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Gust response of an elasto-flexible morphing wing using fluid–structure interaction simulations

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Chinese Journal of Aeronautics 2024年第2期37卷 45-57页

作者： Jonathan PFLÜGER Christian BREITSAMTER department of mechanical engineering Technical University of MunichGarching 85748Germany

Small and micro unmanned aircraft are the focus of scientific interest due to their wide range of *** often operate in a highly unstable flight environment where the application of new morphing wing technologies offers the opportunity to improve flight *** investigated concept comprises port and starboard adjustable wings,and an adaptive elastoflexible membrane serves as the lifting *** focus is on the benefits of the deforming membrane during the impact of a one-minus-cosine type *** a low Reynolds number of Re=264000,the morphing wing model is investigated numerically by unsteady fluid-structure interaction ***,the numerical results are validated by experimental data from force and moment,flow field,and deformation ***,with the rigid wing as the baseline,the flexible case is investigated,focusing on the advantages of the elastic *** all configurations studied,the maximum amplitude of the lift coefficient under gust load shows good agreement between the experimental and numerical *** the decay of the gust,they differ more the higher the aspect ratio of the *** considering the flow field,the main differences are due to the separation behavior on the upper side of the *** flow reattaches earlier in the experiments than in the simulations,which explains the higher lift values observed in the *** at one intermediate configuration does the lift amplitude of the rigid configuration exceeds that of the flexible by about 12%,with the elastic membrane resulting in a smaller and more uniform peak load,which is also evident in the wing loading and hence in the root bending moment.

关键词： Membrane wing Morphing wing Flexible wing surface Computational fluid dynam-ics Fluid-structure interaction Unsteady inflow condition Gust response

Synthesis and Thermal Characterization of Solar Salt-Based Phase Change Composites with Graphene Nanoplatelets

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Journal of Thermal Science 2024年第2期33卷 491-500页

作者： Pethurajan VIGNESHWARAN Saboor SHAIK Sivan SURESH Müslüm ARICI Asif AFZAL department of Thermal and Energy engineering School of Mechanical Engineering(SMEC)Vellore Institute of TechnologyVelloreTamil NaduIndia Nanotechnology Research Laboratory Department of Mechanical EngineeringNational Institute of TechnologyTiruchirappalliTamil NaduIndia mechanical engineering department Engineering FacultyKocaeli UniversityUmuttepe CampusKocaeli41001Turkey department of mechanical engineering P.A.College of Engineering(affiliated to Visvesvaraya Technological UniversityBelagavi)Mangaluru574153India

Thermal energy storage(TES) systems use solar energy despite its irregular availability and day-night temperature *** work reports the thermal characterizations of solar salt-based phase change composites in the presence of graphene nanoplatelets(GNP).Solar salt(60:40 of NaNO_(3):KNO_(3)) possessing phase transition temperature and melting enthalpy of 221.01℃ and 134.58 kJ/kg is proposed as a phase change material(PCM) for high-temperature solar-based energy storage *** conductivity must be improved to make them suitable for widespread applications and to close the gap between the system needs where they are *** is added at weight concentrations of 0.1%,0.3%,and 0.5% with solar salt using the ball milling method to boost its thermal *** studies indicated the formation of a uniform surface of GNP on solar *** spectrum peaks identified the physical interaction between salt and *** characterization of the composites,such as thermal conductivity,DSC and TGA was carried out for the samples earlier and later 300 thermal cycles.0.5% of GNP has improved the thermal conductivity of salt by 129.67% and after thermal cycling,the enhancement reduced to 125.21% indicating that thermal cycling has a minor impact on thermal *** change temperature decreased by around 2.32% in the presence of0.5% GNP and the latent heat reduced by 4.34% after thermal *** thermograms depicted the composites initiated the weight loss at around 550℃ after which it was *** thermal cycling,the weight loss initiated at ~40℃ lower compared to pure salt,which was found to be a minor *** characterization of solar salt and GNP-based solar salt composites revealed that the composites can be used for enhanced heat transfer in high-temperature solar-based heat transfer and energy storage applications.

