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

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

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Dynamically updated digital twin for prognostics and health management:Application in permanent magnet synchronous motor

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Chinese Journal of Aeronautics 2024年第6期37卷 244-261页

作者： Haoyu GUO Shaoping WANG Jian SHI Tengfei MA Giorgio GUGLIERI Rujun JIA Fausto LIZZIO School of Automation Science and Electrical engineering Beihang UniversityBeijing 100191China Tianmushan Laboratory Hangzhou 310023China department of mechanical and aerospace engineering Polytechnic University of TurinTurin 10129Italy Beihang Ningbo Research Institute Ningbo 315800China

Current research on Digital Twin(DT)based Prognostics and Health Management(PHM)focuses on establishment of DT through integration of real-time data from various sources to facilitate comprehensive product monitoring and health ***,there still exist gaps in the seamless integration of DT and PHM,as well as in the development of DT multi-field coupling modeling and its dynamic update *** the product experiences long-period degradation under load spectrum,it is challenging to describe the dynamic evolution of the health status and degradation progression *** addition,DT update algorithms are difficult to be integrated simultaneously by current *** paper proposes an innovative dual loop DT based PHM framework,in which the first loop establishes the basic dynamic DT with multi-filed coupling,and the second loop implements the PHM and the abnormal detection to provide the interaction between the dual loops through updating *** proposed method pays attention to the internal state changes with degradation and interactive mapping with dynamic parameter ***,the Independence Principle for the abnormal detection is proposed to refine the theory of *** at the first loop focus on accurate modeling of multi-field coupling,while the events at the second loop focus on real-time occurrence of anomalies and the product degradation *** interaction and collaboration between different loop models are also ***,the Permanent Magnet Synchronous Motor(PMSM)is used to verify the proposed *** results show that the modeling method proposed can accurately track the lifecycle performance changes of the entity and carry out remaining life prediction and health management effectively.

关键词： Digital Twin(DT) Dynamic Update Independence Principle Multi-field Coupling Permanent Magnet Synchronous Motor(PMSM) Prognostics and Health Management(PHM)

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Efficient processed carbon Soot@MoS2 hybrid Bi-functional electrode for dye-sensitized solar cell and asymmetric supercapacitor devices

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Nano Materials Science 2024年第4期6卷 484-494页

作者： B.Arjun Kumar Gopal Ramalingam Salah Addin Burhan Al Omari Zhumabay Bakenov Sambasivam Sangaraju Sangarapani Sudhakar Quantum Material Research Lab (QMRL) Department of Nanoscience and TechnologyAlagappa University department of mechanical and aerospace engineering United Arab Emirates University department of Chemical and Materials engineering Nazarbayev University National Water and Energy Center United Arab Emirates University department of Physics Alagappa University

A feasible approach to rectify the world's energy demand using sustainable development of adequate energy generation and storage technologies in a single *** this respect,we made a holistic approach with a bifunctional electrode material to perform effectively in energy generation and storage ***2nanosheets were produced by the eco-friendly method and reduced graphene oxide is used to prepared by carbon soot which is derived from castor *** prepared soot and rGO were combined with MoS2nanosheets using a simple sonication *** as-prepared sample was introduced in the supercapacitor and DSSC *** combination MoS2@rGO provides an enhanced conversion efficiency of 11.81%and the reproducibility of DSSC is also ***,MoS2@rGO is used to fabricate an asymmetric supercapacitor to investigate its real-time *** device produced the maximum power density （1666.6 mW/kg） and energy density （25.69 mWh/Kg） at 1 A/*** asymmetric supercapacitor device holds a cyclic stability of 81.4%for 5000 cycles and it powered up an LED device for 4 min.

关键词： Carbon soot Solar cells Supercapacitors MoS 2 DSSC

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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

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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

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Lap-Shear Performance of Weld-Bonded Mg Alloy and Austenitic Stainless Steel in Three-Sheet Stack-Up

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Chinese Journal of mechanical engineering 2024年第4期37卷 342-353页

作者： Sunusi Marwana Manladan Mukhtar Fatihu Hamza Singh Ramesh Zhen Luo School of Materials Science and engineering Tianjin UniversityTianjin 300350China department of mechanical engineering Faculty of EngineeringBayero UniversityKano 3011Nigeria department of mechanical engineering College of EngineeringPrince Sattam bin Abdulaziz University11942 AlkharjSaudi Arabia department of mechanical engineering Faculty of EngineeringUniversity of Malaya50603 Kuala LumpurMalaysia

With the growing interest in utilizing Mg and austenitic stainless steel(ASS)in the automotive sector,joining them together in three-sheet configuration is ***,achieving this task presents considerable challenges due to the large differences in their physical,metallurgical and mechanical *** overcome these challenges,the feasibility of using weld-bonding to join Mg alloy/ASS/ASS was *** nugget formation,interface characteristics,microstructure and mechanical properties of the joints were *** results show that the connection between the Mg alloy and upper ASS was achieved through the combined effect of the cured adhesive and weld-brazing in the weld *** the other hand,a metallurgical bond was formed at the ASS/ASS *** Mg nugget microstructure exhibited fine columar grains composed predominantly of primaryα-Mg grains along with a eutectic mixture ofα-Mg andβ-*** nugget formed at the ASS/ASS interface consisted largely of columnar grains of austenite,with some equiaxed dendritic grains formed at the centerline of the *** weld-bonded joints exhibited an average peak load and energy absorption of about 8.5 kN and 17 J,respectively(the conventional RSW joints failed with minimal or no load application).The failure mode of the joints changed with increasing welding current from interfacial failure via the Mg nugget/upper ASS interface to partial interfacial failure(part of the Mg nugget was pulled out of the Mg sheet).Both failure modes were accompanied by cohesive failure in the adhesive zone.

