Journal of Space Safety Engineering最新文献

{"title":"Reducing reentry casualty risk for spacecraft on long-term reentering eccentric inclined geosynchronous (Tundra) disposal orbits","authors":"K. Rolf Bohman,&nbsp;Michael A. Weaver,&nbsp;Alan B. Jenkin,&nbsp;John P. McVey","doi":"10.1016/j.jsse.2024.08.008","DOIUrl":"10.1016/j.jsse.2024.08.008","url":null,"abstract":"<div><div>This paper considers disposal of spacecraft and upper stages on eccentric inclined geosynchronous orbits (eccentric IGSOs), specifically the class known as Tundra orbits. The U.S. Government Orbital Debris Mitigation Standard Practices (ODMSP) released in December 2019 include a disposal option to use orbital eccentricity growth for long-term reentry within 200 years that could be used for Tundra orbits. A condition of this disposal option is that reentry casualty risk be limited. An analysis was performed to assess reentry casualty risk for a generic Tundra spacecraft and typical upper stages on Tundra disposal orbits. From propagation sweeps accounting for eccentricity growth of Tundra disposal orbits, several Tundra disposal orbit cases were selected for reentry analysis. A reentry risk analysis for these cases assuming reentry from near-circular orbits was performed. Results show that predicted casualty risk for the generic Tundra spacecraft and typical upper stages well exceed allowable risk limits in the ODMSP. An analysis of reentry from the selected Tundra disposal orbits accounting for the high eccentricity due to eccentricity growth just before reentry was then performed. Results show that the distribution of reentry points on the Earth can be concentrated over ocean in the southern hemisphere where there is less human population. The generic Tundra spacecraft and one of the upper stages considered were then found to be compliant with the limit of 1 in 10,000 expected casualties in the ODMSP. These results indicate promise for wider usage of the long-term re-entry option in the ODMSP.</div></div>","PeriodicalId":37283,"journal":{"name":"Journal of Space Safety Engineering","volume":"11 3","pages":"Pages 481-490"},"PeriodicalIF":1.0,"publicationDate":"2024-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142571563","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Synthetic orbit uncertainty generation through regression analysis of historical Conjunction Data Messages","authors":"Andrea Zollo ,&nbsp;Giuseppe Di Campli Bayard de Volo ,&nbsp;Martin Weigel ,&nbsp;Saika Aida ,&nbsp;Ralph Kahle ,&nbsp;Juan Félix San Juan Díaz","doi":"10.1016/j.jsse.2024.06.001","DOIUrl":"10.1016/j.jsse.2024.06.001","url":null,"abstract":"<div><div>In the last decades, the Earth-orbiting population of both active and non-active objects has grown significantly, leading to a substantial increase in number of possible in-orbit collisions. It is therefore crucial to monitor the orbit of space resident objects to assess in advance the threat of risky conjunctions. Within this framework, the 18th Space Defense Squadron (SDS) is consistently updating the orbit of thousands of tracked objects by processing observations of the U.S. Space Surveillance Network (SSN). The determined orbital data is continuously maintained in the Special Perturbation (SP) catalogue and used by the 19th SDS to issue close approach warnings to satellite operators around the globe in the form of Conjunction Data Messages (CDM). The Flight Dynamics (FD) group of the German Space Operation Centre (GSOC) receives on regular basis a subset of the SP catalogue data along with CDMs associated to the fleet of its controlled satellites. The SP ephemerides are in fact provided without any covariance information preventing any computation of the Probability of Collision (Pc). In GSOC FD we are implementing a service to link a series of synthetic orbital error covariance matrices to a given SP ephemeris by statistically analyzing historical CDMs of past events. More than 30 GB of past conjunction data are processed to extract state vector, covariance matrix and object size parameter of already encountered secondary objects. The orbital errors of these last are subsequently categorized and divided into orbital classes to decouple the high correlation the covariance has with respect to solar flux, object dimension, altitude of perigee, eccentricity and orbit inclination. The classification aims at collecting similar CDMs regarding the aforementioned dependencies, and approximates the predicted 1-sigma position errors in the