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Nonlinear Flap-Wise Vibration Characteristics ofWind Turbine Blades Based onMulti-Scale AnalysisMethod

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Energy Engineering 2024年第2期121卷 483-498页

作者： Qifa Lang Yuqiao zheng Tiancai Cui chenglong Shi Heyu Zhang School of Mechanical and Electrical Engineering Lanzhou University of TechnologyLanzhou730050China

This work presents a novel approach to achieve nonlinear vibration response based on the Hamilton principle.We chose the 5-MW reference wind turbine which was established by the National Renewable Energy Laboratory(NREL),to research the effects of the nonlinear flap-wise vibration characteristics.The turbine wheel is simplified by treating the blade of a wind turbine as an Euler-Bernoulli beam,and the nonlinear flap-wise vibration characteristics of the wind turbine blades are discussed based on the simplification first.Then,the blade’s large-deflection flap-wise vibration governing equation is established by considering the nonlinear term involving the centrifugal force.Lastly,it is truncated by the Galerkin method and analyzed semi-analytically using the multi-scale analysis method,and numerical simulations are carried out to compare the simulation results of finite elements with the numerical simulation results using Campbell diagram analysis of blade vibration.The results indicated that the rotational speed of the impeller has a significant impact on blade vibration.When the wheel speed of 12.1 rpm and excitation amplitude of 1.23 the maximum displacement amplitude of the blade has increased from 0.72 to 3.16.From the amplitude-frequency curve,it can be seen that the multi-peak characteristic of blade amplitude frequency is under centrifugal nonlinearity.Closed phase trajectories in blade nonlinear vibration,exhibiting periodic motion characteristics,are found through phase diagrams and Poincare section diagrams.

关键词： Wind turbine blades nonlinear vibration Galerkin method multi-scales method

Sensitive humidity sensor based on moisture-driven energy generation

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Nano Research 2024年第6期17卷 5578-5586页

作者： Qingchao Ni Qing Lou chenglong Shen Guangsong zheng Runwei Song Jingnan Hao Jialu Liu Jinyang Zhu Jinhao Zang Lin Dong Chong-Xin Shan Henan Key Laboratory of Diamond Optoelectronic Materials and Devices Key Laboratory of Materials PhysicsMinistry of Educationand School of Physics and MicroelectronicsZhengzhou UniversityZhengzhou 450052China State Centre for International Cooperation on Designer Low-Carbon&Environmental Materials and School of Materials Science and EngineeringZhengzhou UniversityZhengzhou 450001China

The emergence of novel self-powered humidity sensors has attracted considerable attention in the fields of smart electronic devices and personal healthcare.Herein,self-powered humidity sensors have been fabricated using a moisture-driven energy generation(MEG)device based on asymmetric tubular graphitic carbon nitride(g-CN)films prepared on anodized aluminum(AAO)template.At a relative humidity(RH)of 96%,the MEG device can provide an open-circuit voltage of 0.47 V and a short-circuit current of 3.51μA,with a maximum output power of 0.08μW.With inherent self-powered ability and humidity response via current variation,an extraordinary response of 1.78×106%(41%-96%RH)can be gained from the MEG device.The possible power generation mechanism is that g-CN/AAO heterostructure can form ion gradient and diffusion under the action of moisture to convert chemical potential into electrical potential,evoking a connaturally sensitive response to humidity.Self-powered respiration monitoring device based on the sensor is designed to monitor human movement(sitting,warming up,and running)and sleep status(normal,snoring,and apnea),maintaining excellent stability during cumulative 12-h respiration monitoring.This self-powered humidity sensing technology has promising potential for extensive integration into smart electronic and round-the-clock health monitoring devices.

