Article
Multidisciplinary Sciences
S. D. Bale, J. F. Drake, M. D. McManus, M. I. Desai, S. T. Badman, D. E. Larson, M. Swisdak, T. S. Horbury, N. E. Raouafi, T. Phan, M. Velli, D. J. McComas, C. M. S. Cohen, D. Mitchell, O. Panasenco, J. C. Kasper
Summary: The fast solar wind that fills the heliosphere originates from coronal holes on the Sun and is believed to be accelerated by magnetic reconnection mechanisms such as wave heating and interchange reconnection. Measurements from the Parker Solar Probe provide strong evidence for the interchange reconnection mechanism, showing imprints of supergranulation structure in the solar wind and the presence of magnetic switchbacks and bursty wind streams. Computer simulations support these observations and suggest that the reconnection is collisionless and drives the fast wind through both plasma pressure and radial Alfvenic flow bursts.
Article
Engineering, Electrical & Electronic
Sagar Gaur, Yingjie Tang, Matthew A. A. Franchek, Karolos Grigoriadis, Jay Pickett
Summary: A new advanced two-dimensional hybrid analytical model is developed to analyze the performance of a segmented magnet linear actuator (MLA) comprised of surface permanent magnets (PM). The model takes into account the correction for magnetic flux effects and is validated by computational modeling. It is found that using a non-uniform PM segmentation design improves the performance of the MLA compared to conventional radially magnetized MLA and uniform segmented Halbach Array based MLA.
Article
Geosciences, Multidisciplinary
K. Jiang, S. Y. Huang, Z. G. Yuan, X. H. Deng, Y. Y. Wei, Q. Y. Xiong, S. B. Xu, J. Zhang, Z. H. Zhang, R. T. Lin, L. Yu
Summary: A statistical analysis was performed on current density, energy conversion, and electron acceleration in primary and secondary flux ropes, showing differences and patterns that can enhance understanding of their roles in magnetotail dynamics.
GEOPHYSICAL RESEARCH LETTERS
(2021)
Article
Engineering, Electrical & Electronic
Yuanzhi Zhang, Dawei Li, Peng Yan, Xiang Ren, Ronghai Qu, Jimin Ma
Summary: This article proposes a novel claw-pole PMV (CPPMV) machine and investigates its working principle. The CPPMV machine is compared with other machines in terms of their electromagnetic performances using equivalent circuit analysis and FEM. The results show that the claw-pole structure can enhance the magnetic flux modulation effects and increase the machine torque density.
IEEE JOURNAL OF EMERGING AND SELECTED TOPICS IN POWER ELECTRONICS
(2022)
Article
Chemistry, Multidisciplinary
Yaojung Shiao, Manichandra Bollepelly
Summary: A magnetorheological brake (MRB) utilizes the shearing effect of MR fluid in a magnetic field to create resistance between moving surfaces. This research focused on studying the effect of pole head geometry in a multipole dual disc compact MR brake and found that hexagonal and elliptical pole heads achieved better magnetic field area, intensity distribution, and flux lines piercing through the MR fluid. The performance of the brake was improved, with a 3.88% increase in braking torque.
APPLIED SCIENCES-BASEL
(2023)
Article
Astronomy & Astrophysics
Yi Xing, Zhongxiang Wang, Xiao Zhang, Yang Chen
Summary: We report a possible gamma-ray enhancement event that lasted for 1.5 yr and showed a factor of 3.6 flux increase mainly in the energy range of 4-100 GeV, accompanied by two 478 GeV photons. This event, observed in Tycho's supernova remnant, reveals the more complicated side of the physical processes that can occur in young supernova remnants.
ASTROPHYSICAL JOURNAL
(2022)
Article
Quantum Science & Technology
A. G. Abdelwahab, S. A. Ghwail, Nasser Metwally, M. H. Mahran, A. -S. F. Obada
Summary: The study discusses the possibility of masking an accelerated two-qubit system using a minimum number of qubits, showing that information can be masked in either entangled local states or product non-local separable states. The efficiency of the masking process is examined by quantifying the fidelity, with results showing that the fidelity of the masked state is maximum at small initial acceleration, while the minimum fidelity is more than 96%.
QUANTUM INFORMATION PROCESSING
(2021)
Review
Astronomy & Astrophysics
O. Khabarova, O. Malandraki, H. Malova, R. Kislov, A. Greco, R. Bruno, O. Pezzi, S. Servidio, Gang Li, W. Matthaeus, J. Le Roux, N. E. Engelbrecht, F. Pecora, L. Zelenyi, V Obridko, V Kuznetsov
Summary: Recent studies in the heliosphere have shifted the focus from a 2D perspective to a more comprehensive understanding of 3D processes, revealing previously unimaginable dynamics through simulations and observations. Current research is centered on exploring plasma structures and their observations in the heliosphere.
