Pub Date : 2024-10-28DOI: 10.1016/j.actaastro.2024.10.047
Cold-gas thrusters play a vital role as a subsystem in satellite operations facilitating space maneuvers in numerous missions. Achieving optimal propulsion necessitates not only continuous development of thruster design but also an exploration of novel propellant options to enhance overall performance. While an ideal propellant remains elusive, many studies have identified alternative options to replace commonly used inert gases. Choosing a solid-state propellant offers benefits such as the absence of a pressurised tank and sloshing effect. Hydrocarbon propellants are advantageous due to their non-corrosiveness and abundance as organic compounds on Earth. The sublimation process for manipulating solid propellants typically requires only a few watts, making it suitable for low-power budget missions. This work presents five solid hydrocarbon propellants for cold-gas thrusters, three of which have not yet been experimentally explored. The comparison between various aspects, including mass flow rate, power consumption, and several key performance parameters, is discussed. The measured mass flow rate is a function of the species and temperature, following the trend of the vapour pressure. The power consumption for all propellants only depends on the required heating temperature as they share similar thermal properties. The thrust generated by each propellant is comparable and linearly proportional to the mass flow rate when the flow is choked. Specific impulse remains relatively constant across different mass flow rates due to the strong correlation between thrust and mass flow rate. The thrust-to-power ratio is generally comparable among the propellants, except hexamine, which demands more power at higher operating temperatures due to increased heat loss. Among these alternatives, camphor emerges as the most promising candidate due to its low power consumption, thrust generation, and mass efficiency. On the other hand, naphthalene offers the best in terms of its superior thrust-to-power ratio and cost-per-kilogram advantage.
{"title":"Exploring potential candidates of alternative solid hydrocarbon propellants for cold-gas thrusters","authors":"","doi":"10.1016/j.actaastro.2024.10.047","DOIUrl":"10.1016/j.actaastro.2024.10.047","url":null,"abstract":"<div><div>Cold-gas thrusters play a vital role as a subsystem in satellite operations facilitating space maneuvers in numerous missions. Achieving optimal propulsion necessitates not only continuous development of thruster design but also an exploration of novel propellant options to enhance overall performance. While an ideal propellant remains elusive, many studies have identified alternative options to replace commonly used inert gases. Choosing a solid-state propellant offers benefits such as the absence of a pressurised tank and sloshing effect. Hydrocarbon propellants are advantageous due to their non-corrosiveness and abundance as organic compounds on Earth. The sublimation process for manipulating solid propellants typically requires only a few watts, making it suitable for low-power budget missions. This work presents five solid hydrocarbon propellants for cold-gas thrusters, three of which have not yet been experimentally explored. The comparison between various aspects, including mass flow rate, power consumption, and several key performance parameters, is discussed. The measured mass flow rate is a function of the species and temperature, following the trend of the vapour pressure. The power consumption for all propellants only depends on the required heating temperature as they share similar thermal properties. The thrust generated by each propellant is comparable and linearly proportional to the mass flow rate when the flow is choked. Specific impulse remains relatively constant across different mass flow rates due to the strong correlation between thrust and mass flow rate. The thrust-to-power ratio is generally comparable among the propellants, except hexamine, which demands more power at higher operating temperatures due to increased heat loss. Among these alternatives, camphor emerges as the most promising candidate due to its low power consumption, thrust generation, and mass efficiency. On the other hand, naphthalene offers the best in terms of its superior thrust-to-power ratio and cost-per-kilogram advantage.</div></div>","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":null,"pages":null},"PeriodicalIF":3.1,"publicationDate":"2024-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142572361","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-24DOI: 10.1016/j.actaastro.2024.10.060
Background
The hindlimb unloaded (HU) mouse model exhibits disuse-induced muscle atrophy. However, effective interventions remain elusive. We investigated the therapeutic potential of mesenchymal stem cells (MSC) transplant on muscle decline in HU mice.
Methods
We divided 4-month-old male c57BL/6j mice into controls and HU mice treated with PBS as placebo (HU-PBS) or MSCs (HU-MSC; one million cells/100 μl PBS into gastrocnemius muscles once a week) for three weeks. We measured muscle mass, grip strength, and an unbiased transcriptome analysis of gastrocnemius muscles.
