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Research of line-of-sight angle on aero-optic imaging deviation for vehicles flying at 40—60 km

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Optoelectronics Letters 2023年第4期19卷 242-247页

作者： XU liang ZHAO Shiwei WANG Tao Tianjin Key Laboratory of Complex Control Theory and Application School of Electronic Engineering and AutomationTianjin University of TechnologyTianjin 300384China Foreign Cooperation Projects Department PetroChina Dagang Oilfield CompanyTianjin 300280China

Aero-optical imaging deviation is a kind of optical effect,aiming at a conical aircraft.This paper analyzes the influence of the aircraft on the imaging deviation with the change of altitude and line-of-sight angle.In this paper,the relationships between imaging deviation and altitude as well as line-of-sight angle are analyzed,and the coupling relationship between altitude and line-of-sight angle is studied.We give the imaging deviation results of 5°—75°line-of-sight angle.The analysis shows that when the line-of-sight angle is in the range of 5°—35°,the imaging deviation is more sensitive,while the line-of-sight angle is in the range of 35°—75°,the imaging deviation is relatively flat,and the imaging deviation does not gradually decrease with the increase of line-of-sight angle,but there is a turning point in the middle of 5°—75°.The imaging deviation decreases first and then increases,and the turning point of line-of-sight angle is closely related to height.

关键词： deviation angle turning

Aero-optic imaging deviation prediction based on ISSA-ELM

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光电子快报:英文版 2023年第7期19卷 425-431页

作者： XU liang ZHAO Shiwei WANG Tao Tianjin Key Laboratory for Control Theory&Applications in Complicated Systems School of Electrical Engineering and AutomationTianjin University of TechnologyTianjin 300384China School of Intelligent Engineering Sun Yat-sen UniversityGuangzhou 510275China

When the aircraft is moving at high speed in the atmosphere,aero-optical imaging deviation will appear due to the influence of aero-optical effect.In order to achieve real-time compensation during the flight of the aircraft,it is necessary to analyze and predict the obtained imaging deviation data.In order to improve the search speed and accuracy of the prediction algorithm and the ability to jump out of local optimum,in this paper,an improved sparrow search algorithm optimized extreme learning machine(ISSA-ELM) neural network model is proposed to predict the aero-optical imagine deviation.Finally,the performance of ISSA-ELM,ELM neural network and SSA-ELM neural network was tested.The results showed that compared with ELM and SSA-ELM algorithms,the convergence speed of ISSA-ELM was significantly enhanced,and the accuracy of data prediction was also significantly improved.

关键词： effect. deviation extreme

HgaNets:Fusion of Visual Data and Skeletal Heatmap for Human Gesture Action Recognition

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Computers, Materials & Continua 2024年第4期79卷 1089-1103页

作者： Wuyan liang Xiaolong xu School of Internet of Things Nanjing University of Posts and TelecommunicationsNanjing210023China School of Computer Science Nanjing University of Posts and TelecommunicationsNanjing210023China

Recognition of human gesture actions is a challenging issue due to the complex patterns in both visual andskeletal features. Existing gesture action recognition (GAR) methods typically analyze visual and skeletal data,failing to meet the demands of various scenarios. Furthermore, multi-modal approaches lack the versatility toefficiently process both uniformand disparate input patterns.Thus, in this paper, an attention-enhanced pseudo-3Dresidual model is proposed to address the GAR problem, called HgaNets. This model comprises two independentcomponents designed formodeling visual RGB (red, green and blue) images and 3Dskeletal heatmaps, respectively.More specifically, each component consists of two main parts: 1) a multi-dimensional attention module forcapturing important spatial, temporal and feature information in human gestures;2) a spatiotemporal convolutionmodule that utilizes pseudo-3D residual convolution to characterize spatiotemporal features of gestures. Then,the output weights of the two components are fused to generate the recognition results. Finally, we conductedexperiments on four datasets to assess the efficiency of the proposed model. The results show that the accuracy onfour datasets reaches 85.40%, 91.91%, 94.70%, and 95.30%, respectively, as well as the inference time is 0.54 s andthe parameters is 2.74M. These findings highlight that the proposed model outperforms other existing approachesin terms of recognition accuracy.

