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Reynolds-number scaling analysis on lift generation of a flapping and passive rotating wing with an inhomogeneous mass distribution

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Chinese Journal of Aeronautics 2024年第2期37卷 259-269页

作者： Suyang QIN Haotian HANG Yang XIANG Hong LIU J.C.Wu center for aerodynamics school of aeronautics and astronauticsshanghai jiao tong universityshanghai 200240china

Insects usually fly by passively rotating wings,which has been applied to the design of flapping-wing Micro-Air Vehicles(MAVs)to reduce mechanical *** this paper,a robotic passive rotating-wing model is designed to investigate wing kinematics and lift generation,which are measured by a high-speed camera and a force transducer,*** addition,flow fields are measured using the Particle Image Velocimetry(PIV).Experimental results demonstrate that passive rotating motion has a coordinative relationship with actively stroking *** the stroke amplitude or frequency increases,the rotating amplitude is *** characterize the active stroking motion,a driving Reynolds number Redrivingis defined,which varies from 68 to 366 in this *** the gravity center of the wing towards trailing ed ge induces the increase of additional torque M,which decreases the wing rotating amplitude and promotes the advance of wing *** find that the timing of wing rotation is gradually delayed and the mean lift coefficient C^(-)_(L)monotonously decreases as *** increasing the additional torque M,C^(-)_(L)is slightly improved and approaches to the lift coefficient of a real fruit fly at driving Re approximately equal to *** instantaneous lifts combined with the vortical structures further demonstrate that the lift generation associated with wing rotation is mainly attributed to the growth of the LeadingEdge Vortex(LEV)and the passive wake capture *** wake capture is influenced by LEV,reversal stroke motion and wing additional torque together,which can only maintain the lift at a high level for a considerable *** high-lift generation mechanisms of flapping and passive rotating flight could shed light on the simplified design of MAVs and the improvement of their aerodynamic performance.

关键词： Flapping flight Unsteady lift Passive rotation Vortex flow Leading-edge vortex

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Parametric“non-nested”discriminants for multiplicities of univariate polynomials

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science china Mathematics 2024年第8期67卷 1911-1932页

作者： Hoon Hong Jing Yang Department of Mathematics North Carolina State UniversityRaleighNC 27695USA SMS-HCIC-School of Mathematics and Physics Center for Applied Mathematics of GuangxiGuangxi Minzu UniversityNanning 530006China

We consider the problem of complex root classification,i.e.,finding the conditions on the coefficients of a univariate polynomial for all possible multiplicity structures on its complex *** is well known that such conditions can be written as conjunctions of several polynomial equalities and one inequality in the *** polynomials in the coefficients are called discriminants for *** is also known that discriminants can be obtained using repeated parametric greatest common *** resulting discriminants are usually nested determinants,i.e.,determinants of matrices whose entries are determinants,and so *** this paper,we give a new type of discriminant that is not based on repeated greatest common *** new discriminants are simpler in the sense that they are non-nested determinants and have smaller maximum degrees.

关键词： parametric polynomial complex roots discriminant multiplicity resultant

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Converting an O-vacancy-rich oxide into a multifunctional separator modifier for long-lifespan lithium metal batteries

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Journal of Energy Chemistry 2024年第10期97卷 371-378页

作者： Juntao Si Xiaoying Li Yixuan Li Kuo Cao Yiran Zhu Chunhua Chen CAS Key Laboratory of Precision and Intelligent Chemistry Department of Materials Science and Engineering University of Science and Technology of China

The lithium metal anode is hailed as the desired "holy grail" for the forthcoming generation of highenergy-density batteries,given its astounding theoretical capacity and low ***,the formation and growth of dendrites seriously compromise battery life and ***,an yttriastabilized bismuth oxide（YSB） layer is fabricated on the polypropylene（PP） separator,where YSB reacts with Li anode in-situ in the cell to form a multi-component composite interlayer consisting of Li3Bi,Li2O,and *** interlayer can function not only as a redistributor to regulate Li+distribution but also as an anion adsorber to increase the Li+transference number from 0.37 to 0.79 for suppressing dendrite nucleation and ***,compared with the cell with a baseline separator,those with modified separators exhibit prolonged lifespan in both Li/Li symmetrical cells and Li/Cu ***,the full cells coupled with ultrahigh-loading LiFePO4display an excellent cycling performance of 1700 cycles with a high capacity retention of ～80% at 1 C,exhibiting great potential for practical *** work provides a feasible and effective new strategy for separator modification towards building a much-anticipated dendrite-free Li anode and realizing long-lifespan lithium metal batteries.

