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arXiv 2023年

作者： Li, Fei Nie, Hao Zhao, Yu Zhao, Zhihe Huo, Juntao Shen, Hongxian Jiang, Sida Chen, Renjie Yan, Aru Cheong, S.-W. Xia, Weixing Zhang, Lunyong Sun, Jianfei School of Materials Science and Engineering Harbin Institute of Technology Harbin150001 China CISRI NIMTE Joint Innovation Center for Rare Earth Permanent Magnets Ningbo Institute of Material Technology and Engineering Chinese Academy of Science Ningbo315201 China National Key Laboratory of Precision Hot Processing of Metals Harbin Institute of Technology Harbin150001 China Key Laboratory of Magnetic Materials and Devices Ningbo Institute of Material Technology and Engineering CAS Ningbo315201 China Space Environment Simulation Research Infrastructure Harbin Institute of Technology Harbin150001 China Rutgers Center for Emergent Materials Department of Physics and Astronomy Rutgers University 136 Frelinghuysen Rd PiscatawayNJ United States

Magnetic skyrmions offer promising prospects for constructing future energy-efficient and high-density information technology, leading to extensive explorations of new skyrmionic materials recently. The topological Hall effect has been widely adopted as a distinctive marker of skyrmion emergence. Alternately, here we propose a novel signature of skyrmion state by quantitatively investigating the magnetoresistance (MR) induced by skyrmionic bubbles in CeMn2Ge2. An intriguing finding was revealed: the anomalous MR measured at different temperatures can be normalized into a single curve, regardless of sample thickness. This behavior can be accurately reproduced by the recent chiral spin textures MR model. Further analysis of the MR anomaly allowed us to quantitatively examine the effective magnetic fields of various scattering channels. Remarkably, the analyses, combined with the Lorentz transmission electronic microscopy results, indicate that the in-plane scattering channel with triplet exchange interactions predominantly governs the magnetotransport in the Bloch-type skyrmionic bubble state. Our results not only provide insights into the quantum correction on MR induced by skyrmionic bubble phase, but also present an electrical probing method for studying chiral spin texture formation, evolution and their topological properties, which opens up exciting possibilities for identifying new skyrmionic materials and advancing the methodology for studying chiral spin textures. Copyright © 2023, The Authors. All rights reserved.

关键词： Magnetoresistance

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Comparative Analysis on Few Typical Algorithms of Gesture Recognition for Human-robot Interaction 20

Comparative Analysis on Few Typical Algorithms of Gesture Re...

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4th International Conference on Computer science and Application Engineering, CSAE 2020

作者： Ma, Chao Tan, Qimeng Xu, Chaofan Zhao, Jingyi Wang, Xinyu Sun, Jing Beijing Key Laboratory of Intelligent Space Robotic Systems Technology and Applications Beijing Institute of Spacecraft System Engineering Beijing China School of Instrument Science and Optoelectronic Engineering Beijing Information Science and Technology University Beijing China

ISBN: (纸本)9781450377720

Human-robot interaction (HRI) is considered as one of the key techniques of space intelligence robots. Few typical features of complicated human actions need to be captured and understood accurately by intelligent robot to ensure free communication and interaction between both above in real-time, especially for identifying and tracking hand state. There are four approaches for gesture recognition, including algorithm based on Kinect V2 SDK, model-based particle swarm optimization algorithm (PSO), deep learning algorithm and gesture module based on Baidu AI platform. These have been selected to compare in the form of principle, calculating time, robustness, range, environmental adaptability and correct rate respectively. The comparative results have generalized that both the second and the third algorithm have better performance than other algorithms in the above aspects such as calculating efficiency, robustness, detecting range, external disturbance and correct ratio. Particularly, the second algorithm is not only suitable for close range, but also suitable for multi-view cases. However, the third algorithm can have better performance, but depends on precise network model and weights by introducing lots of positive and negative gesture samples. © 2020 ACM.

关键词： Human robot interaction

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Direct-Current, Long-Lasting and Highly Efficient Electret/Triboelectric Energy Harvesting from Ultra-Low-Frequency Motions Using Toothed Clutch Mechanism

SSRN

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SSRN 2022年

作者： Tao, Kai Zhao, Zhe Mao, Xinhui Shen, Weihe Qiu, Changquan Qi, Huan Ye, Tao Zhang, Xingxu Wu, Jin Fan, Kangqi Chang, Honglong Yuan, Weizheng Ministry of Education Key Laboratory of Micro and Nano Systems for Aerospace Northwestern Polytechnical University Xi’an710072 China Science and Technology on Space Physics Laboratory China Academy of Launch Vehicle Technology Beijing100076 China Beijing Institute of Astronautical Systems Engineering China Academy of Launch Vehicle Technology Beijing100076 China State Key Laboratory of Optoelectronic Materials and Technologies Key Laboratory of Display Material and Technology School of Electronics and Information Technology Sun Yat-sen University Guangzhou510275 China School of Mechano-Electronic Engineering Xidian University Xi’an710071 China

