Pub Date : 2009-03-07DOI: 10.1109/AERO.2009.4839537
Y. Ishijima, N. Inaba, A. Matsumoto, K. Terada, Hiroo Yonechi, Hitoshi Ebisutani, Shinichi Ukawa, Takeshi Okamoto
The Quasi-zenith Satellite (QZS-1) is the first Japanese first navigation satellite to demonstrate the technology for providing GPS interoperable and augmentation services around Japan and Oceania. The attitude and orbit control system (AOCS) of the QZS-1 has several features that improve the mission availability. The use of a star tracker in a GEO altitude orbit and yaw steering function for high inclination are important features. In addition, robust software can maintain nominal operation, even in cases where one failure would occur in attitude sensors, actuators, or the main computer. Furthermore, the intervals of reaction wheel momentum unloading and orbital maneuvers are maximized by optimizing the system design and considering disturbances, such as solar radiation pressure, orbital perturbations, and thrust variations. As described herein, we present an overview and the design results of the QZS-1 attitude and orbit control system.
{"title":"Design and development of the first Quasi-Zenith Satellite attitude and orbit control system","authors":"Y. Ishijima, N. Inaba, A. Matsumoto, K. Terada, Hiroo Yonechi, Hitoshi Ebisutani, Shinichi Ukawa, Takeshi Okamoto","doi":"10.1109/AERO.2009.4839537","DOIUrl":"https://doi.org/10.1109/AERO.2009.4839537","url":null,"abstract":"The Quasi-zenith Satellite (QZS-1) is the first Japanese first navigation satellite to demonstrate the technology for providing GPS interoperable and augmentation services around Japan and Oceania. The attitude and orbit control system (AOCS) of the QZS-1 has several features that improve the mission availability. The use of a star tracker in a GEO altitude orbit and yaw steering function for high inclination are important features. In addition, robust software can maintain nominal operation, even in cases where one failure would occur in attitude sensors, actuators, or the main computer. Furthermore, the intervals of reaction wheel momentum unloading and orbital maneuvers are maximized by optimizing the system design and considering disturbances, such as solar radiation pressure, orbital perturbations, and thrust variations. As described herein, we present an overview and the design results of the QZS-1 attitude and orbit control system.","PeriodicalId":117250,"journal":{"name":"2009 IEEE Aerospace conference","volume":"21 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2009-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131710306","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}
Pub Date : 2009-03-07DOI: 10.1109/AERO.2009.4839465
I. Hahn, M. Weilert, J. Sandhu, F. Dekens, R. Goullioud
The Space Interferometry Mission Planet Quest Lite (SIM-Lite) is a new mission concept to perform micro-arcsecond narrow-angle astrometry to search approximately 50 nearby stars for Earth-like planets, and also to perform a global astrometry. The SIM-Lite consists of two Michelson interferometers and one telescope. The main six-meter baseline science interferometer observes a target star and a set of reference stars. The four-meter baseline interferometer (Guide-1) monitors the attitude of the instrument in the direction of a target star. A new Guide-2 telescope (G2T) tracks a bright star to monitor the attitude of the instrument in the other two orthogonal directions. In the current mission concept, the G2T consists of a 30 cm siderostat and a 30 cm confocal telescope, similar to other four telescopes used in the science and Guide-1 interferometers. A testbed has been built to demonstrate the G2T feasibility for SIM-Lite mission. Recent results show that field-independent, star-tracking capability of the system is less than 30 mas after the SIM narrow angle analysis.
