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A Normal Distribution Transform-Based Radar Odometry Designed For Scanning and Automotive Radars

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arXiv 2021年

作者： Kung, Pou-Chun Wang, Chieh-Chih Lin, Wen-Chieh Graduate Degree Program of Robotics National Chiao Tung University Hsinchu Taiwan Department of Electrical and Computer Engineering National Chiao Tung University The Mechanical and Mechatronics Systems Research Laboratories Industrial Technology Research Institute Hsinchu Taiwan Department of Computer Science National Chiao Tung University Hsinchu Taiwan

Existing radar sensors can be classified into automotive and scanning radars. While most radar odometry (RO) methods are only designed for a specific type of radar, our RO method adapts to both scanning and automotive radars. Our RO is simple yet effective, where the pipeline consists of thresholding, probabilistic submap building, and an NDT-based radar scan matching. The proposed RO has been tested on two public radar datasets: the Oxford Radar RobotCar dataset and the nuScenes dataset, which provide scanning and automotive radar data respectively. The results show that our approach surpasses state-of-the-art RO using either automotive or scanning radar by reducing translational error by 51% and 30%, respectively, and rotational error by 17% and 29%, respectively. Besides, we show that our RO achieves centimeter-level accuracy as lidar odometry, and automotive and scanning RO have similar accuracy. Copyright © 2021, The Authors. All rights reserved.

关键词： Optical radar

Energy Dissipation of Ship Structures subjected to Impact Loading: A Study Case in Side Collision

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Procedia Structural Integrity 2020年 27卷 171-178页

作者： Aditya Rio Prabowo Haris Nubli Jung Min Sohn Department of Mechanical Engineering Universitas Sebelas Maret Surakarta 57126 Indonesia Interdisciplinary Program of Marine Convergence Design Pukyong National University Busan 48513 South Korea Department of Naval Architecture and Marine Systems Engineering Pukyong National University Busan 48513 South Korea

The main goal of the present paper is to study the energy dissipation characteristic as the influence of parameters in the event of ship collisions. The review is conducted on accident case between Roll on-Roll off (Ro-Ro) Marisa Nusantara with Reefer Qi Hang at Sunda Strait, Indonesia May 3rd, 2014, as reference. It was later modeled and analyzed by nonlinear simulations finite element (FE) method was presented to be used as a reference to get the verified model. This collaboration study is considered as a good reference because it used real accident damage to compare the numerical results. The result in collision energy from the virtual simulation was later verified with the calculation result of the empirical formula. In the extended study, the collision region and material model are selected as influenced parameters to design collision scenarios. The characteristic of collision energy from these scenarios will be discussed. In the same section, the damage pattern is observed and reviewed to find the relation between several parameters to calculation results. It was shown that the influence of region and location of target points contributed significantly to energy dissipation. In contrast, the key finding in material properties is that when Young’s modulus between materials was the same and the difference of yield strength of materials was not significant, then other material properties contributed to the result.

关键词： Accidental loads ship collision Ro-Ro vessel double-hull structures crashworthiness energy dissipation

Charge and Energy Transfer Dynamics of Hybridized Exciton-Polaritons in 2D Halide Perovskites

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arXiv 2023年

作者： Anantharaman, Surendra B. Lynch, Jason Stevens, Christopher E. Munley, Christopher Li, Chentao Hou, Jin Zhang, Hao Torma, Andrew Darlington, Thomas Coen, Francis Li, Kevin Majumdar, Arka Schuck, P. James Mohite, Aditya Harutyunyan, Hayk Hendrickson, Joshua R. Jariwala, Deep Department of Electrical and Systems Engineering University of Pennsylvania PhiladelphiaPA19104 United States KBR Inc. BeavercreekOH45431 United States Air Force Research Laboratory Sensors Directorate Wright-Patterson Air Force Base OH45433 United States Department of Physics University of Washington SeattleWA98195 United States Department of Physics Emory University AtlantaGA30322 United States Department of Chemical and Biomolecular Engineering Rice University HoustonTX77005 United States Department of Materials Science and Nanoengineering Rice University HoustonTX77005 United States Applied Physics Program Smalley‐Curl Institute Rice University HoustonTX77005 United States Department of Mechanical Engineering Columbia University New YorkNY10027 United States Department of Electrical and Computer Engineering University of Washington SeattleWA98195 United States

