Pub Date : 2024-03-01Epub Date: 2022-04-20DOI: 10.1007/s00787-022-01975-y
Erica Mattelin, Kristina Paidar, Natalie Söderlind, Frida Fröberg, Laura Korhonen
The Nordic welfare model is often used as an example for the promotion of health and wellbeing, even in vulnerable groups of children, such as refugees. Nonetheless, there are no published reviews on resilience and/or risk and protective factors for physical and mental health among refugee children living in Nordic countries. In this systematic review, we identified 5181 studies on the topic, screened titles, and abstracts, viewed 632, and finally included 26 studies. These studies described 18 samples with a total of 34,080 individuals ranging in ages 0-18 years. Overall, the studies were of good quality. Nearly all studies assessed adversity. Six studies reported physical health outcomes and all studies mental health outcomes, most often post-traumatic stress disorder and anxiety. None explicitly studied resilience. While we found that age and sex are the most frequently studied risk- and protective factors, findings are inconclusive, since the direction of the associations was different in the different studies. This systematic review indicates that there is still a need for well-designed and -powered studies using clear definitions of key study concepts to examine health outcomes and resilience among refugee children in Nordic countries.
{"title":"A systematic review of studies on resilience and risk and protective factors for health among refugee children in Nordic countries.","authors":"Erica Mattelin, Kristina Paidar, Natalie Söderlind, Frida Fröberg, Laura Korhonen","doi":"10.1007/s00787-022-01975-y","DOIUrl":"10.1007/s00787-022-01975-y","url":null,"abstract":"<p><p>The Nordic welfare model is often used as an example for the promotion of health and wellbeing, even in vulnerable groups of children, such as refugees. Nonetheless, there are no published reviews on resilience and/or risk and protective factors for physical and mental health among refugee children living in Nordic countries. In this systematic review, we identified 5181 studies on the topic, screened titles, and abstracts, viewed 632, and finally included 26 studies. These studies described 18 samples with a total of 34,080 individuals ranging in ages 0-18 years. Overall, the studies were of good quality. Nearly all studies assessed adversity. Six studies reported physical health outcomes and all studies mental health outcomes, most often post-traumatic stress disorder and anxiety. None explicitly studied resilience. While we found that age and sex are the most frequently studied risk- and protective factors, findings are inconclusive, since the direction of the associations was different in the different studies. This systematic review indicates that there is still a need for well-designed and -powered studies using clear definitions of key study concepts to examine health outcomes and resilience among refugee children in Nordic countries.</p>","PeriodicalId":50048,"journal":{"name":"Journal of Spacecraft and Rockets","volume":"54 1","pages":"667-700"},"PeriodicalIF":6.0,"publicationDate":"2024-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10894096/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81797830","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Radioisotope thermoelectric generators (RTGs) have been used as power sources for several space missions, including the multimission RTG (MMRTG) in NASA’s recent Mars Curiosity and Perseverance rovers. The enhanced MMRTG (eMMRTG) design is an MMRTG retrofitted with advanced skutterudite thermoelectric couples to improve efficiency and power output over time. The eMMRTG’s predicted reliability over the mission duration is influenced by the uncertainty in the physics parameters governing its performance. We use a Bayesian approach to account for two types of uncertainty: epistemic and aleatory. The reliability analysis has two steps: 1) uncertainty quantification from experimental data for key physics parameters, and 2) uncertainty propagation through a computational RTG life performance prediction. In particular, we use hierarchical models to separate specimen-to-specimen uncertainty and also to model the separate manufacturing batches of thermoelectric couples loaded into the eMMRTG. We use a secondary probability method to predict reliability with epistemic uncertainty intervals for the eMMRTG system at 10,000 h for which recent data are available. We show how reliability and uncertainty intervals depend on hypothetical power requirements at 10,000 h. The approach is generally applicable when experimental data and computer simulation are used to predict the reliability of a new technology.