关键词： graphitic carbon nitride moisture-driven energy generation humidity sensor respiration monitoring

Diverse terahertz wavefront manipulations empowered by the spatially interleaved metasurfaces

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Science China(Information Sciences) 2023年第3期66卷 230-238页

作者： Jitao LI Zhen YUE Jie LI chenglong zheng Silei WANG Mengyao LI Yating ZHANG Yan ZHANG Jianquan YAO School of Precision Instruments and Opto-Electronics Engineering Tianjin University College of Optoelectronic Engineering Chengdu University of Information Technology Department of Physics Capital Normal University

Optical metasurfaces have advanced approaches for manipulating light information in the spatial domain, in which the spatially interleaved metasurfaces demonstrate the ability to manipulate a more complex wavefront of light than metasurfaces without the spatial interleaving. The potential of the spatially interleaved metasurfaces has not been fully exploited. In this paper, we design the spatially interleaved terahertz(THz) metasurfaces based on the ingenious spatial interleaving principles to develop the diverse THz wavefront manipulations. Four functions are performed, including the orbital angular momentum(OAM)superposition of single-frequency vortex beams, the separate vortex focusing of single-frequency dual beams,the different OAM manipulations of bifrequency beams in different planes, and achromatic focusing. The demonstrated functions prove that the spatially interleaved metasurface can manipulate THz wavefront at both single frequency and bifrequency, which traditional metasurfaces cannot. This work paves the way for diverse THz wavefront manipulations.

关键词： terahertz wavefront manipulations metasurfaces spatial interleaving onformation optics

Dynamic phase assembled terahertz metalens for reversible conversion between linear polarization and arbitrary circular polarization

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Opto-Electronic Advances 2022年第1期5卷 24-34页

作者： Jitao Li Guocui Wang Zhen Yue Jingyu Liu Jie Li chenglong zheng Yating Zhang Yan Zhang Jianquan Yao Key Laboratory of Opto-Electronics Information Technology(Tianjin University) Ministry of EducationSchool of Precision Instruments and Opto-Electronics EngineeringTianjin UniversityTianjin 300072China Beijing Engineering Research Center for Mixed Reality and Advanced Display School of Optics and PhotonicsBeijing Institute of TechnologyBeijing 100081China Beijing Key Laboratory for Metamaterials and Devices Key Laboratory of Terahertz OptoelectronicsMinistry of Educationand Beijing Advanced Innovation Center for Imaging TechnologyDepartment of PhysicsCapital Normal UniversityBeijing 100048China

If a metalens integrates the circular polarization(CP)conversion function,the focusing lens together with circular-polariz-ing lens(CPL)in traditional cameras may be replaced by a metalens.However,in terahertz(THz)band,the reported metalenses still do not obtain the perfect and strict single-handed CP,because they were constructed via Pancharatnam-Berry phase so that CP conversion contained both left-handed CP(LCP)and right-handed CP(RCP)components.In this paper,a silicon based THz metalens is constructed using dynamic phase to obtain single-handed CP conversion.Also,we can rotate the whole metalens at a certain angle to control the conversion of multi-polarization states,which can simply manipulate the focusing for incident linear polarization(LP)THz wave in three polarization conversion states,in-cluding LP without conversion,LCP and RCP.Moreover,the polarization conversion behavior is reversible,that is,the THz metalens can convert not only the LP into arbitrary single-handed CP,but also the LCP and RCP into two perpen-dicular LP,respectively.The metalens is expected to be used in advanced THz camera,as a great candidate for tradi-tional CPL and focusing lens group,and also shows potential application in polarization imaging with discriminating LCP and RCP.

关键词： terahertz metalens metamaterials metasurfaces dynamic phase single-handed circular polarization reversible conversion

Broadband and tunable terahertz absorption via photogenerated carriers in undoped silicon

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Science China(Physics,Mechanics & Astronomy) 2022年第1期65卷 14-21页

作者： Jie Li Jitao Li chenglong zheng Longhai Liu Zhen Yue Hang Xu Xuanruo Hao Fuyu Li Tingting Tang Yating Zhang Jianquan Yao Key Laboratory of Opto-Electronics Information Technology(Tianjin University) Ministry of EducationSchool of Precision Instruments and Opto-Electronics EngineeringTianjin UniversityTianjin 300072China Advantest(China)Co. Ltd.Shanghai 201203China Information Materials and Device Applications Key Laboratory of Sichuan Provincial Universities Chengdu University of Information TechnologyChengdu 610225China