Generally, most wearable energy harvesters generate only a small amount of electrical energy from the low-frequency motions of human body and immediately stop working when the activity ends, resulting in low energy extraction efficiency. Here, we propose an electret rotatory energy harvester (e-REH) with a mechanical tooth-clutch transmission system, converting the ultra-low-frequency irregular human motion ( © 2022, The Authors. All rights reserved.

关键词： Nanogenerators

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Using simulation and Digital Twins to Innovate: Are we Getting Smarter?

Using Simulation and Digital Twins to Innovate: Are we Getti...

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2021 Winter simulation Conference, WSC 2021

作者： Taylor, Simon J E Johansson, Bjorn Jeon, Sumin Lee, Loo Hay Lendermann, Peter Shao, Guodong Brunel University London Modelling Simulation Group Department of Computer Science Uxbridge United Kingdom Chalmers University of Technology Department of Industrial and Materials Science Gothenburg41296 Sweden Digital Industries Customer Services Siemens Pte Ltd Singapore National University of Singapore Department of Industrial Systems Engineering Management Singapore D-SIMLAB Technologies Pte Ltd Singapore National Institute of Standards and Technology Engineering Laboratory GaithersburgMD20899 United States

ISBN: (纸本)9781665433112

Digital Twins have recently emerged as a major new area of innovation. Digital Twins are often found at the core of 'smart' solutions that have also emerged as major areas of innovation. Modeling and simulation (MS) approaches create a model of a real-world system that is linked to data sources and is used to simulate and predict the behavior of its real-world counterpart. On the face of it Digital Twins and MS appear to be similar, if not the same. Is this actually the case? Are the two fields really separate or is Digital Twin research re-inventing the 'MS wheel'? To investigate these relationships, in this panel we will explore some contemporary innovations with Digital Twins and discuss whether or not Digital Twins is a contemporary 'refresh' or 'rebranding' of MS or if there are exciting new synergies. © 2021 IEEE.

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Research on obstacle detection and path planning based on visual navigation for mobile robot 4

Research on obstacle detection and path planning based on vi...

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2020 4th International Conference on Electrical, Mechanical and Computer Engineering, ICEMCE 2020

作者： Zheng, Yixiao Yan, Bixi Ma, Chao Wang, Xinyu Xue, Haoyang School of Instrument Science and Optoelectronic Engineering Beijing Information Science and Technology University Beijing China Beijing Key Laboratory of Intelligent Space Robotic Systems Technology and Applications Beijing Institute of Spacecraft System Engineering Beijing China

Both obstacle and path planning are of significance for autonomous visual navigation of a mobile robot which is able to realize free movement and obstacle avoidance. In this paper, a scheme of obstacle detection which is based on binocular vision to identify obstacles is constructed and it is combined with improved A* algorithm for obstacle avoidance motion for mobile robot platform. First, a binocular vision system to detect the robot's perception of the environment is used and the visual information is obtained. Then a Gaussian filter is used to reduce the noise in the image, and the grayscale image is obtained through the binocular vision system. The gray scale map is matched with SAD (Sum of Absolute Differences) in order to obtain the disparity image with comparison. Second, the location information of the obstacle is extracted through the environmental depth information contained in the disparity image, and the improved A* algorithm is used as the path planning algorithm in this paper, which can modify the path of the planning error. Furthermore, the detection experiment of the robot visual obstacle avoidance system was established and the optimal path was obtained. The examples show that, the obstacle avoidance system can complete the task of obstacle detection and give a better path for the mobile robot. © 2020 Journal of Physics: Conference Series.

关键词： Mobile robots

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Intercalibration of the reflective solar bands of MODIS and MISR instruments on the Terra platform 26

Intercalibration of the reflective solar bands of MODIS and ...