Results
MSC treatment prevented muscle atrophy and improved grip strength in HU mice. Transcriptome analysis revealed MSC-induced unique (557 genes) and differential (1214 genes) expressions of several genes compared to the HU-PBS group. GO and KEGG term analysis revealed an HU-induced downregulation of pathways associated with the regulation of contractile apparatus, neuromuscular junction, and satellite cell function, which were partly reversed with MSC treatment. Lastly, MSC treatment also upregulated the pathways controlling muscle differentiation and growth in the HU mice.
Conclusion
Altogether, we report the therapeutic potential of MSCs in treating disuse-induced muscle atrophy and weakness. Our study may help unravel novel molecular mechanisms involved in MSCs-induced muscle restoration.
{"title":"Mesenchymal stem cell transplant as an intervention to ameliorate disuse-induced muscle atrophy in a mouse model of simulated microgravity","authors":"","doi":"10.1016/j.actaastro.2024.10.060","DOIUrl":"10.1016/j.actaastro.2024.10.060","url":null,"abstract":"<div><h3>Background</h3><div>The hindlimb unloaded (HU) mouse model exhibits disuse-induced muscle atrophy. However, effective interventions remain elusive. We investigated the therapeutic potential of mesenchymal stem cells (MSC) transplant on muscle decline in HU mice.</div></div><div><h3>Methods</h3><div>We divided 4-month-old male c57BL/6j mice into controls and HU mice treated with PBS as placebo (HU-PBS) or MSCs (HU-MSC; one million cells/100 μl PBS into gastrocnemius muscles once a week) for three weeks. We measured muscle mass, grip strength, and an unbiased transcriptome analysis of gastrocnemius muscles.</div></div><div><h3>Results</h3><div>MSC treatment prevented muscle atrophy and improved grip strength in HU mice. Transcriptome analysis revealed MSC-induced unique (557 genes) and differential (1214 genes) expressions of several genes compared to the HU-PBS group. GO and KEGG term analysis revealed an HU-induced downregulation of pathways associated with the regulation of contractile apparatus, neuromuscular junction, and satellite cell function, which were partly reversed with MSC treatment. Lastly, MSC treatment also upregulated the pathways controlling muscle differentiation and growth in the HU mice.</div></div><div><h3>Conclusion</h3><div>Altogether, we report the therapeutic potential of MSCs in treating disuse-induced muscle atrophy and weakness. Our study may help unravel novel molecular mechanisms involved in MSCs-induced muscle restoration.</div></div>","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":null,"pages":null},"PeriodicalIF":3.1,"publicationDate":"2024-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142534904","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-24DOI: 10.1016/j.actaastro.2024.10.030
Based on the temperature change data of the penetrator, to achieve in-situ detection of the thermal conductivity of the lunar regolith profile, it is necessary to establish a heat conduction model between the penetrator and the lunar regolith. This study simplifies the heat conduction model of the complex shaped penetrator through simulation analysis results. Then, we proposed a thermal conductivity inversion method based on the transient thermal cylinder source model. The thermal diffusion test was carried out under normal temperature and pressure on a standard reference object with known thermal conductivity and the thermal conductivity inversion work was completed, which verified the feasibility of the inversion method. Then, we completed the thermal diffusion test of the penetrator and the lunar regolith simulant under the simulated low-temperature vacuum environment of the lunar surface, and carried out the thermal conductivity inversion of the lunar regolith simulant based on the thermal diffusion test data, which proved that the proposed thermal inversion method is applicable for the lunar regolith under the low-temperature vacuum. Finally, the thermal conductivity test was conducted on icy lunar regolith simulant with different water contents and a thermal diffusion test in a vacuum low-temperature environment was carried out. The thermal conductivity inversion was completed using the same method, which proved that the inversion method is suitable for icy lunar regolith simulant.
