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22nd International Conference on Electronics Packaging, ICEP 2023

作者： Abdul Razak, Nurul R. Tan, Xin F. McDonald, Stuart D. Bermingham, Michael J. Venezuela, Jeffery Nishimura, Tetsuro Nogita, Kazuhiro The University of Queensland School of Mechanical and Mining Engineering BrisbaneQLD Australia Faculty of Mechanical Engineering and Technology Perlis Malaysia Perlis Malaysia Kyushu University Department of Applied Quantum Physics and Nuclear Engineering Fukuoka Japan Nihon Superior Co. Ltd. Osaka Suita City Japan

ISBN: (纸本)9784991191152

Exploiting the growth rate dependency of intermetallic compounds (IMCs) on the substrate composition, the possibility of controlling porosity during transient liquid phase (TLP) bonding via a composition gradient is investigated. A Cu substrate with a variable Ni concentration was prepared through selective electroplating and subsequent heat treatment. When this substrate reacted with a molten Sn-rich alloy, there was a non-uniform growth of the Cu6Sn5 IMC. It is proposed that by tailoring the direction of the composition gradient in the substrate, the IMC growth rate can be controlled in such a way as to progressively move the solid-liquid front to redistribute any porosity away from the central region of the joint and thereby improve reliability. © 2023 Japan Institute of Electronics Packaging.

关键词： Porosity

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Agile Fixed-Wing UAVs for Urban Swarm Operations

IEEE Transactions on Field Robotics

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IEEE Transactions on Field Robotics 2024年 1卷 394-423页

作者： Max Basescu Adam Polevoy Bryanna Yeh Luca Scheuer Erin Sutton Joseph Moore Johns Hopkins University Applied Physics Laboratory Laurel MD USA Department of Mechanical Engineering Johns Hopkins University Baltimore MD USA

Fixed-wing uncrewed aerial vehicles (UAVs) offer significant performance advantages over rotary-wing UAVs in terms of speed, endurance, and efficiency. Such attributes make these vehicles ideally suited for long-range or high-speed reconnaissance operations and position them as valuable complementary members of a heterogeneous multirobot team. However, these vehicles have traditionally been severely limited with regard to both vertical take-off and landing (VTOL) as well as maneuverability, which greatly restricts their utility in environments characterized by complex obstacle fields (e.g., forests or urban centers). This article describes a set of algorithms and hardware advancements that enable agile fixed-wing UAVs to operate as members of a swarm in complex urban environments. At the core of our approach is a direct nonlinear model predictive control (NMPC) algorithm that is capable of controlling fixed-wing UAVs through aggressive poststall maneuvers. We demonstrate in hardware how our online planning and control technique can enable navigation through tight corridors and in close proximity to obstacles. We also demonstrate how our approach can be combined with onboard stereo vision to enable high-speed flight in unknown environments. Finally, we describe our method for achieving swarm system integration; this includes a gimballed propeller design to facilitate automatic take-off, a precision deep-stall landing capability, multivehicle collision avoidance, and software integration with existing swarm architecture.

关键词： Trajectory Robots Real-time systems Navigation Aerodynamics Quadrotors Libraries Planning Autonomous aerial vehicles Attitude control

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A Magnetic-Actuator Based Planar Nano-Positioning System

A Magnetic-Actuator Based Planar Nano-Positioning System

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International Conference on Manipulation, Automation and Robotics at Small Scales (MARSS)

作者： R. Krishna G. R. Jayanth Department of Mechanical Engineering Indian Institute of Science Bangalore India Departments of Instrumentation and Applied Physics and Mechanical Engineering Indian Institute of Science Bangalore India