{"title":"Recent results of the Guide-2 telescope testbed for the SIM-Lite mission","authors":"I. Hahn, M. Weilert, J. Sandhu, F. Dekens, R. Goullioud","doi":"10.1109/AERO.2009.4839465","DOIUrl":"https://doi.org/10.1109/AERO.2009.4839465","url":null,"abstract":"The Space Interferometry Mission Planet Quest Lite (SIM-Lite) is a new mission concept to perform micro-arcsecond narrow-angle astrometry to search approximately 50 nearby stars for Earth-like planets, and also to perform a global astrometry. The SIM-Lite consists of two Michelson interferometers and one telescope. The main six-meter baseline science interferometer observes a target star and a set of reference stars. The four-meter baseline interferometer (Guide-1) monitors the attitude of the instrument in the direction of a target star. A new Guide-2 telescope (G2T) tracks a bright star to monitor the attitude of the instrument in the other two orthogonal directions. In the current mission concept, the G2T consists of a 30 cm siderostat and a 30 cm confocal telescope, similar to other four telescopes used in the science and Guide-1 interferometers. A testbed has been built to demonstrate the G2T feasibility for SIM-Lite mission. Recent results show that field-independent, star-tracking capability of the system is less than 30 mas after the SIM narrow angle analysis.","PeriodicalId":117250,"journal":{"name":"2009 IEEE Aerospace conference","volume":"28 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2009-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123170275","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}
Pub Date : 2009-03-07DOI: 10.1109/AERO.2009.4839580
U. Rebbapragada, L. Mandrake, K. Wagstaff, D. Gleeson, R. Castaño, Steve Ankuo Chien, C. Brodley
This paper presents PWEM, a technique for detecting class label noise in training data. PWEM detects mislabeled examples by assigning to each training example a probability that its label is correct. PWEM calculates this probability by clustering examples from pairs of classes together and analyzing the distribution of labels within each cluster to derive the probability of each label's correctness. We discuss how one can use the probabilities output by PWEM to filter, mitigate, or correct mislabeled training examples. We then provide an in-depth discussion of how we applied PWEM to a sulfur detector that labels pixels from Hyperion images of the Borup-Fiord pass in Northern Canada. PWEM assigned a large number of the sulfur training examples low probabilities, indicating severe mislabeling within the sulfur class. The filtering of those low confidence examples resulted in a cleaner training set and improved the median false positive rate of the classifier by at least 29%.
{"title":"Improving onboard analysis of Hyperion images by filtering mislabeled training data examples","authors":"U. Rebbapragada, L. Mandrake, K. Wagstaff, D. Gleeson, R. Castaño, Steve Ankuo Chien, C. Brodley","doi":"10.1109/AERO.2009.4839580","DOIUrl":"https://doi.org/10.1109/AERO.2009.4839580","url":null,"abstract":"This paper presents PWEM, a technique for detecting class label noise in training data. PWEM detects mislabeled examples by assigning to each training example a probability that its label is correct. PWEM calculates this probability by clustering examples from pairs of classes together and analyzing the distribution of labels within each cluster to derive the probability of each label's correctness. We discuss how one can use the probabilities output by PWEM to filter, mitigate, or correct mislabeled training examples. We then provide an in-depth discussion of how we applied PWEM to a sulfur detector that labels pixels from Hyperion images of the Borup-Fiord pass in Northern Canada. PWEM assigned a large number of the sulfur training examples low probabilities, indicating severe mislabeling within the sulfur class. The filtering of those low confidence examples resulted in a cleaner training set and improved the median false positive rate of the classifier by at least 29%.","PeriodicalId":117250,"journal":{"name":"2009 IEEE Aerospace conference","volume":"52 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2009-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126450625","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}
Pub Date : 2009-03-07DOI: 10.1109/AERO.2009.4839475
Amadou Ba, N. Mechbal, M. Vergé, S. Hbaieb
Real-time monitoring of a drilling process is an essential task in improving their performances. Faults that might occur have to be detected as soon as possible in order to preserve drilling efficiency. In this paper, drilling process monitoring by identifying time varying parameters through Marginalized Particle Filter (MPF) is treated. The idea consists in enhancing the tracking ability of parameters change by integrating into the process model a part that represents the faulty process and another when the process is safe. The efficiency of the developed approach is highlighted through simulated and experimental data obtained from tests campaign.
