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Lift system optimization for hover-capable flapping wing micro air vehicle

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Frontiers of Mechanical Engineering 2024年第3期19卷 61-75页

作者： Shengjie XIAO Yongqi shi Zemin WANG Zhe NI yuhang ZHENG Huichao DENG Xilun DING Department of Mechanical Engineering and Automation Beihang UniversityBeijing 100191China Department of Mechanical Engineering Tsinghua UniversityBeijing 100084China Shenzhen International Graduate School Tsinghua UniversityShenzhen 518055China

A key challenge is using bionic mechanisms to enhance aerodynamic performance of hover-capable flapping wing micro air vehicle(FWMAV).This paper presented a new lift system with high lift and aerodynamic efficiency,which use a hummingbird as a bionic object.This new lift system is able to effectively utilize the high lift mechanism of hummingbirds,and this study innovatively utilizes elastic energy storage elements and installs them at the wing root to help improve aerodynamic performance.A flapping angle of 154°is achieved through the optimization of the flapping mechanism parameters.An optimized wing shape and parameters are obtained through experimental studies on the wings.Consequently,the max net lift generated is 17.6%of the flapping wing vehicle’s weight.Moreover,energy is stored and released periodically during the flapping cycle,by imitating the musculoskeletal system at the wing roots of hummingbirds,thereby improving the energy utilization rate of the FWMAV and reducing power consumption by 4.5%under the same lift.Moreover,strength verification and modal analyses are conducted on the flapping mechanism,and the weight of the flapping mechanism is reduced through the analysis and testing of different materials.The results show that the lift system can generate a stable lift of 31.98 g with a wingspan of 175 mm,while the lift system weighs only 10.5 g,providing aerodynamic conditions suitable for high maneuverability flight of FWMAVs.

关键词： lift optimization flapping wing elastic energy hovering flapping mechanism

Channel-Feedback-Free Transmission for Downlink FD-RAN:A Radio Map Based Complex-Valued Precoding Network Approach

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China Communications 2024年第4期21卷 10-22页

作者： Zhao Jiwei Chen Jiacheng Sun Zeyu shi yuhang Zhou Haibo Xuemin(Sherman)Shen School of Electronic Science and Engineering Nanjing UniversityNanjing 210023China College of Information Science and Electronic Engineering Zhejiang UniversityHangzhou 310058China Department of Mathematics and Theories Peng Cheng LaboratoryShenzhen 518000China Department of Electrical and Computer Engineering University of WaterlooWaterlooOntarioN2L 3G1Canada

As the demand for high-quality services proliferates,an innovative network architecture,the fully-decoupled RAN(FD-RAN),has emerged for more flexible spectrum resource utilization and lower network costs.However,with the decoupling of uplink base stations and downlink base stations in FDRAN,the traditional transmission mechanism,which relies on real-time channel feedback,is not suitable as the receiver is not able to feedback accurate and timely channel state information to the transmitter.This paper proposes a novel transmission scheme without relying on physical layer channel feedback.Specifically,we design a radio map based complex-valued precoding network(RMCPNet)model,which outputs the base station precoding based on user *** comprises multiple subnets,with each subnet responsible for extracting unique modal features from diverse input modalities.Furthermore,the multimodal embeddings derived from these distinct subnets are integrated within the information fusion layer,culminating in a unified representation.We also develop a specific RMCPNet training algorithm that employs the negative spectral efficiency as the loss function.We evaluate the performance of the proposed scheme on the public DeepMIMO dataset and show that RMCPNet can achieve 16%and 76%performance improvements over the conventional real-valued neural network and statistical codebook approach,respectively.

