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A novel adaptive coordinated tracking control scheme for a morphing aircraft with telescopic wings

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Chinese Journal of Aeronautics 2024年第2期37卷 148-162页

作者： Enmei WANG Hao LU Jianchun ZHANG Chenliang WANG Jianzhong qiao Hangzhou Innovation Institute Beihang UniversityHangzhou 310051China School of Automation Science and Electrical Engineering Beihang UniversityBeijing 100191China

Inspired by flight biology,morphing flight technology has great potential to improve the adaptability and maneuverability of *** paper is devoted to the flight control problem of morphing aircraft,and aimed at safe and fuel-saving flight through morphing ***,the longitudinal dynamics of a morphing aircraft with telescopic wings is modelled as a strict-feedback nonlinear *** fitting the expression of aerodynamic parameters by the mor-phing ratio,the model uncertainties induced by morphing errors are embedded in the *** meet the safety and fuel-saving requirements,an Adaptive Coordinated Tracking Control Scheme(ACTCS)is then proposed,which consists of a morphing control module and a tracking control *** the morphing control module,an on-line morphing decision model is given in an optimization process with respect to the morphing ratio,and a second-order tracking filter is introduced to smooth the decision output and ensure the physical *** the tracking control module,the novel adaptive controllers for the velocity and altitude subsystems are proposed based on the dynamic surface control method,in which adaptive mechanisms are designed to com-pensate for the model ***,the proposed ACTCS is simulated in nine different cases of the test flight mission,to verify its effectiveness,robustness and fuel-saving effect.

关键词： Morphing aircraft Adaptive tracking control Morphing decision Dynamic surface control Morphing error

Towards kernelizing the classifier for hyperbolic data

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Frontiers of Computer Science 2024年第1期18卷 17-31页

作者： Meimei YANG qiao LIU Xinkai SUN Na SHI Hui XUE School of Computer Science and Engineering Southeast UniversityNanjing 210096China MOE Key Laboratory of Computer Science and Information Integration(Southeast University) Nanjing 210096China

Data hierarchy,as a hidden property of data structure,exists in a wide range of machine learning applications.A common practice to classify such hierarchical data is first to encode the data in the Euclidean space,and then train a Euclidean ***,such a paradigm leads to a performance drop due to distortion of data embedding in the Euclidean *** relieve this issue,hyperbolic geometry is investigated as an alternative space to encode the hierarchical data for its higher ability to capture the hierarchical *** methods cannot explore the full potential of the hyperbolic geometry,in the sense that such methods define the hyperbolic operations in the tangent plane,causing the distortion of data *** this paper,we develop two novel kernel formulations in the hyperbolic space,with one being positive definite(PD)and another one being indefinite,to solve the classification tasks in hyperbolic *** PD one is defined via mapping the hyperbolic data to the Drury-Arveson(DA)space,which is a special reproducing kernel Hilbert space(RKHS).To further increase the discrimination of the classifier,an indefinite kernel is further defined in the Krein ***,we design a 2-layer nested indefinite kernel which first maps hyperbolic data into the DA spaces,followed by a mapping from the DA spaces to the Krein *** experiments on real-world datasets demonstrate the superiority ofthe proposed kernels.

关键词： data hierarchy hyperbolic cgeometry drury-arveson space krein space

Smart Gait:A Gait Optimization Framework for Hexapod Robots

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Chinese Journal of Mechanical Engineering 2024年第1期37卷 146-159页

作者： Yunpeng Yin Feng Gao qiao Sun Yue Zhao Yuguang Xiao State Key Laboratory of Mechanical System and Vibration School of Mechanical EngineeringShanghai Jiao Tong UniversityShanghai 200240China Lenovo Corporation ShanghaiChina AI Institute School of Electronic Information and Electrical EngineeringShanghai Jiao Tong UniversityShanghai 200240China

The current gait planning for legged robots is mostly based on human presets,which cannot match the flexible characteristics of natural *** paper proposes a gait optimization framework for hexapod robots called Smart *** Gait contains three modules:swing leg trajectory optimization,gait period&duty optimization,and gait sequence *** full dynamics of a single leg,and the centroid dynamics of the overall robot are considered in the respective *** Smart Gait not only helps the robot to decrease the energy consumption when in locomotion,mostly,it enables the hexapod robot to determine its gait pattern transitions based on its current state,instead of repeating the formalistic clock-set step *** Smart Gait framework allows the hexapod robot to behave nimbly as a living animal when in 3D movements for the first *** Smart Gait framework combines offline and online optimizations without any fussy data-driven training procedures,and it can run efficiently on board in real-time after *** experiments are carried out on the hexapod robot *** results show that the energy consumption is reduced by 15.9%when in *** gait patterns can be generated spontaneously both in regular and challenge environments,and when facing external interferences.