SPACE SCIENCE REVIEWS
(2021)
Article
Multidisciplinary Sciences
Yusuke Iguchi, Ruby A. A. Shi, Kunihiro Kihou, Chul-Ho Lee, Mats Barkman, Andrea L. L. Benfenati, Vadim Grinenko, Egor Babaev, Kathryn A. A. Moler
Summary: In this study, it was found that quantum vortices with nonuniversally quantized magnetic flux exist in the superconductor Ba1-xKxFe2As2 (x = 0.77). These vortices enclose a magnetic flux equal to the magnetic flux quantum, but the magnitude of the flux is not universally quantized and varies continuously with temperature.
Article
Engineering, Electrical & Electronic
Byung-Chan Kim, Dong-Woo Kang
Summary: This study introduces a novel consequent pole wound field synchronous machine (CPWFSM) for ISG, which can easily generate high torque at starting with permanent magnet (PM) and produce power in a wide range of operation speeds in generating mode. It has the advantage of using low field current to generate output power at various speed areas compared to existing WFSM structure.
IEEE TRANSACTIONS ON MAGNETICS
(2021)
Article
Astronomy & Astrophysics
Roger B. Scott, Stephen J. Bradshaw, Mark G. Linton
Summary: In this study, the dynamic evolution of a solar wind stream along a newly-opened magnetic flux tube is simulated, and the time-dependent non-equilibrium ionization of oxygen near the reconnection site is calculated. The results show that the interchange reconnection enhances the density, velocity, and ionization ratio of oxygen in the slow solar wind.
ASTROPHYSICAL JOURNAL
(2022)
Article
Engineering, Electrical & Electronic
Abdur Rehman, Byungtaek Kim
Summary: This study focuses on a consequent-pole vernier motor that utilizes low-cost ferrite magnets. The magnetic behavior of this motor is investigated quantitatively using newly proposed magnetic equivalent models. The study reveals that the consequent-pole structure significantly reduces the effective air-gap length, resulting in higher modulation flux density compared to traditional surface permanent magnet vernier machines. The study also demonstrates that the consequent-pole motor exhibits considerable advantages in terms of reluctance torque due to the variation of air-gap length caused by the thick magnet thickness. Experimental results validate the analytical and numerical analyses conducted in the study.
IEEE JOURNAL OF EMERGING AND SELECTED TOPICS IN POWER ELECTRONICS
(2022)
Article
Automation & Control Systems
Jun Luo, Baoquan Kou, Xiaobao Yang, He Zhang, Lu Zhang
Summary: Transverse flux machines can achieve high force density by reducing the pole pitch, but this may lead to motor performance degradation. This article introduces a novel dual-consequent-pole transverse flux linear machine with a dual-PM structure to enhance coil flux linkage and improve force density without increasing volume.
IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS
(2021)
Article
Environmental Sciences
Nikolay G. Granin, Vladimir V. Kozlov, Marc De Batist, Igor B. Mizandrontsev, Vyacheslav G. Ivanov, Valery N. Sinyukovich, Mikhail N. Granin, Vadim V. Blinov
Summary: The construction of a dam for the Irkutsk hydroelectric power plant caused the water level in Lake Baikal to increase, leading to a migration of the gas hydrate stability zone in the sediment of the lake. The transition process involved the formation of new gas hydrates, a decrease in methane transfer, and a decrease in methane concentrations in the water. In the future, Lake Baikal may return to a stationary state with higher methane concentrations, which could have adverse effects on the ecosystem.
ENVIRONMENTAL EARTH SCIENCES
(2023)
Article
Materials Science, Multidisciplinary
Ji-hye Kim, Jong Mok Ok, Joonyoung Choi, Woun Kang, Jun Sung Kim, Younjung Jo
Summary: This paper investigates the relationship between the vortex pinning energy U-0/k(B) and the pressure-induced phases in FeSe single crystal. It is found that the dependence of U-0/k(B) on pressure at higher magnetic fields follows a similar trend as critical temperature T-c(p) and average Fermi velocity v over line (upsilon) over bar (F)(p). On the other hand, at lower magnetic fields, U-0/k(B) increases significantly before the occurrence of antiferromagnetic (AFM) long-range order, suggesting the presence of additional pinning sites possibly correlated with AFM domain boundaries. The paper also provides a universal description of the vortex dynamics in FeSe.