ISBN: (数字)9798350376807

ISBN: (纸本)9798350376814

Magnetically actuated nano-positioning systems possess several advantages, including linearity in actuation, large positioning range and the possibility of multi-axis collocated actuation. This paper presents a planar nano-positioning system comprising an array of conductive meanders suspended by conductive compliant elements over a checkerboard of permanent magnets. Two distinct designs are reported, one for one-axis positioning and another for two-axis positioning. Such stages enable achieving high positioning speed and multi-axis in-plane actuation without affecting the achievable actuation gain. Theoretical models are proposed for the estimation of magnetic force and stiffness, and for the dynamic response of the positioner. These models are compared with the results of finite element analysis (FEA). The theoretical stiffnesses are shown to agree with the FEA results to within 2.9% and the natural frequencies are shown to agree to within 8.2%. Finally, a prototype of the single-axis positioner is fabricated and shown to track a commanded waveform of amplitude 200μm with good accuracy and negligible cross-axis motion. It is also shown to track a 50nm staircase signal with 5nm RMS resolution. The experimentally obtained natural frequency, estimated from the step-response, is shown to agree with the FEA results to be within 10.8%.

关键词： Tracking Magnetic resonance imaging Dynamics Prototypes Optical imaging Permanent magnets Finite element analysis

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Field-driven cluster formation in two-dimensional colloidal binary mixtures

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Physical Review E 2023年第4期107卷 044605-044605页

作者： Dingwen Qian Monica Olvera de la Cruz Applied Physics Program Department of Materials Science and Engineering Department of Chemistry and Department of Physic and Astronomy Northwestern University Evanston Illinois 60208 USA

We study size- and charge-asymmetric oppositely charged colloids driven by an external electric field. The large particles are connected by harmonic springs, forming a hexagonal-lattice network, while the small particles are free of bonds and exhibit fluidlike motion. We show that this model exhibits a cluster formation pattern when the external driving force exceeds a critical value. The clustering is accompanied with stable wave packets in vibrational motions of the large particles.

关键词： Transport phenomena Charged colloids

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Alloy-buffer-controlled van der Waals epitaxial growth of aligned tellurene

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Nano Research 2022年第6期15卷 5712-5718页

作者： Cong Wang Chao Xu Xuyun Guo Ning Zhang Jianmin Yan Jiewei Chen Wei Yu Jing-Kai Qin Ye Zhu Lain-Jong Li Yang Chai Department of Applied Physics the Hong Kong Polytechnic UniversityHong Kong 999077China The Hong Kong Polytechnic University Shenzhen Research Institute Shenzhen 518057China School of Materials Science and Engineering Harbin Institute of Technology(Shenzhen)Shenzhen 518055China Department of Mechanical Engineering the University of Hong KongHong Kong 999077China

Group-VI elemental two-dimensional(2D)materials(e.g.,tellurene(Te))have unique crystalline structures and extraordinarily physical ***,it still remains a great challenge to controllably grow 2D Te with good repeatability,uniformity,and highly aligned orientation using vapor growth ***,we design a Cu foil-assisted alloy-buffer-controlled growth method to epitaxially grow aligned single-crystalline 2D Te on an insulating mica *** in-situ formation of Cu-Te alloy plays a key role on 2D Te growth,alleviating the spatial and temporal non-uniformity of precursor in conventional vapor deposition *** transmission electron microscopy(TEM)analysis combined with theoretical calculations,we unveil that the alignment growth of Te in the[110]direction is along the[600]direction of mica,owing to the small lattice mismatch(0.15%)and strong binding *** work presents a method to grow aligned high-quality 2D Te in a controllable manner.

关键词： two-dimensional materials tellurene van der Waals interaction epitaxy growth aligned growth

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Time reflection and refraction in synthetic frequency dimension

Time reflection and refraction in synthetic frequency dimens...

