Pub Date : 2024-09-04DOI: 10.1016/j.asr.2024.08.071
Xiang Niu, Hui Liu, Bixin Zhang, Daren Yu
High thrust noise limits the application of microwave discharge ion thruster (MDIT) on space gravitational waves (GWs) detection, which needs to be suppressed by a feedback control system. A feedback control experimental platform is established for MDIT choosing microwave power and ion beam current respectively as controlled variable and feedback parameter. Experiments show the feedback control system adjusts screen grid (SG) current by regulating microwave power to compensate for fluctuations of acceleration grid (AG) current, which is mainly because the ability of microwave power to adjust SG current is dramatically stronger than that to adjust AG current. Faced with fluctuations of decreasing flow rate, the feedback control system boosts microwave power to stabilize ion beam current. However, the AG current shows diametrically opposed characteristics for operations with different interception rates under regulation of a feedback control system. Further study shows this phenomenon is the macroscopic reflection of ion trajectories variations on AG current under the function of specific electric field when feedback control system changes the proportions of primary ions and charge exchange (CEX) ions by influencing CEX reaction intensity in the grid system and its downstream region. Analysis of mean free path shows the CEX reaction intensity in the grid system is stronger than that downstream from AG. Therefore, the physical process in the grid system dominates variations of AG current.
高推力噪声限制了微波放电离子推进器（MDIT）在空间引力波（GWs）探测中的应用，需要通过反馈控制系统加以抑制。本文选择微波功率和离子束电流分别作为受控变量和反馈参数，为 MDIT 建立了反馈控制实验平台。实验表明，反馈控制系统通过调节微波功率来调节屏蔽栅（SG）电流，以补偿加速栅（AG）电流的波动，这主要是因为微波功率调节屏蔽栅电流的能力大大强于调节加速栅电流的能力。面对流量下降的波动，反馈控制系统会增强微波功率以稳定离子束电流。然而，在反馈控制系统的调节下，AG 电流在不同截获率的操作中表现出截然相反的特性。进一步的研究表明，这一现象是反馈控制系统通过影响电网系统及其下游区域的电荷交换（CEX）反应强度来改变原生离子和电荷交换（CEX）离子比例时，离子轨迹变化在特定电场作用下对 AG 电流的宏观反映。对平均自由路径的分析表明，电网系统中的 CEX 反应强度要强于 AG 下游的 CEX 反应强度。因此，网格系统中的物理过程主导着 AG 电流的变化。
{"title":"Demonstration of feedback control regulation process for microwave discharge ion thruster in space gravitational wave detection","authors":"Xiang Niu, Hui Liu, Bixin Zhang, Daren Yu","doi":"10.1016/j.asr.2024.08.071","DOIUrl":"https://doi.org/10.1016/j.asr.2024.08.071","url":null,"abstract":"High thrust noise limits the application of microwave discharge ion thruster (MDIT) on space gravitational waves (GWs) detection, which needs to be suppressed by a feedback control system. A feedback control experimental platform is established for MDIT choosing microwave power and ion beam current respectively as controlled variable and feedback parameter. Experiments show the feedback control system adjusts screen grid (SG) current by regulating microwave power to compensate for fluctuations of acceleration grid (AG) current, which is mainly because the ability of microwave power to adjust SG current is dramatically stronger than that to adjust AG current. Faced with fluctuations of decreasing flow rate, the feedback control system boosts microwave power to stabilize ion beam current. However, the AG current shows diametrically opposed characteristics for operations with different interception rates under regulation of a feedback control system. Further study shows this phenomenon is the macroscopic reflection of ion trajectories variations on AG current under the function of specific electric field when feedback control system changes the proportions of primary ions and charge exchange (CEX) ions by influencing CEX reaction intensity in the grid system and its downstream region. Analysis of mean free path shows the CEX reaction intensity in the grid system is stronger than that downstream from AG. Therefore, the physical process in the grid system dominates variations of AG current.","PeriodicalId":50850,"journal":{"name":"Advances in Space Research","volume":null,"pages":null},"PeriodicalIF":2.6,"publicationDate":"2024-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142258502","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-03DOI: 10.1016/j.asr.2024.08.073
Stefano Marmori, Alessandro Morselli
