The Experts below are selected from a list of 102636 Experts worldwide ranked by ideXlab platform
Konstantin Batygin - One of the best experts on this subject based on the ideXlab platform.
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magnetic origins of the stellar mass obliquity correlation in planetary systems
The Astrophysical Journal, 2015Co-Authors: Christopher Spalding, Konstantin BatyginAbstract:Detailed observational characterization of transiting exoplanet systems has revealed that the spin-axes of massive M ≳ 1.2M_☉ stars often exhibit substantial Misalignments with respect to the orbits of the planets they host. Conversely, lower-mass stars tend to only have limited obliquities. A similar trend has recently emerged within the observational data set of young stars' magnetic field strengths: massive T-Tauri stars tend to have dipole fields that are ~10 times weaker than their less-massive counterparts. Here we show that the associated dependence of magnetic star–disk torques upon stellar mass naturally explains the observed spin–orbit Misalignment trend, provided that Misalignments are obtained within the disk-hosting phase. Magnetic torques act to realign the stellar spin-axes of lower-mass stars with the disk plane on a timescale significantly shorter than the typical disk lifetime, whereas the same effect operates on a much longer timescale for massive stars. Cumulatively, our results point to a primordial excitation of extrasolar spin–orbit Misalignment, signalling consistency with disk-driven migration as the dominant transport mechanism for short-period planets. Furthermore, we predict that spin–orbit Misalignments in systems where close-in planets show signatures of dynamical, post-nebular emplacement will not follow the observed correlation with stellar mass.
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magnetic origins of the stellar mass obliquity correlation in planetary systems
arXiv: Earth and Planetary Astrophysics, 2015Co-Authors: Christopher Spalding, Konstantin BatyginAbstract:Detailed observational characterization of transiting exoplanet systems has revealed that the spin-axes of massive (M > ~1.2 solar masses) stars often exhibit substantial Misalignments with respect to the orbits of the planets they host. Conversely, lower-mass stars tend to only have limited obliquities. A similar trend has recently emerged within the observational dataset of young stars' magnetic field strengths: massive T-Tauri stars tend to have dipole fields that are ~10 times weaker than their less-massive counterparts. Here we show that the associated dependence of magnetic star-disk torques upon stellar mass naturally explains the observed spin-orbit Misalignment trend, provided that Misalignments are obtained within the disk-hosting phase. Magnetic torques act to realign the stellar spin-axes of lower-mass stars with the disk plane on a timescale significantly shorter than the typical disk lifetime, whereas the same effect operates on a much longer timescale for massive stars. Cumulatively, our results point to a primordial excitation of extrasolar spin-orbit Misalignment, signalling consistency with disk-driven migration as the dominant transport mechanism for short-period planets. Furthermore, we predict that spin-orbit Misalignments in systems where close-in planets show signatures of dynamical, post-nebular emplacement will not follow the observed correlation with stellar mass.
Christopher Spalding - One of the best experts on this subject based on the ideXlab platform.
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magnetic origins of the stellar mass obliquity correlation in planetary systems
The Astrophysical Journal, 2015Co-Authors: Christopher Spalding, Konstantin BatyginAbstract:Detailed observational characterization of transiting exoplanet systems has revealed that the spin-axes of massive M ≳ 1.2M_☉ stars often exhibit substantial Misalignments with respect to the orbits of the planets they host. Conversely, lower-mass stars tend to only have limited obliquities. A similar trend has recently emerged within the observational data set of young stars' magnetic field strengths: massive T-Tauri stars tend to have dipole fields that are ~10 times weaker than their less-massive counterparts. Here we show that the associated dependence of magnetic star–disk torques upon stellar mass naturally explains the observed spin–orbit Misalignment trend, provided that Misalignments are obtained within the disk-hosting phase. Magnetic torques act to realign the stellar spin-axes of lower-mass stars with the disk plane on a timescale significantly shorter than the typical disk lifetime, whereas the same effect operates on a much longer timescale for massive stars. Cumulatively, our results point to a primordial excitation of extrasolar spin–orbit Misalignment, signalling consistency with disk-driven migration as the dominant transport mechanism for short-period planets. Furthermore, we predict that spin–orbit Misalignments in systems where close-in planets show signatures of dynamical, post-nebular emplacement will not follow the observed correlation with stellar mass.
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magnetic origins of the stellar mass obliquity correlation in planetary systems
arXiv: Earth and Planetary Astrophysics, 2015Co-Authors: Christopher Spalding, Konstantin BatyginAbstract:Detailed observational characterization of transiting exoplanet systems has revealed that the spin-axes of massive (M > ~1.2 solar masses) stars often exhibit substantial Misalignments with respect to the orbits of the planets they host. Conversely, lower-mass stars tend to only have limited obliquities. A similar trend has recently emerged within the observational dataset of young stars' magnetic field strengths: massive T-Tauri stars tend to have dipole fields that are ~10 times weaker than their less-massive counterparts. Here we show that the associated dependence of magnetic star-disk torques upon stellar mass naturally explains the observed spin-orbit Misalignment trend, provided that Misalignments are obtained within the disk-hosting phase. Magnetic torques act to realign the stellar spin-axes of lower-mass stars with the disk plane on a timescale significantly shorter than the typical disk lifetime, whereas the same effect operates on a much longer timescale for massive stars. Cumulatively, our results point to a primordial excitation of extrasolar spin-orbit Misalignment, signalling consistency with disk-driven migration as the dominant transport mechanism for short-period planets. Furthermore, we predict that spin-orbit Misalignments in systems where close-in planets show signatures of dynamical, post-nebular emplacement will not follow the observed correlation with stellar mass.
