临兴区块测井含气量解释方法

煤炭学报 2018年第S2期43卷 490-498页

作者：李泽辰杜文凤胡进奎李冬中国矿业大学(北京)煤炭资源与安全开采国家重点实验室北京100083 中国矿业大学(北京)地球科学与测绘工程学院北京100083

煤层含气量不仅是煤层气储层综合评价的一个重要参数,同时,准确预测煤层含气量也是预防瓦斯爆炸事故的重要手段,因此准确确定煤层含气量是至关重要的。针对这一问题,以鄂尔多斯盆地东缘临兴区块为研究对象,结合前人研究成果,同时引入了... 详细信息

煤层含气量不仅是煤层气储层综合评价的一个重要参数,同时,准确预测煤层含气量也是预防瓦斯爆炸事故的重要手段,因此准确确定煤层含气量是至关重要的。针对这一问题,以鄂尔多斯盆地东缘临兴区块为研究对象,结合前人研究成果,同时引入了基于决策树模型的集成算法模型,依据研究区实测数据,分别建立了煤层含气量的SVM模型、神经网络模型、随机森林模型、梯度提升树模型4种预测模型,分析并对比了各模型的性能。结果表明,基于决策树模型的集成算法模型预测效果更好,稳定更强,在样本量较少、维度较低的样本集上比SVM模型和ANN模型更有优势。

关键词：煤层含气量预测支持向量机算法神经网络算法随机森林算法梯度提升树算法

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易学视野下的建筑风水研究

东岳论丛 2008年第5期29卷 50-52页

作者：董睿李泽琛山东大学土建与水利学院山东济南250014 山东三力建筑设计有限公司山东济南250100

易学视野下的"天人合一"的自然观、"保合太和"的和谐观、"方以类聚"的吉凶观、"精气为物"的气场观以及"辨方正位"的方位观是建筑风水研究的理论基础。风水观念作为中国传统建筑文化的重要组成部分,每时每刻都在影响着我们的生活。

关键词：易学建筑风水研究

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煤层瓦斯突出危险区综合预测方法

煤炭学报 2018年第2期43卷 466-472页

作者：李冬彭苏萍杜文凤邢朕国李泽辰中国矿业大学(北京)煤炭资源与安全开采国家重点实验室北京100083 中国矿业大学(北京)地球科学与测绘工程学院北京100083

常规的瓦斯突出预测技术,主要从单一角度出发,无法达到多因素影响下的瓦斯突出危险区域预测精度。以某研究区为例,利用基于遗传算法的支持向量机(SVM)网络,预测了瓦斯含量;将孔隙度作为构造煤的判别因子,并通过概率神经网络(PNN)反演方... 详细信息

常规的瓦斯突出预测技术,主要从单一角度出发,无法达到多因素影响下的瓦斯突出危险区域预测精度。以某研究区为例,利用基于遗传算法的支持向量机(SVM)网络,预测了瓦斯含量;将孔隙度作为构造煤的判别因子,并通过概率神经网络(PNN)反演方法,得到了构造煤分布情况;介绍了基于自然伽马曲线的拟密度反演方法,获得了煤层顶板岩性情况。综合瓦斯含量、构造煤分布及煤层顶板岩性3个方面特征,建立了一套瓦斯突出危险区域综合预测方法,为判断瓦斯突出危险区提供了理论基础。经过与实际突出位置做验证,预测结果吻合,说明了综合预测方法在此研究区具有较高的准确性。

关键词：瓦斯突出瓦斯含量构造煤顶板岩性综合预测

多尺度注意力学习的Faster R-CNN口罩人脸检测模型

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西南交通大学学报 2021年第5期56卷 1002-1010页

作者：李泽琛李恒超胡文帅杨金玉华泽玺西南交通大学信息科学与技术学院四川成都611756

针对在佩戴口罩等有遮挡条件下的人脸检测问题,提出了多尺度注意力学习的Faster R-CNN(MSAF R-CNN)人脸检测模型.首先,为充分考虑人脸目标多尺度信息,相较于原始Faster R-CNN框架,引入Res2Net分组残差结构,获取更细粒度的特征表征;其次... 详细信息

针对在佩戴口罩等有遮挡条件下的人脸检测问题,提出了多尺度注意力学习的Faster R-CNN(MSAF R-CNN)人脸检测模型.首先,为充分考虑人脸目标多尺度信息,相较于原始Faster R-CNN框架,引入Res2Net分组残差结构,获取更细粒度的特征表征;其次,基于空间-通道注意力结构改进的Res2Net模块,结合注意力机制自适应学习目标不同尺度特征;最后,为学习目标的全局信息并减轻过拟合现象,在模型顶端嵌入加权空间金字塔池化网络,采用由粗到细的方式进行特征尺度划分.在AIZOO和FMDD两个人脸数据集上的实验结果表明:所提出MSAF R-CNN模型对佩戴口罩的人脸检测准确率分别达到90.37%和90.11%,验证了模型的可行性和有效性.

关键词：口罩人脸深度学习注意力机制多尺度学习特征融合目标检测

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法国对非洲援助政策简析及启示

海外投资与出口信贷 2022年第1期 33-38页

作者：李则辰中国进出口银行主权客户部

法国与非洲有着特殊的历史渊源,法非合作关系密切,研究双方经贸合作历史及法援非政策体系,对我国更好开展对非洲合作具有借鉴意义。我国援非工作可从丰富援外产品、划分重点援助区域、加大文化宣传援助力度、突出绿色发展理念、加强与... 详细信息

法国与非洲有着特殊的历史渊源,法非合作关系密切,研究双方经贸合作历史及法援非政策体系,对我国更好开展对非洲合作具有借鉴意义。我国援非工作可从丰富援外产品、划分重点援助区域、加大文化宣传援助力度、突出绿色发展理念、加强与多边机构交流等方面加以完善。

关键词：法国非洲国家对非洲援助