关键词： beamforming complex neural networks deep learning FD-RAN

Casein kinase-2 inhibition promotes retinal ganglion cell survival after acute intraocular pressure elevation

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Neural Regeneration Research 2024年第5期19卷 1112-1118页

作者： Meng Wang shi-Qi Yao Yao Huang Jia-Jian Liang Yanxuan Xu Shaowan Chen yuhang Wang Tsz Kin Ng Wai Kit Chu Qi Cui Ling-Ping Cen Joint Shantou International Eye Center of Shantou University and The Chinese University of Hong Kong ShantouGuangdong ProvinceChina Shantou University Medical College ShantouGuangdong ProvinceChina Beijing Tongren Eye Center Beijing Tongren HospitalCapital Medical UniversityBeijingChina Department of Ophthalmology and Visual Sciences The Chinese University of Hong KongHong Kong Special Administrative RegionChina

Intraocular pressure elevation can induce retinal ganglion cell death and is a clinically reversible risk factor for glaucoma,the leading cause of irreversible blindness.We previously demonstrated that casein kinase-2 inhibition can promote retinal ganglion cell survival and axonal regeneration in rats after optic nerve injury.To investigate the underlying mechanism,in the current study we increased the intraocular pressure of adult rats to 75 mmHg for 2 hours and then administered a casein kinase-2 inhibitor(4,5,6,7-tetrabromo-2-azabenzimidazole or 2-dimethylamino-4,5,6,7-tetrabromo-1H-benzimidazole)by intravitreal injection.We found that intravitreal injection of 4,5,6,7-tetrabromo-2-azabenzimidazole or 2-dimethylamino-4,5,6,7-tetrabromo-1H-benzimidazole promoted retinal ganglion cell survival and reduced the number of infiltrating macrophages.Transcriptomic analysis showed that the mitogen activated protein kinase signaling pathway was involved in the response to intraocular pressure elevation but was not modulated by the casein kinase-2 inhibitors.Furthermore,casein kinase-2 inhibition downregulated the expression of genes(Cck,Htrsa,Nef1,Htrlb,Prph,Chat,Slc18a3,Slc5a7,Scn1b,Crybb2,Tsga10ip,and Vstm21)involved in intraocular pressure elevation.Our data indicate that inhibition of casein kinase-2 can enhance retinal ganglion cell survival in rats after acute intraocular pressure elevation via macrophage inactivation.

关键词： casein kinase-2 glaucoma intraocular pressure elevation macrophages retinal ganglion cells

Reliability and validity of the hidden hunger assessment scale in China-revised for high school students

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Global Health Journal 2023年第2期7卷 110-116页

作者： Ning Zhang Minao Wang Yuchen Zhang Huake Cao Yang Yang yuhang shi Yang Pei Feixiang Yang Yinan Du School of Basic Medical Sciences Anhui Medical UniversityHefeiAnhui 230032China First School of Clinical Medicine Anhui Medical UniversityHefeiAnhui 230032China First Affiliated Hospital of Anhui Medical University HefeiAnhui 230022China Second School of Clinical Medicine Anhui Medical UniversityHefeiAnhui 230032China

Objective:Hidden hunger remains a severe public health problem that affects millions of people worldwide.In China,challenges related to dietary imbalance and hidden hunger persist.Micronutrient inadequacy deserves more attention among adolescents,given its vital role in their growth and development;however,this problem appears to have been largely ignored.High school students,in particular,are often at a high risk of hidden hunger but have limited assessment tools available.Therefore,this study aims to revise the hidden hunger assessment scale for high school students(HHAS-HSS)in China and assess its reliability and validity.Methods:Based on a literature review,expert consultation,pre-experiment,and formal survey,a hidden hunger assessment scale was revised for high school students.The formal survey involved 9336 high school students in 11 of the 16 cities in Anhui Province,China,and 9038 valid questionnaires were collected and included in the analysis.The item analysis,internal consistency reliability,test-retest reliability,content validity,exploratory factor analysis,and confirmatory factor analysis of the HHAS-HSS were examined.Results:The HHAS-HSS included a total of 4 dimensions and 12 items:"vegetables and food diversity"(three items),"fruits and dairy products"(three items),"micronutrient-dense foods"(four items),and"health condition and eating habits"(two items).The results showed a Cronbach's alpha of 0.758,a split-half reliability of 0.829,and a test-retest reliability of o.793,indicating good internal consistency.Using the Bartlett's test and Kaiser-Meyer-Olkin test(KMO)to test the exploratory factor analysis presented a four-factor model of the HHAS-HSS,the KMO0 value was 0.820(P<0.001),which indicated the possibility for factor confirmatory factor analysis.Using the maximum variance rotation method,four factors were obtained,and the cumulative variance explained rate was 57.974%.Confirmatory factor analysis also supported the division of the scale into four dimensions,and the fitting indices were x^