orbital frame by optimal curve-fitting techniques. By evaluation of the curve fitting coefficients of a requested orbit class a covariance matrix can be generated for any prediction time in upcoming CDM refinements and other analyses. The work discusses the limiting cases of the classification approach, bringing possible solutions to the scenario of empty classes. An in-depth characterization of the parameters that affect the orbital errors is in fact performed to individualize the neighboring class that provides the closest and most meaningful covariance timeline. Successively, the effect of using synthetic covariance in a conjunction risk assessment is also explored, adapting the problem on real operations. Lastly, the entire data processing pipeline and how the described service fits into the GSOC Flight Dynamics System (FDS) framework is described.</div></div>","PeriodicalId":37283,"journal":{"name":"Journal of Space Safety Engineering","volume":"11 3","pages":"Pages 454-461"},"PeriodicalIF":1.0,"publicationDate":"2024-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142571561","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Introducing Space Debris: Update to the State of the Art","authors":"José Pedro Ferreira ,&nbsp;Daniel Moomey ,&nbsp;Chris L. Ostrom","doi":"10.1016/j.jsse.2024.09.001","DOIUrl":"10.1016/j.jsse.2024.09.001","url":null,"abstract":"","PeriodicalId":37283,"journal":{"name":"Journal of Space Safety Engineering","volume":"11 3","pages":"Page 387"},"PeriodicalIF":1.0,"publicationDate":"2024-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142571637","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Establishing requirements for lunar and cislunar orbital debris tracking","authors":"Brad F. Barakat,&nbsp;Michael T. Kezirian","doi":"10.1016/j.jsse.2024.08.006","DOIUrl":"10.1016/j.jsse.2024.08.006","url":null,"abstract":"<div><div>There is a need to formally coordinate lunar and cislunar space traffic management to mitigate the risk of collisions with micrometeoroids and orbital debris in this space domain. To control this hazard, it will be critical to develop a high-fidelity orbital debris catalog. This catalog will be maintained by monitoring and propagating the trajectory of objects. The need to perform a debris avoidance maneuver for collision avoidance will depend on the fidelity of the propagated debris trajectory. A larger uncertainty (magnitude as a function of time) will require a larger maneuver and a higher likelihood of the need to perform this maneuver. This study assesses debris avoidance maneuvers and corresponding corrective actions to recover the desired mission trajectory as a way to evaluate the desired capability of tracking of objects in lunar and cislunar orbit. The baseline Earth-to-Moon trajectory was that of the Artemis I mission. Typical conjunction assessments were postulated at 100,000 km from Earth's center (approximately a quarter of the way to the moon) and at lunar orbit insertion (LOI). For these two cases, the required debris avoidance maneuver (and hence impact to the mission) is tied to the uncertainty in orbital debris tracking. The study provides a methodology and baseline inputs to establish future requirements of debris tracking in lunar and cislunar orbits. It also reinforces the importance of long-term sustainability for lunar missions, specifically preventing the generation of orbital debris.</div></div>","PeriodicalId":37283,"journal":{"name":"Journal of Space Safety Engineering","volume":"11 3","pages":"Pages 446-453"},"PeriodicalIF":1.0,"publicationDate":"2024-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142571560","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Serendipitous detection of orbital debris by the International Liquid Mirror Telescope","authors":"Paul Hickson ,&nbsp;Bhavya Ailawadhi ,&nbsp;Arun S ,&nbsp;Monalisa Dubey ,&nbsp;Naveen Dukiya ,&nbsp;Sara Filali ,&nbsp;Brajesh Kumar ,&nbsp;Kuntal Misra ,&nbsp;Vibhore Negi ,&nbsp;Kumar Pranshu ,&nbsp;Jean Surdej ,&nbsp;Saakshi Turakhia","doi":"10.1016/j.jsse.2024.05.003","DOIUrl":"10.1016/j.jsse.2024.05.003","url":null,"abstract":"<div><div>The International Liquid Mirror Telescope is a 4-m zenith-pointing optical telescope that employs a rotating liquid primary mirror. Located in the Indian Himalayas, it began operations in October 2022. The telescope is equipped with a CCD camera that has a 22 x 22 arcmin field of view and employs time-delay integration readout to compensate for the Earth’s