Acta Astronautica最新文献

{"title":"Hypervelocity perforation of thin films applicable to debris detection in Low Earth Orbit","authors":"M.J. Burchell,&nbsp;L.A. Alesbrook,&nbsp;M. van Ginneken,&nbsp;P.J. Wozniakiewicz","doi":"10.1016/j.actaastro.2026.01.050","DOIUrl":"10.1016/j.actaastro.2026.01.050","url":null,"abstract":"<div><div>The growth in the number of satellites in Low Earth Orbit, coupled with the possibility of their catastrophic disruption, may lead to more orbital debris, which in turn has increased the risk of damage to spacecraft arising from impacts by small pieces of debris. There is thus an urgent need to monitor the small particle population in Low Earth Orbit, using a new generation of dust detectors. Various designs are in preparation, and several use the principle of observing particles via their impact penetration of thin films. Previously, most laboratory studies of penetration of thin films have used spherical impactors for ease. However, these are not representative of the shapes of orbital debris. Accordingly, here, impacts are reported at 5 km s⁻¹, by various shaped projectiles (sizes typically 0.5–2 mm) on thin (12.5 μm thick) Kapton films. The shapes used were spheres, rods, cubes and platelets, and represent a selection of the shapes present in the orbital debris population that arises from catastrophic disruption of spacecraft. The size and shape of the holes in the Kapton arising from the impacts, are shown to reflect the size and cross-sectional area of an impactor as it passes through the film; even the presence of angular corners in the impactors can be seen in the holes. However, due to the variable aspect of an individual impactor presented to the film during an impact, identification of the exact 3-dimensional shape cannot be obtained from the 2-dimensional hole. Nevertheless, with minor exceptions it is possible to separate more spherical (i.e., natural dust) impactors from the other shapes (i.e. variously shaped anthropogenic debris).</div></div>","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":"243 ","pages":"Pages 73-90"},"PeriodicalIF":3.4,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146033457","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}

{"title":"Spacecraft pursuit-evasion game with incomplete information: A pre-training approximate dynamic programming method","authors":"Jiancheng Zhang,&nbsp;Yidi Wang,&nbsp;Wei Zheng,&nbsp;Meijiao Zhao","doi":"10.1016/j.actaastro.2026.01.071","DOIUrl":"10.1016/j.actaastro.2026.01.071","url":null,"abstract":"<div><div>This paper investigates a synchronous near-optimal control strategy for continuous-time spacecraft pursuit-evasion (PE) games subject to actuator saturation and incomplete information regarding the evader’s control weights. First, the evader’s unknown control weight parameters are identified online using a saturation-aware estimator, enabling real-time information acquisition by the pursuer. Second, to compute the synchronous control laws, a pre-training approximate dynamic programming (ADP) framework is proposed, which integrates offline neural network-based (NN-based) value function initialization with online iterative correction to approximately solve the Hamilton–Jacobi–Isaacs (HJI) equation. Furthermore, the sufficient conditions for the uniform ultimate boundedness (UUB) of the PE game system are analyzed via Lyapunov analysis. Finally, numerical simulations validate the effectiveness and robustness of the proposed method.</div></div>","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":"243 ","pages":"Pages 251-262"},"PeriodicalIF":3.4,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146109805","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}

{"title":"Star image motion deblurring via angular velocity assisted U-Net with feature fusion and CBAM","authors":"Chenran Li ,&nbsp;Xu Yan ,&nbsp;Hang Yang ,&nbsp;Dingjie Wang ,&nbsp;Hongbo Zhang ,&nbsp;Weimin Bao","doi":"10.1016/j.actaastro.2026.01.041","DOIUrl":"10.1016/j.actaastro.2026.01.041","url":null,"abstract":"<div><div>For star sensors operating in space, star images are susceptible to blur degradation caused by complicated motions, leading to difficulties in star identification and reduced accuracy in star spots extraction. Although deep learning methods have been applied to mitigate these issues, their performance is often limited by the neglect of physical motion information. To address this, we embed angular velocity data to guide the network in establishing the relationship between angular velocity and blur parameters. Furthermore, considering the sparse nature of star spot features, we introduce the Convolutional Block Attention Module (CBAM) to enhance the feature saliency of star regions and their motion trajectories. A dedicated feature fusion module is also designed to effectively integrate inertial data and visual representations, facilitating joint learning of physical motion patterns and image features. Simulation experiments indicate that the proposed method significantly improves image restoration quality compared to the baseline U-Net, achieving a 16.84 % increase in PSNR and reducing the centroid error to 0.0836 pixels. Experiments based on in-orbit observation data validate the effectiveness of our method in real-world scenarios.</div></div>","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":"243 ","pages":"Pages 358-370"},"PeriodicalIF":3.4,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146014780","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}

