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Unmanned Ship Identification Based on Improved YOLOv8s Algorithm

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Computers, Materials & Continua 2024年第3期78卷 3071-3088页

作者： Chun-Ming wu Jin Lei wu-Kai Liu Mei-Ling ren Ling-Li Ran Key Laboratory of Modern Power System Simulation and Control&renewable Energy Technology School of Electrical EngineeringNortheast Electric Power UniversityJilin132012China School of Biomedical Engineering Taiyuan University of TechnologyTaiyuan030600China

Aiming at defects such as low contrast in infrared ship images,uneven distribution of ship size,and lack of texture details,which will lead to unmanned ship leakage misdetection and slow detection,this paper proposes an infrared ship detection model based on the improved YOLOv8 algorithm(R_YOLO).The algorithm incorporates the Efficient Multi-Scale Attention mechanism(EMA),the efficient Reparameterized Generalized-feature extraction module(CSPStage),the small target detection header,the Repulsion Loss function,and the context aggregation block(CABlock),which are designed to improve the model’s ability to detect targets at multiple scales and the speed of model *** algorithm is validated in detail on two vessel *** comprehensive experimental results demonstrate that,in the infrared dataset,the YOLOv8s algorithm exhibits improvements in various performance ***,compared to the baseline algorithm,there is a 3.1%increase in mean average precision at a threshold of 0.5(mAP(0.5)),a 5.4%increase in recall rate,and a 2.2%increase in mAP(0.5:0.95).Simultaneously,while less than 5 times parameters,the mAP(0.5)and frames per second(FPS)exhibit an increase of 1.7%and more than 3 times,respectively,compared to the CAA_YOLO ***,the evaluation indexes on the visible light data set have shown an average improvement of 4.5%.

关键词： Unmanned ships R_YOLO EMA CSPStage YOLOv8s

Efficient and stable PtFe alloy catalyst for electrocatalytic methanol oxidation with high resistance to CO

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Journal of Energy Chemistry 2024年第3期90卷 327-336,I0008页

作者： Qian Yang Sifan Zhang Fengshun wu Lihua Zhu guang Li Mingzhi Chen An Pei Yingliang Feng Jiangxi Provincial Key Laboratory of Functional Molecular Materials Chemistry College of Chemistry and Chemical EngineeringFaculty of Materials Metallurgy and ChemistryJiangxi University of Science and TechnologyGanzhou 341000JiangxiChina College of Chemistry and Chemical Engineering Xiamen UniversityXiamen 361005FujianChina

Direct methanol fuel cells(DMFC) are widely considered to be an ideal green energy conversion device but their widespread applications are limited by the high price of the Pt-based catalysts and the instability in terms of surface CO toxicity in long-term ***,the PtFe alloy nanoparticles(NPs) with small particle size(~4.12 nm) supported on carbon black catalysts with different Pt/Fe atomic ratios(Pt_(1)Fe_(2)/C,Pt_(3)Fe_(4)/C,Pt_(1)Fe_(1)/C,and Pt_(2)Fe_(1)/C) are successfully prepared for enhanced anti-CO poisoning during methanol oxidation reaction(MOR).The optimal atomic ratio of Pt/Fe for the MOR is 1:2,and the mass activity of Pt_(1)Fe_(2)/C(5.40 A mg_(Pt)^(-1)) is 13.5 times higher than that of conventional commercial Pt/C(Pt/C-JM)(0.40 A mg_(Pt)^(-1)).The introduction of Fe into the Pt lattice forms the PtFe alloy phase,and the electron density of Pt is reduced after forming the PtFe ***-situ Fourier transform infrared results indicate that the addition of oxyphilic metal Fe has reduced the adsorption of reactant molecules on Pt during the *** doping of Fe atoms helps to desorb toxic intermediates and regenerate Pt active sites,promoting the cleavage of C-O bonds with good selectivity of CO_(2)(58.1%).Moreover,the Pt_(1)Fe_(2)/C catalyst exhibits higher CO tolerance,methanol electrooxidation activity,and long-term stability than other Pt_(x)Fe_(y)/C catalysts.

关键词： Alloy catalyst PtFe Methanol oxidation In-situ FTIR CO resistance

Dynamics and data fitting of a time-delayed SIRS hepatitis B model with psychological inhibition factor and limited medical resources

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International Journal of Biomathematics 2024年第2期17卷 263-298页

作者： Ximei Wang Xinzhi ren Yan wu Yong Li School of Information and Mathematics Yangtze University Jingzhou 434023 P.R.China School of Mathematics and Statistics Southwest University Chongqing 400715 P.R.China School of Mathematics and Statistics Lanzhou University Lanzhou 734000 P.R.China