An optimization approach for cartwheel formation acquisition and maintenance in an Earth Displaced heliocentric orbit is presented. This work considers non-gravitational perturbations such as solar radiation pressure, thus extending the studies previously performed for the mission LISA. The problem is tackled as a Nonlinear Programming problem using a multiple shooting method. The optimization process is performed in two steps: first, the orbital elements of each satellite in heliocentric orbit are optimized to guarantee the stability during the science phase hence easing maintenance of the cartwheel formation in presence of orbital perturbations. Then, the obtained initial states are propagated to obtain a set of target orbital states which become the final target of a second optimization covering the transfer phase from Earth. For the science phase optimization presents two alternative cost functions are introduced, one based on the arm-length evolution and one on the arm-length-rate evolution. The performance of each cost function is analysed for different initial displacement angles: for target arm-lengths below 2.5 million kilometers the arm-length cost function provides the best results while no significant difference between the two optimized solutions is observed above this value. The transfer phase optimization presents two different approaches, one considering an injection on a trajectory more favourable for one of the three spacecraft and one considering an injection on an intermediate trajectory which minimizes the overall acquisition cost of all spacecraft. The proposed optimization approach performance are studied on a set of test cases covering both transfer and science phase, showing that stable configuration conditions can be found even in presence of orbital perturbations and that the multiple injection transfer is capable of providing a more homogeneous fuel consumption among the three spacecraft.
介绍了在地球位移日心轨道上获取和维护车轮编队的优化方法。这项工作考虑到了太阳辐射压力等非重力扰动因素，从而扩展了之前为 LISA 任务所做的研究。该问题作为一个非线性编程问题，采用多重射击法进行处理。优化过程分两步进行：首先，对日心轨道上每颗卫星的轨道元素进行优化，以保证科学阶段的稳定性，从而在存在轨道扰动的情况下简化车轮形成的维护。然后，将获得的初始状态进行传播，以获得一组目标轨道状态，这些状态将成为涵盖从地球转移阶段的第二次优化的最终目标。在科学阶段的优化中，引入了两种可供选择的成本函数，一种基于臂长演变，另一种基于臂长速率演变。针对不同的初始位移角，对每种成本函数的性能进行了分析：对于目标臂长低于 250 万公里的情况，臂长成本函数提供了最佳结果，而高于该值时，两种优化方案之间没有明显差异。转移阶段的优化采用了两种不同的方法，一种是考虑在对三个航天器之一更有利的轨迹上注入，另一种是考虑在中间轨迹上注入，使所有航天器的总体获取成本最小。对所提出的优化方法的性能在一组测试案例中进行了研究，涵盖了转移和科学阶段，结果表明，即使存在轨道扰动，也能找到稳定的配置条件，而且多次注入转移能够使三个航天器的燃料消耗更加均匀。
{"title":"Fuel-optimal acquisition and control of a cartwheel formation in Earth displaced heliocentric orbit","authors":"Stefano Marmori, Alessandro Morselli","doi":"10.1016/j.asr.2024.08.073","DOIUrl":"https://doi.org/10.1016/j.asr.2024.08.073","url":null,"abstract":"An optimization approach for cartwheel formation acquisition and maintenance in an Earth Displaced heliocentric orbit is presented. This work considers non-gravitational perturbations such as solar radiation pressure, thus extending the studies previously performed for the mission LISA. The problem is tackled as a Nonlinear Programming problem using a multiple shooting method. The optimization process is performed in two steps: first, the orbital elements of each satellite in heliocentric orbit are optimized to guarantee the stability during the science phase hence easing maintenance of the cartwheel formation in presence of orbital perturbations. Then, the obtained initial states are propagated to obtain a set of target orbital states which become the final target of a second optimization covering the transfer phase from Earth. For the science phase optimization presents two alternative cost functions are introduced, one based on the arm-length evolution and one on the arm-length-rate evolution. The performance of each cost function is analysed for different initial displacement angles: for target arm-lengths below 2.5 million kilometers the arm-length cost function provides the best results while no significant difference between the two optimized solutions is observed above this value. The transfer phase optimization presents two different approaches, one considering an injection on a trajectory more favourable for one of the three spacecraft and one considering an injection on an intermediate trajectory which minimizes the overall acquisition cost of all spacecraft. The proposed optimization approach performance are studied on a set of test cases covering both transfer and science phase, showing that stable configuration conditions can be found even in presence of orbital perturbations and that the multiple injection transfer is capable of providing a more homogeneous fuel consumption among the three spacecraft.","PeriodicalId":50850,"journal":{"name":"Advances in Space Research","volume":null,"pages":null},"PeriodicalIF":2.6,"publicationDate":"2024-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142186840","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-02DOI: 10.1016/j.asr.2024.08.072
Mohammed Atallah, Mohamed Okasha, Ossama Abdelkhalik
