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OCEANS

作者： E.M. Mule P.J. Haley C. Mirabito S.F. DiMarco S. Mahmud A. Dancer X. Ge A.H. Knap Y. Liu U.C. Nwankwo S. Glenn T.N. Miles D. Aragon K. Coleman M. Smith M. Leber R. Ramos J. Storie G. Stuart J. Marble P. Barros E.P. Chassignet A. Bower H.H. Furey B. Jaimes De La Cruz L.K. Shay M. Tenreiro E. Pallas Sanz J. Sheinbaum P. Perez-Brunius D. Wilson J. Van Smirren R. Monreal-Jiménez D.A. Salas-de-León V.K. Contreras Tereza M. Feldman M. Khadka P.F.J. Lermusiaux Department of Mechanical Engineering Massachusetts Institute of Technology Cambridge MA Department of Oceanography Texas A&M University Department of Marine and Coastal Sciences Rutgers University Woods Hole Group Inc. Fugro Department of Earth Ocean and Atmospheric Science Florida State University Physical Oceanography Woods Hole Oceanographic Institution Rosenstiel School of Marine Atmospheric and Earth Science University of Miami Department of Oceanography CICESE University of the Virgin Islands Ocean Sierra Universidad Nacional Autónoma de Mexico Mexican Institute of Water Technology Gulf Research Program NASEM

ISBN: (数字)9798331540081

ISBN: (纸本)9798331540098

As part of the Mini-Adaptive Sampling Test Run (MASTR) experiment in the Gulf of Mexico (GoM) region from February to April 2024, we demonstrated real-time deterministic and probabilistic reachability analysis and time-optimal path planning to guide a fleet of four ocean gliders. The governing differential equations for reachability analysis and time-optimal path planning were numerically integrated in real-time and forced by currents from our large-ensemble ocean forecasts. We illustrate the real-time deterministic and probabilistic forward reachability analyses, reachability and path planning for glider pickups, time-optimal path planning for gliders in distress, and planning of future glider deployments. Results show that the actual paths of gliders were contained within our reachable set forecasts and in accord with the dynamic reachability fronts. Our time-optimal headings and paths also predicted real glider motions, even for longer-range predictions of weeks to a month duration. Reachability and time-optimal path planning forecasts were successfully employed for glider recovery. They also enabled exploring options for future glider deployments.

关键词： Uncertainty Oceans Dynamics Differential equations Probabilistic logic Path planning Real-time systems Hazards Reachability analysis Vehicle dynamics

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Transferable screened range-separated hybrid functionals for electronic and optical properties of van der Waals materials

arXiv

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arXiv 2023年

作者： Camarasa-Gómez, María Ramasubramaniam, Ashwin Neaton, Jeffrey B. Kronik, Leeor Department of Molecular Chemistry and Materials Science Weizmann Institute of Science Rehovoth7610001 Israel Department of Mechanical and Industrial Engineering University of Massachusetts Amherst AmherstMA01003 United States Materials Science and Engineering Graduate Program University of Massachusetts Amherst AmherstMA01003 United States Department of Physics University of California BerkeleyCA94720 United States Materials Sciences Division Lawrence Berkeley National Laboratory BerkeleyCA94720 United States Kavli Energy NanoSciences Institute at Berkeley University of California BerkeleyCA94720 United States

The accurate description of electronic properties and optical absorption spectra is a long-standing challenge for density functional theory. Recently, the introduction of screened range-separated hybrid (SRSH) functionals for solid-state materials has allowed for the calculation of fundamental band gaps and optical absorption spectra that are in very good agreement with many-body perturbation theory. However, since solid-state SRSH functionals are typically tuned to reproduce the properties of bulk phases, their transferability to low-dimensional structures, which experience substantially different screening than in the bulk, remains an open question. In this work, we explore the transferability of SRSH functionals to several prototypical van der Waals materials, including transition-metal sulfides and selenides, indium selenide, black phosphorus, and hexagonal boron nitride. Considering the bulk and a monolayer of these materials as limiting cases, we show that the parameters of the SRSH functional can be determined systematically, using only the band-edge quasiparticle energies of these extremal structural phases as fitting targets. The resulting SRSH functionals can describe both electronic bandstructures and optical absorption spectra with accuracy comparable to more demanding ab initio many-body perturbation theory (GW and Bethe-Salpeter equation) approaches. Selected examples also demonstrate that the SRSH parameters, obtained from the bulk and monolayer reference structures, display good accuracy for bandstructures and optical spectra of bilayers, indicating a degree of transferability that is independent of the fitting procedure. Copyright © 2023, The Authors. All rights reserved.