Article
Geosciences, Multidisciplinary
P. Alken, E. Thebault, C. D. Beggan, H. Amit, J. Aubert, J. Baerenzung, T. N. Bondar, W. J. Brown, S. Califf, A. Chambodut, A. Chulliat, G. A. Cox, C. C. Finlay, A. Fournier, N. Gillet, A. Grayver, M. D. Hammer, M. Holschneider, L. Huder, G. Hulot, T. Jager, C. Kloss, M. Korte, W. Kuang, A. Kuvshinov, B. Langlais, J. -M. Leger, V. Lesur, P. W. Livermore, F. J. Lowes, S. Macmillan, W. Magnes, M. Mandea, S. Marsal, J. Matzka, M. C. Metman, T. Minami, A. Morschhauser, J. E. Mound, M. Nair, S. Nakano, N. Olsen, F. J. Pavon-Carrasco, V. G. Petrov, G. Ropp, M. Rother, T. J. Sabaka, S. Sanchez, D. Saturnino, N. R. Schnepf, X. Shen, C. Stolle, A. Tangborn, L. Toffner-Clausen, H. Toh, J. M. Torta, J. Varner, F. Vervelidou, P. Vigneron, I. Wardinski, J. Wicht, A. Woods, Y. Yang, Z. Zeren, B. Zhou
Summary: The IAGA V-MOD working group adopted the thirteenth generation of the IGRF in December 2019, which includes definitive main field models for epoch 2015.0 and 2020.0, as well as predictive linear secular variations for 2020.0 to 2025.0. This update provides equations, spherical harmonic coefficients, and maps for magnetic parameters and their predicted changes from 2020.0 to 2025.0.
EARTH PLANETS AND SPACE
(2021)
Article
Geosciences, Multidisciplinary
Yanyan Yang, Gauthier Hulot, Pierre Vigneron, Xuhui Shen, Zeren Zhima, Bin Zhou, Werner Magnes, Nils Olsen, Lars Toffner-Clausen, Jianpin Huang, Xuemin Zhang, Shigeng Yuan, Lanwei Wang, Bingjun Cheng, Andreas Pollinger, Roland Lammegger, Jianpin Dai, Jun Lin, Feng Guo, Jingbo Yu, Jie Wang, Yingyan Wu, Xudong Zhao, Xinghong Zhu
Summary: Using magnetic field data from the CSES mission, a high-quality global geomagnetic field model CGGM was derived, which was used as a candidate model for IGRF-13 2020 and showed remarkable agreement with other models. Validation of this model also demonstrated its potential for long-term monitoring of the main field.
EARTH PLANETS AND SPACE
(2021)
Article
Geosciences, Multidisciplinary
P. Alken, A. Chulliat, M. Nair
Summary: This study presents the methodology of deriving candidate models for the Earth's magnetic field using Swarm satellite data and ground observatory data, and compares and evaluates them with previous IGRF models. Ground observatories played a crucial role in validating the models.
EARTH PLANETS AND SPACE
(2021)
Article
Geosciences, Multidisciplinary
P. Alken, E. Thebault, C. D. Beggan, J. Aubert, J. Baerenzung, W. J. Brown, S. Califf, A. Chulliat, G. A. Cox, C. C. Finlay, A. Fournier, N. Gillet, M. D. Hammer, M. Holschneider, G. Hulot, M. Korte, V. Lesur, P. W. Livermore, F. J. Lowes, S. Macmillan, M. Nair, N. Olsen, G. Ropp, M. Rother, N. R. Schnepf, C. Stolle, H. Toh, F. Vervelidou, P. Vigneron, I. Wardinski
Summary: The 13th revision of the International Geomagnetic Reference Field (IGRF) was released in December 2019, comprising two new main field models and a model of predicted secular variation. These models were produced from candidates submitted by fifteen international teams. The evaluation process, final product derivation approach, and retrospective analysis of the IGRF-12 SV candidates are documented in this study, suggesting potential benefits of combining core modeling with satellite observations for forecasting secular variation.
EARTH PLANETS AND SPACE
(2021)
Article
Engineering, Multidisciplinary
Jie Wang, XuHui Shen, YanYan Yang, ZhiMa Zeren, Gauthier Hulot, Nils Olsen, Bin Zhou, Werner Magnes, Angelo De Santis, JianPing Huang, Feng Guo, WenLong Liu, JingBo Yu
Summary: The China Seismo-Electromagnetic Satellite (CSES) successfully launched in February 2018 is the first satellite of China that aims to measure geophysical fields with scientific goals in space and solid earth physics. Using high-precision magnetometers, the CSES magnetic data was utilized to extract the lithospheric magnetic field signal caused by magnetized rocks. A lithospheric magnetic anomaly map over China and surrounding regions was derived, revealing four major magnetic anomalies with origins potentially linked to large-scale tectonic-magmatic activities. Further data processing and multi-source data merging are necessary to enhance the precision of the lithospheric magnetic field model.