{"title":"On-line drilling process monitoring by Marginalized Particle Filter","authors":"Amadou Ba, N. Mechbal, M. Vergé, S. Hbaieb","doi":"10.1109/AERO.2009.4839475","DOIUrl":"https://doi.org/10.1109/AERO.2009.4839475","url":null,"abstract":"Real-time monitoring of a drilling process is an essential task in improving their performances. Faults that might occur have to be detected as soon as possible in order to preserve drilling efficiency. In this paper, drilling process monitoring by identifying time varying parameters through Marginalized Particle Filter (MPF) is treated. The idea consists in enhancing the tracking ability of parameters change by integrating into the process model a part that represents the faulty process and another when the process is safe. The efficiency of the developed approach is highlighted through simulated and experimental data obtained from tests campaign.","PeriodicalId":117250,"journal":{"name":"2009 IEEE Aerospace conference","volume":"3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2009-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116110276","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}
Pub Date : 2009-03-07DOI: 10.1109/AERO.2009.4839505
J. Marshall, Neil Wood, M. Milliser, R. Ferguson, Ed Maher
Over the past decade, the amount of processing utilized in spacecraft has increased. From below 1 MIP in the 1980s to single digit MIPS in the early 1990s to 10s of MIPS by the end of the twentieth century to hundreds of MIPS today, the amount of processing is in an upward trend paralleling though lagging the commercial and military embedded processing markets. This has allowed processing to move from simple control and data handling (C&DH) into payloads and other data processing intensive areas. Along with this memory capacities have increased to provide storage for programs and data.
{"title":"Higher performance BAE systems processors and interconnects enabling spacecraft applications","authors":"J. Marshall, Neil Wood, M. Milliser, R. Ferguson, Ed Maher","doi":"10.1109/AERO.2009.4839505","DOIUrl":"https://doi.org/10.1109/AERO.2009.4839505","url":null,"abstract":"Over the past decade, the amount of processing utilized in spacecraft has increased. From below 1 MIP in the 1980s to single digit MIPS in the early 1990s to 10s of MIPS by the end of the twentieth century to hundreds of MIPS today, the amount of processing is in an upward trend paralleling though lagging the commercial and military embedded processing markets. This has allowed processing to move from simple control and data handling (C&DH) into payloads and other data processing intensive areas. Along with this memory capacities have increased to provide storage for programs and data.","PeriodicalId":117250,"journal":{"name":"2009 IEEE Aerospace conference","volume":"160 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2009-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116159824","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}
Pub Date : 2009-03-07DOI: 10.1109/AERO.2009.4839481
Todd Fercho, D. Papageorgiou
System-level discrimination performance for missile defense relies on how well data can be associated between participating sensors. Under the existing architecture, there may be a handover of tracks between two sensors in which tracks formed by one sensor are passed to another sensor to improve knowledge of the targets. The global nearest pattern matching (GNPM) problem is a mathematical programming formulation that has proven to be successful at correctly correlating tracks based solely on kinematic data from two sensors, while simultaneously removing inter-sensor bias and accounting for false tracks and missed detections. Despite this success, there is continued interest to improve correlation performance by exploiting feature data collected on targets. This paper addresses this issue by extending the GNPM formulation to account for feature observations whose measurement errors follow an arbitrary distribution. This is accomplished by augmenting the GNPM likelihood function to include a term representing the incremental likelihood of track-to-track assignments based solely on feature observations. Computational results are presented to illustrate the success of this approach.