{"title":"Reconstruction of in-orbit breakup events over the short term","authors":"Francesca Ottoboni,&nbsp;Andrea Muciaccia,&nbsp;Camilla Colombo","doi":"10.1016/j.actaastro.2026.01.061","DOIUrl":"10.1016/j.actaastro.2026.01.061","url":null,"abstract":"<div><div>The massive growth of space activities over the past decades has lead to an increase of the space debris population, which is threatening the safety of space operations and active satellites. Several fragmentation events caused by catastrophic collisions and explosions have single-handedly contributed to the increase in the number of space debris, highlighting the importance of the reconstruction of such events to gain insight on the breakups and decrease the collision risk they cause to active satellites.</div><div>This work proposes a fragmentation reconstruction approach for this purpose, which combines pruning and clustering criteria with a backward propagation to identify the epoch of the fragmentation and the involved objects. The model was tested by using publicly available Two-Line-Elements data. The problem of the unreliability of such data is addressed by modifying the original approach to account for uncertainty, multiplying the original Two-Line-Elements data and choosing the optimal set of objects for the reconstruction. The optimal values of the pruning filters thresholds for the method are also investigated to identify the most effective criteria. Moreover, the reciprocal influence of the filters is assessed through a sensitivity analysis. The proposed approach is applied to two real fragmentation events to compare the accuracy of the reconstruction with and without the uncertainty quantification. The method proves to be effective in the evaluation of the epoch of the breakup as well as the identification of the fragments and their parent.</div></div>","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":"243 ","pages":"Pages 326-337"},"PeriodicalIF":3.4,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146174653","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}

{"title":"“Getting things done” or “Doing the right things”? Micro-foundations of product-service strategies in Earth Observation","authors":"Valentina Zancan,&nbsp;Paolo Trucco,&nbsp;Giorgio Locatelli","doi":"10.1016/j.actaastro.2026.01.040","DOIUrl":"10.1016/j.actaastro.2026.01.040","url":null,"abstract":"<div><div>The space sector is transitioning from an infrastructure-driven legacy paradigm toward a commercially driven New Space paradigm. Historically characterized by high barriers to entry and demand anchored on institutional needs, the sector now faces competitive pricing, rapid technological change, and expanding commercial use cases that reshape the design and development of space assets. The Earth Observation (EO) segment exemplifies this transition, as the growing commoditization of EO data led to new development logics and organizational practices. Similar to other sectors experiencing rapid change, this transition is not without challenges. A central challenge for legacy EO organizations lies in reconfiguring the processes, organizational structures, and decision rules, i.e. the “micro-foundations”, that govern EO solution development. Understanding how to reconfigure such micro-foundations is of practical importance for operating within the current New Space paradigm, yet it is an under-researched perspective for space organizations. Drawing on product-service system development and Operations Management literature, this study investigates how micro-foundations shape EO solution development strategies in legacy and New Space contexts. Using a multiple-case study based on semi-structured interviews and secondary data, we build on the Decoupling Point (DP) concept from operations management and propose an EO DP strategy conceptual framework. This framework explains how and where customer and user requirements enter the EO value chain and influence design and development activities, and how DP positioning revolves across organizational boundaries and inter-organizational settings. Our findings indicate that legacy space organizations adopt downstream DP strategies, in which user needs influence EO solution development mainly at later stages, reinforcing technology-push logics and limited integration of commercial needs. Conversely, New Space organizations employ dynamic DP strategies that combine customization, modularity, and standardization, enabling user needs to shape upstream design and development decisions. Importantly, we find that DP positioning in New Space organizations is not confined within firm boundaries but increasingly emerges through inter-organizational collaborations. This study contributes to research on the Space Economy by offering a fine-grained, micro-foundational explanation of diverse EO solution development strategies and their evolution. For practitioners and policymakers, the findings highlight multiple pathways for legacy organizations to maintain relevance in an evolving EO market without undermining their core capabilities and heritage.</div></div>","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":"243 ","pages":"Pages 263-279"},"PeriodicalIF":3.4,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146033432","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}