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2023 Conference on Lasers and Electro-Optics, CLEO 2023

作者： Long, Olivia Y. Wang, Kai Dutt, Avik Fan, Shanhui Department of Applied Physics Stanford University StanfordCA94305 United States Ginzton Laboratory Department of Electrical Engineering Stanford University StanfordCA94305 United States Department of Mechanical Engineering University of Maryland College ParkMD20742 United States

We demonstrate that time reflection and refraction can be observed in a two-band model centered around a non-zero reference energy. Our model can be physically implemented as a system of two coupled dynamically-modula... 详细信息

ISBN: (纸本)9781957171258

关键词： Refraction

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IoT-based green-smart photovoltaic system under extreme climatic conditions for sustainable energy development

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Global Energy Interconnection 2024年第6期7卷 836-856页

作者： Yufei Wang Jia-Wei Zhang Kaiji Qiang Runze Han Xing Zhou Chen Song Bin Zhang Chatchai Putson Fouad Belhora Hajjaji Abdelowahed School of Electrical Engineering Xi’an University of TechnologyXi’an 710048P.R.China School of Electrical Engineering Xi'an Jiaotong UniversityXi'an 710049P.R.China Faculty of Printing Packing Engineering and Digital Media TechnologyXi’an University of TechnologyXi’an 710054P.R.China School of Mechanical Electrical and Information EngineeringShandong UniversityWeihai 264209P.R.China Materials Physics Laboratory Department of PhysicsFaculty of SciencePrince of Songkla University(PSU)Songkhla 90112Thailand Laboratory of Engineering Sciences for Energy(LabSIPE) National School of Applied SciencesChouaib Doukkali UniversityEl Jadida 24000Morocco

To realize carbon neutrality,there is an urgent need to develop sustainable,green energy systems(especially solar energy systems)owing to the environmental friendliness of solar energy,given the substantial greenhouse gas emissions from fossil fuel-based power *** it comes to the evolution of intelligent green energy systems,Internet of Things(IoT)-based green-smart photovoltaic(PV)systems have been brought into the spotlight owing to their cutting-edge sensing and data-processing *** review is focused on three critical segments of IoT-based green-smart PV ***,the climatic parameters and sensing technologies for IoT-based PV systems under extreme weather conditions are ***,the methods for processing data from smart sensors are discussed,in order to realize health monitoring of PV systems under extreme environmental ***,the smart materials applied to sensors and the insulation materials used in PV backsheets are susceptible to aging,and these materials and their aging phenomena are highlighted in this *** review also offers new perspectives for optimizing the current international standards for green energy systems using big data from IoT-based smart sensors.

关键词： Photovoltaic systems Extreme climatic conditions Data processing Condition monitoring Smart materials

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Experiments at the JSI TRIGA Research Reactor for Validation of Nuclear Fuel Depletion Calculations

Experiments at the JSI TRIGA Research Reactor for Validation...

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2024 International Conference on physics of Reactors, PHYSOR 2024

作者： Anže, Pungerčič Vladimir, Radulović Alireza, Haghighat Luka, Snoj Reactor Physics Department "Jožef Stefan" Institute Jamova cesta 39 Ljubljana1000 Slovenia Faculty of Mathematics and Physics University of Ljubljana Jadranska ul. 19 Ljubljana1000 Slovenia Nuclear Engineering Program Mechanical Engineering Dept. Virginia Tech 900 N. Glebe Road United States

ISBN: (纸本)9780894487972

Importance of experimental methods at research reactors for validation of depletion calculation is discussed. The validation of fuel burnup and nuclide inventory, calculated with stochastic Serpent-2 and hybrid RAPID code system, is performed at JSI TRIGA research reactor. Three different experimental method for indirect burnup determination are presented. The experiments are simulated using Serpent-2 and RAPID depletion codes. First experiment is the fuel rod reactivity worth experiment, in which seven differently burned rods were inserted in the reactor and change in core reactivity was measured. Each insertion was simulated with both codes and great agreement (within 1σ) is observed for both codes. Core's excess reactivity reduction due to burnup was analyzed on three mixed TRIGA cores. Burnup reactivity coefficient was studied with both codes and accurate predictions of reactivity change were obtained. Finally, depleted nuclide inventory is used to simulate dosimetry experiment. Axial profile of 197Au(n, γ)198Au reaction rates was studied using MCNP, where fresh fuel model was compared to the burned fuel model. Fuel burnup was obtained from Serpent-2 and RAPID. The results indicate a 6 % better agreement when Serpent-2 and RAPID's burnup is used. All three experiments indicate a method on how research reactor can be used to in-directly determine and validate nuclear fuel burnup without the use of destructive methods. © 2024 AMERICAN NUCLEAR SOCIETY. All rights reserved.