Xuling Chen - One of the best experts on this subject based on the ideXlab platform.
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modeling and optimization of magnetically coupled resonant wireless power transfer system with varying spatial scales
IEEE Transactions on Power Electronics, 2017Co-Authors: Fuxin Liu, Yong Yang, Dan Jiang, Xinbo Ruan, Xuling ChenAbstract:Previous work reveals that the magnetically coupled resonant (MCR) wireless power transfer (WPT) technology is efficient and practical for mid-range wireless energy transmission, able to handle nontrivial amount of power. Due to the variable coupling coefficient under lateral Misalignment and angular Misalignment between transmitting coils and receiving coils, the output power and transmission efficiency will fluctuate, leading to instability of the system. This paper presented an equivalent analytical model for the MCR WPT system to incorporate spatial Misalignments. The mutual inductance formulas were derived when receiving coils are laterally, angularly or generally misaligned from transmitting coils. The relationship among the output power, transmission efficiency, the mutual inductance, and load resistance were analyzed in detail. For the design of the MCR WPT system, it is necessary to seek optimal transmission performance under different applications. To achieve maximum output power and high stability of power transfer in a specific Misalignments range, a normalization method based on the obtained analytical model was introduced, providing critical insight into the optimal design of coils. Relative design considerations and optimization procedures were further stated. Experiments had also been carried out to evaluate the accuracy of theoretical analysis and confirm the validity of the proposed optimization method.
Vedvik, Nils Pette - One of the best experts on this subject based on the ideXlab platform.
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Effects of Wind-Wave Misalignment on a Wind Turbine Blade Mating Process: Impact Velocities, Blade Root Damages and Structural SafetyAssessment
'Springer Science and Business Media LLC', 2020Co-Authors: Verma, Amri Shanka, Jiang Zhiyu, Re Zhengru, Gao Zhe, Vedvik, Nils PetteAbstract:Most wind turbine blades are assembled piece-by-piece onto the hub of a monopile-type offshore wind turbine using jack-up crane vessels. Despite the stable foundation of the lifting cranes, the mating process exhibits substantial relative responses amidst blade root and hub. These relative motions are combined effects of wave-induced monopile motions and wind-induced blade root motions, which can cause impact loads at the blade root’s guide pin in the course of alignment procedure. Environmental parameters including the wind-wave Misalignments play an important role for the safety of the installation tasks and govern the impact scenarios. The present study investigates the effects of wind-wave Misalignments on the blade root mating process on a monopile-type offshore wind turbine. The dynamic responses including the impact velocities between root and hub in selected wind-wave Misalignment conditions are investigated using multibody simulations. Furthermore, based on a finite element study, different impact-induced failure modes at the blade root for sideways and head-on impact scenarios, developed due to wind-wave Misalignment conditions, are investigated. Finally, based on extreme value analyses of critical responses, safe domain for the mating task under different wind-wave Misalignments is compared. The results show that although misaligned wind-wave conditions develop substantial relative motions between root and hub, aligned wind-wave conditions induce largest impact velocities and develop critical failure modes at a relatively low threshold velocity of impact.Aerospace Manufacturing Technologie
Nils Petter Vedvik - One of the best experts on this subject based on the ideXlab platform.
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Effects of Wind-Wave Misalignment on a Wind Turbine Blade Mating Process: Impact Velocities, Blade Root Damages and Structural SafetyAssessment
Journal of Marine Science and Application, 2020Co-Authors: Amrit Shankar Verma, Zhiyu Jiang, Nils Petter VedvikAbstract:Most wind turbine blades are assembled piece-by-piece onto the hub of a monopile-type offshore wind turbine using jack-up crane vessels. Despite the stable foundation of the lifting cranes, the mating process exhibits substantial relative responses amidst blade root and hub. These relative motions are combined effects of wave-induced monopile motions and wind-induced blade root motions, which can cause impact loads at the blade root’s guide pin in the course of alignment procedure. Environmental parameters including the wind-wave Misalignments play an important role for the safety of the installation tasks and govern the impact scenarios. The present study investigates the effects of wind-wave Misalignments on the blade root mating process on a monopile-type offshore wind turbine. The dynamic responses including the impact velocities between root and hub in selected wind-wave Misalignment conditions are investigated using multibody simulations. Furthermore, based on a finite element study, different impact-induced failure modes at the blade root for sideways and head-on impact scenarios, developed due to wind-wave Misalignment conditions, are investigated. Finally, based on extreme value analyses of critical responses, safe domain for the mating task under different wind-wave Misalignments is compared. The results show that although misaligned wind-wave conditions develop substantial relative motions between root and hub, aligned wind-wave conditions induce largest impact velocities and develop critical failure modes at a relatively low threshold velocity of impact.