关键词： Transition metals

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The strain and deflection analysis of wire mesh layer in hot asphalt mixtures using finite element method

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AIP Conference Proceedings 2023年第1期2711卷

作者： Romaynoor Ismy Sofyan M. Saleh Husaini M. Isya Doctoral Program School of Engineering Post Graduate Program Universitas Syiah Kuala Banda Aceh 23111 Indonesia Department of Civil Engineering Universitas Almuslim Matangglumpangdua 24261 Indonesia Department of Civil Engineering Universitas Syiah Kuala Banda Aceh 23111 Indonesia Department of Mechanical Engineering Universitas Syiah Kuala Banda Aceh 23111 Indonesia

Strain is closely related to the amount of load that can be held by an object so that it experiences deflection. A change in the size or shape of an object in holding a load causing stress is called strain. Strain and stress are forces that act on an object due to loads. The distribution analysis of the strain is needed to determine the phenomena that occur in an object due to loads to facilitate the analysis of wire mesh placement modeling. This research aimed to analyze the strain and deflection values that occur due to the loading of wire mesh layer on hot asphalt mixture. Analysis of strain and deflection values which are parameters of flexural resistance was carried out using ETABS software version 17.0.1. ETABS is one of the software used to solve structural problems related to the finite element method. Based on the research results, it was found that the modeling of wire mesh layering affects the flexural resistance value, strain, and deflection that occurred. The value of strain is inversely proportional to the value of the flexural resistance and is directly proportional to the deflection. The strain that occurs from the results of the study is between 0.0313 mm/mm to 0.038 mm/mm and The amount of deflection that occurs due to loading ranges from 8 to 9.5 mm. The best modeling is obtained on a hot asphalt mixture by laying wire mesh 30 mm from the surface of the test object with the lowest strain and able to withstand a maximum load of 291.85 KN.

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Weak-value amplification for the optical signature of topological phase transitions

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Photonics Research 2020年第12期8卷 I0015-I0022页

作者： WEIJIE WU SHIZHEN CHEN WENHAO XU ZHENXING LIU RUNNAN LOU LIHUA SHEN HAILU LUO SHUANGCHUN WEN XIAOBO YIN Laboratory for Spin Photonics School of Physics and ElectronicsHunan UniversityChangsha 410082China Department of Mechanical Engineering University of ColoradoBoulderColorado 80309USA Materials Science and Engineering Program University of ColoradoBoulderColorado 80309USA

We show that weak measurements can be used to measure the tiny signature of topological phase *** signature is an in-plane photonic spin Hall effect,which can be described as a consequence of a Berry *** is also parallel to the propagation direction of a light *** imaginary part of the weak value can be used to analyze ultrasmall longitudinal phase shifts in different topological *** optical signatures are related to the Chern number and bandgaps;we also use a preselection and postselection technique on the spin state to enhance the original *** weak amplification technique offers a potential way to determine the spin and valley properties of charge carriers,Chern numbers,and topological phases by direct optical measurement.

关键词： signature topological transitions

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Review of surgical robotic systems for keyhole and endoscopic procedures:state of the art and perspectives

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Frontiers of Medicine 2020年第4期14卷 382-403页

作者： Yuyang Chen Shu’an Zhang Zhonghao Wu Bo Yang Qingquan Luo Kai Xu State Key Laboratory of Mechanical System and Vibration School of Mechanical EngineeringShanghai Jiao Tong UniversityShanghai 200240China RII Lab(Lab of Robotics Innovation and Intervention) UM-SJTU Joint InstituteShanghai Jiao Tong UniversityShanghai 200240China Department of Urology Shanghai Changhai Hospitalthe Second Military Medical UniversityShanghai 200433China Shanghai Lung Cancer Center Shanghai Chest HospitalShanghai Jiao Tong UniversityShanghai 200030China

Minimally invasive surgery,including laparoscopic and thoracoscopic procedures,benefits patients in terms of improved postoperative outcomes and short recovery *** challenges in hand–eye coordination and manipulation dexterity during the aforementioned procedures have inspired an enormous wave of developments on surgical robotic systems to assist keyhole and endoscopic procedures in the past *** paper presents a systematic review of the state-of-the-art systems,picturing a detailed landscape of the system configurations,actuation schemes,and control approaches of the existing surgical robotic systems for keyhole and endoscopic *** development challenges and future perspectives are discussed in depth to point out the need for new enabling technologies and inspire future researches.