关键词： Conversion-alloying reaction Dendrite-free Lithium metal battery Multifunctional interlayer Separator

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The Neurovascular Unit Dysfunction in the Molecular Mechanisms of Epileptogenesis and Targeted Therapy

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Neuroscience Bulletin 2024年第5期40卷 621-634页

作者： Xiuxiu Liu Ying Zhang Yanming Zhao Qian Zhang Feng Han Medical Basic Research Innovation Center for Cardiovascular and Cerebrovascular Diseases Ministry of EducationNanjing211166China International Joint Laboratory for Drug Target of Critical Illnesses School of PharmacyNanjing Medical UniversityNanjing211166China Institute of Brain science The Affiliated Brain Hospital of Nanjing Medical UniversityNanjing211166China Gusu School Nanjing Medical UniversitySuzhou Municipal HospitalThe Affiliated Suzhou Hospital of Nanjing Medical UniversitySuzhou210019China

Epilepsy is a multifaceted neurological syndrome characterized by recurrent,spontaneous,and synchronous *** pathogenesis of epilepsy,known as epileptogenesis,involves intricate changes in neurons,neuroglia,and endothelium,leading to structural and functional disorders within neurovascular units and culminating in the development of spontaneous *** current research on epilepsy treatments primarily centers around anti-seizure drugs,it is imperative to seek effective interventions capable of disrupting *** this end,a comprehensive exploration of the changes and the molecular mechanisms underlying epileptogenesis holds the promise of identifying vital biomarkers for accurate diagnosis and potential therapeutic *** early diagnosis and timely intervention is paramount,as it stands to significantly improve patient prognosis and alleviate the socioeconomic *** this review,we highlight the changes and molecular mechanisms of the neurovascular unit in epileptogenesis and provide a theoretical basis for identifying biomarkers and drug targets.

关键词： Epileptogenesis Neurovascular unit Molecular mechanisms Drug targets

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Epidermal visualized health monitoring system based on stretchable and washable TPU hybrid conductive microtextiles

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Rare Metals 2024年第7期43卷 3185-3193页

作者： Jing-Bo Yuan Zhi-Hong Feng Dong-Chan Li Yang Luo Yun-Lei Zhou School of Chemical Engineering Hebei University of Technology Engineering Research Center of Chemical Technology for Efficient Utilization of Seawater ResourcesMinistry of EducationTianjin 300401China national Key Laboratory of Application Specific Integrated Circuit Shijiazhuang050000China Department of Materials ETH Zürich8093 ZurichSwitzerland Hangzhou Institute of Technology Xidian UniversityHangzhou 311231China

Electronic textiles,an emerging class of electronic technology,offer exciting opportunities for seamless integration with the human *** applications have been developed based on electronic ***,researches on integrating multiple electronic textilebased devices are still *** this study,we present a system integrated with an electrocardiogram monitoring sensor and an electroluminescence device based on stretchable and washable conductive micro *** signal is acquired by an electrocardiograph amplifier and displayed by a dual-color electroluminescence device based on the processed *** integrated electronic device has excellent moisture permeability and comfort for long-term *** system reported in this study opens a new avenue for the application of electronic textiles in health monitoring,robotic prosthetics,and competitive sports.