This paper presents Guidance and Control (G&C) systems for multi-satellite assembly in proximity operations. The systems utilize the twistor model, which is linearized through Taylor’s series. Decentralized control laws, designed using Linear Quadratic Regulator (LQR) and Model Predictive Control (MPC), are employed to track an energy-optimal trajectory generated using the Hamiltonian approach. Data exchange between satellites and their neighbors is represented using graph theory. The decentralized MPC framework is implemented using the CasADi package. To ensure collision avoidance between the satellites, a repulsive control law is designed, considering symmetric input saturation in the actuators. The proposed G&C systems are tested using a high-fidelity nonlinear satellite relative motion model that incorporates orbital perturbations. Numerical simulations are performed in a MATLAB® environment, and the results are visualized using STK®. Furthermore, a comparative study is conducted to evaluate tracking performance and fuel consumption between the two control methods. The results demonstrate that the use of an optimal trajectory reduces fuel consumption for both control algorithms.
{"title":"Analytic optimal control for multi-satellite assembly using linearized twistor-based model","authors":"Mohammed Atallah, Mohamed Okasha, Ossama Abdelkhalik","doi":"10.1016/j.asr.2024.08.072","DOIUrl":"https://doi.org/10.1016/j.asr.2024.08.072","url":null,"abstract":"This paper presents Guidance and Control (G&C) systems for multi-satellite assembly in proximity operations. The systems utilize the twistor model, which is linearized through Taylor’s series. Decentralized control laws, designed using Linear Quadratic Regulator (LQR) and Model Predictive Control (MPC), are employed to track an energy-optimal trajectory generated using the Hamiltonian approach. Data exchange between satellites and their neighbors is represented using graph theory. The decentralized MPC framework is implemented using the CasADi package. To ensure collision avoidance between the satellites, a repulsive control law is designed, considering symmetric input saturation in the actuators. The proposed G&C systems are tested using a high-fidelity nonlinear satellite relative motion model that incorporates orbital perturbations. Numerical simulations are performed in a MATLAB® environment, and the results are visualized using STK®. Furthermore, a comparative study is conducted to evaluate tracking performance and fuel consumption between the two control methods. The results demonstrate that the use of an optimal trajectory reduces fuel consumption for both control algorithms.","PeriodicalId":50850,"journal":{"name":"Advances in Space Research","volume":null,"pages":null},"PeriodicalIF":2.6,"publicationDate":"2024-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142186844","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-02DOI: 10.1016/j.asr.2024.09.002
Igor V. Moskalenko, Eun-Suk Seo
{"title":"Preface: Progress in cosmic-ray astrophysics and related areas","authors":"Igor V. Moskalenko, Eun-Suk Seo","doi":"10.1016/j.asr.2024.09.002","DOIUrl":"https://doi.org/10.1016/j.asr.2024.09.002","url":null,"abstract":"","PeriodicalId":50850,"journal":{"name":"Advances in Space Research","volume":null,"pages":null},"PeriodicalIF":2.6,"publicationDate":"2024-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142258503","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-02DOI: 10.1016/j.asr.2024.08.064
Farshid Kamareh, Baojun Pang, Wuxiong Cao, Runqiang Chi, Diqi Hu
In the present paper, a comparative study on the load-bearing as well as shielding performance against hypervelocity impact of space debris of sandwich panels with body-centered cubic lattice core is performed numerically in order to evaluate their eligibility to be utilized as the satellite structure. To this end, four types of body-centered cubic lattice structures, with similar areal densities which are assumed to be made of 5A06 aluminum alloy, including BCC, BCCz (BCC reinforced in Z direction), and also BCCz-I and BCCz-II were considered. Whipple shield structure of same material and areal density was also investigated in order to justify the necessity of lattice structures application, especially in protection field. The present study simulates hypervelocity impact of a spherical projectile with 2 mm diameter, represented the space debris, collides with the structures at the velocity range of 2–6 km/s. Current numerical simulation process accuracy and efficiency were verified through comparing its obtained data based on simulating a problem had been investigated at a valid experimental study to the data proposed by the mentioned research. BCCz-II structure which is newly proposed at this study provided outstanding shielding and load-bearing capabilities in comparison to other structures. Furthermore, the detailed effects of projectile impact location and a middle structure placed plate on the protection performance were investigated and the mentioned items were found to have crucial impact on the structure shielding performance.