rotation. While its primary purpose is to conduct astronomical survey observations using broad-band filters, the telescope is also sensitive to objects in Earth orbit that pass through its field of view, leaving detectable streaks. We have examined all images obtained during the first year of observations and determined the transit times and position angles of all detected objects. These were compared with publicly available two-line elements, propagated to the time of observation, in order to identify cataloged objects. A total of 301 streaks were found in 1838 images. Of these, 64% were identified with cataloged objects. Most of the identified objects are in low-Earth orbit, in the altitude range of 400–1600 km. The apparent magnitudes of the identified objects range from 3.6 to 15.1 in the V band. It was also possible to infer angular rates, apparent magnitudes and altitudes for 29% of the unidentified objects. The V-band magnitudes range from 6.4 to 19.5 and the estimated altitudes range from 285 to over 300,000 km.</div></div>","PeriodicalId":37283,"journal":{"name":"Journal of Space Safety Engineering","volume":"11 3","pages":"Pages 425-431"},"PeriodicalIF":1.0,"publicationDate":"2024-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142571586","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Infrared photometry and spectrometry of satellites and debris at UKIRT","authors":"Eric C. Pearce ,&nbsp;Harrison Krantz ,&nbsp;Adam Block ,&nbsp;Deatrick L. Foster","doi":"10.1016/j.jsse.2024.07.010","DOIUrl":"10.1016/j.jsse.2024.07.010","url":null,"abstract":"&lt;div&gt;&lt;div&gt;The characterization of deep space debris poses a significant challenge in Space Domain Awareness (SDA). Multi-color photometry and the resultant color indices offer the potential to rapidly discriminate between debris and intact space objects such as rocket bodies and satellites. These multi-color techniques can also identify anomalous members of objects in certain groups and cue higher fidelity data collections and studies. However, multi-color photometry can be difficult to interpret, as the effects of phase and rotation become conflated with the more fundamental material properties of the satellite. Additionally, the broad astronomical photometric bands may not identify key spectral features that can be diagnostic for SDA applications. With our recent observational campaign we have been able to collect 5-color photometry in the near-IR with WFCAM as well as overlapping near-IR spectra with the UKIRT 1–5 μm Imager-Spectrometer (UIST). On a small set of objects, we also have mid-IR spectrophotometry with the Mid-IR esCHELLE (Michelle) imaging spectrograph.&lt;/div&gt;&lt;div&gt;Our previous measurements with the United Kingdom Infrared Telescope (UKIRT) Wide Field Camera (WFCAM) characterized a wide range of space objects with the goal of developing techniques to rapidly discriminate between different classes of objects and to identify anomalous members of these groups. The survey has produced a comprehensive database of 5-color photometry in the Z, Y, J, H, and K bands, analogous to the bands that are anticipated to be exploited by future U.S. ground-based SDA systems. Our current data set includes:&lt;ul&gt;&lt;li&gt;&lt;span&gt;(a)&lt;/span&gt;&lt;span&gt;&lt;div&gt;United States Centaur rocket bodies (RBs),&lt;/div&gt;&lt;/span&gt;&lt;/li&gt;&lt;li&gt;&lt;span&gt;(b)&lt;/span&gt;&lt;span&gt;&lt;div&gt;Molniya communication satellites including the −1 K, 1T, −2, and −3 variants,&lt;/div&gt;&lt;/span&gt;&lt;/li&gt;&lt;li&gt;&lt;span&gt;(c)&lt;/span&gt;&lt;span&gt;&lt;div&gt;Russian FREGAT and SL-6 upper stage RBs in Molniya orbits,&lt;/div&gt;&lt;/span&gt;&lt;/li&gt;&lt;li&gt;&lt;span&gt;(d)&lt;/span&gt;&lt;span&gt;&lt;div&gt;Russian Breeze-M rocket bodies disposed of in GEO-crossing graveyard like orbits, and the Angara-5/Breeze-M mass simulator, also disposed of in a near-GEO orbit,&lt;/div&gt;&lt;/span&gt;&lt;/li&gt;&lt;li&gt;&lt;span&gt;(e)&lt;/span&gt;&lt;span&gt;&lt;div&gt;Intact payloads selected from satellites using the Boeing HS-376 buses—including four different generations of solar panel technology.