Excitons, bound electron-hole pairs, in Two-Dimensional Hybrid Organic Inorganic Perovskites (2D HOIPs) are capable of forming hybrid light-matter states known as exciton-polaritons (E-Ps) when the excitonic medium is confined in an optical cavity. In the case of 2D HOIPs, they can self-hybridize into E-Ps at specific thicknesses of the HOIP crystals that form a resonant optical cavity with the excitons. However, the fundamental properties of these self-hybridized E-Ps in 2D HOIPs, including their role in ultrafast energy and/or charge transfer at interfaces, remain unclear. Here, we demonstrate that > 0.5 µm thick 2D HOIP crystals on Au substrates are capable of supporting multiple-orders of self-hybridized E-P modes. These E-Ps have high Q factors (> 100) and modulate the optical dispersion for the crystal to enhance sub-gap absorption and emission. Through varying excitation energy and ultrafast measurements, we also confirm energy transfer from higher energy upper E-Ps to lower energy, lower E-Ps. Finally, we also demonstrate that E-Ps are capable of charge transport and transfer at interfaces. Our findings provide new insights into charge and energy transfer in E-Ps opening new opportunities towards their manipulation for polaritonic devices. © 2023, CC BY.

关键词： Charge transfer

Correction: Optimization of misfit calcium cobaltite oxygen electrodes for solid oxide fuel cells through electrospinning processing

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Journal of Materials Chemistry A 2024年第40期12卷 27777-27777页

作者： Allan J. M. Araújo Itzhak I. Maor Laura I. V. Holz Meirav Mann-Lahav Vadim Beilin Armin Feldhoff Gideon S. Grader Francisco J. A. Loureiro Department of Mechanical Engineering TEMA – Centre for Mechanical Technology and Automation University of Aveiro 3810-193 Aveiro Portugal LASI – Intelligent Systems Associate Laboratory Guimarães Portugal Wolfson Department of Chemical Engineering Technion – Israel Institute of Technology 3200003 Haifa Israel Institute of Physical Chemistry and Electrochemistry Leibniz University Hannover 30167 Hannover Germany The Nancy & Stephan Grand Technion Energy Program (GTEP) Technion – Israel Institute of Technology 3200003 Haifa Israel

Correction for ‘Optimization of misfit calcium cobaltite oxygen electrodes for solid oxide fuel cells through electrospinning processing’ by Allan J. M. Araújo et al., J. Mater. Chem. A, 2024, https://***/10.10...

Correction for ‘Optimization of misfit calcium cobaltite oxygen electrodes for solid oxide fuel cells through electrospinning processing’ by Allan J. M. Araújo et al., J. Mater. Chem. A, 2024, https://***/10.1039/D4TA04085F.

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Regression Model for Optimum Solar Collectors’ Tilt Angles in Libya

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Regression Model for Optimum Solar Collectors’ Tilt Angles ...

Renewable Energy & Sustainability (ieCRES), International engineering Conference on

作者： Yasser F. Nassar Hala J. El- Khozondar Nasser M. Abouhmod Ahmed A. Abubaker Abdussalam A. Ahmed Abdulgader Alsharif Mohamed M. Khaleel Mohamed Elnaggar Rifa J. El-Khozondar Mechancal & Renewable energy. Eng. Dept. Wadi Alshatti University Brack-Libya Electrical Eng. and Smart Systems Dept. The Islamic University of Gaza Gaza Palestine Electrical and Electronic Eng. Dept. Eng. Faculty Wadi Alshatti University Brack-Libya Mechanical Eng. Dept. Bani Waleed University Bani Waleed Libya Faculty of Engineering Universiti Teknologi Malaysia (UTM) Johor Malaysia Dept. of Electrical and Electronic Eng. Karabu University Karabuk Turkey Engineering Program Department Palestine Technical College – Deir ElBalah Deir El-Balah Palestine Physics Departments Faculty of Science Gaza Al-Aqsa University Gaza Palestine

The present study presents a regression function for optimum tilt angle for fixed mode flat-plate solar harvesters suitable for different locations in Libya, sky conditions and albedo values. The research based on 14 years -15 minutes time series solar irradiation components which provided by Solargis database platform for 24 different locations in Libya, based on the contract signed between the Solargis Company and Wadi AlShatti University. Several transposition models are applied - corresponding to each location - for estimating the tilted global solar irradiance components according to recommendation of a local recent study. The proposed model corrects the optimum tilt angle by involving the three components of the solar irradiation: direct beam, sky-diffused and ground reflected solar irradiances. The results proved the applicability and reliability of the obtained regression model. In addition, results showed the high potential of the proposed model for use in engineering design, eco-energetic analysis and optimum design processes.