Hepatitis B is an infectious disease worthy of *** the incubation period,psychological inhibition factor,vaccine,limited medical resources and horizontal transmission,an SIRS model is proposed to describe hepatitis B transmission *** order to describe the behavior changes caused by people's psychological changes,the non-monotonic incidence rate is adopted in the *** use the saturated treatment rate to describe the limited medical *** analysis shows the existence conditions of the equilibria,forward or backward bifurcation,Hopf bifurcation and the Bogdanov-Takens *** the observation of the case data of hepatitis B in China,it is found that there are mainly three features,periodic outbreaks,aperiodic outbreaks,and periodic outbreaks turns to aperiodic *** to the above features,we select three different representative regions,Jiangxi,Zhejiang province and Beijing,and then use our model to fit the actual monthly hepatitis B case *** basic reproduction numbers that we estimated are 1.7712,1.4805 and 1.4132,*** results of data fitting are consistent with those of theoretical *** to the sensitivity analysis of Ro,we conclude that reducing contact,increasing treatment rate,strengthening vaccination and revaccinating can effectively prevent and control the prevalence of hepatitis B.

关键词： Hepatitis B SIRS model psychological inhibition factor limited medical resources bifurcation data fitting

Influence of pier height on the safety of trains running on high-speed railway bridges during earthquakes

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Journal of Central South University 2024年第6期31卷 2102-2115页

作者： NIE Yu-tao GUO Wei JIANG Li-zhong YU Zhi-wu ZENG Chen WANG Yang HE Xu-en ren Shao-xun HUANG ren-qiang LIANG guang-yue LI Chang-qing School of Civil Engineering Central South UniversityChangsha 410075China National Engineering Research Center of High-speed Railway Construction Technology Central South UniversityChangsha 410075China

Sudden earthquakes pose a threat to the running safety of trains on high-speed railway bridges,and the stiffness of piers is one of the factors affecting the dynamic response of train-track-bridge *** this paper,a experiment of a train running on a high-speed railway bridge is performed based on a dynamic experiment system,and the corresponding numerical model is *** reliability of the numerical model is verified by ***,the experiment and numerical data are analyzed to reveal the pier height effects on the running safety of trains on *** results show that when the pier height changes,the frequency of the bridge below the 30 m pier height changes greater;the increase of pier height causes the transverse fundamental frequency of the bridge close to that of the train,and the shaking angle and lateral displacement of the train are the largest for bridge with 50 m pier,which increases the risk of derailment;with the pier height increases from 8 m to 50 m,the derailment coefficient obtained by numerical simulations increases by 75% on average,and the spectral intensity obtained by experiments increases by 120% on average,two indicators exhibit logarithmic variation.

关键词： pier height high-speed railway bridge running safety numerical model

Absorption properties and mechanism of lightweight and broadband electromagnetic wave-absorbing porous carbon by the swelling treatment

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International Journal of Minerals,Metallurgy and Materials 2024年第7期31卷 1701-1712页

作者： Jianghao Wen Di Lan Yiqun Wang Lianggui ren Ailing Feng Zirui Jia guanglei wu College of Materials and Chemistry&Chemical Engineering Chengdu University of TechnologyChengdu 610059China School of Materials Science and Engineering Hubei University of Automotive TechnologyShiyan 442002China Institute of Materials for Energy and Environment State Key Laboratory of Bio-fibers and Eco-textilesCollege of Materials Science and EngineeringQingdao UniversityQingdao 266071China Institute of Physics&Optoelectronics Technology Baoji University of Arts and SciencesBaoji 721016China

Bioderived carbon materials have garnered considerable interest in the fields of microwave absorption and shielding due to their reproducibility and environmental *** this study,KOH was evenly distributed on biomass Tremella using the swelling induction method,leading to the preparation of a three-dimensional network-structured hierarchical porous carbon(HPC)through *** achieved microwave absorption intensity is robust at-47.34 dB with a thin thickness of 2.1 ***,the widest effective absorption bandwidth,reaching 7.0 GHz(11–18 GHz),is attained at a matching thickness of 2.2 *** exceptional broadband and reflection loss performance are attributed to the 3D porous networks,interface effects,carbon network defects,and dipole *** has outstanding absorption characteristics due to its excellent impedance matching and high attenuation *** uniform pore structures considerably optimize the impedance-matching performance of the material,while the abundance of interfaces and defects enhances the dielectric loss,thereby improving the attenuation ***,the impact of carbonization temperature and swelling rate on microwave absorption performance was systematically *** research presents a strategy for preparing absorbing materials using biomass-derived HPC,showcasing considerable potential in the field of electromagnetic wave absorption.

