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Stability-derived bounds on the realizable acoustic properties of active metamaterials

Physical Review Applied 2024年第5期21卷 L051002-L051002页

作者： Dylan A. Kovacevich Karl Grosh Bogdan-Ioan Popa Department of Mechanical Engineering Department of Biomedical Engineering

Active acoustic metamaterials consisting of sensor and driver elements that produce a programmed response to impinging acoustic waves have been widely considered an appealing way to overcome the fundamental shortcomings of passive structures. However, research into active metamaterials has been hindered by their potential instability resulting from very complex interactions between cells and the lack of realistic stability models taking these interactions into account. We present a general method for assessing the stability of active metamaterials of arbitrary geometry and number of cells and show that stability imposes previously unknown limitations on the realizable acoustic properties. We validate the theory by accurately predicting the bounds on the realizable effective properties of an experimental metamaterial.

关键词： Acoustic measurements Acoustic signal processing & noise Acoustic wave phenomena Acoustic metamaterials Smart materials

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Sedimentation-driven one-step fabrication of bifunctional single-layered triboelectric nanogenerator from sol-state composite precursor

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Friction 2025年第2期13卷 49-56页

作者： Yoonsang Ra Dongik Kam Sunmin Jang Sumin Cho Donghan Lee Dongwhi Choi Department of Mechanical Engineering(Integrated Engineering Program) Kyung Hee UniversityGyeonggi 17104Republic of Korea

Although the triboelectric nanogenerator(TENG)has been highlighted as a promising mechanical energy harvester,the requirement of stacking the two individual layers,contact and conductive layers,has been ball and chain around the ankle of unleashing potential and an advantage of TENGs in their application expansion and ***,one-step fabrication of a single-layered bifunctional composite film-based TENG(BFTENG)driven by the sedimentation of a sol-state precursor is proposed for the extremely facile conversion of various ordinary items into energy *** BF-TENG consists of the polydimethylsiloxane(PDMS)matrix and a carbon nanopowder filler,and it includes both the dielectric part(DP)and conductive part(CP)in one single *** electrical percolation threshold of the incorporated concentration of carbon,ICC,for CP to act as a passage through which induced charges move in BF-TENGs is determined to be 1.0 wt%.The degree of carbon sedimentation in developing the proposed composite can be controlled by the curing speed and the probability of a crosslinking *** maximum peak power is approximately 0.093μW when the contact surface area is 78.5 mm2;the contact frequency is 8 Hz,and the connected load resistance is 9 MΩ.Based on these results,the electrical performance of BF-TENGs in response to various physical stimuli is characterized considering the mechanical energy sources available in daily ***,converting ordinary surfaces such as desks and human skin into BF-TENGs through a single coating procedure and harvesting energy to power an electric device are demonstrated as a proof-of-concept.

关键词： triboelectric nanogenerator one-step fabrication sedimentation bifunctional composite film

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Studying the Impact of T4 and T6 Heat Treatments on Corrosion and mechanical Properties of 6082-Al Alloy Treated with Al-5Ti-1B Grain Refiner

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Journal of Bio- and Tribo-Corrosion 2025年第1期11卷 1-13页

作者： Abd El-Aziz, Kh. Saber, D. Materials Engineering Department Faculty of Engineering Zagazig University Zagazig44519 Egypt Mechanical Engineering Department College of Engineering Taif University Taif Saudi Arabia Industrial Engineering Program Mechanical Engineering Department College of Engineering Taif University Taif Saudi Arabia

The mechanical and corrosion characteristics of aluminum alloys can be influenced not only by the addition of grain refiners but also by heat treatment that modifies the microstructure and introduces variations in these characteristics. The purpose of this work was to examine how the mechanical properties and corrosion resistance of 6082-Al alloy with Al-5Ti-1B grain refiner are affected by both artificial and natural aging heat treatments. By using the permanent mold casting process, the required specimens of the investigated alloys were produced. A VHS-1000 microhardness testing apparatus is used to measure microhardness at a 100 g load. A sliding wear test is carried out using a pin-on-disk apparatus. Potentiodynamic polarization curves in a 3.5 weight percent NaCl solution are used to assess the corrosion behavior of every specimen. The current results revealed that the mechanical properties improved markedly with the additions of Al–5Ti-1B grain refiner to the investigated alloy, this is maybe due to the microstructure changes as a result of grain refiner additions. Although the addition of Al-5Ti-1B grain refiner to 6082-Al alloy improved the hardness and wear resistance, it showed a negative influence on the corrosion resistance of these alloys. The results also demonstrated that, when compared to as-cast condition, artificial heat treatment of 6082-Al alloy inoculated by Al-5Ti-1B grain refiner improved their hardness, wear resistance, and corrosion properties significantly. Furthermore, compared to natural aging heat treatment, artificial aging heat treatment demonstrated a noticeably improved level of hardness, wear, and corrosion behavior. © The Author(s), under exclusive licence to Springer Nature Switzerland AG 2025.