{"title":"Feature-aided global nearest pattern matching with non-Gaussian feature measurement errors","authors":"Todd Fercho, D. Papageorgiou","doi":"10.1109/AERO.2009.4839481","DOIUrl":"https://doi.org/10.1109/AERO.2009.4839481","url":null,"abstract":"System-level discrimination performance for missile defense relies on how well data can be associated between participating sensors. Under the existing architecture, there may be a handover of tracks between two sensors in which tracks formed by one sensor are passed to another sensor to improve knowledge of the targets. The global nearest pattern matching (GNPM) problem is a mathematical programming formulation that has proven to be successful at correctly correlating tracks based solely on kinematic data from two sensors, while simultaneously removing inter-sensor bias and accounting for false tracks and missed detections. Despite this success, there is continued interest to improve correlation performance by exploiting feature data collected on targets. This paper addresses this issue by extending the GNPM formulation to account for feature observations whose measurement errors follow an arbitrary distribution. This is accomplished by augmenting the GNPM likelihood function to include a term representing the incremental likelihood of track-to-track assignments based solely on feature observations. Computational results are presented to illustrate the success of this approach.","PeriodicalId":117250,"journal":{"name":"2009 IEEE Aerospace conference","volume":"7 9","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2009-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121007159","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}
Pub Date : 2009-03-07DOI: 10.1109/AERO.2009.4839455
Anthony P. O'Dell, S. Cain
Computer simulations are used to compare the results of correlating a simulated image of an asteroid with a point spread function while varying the atmospheric parameter. The images contain a point source object that is smeared due to the atmosphere. The point spread function is calculated using r0, since r0 can be measured at the time of time of data collection. These results are evaluated against an uncorrelated threshold detection algorithm using the same data input. The resulting receiver operating characteristic (ROC) curves show the effects of the different atmospheres on detection of different sized Near Earth Objects (NEOs) for both the correlation and threshold algorithm. These results are discussed and compared. Recommendations are made for applying these algorithms in the search for NEOs.
{"title":"Investigating the effects of atmospheric seeing on the detection of near earth orbiting asteroids","authors":"Anthony P. O'Dell, S. Cain","doi":"10.1109/AERO.2009.4839455","DOIUrl":"https://doi.org/10.1109/AERO.2009.4839455","url":null,"abstract":"Computer simulations are used to compare the results of correlating a simulated image of an asteroid with a point spread function while varying the atmospheric parameter. The images contain a point source object that is smeared due to the atmosphere. The point spread function is calculated using r0, since r0 can be measured at the time of time of data collection. These results are evaluated against an uncorrelated threshold detection algorithm using the same data input. The resulting receiver operating characteristic (ROC) curves show the effects of the different atmospheres on detection of different sized Near Earth Objects (NEOs) for both the correlation and threshold algorithm. These results are discussed and compared. Recommendations are made for applying these algorithms in the search for NEOs.","PeriodicalId":117250,"journal":{"name":"2009 IEEE Aerospace conference","volume":"185 2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2009-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124920674","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}
Pub Date : 2009-03-07DOI: 10.1109/AERO.2009.4839621
David H. Bushnell, D. Giannakopoulou, P. Mehlitz, R. Paielli, C. Pasareanu
The expected future increase in air traffic requires the development of innovative algorithms and software systems to automate safety critical functions such as separation assurance - the task of maintaining a safe distance between aircraft at all times. Extensive verification and validation (V&V) of such functions will be crucial for the acceptance of new air traffic management systems. This paper reports on work performed at the NASA Ames Research Center. We discuss how advanced V&V technologies can be used to create robust software prototypes for air traffic control software, and how conformance of production code with such prototypes can be assured. We present preliminary results of V&V efforts for a prototype of the Tactical Separation Assisted Flight Environment system (TSAFE).