Terahertz absorbers based on doped silicon have achieved broadband and high-efficiency absorption due to their high concentration of carriers.However,their tunable performance is obviously insufficient.Here,we propose a new scheme for active terahertz absorption based on undoped silicon with a metamaterial antireflection layer,which realizes both strong absorption and ultrahigh modulation depth.Benefiting from the weak absorption and high transmission of undoped silicon for 1064-nm continuous wave,uniformly distributed carriers across the entire thickness of the absorber are excited,and efficient free carrier absorption of the terahertz wave is obtained.We use only a 500-μm thick absorber and achieve absorption greater than 90%in the range of 0.58 to 1.92 THz,with a peak value of 99%.More important,the absorber can be switched between two working states of nonabsorption and high-efficiency absorption by changing the pump power,which means the modulation depth reaches 100%.This simple and high-performance implementation scheme provides a new idea for the design of terahertz tunable absorbers.

关键词： terahertz carriers silicon metamaterials

Binary encoding-inspired generation of vector vortex beams

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Science China(Physics,Mechanics & Astronomy) 2023年第5期66卷 139-154页

作者： Hui Li chenglong zheng Jingyu Liu Hang Xu Chunyu Song Fan Yang Jitao Li Zhen Yue Wei Shi Yating Zhang Yan Zhang Jianquan Yao Key Laboratory of Opto-Electronics Information Technology(Tianjin University) Ministry of EducationSchool of Precision Instruments and Opto-Electronics EngineeringTianjin UniversityTianjin 300072China Beijing Key Laboratory for Metamaterials and Devices Key Laboratory of Terahertz OptoelectronicsMinistry of EducationBeijing Advanced Innovation Center for Imaging TechnologyDepartment of PhysicsCapital Normal UniversityBeijing 100048China

Vortex and vector terahertz(THz)beams with inhomogeneous polarization states have become a considerable hot topic in the last decade due to their important roles in multiplexed wireless data transmission.However,the technical instruments to form and evaluate such beams are rather limited,as they are mainly collected in the visible range.The emergence of coded metasurfaces has reinvigorated the design of functional devices with multiple degrees of freedom.Here,we demonstrate a versatile design inspired by a binary encoding approach for generating off-axis vectorial THz beams on all-silicon metasurfaces.Experimentally,simultaneous manipulation of the encoding method within the orthogonal circularly polarized(CP)channel provides strong support for developing versatility in vector THz beams,including the generation of arbitrary polarization profiles and the directional emission of multiplexed vector vortex beams(VVBs)with specified polarization states.The introduction of the latitudinal polarization control factor guarantees that continuously rotating or independently designed vector polarization profiles can be obtained on a pre-defined focal plane.Subsequently,a universal parametric theoretical model is developed to analyze the evolutionary trend of off-axis VVB in detail.Notably,the proposed monolayer vector metasurface bypasses the requirement of multiple cascaded optical elements,further inducing the advancement of ultra-thin vector THz sources,and also facilitating the generation of vector fields with tailored polarization distributions in 3D space.

关键词： metasurfaces vector beams spin-orbit interactions polarization optics

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面向超低空物流场景的多机协同航迹规划算法

系统仿真学报 2024年第1期36卷 50-66页

作者：程洁郑远李诚龙江波中国民用航空飞行学院空中交通管理学院四川广汉618307 中国民用航空飞行学院计算机学院四川广汉618307 北京航空航天大学电子信息工程学院北京100191

无人机产业的迅猛发展促进了低空开放,形成了国内外城市超低空物流运输的浪潮,然而,现有的航迹规划算法没有考虑空域的划分方式与运行规则,不适用于城市超低空物流场景下多无人机的协同航迹规划,桎梏了超低空物流行业的发展。针对该问题... 详细信息

无人机产业的迅猛发展促进了低空开放,形成了国内外城市超低空物流运输的浪潮,然而,现有的航迹规划算法没有考虑空域的划分方式与运行规则,不适用于城市超低空物流场景下多无人机的协同航迹规划,桎梏了超低空物流行业的发展。针对该问题,从实际需求出发,在空域高度层架构的基础上探索适用于城市超低空物流场景的多无人机协同航迹规划方法。将原问题分解为无人机-高度层任务分配与多无人机单高度层协同航迹规划两个相互耦合的子问题,并分别运用基于知识图谱的任务分配解法与基于粒子群算法的改进人工势场法对两个子问题进行求解。仿真实验表明,该方法在求解单高度层协同航迹规划子问题中不但能够避免传统方法的固有缺陷,平均迭代次数相较于对比方法也减少了62.09%;同时,仿真结果也表明所提方法可以快速鲁棒的解决原问题,为城市超低空物流场景提供了切实可行的多机航迹规划方法。