关键词： surgical robots keyhole surgery endoscopic surgery

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Thermal conductivity modeling of monodispersed microspheres using discrete element method

arXiv

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arXiv 2021年

作者： Zeng, Jian Chung, Ka Man Zhang, Xintong Adapa, Sarath Feng, Tianshi Pei, Yu Chen, Renkun Department of Mechanical and Aerospace Engineering University of California San Diego San DiegoCA92093 United States Material Science and Engineering Program University of California San Diego San DiegoCA92093 United States

Particle beds are widely used in various systems and processes, such as particle heat exchangers, granular flow reactors, and additive manufacturing. Accurate modeling of thermal conductivity of particle beds and understanding of their heat transfer mechanisms are important. However, previous models were based on a simple cubic packing of particles which could not accurately represent the actual heat transfer processes under certain conditions. Here, we examine the effect of the packing structure on thermal conductivity of particle beds. We use monodispersed silica microspheres with average article sizes ranging from 23 to 330 µm as a model material. We employ a transient hot-wire technique to measure the thermal conductivity of the particle beds with packing density of 43 to 57% within a temperature range of room temperature to 500℃ and under N2 gaseous pressures of 20 to 760 Torr. We then use a discrete element method (DEM) to obtain the realistic packing structure of the particles, which is then fed into a finite-element model (FEM) to calculate the thermal conductivity, with the consideration of solid conduction, gas conduction, and radiation heat transfer. Our results show that the thermal conductivity model based on the more realistic random packing structure derived from the DEM shows better agreement with the experimental data compared to that based on the simple cubic packing structure. The combined DEM and FEM methodology can serve as a useful tool to predict effective thermal conductivity of particle beds and to quantify different heat transfer mechanisms under various conditions. © 2021, CC BY-NC-ND.

关键词： Finite element method

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Real-time Ocean Probabilistic Forecasts, Reachability Analysis, and Adaptive Sampling in the Gulf of Mexico

Real-time Ocean Probabilistic Forecasts, Reachability Analys...

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OCEANS

作者： P.F.J. Lermusiaux P.J. Haley C. Mirabito E.M. Mule S.F. DiMarco A. Dancer X. Ge A.H. Knap Y. Liu S. Mahmud U.C. Nwankwo S. Glenn T.N. Miles D. Aragon K. Coleman M. Smith M. Leber R. Ramos J. Storie G. Stuart J. Marble P. Barros E.P. Chassignet A. Bower H.H. Furey B. Jaimes de la Cruz L.K. Shay M. Tenreiro E. Pallas Sanz J. Sheinbaum P. Perez-Brunius D. Wilson J. van Smirren R. Monreal-Jiménez D.A. Salas-de-León V.K. Contreras Tereza M. Feldman M. Khadka Department of Mechanical Engineering Massachusetts Institute of Technology Cambridge MA Department of Oceanography Texas A&M University Department of Marine and Coastal Sciences Rutgers University Woods Hole Group Inc. Fugro Department of Earth Ocean and Atmospheric Science Florida State University Physical Oceanography Woods Hole Oceanographic Institution Rosenstiel School of Marine Atmospheric and Earth Science University of Miami Department of Oceanography CICESE University of the Virgin Islands Ocean Sierra Universidad Nacional Autónoma de México Mexican Institute of Water Technology Gulf Research Program NASEM

ISBN: (数字)9798331540081

ISBN: (纸本)9798331540098

The first steps towards integrating autonomous monitoring, probabilistic forecasting, reachability analysis, and adaptive sampling for the Gulf of Mexico were demonstrated in real-time during the collaborative Mini-Adaptive Sampling Test Run (MASTR) ocean experiment, which took place from February to April 2024. The emphasis of this contribution is on the use of the MIT Multidisciplinary Simulation, Estimation, and Assimilation Systems (MSEAS) including Error Subspace Statistical Estimation (ESSE) large-ensemble forecasting and path planning systems to predict ocean fields and uncertainties, forecast reachable sets and optimal paths for gliders, and guide sampling aircraft and ocean vehicles toward the most informative observations. Deterministic and probabilistic ocean forecasts are exemplified and linked to the variability of the Loop Current (LC) and LC Eddies, demonstrating predictive skill by real-time comparisons to independent data. Risk forecasts in terms of probabilities of currents exceeding 1.5 kt were provided. The most informative sampling patterns for Remote Ocean Current Imaging System (ROCIS) flights were forecast using mutual information between surface currents and density anomaly. Finally, we guided four underwater gliders using probabilistic reachability and path-planning forecasts.