{"title":"Feasibility-guaranteed analytical mars landing guidance in hazardous terrains with disturbances","authors":"Yan Wang ,&nbsp;Yaxuan Li ,&nbsp;Xinfu Liu","doi":"10.1016/j.actaastro.2026.01.053","DOIUrl":"10.1016/j.actaastro.2026.01.053","url":null,"abstract":"<div><div>This paper investigates the Mars landing guidance problem in hazardous terrains. Disturbances during landing, including parameter uncertainties and external forces, may cause the guidance problem infeasible, preventing the lander from avoiding the terrains. To ensure a safe landing, it is crucial, though challenging, to maintain the recursive feasibility of the guidance problem in each guidance cycle. To this end, we propose a two-phase guidance framework, where recursive feasibility is considered only in the first phase and the terminal constraints in this phase are significantly relaxed. This turns the recursive feasibility requirement into the assured satisfaction of the terrain avoidance constraint under disturbances in each guidance cycle. The main contribution of this work lies in analytically deriving a feasible control set and proving that, as long as the control command is within this set, the state at the next guidance cycle must be able to reach the required terminal state while satisfying the terrain avoidance constraint. This guarantees the recursive feasibility of the guidance problem, provided it is feasible in the initial time. As a result, guidance commands in the first phase can be generated by the well-known ZEM/ZEV guidance law, and then simply saturated by the derived feasible control set. In the second phase, the terrain avoidance constraint no longer needs to be considered and the ZEM/ZEV guidance law is applied to drive the lander to the desired location with a safe touchdown velocity. Numerical examples demonstrate that the proposed method can ensure recursive feasibility of the guidance problem under disturbances and is capable of achieving meter-level landing accuracy.</div></div>","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":"243 ","pages":"Pages 1-13"},"PeriodicalIF":3.4,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146033441","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}

{"title":"Numerical simulation of water migration in lunar soil based on the Monte Carlo model","authors":"Yan Zhang ,&nbsp;Yongjun Wang ,&nbsp;Jin Wang ,&nbsp;Chengdan He ,&nbsp;Wenfeng Li ,&nbsp;Huzhong Zhang ,&nbsp;Yasheng Li ,&nbsp;Detian Li","doi":"10.1016/j.actaastro.2026.01.067","DOIUrl":"10.1016/j.actaastro.2026.01.067","url":null,"abstract":"<div><div>This study proposes a geometric model based on the Monte Carlo method to enable precise characterization of porous media structures in lunar soil and validates its reliability by numerically reconstructing experimental investigations into the effects of adsorption behavior on water migration at −100 °C. Based on this model, the prolonging effect of the regolith on ice retention time was quantitatively analyzed, and the influence mechanisms of key parameters such as temperature, thickness, and specific surface area were systematically elucidated. The study indicates that the particle size distribution of lunar soil can be described by a unified cumulative probability distribution, and the reconstruction model based on the Monte Carlo method can effectively characterize pore structure features. The time required for the regolith to achieve saturated adsorption shows a linear dependence on its thickness. The additional retention time of water ice is most sensitive to temperature variations. At temperatures not exceeding 110 K, even a regolith layer thinner than 1 m can extend the preservation of water ice by several hundred million years. However, once the temperature exceeds 110 K, the protective capacity of the overlying layer declines exponentially within the narrow temperature range of 110 K–120 K. In warmer lunar regions, the regolith's capacity to retain water ice is limited. Even deeply buried water ice will gradually dissipate over extended geological timescales. Based on the mechanisms described above, this study suggests that in permanently shadowed regions with temperatures below 110 K, water ice may be detectable within the uppermost 1 m of the regolith. In contrast, in regions with temperatures ranging from 120 K to 140 K, the required detection depth may extend to tens of meters. This study provides a theoretical foundation for understanding the distribution and preservation mechanisms of water ice on the lunar surface. The methodologies developed and the conclusions drawn provide valuable scientific insights for future in-situ detection missions targeting lunar polar regions.</div></div>","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":"243 ","pages":"Pages 189-201"},"PeriodicalIF":3.4,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146072617","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}

{"title":"Orbit determination and prediction for uncooperative spacecrafts with continuous low-thrust maneuver via piecewise estimation","authors":"Liu Yuan ,&nbsp;Bin Li ,&nbsp;Xin Tian ,&nbsp;Wei Liang ,&nbsp;Peng Lv ,&nbsp;Jizhang Sang","doi":"10.1016/j.actaastro.2026.01.033","DOIUrl":"10.1016/j.actaastro.2026.01.033","url":null,"abstract":"<div><div>The exponential growth of mega-constellation satellites, typified by SpaceX’s Starlink, poses unprecedented challenges for existing space surveillance, particularly when tracking uncooperative spacecrafts executing continuous orbit-raising/deorbiting maneuvers. This situation makes the conventional orbit determination (OD) and prediction (OP) struggle with three critical issues: insufficient observational data, unknown maneuvering parameters, and the cumulative effects of unmodeled thrust. To address these issues, this study proposes a piecewise estimation-based OD method by developing a semi-analytical thrust acceleration (TA) model. The TA model employs time-explicit polynomial expansions with state-dependent coefficients to characterize the continuous low-thrust effect. The OD system integrates a piecewise least-squares estimation algorithm with dynamic compensation, enabling accurate TA resolution within one-day observation windows. Specifically, the OP system incorporates the latest TA estimate to account for the future continuous low-thrust effect. Experiments with sparse radar observations of Starlink satellites demonstrate the effectiveness of the proposed method. The TA estimation errors remain below 0.5% relative to the reference obtained from precise ephemerides. The OP capabilities maintain one-day and two-day position accuracy below 2 and 4 km, respectively, improving by more than 60% compared to the unified OD method. More importantly, the approach exhibits operational robustness, achieving OD convergence with initial TA errors up to 35%. These advantages make the proposed approach a practicable solution for autonomous catalog maintenance of maneuvering spacecraft.</div></div>","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":"243 ","pages":"Pages 99-111"},"PeriodicalIF":3.4,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146033433","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}