关键词：航迹规划任务分配多无人机知识图谱人工势场粒子群算法

融合可解释机器学习的成品汽油调和配方质量预测评价与致因分析

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石油学报（石油加工） 2024年第1期40卷 126-136页

作者：李炜郑明杰李亚洁梁成龙兰州理工大学电气工程与信息工程学院甘肃兰州730050 甘肃省工业过程先进控制重点实验室甘肃兰州730050 兰州理工大学电气与控制工程国家级实验教学示范中心甘肃兰州730050 中国石油兰州石化分公司油品储运厂甘肃兰州730060

受成品汽油调和配方需“先验”评价与修正的驱动,本研究将轻量级梯度提升树(LightGBM)与可解释机器学习(SHAP)方法相结合,兼顾复杂模型精度高与后验SHAP可解释性强的各自优势,提出了一种调和配方质量预测评价及致因分析方法。该方法先... 详细信息

受成品汽油调和配方需“先验”评价与修正的驱动,本研究将轻量级梯度提升树(LightGBM)与可解释机器学习(SHAP)方法相结合,兼顾复杂模型精度高与后验SHAP可解释性强的各自优势,提出了一种调和配方质量预测评价及致因分析方法。该方法先引用改进遗传算法(IGA)优化LightGBM的超参数,建立了可同时预测成品汽油性能和环保指标的模型,并结合汽油国ⅥA标准与企业生产实际制定了配方质量评价标准,实现配方“先验”评价;再基于SHAP的全局和局部致因分析,对缺陷配方给出了易于操作的单变量定性修正建议。实验结果表明:相比于传统BP网络和随机森林(RF)、以及采用随机搜索和GA优化参数的LightGBM等模型,IGA_LightGBM模型可得到更全面和精准的预测指标,SHAP致因分析可给出契合实际的修正建议。该方法是智能算法代替人工的有益探索。

关键词：成品汽油调和配方质量评价可解释机器学习预测建模致因分析参数优化

Terahertz metasurface polarization detection employing vortex pattern recognition

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Photonics Research 2023年第12期11卷 2256-2263页

作者： chenglong zheng JINGYU LIU HUI LI MENGGUANG WANG HUAPING ZANG YAN ZHANG JIANQUAN YAO Key Laboratory of Material Physics Ministry of EducationSchool of Physics and MicroelectronicsZhengzhou UniversityZhengzhou 450052China Beijing Key Laboratory for Metamaterials and Devices Key Laboratory of Terahertz OptoelectronicsMinistry of Educationand Beijing AdvancedInnovation Center for Imaging TechnologyDepartment of PhysicsCapital Normal UniversityBeijing 100048China Key Laboratory of Opto-Electronics Information Technology(Tianjin University) Ministry of EducationSchool of Precision Instruments andOpto-Electronics EngineeringTianjin UniversityTianjin 300072China State Key Laboratory of Modern Optical Instrumentation College of Optical Science and EngineeringZhejiang UniversityHangzhou 310027China

The manipulation and detection of polarization states play a crucial role in the application of 6G terahertz communication.Nonetheless,the development of compact and versatile polarization detection devices capable of detecting arbitrary polarizations continues to be a challenging endeavor.Here,we demonstrate a terahertz polarization detection scheme by performing mode purity analysis and multidimensional analysis of the transmitted vortex field.The power of the proposed polarization recognition is verified by using three polarization trajectories,including linear polarizations,circular polarizations,and elliptical polarizations.Using the reconstructed complete polarization parameters,the detected polarization states are characterized using polarization ellipses,Poincarésphere,and full-Stokes parameters.The experimental results validate the power of this scheme in polarization detection.This scheme holds promise for applications in polarization imaging and terahertz communication.

关键词： polarization scheme pattern