{"title":"Bayesian Reliability Analysis of the Enhanced Multimission Radioisotope Thermoelectric Generator","authors":"Chung H. Lee, Thierry Caillat, S. Pinkowski","doi":"10.2514/1.a35785","DOIUrl":"https://doi.org/10.2514/1.a35785","url":null,"abstract":"Radioisotope thermoelectric generators (RTGs) have been used as power sources for several space missions, including the multimission RTG (MMRTG) in NASA’s recent Mars Curiosity and Perseverance rovers. The enhanced MMRTG (eMMRTG) design is an MMRTG retrofitted with advanced skutterudite thermoelectric couples to improve efficiency and power output over time. The eMMRTG’s predicted reliability over the mission duration is influenced by the uncertainty in the physics parameters governing its performance. We use a Bayesian approach to account for two types of uncertainty: epistemic and aleatory. The reliability analysis has two steps: 1) uncertainty quantification from experimental data for key physics parameters, and 2) uncertainty propagation through a computational RTG life performance prediction. In particular, we use hierarchical models to separate specimen-to-specimen uncertainty and also to model the separate manufacturing batches of thermoelectric couples loaded into the eMMRTG. We use a secondary probability method to predict reliability with epistemic uncertainty intervals for the eMMRTG system at 10,000 h for which recent data are available. We show how reliability and uncertainty intervals depend on hypothetical power requirements at 10,000 h. The approach is generally applicable when experimental data and computer simulation are used to predict the reliability of a new technology.","PeriodicalId":50048,"journal":{"name":"Journal of Spacecraft and Rockets","volume":"122 8","pages":""},"PeriodicalIF":1.6,"publicationDate":"2024-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139390804","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Family of Relative Drifts: A Practical Alternative to Design Relative Orbits","authors":"Ao Shen, Lincheng Li, Jingrui Zhang, Ming Xu","doi":"10.2514/1.a35810","DOIUrl":"https://doi.org/10.2514/1.a35810","url":null,"abstract":"","PeriodicalId":50048,"journal":{"name":"Journal of Spacecraft and Rockets","volume":"93 3","pages":""},"PeriodicalIF":1.6,"publicationDate":"2023-12-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139145715","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
C. Zeng, Grant R. Hecht, Souma Chowdhury, E. M. Botta
Tether-nets deployed from a chaser spacecraft are a promising solution to capturing space debris. The success of the one-shot capture process depends on the net’s structural dynamic properties, attributed to its physical design, and on the ability to perform an optimal launch and closure subject to sensing and actuation uncertainties. Hence, this paper presents a reliability-based optimization framework to simultaneously optimize the net design and its launch and closing actions to minimize the system mass (case 1) or closing time (case 2) while preserving a specified probability of capture success. Success is assessed in terms of a capture quality index and the number of locked node pairs. Gaussian noise is used to model the uncertainties in the dynamics, state estimation, and actuation of the tether-net, which is propagated via Monte Carlo sampling. To account for uncertainties and ensure computational efficiency, given the cost of simulating the tether-net dynamics, Bayesian optimization is used to solve this problem. Optimization results show that the mission success rate in the presence of uncertainties has increased from 75% to over 98%, while the capture completion time has almost halved.
{"title":"Concurrent Design Optimization of Tether-Net System and Actions for Reliable Space-Debris Capture","authors":"C. Zeng, Grant R. Hecht, Souma Chowdhury, E. M. Botta","doi":"10.2514/1.a35812","DOIUrl":"https://doi.org/10.2514/1.a35812","url":null,"abstract":"Tether-nets deployed from a chaser spacecraft are a promising solution to capturing space debris. The success of the one-shot capture process depends on the net’s structural dynamic properties, attributed to its physical design, and on the ability to perform an optimal launch and closure subject to sensing and actuation uncertainties. Hence, this paper presents a reliability-based optimization framework to simultaneously optimize the net design and its launch and closing actions to minimize the system mass (case 1) or closing time (case 2) while preserving a specified probability of capture success. Success is assessed in terms of a capture quality index and the number of locked node pairs. Gaussian noise is used to model the uncertainties in the dynamics, state estimation, and actuation of the tether-net, which is propagated via Monte Carlo sampling. To account for uncertainties and ensure computational efficiency, given the cost of simulating the tether-net dynamics, Bayesian optimization is used to solve this problem. Optimization results show that the mission success rate in the presence of uncertainties has increased from 75% to over 98%, while the capture completion time has almost halved.","PeriodicalId":50048,"journal":{"name":"Journal of Spacecraft and Rockets","volume":" 21","pages":""},"PeriodicalIF":1.6,"publicationDate":"2023-12-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139144936","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Derek J. Dalle, Stuart E. Rogers, Jamie G. Meeroff, Aaron C. Burkhead, D. Schauerhamer, Joshua F. Diaz
This paper will discuss the use of computational fluid dynamics (CFD) for the Space Launch System (SLS) program to model the ascent phase of flight. The ascent phase begins shortly after the vehicle clears the launch tower and extends to the first staging event. To model SLS’s ascent, over 1000 numerical solutions of the Navier–Stokes equations were solved, and this analysis has been repeated for five different SLS configurations. To manage this demanding ascent CFD task, the SLS program has developed the Computational Aerosciences Productivity & Execution software. The paper also discusses some of the ways that CFD and high-end computing have advanced in the last decade and offers some comparisons to CFD used in the Space Shuttle Program.