关键词： Hidden hunger Reliability and validity Assessment scale High school student Micronutrients

P掺杂煤沥青基多孔炭的制备及对废水中广谱抗生素的吸附性能

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高等学校化学学报 2024年第4期45卷 113-124页

作者：余谟鑫史文旭孙宇航张晨王晓婷安徽工业大学化学与化工学院马鞍山243000 中钢天源股份有限公司马鞍山243000 马钢集团股份有限公司马鞍山243000

以煤沥青为碳源,一水合次亚磷酸钠为磷源,氧化镁为模板耦合KOH活化,采用一步法制备了多孔炭(CPC_(x));并采用扫描电子显微镜、氮气吸附-脱附仪、傅里叶变换红外光谱和X射线光电子能谱等对炭材料进行了表征,考察了CPC_(x)对土霉素和氯霉... 详细信息

以煤沥青为碳源,一水合次亚磷酸钠为磷源,氧化镁为模板耦合KOH活化,采用一步法制备了多孔炭(CPC_(x));并采用扫描电子显微镜、氮气吸附-脱附仪、傅里叶变换红外光谱和X射线光电子能谱等对炭材料进行了表征,考察了CPC_(x)对土霉素和氯霉素的吸附性能.结果表明,当煤沥青与磷源的质量比为2∶1时,制得的CPC_(2.0)总比表面积和微孔比表面积分别为2739和2353 m^(2)/g,平均孔径为3.78 nm;苯基吸收峰有所加深,出现新的P—O伸缩振动峰;碳材料表面的磷及磷构型中最稳定的C_(3)—P=O官能团含量分别达0.45%和37.7%(摩尔分数);Langmuir模型和拟二级动力学模型能更好地描述CPC_(2.0)对抗生素的吸附过程,CPC_(2.0)对土霉素和氯霉素的最大吸附容量分别为1780和1122 mg/g,表现出优异的吸附性能.

关键词：多孔炭吸附磷掺杂抗生素

青藏高原东北缘及邻区岩石圈力学强度的贝叶斯估计

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地球物理学报 2024年第6期67卷 2220-2231页

作者：潘宇航陈石侍文孙玉军李永波董冬辉中国地震局地球物理研究所北京100081 北京白家疃地球科学国家野外科学观测研究站北京100095 中国地质科学院北京100037

本文基于复合岩石圈挠曲均衡模型,利用布格重力异常和地形数据,采用重力导纳和相关函数联合反演方法,结合贝叶斯统计推理确定最优的岩石圈挠曲参数模型,获取了青藏高原东北缘岩石圈有效弹性厚度Te和载荷比F的空间分布特征及不确定性估计... 详细信息

本文基于复合岩石圈挠曲均衡模型,利用布格重力异常和地形数据,采用重力导纳和相关函数联合反演方法,结合贝叶斯统计推理确定最优的岩石圈挠曲参数模型,获取了青藏高原东北缘岩石圈有效弹性厚度Te和载荷比F的空间分布特征及不确定性估计.在此基础上,本文分析了各个构造单元的差异性及其与强震活动的关系,并利用热-流变结构等资料,给出了构造运动可能的深部动力源.研究结果显示:青藏高原东北缘及邻区F呈现大面积低值分布,说明其现今岩石圈挠曲状态主要与地表载荷加载相关.此外,岩石圈有效弹性厚度Te存在显著差异,其力学强度差异与青藏高原向东挤出变形、热结构状态有一定对应关系.本文结果可为定量化研究青藏高原动力学问题提供有效的地球物理依据.