{"title":"Proposing novel body-centered cubic lattice core sandwich panels as satellite structure","authors":"Farshid Kamareh, Baojun Pang, Wuxiong Cao, Runqiang Chi, Diqi Hu","doi":"10.1016/j.asr.2024.08.064","DOIUrl":"https://doi.org/10.1016/j.asr.2024.08.064","url":null,"abstract":"In the present paper, a comparative study on the load-bearing as well as shielding performance against hypervelocity impact of space debris of sandwich panels with body-centered cubic lattice core is performed numerically in order to evaluate their eligibility to be utilized as the satellite structure. To this end, four types of body-centered cubic lattice structures, with similar areal densities which are assumed to be made of 5A06 aluminum alloy, including BCC, BCCz (BCC reinforced in Z direction), and also BCCz-I and BCCz-II were considered. Whipple shield structure of same material and areal density was also investigated in order to justify the necessity of lattice structures application, especially in protection field. The present study simulates hypervelocity impact of a spherical projectile with 2 mm diameter, represented the space debris, collides with the structures at the velocity range of 2–6 km/s. Current numerical simulation process accuracy and efficiency were verified through comparing its obtained data based on simulating a problem had been investigated at a valid experimental study to the data proposed by the mentioned research. BCCz-II structure which is newly proposed at this study provided outstanding shielding and load-bearing capabilities in comparison to other structures. Furthermore, the detailed effects of projectile impact location and a middle structure placed plate on the protection performance were investigated and the mentioned items were found to have crucial impact on the structure shielding performance.","PeriodicalId":50850,"journal":{"name":"Advances in Space Research","volume":null,"pages":null},"PeriodicalIF":2.6,"publicationDate":"2024-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142186846","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-31DOI: 10.1016/j.asr.2024.08.068
Xinbo Gu, Kohei Yamaguchi, Takaya Inamori, Ji hyun Park
This study investigates the displaced orbit around a near-Earth asteroid for spacecraft achieved via a realistic solar sail with a performance based on the existing technology in a low distance. Using the realistic solar sail to achieve the displaced orbit with a short displaced distance is more difficult compared with using a traditional thruster under two main limitations: The force limitation and the position limitation. Firstly, the solar radiation pressure (SRP) force generated by the solar sail is limited by the solar sail’s property and the sunlight direction. Therefore, the feasibility of maintaining a displaced orbit at an equilibrium point around the asteroid at a low distance using a solar sail with realistic performance is investigated analytically. The results demonstrate that the equilibrium point of the displaced orbit can be achieved. Secondly, the usage of the solar sail is also limited by the position of the spacecraft. The SRP force cannot be generated in the eclipse region wherein sunlight is absent; specifically, in a displaced orbit with a low displaced distance, the position limitation is more notable. To address this challenge, spacecraft dynamics and control using a solar sail are investigated to achieve the displaced orbit, and a method of orbit transfer outside the eclipse region is proposed. Numerical simulations reveal that the spacecraft can maintain the displaced orbit using the solar sail without entering the eclipse region. Moreover, spacecraft can achieve orbit transfer between two equilibrium points without entering the eclipse region by using the solar sail. The impact of non-spherical shape of the primary asteroid is also investigated. Results show that the proposed method can maintain a displaced orbit with errors from the reference state less than 10 % during a limited time span when the primary asteroid has a non-spherical shape.