{"title":"Launch Vehicle Ascent Computational Fluid Dynamics for the Space Launch System","authors":"Derek J. Dalle, Stuart E. Rogers, Jamie G. Meeroff, Aaron C. Burkhead, D. Schauerhamer, Joshua F. Diaz","doi":"10.2514/1.a35809","DOIUrl":"https://doi.org/10.2514/1.a35809","url":null,"abstract":"This paper will discuss the use of computational fluid dynamics (CFD) for the Space Launch System (SLS) program to model the ascent phase of flight. The ascent phase begins shortly after the vehicle clears the launch tower and extends to the first staging event. To model SLS’s ascent, over 1000 numerical solutions of the Navier–Stokes equations were solved, and this analysis has been repeated for five different SLS configurations. To manage this demanding ascent CFD task, the SLS program has developed the Computational Aerosciences Productivity & Execution software. The paper also discusses some of the ways that CFD and high-end computing have advanced in the last decade and offers some comparisons to CFD used in the Space Shuttle Program.","PeriodicalId":50048,"journal":{"name":"Journal of Spacecraft and Rockets","volume":"54 4","pages":""},"PeriodicalIF":1.6,"publicationDate":"2023-12-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139146602","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Tyler D Stoffel, C. Karlgaard, Todd R. White, Thomas K. West
On February 18th, 2021, the Mars 2020 entry system successfully delivered the Perseverance rover to the surface of Mars at Jezero Crater. The entry capsule carried instrumentation installed on the heatshield and backshell, named “Mars Entry, Descent, and Landing Instrumentation 2.” The instruments were used to measure the aerodynamic and aerothermodynamic performance of the entry vehicle. Five sensors at two locations (three sensors at one location and two sensors at the second location), including a thermocouple plug, heat flux gauge, and a radiometer, were co-located on the backshell. The sensors were exposed to roughly the same aerodynamic heating but measured these environments in different ways, each with its own set of modeling and measurement error complications. This paper develops a method for blending each of these measurements together in a single algorithm to produce estimates of the aerothermodynamic environments at each backshell location. The approach makes use of the Kalman–Schmidt filter/smoother methodology, where systematic measurement error parameters are modeled as multiplicative states that are estimated by the filter along with the aerothermal states. The results of the sensor fusion approach are expected to be used to inform and improve aerothermal modeling for future Mars entry capsules.
{"title":"Fusion of In-Flight Aerothermodynamic Heating Sensor Measurements Using Kalman Filtering","authors":"Tyler D Stoffel, C. Karlgaard, Todd R. White, Thomas K. West","doi":"10.2514/1.a35641","DOIUrl":"https://doi.org/10.2514/1.a35641","url":null,"abstract":"On February 18th, 2021, the Mars 2020 entry system successfully delivered the Perseverance rover to the surface of Mars at Jezero Crater. The entry capsule carried instrumentation installed on the heatshield and backshell, named “Mars Entry, Descent, and Landing Instrumentation 2.” The instruments were used to measure the aerodynamic and aerothermodynamic performance of the entry vehicle. Five sensors at two locations (three sensors at one location and two sensors at the second location), including a thermocouple plug, heat flux gauge, and a radiometer, were co-located on the backshell. The sensors were exposed to roughly the same aerodynamic heating but measured these environments in different ways, each with its own set of modeling and measurement error complications. This paper develops a method for blending each of these measurements together in a single algorithm to produce estimates of the aerothermodynamic environments at each backshell location. The approach makes use of the Kalman–Schmidt filter/smoother methodology, where systematic measurement error parameters are modeled as multiplicative states that are estimated by the filter along with the aerothermal states. The results of the sensor fusion approach are expected to be used to inform and improve aerothermal modeling for future Mars entry capsules.","PeriodicalId":50048,"journal":{"name":"Journal of Spacecraft and Rockets","volume":" 21","pages":""},"PeriodicalIF":1.6,"publicationDate":"2023-12-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139145234","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Clarification: Seeded Hydrogen in Nuclear Thermal Propulsion Engines","authors":"Dennis Nikitaev, L. Thomas","doi":"10.2514/1.a34711.c1","DOIUrl":"https://doi.org/10.2514/1.a34711.c1","url":null,"abstract":"","PeriodicalId":50048,"journal":{"name":"Journal of Spacecraft and Rockets","volume":"17 3","pages":""},"PeriodicalIF":1.6,"publicationDate":"2023-12-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139147396","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Grace Vincent, I. R. Ward, Charles Moore, Jingdao Chen, Kai Pak, Alice Yepremyan, Brian Wilson, Edwin Y. Goh
