Feed aggregator

Energy management of space probe based on fuzzy-model predictive control strategy

Publication date: Available online 12 February 2025

Source: Advances in Space Research

Author(s): Yuan Jiang, Zhan Lei, Liying Zhu, Shuo Liu, Suliang Ma

Research on multi-objective control algorithm for micro-nano satellite formation based on array signal detection

Publication date: Available online 11 February 2025

Source: Advances in Space Research

Author(s): Jiao Wang, Boao Zhu, Chengshang Li, Chong Sun, Yawei Wan

An ancient seafloor spreading slowdown may have slashed sea levels

Phys.org: Earth science - Mon, 02/24/2025 - 17:54
Today we are witnessing rapid global sea level rise attributable mostly to climate change–driven melting of ice sheets and glaciers and thermal expansion of seawater. However, sea level change also occurs over millions of years as geological processes gradually reshape Earth's ocean basins and change their total storage volume.

Scientists track evolution of pumice rafts after 2021 underwater eruption in Japan

Phys.org: Earth science - Mon, 02/24/2025 - 16:56
Researchers from Tokyo Metropolitan University have carried out an unprecedentedly detailed survey of pumice rafts in the aftermath of the 2021 Fukutoku-Oka-no-Ba volcanic eruption in Japan. Using samples from 213 different locations, they considered raft density, the size and roundness of individual pumice, and biological species attached.

Simulation reveals ancient Earth had green oceans

Phys.org: Earth science - Mon, 02/24/2025 - 16:36
A team of astrophysicists, geoscientists, chemists and life scientists affiliated with a host of institutions in Japan has found evidence that billions of years ago, the Earth's oceans were green. In their study published in the journal Nature Ecology & Evolution, the group used a variety of environmental factors to create a simulation of Earth several billion years ago.

Integrated study of magnetohydrodynamic stability in the HL-2A tokamak

Physical Review E (Plasma physics) - Mon, 02/24/2025 - 10:00

Author(s): Yong Shen, J. Q. Dong, X. D. Peng, H. D. He, and J. X. Li

The magnetohydrodynamic (MHD) instability in the HL-2A tokamak has been comprehensively studied, including ideal MHD ballooning and kink modes, as well as the operational β limit imposed jointly by them. It shows an internal ballooning mode appearing in the plasma with parabolic pressure and current…


[Phys. Rev. E 111, 025208] Published Mon Feb 24, 2025

An experimental study of the elastic properties of the sandstone flooded with supercritical CO₂: The influences of saturation, pressure, and temperature

Geophysical Journal International - Mon, 02/24/2025 - 00:00
SummaryGeological storage of captured CO₂ is essential for reducing anthropogenic greenhouse gas emissions and ensuring the sustainable use of fossil fuels. Understanding the influence of saturation, pressure, and temperature on the elastic properties of brine-saturated sandstone flooded with supercritical CO₂ is critical for interpreting seismic and sonic logging data, which aids in monitoring and quantifying subsurface changes associated with CO₂ injection. The experimental results indicate that as scCO₂ saturation increases (0∼60 per cent), the P-wave velocity decreases significantly with an average of 14 per cent drop, while the S-wave velocity increases slightly. Temperature variations (80–110°C) have a minimal effect on both velocities (1∼2 per cent), whereas elastic features show noticeable sensitivity to the variation of confining pressure (20-30 MPa) and pore pressure (10-20 MPa). Ignoring the effects of pore pressure might lead to the bias of interpreting seismic data for monitoring scCO₂ saturation change. The constructed rock physics models well capture the coupled effects of porosity and scCO₂ saturation on the P-impedance and P- and S-wave velocity ratio, which show good agreement with the experimental results. These findings are crucial for improving monitoring methods and enhancing the accuracy of predictive models for CO₂ geological storage.

Solar System Elemental Abundances from the Solar Photosphere and CI-Chondrites

Space Science Reviews - Mon, 02/24/2025 - 00:00
Abstract

Solar photospheric abundances and CI-chondrite compositions are reviewed and updated to obtain representative solar system abundances of the elements and their isotopes. The new photospheric abundances obtained here lead to higher solar metallicity. Full 3D NLTE photospheric analyses are only available for 11 elements. A quality index for analyses is introduced. For several elements, uncertainties remain large. Protosolar mass fractions are H (X = 0.7060), He (Y = 0.2753), and for metals Li to U (Z = 0.0187). The protosolar (C+N)/H agrees within 13% with the ratio for the solar core from the Borexino experiment. Elemental abundances in CI-chondrites were screened by analytical methods, sample sizes, and evaluated using concentration frequency distributions. Aqueously mobile elements (e.g., alkalis, alkaline earths, etc.) often deviate from normal distributions indicating mobilization and/or sequestration into carbonates, phosphates, and sulfates. Revised CI-chondrite abundances of non-volatile elements are similar to earlier estimates. The moderately volatile elements F and Sb are higher than before, as are C, Br and I, whereas the CI-abundances of Hg and N are now significantly lower. The solar system nuclide distribution curves of s-process elements agree within 4% with s-process predictions of Galactic chemical evolution models. P-process nuclide distributions are assessed. No obvious correlation of CI-chondritic to solar elemental abundance ratios with condensation temperatures is observed, nor is there one for ratios of CI-chondrites/solar wind abundances.

Contribution of microtopography off the Ryukyu Islands to coastal sea-level amplification during the 2022 Tonga meteotsunami

Earth,Planets and Space - Mon, 02/24/2025 - 00:00
The January 2022 Tonga volcanic eruption generated atmospheric pressure waves that propagated over the ocean’s surface and triggered a meteotsunami. This meteotsunami caused significant amplitudes exceeding 10...