关键词： Conductive microtextile Textile composite Electronic textile Electroluminescent displays

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A novel and promising engineering application of carbon dots:Enhancing the chloride binding performance of cement

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Chinese Chemical Letters 2024年第6期35卷 409-416页

作者： Wu-Jian Long Yang Yu Chuang He Guangdong Provincial Key Laboratory of Durability for Marine Civil Engineering Key Lab of Coastal Urban Resilient InfrastructureMOECollege of Civil and Transportation EngineeringShenzhen UniversityShenzhen 518060China

Corrosion of reinforcement induced by chloride invasion is extensively considered as the dominating deterioration mechanism of reinforced concrete(RC)structures,leading to serious safety hazards and tremendous economic ***,it still lacks well dispersive and cost-efficient nanomaterials to improve the anti-chloride-corrosion ability of RC ***,specific carbon dots(CDs)with high dispersity and low cost are deliberately designed,successfully prepared by hydrothermal processing,and then firstly applied to immensely enhance chloride binding performance of cement,thereby contributing to suppressing the corrosion of ***,the tailored CDs are composed of the carbon core with highly crystalline sp^(2)C structures and oxygen-containing groups connecting on the carbon core;The typical equilibrium test confirms that with respect to that of the blank cement paste,the chloride binding capacity of cement paste involving 0.2 wt%(by weight of cement)CDs is increased by 109% after 14-day exposure to 3 mol/L Na Cl solution;according to comprehensive analyses of phase compositions,the chloride binding mechanism of CDs-modified cement is rationally attributed to the fact that the incorporation of CDs advances the formation of calcium silicate hydrate(C-S-H)gels and Friedel's salt(Fs),thus enormously enhancing the physically adsorbed and chemically bound chloride ions of cement *** work not only firstly provides a novel high-dispersity and low-cost nanomaterial toward the durability enhancement of RC structures,but also broadens the application of CDs in the field of engineering,conducing to stimulating their industrialization development.

关键词： Carbon dots Chloride binding Cement Chloride binding mechanism Friedel’s salt

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Time-resolved characteristics of a nanosecond pulsed multi-hollow needle plate packed bed dielectric barrier discharge

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Plasma science and Technology 2024年第7期26卷 48-57页

作者：秦亮李瑶郭浩姜楠宋颖贾锐周雄峰袁皓杨德正 Key Laboratory of Materials Modification by Laser Ionand Electron Beams(Dalian University of Technology)Ministry of EducationDalian 116024People’s Republic of China School of Electrical Engineering Dalian University of TechnologyDalian 116024People’s Republic of China State Key Laboratory of Complex Electromagnetic Environment Effects on Electronics and Information System Luoyang 471003People’s Republic of China School of Physics and Materials Engineering Dalian Minzu UniversityDalian 116600People’s Republic of China

In this paper,self-designed multi-hollow needle electrodes are used as a high-voltage electrode in a packed bed dielectric barrier discharge reactor to facilitate fast gas flow through the active discharge area and achieve large-volume stable *** dynamic characteristics of the plasma,the generated active species,and the energy transfer mechanisms in both positive discharge(PD)and negative discharge(ND)are investigated by using fast-exposure intensified charge coupled device(ICCD)images and time-resolved optical emission *** experimental results show that the discharge intensity,number of discharge channels,and discharge volume are obviously enhanced when the multi-needle electrode is replaced by a multihollow needle *** a single voltage pulse period,PD mainly develops in a streamer mode,which results in a stronger discharge current,luminous intensity,and E/N compared with the diffuse mode observed in *** PD,as the gap between dielectric beads changes from 0 to250μm,the discharge between the dielectric bead gap changes from a partial discharge to a standing filamentary micro-discharge,which allows the plasma to leave the local area and is conducive to the propagation of surface *** ND,the discharge only appears as a diffusionlike mode between the gap of dielectric beads,regardless of whether there is a discharge ***,the generation of excited states N_(2)^(+)(B^(2)∑_(u)^(+))and N2(C^(3)Π_(u))is mainly observed in PD,which is attributed to the higher E/N in PD than that in ***,the generation of the OH(A^(2)∑^(+))radical in ND is higher than in *** is not directly dominated by E/N,but mainly by the resonant energy transfer process between metastable N_(2)(A^(3)∑_(u)^(+))and OH(X^(2)Π).Furthermore,both PD and ND demonstrate obvious energy relaxation processes of electron-to-vibration and vibration-to-vibration,and no vibration-to-rotation energy relaxation process is observed.