关键词： Gait optimization Swing trajectory optimization Legged robot Hexapod robot

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稻草碎料/聚丙烯复合材料制备及性能研究

功能材料 2016年第11期47卷 11022-11026页

作者：郑霞袁光明乔建政唐钱朱凌波中南林业科技大学长沙410004

以稻草碎料和聚丙烯为主要原料,采用热压成型制备了稻草碎料增强聚丙烯复合材料,研究了NaOH改性剂浓度、稻草碎料质量分数以及热压温度对复合材料力学性能的影响。研究表明,8%NaOH处理可以去除稻草碎料中部分半纤维素,使稻草碎料表面变... 详细信息

以稻草碎料和聚丙烯为主要原料,采用热压成型制备了稻草碎料增强聚丙烯复合材料,研究了NaOH改性剂浓度、稻草碎料质量分数以及热压温度对复合材料力学性能的影响。研究表明,8%NaOH处理可以去除稻草碎料中部分半纤维素,使稻草碎料表面变得粗糙,有效改善了复合材料力学性能;稻草质量分数为40%时,聚丙烯可以有效包覆稻草碎料,复合材料拉伸强度和冲击强度的得到改善;热压温度为180℃时聚丙烯的流动性好,能改善稻草碎料在聚丙烯中分散的均匀性,且不会使聚丙烯热降解。此时,复合材料拉伸强度和冲击强度分别达到了最大值61.2 MPa和18.4kJ/m^2。

关键词：稻草碎料聚丙烯 NaOH预处理质量分数热压温度力学性能

Simultaneous enhancement of red luminescence and thermal stability of a novel red phosphor:A Li+-Eu3+ co-occupied site strategy in BaAl2Ge2O8 lattices

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Journal of Rare Earths 2024年第10期42卷 1846-1854页

作者： Wei Zhang Changjian Wang Xusheng qiao Xianping Fan State Key Laboratory of Silicon Materials School of Materials Science and EngineeringZhejiang University Ocean Academy Zhejiang University

The rapid development of phosphor-converted white light emitting diodes（pc-WLEDs） requires new red phosphors with efficient and thermally stable luminescence for high-quality warm-white ***,it is still a challenge to discover red phosphors with facile synthesis,high internal quantum efficiency（IQE）,excellent thermal stability and high color ***,a novel red-emitting Eu3+activated barium dialuminum digermanate（BaAl2Ge3O8,EAGO） phosphor showing strong red emission at 610 nm was *** IQE is improved from 32.91% to 78.84% by employing a charge compensation *** lithium-ion co-dop ed BAGO:Eu3+phosphor exhibits a nearly twofold increase in integral photoluminescence（PL） intensity and the high color purity reaches 94.17%.Impressively,the PL intensity of the BAGO:Eu3+,Li+phosphor drops by only 2.6% at 150℃ of that at room ***,the pc-WLED using the red BAGO:Eu3+,Li+phosphor exhibits white light with the chromaticity coordinate of（0.3515,0.3495）,a high color-rendering index of 92 and a low correlated color temperature of 4746 *** these results manifest that BAGO:Eu3+,Li+phosphor is a suitable red phosphor for nearultraviolet（NUV） chip-based pc-WLEDs.

关键词： Red phosphor Charge compensation High quantum efficiency Excellent thermal stability Rare earths

Ultra-low loss Rayleigh scattering enhancement via light recycling in fiber cladding

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Photonics Research 2024年第08期12卷 1813-1819页

作者： PENGTAO Luo FENGYI CHEN RUOHUI WANG XUEGUANG qiao School of Physics Northwest University Engineering Research Center of Optical Fiber Well Logging Technology for Oil and Gas Resources Universities of Shaanxi Province

Rayleigh backscattering enhancement(RSE) of optical fibers is an effective means to improve the performance of distributed optical fiber sensing. Femtosecond laser direct-writing techniques have been used to modulate the fiber core for RSE. However, in-core modulation loses more transmission light, thus limiting the sensing *** this work, a cladding-type RSE(cl-RSE) structure is proposed, where the femtosecond laser is focused in the fiber cladding and an array of scatterers is written parallel to the core. The refractive-index modulation structure redistributes the light in the cladding, and the backward scattered light is recovered, which enhances the Rayleigh backscattered signal with almost no effect on the core light.