关键词： Aluminum corrosion

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Toward smart manufacturing systems incorporating reconfiguration issues

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International Journal of Industrial and Systems engineering 2024年第1期46卷 1-33页

作者： Garbie, Ibrahim H. Garbie, Abdelrahman I. Department of Mechanical Engineering-Industrial Engineering Program College of Engineering at Helwan Helwan University Cairo Egypt Department of Mechanical Engineering University of Louisiana at Lafayette LafayetteLA United States

Nowadays, Industry 4.0 will become urgently implemented in most developed countries, although it is still mainly conceptual. As there are three different aspects making up Industry 4.0 (I4.0), such as digital systems, biological systems, and physical systems, most of the research published works were focused on mainly the first one. The smart manufacturing system (SMS) is not an invention, although it is representing the heart of I4.0. The SMS is a rebirth of a new version and innovation of production systems taken into consideration reconfiguring the existing manufacturing systems through adding machines with sensors, actuators, and control architectures for achieving the ultimate goals of I4.0. There are many challenges when reconfiguring these systems as an essential requirement to implement I4.0, representing the degree of individual system complexity, reconfigurable machines, material handling systems, system layout, competitive manufacturing strategies, leanness agility, and embedded systems (cyber-physical systems). In this paper, a new perspective of reconfiguring manufacturing systems will be figured out, and the reconfigurability level toward I4.0 will be presented. © 2024 Inderscience Enterprises Ltd.

关键词： Industry 4.0

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Comparison of Tribological Behavior of Hard Faced Fe-Based Metallic Composite Coatings Sprayed Using HVOF

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Journal of Bio- and Tribo-Corrosion 2025年第1期11卷 1-18页

作者： Soni, Piyush Kumar Prasad, C. Durga Manjunath, H.R. Tiwari, Amit Raju, Vadali Pitchi Athithan, Senthil Deshmukh, Khemraj Kumar, Anjani Department of Mechanical Engineering New Horizon College of Engineering Karnataka Bengaluru India Department of Mechanical Engineering RV Institute of Technology and Management Karnataka Bengaluru India Department of Mechanical Engineering Ramaiah Institute of Technology Karnataka Bengaluru560054 India Department of Mechanical Engineering Suresh Gyan Vihar University Jaipur India Mechanical Engineering Department & amp Principal Indur Institute of Engineering and Technology Siddipet India Department of Computer Science and Engineering Koneru Lakshmaiah Education Foundation Andhra Pradesh Vaddeswaram India Department of Biomedical Engineering Parul University Gujarat Vadodara India Mechanical Engineering Department Government Engineering College Arwal India

Fe-based alloys have recently become well-known for their ability to resist wear and corrosion. Iron, the primary component of alloys, is a cheaper option than alloys made from Co and Ni. There is a need for affordable and easily obtainable coatings based on iron. Coatings in the Fe–Ni–Cr system have demonstrated superior wear resistance compared to other commonly used Fe-based metallic coatings. The Fe-12Ni17Cr2.5Mo2.3Si0.03C based (Metco 41C) metallic coatings were applied onto boiler steel substrates using the High Velocity Oxy-Fuel (HVOF) spraying method. The coatings were examined using X-ray diffraction (XRD), a scanning electron microscope (SEM), and a microhardness tester to determine their density, porosity, microstructure, hardness, and surface roughness. The sliding wear behavior of the substrate and coatings was studied using the pin-on-disk tribometer. Figuring out the wear loss and coefficient of friction. Comparison was made of wear results between the substrate, coatings, and composite coatings. By combining these carbide powders with 30% SiC and WC-12Co particles, the coating’s wear resistance is enhanced in comparison to the Metco 41C coating. In comparison to boiler steel, the Metco 41C + SiC and Metco 41C + WC–Co coatings exhibited a roughly 70% and 40% reduction in volume loss compared with boiler steel respectively. © The Author(s), under exclusive licence to Springer Nature Switzerland AG 2024.