关键词： thermal energy storage high temperature solar salt graphene nanoplatelets thermal characterization

A path planning algorithm for a crop monitoring fixed-wing unmanned aerial system

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Science China(Information Sciences) 2024年第08期67卷 5-23页

作者： Longhao QIAN Yi Lok LO Hugh Hong-tao LIU Institute of Aerospace Studies University of Toronto department of mechanical engineering The University of Hong Kong

With the growing demand for automation in agriculture, industries increasingly rely on drones to perform crop monitoring and surveillance. In this regard, fixed-wing unmanned aerial systems(UASs)are viable platforms for scanning a large crop field, given their payload capacity and range. To achieve maximum coverage without landing for battery replacement, an algorithm for producing a minimal required energy survey path is essential. Hence, an energy-aware coverage path planning algorithm is proposed *** constraints for a fixed-wing UAS to fly at low altitudes while achieving full coverage of the crop field are first analyzed. Then, the full path is decomposed into straight-line and U-turn primitives. Finally, an algorithm to calculate a combination of straight-line segments and U-turns is proposed to obtain the path with minimum required energy consumption. The genetic algorithm is used to efficiently determine the order of the straight-line paths to traverse. Case studies show that the proposed algorithm can produce planning results for a convex-polygon-shaped crop field.

关键词： aerial survey energy minimization fixed-wing UAS genetic algorithm path planning

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Omni-functional simultaneous interfacial treatment for enhancing stability and outgassing suppression of lithium-ion batteries

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Journal of Energy Chemistry 2024年第7期94卷 677-687页

作者： Youbean Lee Chanjoo Park Kyoungmin Min Kwangjin Park department of mechanical engineering Gachon UniversityGyeonggi-do 13120Republic of Korea department of Battery engineering Gachon UniversityGyeonggi-do 13120Republic of Korea School of mechanical engineering Soongsil UniversitySeoul 06978Republic of Korea

Ni-rich layered oxides in lithium-ion batteries have problems with gas generation and electrochemical performance reduction due to residual lithium's reaction on the surface with the *** address this issue,in this study,the Acid solvent evaporation(AsE)method has been proposed as a potential method to remove residual lithium while promoting the formation of a new LiNO_(3)-derived coating layer on the cathode *** reduction of residual lithium using the ASE method and the construction of a LiNO_(3)-derived coating layer suppresses gas evolution caused by the side effects of the electrolyte,improves electrochemical performance,and improves thermal stability by facilitating the smooth movement of lithium ***,the structural stability and resistance change due to the LiNO_(3)-derived coating layer effects is guaranteed through cycling and DCIR of the pouch *** a result,compared to Pristine,the capacity retention of coin cells increased by 8%after 100 cycles,and pouch cells increased by 25%after 160 *** addition,after cycling the pouch cell,CO_(2) gas has significantly reduced by about 30%compared to Pristine using gas *** ASE method effectively forms a robust LiNO_(3)-derived coating layer on the cathode active material,which helps minimize electrolyte reactivity,suppress ,CO_(2) emissions,enhance surface structure stability,improve thermal stability,and improveoverallbatteryperformance.

关键词： Lithium-ion batteries Ni-rich NCM Acid solvent evaporation LiNO_(3)-derived coating Gasevolution

Battery pack capacity estimation for electric vehicles based on enhanced machine learning and field data

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Journal of Energy Chemistry 2024年第5期92卷 605-618页

作者： Qingguang Qi Wenxue Liu Zhongwei Deng Jinwen Li Ziyou Song Xiaosong Hu College of mechanical and Vehicle engineering Chongqing UniversityChongqing 400044China School of mechanical and Electrical engineering University of Electronic Science and Technology of ChinaChengdu 611731SichuanChina department of mechanical engineering National University of SingaporeSingapore 117575Singapore

