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Direct measurement of unsteady microscale Stokes flow using optically driven microspheres

Physical Review Fluids 2021年第5期6卷 053102-053102页

作者： Nicolas Bruot Pietro Cicuta Hermes Bloomfield-Gadêlha Raymond E. Goldstein Jurij Kotar Eric Lauga François Nadal Cavendish Laboratory and Nanoscience Centre University of Cambridge Cambridge CB3 0HE United Kingdom Institut de Physique de Nice CNRS UMR No. 7010 Université Côte d'Azur 06108 Nice France Department of Engineering Mathematics & Bristol Robotics Laboratory University of Bristol Bristol BS8 1UB United Kingdom Department of Applied Mathematics and Theoretical Physics Centre for Mathematical Sciences University of Cambridge Cambridge CB3 0WA United Kingdom Wolfson School of Mechanical Electrical and Manufacturing Engineering Loughborough University Loughborough LE11 3TU United Kingdom

A growing body of work on the dynamics of eukaryotic flagella has noted that their oscillation frequencies are sufficiently high that the viscous penetration depth of unsteady Stokes flow is comparable to the scales over which flagella synchronize. Incorporating these effects into theories of synchronization requires an understanding of the global unsteady flows around oscillating bodies. Yet, there has been no precise experimental test on the microscale of the most basic aspects of such unsteady Stokes flow: the orbits of passive tracers and the position-dependent phase lag between the oscillating response of the fluid at a distant point and that of the driving particle. Here, we report the first such direct Lagrangian measurement of this unsteady flow. The method uses an array of 30 submicron tracer particles positioned by a time-shared optical trap at a range of distances and angular positions with respect to a larger, central particle, which is then driven by an oscillating optical trap at frequencies up to 400 Hz. In this microscale regime, the tracer dynamics is considerably simplified by the smallness of both inertial effects on particle motion and finite-frequency corrections to the Stokes drag law. The tracers are found to display elliptical Lissajous figures whose orientation and geometry are in agreement with a low-frequency expansion of the underlying dynamics, and the experimental phase shift between motion parallel and orthogonal to the oscillation axis exhibits a predicted scaling form in distance and angle. Possible implications of these results for synchronization dynamics are discussed.

关键词： Fluid-particle interactions Swimming Lagrangian particle tracking Navier-Stokes equation

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Electrochemical removal of amphoteric ions

arXiv

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arXiv 2021年

作者： Shocron, Amit N. Guyes, Eric N. Maarten Biesheuvel, P. Rijnaarts, Huub H.M. Suss, Matthew E. Dykstra, Jouke E. Faculty of Mechanical Engineering Technion - Israel Institute of Technology Haifa Israel Wetsus European Centre of Excellence for Sustainable Water Technology Oostergoweg 9 Leeuwarden8911 MA Netherlands Environmental Technology Wageningen University Bornse Weilanden 9 Wageningen6708 WG Netherlands Grand Technion Energy Program Technion - Israel Institute of Technology Haifa Israel Wolfson Department of Chemical Engineering Technion - Israel Institute of Technology Haifa Israel

Several harmful or valuable ionic species present in sea, brackish and wastewaters are amphoteric, and thus their properties depend on the local water pH. Effective removal of these species can be challenging by conventional membrane technologies, necessitating chemical dosing of the feedwater to adjust its pH. Capacitive deionization (CDI) is an emerging membraneless technique for water treatment and desalination, based on electrosorption of salt ions into charging microporous electrodes. CDI cells show strong internally-generated pH variations during operation, and thus CDI can potentially remove amphoteric species without chemical dosing. However, development of this technique is inhibited by the complexities inherent to coupling of pH dynamics and amphoteric ion properties in a charging CDI cell. Here, we present a novel theoretical framework predicting the electrosorption of amphoteric species in flow-through electrode CDI cells. We demonstrate that such a model enables deep insight into factors affecting amphoteric species electrosorption, and conclude that important design rules for such systems are highly counter-intuitive. For example, we show both theoretically and experimentally that for boron removal the anode should be placed upstream, which runs counter to accepted wisdom in the CDI field. Overall, we show that to achieve target separations relying on coupled, complex phenomena, such as in the removal of amphoteric species, a theoretical CDI model is essential. Copyright © 2021, The Authors. All rights reserved.