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Effects of carbon nanofiber z-threads on the longitudinal compressive strength of unidirectional CFRP laminates

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Effects of carbon nanofiber z-threads on the longitudinal co...

SAMPE 2019 Conference and Exhibition

作者： Kirmse, Sebastian Kim, Keonhyeong Ranabhat, Bikash Hsiao, Kuang-Ting College of Engineering University of South Alabama MobileAL36688 United States Systems Engineering Program University of South Alabama MobileAL36688 United States Department of Mechanical Engineering University of South Alabama MobileAL36688 United States

ISBN: (纸本)9781934551301

In this study, unidirectional carbon fiber prepregs that contain long carbon nanofiber (CNF) z-threads as a through-thickness (z-directional) reinforcement were manufactured. The CNF z-threads are long enough to thread through multiple carbon fiber (CF) arrays, which creates a multi-scale CNF/CF/resin-composite. The CNF z-threaded prepregs were manufactured using an electric-field aligned flow-transferring process. It was hypothesized that the CNF z-threads with the zig-zag threading pattern reinforces the interlaminar and intralaminar regions of the CFRP laminate thus improve the compressive strength by reducing the chance of carbon fiber buckling. Compressive testing was performed per modified version of ASTM D695 (i.e., SACMA SRM 1R-94) to evaluate the compressive strength of the CNF z-threaded CFRP (ZT-CFRP) laminates. The samples were manufactured using AS4 carbon fibers, EPON 862/Epikure-W resin and a 1wt% CNF content. ZT-CFRP testing results were compared with unaligned CNF-modified CFRP (UA-CFRP) and unmodified CFRP samples to investigate the impact of the CNF z-threads on the compressive strength. Results showed an increase of ~15% for the compressive strength of ZT-CFRPs, whereas the UA-CFRPs experienced a decrease of ~8% when compared to unmodified CFRPs. It was concluded that CNF/carbon fiber interlocking stops and delays crack growth, and helps to stabilize carbon fibers from further buckling. Copyright 2019 by Sebastian Kirmse et al. Published by Society for the Advancement of Material and Process engineering with permission.

关键词： Carbon nanofibers

Unifying femtosecond and picosecond single-pulse magnetic switching in Gd-Fe-Co

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Physical Review B 2021年第10期103卷 104422-104422页

作者： F. Jakobs T. A. Ostler C.-H. Lambert Y. Yang S. Salahuddin R. B. Wilson J. Gorchon J. Bokor U. Atxitia Dahlem Center for Complex Quantum Systems and Fachbereich Physik Freie Universität Berlin 14195 Berlin Germany Département de Physique Universitè de Liége (B5) B-4000 Liége Belgium College of Business Technology and Engineering Sheffield Hallam University Howard Street Sheffield S1 1WB United Kingdom Department of Electrical Engineering and Computer Sciences University of California Berkeley California 94720 USA Department of Materials Science and Engineering University of California Berkeley California 94720 USA Lawrence Berkeley National Laboratory 1 Cyclotron Road Berkeley California 94720 USA Department of Mechanical Engineering and Materials Science and Engineering Program University of California Riverside California 92521 USA

Many questions are still open regarding the physical mechanisms behind the magnetic switching in Gd-Fe-Co alloys by single optical pulses. Phenomenological models suggest a femtosecond scale exchange relaxation between sublattice magnetization as the driving mechanism for switching. The recent observation of thermally induced switching in Gd-Fe-Co by using both several picosecond optical laser pulse as well as electric current pulses has questioned this previous understanding. This has raised the question of whether or not the same switching mechanics are acting at the femtosecond and picosecond scales. In this work, we aim at filling this gap in the understanding of the switching mechanisms behind thermal single-pulse switching. To that end, we have studied experimentally thermal single-pulse switching in Gd-Fe-Co alloys, for a wide range of system parameters, such as composition, laser power, and pulse duration. We provide a quantitative description of the switching dynamics using atomistic spin dynamics methods with excellent agreement between the model and our experiments across a wide range of parameters and timescales, ranging from femtoseconds to picoseconds. Furthermore, we find distinct element-specific damping parameters as a key ingredient for switching with long picosecond pulses and argue that switching with pulse durations as long as 15 ps is possible due to a low damping constant of Gd. Our findings can be easily extended to speed up dynamics in other contexts where ferrimagnetic Gd-Fe-Co alloys have been already demonstrated to show fast and energy-efficient processes, e.g., domain-wall motion in a track and spin-orbit torque switching in spintronics devices.