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Earth Observing systems XXVI 2021

作者： Angal, Amit Bruegge, Carol Xiong, Xiaoxiong Wu, Aisheng Science Systems and Applications Inc. 10210 Greenbelt Rd LanhamMD20706 United States NASA Jet Propulsion Laboratory California Institute of Technology PasadenaCA91109 United States Sciences and Exploration Directorate NASA Goddard Space Flight Center GreenbeltMD United States

ISBN: (数字)9781510644977

ISBN: (纸本)9781510644960

The multispectral imaging sensors on the Terra platform have been operating for over two decades facilitating a variety of scientific applications. The MODIS sensor provides the largest spectral coverage of 0.41 to 14.2 µm, acquiring data at three different spatial resolutions, 250 m, 500 m, and 1 km. The MISR instrument views the Earth using nine discrete cameras pointed at fixed angles including viewing the nadir direction at a spatial resolution of 275 m and covering a wavelength range from 0.44 to 0.86 µm. Being on the same platform, the two sensors complement each other in terms of spatial coverage (and target viewing geometry) and facilitate synergistic applications using multispectral data. A consistent radiometric calibration between these sensors is a prerequisite for creating high quality science products from their observations. Both instruments underwent intensive prelaunch characterization, with calibration monitored on-orbit using their onboard calibrators. In this paper, we perform a calibration inter-comparison of the spectrally matching bands of the two instruments using vicarious techniques. Vicarious techniques include multiyear simultaneous views of the North African desert, North Atlantic Ocean and Dome Concordia, thereby covering the different parts of the dynamic range. Also included in this work are the near-simultaneous top-of-atmosphere (TOA) reflectance measurements from Railroad Valley, USA, as provided by the RadCalNet (converted to TOA), that are used as a calibration reference to compare the on-orbit observations between MODIS and MISR. © 2021 SPIE.

关键词： Calibration

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JIRAM Observations of Volcanic Flux on Io: Distribution and Comparison to Tidal Heat Flow Models

arXiv

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arXiv 2023年

作者： Pettine, M. Imbeah, S. Rathbun, J. Hayes, A. Lopes-Gautier, R. Mura, A. Tosi, F. Zambon, F. Bertolino, S. Lopes, R.M.C. Cornell University IthacaNY United States Malin Space Science Systems San DiegoCA United States Planetary Science Institute TucsonAZ United States Jet Propulsion Laboratory California Institute of Technology PasadenaCA United States INAF‐IAPS Istituto Nazionale di Astrofisica Istituto di Astrofisica e Planetologia Spaziali Rome Italy

Juno has allowed clear, high‐resolution imaging of Io's polar volcanoes using the Jovian Infrared Auroral Mapper (JIRAM) instrument. We have used data from JIRAM's M‐band (4.78 μm) imager from 11 Juno orbits to construct a global map of volcanic flux. This map provides short‐term insight into the spatial distribution of volcanoes and the ways in which high‐ and low‐latitude volcanoes differ. Using spherical harmonic analysis, we quantitatively compare our volcanic flux map to the surface heat flow distribution expected from models of Io's tidal heat deposition (summarized in de Kleer, Park, et al. (2019, https://***/10. 26206/d4wc‐6v82). Our observations confirm previously detected systems of bright volcanoes at high latitudes. Our study finds that both poles are comparably active and that the observed flux distribution is inconsistent with an asthenospheric heating model, although the south pole is viewed too infrequently to establish reliable trends. Plain Language Summary Our study uses data from an infrared camera on Juno called the Jovian Infrared Auroral Mapper (JIRAM) to image Io, the innermost Galilean moon of Jupiter. Io is the most volcanically active body in the Solar System. Io's volcanoes are powered by both the extreme tides from Jupiter and the gravitational interactions between it and Jupiter's other moons. These tides generate friction inside Io. simulations of Io's interior suggest that, depending on how deep that friction is being generated, the surface heat flow will be higher in certain areas (de Kleer, Park, et al., 2019, https://***/10.26206/d4wc‐6v82). Using JIRAM, we have mapped where volcanoes are producing the most power and compared that to where we expect higher heat flow from the interior models. Our map doesn't agree with any of these models very well. JIRAM observed more volcanic activity at the poles than we expected to see based on previous observations. However, since the south pole was only observed twice, it's possible th

关键词： Volcanoes

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Directional polarization modulation for secure dual-polarized satellite communication

Directional polarization modulation for secure dual-polarize...

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2019 International Conference on Communications, Information System, and Computer Engineering, CISCE 2019

作者： Luo, Zhangkai Pei, Zhongmin Zou, Bo Science and Technology on Complex Electronic System Simulation Laboratory Space Engineering University Beijing China

ISBN: (纸本)9781728136813

This paper proposes a directional polarization modulation method to enhance the transmission security in dual-polarized satellite communications. Indeed, two components of the polarized signal are respectively transmitted by two orthogonally polarized beams, which are formed by a dual-polarized array. Subsequently, a deviation angle is designed, which is used to determine the difference between the desired direction and the direction of the polarized beams. With a positive deviation angle, two polarized beams point to different directions. In this manner, only in the desired direction that two beam gains equal to each other, the polarized signals can be demodulated accurately, while the constellation is distorted in undesired directions, which makes it difficult to recover the information and, thus the transmission security is enhanced. Theoretical analysis and simulation results demonstrate the security performance of the proposed method. © 2019 IEEE.