&lt;/div&gt;&lt;/span&gt;&lt;/li&gt;&lt;/ul&gt;Many of the objects we have studied have significant orbital inclination or drift in the GEO belt. The interpretation of photometry of these objects is especially difficult as phase angle can no longer be considered simply as a single-dimensional quantity. During 2023, we have endeavored to expand our phase angle coverage of a handful of objects and comprehensively sample brightness and color in both components of phase angle. In this paper we present exemplary “phase-phase” diagrams demonstrating this technique and highlight some of the practical and observational difficulties in achieving comprehensive phase angle coverage and interpreti","PeriodicalId":37283,"journal":{"name":"Journal of Space Safety Engineering","volume":"11 3","pages":"Pages 432-438"},"PeriodicalIF":1.0,"publicationDate":"2024-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142571587","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Assessments of the impacts of orbital fragmentations using the Near-Earth Orbital Debris Environment Evolutionary Model (NEODEEM)","authors":"Ryusuke Harada ,&nbsp;Satomi Kawamoto ,&nbsp;Toshiya Hanada","doi":"10.1016/j.jsse.2024.07.008","DOIUrl":"10.1016/j.jsse.2024.07.008","url":null,"abstract":"<div><div>This study evaluates the environmental impacts of orbital fragmentation such as an anti-satellite test, collision between two objects, and explosion. A debris environment evolutionary model named NEODEEM, jointly developed by Kyushu University and JAXA, is used to predict future populations and calculate collision probabilities after a fragmentation. This study focuses on characteristics of the fragmented objects, such as altitude, mass, and whether they belong to a Large Constellation (LC). When a fragmentation occurs at higher altitudes, the new fragments will remain in orbit for a long time. Due to this accumulation, the fragments will not only keep the number of objects and probability of collision higher but also cause the risk of secondary collisions between fragments and background objects. When a collision occurs inside an LC at a lower altitude, the impacts will be short-term because most of fragments decay quickly. However, the number of conjunctions, i.e., operational roads, will increase rapidly because many satellites are operated at the same altitude. This study also discusses a collision probability to an LC taking into account the small size of fragments larger than 1 cm.</div></div>","PeriodicalId":37283,"journal":{"name":"Journal of Space Safety Engineering","volume":"11 3","pages":"Pages 395-402"},"PeriodicalIF":1.0,"publicationDate":"2024-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142571638","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"AstroLibrary: A library for real-time conjunction assessment and optimal collision avoidance","authors":"Shawn SH Choi ,&nbsp;Peter JH Ryu ,&nbsp;Kyuil Sim ,&nbsp;Jaedong Seong ,&nbsp;Jae Wook Song ,&nbsp;Misoon Mah ,&nbsp;Douglas DS Kim","doi":"10.1016/j.jsse.2024.07.003","DOIUrl":"10.1016/j.jsse.2024.07.003","url":null,"abstract":"<div><div>Geospace is crowded due to the proliferation of satellites and space debris and will become more crowded with the increasing deployment of new space missions. This trend is rapidly increasing the probability of collisions between space objects. Space objects fly at extreme speeds; hence, the consequences of collisions are catastrophic. However, accurate and efficient conjunction assessment (CA) and collision avoidance (COLA) have long been challenging, even with the current space catalogues of O(10⁴) size. As the space catalogue size increases owing to the increased number of new satellites, improved sensor capabilities, and Kessler syndrome, the situation will worsen unless a paradigm-transforming computational method is devised. Here, we present the SpaceMap method, which can perform real-time CA and near-real-time COLA for O(10⁶) or more objects, provided that the spatiotemporal proximity amongst satellites is represented in a Voronoi diagram. As the most concise and efficient data structure for spatiotemporal reasoning amongst moving objects, Voronoi diagrams play a key role in the mathematical and computational basis for a new genre of artificial intelligence (AI) called space–time AI, which can find the best solutions to CA/COLA and other space decision-making problems in longer timeline windows. The algorithms are implemented in C++ and are available on GitHub as AstroLibrary, which has RESTful APIs and Python packages that can be called from application programs. Using this library, anyone with elementary programming skills can easily develop efficient applications for challenging spatiotemporal problems.