关键词： Demagnetization Magnetic interactions Magnetic order Magnetism Spin dynamics Ultrafast magnetic effects

Radar Occupancy Prediction with Lidar Supervision while Preserving Long-Range Sensing and Penetrating Capabilities

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arXiv 2021年

作者： Kung, Pou-Chun Wang, Chieh-Chih Lin, Wen-Chieh The Graduate Degree Program of Robotics National Yang Ming Chiao Tung University Hsinchu Taiwan The Department of Electrical and Computer Engineering National Yang Ming Chiao Tung University Taiwan The Mechanical and Mechatronics Systems Research Laboratories Industrial Technology Research Institute Hsinchu Taiwan The Department of Computer Science National Yang Ming Chiao Tung University Hsinchu Taiwan

Radar shows great potential for autonomous driving by accomplishing long-range sensing under diverse weather conditions. But radar is also a particularly challenging sensing modality due to the radar noises. Recent works have made enormous progress in classifying free and occupied spaces in radar images by leveraging lidar label supervision. However, there are still several unsolved issues. Firstly, the sensing distance of the results is limited by the sensing range of lidar. Secondly, the performance of the results is degenerated by lidar due to the physical sensing discrepancies between the two sensors. For example, some objects visible to lidar are invisible to radar, and some objects occluded in lidar scans are visible in radar images because of the radar's penetrating capability. These sensing differences cause false positive and penetrating capability degeneration, respectively. In this paper, we propose training data preprocessing and polar sliding window inference to solve the issues. The data preprocessing aims to reduce the effect caused by radar-invisible measurements in lidar scans. The polar sliding window inference aims to solve the limited sensing range issue by applying a near-range trained network to the long-range region. Instead of using common Cartesian representation, we propose to use polar representation to reduce the shape dissimilarity between long-range and near-range data. We find that extending a near-range trained network to long-range region inference in the polar space has 4.2 times better IoU than in Cartesian space. Besides, the polar sliding window inference can preserve the radar penetrating capability by changing the viewpoint of the inference region, which makes some occluded measurements seem non-occluded for a pretrained network. Copyright © 2021, The Authors. All rights reserved.

关键词： Optical radar

An efficient two-dimensional heat transfer model for building envelopes

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arXiv 2021年

作者： Berger, Julien Gasparin, Suelen Mazuroski, Walter Mendes, Nathan UMR 7356 CNRS La Rochelle Université CNRS La Rochelle17000 France Univ. Savoie Mont Blanc LOCIE Chambéry73000 France Thermal Systems Laboratory Mechanical Engineering Graduate Program Pontifícia Universidade Católica do Paraná Rua Imaculada Conceição 1155 CuritibaCEP: 80215-901 Brazil

A two-dimensional model is proposed for energy efficiency assessment through the simulation of heat transfer in building envelopes, considering the influence of the surrounding environment. The model is based on the Du Fort–Frankel approach that provides an explicit scheme with a relaxed stability condition. The model is first validated using an analytical solution and then compared to three other standard schemes. Results show that the proposed model offers a good compromise in terms of high accuracy and reduced computational efforts. Then, a more complex case study is investigated, considering non-uniform shading effects due to the neighboring buildings. In addition, the surface heat transfer coefficient varies with wind velocity and height, which imposes an addition non-uniform boundary condition. After showing the reliability of the model prediction, a comparison over almost 120 cities in France is carried out between the two- and the one-dimensional approaches of the current building simulation programs. Important discrepancies are observed for regions with high magnitudes of solar radiation and wind velocity. Last, a sensitivity analysis is carried out using a derivative-based approach. It enables to assess the variability of the solution according to the modeling of the two-dimensional boundary conditions. Moreover, the proposed model computes efficiently the solution and its sensitivity to the modeling of the urban environment. © 2021, CC BY-NC-SA.

关键词： Wind