关键词： Gesture action recognition multi-dimensional attention pseudo-3D skeletal heatmap

Recent advances in tip-enhanced Raman spectroscopy probe designs

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Nano Research 2023年第4期16卷 5555-5571页

作者： Da xu Boqun liang Yaodong xu Ming Liu Department of Electrical and Computer Engineering University of California-RiversideRiversideCalifornia 92521USA Materials Science and Engineering program University of California-RiversideRiversideCalifornia 92521USA

Tip-enhanced Raman spectroscopy(TERS)imaging is a super-resolution imaging technique that features the merits of both surface-enhanced Raman spectroscopy(SERS)and scanning probe microscopy(SPM),such as the high chemical sensitivity from the former and the nanoscale spatial resolution from the latter.These advantages make TERS an essential nanospectroscopic characterization technique for chemical analysis,materials science,bio-sensing,etc.TERS probes,the most critical factor determining the TERS imaging quality,are expected to provide a highly confined electromagnetic hotspot with a minimized scattering background for the generation of Raman signals with high spatial resolution.After two decades of development,numerous probe design concepts have been proposed and demonstrated.This review provides a comprehensive overview of the state-of-the-art TERS probe designs,from the working mechanism to the practical performance.We start with reviewing the recent development of TERS configurations and the corresponding working mechanisms,including the SPM platforms,optical excitation/collection techniques,and probe preparation methods.We then review the emerging novel TERS probe designs,including the remote-excitation probes,the waveguide-based nanofocusing probes,the metal-coated nanofocusing probes,the nanowire-assisted selective-coupling probes,and the tapered metal-insulator-metal probes.Our discussion focuses on a few critical aspects,including the surface-plasmon-polariton(SPP)hotspot excitation technique,conversion efficiency,working frequency,and controllability.In the end,we review the latest TERS applications and give a perspective on the future of TERS.

关键词： tip-enhanced Raman spectroscopy plasmonics scanning probe microscopy nanoscale imaging nanophotonics nanofocusing

A preliminary study on volatile organic compounds and odor in university dormitories:Situation,contribution,and correlation

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Building Simulation 2023年第3期16卷 379-391页

作者： Yibing Hu Ling xu Weihui liang School of Architecture and Urban Planning Nanjing University22 Hankou RoadNanjing 210093China

Many dormitories have a high population density,and occupants exposed to volatile organic compounds(VOCs)could suffer severe physical and mental issues,so it is important to ensure good indoor air quality(IAQ).Currently,indoor VOC analysis using only chemical concentration cannot accurately reflect the effect of odor on human comfort.Therefore,the sensory evaluation of indoor odor acts as a supplementary method for an IAQ assessment.Here,we measured indoor VOC concentrations in 10 dormitories under occupied and unoccupied conditions.The contribution of building materials and human-related emissions was analyzed.An odor activity value(OAV)was calculated using the VOC concentration and odorant threshold.In addition,recruited sensory odor panel members assessed the odor intensity of each dormitory and the correlation between odor intensity and chemical measurements was analyzed.The indoor total VOC(TVOC)concentration under occupied conditions ranged from 242.2 to 1063.1μg/m^(3),with a mean value of 454.1μg/m^(3).The TVOC concentration under unoccupied conditions varied from 97.2 to 1055.2μg/m^(3),with a mean value of 342.2μg/m^(3).The TVOC concentration of 90% of the dormitories under the two conditions met the national IAQ standards.An average of 53.6% indoor TVOC emissions are related to building materials,the outdoor-related TVOC concentration accounts for 15.7%,and the average human-related TVOC emissions are 1519.4μg/(h·person),which accounts for 30.7%.Compared to TVOC concentration,odor intensity-OAV(OAV_(sum),OAV_(max))could better characterize subjective and objective correlations.However,the goodness-of-fit is not satisfactory.Weber–Fencher's law has limitations in characterizing the correlation between odor intensity and OAV when applied to the indoor air mixture,based on this small-scale study.

关键词： indoor air quality volatile organic compounds odor activity value odor intensity sensory panel

Enhancement of laminar flow heat transfer with single/doubleinclined ribs for unilaterally-heated channel

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Science China(Technological Sciences) 2023年第7期66卷 2108-2118页

作者： WANG XiangYu xu XiangHua liang XinGang School of Aerospace Engineering Key Laboratory for Thermal Science and Power Engineering of Ministry of EducationTsinghua UniversityBeijing 100084China

To deal with the aerodynamic heating on the aircraft surface,a potential solution is to utilize liquid cooling via the channels in part of the fuselage.This is a typical problem of flow and heat transfer in channels with unilaterally-heated surfaces.The enhancement of heat transfer in the channel is significant due to the high heating flux.The optimal velocity and temperature fields are obtained first based on the field synergy optimization method.Four rib configurations are proposed to produce the longitudinal vortices suggested by the optimal velocity field.The flow and heat transfer characteristics of different rib configurations are obtained by numerical simulation.The numerical simulations show that the heat transfer enhancement of the rib configurations are quite different,but the pressure drop increases similarly in the laminar flow range of Re = 500–1500.The mechanism of heat transfer enhancement with the single/double-inclined ribs for the unilaterally-heated channel is analysed.The best enhancement of geometric parameter among the investigated parameters such as the angle,length,radius and the spacing of the ribs is obtained.