关键词： Membrane technology

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Compliant net for AUV retrieval using a UAV

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IFAC-PapersOnLine 2018年第29期51卷 431-437页

作者： Ivanovic, Antun Polic, Marsela Salah, Omar Orsag, Matko Bogdan, Stjepan Laboratory for Robotics and Intelligent Control Systems Faculty of Electrical Engineering and Computing University of Zagreb Unska 3 Zagreb10 000 Croatia Mechanical Engineering Department Faculty of Engineering Assiut University Assiut Egypt

This paper addresses the problem of retrieving an autonomous underwater vehicle (AUV) with an unmanned aerial vehicle (UAV). The design of the compliant net that naturally adapts to the payload morphology is proposed as a retrieval tool. We constructed the proposed compliant net and conducted experiments with an underwater vehicle model as payload. Furthermore, mathematical model of a system comprised of the UAV and the payload is presented and a mid-ranging controller is utilized for such a system. We also present simulation results and analyze the stability of the UAV with the cable attached payload. © 2018

关键词： Autonomous underwater vehicles Antennas Unmanned aerial vehicles (UAV) Autonomous underwater vehicles (AUV) Marine systems mechanical design Retrieval tool Soft robotics Underwater vehicles

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Harnessing Machine Learning for Quantum-Accurate Predictions of Non-Equilibrium Behavior in 2D Materials

arXiv

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arXiv 2025年

作者： Zhang, Yue Appleton, Robert J. Lin, Kui McCarthy, Megan J. Paci, Jeffrey T. Sankaranarayanan, Subramanian K.R.S. Strachan, Alejandro Espinosa, Horacio D. Department of Mechanical Engineering Northwestern University EvanstonIL60208 United States School of Materials Engineering Purdue University West LafayetteIN47907 United States Department of Civil and Environmental Engineering The Hong Kong Polytechnic University 999077 Hong Kong Center for Computing Research Computational Multiscale Department Sandia National Laboratories AlbuquerqueNM87185 United States Department of Chemistry University of Victoria VictoriaBCV8W 3V6 Canada Center for Nanoscale Materials Argonne National Laboratory LemontIL60439 United States Theoretical and Applied Mechanics Program Northwestern University EvanstonIL60208 United States

Accurately predicting the non-equilibrium mechanical properties of two-dimensional (2D) materials is essential for understanding their deformation, thermo-mechanical properties, and failure mechanisms. In this study, we parameterize and evaluate two machine learning (ML) interatomic potentials, SNAP and Allegro, for modeling the non-equilibrium behavior of monolayer MoSe2. Using a density functional theory (DFT) derived dataset, we systematically compare their accuracy and transferability against the physics-based Tersoff force field. Our results show that SNAP and Allegro significantly outperform Tersoff, achieving near-DFT accuracy while maintaining computational efficiency. Allegro surpasses SNAP in both accuracy and efficiency due to its advanced neural network architecture. Both ML potentials demonstrate strong transferability, accurately predicting out-of-sample properties such as surface stability, inversion domain formation, and fracture toughness. Unlike Tersoff, SNAP and Allegro reliably model temperature-dependent edge stabilities and phase transformation pathways, aligning closely with DFT benchmarks. Notably, their fracture toughness predictions closely match experimental measurements, reinforcing their suitability for large-scale simulations of mechanical failure in 2D materials. This study establishes ML-based force fields as a powerful alternative to traditional potentials for modeling non-equilibrium mechanical properties in 2D materials. Copyright © 2025, The Authors. All rights reserved.

关键词： Fracture toughness

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Improved dynamic window approach with ellipse equations for autonomous navigation of unmanned surface vehicle

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Journal of Institute of Control, robotics and Systems 2020年第8期26卷 624-629页

作者： Kim, Hyogon Yun, Sung-Jo Choi, Young-Ho Ryu, Jae-Kwan Won, Byong-Jae Suh, Jin-Ho Korea Institute of Robotics and Technology Convergence Korea Republic of Unmanned/Intelligent Robotic Systems R&D Lab. LIG Nex1 Korea Republic of Department. of Mechanical System Engineering Pukyoung National University Korea Republic of

Autonomous navigation technology for Unmanned Surface Vehicles (USVs) has seen many recent advancements. In order for a USV to operate autonomously, the path to move from its current location to its destination must be planned, and local path planning must be applied for tracking the path and avoiding obstacles. The Dynamic Window Approach (DWA) is a well-known navigation algorithm used for local path planning. The DWA algorithm derives the linear velocity and angular velocity by evaluating the object function defined as destination direction, velocity, and distance from the obstacle. However, because DWA does not consider the velocity and direction of obstacles, USVs may be in danger when avoiding high-speed obstacles. In this paper, we propose an improved DWA algorithm that considers the velocity and direction of obstacles. Whereas the existing DWA algorithm defines the obstacle recognition area as a circle, the proposed DWA algorithm defines the obstacle recognition area as an ellipse and reflects the speed of the obstacle in the ellipse. In this study, we implemented a simulation to compare the existing DWA algorithm with the improved DWA algorithm proposed here. The results confirm that the proposed DWA algorithm can avoid dynamic obstacles more safely than the existing DWA algorithm. © ICROS 2020.