{"title":"Dynamics and control for spacecraft tracking a displaced orbit around an asteroid exploiting solar sail","authors":"Xinbo Gu, Kohei Yamaguchi, Takaya Inamori, Ji hyun Park","doi":"10.1016/j.asr.2024.08.068","DOIUrl":"https://doi.org/10.1016/j.asr.2024.08.068","url":null,"abstract":"This study investigates the displaced orbit around a near-Earth asteroid for spacecraft achieved via a realistic solar sail with a performance based on the existing technology in a low distance. Using the realistic solar sail to achieve the displaced orbit with a short displaced distance is more difficult compared with using a traditional thruster under two main limitations: The force limitation and the position limitation. Firstly, the solar radiation pressure (SRP) force generated by the solar sail is limited by the solar sail’s property and the sunlight direction. Therefore, the feasibility of maintaining a displaced orbit at an equilibrium point around the asteroid at a low distance using a solar sail with realistic performance is investigated analytically. The results demonstrate that the equilibrium point of the displaced orbit can be achieved. Secondly, the usage of the solar sail is also limited by the position of the spacecraft. The SRP force cannot be generated in the eclipse region wherein sunlight is absent; specifically, in a displaced orbit with a low displaced distance, the position limitation is more notable. To address this challenge, spacecraft dynamics and control using a solar sail are investigated to achieve the displaced orbit, and a method of orbit transfer outside the eclipse region is proposed. Numerical simulations reveal that the spacecraft can maintain the displaced orbit using the solar sail without entering the eclipse region. Moreover, spacecraft can achieve orbit transfer between two equilibrium points without entering the eclipse region by using the solar sail. The impact of non-spherical shape of the primary asteroid is also investigated. Results show that the proposed method can maintain a displaced orbit with errors from the reference state less than 10 % during a limited time span when the primary asteroid has a non-spherical shape.","PeriodicalId":50850,"journal":{"name":"Advances in Space Research","volume":null,"pages":null},"PeriodicalIF":2.6,"publicationDate":"2024-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142186847","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-30DOI: 10.1016/j.asr.2024.08.062
Atefe Arfa-Fathollahkhani, Masoud Minaei
Multitemporal imagery offers a critical advantage by capturing seasonal variations, which are essential for differentiating between land use and land cover (LULC) types. While these types may appear similar when examined at one specific time, they exhibit distinct phenological patterns across different seasons. This temporal depth is crucial for enhancing model accuracy, particularly in heterogeneous landscapes where LULC transitions are frequent and complex. This paper made use of spectral bands and indices of Sentinel-2 from April to September 2020 were utilized for LULC classification using two advanced machine learning models: Random forest (RF) and support vector machine (SVM). The spectral indices include the normalized difference vegetation index (NDVI), normalized difference built-up index (NDBI), and modified normalized water index (MNDWI). The dataset was divided into four temporal feature sets: April-May, June-July, August-September, and the entire period from April-September. For each two-month period, the median values of the spectral bands and indices were used. Both models were evaluated based on overall accuracy, F1-score, Kappa coefficient, precision, and recall. Results indicate that incorporating temporal features enhanced the performance of the chosen models, with overall accuracy increasing from 82.4% to 94.03% for RF and from 75.4% to 93.54% for SVM. Additionally, the RF algorithm demonstrated higher accuracy than the SVM model across various time periods, with notable increases in F1 scores, Kappa statistic, precision, and recall. These improvements underscore the ability of the models to leverage rich temporal and spectral data provided by Sentinel-2 for accurate LULC classification. This study highlights the importance of incorporating temporal dynamics in remote sensing applications to enhance the precision and reliability of LULC classification.