{"title":"Penetration based lunar regolith thermal conductivity inversion: Method and verification","authors":"","doi":"10.1016/j.actaastro.2024.10.030","DOIUrl":"10.1016/j.actaastro.2024.10.030","url":null,"abstract":"<div><div>Based on the temperature change data of the penetrator, to achieve in-situ detection of the thermal conductivity of the lunar regolith profile, it is necessary to establish a heat conduction model between the penetrator and the lunar regolith. This study simplifies the heat conduction model of the complex shaped penetrator through simulation analysis results. Then, we proposed a thermal conductivity inversion method based on the transient thermal cylinder source model. The thermal diffusion test was carried out under normal temperature and pressure on a standard reference object with known thermal conductivity and the thermal conductivity inversion work was completed, which verified the feasibility of the inversion method. Then, we completed the thermal diffusion test of the penetrator and the lunar regolith simulant under the simulated low-temperature vacuum environment of the lunar surface, and carried out the thermal conductivity inversion of the lunar regolith simulant based on the thermal diffusion test data, which proved that the proposed thermal inversion method is applicable for the lunar regolith under the low-temperature vacuum. Finally, the thermal conductivity test was conducted on icy lunar regolith simulant with different water contents and a thermal diffusion test in a vacuum low-temperature environment was carried out. The thermal conductivity inversion was completed using the same method, which proved that the inversion method is suitable for icy lunar regolith simulant.</div></div>","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":null,"pages":null},"PeriodicalIF":3.1,"publicationDate":"2024-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142560868","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-24DOI: 10.1016/j.actaastro.2024.10.044
The DIANA mission represents an underwater analog space mission designed to simulate and study the impact of long-duration spaceflight and extraterrestrial habitation on crew performance, psychosocial dynamics, and technological systems. The mission utilized an underwater habitat, the Hydronaut H03 DeepLab, to mimic the isolated, confined, and extreme (ICE) environment of space. Over eight days, a six-member crew lived and worked in underwater (3) and water surface (3) habitats, performing scientific experiments and operational tasks. The mission schedule encompassed a variety of activities such as drone exploration, extravehicular activities (EVAs), soil sampling, and media interactions, culminating in a simulated departure from the lunar surface. Data collection methods included continuous biomedical monitoring, cognitive task assessments, and sociomapping to analyze team communication and cooperation. This paper provides an overview of the mission architecture and outcomes, offering valuable insights into the challenges of future human space exploration and informing improvements in crew selection, training, and support systems.
{"title":"DIANA: An underwater analog space mission","authors":"","doi":"10.1016/j.actaastro.2024.10.044","DOIUrl":"10.1016/j.actaastro.2024.10.044","url":null,"abstract":"<div><div>The DIANA mission represents an underwater analog space mission designed to simulate and study the impact of long-duration spaceflight and extraterrestrial habitation on crew performance, psychosocial dynamics, and technological systems. The mission utilized an underwater habitat, the Hydronaut H03 DeepLab, to mimic the isolated, confined, and extreme (ICE) environment of space. Over eight days, a six-member crew lived and worked in underwater (3) and water surface (3) habitats, performing scientific experiments and operational tasks. The mission schedule encompassed a variety of activities such as drone exploration, extravehicular activities (EVAs), soil sampling, and media interactions, culminating in a simulated departure from the lunar surface. Data collection methods included continuous biomedical monitoring, cognitive task assessments, and sociomapping to analyze team communication and cooperation. This paper provides an overview of the mission architecture and outcomes, offering valuable insights into the challenges of future human space exploration and informing improvements in crew selection, training, and support systems.</div></div>","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":null,"pages":null},"PeriodicalIF":3.1,"publicationDate":"2024-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142538884","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-23DOI: 10.1016/j.actaastro.2024.10.050
A cislunar suspension tether (CST) is a kind of ultra-long tether anchored to the lunar surface and extends to the vicinity of the Earth, looks like hanging to the Moon, could be used as cislunar pathway for interstellar freightage easier. Its feasibility on material mechanics and dynamics has been verified by the authors. This paper focuses on the process of the cargo transport along the CST. A single coupling model is established, which couples the cargo with one single node of the discrete CST model. Merely the interactive force between the coupled node and cargo is considered, with a proper definition description of the cargo's velocity along the CST. The description defines the direction of the cargo's velocity to the next one node on the CST all the time. The dynamic equations of the whole system are established based on afore stipulations. Several examples will be simulated and presented, their results will prove the effectiveness of the single coupling model, while, reflect some interesting phenomena of the CST's work. This paper also explains the advantage of the model by contrasting to some other models with multi nodes actions to the cargo.