SCIENCE CHINA-TECHNOLOGICAL SCIENCES
(2021)
Article
Astronomy & Astrophysics
Yanyan Yang, Bin Zhou, Gauthier Hulot, Nils Olsen, Yingyan Wu, Chao Xiong, Claudia Stolle, Zeren Zhima, Jianping Huang, Xinghong Zhu, Andreas Pollinger, Bingjun Cheng, Werner Magnes, Xudong Zhao, Xuhui Shen
Summary: The high precision magnetometer on the China Seismo-Electromagnetic Satellite (CSES) aims to provide accurate magnetic field measurements, which have been preliminarily validated by comparing with data from other satellites. The data can be used to derive a satellite-derived index equivalent to the Dst index, demonstrating its potential in magnetic field research.
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
(2021)
Article
Astronomy & Astrophysics
M. Fillion, G. Hulot, P. Alken, A. Chulliat, P. Vigneron
Summary: This study introduces a new multispacecraft method for estimating the electric current density vector in the ionospheric F region, showcasing a rigorous mathematical treatment and validation of the algorithm. Results show expected characteristics of F-region interhemispheric field-aligned currents and reveal potentially associated new features with dynamo and pressure currents.
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
(2021)
Article
Geochemistry & Geophysics
K. Gwirtz, T. Davis, M. Morzfeld, C. Constable, A. Fournier, G. Hulot
Summary: This article explores the feasibility of using machine learning techniques to identify precursors of geomagnetic reversals. Through testing with different models and observational records, it is found that the current techniques are not capable of reliably identifying precursors, mainly due to limited data and low frequency resolution.
GEOPHYSICAL JOURNAL INTERNATIONAL
(2022)
Article
Geosciences, Multidisciplinary
Samuel Califf, Patrick Alken, Arnaud Chulliat, Brian Anderson, Kenneth Rock, Sarah Vines, Robin Barnes, Kan Liou
Summary: This study explores the possibility of developing future World Magnetic Models (WMMs) using data from the Iridium satellite constellation. The Iridium data is calibrated and shown to meet the WMM error tolerances, indicating that Iridium is a viable data source for future WMMs.
EARTH PLANETS AND SPACE
(2022)
Article
Astronomy & Astrophysics
M. Fillion, G. Hulot, P. Alken, A. Chulliat
Summary: We propose a new empirical model of F-region ionospheric currents and magnetic fields during quiet times. The model accurately represents these currents and fields in low and mid latitudes. By separating spatial and climatological variations and considering measurement errors and data sampling, the model describes the toroidal magnetic fields and radial poloidal electric currents at two altitudes in the F region. It identifies and reproduces the characteristics of interhemispheric field-aligned currents (IHFACs), providing new insights into their daily variations and longitudinal variations.
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
(2023)
Article
Astronomy & Astrophysics
Manoj Nair, Rob Redmon, Li-Yin Young, Arnaud Chulliat, Belinda Trotta, Christine Chung, Greg Lipstein, Isaac Slavitt
Summary: Enhanced interaction between solar-wind and Earth's magnetosphere can cause space weather and geomagnetic storms that have the potential to damage critical technologies. The disturbance-storm-time (Dst) index is used to measure the severity of geomagnetic storms. Machine-Learning (ML) models have shown promise in forecasting Dst solely from solar wind observations, but many are not suitable for operational use. An open data-science challenge called MagNet attracted participants to develop ML models for predicting Dst. The top models that met the evaluation criteria are operationally viable and suitable for NOAA's needs.
SPACE WEATHER-THE INTERNATIONAL JOURNAL OF RESEARCH AND APPLICATIONS
(2023)
Article
Geochemistry & Geophysics
K. Gwirtz, M. Morzfeld, A. Fournier, G. Hulot
Summary: This study focuses on predicting reversals of Earth's axial magnetic dipole field based on the intensity of the dipole. The prediction strategy varies in skill across different numerical models, serving as an additional criterion to identify Earth-like models. Applying threshold-based predictions to paleomagnetic reconstructions suggests moderate skill in predicting Earth's dynamo over the last two million years.
GEOPHYSICAL JOURNAL INTERNATIONAL
(2021)