关键词：青藏高原东北缘岩石圈挠曲有效弹性厚度载荷比贝叶斯估计

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具有低开关频率的感应电机无传感器控制

工程科学学报 2024年第3期46卷 491-502页

作者：齐昕任佳仕石向阳赵宇航李凌一北京科技大学机械工程学院北京100083 北京科技大学顺德创新学院佛山528399

着眼于传统低开关频率控制方法对无感磁链观测带来不利影响的问题,提出了一种具有低开关频率的感应电机无传感器控制方法.使用速度自适应滑模观测器与预测控制方法相结合,构成感应电机无传感器预测控制系统.其可以在较高采样频率下,有... 详细信息

着眼于传统低开关频率控制方法对无感磁链观测带来不利影响的问题,提出了一种具有低开关频率的感应电机无传感器控制方法.使用速度自适应滑模观测器与预测控制方法相结合,构成感应电机无传感器预测控制系统.其可以在较高采样频率下,有效降低开关频率,并保证系统具有较高的动态特性.同时,滑模思想的引入使观测器具有较强的鲁棒性.实验结果表明,所提出的低开关频率无传感器控制策略具有较高的控制精度和较强的抗干扰性能,研究的自适应滑模观测器在稳态和动态实验中均具有良好的观测精度,其中电流环响应时间可以达到1.52 ms,可以实现75 r·min^(–1)及以上转速范围内的稳定观测及运行,且系统最高平均开关频率保持在500 Hz上下,为较低的水平.

关键词：无传感器低开关频率电流预测型开关策略自适应滑模观测器感应电机

基于MPC-PIO的无人飞行器集群编队重构控制

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北京航空航天大学学报 2024年第5期50卷 1541-1550页

作者：廖剑高向阳闫实周绍磊王东来康宇航赣南师范大学物理与电子信息学院赣州341000 中国科学院深圳先进技术研究院深圳518055 海军航空大学航空基础学院烟台264001 北海舰队青岛266000

针对存在各种障碍条件下的战场环境,为实现无人飞行器集群安全避障并进行快速精确打击,集群必须具备自主队形重构的能力。因此,建立了无人飞行器运动模型与领航跟随集群编队控制结构,并提出基于模型预测控制(MPC)框架的无人飞行器集群... 详细信息

针对存在各种障碍条件下的战场环境,为实现无人飞行器集群安全避障并进行快速精确打击,集群必须具备自主队形重构的能力。因此,建立了无人飞行器运动模型与领航跟随集群编队控制结构,并提出基于模型预测控制(MPC)框架的无人飞行器集群编队重构控制代价函数、避障代价函数及避碰代价函数,进一步运用鸽群优化(PIO)算法对重构问题进行优化求解。基于数值对比仿真实验结果,所提算法在集群编队跟踪误差和寻优速度方面表现出色。结果表明:所提算法能实现集群自主重构,并提高MPC方法的效率。

关键词：无人飞行器集群编队重构控制模型预测控制鸽群优化避障

基于改进YOLO6D的单目位姿估计算法研究

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传感器与微系统 2024年第1期43卷 44-47,51页

作者：潘江任德均史雨杭王淋楠四川大学机械工程学院四川成都610065

针对当前基于单目RGB图像的杂乱场景中低纹理物体6D位姿估计算法精度不高、实时性不强、模型复杂等问题,提出了一种基于改进YOLO6D的物体位姿估计算法。用纯卷积神经网络ConvNeXt替换原算法的主干网络DarkNet—19,将网络输出经过空间金... 详细信息

针对当前基于单目RGB图像的杂乱场景中低纹理物体6D位姿估计算法精度不高、实时性不强、模型复杂等问题,提出了一种基于改进YOLO6D的物体位姿估计算法。用纯卷积神经网络ConvNeXt替换原算法的主干网络DarkNet—19,将网络输出经过空间金字塔池化(SPP)处理后上采样,与低层特征图拼接实现特征融合,以提高网络的特征提取能力和多尺度能力。基于Focal Loss改进损失函数以提升网络的学习能力。根据物体的先验尺寸信息和几何特征,推导出更多的2D—3D点对以提高透视投影变换PnP算法的解算精度。在LINEMOD数据集上进行了实验,实验结果表明:以2D重投影5像素阈值为指标,本文算法在12个实验对象上的平均精度达到了95.60%,相较原算法提升了8.14个百分点,耗时约为60ms,性能显著提升。

关键词： 6D位姿估计单目视觉 ConvNeXt PnP算法