关键词： HVOF thermal spraying

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Influence of Biomimetic Apatite Coating on the Biobehavior of TiO_(2)Scaffolds

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Journal of Bionic engineering 2024年第4期21卷 1975-1986页

作者： Shima Mahtabian Seyed Mehdi Mirhadi Nahid Hassanzadeh Nemati Melika Sharifi Fariborz Tavangarian Department of Biomedical Engineering University of DelawareNewarkDE19716USA Department of Ceramic Engineering Islamic Azad University(Shahreza Branch)ShahrezaIsfahan86145-311Iran Department of Biomedical Engineering Islamic Azad University(Science and Research Branch)TehranIran Mechanical Engineering Program School of ScienceEngineering and TechnologyPennsylvania State UniversityHarrisburgMiddletownPA17057USA Department of Materials Science&Engineering Islamic Azad University(Najaf Abad Branch)Najaf AbadIsfahan***Iran Biomedical Engineering Department Pennsylvania State UniversityState CollegeUniversity ParkPennsylvania16802USA

Immersion of scaffolds in Simulated Body Fluid(10SBF)is a standardized method for evaluating their bioactivity,simulating in vivo conditions where apatite deposits can be formed on the surface of scaffold,facilitating bone integration and ensuring their suitability for bone implant purposes,ultimately contributing to long-term implant *** effect of apatite deposition on bioactivity and cell behavior of TiO_(2)scaffolds was *** were soaked in 10SBF for different durations to form HAP layer on their *** results proved the development of a hydroxyapatite film resembling the mineral composition of bone Extracellular Matrix(ECM)on the TiO_(2)*** XRD test findings showed the presence of hydroxyapatite layer similar to bone at the depth of 10 nm.A decrease in the specific surface area(18.913 m^(2)g^(−1)),the total pore volume(0.045172 cm^(3)g^(−1)(at p/p0=0.990)),and the mean pore diameter(9.5537 nm),were observed by BET analysis which confirmed the formation of the apatite *** was found that titania scaffolds with HAP coating promoted human osteosarcoma bone cell(MG63)cell attachment and *** seems that immersing the scaffolds in 10SBF to form HAP coating before utilizing them for bone tissue engineering applications might be a good strategy to promote bioactivity,cell attachment,and implant fixation.

关键词： Titania Hierarchical meso/macro porous 10SBF Biomimetic apatite Coating

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A reinforcement learning approach to vehicle coordination for structured advanced air mobility

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Green Energy and Intelligent Transportation 2024年第2期3卷 20-37页

作者： Sabrullah Deniz Yufei Wu Yang Shi Zhenbo Wang Department of Mechanical Aerospaceand Biomedical EngineeringThe University of TennesseeKnoxvilleTN37996USA

Advanced Air Mobility(AAM)has emerged as a pioneering concept designed to optimize the efficacy and ecological sustainability of air *** core objective is to provide highly automated air transportation services for passengers or cargo,operating at low altitudes within urban,suburban,and rural *** seeks to enhance the efficiency and environmental viability of the aviation sector by revolutionizing the way air travel is *** a complex aviation environment,traffic management and control are essential technologies for safe and effective AAM *** of the most difficult obstacles in the envisioned AAM systems is vehicle coordination at merging points and *** escalating demand for air mobility services,particularly within urban areas,poses significant complexities to the execution of such *** this study,we propose a novel multi-agent reinforcement learning(MARL)approach to efficiently manage high-density AAM operations in structured *** approach provides effective guidance to AAM vehicles,ensuring conflict avoidance,mitigating traffic congestion,reducing travel time,and maintaining safe ***,intelligent learning-based algorithms are developed to provide speed guidance for each AAM vehicle,ensuring secure merging into air corridors and safe passage through *** validate the effectiveness of our proposed model,we conduct training and evaluation using BlueSky,an open-source air traffic control simulation *** the simulation of thousands of aircraft and the integration of real-world data,our study demonstrates the promising potential of MARL in enabling safe and efficient AAM *** simulation results validate the efficacy of our approach and its ability to achieve the desired outcomes.