{"title":"Dynamic simulation of cargo transport along cislunar suspension tether by single node coupling model","authors":"","doi":"10.1016/j.actaastro.2024.10.050","DOIUrl":"10.1016/j.actaastro.2024.10.050","url":null,"abstract":"<div><div>A cislunar suspension tether (CST) is a kind of ultra-long tether anchored to the lunar surface and extends to the vicinity of the Earth, looks like hanging to the Moon, could be used as cislunar pathway for interstellar freightage easier. Its feasibility on material mechanics and dynamics has been verified by the authors. This paper focuses on the process of the cargo transport along the CST. A single coupling model is established, which couples the cargo with one single node of the discrete CST model. Merely the interactive force between the coupled node and cargo is considered, with a proper definition description of the cargo's velocity along the CST. The description defines the direction of the cargo's velocity to the next one node on the CST all the time. The dynamic equations of the whole system are established based on afore stipulations. Several examples will be simulated and presented, their results will prove the effectiveness of the single coupling model, while, reflect some interesting phenomena of the CST's work. This paper also explains the advantage of the model by contrasting to some other models with multi nodes actions to the cargo.</div></div>","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":null,"pages":null},"PeriodicalIF":3.1,"publicationDate":"2024-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142534903","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-23DOI: 10.1016/j.actaastro.2024.10.008
The Sun-Earth libration point configuration is one of the options for space-based gravitational wave detection. Long-term configuration stability is crucial for high-precision measurements, challenged by the strong nonlinear dynamics of the Sun-Earth three-body system. This paper proposes an efficient design method and determines the feasible parameter domain for the libration point gravitational wave observatory. First, the dynamic model for the libration point configuration is established, and the stability indexes are defined. The sensitive parameters that affect the relative geometric configuration are discussed and the phase angle is found to be the key factor. Then, an efficient design method is proposed, and the procedure is divided into two steps. The phase angle of the Earth phase offset orbit and the libration point configuration are optimized successively. Finally, the proposed method is applied to the LAGRANGE mission concept. The results show that the three stability indexes decrease by 59%, 42% and 23%, respectively. Moreover, a mapping between configuration parameters and stability indexes is established. The feasible parameter domain for the stable libration point configuration is discussed. The feasible amplitudes domain in the and directions of the libration point orbit should be less than 6200 km and 42000 km, respectively, to guarantee configuration stability. This research could provide a reference for the stable design and implementation of gravitational wave detection missions utilizing libration point configuration in the future.
太阳-地球 L2 天平点配置是天基引力波探测的选项之一。由于日地三体系统具有很强的非线性动力学特性，长期的配置稳定性对高精度测量至关重要。本文提出了一种高效的设计方法，并确定了天平点引力波观测站的可行参数域。首先，建立了天枰点构型的动力学模型，并定义了稳定性指标。讨论了影响相对几何构型的敏感参数，发现相位角是关键因素。然后，提出了一种高效的设计方法，并将设计过程分为两个步骤。先后优化了地球相位偏移轨道的相位角和天平点配置。最后，将提出的方法应用于 LAGRANGE 任务概念。结果表明，三个稳定性指数分别降低了 59%、42% 和 23%。此外，还建立了配置参数与稳定性指数之间的映射关系。讨论了稳定的天平点配置的可行参数域。为保证构型的稳定性，秤锤点轨道 x 和 z 方向的可行振幅域应分别小于 6200 千米和 42000 千米。该研究可为未来利用 "秤锤点 "构型稳定设计和实施引力波探测任务提供参考。
{"title":"Stable configuration design for libration point gravitational wave observatory","authors":"","doi":"10.1016/j.actaastro.2024.10.008","DOIUrl":"10.1016/j.actaastro.2024.10.008","url":null,"abstract":"<div><div>The Sun-Earth <span><math><msub><mrow><mi>L</mi></mrow><mrow><mn>2</mn></mrow></msub></math></span> libration point configuration is one of the options for space-based gravitational wave detection. Long-term configuration stability is crucial for high-precision measurements, challenged by the strong nonlinear dynamics of the Sun-Earth three-body system. This paper proposes an efficient design method and determines the feasible parameter domain for the libration point gravitational wave observatory. First, the dynamic model for the libration point configuration is established, and the stability indexes are defined. The sensitive parameters that affect the relative geometric configuration are discussed and the phase angle is found to be the key factor. Then, an efficient design method is proposed, and the procedure is divided into two steps. The phase angle of the Earth phase offset orbit and the libration point configuration are optimized successively. Finally, the proposed method is applied to the LAGRANGE mission concept. The results show that the three stability indexes decrease by 59%, 42% and 23%, respectively. Moreover, a mapping between configuration parameters and stability indexes is established. The feasible parameter domain for the stable libration point configuration is discussed. The feasible amplitudes domain in the <span><math><mi>x</mi></math></span> and <span><math><mi>z</mi></math></span> directions of the libration point orbit should be less than 6200 km and 42000 km, respectively, to guarantee configuration stability. This research could provide a reference for the stable design and implementation of gravitational wave detection missions utilizing libration point configuration in the future.</div></div>","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":null,"pages":null},"PeriodicalIF":3.1,"publicationDate":"2024-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142534902","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-23DOI: 10.1016/j.actaastro.2024.10.052