Current deep-learning models employed by the planetary science community are constrained by a dearth of annotated training data for planetary images. Current models also frequently suffer from inductive bias due to domain shifts when using the same model on data obtained from different spacecraft or different time periods. Moreover, power and compute constraints preclude state-of-the-art vision models from being implemented on robotic spacecraft. In this research, we propose a self-supervised learning (SSL) framework that leverages contrastive learning techniques to improve upon state-of-the-art performance on several published Mars computer vision benchmarks. Our SSL framework enables models to be trained using fewer labels, generalize well to different tasks, and achieve higher computational efficiency. Results on published Mars computer vision benchmarks show that contrastive pretraining outperforms plain supervised learning by 2–10%. We further investigate the importance of dataset heterogeneity in mixed-domain contrastive pretraining. Using self-supervised distillation, we were also able to train a compact ResNet-18 student model to achieve better accuracy than its ResNet-152 teacher model while having 5.2 times fewer parameters. We expect that these SSL techniques will be relevant to the planning of future robotic missions, and remote sensing identification of target destinations with high scientific value.
{"title":"CLOVER: Contrastive Learning for Onboard Vision-Enabled Robotics","authors":"Grace Vincent, I. R. Ward, Charles Moore, Jingdao Chen, Kai Pak, Alice Yepremyan, Brian Wilson, Edwin Y. Goh","doi":"10.2514/1.a35767","DOIUrl":"https://doi.org/10.2514/1.a35767","url":null,"abstract":"Current deep-learning models employed by the planetary science community are constrained by a dearth of annotated training data for planetary images. Current models also frequently suffer from inductive bias due to domain shifts when using the same model on data obtained from different spacecraft or different time periods. Moreover, power and compute constraints preclude state-of-the-art vision models from being implemented on robotic spacecraft. In this research, we propose a self-supervised learning (SSL) framework that leverages contrastive learning techniques to improve upon state-of-the-art performance on several published Mars computer vision benchmarks. Our SSL framework enables models to be trained using fewer labels, generalize well to different tasks, and achieve higher computational efficiency. Results on published Mars computer vision benchmarks show that contrastive pretraining outperforms plain supervised learning by 2–10%. We further investigate the importance of dataset heterogeneity in mixed-domain contrastive pretraining. Using self-supervised distillation, we were also able to train a compact ResNet-18 student model to achieve better accuracy than its ResNet-152 teacher model while having 5.2 times fewer parameters. We expect that these SSL techniques will be relevant to the planning of future robotic missions, and remote sensing identification of target destinations with high scientific value.","PeriodicalId":50048,"journal":{"name":"Journal of Spacecraft and Rockets","volume":"24 36","pages":""},"PeriodicalIF":1.6,"publicationDate":"2023-12-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139147843","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Clarification: Seeded Hydrogen in Mars Transfer Vehicles Using Nuclear Thermal Propulsion Engines","authors":"Dennis Nikitaev, L. Thomas","doi":"10.2514/1.a34722.c1","DOIUrl":"https://doi.org/10.2514/1.a34722.c1","url":null,"abstract":"","PeriodicalId":50048,"journal":{"name":"Journal of Spacecraft and Rockets","volume":" 43","pages":""},"PeriodicalIF":1.6,"publicationDate":"2023-12-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139143772","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Clarification: Impacts of In-Situ Alternative Propellant on Nuclear Thermal Propulsion Mars Vehicle Architectures","authors":"Dennis Nikitaev, L. Thomas","doi":"10.2514/1.a35399.c1","DOIUrl":"https://doi.org/10.2514/1.a35399.c1","url":null,"abstract":"","PeriodicalId":50048,"journal":{"name":"Journal of Spacecraft and Rockets","volume":" 42","pages":""},"PeriodicalIF":1.6,"publicationDate":"2023-12-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139143935","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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