关键词： Unmanned surface vehicles

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Calculations of the steam boiler operation factors under varying operating conditions using a thermodynamics modeling 32

Calculations of the steam boiler operation factors under var...

引用

32nd International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems, ECOS 2019

作者： Madejski, Pawel Żymelka, Piotr AGH University of Science and Technology Faculty of Mechanical Engineering and Robotics Department of Power Systems and Environmental Protection Facilities Kraków Poland PGE Energia Ciepla S.A. Production Economics Department Rybnik Poland Silesian University of Technology Faculty of Energy and Environmental Engineering Institute of Thermal Technology Gliwice Poland

ISBN: (纸本)9788361506515

The paper presents results of a steam boiler operation modeling fired with hard coal. The thermodynamic model developed is consisted of basic components of the steam boiler for both the flue gases-air and water-steam circuits. The results in the form and steam temperature distributions have been verified with available boiler measurement data. The developed model in the Ebsilon software allows performing calculations for variable input conditions in order to enable the basic parameters of the boiler operation. In the presented work the possibility of identifying the changing properties of the fuel burned in the boiler and its impact on operating conditions was verified. Simulations were carried out for variable boiler operating conditions such as fuel quality and quantity, and variable load. The results were presented in the form of total boiler efficiency and boiler losses. To analyzed boiler performance, an energetic and exergetic efficiency of the boiler was calculated using the developed procedure. The analysis consists of boiler operation simulations for different coal and at different partial load. © ECOS 2019 - Proceedings of the 32nd International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems. All rights reserved.

关键词： Energy efficiency

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Correction: Direct laser writing-enabled 3D printing strategies for microfluidic applications

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Lab on a chip 2024年第9期24卷 2590页

作者： Olivia M Young Xin Xu Sunandita Sarker Ryan D Sochol Department of Mechanical Engineering University of Maryland College Park 2147 Glenn L. Martin Hall College Park MD 20742 USA. rsochol@umd.edu. Maryland Robotics Center University of Maryland College Park MD 20742 USA. Institute for Systems Research University of Maryland College Park MD 20742 USA. Department of Mechanical and Industrial Engineering University of Massachusetts Amherst MA 01003 USA. Fischell Department of Bioengineering University of Maryland College Park MD 20742 USA. Robert E. Fischell Institute for Biomedical Devices University of Maryland College Park MD 20742 USA.

Correction for 'Direct laser writing-enabled 3D printing strategies for microfluidic applications' by Olivia M. Young , , 2024, DOI: https://***/10.1039/D3LC00743J.

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Seebeck Coefficient in a Cuprate Superconductor: Particle-Hole Asymmetry in the Strange Metal Phase and Fermi Surface Transformation in the Pseudogap Phase

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Physical Review X 2022年第1期12卷 011037-011037页

作者： A. Gourgout G. Grissonnanche F. Laliberté A. Ataei L. Chen S. Verret J.-S. Zhou J. Mravlje A. Georges N. Doiron-Leyraud Louis Taillefer Institut Quantique Département de physique and RQMP Université de Sherbrooke Sherbrooke Québec Canada Laboratory of Atomic and Solid State Physics Cornell University Ithaca New York USA Kavli Institute at Cornell for Nanoscale Science Ithaca New York USA Materials Science and Engineering Program/Mechanical Engineering University of Texas-Austin Austin Texas USA Department of Theoretical Physics Institute Jožef Stefan Ljubljana Slovenia Collège de France 11 place Marcelin Berthelot Paris France Center for Computational Quantum Physics Flatiron Institute New York New York USA CPHT CNRS Ecole Polytechnique IP Paris Palaiseau France DQMP Université de Genève Geneva Switzerland Canadian Institute for Advanced Research Toronto Ontario Canada

We report measurements of the Seebeck effect in both the ab plane (Sa) and along the c axis (Sc) of the cuprate superconductor La1.6−xNd0.4SrxCuO4 (Nd-LSCO), performed in magnetic fields large enough to suppress superconductivity down to low temperature. We use the Seebeck coefficient as a probe of the particle-hole asymmetry of the electronic structure across the pseudogap critical doping p⋆=0.23. Outside the pseudogap phase, at p=0.24>p⋆, we observe a positive and essentially isotropic Seebeck coefficient as T→0. That S>0 at p=0.24 is at odds with expectations given the electronic band structure of Nd-LSCO above p⋆ and its known electronlike Fermi surface. We can reconcile this observation by invoking an energy-dependent scattering rate with a particle-hole asymmetry, possibly rooted in the non-Fermi-liquid nature of cuprates just above p⋆. Inside the pseudogap phase, for p