Accurate capacity estimation is of great importance for the reliable state monitoring,timely maintenance,and second-life utilization of lithium-ion *** numerous works on battery capacity estimation using laboratory datasets,most of them are applied to battery cells and lack satisfactory fidelity when extended to real-world electric vehicle(EV)battery *** challenges intensify for large-sized EV battery packs,where unpredictable operating profiles and low-quality data acquisition hinder precise capacity *** fill the gap,this study introduces a novel data-driven battery pack capacity estimation method grounded in field *** proposed approach begins by determining labeled capacity through an innovative combination of the inverse ampere-hour integral,open circuit voltage-based,and resistance-based correction ***,multiple health features are extracted from incremental capacity curves,voltage curves,equivalent circuit model parameters,and operating temperature to thoroughly characterize battery aging behavior.A feature selection procedure is performed to determine the optimal feature set based on the Pearson correlation ***,a convolutional neural network and bidirectional gated recurrent unit,enhanced by an attention mechanism,are employed to estimate the battery pack capacity in real-world EV ***,the proposed method is validated with a field dataset from two EVs,covering approximately 35,000 *** results demonstrate that the proposed method exhibits better estimation performance with an error of less than 1.1%compared to existing *** work shows great potential for accurate large-sized EV battery pack capacity estimation based on field data,which provides significant insights into reliable labeled capacity calculation,effective features extraction,and machine learning-enabled health diagnosis.

关键词： Electricvehicle Lithium-ion battery pack Capacity estimation Machine learning Field data

A shield of defense:Developing ballistic composite panels with effective electromagnetic interference shielding absorption

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Defence Technology（防务技术） 2024年第5期35卷 123-136页

作者： Nisrin Rizek Abdelal mechanical engineering department Jordan University of Science and TechnologyIrbid 22110Jordan

The primary goal of this study is to develop cost-effective shield materials that offer effective protection against high-velocity ballistic impact and electromagnetic interference(EMI)shielding capabilities through *** fiber-reinforced epoxy composite panels,each with a different fabric material and stacking sequence,have been fabricated using a hand-layup vacuum bagging *** panels made of Kevlar and glass fibers,referred to as(K-NIJ)and(G-NIJ),have been tested according to the National Institute of Justice ballistic resistance protective materials test NIJ 0108.01 Standard-Level IIIA(9 mm×19 mm FMJ 124 g)*** panels,namely,a hybrid of Kevlar and glass(H-S),glass with ceramic particles(C-S),and glass with recycled rubber(R-S)have been impacted by the bullet at the center,while the fourth panel made of glass fiber(G-S)has been impacted at the *** shielding properties have been measured in the X-band frequency range via the reflection-transmission *** indicate that four panels(K-NIJ,G-NIJ,H-S,and G-S)are capable of withstanding high-velocity impact by stopping the bullet from penetrating through the panels while maintaining their structural ***,under such conditions,these panels may experience localized delamination with variable *** EMI measurements reveal that the highest absorptivity observed is 88% for the KNIJ panel at 10.8 GHz,while all panels maintain an average absorptivity above 65%.All panels act as a lossy medium with a peak absorptivity at different frequencies,with K-NIJ and H-S panels demonstrating the highest *** summary,the study results in the development of a novel,costeffective,multifunctional glass fiber epoxy composite that combines ballistic and electromagnetic interference shielding *** material has been developed using a simple manufacturing method and exhibits remarkable ballistic protection that outperforms Kevlar in terms of shielding efficiency;no bullet

关键词： Ballistic FRP composite EMI shielding Absorptivity CT-Scan NIJ test Bullet Defense

Assessment of scale interactions associated with wake meandering using bispectral analysis methodologies

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Theoretical & Applied Mechanics Letters 2024年第2期14卷 65-75页

作者： Dinesh Kumar Kinjangi Daniel Foti department of mechanical engineering University of MemphisMemphisTennesseeUSA