Accurate modeling and simulation (M&S) of spacecraft solar array power under degradation is essential for mission planning, remaining useful life assessment, and lifetime extension. A relevant example is ESA’s Cluster spacecraft fleet, launched in 2000 and operated at the European Space Operation Centre (ESOC), whose solar arrays have suffered severe degradation due to space radiation that has caused challenges to routine operations and mission planning. However, currently available physics-based and machine learning models have been proven ineffective in modeling the drastic reduction in power generation over the long operational life of the spacecraft.
In response to these limitations, this work introduces a framework to model solar array degradation and predict power generation. It embeds a novel simplified physics-based model and a meta-heuristic optimization algorithm which exploits domain-specific knowledge and monitoring data for robust model parameter calibration and accurate power generation predictions. The results show the effectiveness of the proposed approach in avoiding overfitting and providing an accurate estimate of Cluster solar array power evolution.
{"title":"A novel physics-based computational framework to model spacecraft solar array power under degradation: Application to European Space Agency (ESA) Cluster mission","authors":"","doi":"10.1016/j.actaastro.2024.10.052","DOIUrl":"10.1016/j.actaastro.2024.10.052","url":null,"abstract":"<div><div>Accurate modeling and simulation (M&S) of spacecraft solar array power under degradation is essential for mission planning, remaining useful life assessment, and lifetime extension. A relevant example is ESA’s Cluster spacecraft fleet, launched in 2000 and operated at the European Space Operation Centre (ESOC), whose solar arrays have suffered severe degradation due to space radiation that has caused challenges to routine operations and mission planning. However, currently available physics-based and machine learning models have been proven ineffective in modeling the drastic reduction in power generation over the long operational life of the spacecraft.</div><div>In response to these limitations, this work introduces a framework to model solar array degradation and predict power generation. It embeds a novel simplified physics-based model and a meta-heuristic optimization algorithm which exploits domain-specific knowledge and monitoring data for robust model parameter calibration and accurate power generation predictions. The results show the effectiveness of the proposed approach in avoiding overfitting and providing an accurate estimate of Cluster solar array power evolution.</div></div>","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":null,"pages":null},"PeriodicalIF":3.1,"publicationDate":"2024-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142538883","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-23DOI: 10.1016/j.actaastro.2024.10.054
The relevance of research aimed at developing diagnostic technologies for electromechanical actuators is due to the need to improve flight safety in conditions of increasing intensity of highly electrified aircraft and spacecraft operations. The paper discusses one of the promising approaches to electromechanical actuator health management, which involves the use of machine learning methods to synthesize health monitoring algorithms. Machine learning methods make it possible to build classification models based on empirical data, which are used to generate recommendations for making operational decisions. Empirical data, which is a source of valuable experience and the basis of a training sample necessary for formalizing patterns in classification models, can be formed as a result of life tests, mathematical modeling, and actuator operation. In order to improve the safety of space flights, the article focuses on the integration of electromechanical actuator mathematical model methods, optimal space filling, and machine learning. Optimal space filling methods are used to reduce the computational costs associated with representative training sampling. Examples of developing classification models are given to determine failures associated with changes in gear (backlash, Coulomb friction and viscous friction) which is the most critical actuator link. As a result of computational studies, the main advantages of the proposed approach to the synthesis of electromechanical actuator health assessment algorithms are shown.