关键词： Superconductivity Strongly correlated systems

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Burr- And Etch-Free Direct Machining of Shape-Controlled Micro- And Nanopatterns on Polyimide Films by Continuous Nanoinscribing for Durable Flexible Devices

SSRN

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SSRN 2021年

作者： Oh, Dong Kyo Lee, Wonseok Chae, Hyoungseok Chun, Hyunsoo Lee, Minyoung Kim, Dong Ha Kim, Joohoon Choi, Jaemin Hwang, Sangwon Park, Minyong Yeon, Gyubeom Jung, Sunmin Rho, Junsuk Ok, Jong G. Department of Mechanical and Automotive Engineering Seoul National University of Science and Technology Seoul01811 Korea Republic of Pohang37673 Korea Republic of Graduate Program of Energy Technology School of Integrated Technology Institute of Integrated Technology Gwangju Institute of Science and Technology Gwangju61005 Korea Republic of Pohang37673 Korea Republic of

Polyimide (PI) is one of the most pragmatic polymers for highly durable flexible devices based on its micro- and nanopatterned structures, because of its excellent thermal and chemical stability. The conventional top-down patterning processes, typically involving materials removal and chemical etching, however, are often ineffective to fabricate micro- and nanopatterns on the PI film due to its high mechanical and chemical resistance. In this work, we develop a highly efficient and scalable PI patterning methodology by utilizing the burr- and etch-free direct mechanical deformation driven by continuous dynamic nanoinscribing. We systematically investigate that the micro- and nanopatterns can be cleanly machined on the PI film with tailored periods, depths, and shapes, by controlling several key nanoinscribing process parameters such as temperature and force. Among many potential applications that can benefit from the present study, we demonstrate the facile fabrication of metallic micro- and nanowires, either durably embedded in or etch-freely patterned on the PI surface, toward flexible and highly durable device systems. © 2021, The Authors. All rights reserved.

关键词： Polyimides

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A Hybrid Optimization Approach Towards Energy Recovery from Torrefied Waste Blends

SSRN

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SSRN 2022年

作者： Silveira, Edgar Amaral Chaves, Bruno Santanna Macedo, Lucélia Ghesti, Grace F. Evaristo, Rafael B.W. Lamas, Giulia Cruz Luz, Sandra M. de Paula Protásio, Thiago Rousset, Patrick Mechanical Sciences Graduate Program University of Brasília Brasília – DF Brazil Forest Engineering Department University of Brasília DF Brasília70910-900 Brazil Laboratory of Brewing Bioprocesses and Catalysis to Renewable Energy Chemistry Institute University of Brasilia Brasilia-DF70910-900 Brazil Parauapebas Pará CEP 68515-000 Brazil CIRAD UPR BioWooEB MontpellierF-34398 France BioWooEB Univ. Montpellier CIRAD Montpellier France

The bottleneck of urban forest waste (UFW) as biofuel relies on surpassing its logistical management, feedstock supply, heterogeneity, and property drawbacks. This article proposes a hybrid approach based on multicriteria decision methods (MCDM) and response surface methodology (RSM) to optimize the definition of UFW blends and their torrefaction (temperature and process time). First, the physicochemical characteristics (proximate, ultimate, and calorific) of six wood wastes (Mangifera indica, Ficus benjamina, Pelthophorum dubium, Persea americana, Anadenanthera colubrina and Tapirira guianensis) were assessed. Then, based on the understanding that wastes rely on distinct species that do not show promising properties as biofuels, an optimum blend (OB) was determined by MCDM. Next, the OB torrefaction was optimized using a central composite design (RSM-CCD) model. Therefore, providing the optimum condition and a torrefied optimum blend (TOB). Finally, the approach was validated by assessing optimized blends' properties, combustion behavior, and gaseous emissions. The methodology provided a TOB with lower ash (2.67%), a higher heating value of 20.87 ***-1, reduced nitrogen content (up to 39.65%) and more stable combustion resulting in a superior solid biofuel with a lower potential of NO-emissions in further applications. The results might guide resource-efficient urban planning and insights into urban feedstock proception. © 2022, The Authors. All rights reserved.

关键词： Waste management

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