{"title":"Galerkin lie group variational integrators developed for orbit-attitude coupled dynamics near small celestial bodies","authors":"Jinah Lee,&nbsp;Chandeok Park","doi":"10.1016/j.actaastro.2026.01.052","DOIUrl":"10.1016/j.actaastro.2026.01.052","url":null,"abstract":"<div><div>This research presents a Galerkin Lie group variational integrator on <span><math><mrow><msup><mi>R</mi><mn>3</mn></msup><mo>×</mo><msup><mi>S</mi><mn>3</mn></msup></mrow></math></span> designed for analyzing the orbit–attitude coupled motions of spacecraft operating near small celestial bodies. Two primary objectives lie in constructing the proposed integrator: to preserve both the Lie group and Hamiltonian structures, and to achieve precise propagation comparable to conventional vector-based methods. This study analytically derives the partial derivatives of the rigid-body potential with respect to state variables and incorporates them into the discrete Lagrangian formulation to facilitate the integration process. The proposed integrator supports general gravity models of small celestial bodies. Example applications using both the point mass and spherical harmonics models are presented. Numerical simulations verify that the proposed integrator not only maintains geometric structure but also yields high accuracy in propagation, demonstrating its effectiveness for long-term simulations in the vicinity of small celestial bodies. For instance, the proposed integrator achieves an energy-conservation error on the order of <span><math><mrow><msup><mn>10</mn><mrow><mo>−</mo><mn>11</mn></mrow></msup><mo>−</mo><msup><mn>10</mn><mrow><mo>−</mo><mn>8</mn></mrow></msup></mrow></math></span> % of the initial total energy, regardless of the initial state, whereas the error of the vector-based integrator varies over a wider range of <span><math><mrow><msup><mn>10</mn><mrow><mo>−</mo><mn>12</mn></mrow></msup><mo>−</mo><msup><mn>10</mn><mrow><mo>−</mo><mn>4</mn></mrow></msup></mrow></math></span> %.</div></div>","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":"243 ","pages":"Pages 220-236"},"PeriodicalIF":3.4,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146033442","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}

{"title":"A unified framework for compliant control and trajectory planning in robotic in-orbit assembly","authors":"Qiming Ren ,&nbsp;Minghe Shan","doi":"10.1016/j.actaastro.2026.01.029","DOIUrl":"10.1016/j.actaastro.2026.01.029","url":null,"abstract":"<div><div>Robotic In-Orbit Assembly (R-IOA) is a key technology for the construction of large-scale space infrastructure. A significant challenge in this field is the precise docking of modular components, particularly those with complex interfaces. To address this, safety must be considered at both the control and planning levels. At the control level, traditional compliant control strategies show poor adaptability to complex contact and often face challenges in explicitly enforcing physical limitations, such as joint position and torque bounds. Furthermore, while compliant control can effectively manage steady-state contact forces, it is fundamentally limited in mitigating the initial transient impact. This peak force is predominantly determined by the pre-impact velocity, a parameter dictated by the trajectory planner. Conventional planners, however, often generate dynamically infeasible trajectories using decoupled methods that violate the kinematic consistency of rigid-body motion, and they are generally limited in their ability to strictly enforce velocity constraints. To address these dual challenges through an integrated approach, this paper proposes a unified safety framework. This framework combines comprehensive enhancements at both the planning and control layers. At the planning level, a time-optimal trajectory generator operating on the SE(3) manifold produces motions that are dynamically feasible by construction. This ensures that velocity constraints are strictly enforced to proactively minimize impact forces and that the trajectory respects the natural kinematics of rigid-body motion. At the control level, we introduce a Hierarchical Quadratic Programming based Adaptive Controller (HQP-AC). It reformulates compliant interaction as a constrained optimization problem to guarantee the strict enforcement of all hardware safety limits while adaptively managing the steady-state interaction. The effectiveness of the proposed approach was demonstrated through simulations of a representative docking scenario. Compared to a classical impedance controller with decoupled trajectory planning, the proposed framework reduces peak axial contact forces by 49% and steady-state contact forces by 30%, and successfully prevents the catastrophic joint limit violations observed in the baseline method. Furthermore, it achieves a final lateral position error of 0.18<!--> <!-->mm and an orientation error of 1.08°, representing a significant improvement in docking accuracy.</div></div>","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":"243 ","pages":"Pages 32-45"},"PeriodicalIF":3.4,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146033440","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}