</div></div>","PeriodicalId":37283,"journal":{"name":"Journal of Space Safety Engineering","volume":"11 3","pages":"Pages 462-468"},"PeriodicalIF":1.0,"publicationDate":"2024-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141712222","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"An economic indicator of the orbital debris environment","authors":"","doi":"10.1016/j.jsse.2024.04.014","DOIUrl":"10.1016/j.jsse.2024.04.014","url":null,"abstract":"<div><div>The continued growth of orbital debris increases potential losses faced by commercial operators in Earth's orbits. Yet, there is no commonly accepted measure that describes the orbital debris environment from an <em>economic</em> perspective. This study begins to fill that gap by developing an Orbital Debris Economic Loss Index (ODELI) that measures and tracks the changes in the expected negative economic impact of orbital debris on satellite operators, both in aggregate and in specific orbits. Such information is valuable to the stakeholders, such as policymakers, commercial operators, and the public, in communicating valuable information about the economic state of the orbital debris environment.</div><div>We illustrate the calculation of the index utilizing the data from 2012 to 2022. The analysis is based on the publicly available data and the Meteoroid and Space Debris Terrestrial Environment Reference (MASTER) orbital debris environment model. Our analysis suggests that the aggregate expected economic damage to Earth's orbits is increasing at a slower rate than the growth rate of the number of satellites or trackable pieces of debris objects. The slower rate of growth in ODELI indices from 2012 to 2022 is explained by a decrease in the average mass of satellites, a reduction in the real cost of placing satellites in orbit, and a commercial preference to launch satellites into orbits with lower debris density.</div><div>The estimates of annual expected economic losses from debris collisions increased from $86 million to $107 million from 2012 to 2022, and the losses are concentrated in the low-Earth orbit (LEO). However, LEO had the smallest rate of increase in ODELI compared to other orbits. Medium-Earth orbit (MEO), which has the smallest contribution to the combined expected economic losses from debris on the Earth's orbits, experienced the fastest rate of increase in ODELI during the same period.</div></div>","PeriodicalId":37283,"journal":{"name":"Journal of Space Safety Engineering","volume":"11 3","pages":"Pages 539-545"},"PeriodicalIF":1.0,"publicationDate":"2024-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141053161","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Evaluation of low earth orbit post-mission disposal measures","authors":"Hugh G. Lewis,&nbsp;Vyara Yazadzhiyan","doi":"10.1016/j.jsse.2024.03.008","DOIUrl":"10.1016/j.jsse.2024.03.008","url":null,"abstract":"<div><div>The substantial benefits arising from the widespread adoption of post-mission disposal in low Earth orbit (LEO) are reflected in a reduced orbital debris population and a reduced frequency of collisions. The benefits are generally seen at higher altitudes whereas some drawbacks in the form of enhanced collision risks have been predicted for lower altitudes. These drawbacks are generally expected to reduce as the post-mission disposal lifetime decreases, as less time at lower altitudes reduces collision probability. This is the rationale used by the Federal Communications Commission (FCC) for its new 5-year rule. To investigate the potential benefits and drawbacks, the DAMAGE computational model was used to investigate the effects of a variety of LEO post-mission disposal rules, including the new 5-year rule, within scenarios involving the deployment of large constellations of satellites. The results suggest substantial reductions in conjunction rates overall, as the post-mission residual orbital lifetime decreases, but indicate an increasing frequency of conjunctions and a corresponding need for risk mitigation maneuvers at low altitudes. The results reinforce the recommendation that disposal must be completed as soon as practicable following end of mission. Additionally, the results highlight the need for careful consideration and further research into post-mission disposal where a residual orbital lifetime is permitted.</div></div>","PeriodicalId":37283,"journal":{"name":"Journal of Space Safety Engineering","volume":"11 3","pages":"Pages 526-531"},"PeriodicalIF":1.0,"publicationDate":"2024-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142571487","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}