关键词： Weld-bonding Resistance spot welding Austenitic stainless steel Mg alloy Failure mode

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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

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Gravity-driven powder flow and the influence of external vibration on flow characteristics

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Particuology 2024年第5期88卷 201-209页

作者： Muhammad Shahid Ansari Ratna Kumar Annabattula Sathyan Subbiah department of mechanical engineering Indian Institute of Technology MadrasChennai 600036India

The controlled and homogeneous flow of dry granular powders through hoppers is essential for applications,namely,packaging of food grains,fertilizers and additive manufacturing processes such as directed energy deposition for better product *** of the major issues encountered in the granular flows through hoppers is flow stagnation due to the well-known arching ***-assisted granular flow through hoppers is one of the mechanisms used for better mass flow *** this work,the influence of external mechanical vibration on the powder flow is investigated experimentally and using discrete element ***,the mass flow rate through the hopper increases with an increase in vibration amplitude and then decreases,signifying the existence of an optimal amplitude of *** DEM simulations explained the underlying mechanisms for the existence of an optimal amplitude of vibration corresponding to the maximum mass flow rate.A range of vibration amplitudes from 0 mm to 3.5 mm is used to study the flow behaviour;the maximum flow of around 33 g/s to 35 g/s is observed for 0.75 mm to 1.25 mm vibration amplitude for the hopper-particle combination studied in this *** work also reports the influence of vibration frequency,hopper,and particle dimension on the flow *** research facilitates the effective use of mechanical vibration to enhance powder flow that can further be extended to non-spherical and multi-material particles.

关键词： Discrete element method Flow rate Granular flow Path tracking Vibration intensity

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Investigations on High-Speed Flash Boiling Atomization of Fuel Based on Numerical Simulations

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Computer Modeling in engineering & Sciences 2024年第5期139卷 1427-1453页

作者： Wei Zhong Zhenfang Xin Lihua Wang Haiping Liu School of aerospace engineering and Applied Mechanics Tongji UniversityShanghai200092China Beijing mechanical Equipment Research Institute Beijing100854China

Flash boiling atomization(FBA)is a promising approach for enhancing spray atomization,which can generate a fine and more evenly distributed spray by increasing the fuel injection temperature or reducing the ambient ***,when the outlet speed of the nozzle exceeds 400 m/s,investigating high-speed flash boiling atomization(HFBA)becomes quite *** difficulty arises fromthe involvement ofmany complex physical processes and the requirement for a very fine mesh in numerical *** this study,an HFBA model for gasoline direct injection(GDI)is *** model incorporates primary and secondary atomization,as well as vaporization and boilingmodels,to describe the development process of the flash boiling *** to lowspeed FBA,these physical processes significantly impact *** this model,the Eulerian description is utilized for modeling the gas,and the Lagrangian description is applied to model the droplets,which effectively captures the movement of the droplets and avoids excessive mesh in the Eulerian *** various conditions,numerical solutions of the Sauter mean diameter(SMD)for GDI show good agreement with experimental data,validating the proposed model’s *** based on this HFBA model investigate the influences of fuel injection temperature and ambient pressure on the atomization *** analyses of the velocity field,temperature field,vapor mass fraction distribution,particle size distribution,and spray penetration length under different superheat degrees reveal that high injection temperature or low ambient pressure significantly affects the formation of small and dispersed droplet *** effect is conducive to the refinement of spray particles and enhances atomization.

关键词： High-speed flash boiling atomization numerical simulations Eulerian description Lagrangian description gasoline direct injection

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Multi-blade rubbing characteristics of the shaft-disk-blade-casing system with large rotation

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Applied Mathematics and Mechanics(English Edition) 2024年第1期45卷 111-136页

作者： Zhiyuan WU Linchuan ZHAO Han YAN Ge YAN Ao CHEN Wenming ZHANG State Key Laboratory of mechanical System and Vibration Shanghai Jiao Tong UniversityShanghai 200240China Shanghai Institute of aerospace Systems engineering Shanghai 201108China

Blade rubbing faults cause detrimental impact on the operation of aeroengines. Most of the existing studies on blade rubbing in the shaft-disk-blade-casing(SDBC) system have overlooked the elastic deformation of the blade, while some only consider the whirl of the rotor, neglecting its spin. To address these limitations, this paper proposes a dynamic model with large rotation for the SDBC system. The model incorporates the spin and whirl of the rotor, enabling the realistic reproduction of multiblade rubbing faults. To verify the accuracy of the SDBC model with large rotation and demonstrate its capability to effectively consider the rotational effects such as the centrifugal stiffening and gyroscopic effects, the natural characteristics and dynamic responses of the proposed model are compared with those obtained from reported research and experimental results. Furthermore, the effects of the rotating speed, contact stiffness,and blade number on the dynamic characteristics of the SDBC system with multi-blade rubbing are investigated. The results indicate that the phase angle between the rotor deflection and the unbalance excitation force increases with the increasing rotating speed,which significantly influences the rubbing penetration of each blade. The natural frequency of the SDBC system with rubbing constrain can be observed in the acceleration response of the casing and the torsional response of the shaft, and the frequency is related to the contact stiffness. Moreover, the vibration amplitude increases significantly with the product of the blade number under rubbing, and the rotating frequency approaches the natural frequency of the SDBC system. The proposed model can provide valuable insight for the fault diagnosis of rubbing in bladed rotating machinery.

关键词： shaft-disk-blade-casing(SDBC) large rotation spin and whirl multi-blade rubbing rotational effect

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