关键词： packed bed reactor multi-hollow needle electrodes positive and negative discharges optical emission spectra time-resolved images

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A Deepfake Detection Algorithm Based on Fourier Transform of Biological Signal

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Computers, Materials & Continua 2024年第6期79卷 5295-5312页

作者： Yin Ni Wu Zeng Peng Xia Guang Stanley Yang Ruochen Tan School of Electrical and Electronic Engineering Wuhan Polytechnic UniversityWuhan430023China School of Mathematics and Computer science Wuhan Polytechnic UniversityWuhan430048China Paul G.Allen School of Computer science and Engineering University ofWashingtonSeattleWA98195USA School of Computer science and Engineering University of CaliforniaSanDiegoCA92093USA

Deepfake-generated fake faces,commonly utilized in identity-related activities such as political propaganda,celebrity impersonations,evidence forgery,and familiar fraud,pose new societal *** current deepfake generators strive for high realism in visual effects,they do not replicate biometric signals indicative of cardiac *** this gap,many researchers have developed detection methods focusing on biometric *** methods utilize classification networks to analyze both temporal and spectral domain features of the remote photoplethysmography(rPPG)signal,resulting in high detection ***,in the spectral analysis,existing approaches often only consider the power spectral density and neglect the amplitude spectrum—both crucial for assessing cardiac *** introduce a novel method that extracts rPPG signals from multiple regions of interest through remote photoplethysmography and processes them using Fast Fourier Transform(FFT).The resultant time-frequency domain signal samples are organized into matrices to create Matrix Visualization Heatmaps(MVHM),which are then utilized to train an image classification ***,we explored various combinations of time-frequency domain representations of rPPG signals and the impact of attention *** experimental results show that our algorithm achieves a remarkable detection accuracy of 99.22%in identifying fake videos,significantly outperforming mainstream algorithms and demonstrating the effectiveness of Fourier Transform and attention mechanisms in detecting fake faces.

关键词： Deepfake detector remote photoplethysmography fast fourier transform spatial attention mechanism

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A flexible model-free tram signal priority method with a large coordination scope in china

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Transportation Safety and Environment 2024年第3期6卷 28-34页

作者： Shan Wang Shanghai Urban Construction Design and Research Institute No.3447 Dongfang RoadPudong DistrictShanghai 200125China

Tram systems with the advantages of reliable operation,comfort,low emissions and moderate capacity have been quite popular in recent years in ***,there are still problems with tram signal control(*** model,signal control strategies).In-depth analysis on existing operational issues of trams,calculation of two evaluation indexes,as well as a flexible model-free tram signal priority method were developed to deal with tram *** research in Songjiang District,Shanghai shows that:(1)The function of the green extension strategy is limited with c.a.10%tram priority improvement,while the optimal one can reach to 85%higher on average.(2)A scheme with a benefit for trams and with no negative impact,and even benefits,for general traffic can be realized.(3)The optimal solution is beneficial for intersections with a maximum c.a.70%amelioration with delay decreasing from 132.7 s/vehicle to 40.89 s/vehicle,or from 104.77 s/capita to 22.31 s/*** paper has great significance for the signal optimization and safety of tram systems,even the development of a comprehensive transportation system for a city.

关键词： tram signal priority large coordination scope model-free signal control average passenger delay average vehicle delay

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DLP:towards active defense against backdoor attacks with decoupled learning process

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Cybersecurity 2024年第1期7卷 122-134页

作者： Zonghao Ying Bin Wu State Key Laboratory of Information Security Institute of Information EngineeringChinese Academy of SciencesBeijingChina School of Cyber Security University of Chinese Academy of SciencesBeijingChina

Deep learning models are well known to be susceptible to backdoor attack,where the attacker only needs to provide a tampered dataset on which the triggers are *** trained on the dataset will passively implant the backdoor,and triggers on the input can mislead the models during *** study shows that the model shows different learning behaviors in clean and poisoned subsets during *** on this observation,we propose a general training pipeline to defend against backdoor attacks *** models can be trained from the unreli-able dataset by decoupling the learning process into three stages,i.e.,supervised learning,active unlearning,and active semi-supervised *** effectiveness of our approach has been shown in numerous experiments across various backdoor attacks and datasets.

关键词： Deep learning Backdoor attack Active defense

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