关键词： Research reactors

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Synchronous-Clock Range-Angle Relative Acoustic Navigation: A Unified Approach to Multi-AUV Localization, Command, Control, and Coordination

Field Robotics

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Field Robotics 2025年 2卷 774-806页

作者： Nicholas R. Rypkema Henrik Schmidt Erin M. Fischell Applied Ocean Physics & Engineering Woods Hole Oceanographic Institution Woods Hole MA 02543 USA Department of Mechanical Engineering Massachusetts Institute of Technology Cambridge MA 02139 USA

This paper presents a scalable acoustic navigation approach for the unified command, control, and coordination of multiple autonomous underwater vehicles (AUVs). Existing multi-AUV operations typically achieve coordination manually by programming individual vehicles on the surface via radio communications, which becomes impractical with large vehicle numbers; or they require bi-directional intervehicle acoustic communications to achieve limited coordination when submerged, with limited scalability due to the physical properties of the acoustic channel. Our approach utilizes a single, periodically broadcasting beacon acting as a navigation reference for the group of AUVs, each of which carries a chip-scale atomic clock and fixed ultrashort baseline array of acoustic receivers. One-way travel-time from synchronized clocks and time-delays between signals received by each array element allow any number of vehicles within receive distance to determine range, angle, and thus determine their relative position to the beacon. The operator can command different vehicle behaviors by selecting between broadcast signals from a predetermined set, while coordination between AUVs is achieved without intervehicle communication by defining individual vehicle behaviors within the context of the group. Vehicle behaviors are designed within a beacon-centric moving frame of reference, allowing the operator to control the absolute position of the AUV group by repositioning the navigation beacon to survey the area of interest. Multiple deployments with a fleet of three miniature, low-cost SandShark AUVs performing closed-loop acoustic navigation in real-time provide experimental results validated against a secondary long-baseline positioning system, demonstrating the capabilities and robustness of our approach with real-world data.

关键词： Acoustics Navigation Robot sensing systems Location awareness Sea surface Robot kinematics Ocean temperature Radio navigation Command and control systems Sea measurements

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mechanically interlocked two-dimensional polymers

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Journal of Bio-X Research 2025年第6731期387卷 264-269页

作者： Bardot, Madison I. Weyhrich, Cody W. Shi, Zixiao Traxler, Michael Stern, Charlotte L. Cui, Jinlei Muller, David A. Becker, Matthew L. Dichtel, William R. Department of Chemistry Northwestern University Evanston IL United States Department of Chemistry Duke University Durham NC United States Department of Chemistry and Chemical Biology Cornell University Ithaca NY United States School of Applied and Engineering Physics and Kavli Institute at Cornell for Nanoscale Science Cornell University Ithaca NY United States Thomas Lord Department of Mechanical Engineering and Materials Science Department of Biomedical Engineering Department of Orthopedic Surgery Duke University Durham NC United States

mechanical bonds arise between molecules that contain interlocked subunits, such as one macrocycle threaded through another. Within polymers, these linkages will confer distinctive mechanical properties and other emergent behaviors, but polymerizations that form mechanical bonds efficiently and use simple monomeric building blocks are rare. In this work, we introduce a solid-state polymerization in which one monomer infiltrates crystals of another to form a macrocycle and mechanical bond at each repeat unit of a two-dimensional (2D) polymer. This mechanically interlocked 2D polymer is formed as a layered solid that is readily exfoliated in common organic solvents, enabling spectroscopic characterization and atomic-resolution imaging using advanced electron microscopy techniques. The 2D mechanically interlocked polymer is easily prepared on multigram scales, which, along with its solution processibility, enables the facile fabrication of composite fibers with Ultem that exhibit enhanced stiffness and strength. © 2025 the authors,

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