Large atmospheric boundary layer fluctuations and smaller turbine-scale vorticity dynamics are separately hypothesized to initiate the wind turbine wake meandering phenomenon,a coherent,dynamic,turbine-scale oscillation of the far *** interactions,the mechanism of energy transfers between scales,manifest as triples of wavenumbers or frequencies and can be characterized through bispectral *** bispectrum,which correlates the two frequencies to their sum,is calculated by two recently developed multi-dimensional modal decomposition methods:scale-specific energy transfer method and bispectral mode ***-eddy simulation of a utility-scale wind turbine in an atmospheric boundary layer with a broad range of large length-scales is used to acquire instantaneous velocity *** bispectrum from both methods identifies prominent upwind and wake meandering interactions that create a broad range of energy scales including the wake meandering *** coherent kinetic energy associated with the interactions shows strong correlation between upwind scales and wake meandering.

关键词： Wind turbine wake Mode decomposition Bispectral analysis

Experimental Study on Heat Storage Properties Comparison of Paraffin/Metal Foams Phase Change Material Composites

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Journal of Thermal Science 2024年第2期33卷 469-478页

作者： Waqar AHMED Abid HUSSAIN Hanzla SHAHID Imran ALI Hafiz Muhammad ALI department of mechanical engineering University of Engineering and TechnologyTaxila47080Pakistan department of mechanical engineering Institute of Space TechnologyIslamabadPakistan department of mechanical Mechatronics and Manufacturing EngineeringUniversity of Engineering and Technology LahoreFaisalabad CampusPunjabPakistan mechanical engineering department King Fahd University of Petroleum and MineralsDhahran31261Saudi Arabia Interdisciplinary Research Center for Renewable Energy and Power Systems(IRC-REPS) King Fahd University of Petroleum and MineralsDhahran31261Saudi Arabia

Heat storage properties of phase change materials(PCMs) are essential characteristics that perform a key role in thermal heat energy storage *** thermal properties of PCMs can be improved by developing metal foam/PCM *** addition of metal foam in PCMs has a significant effect on the thermal characteristics of *** this paper,the heat storage properties of two different metal foam/PCM composites were experimentally *** behavior of paraffin in metal foam(copper and iron-nickel)/paraffin composites concerning pure paraffin at a constant heat flux of 1000 W/m^(2) in three directions simultaneously(x,y,and z) was *** was infiltrated into copper and iron-nickel foams to develop composite materials which resulted in enhancing the thermal conductivity of the paraffin.A comparative analysis is made on the heat storage properties of paraffin in copper and iron-nickel foams/paraffin *** temperature distribution during the phase transition process is experimentally *** comparison indicates that temperature uniformity in copper foam/paraffin composite is better than in iron-nickel foam/paraffin composite and pure paraffin at the same heat *** results show that at heat flux of 1000 W/m^(2),the heat storage time for copper foam/paraffin composite is 20.63% of that of iron-nickel foam/paraffin composite.

关键词： heat storage capacity paraffin/metal foam composite temperature uniformity heat storage rate phase transition process

Investigation on the Velocity-Dependent Adhesion Hysteresis via Molecular Dynamics Simulation

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Acta Mechanica Solida Sinica 2024年第3期37卷 423-429页

作者： Jinshan He Yiran Li Zhaoyang Ma Ganyun Huang department of Mechanics School of Mechanical EngineeringTianjin UniversityTianjin300350China

Adhesion plays an important role in miniaturized devices and technologies,which depends not only on indentation depth but also on the history of contact making and breaking,giving rise to adhesion *** the present work,adhesion hysteresis has been investigated via molecular dynamics simulations on approaching and retracting a rigid tip to and from a *** results show that hysteresis in the force-displacement curve that depends on approaching and retraction velocities arises under both elastic and plastic *** underlying mechanisms have been *** implications of the results in friction have been discussed briefly.

关键词： Adhesion hysteresis Molecular dynamics simulation Contact instability Plastic deformation