{"title":"Verification and validation of air traffic systems: Tactical separation assurance","authors":"David H. Bushnell, D. Giannakopoulou, P. Mehlitz, R. Paielli, C. Pasareanu","doi":"10.1109/AERO.2009.4839621","DOIUrl":"https://doi.org/10.1109/AERO.2009.4839621","url":null,"abstract":"The expected future increase in air traffic requires the development of innovative algorithms and software systems to automate safety critical functions such as separation assurance - the task of maintaining a safe distance between aircraft at all times. Extensive verification and validation (V&V) of such functions will be crucial for the acceptance of new air traffic management systems. This paper reports on work performed at the NASA Ames Research Center. We discuss how advanced V&V technologies can be used to create robust software prototypes for air traffic control software, and how conformance of production code with such prototypes can be assured. We present preliminary results of V&V efforts for a prototype of the Tactical Separation Assisted Flight Environment system (TSAFE).","PeriodicalId":117250,"journal":{"name":"2009 IEEE Aerospace conference","volume":"200 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2009-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123021394","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}
Pub Date : 2009-03-07DOI: 10.1109/AERO.2009.4839661
E. Balaban, P. Bansal, P. Stoelting, A. Saxena, K. Goebel, S. Curran
Electro-mechanical actuators (EMA) are finding increasing use in aerospace applications, especially with the trend towards all all-electric aircraft and spacecraft designs. However, electro-mechanical actuators still lack the knowledge base accumulated for other fielded actuator types, particularly with regard to fault detection and characterization. This paper presents a thorough analysis of some of the critical failure modes documented for EMAs and describes experiments conducted on detecting and isolating a subset of them. The list of failures has been prepared through an extensive Failure Modes and Criticality Analysis (FMECA) reference, literature review, and accessible industry experience. Methods for data acquisition and validation of algorithms on EMA test stands are described. A variety of condition indicators were developed that enabled detection, identification, and isolation among the various fault modes. A diagnostic algorithm based on an artificial neural network is shown to operate successfully using these condition indicators and furthermore, robustness of these diagnostic routines to sensor faults is demonstrated by showing their ability to distinguish between them and component failures. The paper concludes with a roadmap leading from this effort towards developing successful prognostic algorithms for electromechanical actuators.
{"title":"A diagnostic approach for electro-mechanical actuators in aerospace systems","authors":"E. Balaban, P. Bansal, P. Stoelting, A. Saxena, K. Goebel, S. Curran","doi":"10.1109/AERO.2009.4839661","DOIUrl":"https://doi.org/10.1109/AERO.2009.4839661","url":null,"abstract":"Electro-mechanical actuators (EMA) are finding increasing use in aerospace applications, especially with the trend towards all all-electric aircraft and spacecraft designs. However, electro-mechanical actuators still lack the knowledge base accumulated for other fielded actuator types, particularly with regard to fault detection and characterization. This paper presents a thorough analysis of some of the critical failure modes documented for EMAs and describes experiments conducted on detecting and isolating a subset of them. The list of failures has been prepared through an extensive Failure Modes and Criticality Analysis (FMECA) reference, literature review, and accessible industry experience. Methods for data acquisition and validation of algorithms on EMA test stands are described. A variety of condition indicators were developed that enabled detection, identification, and isolation among the various fault modes. A diagnostic algorithm based on an artificial neural network is shown to operate successfully using these condition indicators and furthermore, robustness of these diagnostic routines to sensor faults is demonstrated by showing their ability to distinguish between them and component failures. The paper concludes with a roadmap leading from this effort towards developing successful prognostic algorithms for electromechanical actuators.","PeriodicalId":117250,"journal":{"name":"2009 IEEE Aerospace conference","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2009-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131504083","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}
Pub Date : 2009-03-07DOI: 10.1109/AERO.2009.4839417
Yoshinori Kondoh, Y. Ishijima, I. Kawano, T. Iwata, Hideto Suzuki, Susumu Kumagai, Masahiro Kakinuma, Tomoaki Eda, Masaru Kasahara
We are investigating a New Generation Spaceborne GPS Receiver that can determine a position more precisely, but which is smaller, with lower cost and lower power consumption than a conventional receiver. This new type of spaceborne receiver includes a CMOS Silicon on Insulator (SOI) chip and adopts a direct
{"title":"Development of a New Generation Spaceborne GPS Receiver","authors":"Yoshinori Kondoh, Y. Ishijima, I. Kawano, T. Iwata, Hideto Suzuki, Susumu Kumagai, Masahiro Kakinuma, Tomoaki Eda, Masaru Kasahara","doi":"10.1109/AERO.2009.4839417","DOIUrl":"https://doi.org/10.1109/AERO.2009.4839417","url":null,"abstract":"We are investigating a New Generation Spaceborne GPS Receiver that can determine a position more precisely, but which is smaller, with lower cost and lower power consumption than a conventional receiver. This new type of spaceborne receiver includes a CMOS Silicon on Insulator (SOI) chip and adopts a direct","PeriodicalId":117250,"journal":{"name":"2009 IEEE Aerospace conference","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2009-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126979333","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}
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