关键词： Advanced Air Mobility(AAM) Urban Air Mobility(UAM) Air Traffic Control(ATC) Multi-Agent Reinforcement Learning(MARL)

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Fully embedded time series generative adversarial networks

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Neural Computing and Applications 2024年第24期36卷 14885-14894页

作者： Beck, Joe Chakraborty, Subhadeep Department of Mechanical Aerospace and Biomedical Engineering University of Tennessee KnoxvilleTN United States

Generative adversarial networks should produce synthetic data that fits the underlying distribution of the data being modeled. For real-valued time series data, this implies the need to simultaneously capture the static distribution of the data, but also the full temporal distribution of the data for any potential time horizon. This temporal element produces a more complex problem that can potentially leave current solutions under-constrained, unstable during training, or prone to varying degrees of mode collapse. In FETSGAN, entire sequences are translated directly to the generator’s sampling space using a seq2seq style adversarial autoencoder, where adversarial training is used to match the training distribution in both the feature space and the lower-dimensional sampling space. This additional constraint provides a loose assurance that the temporal distribution of the synthetic samples will not collapse. In addition, the First Above Threshold operator is introduced to supplement the reconstruction of encoded sequences, which improves training stability and the overall quality of the synthetic data being generated. These novel contributions demonstrate a significant improvement to the current state of the art for adversarial learners in qualitative measures of temporal similarity and quantitative predictive ability of data generated through FETSGAN. © The Author(s), under exclusive licence to Springer-Verlag London Ltd., part of Springer Nature 2024.

关键词： Generative adversarial networks

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Automated and miniaturized screening of antibiotic combinations via robotic-printed combinatorial droplet platform

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Acta Pharmaceutica Sinica B 2024年第4期14卷 1801-1813页

作者： Fangchi Shao Hui Li Kuangwen Hsieh Pengfei Zhang Sixuan Li Tza-Huei Wang Department of Biomedical Engineering Johns Hopkins UniversityBaltimoreMD 21218USA Department of Mechanical Engineering Johns Hopkins UniversityBaltimoreMD 21218USA

Antimicrobial resistance(AMR)has become a global health crisis in need of novel *** this end,antibiotic combination therapies,which combine multiple antibiotics for treatment,have at-tracted significant attention as a potential approach for combating *** facilitate advances in anti-biotic combination therapies,most notably in investigating antibiotic interactions and identifying synergistic antibiotic combinations however,there remains a need for automated high-throughput plat-forms that can create and examine antibiotic combinations on-demand,at scale,and with minimal reagent *** address these challenges,we have developed a Robotic-Printed Combinatorial Droplet(RoboDrop)platform by integrating a programmable droplet microfuidic device that generates antibiotic combinations in nanoliter droplets in automation,a robotic arm that arranges the droplets in an array,and a camera that images the array of thousands of droplets in *** further implement a resazurin-based bacterial viability assay to accelerate our antibiotic combination *** a demonstration,we use RoboDrop to corroborate two pairs of antibiotics with known interactions and subsequently identify a new synergistic combination of cefsulodin,penicillin,and oxacillin against a model *** *** therefore envision RoboDrop becoming a useful tool to efficiently identify new synergistic antibiotic combinations toward combating AMR.

关键词： Droplet microfluidics Antimicrobial resistance Antibiotic combinatorial screening Contact printing Robotics Pharmaceutical analysis High-throughput Antibiotic interactions

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Effect of Periodical Wall Shear Stress on Cultured Cell: Design of Couette Flow Device 15

Effect of Periodical Wall Shear Stress on Cultured Cell: Des...

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15th International Multi-Conference on Complexity, Informatics and Cybernetics, IMCIC 2024

作者： Takabe, Yuuki Hashimoto, Shigehiro Biomedical Engineering Mechanical Engineering Kogakunin University Tokyo Japan Biomedical Engineering Department of Mechanical Engineering Kogakunin University Tokyo Japan

ISBN: (纸本)9781950492787

Endothelial cells are oriented in the direction of blood flow on the inner wall of blood vessels. Endothelial cells are exposed to pulsatile flow and are subjected to periodic wall shear stress. In this study, a device was designed to apply periodically fluctuating shear stress to cells. A Couette-type flow was generated in the culture medium sandwiched between a rotating disk and a stationary culture plate. By periodically varying the rotational speed of the disk in a rectangular wave pattern, periodically varying shear stress was applied to the culture wall surface. The device was placed in an incubator so that cells in culture could be continuously observed under a microscope while being exposed to a cyclic shear stress field. The flow of the culture medium was measured by tracking the floating cells as tracers. It was confirmed that the flow fluctuated in a rectangular wave pattern following the rotation of the disk. This device allows observation of the behavior of cultured cells under periodic wall shear stress. Research on cellular responses to mechanical stimulation is expected to be applied to regenerative medicine through tissue formation. © IMCIC 2024. All rights reserved.

关键词： Shear stress

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