关键词： biomass hierarchical porous carbon dielectric loss electromagnetic wave absorption

Experimental investigation on using CO_(2)/H_(2)O emulsion with high water cut in enhanced oil recovery

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Petroleum Science 2024年第2期21卷 974-986页

作者： Xi-Dao wu Peng Xiao Bei Liu guang-Jin Chen Jian-Hua Pang State Key Laboratory of Heavy Oil Processing China University of PetroleumBeijing102249China Ocean Intelligence Technology Center Shenzhen Institute of Guangdong Ocean UniversityShenzhen518120GuangdongChina

CO_(2) emulsions used for EOR have received a lot of interest because of its good performance on CO_(2)mobility ***,most of them have been focusing on the high quality CO_(2) emulsion(high CO_(2) fraction),while CO_(2) emulsion with high water cut has been rarely *** this paper,we carried out a comprehensive experimental study of using high water cut CO_(2)/H_(2)O emulsion for enhancing oil ***,a nonionic surfactant,alkyl glycosides(APG),was selected to stabilize CO_(2)/H_(2)O emulsion,and the corresponding morphology and stability were evaluated with a transparent PVT ***,plugging capacity and apparent viscosity of CO_(2)/H_(2)O emulsion were measured systematically by a sand pack displacement apparatus connected with a 1.95-m long capillary ***,a high water cut(40 vol%) CO_(2)/H_(2)O emulsion was selected for flooding experiments in a long sand pack and a core sample,and the oil recovery,the rate of oil recovery,and the pressure gradients were *** results indicated that APG had a good performance on emulsifying and stabilizing CO_(2) *** inversion from H_(2)O/CO_(2) emulsion to CO_(2)/H_(2)O emulsion with the increase in water cut was ***_(2)/H_(2)O emulsions with lower water cuts presented higher apparent viscosity,while the optimal plugging capacity of CO_(2)/H_(2)O emulsion occurred at a certain water ***,the displacement using CO_(2)/H_(2)O emulsion provided 18.98% and 13.36% additional oil recovery than that using pure CO_(2) in long sand pack and core tests,*** work may provide guidelines for EOR using CO_(2) emulsions with high water cut.

关键词： CO_(2)/H_(2)O emulsion High water cut CO_(2) mobility control Enhanced oil recovery

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

Advances in ice avalanches on the Tibetan Plateau

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Journal of Mountain Science 2024年第6期21卷 1814-1829页

作者： TANG Minggao LI guang ZHAO Huanle XU Qiang wu guangjian YANG Wei GUO Daojing State Key Laboratory of Geohazard Prevention and Geoenvironment Protection Chengdu University of TechnologyChengdu 610059China College of Environment and Civil Engineering Chengdu University of TechnologyChengdu 610059China Institute of Tibetan Plateau Research Chinese Academy of SciencesBeijing 100101China

As some of the greatest natural disasters in the cryosphere,ice avalanches(IAs)seriously threaten lives and cause catastrophic damage to the resource environment,but a comprehensive overview of the state of knowledge on IAs remains *** summarized 63 IAs on the Tibetan Plateau(TP)since the 20th century,of which,over 20 IAs occurred after the 21st *** distributions of IAs are mainly concentrated in the southeastern and northwestern TP,and the occurrence time of IAs is mostly concentrated from July to *** highlight recent advances in mechanical properties and genetic mechanisms of IAs and emphasize that temperature,rainfall,and seismicity are the inducing *** failure modes of IAs are summarized into 6 categories by examples:slip pulling type,slip toppling type,slip breaking type,water level collapse type,cave roof collapse type,and wedge failure ***,we deliver recommendations concerning the risk assessment and prediction of *** results provide important scientific value for addressing climate change and resisting glacier-related hazards.

关键词： Ice avalanche Global warming Genetic mechanism Risk assessment Tibetan Plateau

Porous Ti_(3)C_(2)T_(x) MXene nanosheets sandwiched between polyimide fiber mats for electromagnetic interference shielding

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Nano Research 2024年第3期17卷 2070-2078页

作者： Wenhao Liang Juntao wu Shan Zhang Pei-Yan Zhao Yi Cong Yongqiang Guo guang-Sheng Wang Key Laboratory of Bioinspired Smart Interfacial Science and Technology of Ministry of Education School of ChemistryBeihang UniversityBeijing 100191China

With the rapid development of wireless communication technology and electronic devices,the issue of electromagnetic interference(EMI)is becoming increasingly *** a new and flexible electromagnetic interference shielding material has become a challenging ***,a sandwich-structured EMI shielding composite film was prepared using electrospinning and vacuum filtration *** this process,a porous MXene was synthesized through a reaction with cobalt acetate and served as the intermediate layer in the composite film to shield electromagnetic *** electrospun polyimide(PI)fibers were used as the top and bottom layers of the composite film,which can protect the porous MXene from *** lightweight and flexible composite film integrates electromagnetic interference shielding and thermal insulation capabilities,showing excellent comprehensive *** composite film achieves an EMI shielding effectiveness of 48.8 dB in X-band(8.2–12.4 GHz),and absolute shielding effectiveness of the composite film reached a satisfying 4142.43(dB·cm^(2))/*** to the design of a multi-layer porous structure,the density of the composite film is 0.65 g/***,the thermal conductivity of the film is 0.042 W/(m·K)due to the clamping of electrospun PI fibers,showing excellent thermal insulation ***,the composite film exhibits excellent high and low-temperature *** summary,this work provides a feasible strategy for preparing a lightweight polymer-based EMI shielding film.

关键词： porous MXene polyimide electromagnetic interference shielding thermal insulation