{"title":"Machine learning-based synthesis of diagnostic algorithms for electromechanical actuators to improve the aerospace flight safety","authors":"","doi":"10.1016/j.actaastro.2024.10.054","DOIUrl":"10.1016/j.actaastro.2024.10.054","url":null,"abstract":"<div><div>The relevance of research aimed at developing diagnostic technologies for electromechanical actuators is due to the need to improve flight safety in conditions of increasing intensity of highly electrified aircraft and spacecraft operations. The paper discusses one of the promising approaches to electromechanical actuator health management, which involves the use of machine learning methods to synthesize health monitoring algorithms. Machine learning methods make it possible to build classification models based on empirical data, which are used to generate recommendations for making operational decisions. Empirical data, which is a source of valuable experience and the basis of a training sample necessary for formalizing patterns in classification models, can be formed as a result of life tests, mathematical modeling, and actuator operation. In order to improve the safety of space flights, the article focuses on the integration of electromechanical actuator mathematical model methods, optimal space filling, and machine learning. Optimal space filling methods are used to reduce the computational costs associated with representative training sampling. Examples of developing classification models are given to determine failures associated with changes in gear (backlash, Coulomb friction and viscous friction) which is the most critical actuator link. As a result of computational studies, the main advantages of the proposed approach to the synthesis of electromechanical actuator health assessment algorithms are shown.</div></div>","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":null,"pages":null},"PeriodicalIF":3.1,"publicationDate":"2024-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142534901","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-23DOI: 10.1016/j.actaastro.2024.10.059
<div><div>The sharp morphological features of lunar dust particles generate significant elastic–plastic contact forces and deformations upon contact with material surfaces, which considerably affect the mechanical properties of lunar dust particles, including their contact, collision, adhesion, transport, and wear characteristics. Despite these severe effects, valid models considering the contact characteristics of typical sharp-featured lunar dust particles are currently lacking. This study proposes an elastic–plastic contact model for nonrotationally symmetric lunar dust particles showing typical sharp features. Detailed derivations of the expressions for various physical responses observed when lunar dust particles establish normal contacts with elastic and elastic–plastic half-spaces under adhesive conditions are also provided. These include derivations for elastic forces, elastic–plastic forces, contact areas, pull-off forces, residual displacements, and plastic deformation areas. Furthermore, the tangential pull-off force during the tangential loading of lunar dust particles is derived, and the tangential contact characteristics are explored. Comparisons of the results of the proposed model with those of previous experiments reveal that the proposed model shows errors of only 6.06 % and 1.03 % in the maximum indentation depth and residual displacement, respectively. These errors are substantially lower than those of conventional spherical models (60.30 % and 60.13 %, respectively), confirming the superior accuracy of the proposed model. Furthermore, the discrete element method is employed to analyze the effects of normal and tangential contacts, dynamic characteristics, and plastic deformations on the considered lunar dust particles. The results are then compared with those of existing contact models. They reveal that maximum elastic–plastic forces under normal contact conditions are positively correlated with the initial velocity but negatively correlated with the lateral angle. Furthermore, the tangential pull-off force is positively correlated with the normal force and surface energy. In addition, the contact duration of lunar dust particles is positively correlated with their initial velocities, while the residual displacement is negatively correlation. For instance, as the initial velocity increases from 10 to 50 m/s, the maximum elastic–plastic force increases from 37.64 to 321.72 mN. Comparisons of the proposed model with other contact models reveal that the maximum elastic–plastic force of the elastic–plastic triangular pyramid model is only 14.93 % that of the cylindrical model, 34.23 % that of the spherical model, and 76.27 % that of the conical model, indicating significant reductions in the maximum elastic–plastic force owing to the plastic deformations of particles with typical sharp features. Overall, the results of this study offer crucial insights into the mechanical characteristics of nonspherical lunar dust particles under