{"title":"Utilizing multitemporal indices and spectral bands of Sentinel-2 to enhance land use and land cover classification with random forest and support vector machine","authors":"Atefe Arfa-Fathollahkhani, Masoud Minaei","doi":"10.1016/j.asr.2024.08.062","DOIUrl":"https://doi.org/10.1016/j.asr.2024.08.062","url":null,"abstract":"Multitemporal imagery offers a critical advantage by capturing seasonal variations, which are essential for differentiating between land use and land cover (LULC) types. While these types may appear similar when examined at one specific time, they exhibit distinct phenological patterns across different seasons. This temporal depth is crucial for enhancing model accuracy, particularly in heterogeneous landscapes where LULC transitions are frequent and complex. This paper made use of spectral bands and indices of Sentinel-2 from April to September 2020 were utilized for LULC classification using two advanced machine learning models: Random forest (RF) and support vector machine (SVM). The spectral indices include the normalized difference vegetation index (NDVI), normalized difference built-up index (NDBI), and modified normalized water index (MNDWI). The dataset was divided into four temporal feature sets: April-May, June-July, August-September, and the entire period from April-September. For each two-month period, the median values of the spectral bands and indices were used. Both models were evaluated based on overall accuracy, F1-score, Kappa coefficient, precision, and recall. Results indicate that incorporating temporal features enhanced the performance of the chosen models, with overall accuracy increasing from 82.4% to 94.03% for RF and from 75.4% to 93.54% for SVM. Additionally, the RF algorithm demonstrated higher accuracy than the SVM model across various time periods, with notable increases in F1 scores, Kappa statistic, precision, and recall. These improvements underscore the ability of the models to leverage rich temporal and spectral data provided by Sentinel-2 for accurate LULC classification. This study highlights the importance of incorporating temporal dynamics in remote sensing applications to enhance the precision and reliability of LULC classification.","PeriodicalId":50850,"journal":{"name":"Advances in Space Research","volume":null,"pages":null},"PeriodicalIF":2.6,"publicationDate":"2024-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142186851","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-30DOI: 10.1016/j.asr.2024.08.065
Neetasha Arya, Amar Kakad
A variety of plasma waves have been detected in the vicinity of the magnetopause by various spacecraft missions. In this paper, utilizing high-resolution data from the Magnetospheric Multiscale (MMS) mission, we present new observations of simultaneous lower hybrid and ion solitary waves in the dusk flank region of Earth’s magnetosphere. All four MMS spacecraft consistently observed this wave activity during their traversal from Earth’s magnetosphere to the magnetosheath. Our analysis suggests that the lower hybrid drift waves, driven by lower-hybrid drift instability, were observed in correlation with density gradients. Furthermore, the analysis indicates that the entire ion bulk population drifts, which drives ion solitary waves. It is found that these waves play a crucial role in particle heating in the dusk flank region of Earth’s magnetosphere.
{"title":"Lower hybrid and solitary waves in dusk flank region of the Earth’s magnetosphere","authors":"Neetasha Arya, Amar Kakad","doi":"10.1016/j.asr.2024.08.065","DOIUrl":"https://doi.org/10.1016/j.asr.2024.08.065","url":null,"abstract":"A variety of plasma waves have been detected in the vicinity of the magnetopause by various spacecraft missions. In this paper, utilizing high-resolution data from the Magnetospheric Multiscale (MMS) mission, we present new observations of simultaneous lower hybrid and ion solitary waves in the dusk flank region of Earth’s magnetosphere. All four MMS spacecraft consistently observed this wave activity during their traversal from Earth’s magnetosphere to the magnetosheath. Our analysis suggests that the lower hybrid drift waves, driven by lower-hybrid drift instability, were observed in correlation with density gradients. Furthermore, the analysis indicates that the entire ion bulk population drifts, which drives ion solitary waves. It is found that these waves play a crucial role in particle heating in the dusk flank region of Earth’s magnetosphere.","PeriodicalId":50850,"journal":{"name":"Advances in Space Research","volume":null,"pages":null},"PeriodicalIF":2.6,"publicationDate":"2024-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142186866","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The multi-point hemispherical grid model (MHGM) utilizes residual of double-differenced observations to extract precise multipath error information. It models the entire network of multipath error effects across different stations to achieve effective error correction. However, because all the parameters are estimated collectively using the least squares method, the increased number of grid point parameters can significantly consume memory, CPU, and other computing resources required for modeling. In response to the computational resource consumption challenge associated with fixed-resolution MHGM in multi-station applications, a space domain adaptive grid division method is proposed to optimize the modeling of multipath errors. This approach utilizes prior distribution information of multipath errors to optimize the grid structure. It reduces the number of grids in areas where multipath errors exhibit minimal changes, and provides detailed parameterization for areas with significant variations. Experimental results demonstrate the effectiveness of this method in significantly reducing the number of estimated parameters using MHGM. In statistical analysis of double-differenced phase observation residuals with fixed ambiguities, as the number of estimated parameters in the MHGM decreases to only 24.6 % of the fixed-resolution approach, memory usage during parameter estimation remains a mere 6 % of that required in the fixed-resolution approach. This highlights its potential value in mitigating multipath errors when modeling GNSS large-scale network data.