关键词： Oceans Atmospheric modeling Estimation Predictive models Probabilistic logic Real-time systems Wind forecasting Reachability analysis Integrated circuit modeling Forecasting

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In-situ thermal transport measurement of flowing fluid using modulated photothermal radiometry

arXiv

引用

arXiv 2021年

作者： Zeng, Jian Chung, Ka Man Adapa, Sarath Reddy Feng, Tianshi Chen, Renkun Department of Mechanical and Aerospace Engineering University of California San Diego San DiegoCA92093 United States Program of Material Science and Engineering University of California San Diego San DiegoCA92093 United States

In situ thermal transport measurement of flowing fluid could be useful for the characterization and diagnosis of practical thermal systems such as fluid heat exchangers and thermal energy storage systems. Despite abundant reports on the ex-situ thermal conductivity measurement of stagnant fluids, a suitable technique for the thermal conductivity measurement of flowing fluid has been rarely reported. This paper presents the thermal conductivity measurement of flowing fluid within a pipe using a non-contact modulated photothermal radiometry (MPR) technique, where the surface of the pipe is heated by an intensity-modulated laser and the heat diffuses into the fluid with suitable modulation frequency. We design a tube section with small wall thickness suitable for the MPR measurements to maximize the sensitivity of the thermal response to the fluid properties while minimizing the lateral heat spreading effect. Intrinsic thermal conductivity of different fluids was obtained within a proper range of frequency and flow velocity where the forced convection effect is negligible. The forced convection effect became prominent at high flowing velocity and at low modulation frequency, leading to overestimated thermal conductivity of fluid. It is found that the intrinsic thermal conductivity could be obtained when the flow velocity is less than 100 mm/sec and ReD1/2Pr1/3 Copyright © 2021, The Authors. All rights reserved.

关键词： Prandtl number

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Performance Evaluation of Carbon-Based Nanofluids for Direct Absorption Solar Collector

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Energies 2023年第3期16卷 1157页

作者： Yu, Shang-Pang Teng, Tun-Ping Huang, Chia-Cing Hsieh, Hsiang-Kai Wei, Yi-Jia Department of Mechanical Engineering National Taipei University of Technology No. 1 Sec. 3 Zhongxiao E. Rd. Taipei10608 Taiwan Undergraduate Program of Vehicle and Energy Engineering National Taiwan Normal University No. 162 Sec. 1 He-Ping E. Road Da-An District Taipei10610 Taiwan Department of Industrial Education National Taiwan Normal University No. 162 Sec. 1 He-Ping E. Road Da-An District Taipei10610 Taiwan

In this study, carbon-based nanofluids (CBNFs) were prepared using a revised vortex trap method and applied in the direct absorption solar collector (DASC) to evaluate the feasibility of CBNFs in DASC. The thermal storage performance of water and different concentrations of CBNFs (0.01, 0.025 and 0.05 wt%) was assessed with a 1000 W halogen lamp as a simulated light source under different volumetric flow rates (1.5, 3.0, and 4.5 L per minute [LPM]) at a constant thermal storage load (2.4 kg of water) and ambient temperature of 26 °C. The thermal storage capacity, system efficiency factor (SEF), and heating rate of the CBNFs as the working fluid were higher than those of water in most cases. The thermal storage capacity and SEF of 0.05 wt% CBNF at a volumetric flow rate of 3.0 LPM were 10.36% and 9.36% higher than that of water, respectively. The relevant experimental results demonstrate the great potential of CBNFs in DASC. © 2023 by the authors.

关键词： Carbon

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Breakdown of Conventional Winding Number Calculation in One-Dimensional Lattices with Interactions Beyond Nearest Neighbors

arXiv

引用

arXiv 2023年

作者： Alisepahi, Amir Rajabpoor Sarkar, Siddhartha Sun, Kai Ma, Jihong Department of Mechanical Engineering University of Vermont 33 Colchester Ave BurlingtonVT05405 United States Department of Physics University of Michigan 450 Church St. Ann ArborMI48109 United States Department of Physics University of Vermont 33 Colchester Ave BurlingtonVT05405 United States Materials Science Program University of Vermont 33 Colchester Ave BurlingtonVT05405 United States

Topological insulators hold promises to realize exotic quantum phenomena in electronic, photonic, and phononic systems. Conventionally, topological indices, such as winding numbers, have been used to predict the number of topologically protected domain-wall states (TPDWSs) in topological insulators, a signature of the topological phenomenon called bulk-edge correspondence. Here, we demonstrate theoretically and experimentally that the number of TPDWSs in a mechanical Su-Schrieffer-Heeger (SSH) model can be higher than the winding number depending on the strengths of beyond-nearest-neighbor interactions, revealing the breakdown of the winding number prediction. Alternatively, we resort to the Berry connection to accurately characterize the number and spatial features of TPDWSs in SSH systems, further confirmed by the Jackiw-Rebbi theory proving that the multiple TPDWSs correspond to the bulk Dirac cones. Our findings deepen the understanding of complex network dynamics and offer a generalized paradigm for precise TPDWS prediction in potential applications involving localized vibrations, such as drug delivery and quantum computing. © 2023, CC BY.

关键词： Topology

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