{"title":"Modeling the elastic–plastic contact forces and deformations of nonrotationally symmetric lunar dust particles","authors":"","doi":"10.1016/j.actaastro.2024.10.059","DOIUrl":"10.1016/j.actaastro.2024.10.059","url":null,"abstract":"<div><div>The sharp morphological features of lunar dust particles generate significant elastic–plastic contact forces and deformations upon contact with material surfaces, which considerably affect the mechanical properties of lunar dust particles, including their contact, collision, adhesion, transport, and wear characteristics. Despite these severe effects, valid models considering the contact characteristics of typical sharp-featured lunar dust particles are currently lacking. This study proposes an elastic–plastic contact model for nonrotationally symmetric lunar dust particles showing typical sharp features. Detailed derivations of the expressions for various physical responses observed when lunar dust particles establish normal contacts with elastic and elastic–plastic half-spaces under adhesive conditions are also provided. These include derivations for elastic forces, elastic–plastic forces, contact areas, pull-off forces, residual displacements, and plastic deformation areas. Furthermore, the tangential pull-off force during the tangential loading of lunar dust particles is derived, and the tangential contact characteristics are explored. Comparisons of the results of the proposed model with those of previous experiments reveal that the proposed model shows errors of only 6.06 % and 1.03 % in the maximum indentation depth and residual displacement, respectively. These errors are substantially lower than those of conventional spherical models (60.30 % and 60.13 %, respectively), confirming the superior accuracy of the proposed model. Furthermore, the discrete element method is employed to analyze the effects of normal and tangential contacts, dynamic characteristics, and plastic deformations on the considered lunar dust particles. The results are then compared with those of existing contact models. They reveal that maximum elastic–plastic forces under normal contact conditions are positively correlated with the initial velocity but negatively correlated with the lateral angle. Furthermore, the tangential pull-off force is positively correlated with the normal force and surface energy. In addition, the contact duration of lunar dust particles is positively correlated with their initial velocities, while the residual displacement is negatively correlation. For instance, as the initial velocity increases from 10 to 50 m/s, the maximum elastic–plastic force increases from 37.64 to 321.72 mN. Comparisons of the proposed model with other contact models reveal that the maximum elastic–plastic force of the elastic–plastic triangular pyramid model is only 14.93 % that of the cylindrical model, 34.23 % that of the spherical model, and 76.27 % that of the conical model, indicating significant reductions in the maximum elastic–plastic force owing to the plastic deformations of particles with typical sharp features. Overall, the results of this study offer crucial insights into the mechanical characteristics of nonspherical lunar dust particles under","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":null,"pages":null},"PeriodicalIF":3.1,"publicationDate":"2024-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142534905","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-22DOI: 10.1016/j.actaastro.2024.10.046
Two different diameters of Pt/Al2O3 spherical catalysts (1 mm and 2 mm) for HTP 98 % decomposition were tested to compare the catalytic activity and catalyst ageing. Comparable decomposition performance efficiencies were obtained during thruster-like tests in a catalytic decomposition setup, even though the 1-mm showed a better reactivity and temperature rising time, including in cold-start operation. However, a rapid physical degradation accompanied by pressure peaks observed throughout testing of the 1-mm catalyst led to damage of the catalyst and apparition of fines, causing partial clogging of the bed.
{"title":"Influence of hydrogen peroxide catalyst grain size on performance and ageing","authors":"","doi":"10.1016/j.actaastro.2024.10.046","DOIUrl":"10.1016/j.actaastro.2024.10.046","url":null,"abstract":"<div><div>Two different diameters of Pt/Al<sub>2</sub>O<sub>3</sub> spherical catalysts (1 mm and 2 mm) for HTP 98 % decomposition were tested to compare the catalytic activity and catalyst ageing. Comparable decomposition performance efficiencies were obtained during thruster-like tests in a catalytic decomposition setup, even though the 1-mm showed a better reactivity and temperature rising time, including in cold-start operation. However, a rapid physical degradation accompanied by pressure peaks observed throughout testing of the 1-mm catalyst led to damage of the catalyst and apparition of fines, causing partial clogging of the bed.</div></div>","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":null,"pages":null},"PeriodicalIF":3.1,"publicationDate":"2024-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142538882","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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