关键词： Femtosecond lasers Optical fibers Optical signal to noise ratio Rayleigh scattering Ultrafast lasers Ultraviolet lasers

Simulation of Underground Reservoir Stability of Pumped Storage Power Station Based on Fluid-Structure Coupling

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Computer Modeling in Engineering & Sciences 2024年第5期139卷 1381-1399页

作者： Peng qiao Shuangshuang Lan Hongbiao Gu Zhengtan Mao Faculty of Architecture Civil and Transportation EngineeringBeijing University of TechnologyBeijing100020China College of Transportation Engineering Nanjing Tech UniversityNanjing210000China

Based on global initiatives such as the clean energy transition and the development of renewable energy,the pumped storage power station has become a new and significant way of energy storage and regulation,and its construction environment is more complex than that of a traditional *** particular,the stability of the rock strata in the underground reservoirs is affected by the seepage pressure and rock stress,which presents some challenges in achieving engineering safety and *** the advantages of the numerical simulation method in dealing deal with nonlinear problems in engineering stability,in this study,the stability of the underground reservoir of the Shidangshan(SDS)pumped storage power station was numerically calculated and quantitatively analyzed based on fluid-structure coupling theory,providing an important reference for the safe operation and management of the underground ***,using the COMSOL software,a suitablemechanicalmodel was created in accordance with the geological structure and project characteristics of the underground ***,the characteristics of the stress field,displacement field,and seepage field after excavation of the underground reservoir were simulated in light of the seepage effect of groundwater on the nearby rock of the underground ***,based on the construction specifications and Molar-Coulomb criterion,a thorough evaluation of the stability of the underground reservoir was performed through simulation of the filling and discharge conditions and anti-seepage strengthening *** findings demonstrate that the numerical simulation results have a certain level of reliability and are in accordance with the stress measured in the project *** underground reservoir excavation resulted in a maximum displacement value of the rock mass around the caverns of 3.56 mm in a typical section,and the safety coefficient of the parts,as determined using the Molar-Coulomb criterion,was highe

关键词： Underground reservoir fluid-structure coupling numerical simulation pumped storage power station filling and discharge

Almost periodic solutions of memristive multidirectional associative memory neural networks with mixed time delays

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International Journal of Biomathematics 2024年第2期17卷 113-138页

作者： Yan Zhang Yuanhua qiao Lijuan Duan Faculty of Science Beijing University of Technology Beijing 100124P.R.China Faculty of Information Technology Beijing University of Technology Beijing 100124P.R.China

Traditional biological neural networks cannot simulate the real situation of the abrupt synaptic connections between neurons while modeling associative memory of human *** this paper,the memristive multidirectional associative memory neural networks(MAMNNs)with mixed time-varying delays are investigated in the sense of Filippov ***,three steps are given to prove the existence of the almost periodic *** new lemmas are proposed to prove the boundness of the solution and the asymptotical almost periodicity of the solution by constructing Lyapunov ***,the uniqueness and global exponential stability of the almost periodic solution of memristive MAMNNs are investigated by a new Lyapunov *** sufficient conditions guaranteeing the properties of almost periodic solution are derived based on the relevant definitions,Halanay inequality and Lyapunov *** investigation is an extension of the research on the periodic solution and almost periodic solution of bidirectional associative memory neural ***,numerical examples with simulations are presented to show the validity of the main results.

关键词： Almost periodic solutions memristive multidirectional associative memory neural networks mixed time-varying delays global exponential stability

A hybrid attention model based on first-order statistical features for smoke recognition

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Science China(Technological Sciences) 2024年第3期67卷 809-822页

作者： GUO Nan LIU JiaHui DI KeXin GU Ke qiao JunFei Beijing Laboratory of Smart Environmental Protection Beijing Key Laboratory of Computational Intelligence and Intelligent SystemBeijing Artificial Intelligence InstituteBeijing 100124China Faculty of Information Technology Beijing University of TechnologyBeijing 100124China

Smoke and fire recognition are of great importance on foreseeing fire disasters and preventing environmental pollution by monitoring the burning process of objects(e.g., straw, fuels). However, since fire images suffer from problems like the variability of the features, complexity of scenarios, interference from background, changeable weather conditions as well as image quality problems, identifying smoke and fire accurately and promptly from a given image still remains a substantial challenge. Automatically learning the features of smoke images by CNNs has improved the target recognition ability compared to traditional approaches,nonetheless, convolutions and pooling operations in CNNs may cause severe information loss which may lead to *** tackle the above problems, this paper proposed a hybrid attention model based on the characteristics of smoke images. This model adopted multiple optimized attention mechanism in several stages to quickly and precisely capture the important features,achieving state-of-the-art performance on smoke and fire recognition in terms of accuracy and speed. Our proposed module mainly consists of two stages: pooling and attention. In the first stage, we conducted several newly proposed first-order pooling methods. Through traversing the data space in a larger scope, features are better reserved, thus constructing a more intact feature space of smoke and fire in an image. In the second stage, feature maps are aggregated together to perform channel and spatial attention. The channel and spatial dependencies allow us to quickly catch the important features presented in an image. By fully exploring the feature space and prominent salient features, characteristics of smoke and fire are better presented so as to obtain better smoke and fire detection results. Experiments have been conducted on public smoke detection dataset and new proposed fine-grained smoke and fire detection database. Experimental results revealed that the propose

关键词： hybrid attention first-order pooling smoke and fire detection deep convolutional neural networks