A new ensemble learning method based on signal source driver for GNSS coordinate time series prediction

GPS Solutions - Sun, 02/23/2025 - 00:00
Abstract

Accurately modeling and prediction the nonlinear motion of GNSS (Global Navigation Satellite System) coordinate time series holds significant theoretical and practical value for the study of geodynamics. A novel integrated network, named Ensemble Learning method based on Signal Source Driver (ELSSD), is proposed, which leverages the strengths of Long Short-Term Memory (LSTM) and Deep Self-Attention Neural Network (DSANN), while integrating GNSS loading data as an additional data source. Additionally, a multi-track synchronous sliding window data processing strategy is designed to address the challenge of multi-source data fusion input. The effectiveness of this algorithm is validated using GNSS coordinate time series from 186 global stations over a period of 10 years. Experimental results initially illustrate that, when accounting for displacement caused by environmental loading effects, there is a marked improvement in the modeling and prediction accuracy compared with GNSS input-only. Furthermore, the application of three ensemble network strategies-Bagging, Boosting, and Stacking-have further been demonstrated to enhance modeling and prediction accuracy. Compared with LSTM and DSANN networks, the proposed ELSSD algorithm achieves an average RMSE (Root Mean Square Error) of 3.6 mm for both modeling and prediction, with modeling accuracy improvements of 4.8% and 6.2%, while prediction accuracy improvements of 5.4% and 5.9%, respectively. With respect to the traditional Least Square method, there is an improvement of 22.1% and 27.9% in modeling and prediction accuracy, respectively. Regarding noise characteristics, there is a significant reduction in colored noise amplitude, with decreases of 36.7% and 36.0% observed in modeling and prediction, respectively. Simultaneously, the velocity uncertainty experiences an average reduction of 27.1% and 27.5%. The average velocity differences are measured at 0.06 mm/year and 0.24 mm/year, respectively. Hence, our findings suggest that the ELSSD algorithm emerges as an effective methodology for handling multi-source data input in GNSS coordinate time series, presenting promising practical applications in the field.

Effects in the upper atmosphere and ionosphere in the subauroral region during Victory Day 2024 Geomagnetic Storm (May 10–12, 2024)

Publication date: Available online 11 February 2025

Source: Advances in Space Research

Author(s): A.A. Chernyshov, M.V. Klimenko, I.A. Nosikov, O.P. Borchevkina, A.V. Timchenko, I.I. Efishov, A.A. Sinevich, I.A. Ryakhovsky, G.A. Yakimova, F.S. Bessarab, I.S. Yankovsky, D.V. Chugunin

Analysis of multipath effects on LEO ranging-based positioning using BPSK and BOC signals in urban areas

Publication date: 1 February 2025

Source: Advances in Space Research, Volume 75, Issue 3

Author(s): Qi Zhang, Bing Xu

A non-singular predefined-time sliding mode tracking control for space manipulators

Publication date: 1 February 2025

Source: Advances in Space Research, Volume 75, Issue 3

Author(s): Yuxin Yan, Hutao Cui, Peng Han

Study on the safe landing of a crew module considering horizontal velocity using a DEM-FEM coupling algorithm

Publication date: 1 February 2025

Source: Advances in Space Research, Volume 75, Issue 3

Author(s): Shaomin Liang, Yuntian Feng, Zhihua Wang

Attitude synchronization of chaotic satellites with unknown dynamics using a neural network based fixed time sliding mode controller

Publication date: 1 February 2025

Source: Advances in Space Research, Volume 75, Issue 3

Author(s): Özhan Bingöl

Efficient approach of painting asteroids for planetary defense using network data envelopment analysis

Publication date: 1 February 2025

Source: Advances in Space Research, Volume 75, Issue 3

Author(s): Sajjad Aslani Khiavi, Mahdi Jafari-Nadoushan

Numerical investigation of prediction method for propagation delay of low-frequency radio signal based on the Changhe-II and Loran-C navigation system in East Asia

Publication date: 1 February 2025

Source: Advances in Space Research, Volume 75, Issue 3

Author(s): Jian Wang, Chengsong Duan, Cheng Yang, Qiao Yu

Optical measurements of precipitating relativistic electron microbursts during geomagnetic disturbance and pulsating aurora

Publication date: 1 February 2025

Source: Advances in Space Research, Volume 75, Issue 3

Author(s): Pavel Klimov, Vera Nikolaeva, Konstantin Shchelkanov, Roman Saraev, Ksenia Sigaeva, Andrei Kotikov, Alexander Belov, Boris Kozelov, Alexei Murashov, Alexei Roldugin

On the identification of the spatiotemporal locations of solar wind structures during an intense geomagnetic storm

Publication date: 1 February 2025

Source: Advances in Space Research, Volume 75, Issue 3

Author(s): Victor U. Chukwuma, Bolarinwa J. Adekoya, Eugene O. Onori, Oluwafunmilayo O. Ometan, Aghogho Ogwala

Indian Network for Space Weather Impact Monitoring (InSWIM): An initiative to observe and model the low latitude ionosphere over the Indian longitudes

Publication date: 1 February 2025

Source: Advances in Space Research, Volume 75, Issue 3

Author(s): R.K. Choudhary, K.M. Ambili, C. Vineeth, Ajay Potdar, Md. Mosarraf Hossain, Tarun K. Pant

Theme by Danetsoft and Danang Probo Sayekti inspired by Maksimer