关键词： heat transfer enhancement field synergy optimization inclined ribs unilaterally-heated channel

Event-triggered tracking control for a class of nonholonomic systems in chained form

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Science China(Information Sciences) 2023年第7期66卷 147-161页

作者： liang xu Youfeng SU He CAI Center for Discrete Mathematics and Theoretical Computer Science Fuzhou University College of Computer and Data Science Fuzhou University School of Automation Science and Engineering South China University of Technology

In this study, the event-triggered asymptotic tracking control problem is considered for a class of nonholonomic systems in chained form for the time-varying reference input. First, to eliminate the ripple phenomenon caused by the imprecise compensation of the time-varying reference input, a novel time-varying event-triggered piecewise continuous control law and a triggering mechanism with a time-varying triggering function are developed. Second, an explicit integral input-to-state stable Lyapunov function is constructed for the time-varying closed-loop system regarding the sampling error as the external input. The origin of the closed-loop system is shown to be uniformly globally asymptotically stable for any global exponential decaying threshold signals, which in turn rules out the Zeno behavior. Moreover, infinitely fast sampling can be avoided by appropriately tuning the exponential convergence rate of the threshold signal. A numerical simulation example is provided to illustrate the proposed control approach.

关键词： event-triggered nonholonomic systems strict Lyapunov function tracking integral input-to-state stable

Elman neural network for predicting aero optical imaging deviation based on improved slime mould algorithm

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Optoelectronics Letters 2023年第5期19卷 290-295页

作者： XU liang WANG Luyang xuE Wei ZHAO Shiwei ZHOU Liye Tianjin Key Laboratory of Complex Control Theory and Application School of Electronic Engineering and AutomationTianjin University of TechnologyTianjin 300384China China Academy of Aerospace Science and Innovation Beijing 100048China

This research suggests a methodology to optimize Elman neural network based on improved slime mould algorithm(ISMA) to anticipate the aero optical imaging deviation.The improved Tent chaotic sequence is added to the SMA to initialize the population to accelerate the algorithm’s speed of convergence.Additionally,an improved random opposition-based learning was added to further enhance the algorithm’s performance in addressing problems that the SMA has such as weak convergence ability in the late iteration and an easy tendency to fall into local optimization in the optimization process when solving the optimization problem.Finally,the algorithm model is compared to the Elman neural network and the SMA optimization Elman neural network model.The three models are assessed using four evaluation indicators,and the findings demonstrate that the ISMA optimization model can anticipate the aero optical imaging deviation in an accurate way.

关键词： neural Elman network

Effect of Particle Size Distribution on Radiative Heat Transfer in High-Temperature Homogeneous Gas-Particle Mixtures

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Transactions of Nanjing University of Aeronautics and Astronautics 2019年第5期36卷 733-746页

作者： liang Dong HE Zhenzong XU liang MAO Junkui Aero-engine Thermal Environment and Structure Key Laboratory of Ministry of Industry and Information Technology College of Energy and Power EngineeringNanjing University of Aeronautics and Astronautics

The weighted-sum-of-gray-gas(WSGG)model and Mie theory are applied to study the influents of particle size on the radiative transfer in high temperature homogeneous gas-particle mixtures,such as the flame in aero-engine combustor.The radiative transfer equation is solved by the finite volume method.The particle size is assumed to obey uniform distribution and logarithmic normal(L-N)distribution,respectively.Results reveal that when particle size obeys uniform distribution,increasing particle size with total particle volume fraction fvunchanged will result in the decreasing of the absolute value of radiative heat transfer properties,and the effect of ignoring particle scattering will also be weakened.Opposite conclusions can be obtained when total particle number concentration N0 is unchanged.Moreover,if particle size obeys L-N distribution,increasing the narrowness indexσor decreasing the characteristic diameter Dˉwith the total particle volume fraction fvunchanged will increase the absolute value of radiative heat transfer properties.With total particle number concentration N0 unchanged,opposite conclusions for radiative heat source and incident radiation terms can be obtained except for radiative heat flux term.As a whole,the effects of particle size on the radiative heat transfer in the high-temperature homogeneous gas-particle mixtures are complicated,and the particle scattering cannot be ignoring just according to the particle size.

关键词： particle size distribution WSGG radiative heat transfer gas-particle mixtures