{"title":"Optimized multi-point hemispherical grid model with adaptive grid division based on the prior information of multipath error","authors":"Xuan Zou, Yawei Wang, Zhiwen Wu, Weiming Tang, Chen Zhou, Zhiyuan Li, Chenlong Deng, Yangyang Li, Yongfeng Zhang","doi":"10.1016/j.asr.2024.08.063","DOIUrl":"https://doi.org/10.1016/j.asr.2024.08.063","url":null,"abstract":"The multi-point hemispherical grid model (MHGM) utilizes residual of double-differenced observations to extract precise multipath error information. It models the entire network of multipath error effects across different stations to achieve effective error correction. However, because all the parameters are estimated collectively using the least squares method, the increased number of grid point parameters can significantly consume memory, CPU, and other computing resources required for modeling. In response to the computational resource consumption challenge associated with fixed-resolution MHGM in multi-station applications, a space domain adaptive grid division method is proposed to optimize the modeling of multipath errors. This approach utilizes prior distribution information of multipath errors to optimize the grid structure. It reduces the number of grids in areas where multipath errors exhibit minimal changes, and provides detailed parameterization for areas with significant variations. Experimental results demonstrate the effectiveness of this method in significantly reducing the number of estimated parameters using MHGM. In statistical analysis of double-differenced phase observation residuals with fixed ambiguities, as the number of estimated parameters in the MHGM decreases to only 24.6 % of the fixed-resolution approach, memory usage during parameter estimation remains a mere 6 % of that required in the fixed-resolution approach. This highlights its potential value in mitigating multipath errors when modeling GNSS large-scale network data.","PeriodicalId":50850,"journal":{"name":"Advances in Space Research","volume":null,"pages":null},"PeriodicalIF":2.6,"publicationDate":"2024-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142186850","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-30DOI: 10.1016/j.asr.2024.08.069
Qingwei Sun, Jiangang Chao, Wanhong Lin
The study of few-shot semantic segmentation (FSS) for the astronaut work environment (AWE) is of significant importance as it enables the segmentation of unknown categories. However, general FSS methods are predicated on the assumption that the training and testing data belong to the same domain. When this assumption is invalid, the model’s performance is significantly degraded. We propose a more general approach, whereby the model is trained on a generic dataset and tested on a dedicated AWE dataset. This challenging task is referred to as cross-domain few-shot semantic segmentation (CD-FSS). A novel model, namely FTDCNet, is proposed, which comprises a domain-agnostic feature transformation module and a domain-constrained transformer. The FTDCNet model demonstrates superior performance compared to the state-of-the-art (SOTA) model, with an accuracy improvement of 11.83% and 11.42% under 1-shot and 5-shot settings, respectively.
{"title":"Cross-domain few-shot semantic segmentation for the astronaut work environment","authors":"Qingwei Sun, Jiangang Chao, Wanhong Lin","doi":"10.1016/j.asr.2024.08.069","DOIUrl":"https://doi.org/10.1016/j.asr.2024.08.069","url":null,"abstract":"The study of few-shot semantic segmentation (FSS) for the astronaut work environment (AWE) is of significant importance as it enables the segmentation of unknown categories. However, general FSS methods are predicated on the assumption that the training and testing data belong to the same domain. When this assumption is invalid, the model’s performance is significantly degraded. We propose a more general approach, whereby the model is trained on a generic dataset and tested on a dedicated AWE dataset. This challenging task is referred to as cross-domain few-shot semantic segmentation (CD-FSS). A novel model, namely FTDCNet, is proposed, which comprises a domain-agnostic feature transformation module and a domain-constrained transformer. The FTDCNet model demonstrates superior performance compared to the state-of-the-art (SOTA) model, with an accuracy improvement of 11.83% and 11.42% under 1-shot and 5-shot settings, respectively.","PeriodicalId":50850,"journal":{"name":"Advances in Space Research","volume":null,"pages":null},"PeriodicalIF":2.6,"publicationDate":"2024-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142186849","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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