关键词： Satellites

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Improving the Automated Coronal Jet Identification with U-NET

arXiv

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arXiv 2024年

作者： Liu, Jiajia Ji, Chunyu Wang, Yimin Soós, Szabolcs Jiang, Ye Erdélyi, Robertus Korsós, M.B. Wang, Yuming Deep Space Exploration Lab School of Earth and Space Sciences University of Science and Technology of China Hefei230026 China CAS Key Laboratory of Geospace Environment CAS Center for Excellence in Comparative Planetology Mengcheng National Geophysical Observatory University of Science and Technology of China Hefei230026 China School of Data Science Qingdao University of Science and Technology Qingdao266100 China Department of Astronomy Eötvös Loránd University Pázmány P. sétány 1/A BudapestH-1117 Hungary Petőfi tér 3. GyulaH-5700 Hungary School of Information Science and Technology Qingdao University of Science and Technology Qingdao266100 China School of Mathematics and Statistics The University of Sheffield SheffieldS3 7RH United Kingdom University of Sheffield Department of Automatic Control and Systems Engineering Amy Johnson Building Portabello Street SheffieldS1 3JD United Kingdom

Coronal jets are one of the most common eruptive activities in the solar atmosphere. They are related to rich physics processes, including but not limited to magnetic reconnection, flaring, instabilities, and plasma heating. Automated identification of off-limb coronal jets has been difficult due to their abundant nature, complex appearance, and relatively small size compared to other features in the corona. In this paper, we present an automated coronal jet identification algorithm (AJIA) that utilizes true and fake jets previously detected by a laborious semi-automated jet detection algorithm (SAJIA, Liu et al. 2023) as the input of an image segmentation neural network U-NET. It is found that AJIA could achieve a much higher (0.81) detecting precision than SAJIA (0.34), meanwhile giving the possibility of whether each pixel in an input image belongs to a jet. We demonstrate that with the aid of artificial neural networks, AJIA could enable fast, accurate, and real-time coronal jet identification from SDO/AIA 304 Å observations, which are essential in studying the collective and long-term behavior of coronal jets and their relation with the solar activity cycles. Copyright © 2024, The Authors. All rights reserved.

关键词： Image segmentation

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Observations of high definition symmetric quasi-periodic oscillations in the mid-latitude ionosphere with LOFAR

arXiv

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arXiv 2023年

作者： Trigg, Hannah Dorrian, Gareth Boyde, Ben Wood, Alan Fallows, Richard A. Mevius, Maaijke SERENE Group Electronic Electrical and Systems Engineering University of Birmingham United Kingdom RAL Space United Kingdom Research and Innovation Science & Technology Facilities Council Rutherford Appleton Laboratory Harwell Campus Oxfordshire United Kingdom ASTRON - The Netherlands Institute for Radio Astronomy Oude Hoogeveensedijk 4 Dwingeloo7991 PD Netherlands

We present broadband ionospheric scintillation observations of highly defined symmetric quasi-periodic oscillations (QPO: Maruyama 1991) caused by plasma structures in the midlatitude ionosphere using the LOw Frequency ARray (LOFAR: van Haarlem et al., 2013). Two case studies are shown, one from 15th. December 2016, and one from 30th. January 2018, in which well-defined main signal fades and secondary diffraction fringing are observed. In particular, the broadband observing capabilities of LOFAR permit us to see considerable frequency dependent behaviour in the QPOs which, to our knowledge, is a new result. We extract some of the clearest examples of scintillation arcs reported in an ionospheric context, from delay-Doppler spectral analysis of these two events. These arcs permit the extraction of propagation velocities for the plasma structures causing the QPOs ranging from 50-200 ms-1, depending on the assumed altitude. The spacing between the individual plasma structures ranges between 5-20 km. The periodicities of the main signal fades in each event and, in the case of the 2018 data, co-temporal ionosonde data, suggest the propagation of the plasma structures causing the QPOs is in the E-region. Each of the two events is accurately reproduced using a Gaussian perturbation phase screen model. Individual signal fades and enhancements were modelled using small variations in total electron content (TEC) amplitudes of order1 mTECu, demonstrating the sensitivity of LOFAR to very small fluctuations in ionospheric plasma density. To our knowledge these results are among the most detailed observations and modelling of QPOs in the literature. © 2023, CC BY.

关键词： Scintillation

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