Pub Date : 2009-03-07DOI: 10.1109/AERO.2009.4839674
B. Ling, M. Khonsari, A. Mesgarnejad, Ross Hathaway
We present a feasibility analysis for the development of an online ball bearing fault detection and identification method which can effectively classify various fault stages related to the contact in the coated ball bearings using vibration measurements. To detect ball bearing faulty stages, we have developed new degree of randomness (DoR) analysis methods using Shannon entropy and random covariance matrix norm theory. To classify the fault stages, we have further developed a set of stochastic models using Gaussian Mixture Hidden Markov Model (GM-HMM) theory. Test results have shown that our algorithms can predict bearing failures without using actual failure data.
{"title":"Online coated ball bearing health monitoring using degree of randomness and Hidden Markov Model","authors":"B. Ling, M. Khonsari, A. Mesgarnejad, Ross Hathaway","doi":"10.1109/AERO.2009.4839674","DOIUrl":"https://doi.org/10.1109/AERO.2009.4839674","url":null,"abstract":"We present a feasibility analysis for the development of an online ball bearing fault detection and identification method which can effectively classify various fault stages related to the contact in the coated ball bearings using vibration measurements. To detect ball bearing faulty stages, we have developed new degree of randomness (DoR) analysis methods using Shannon entropy and random covariance matrix norm theory. To classify the fault stages, we have further developed a set of stochastic models using Gaussian Mixture Hidden Markov Model (GM-HMM) theory. Test results have shown that our algorithms can predict bearing failures without using actual failure data.","PeriodicalId":117250,"journal":{"name":"2009 IEEE Aerospace conference","volume":"39 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":"123212770","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.2009.4839618
J. Schumann, K. Gundy-Burlet, T. Menzies, A. Barrett
Modern aerospace software systems simulations usually contain many (dependent and independent) parameters. Due to the large parameter space, and the complex, highly coupled nonlinear nature of the different system components, analysis is complicated and time consuming. Thus, such systems are generally validated only in regions local to anticipated operating points rather than through characterization of the entire feasible operational envelope of the system. We have addressed the factors deterring such a comprehensive analysis with a tool to support parametric analysis and envelope assessment: a combination of advanced Monte Carlo generation with n-factor combinatorial parameter variations and model-based testcase generation is used to limit the number of cases without sacrificing important interactions in the parameter space. For the automatic analysis of the generated data we use unsupervised Bayesian clustering techniques (AutoBayes) and supervised learning of critical parameter ranges using the treatment learner TAR3. This unique combination of advanced machine learning technology enables a fast and powerful multivariate analysis that supports finding of root causes.
{"title":"Software V&V support by parametric analysis of large software simulation systems","authors":"J. Schumann, K. Gundy-Burlet, T. Menzies, A. Barrett","doi":"10.1109/AERO.2009.4839618","DOIUrl":"https://doi.org/10.1109/AERO.2009.4839618","url":null,"abstract":"Modern aerospace software systems simulations usually contain many (dependent and independent) parameters. Due to the large parameter space, and the complex, highly coupled nonlinear nature of the different system components, analysis is complicated and time consuming. Thus, such systems are generally validated only in regions local to anticipated operating points rather than through characterization of the entire feasible operational envelope of the system. We have addressed the factors deterring such a comprehensive analysis with a tool to support parametric analysis and envelope assessment: a combination of advanced Monte Carlo generation with n-factor combinatorial parameter variations and model-based testcase generation is used to limit the number of cases without sacrificing important interactions in the parameter space. For the automatic analysis of the generated data we use unsupervised Bayesian clustering techniques (AutoBayes) and supervised learning of critical parameter ranges using the treatment learner TAR3. This unique combination of advanced machine learning technology enables a fast and powerful multivariate analysis that supports finding of root causes.","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":"123428999","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.2009.4839669
Sachin Kumar, E. Dolev, M. Pecht, M. Pompetzki
This paper presents a new residual estimation based diagnostic approach that includes detection and fault isolation using the Mahalanobis distance (MD). The faulty performance parameter isolation approach is based on the analysis of residual MD values. The residual value is calculated by taking the difference between MD values estimated in two different scenarios: first, when a performance parameter is present, and second, when that performance parameter is absent. The residual of the MD values for each parameter is obtained by using training data from several experiments as part of the training data analysis planned by the design-of-experiment concept to analyze the impact of each parameter. The distribution of residual MD values for each parameter is analyzed and a 95% probabilistic range is established. This range represents the expected contribution by parameters toward a healthy system's MDs, and it is used to identify the parameters that are responsible for the anomalous behavior of a system. Parameters that fall below the lower bound of the 95% probabilistic range are considered candidates for the anomalous behavior, and the parameter that has the lowest residual value is isolated as the faulty parameter. A case study on computers is presented to demonstrate and test the suggested new approach's ability to isolate faulty parameters.
{"title":"A residual estimation based approach for isolating faulty parameters","authors":"Sachin Kumar, E. Dolev, M. Pecht, M. Pompetzki","doi":"10.1109/AERO.2009.4839669","DOIUrl":"https://doi.org/10.1109/AERO.2009.4839669","url":null,"abstract":"This paper presents a new residual estimation based diagnostic approach that includes detection and fault isolation using the Mahalanobis distance (MD). The faulty performance parameter isolation approach is based on the analysis of residual MD values. The residual value is calculated by taking the difference between MD values estimated in two different scenarios: first, when a performance parameter is present, and second, when that performance parameter is absent. The residual of the MD values for each parameter is obtained by using training data from several experiments as part of the training data analysis planned by the design-of-experiment concept to analyze the impact of each parameter. The distribution of residual MD values for each parameter is analyzed and a 95% probabilistic range is established. This range represents the expected contribution by parameters toward a healthy system's MDs, and it is used to identify the parameters that are responsible for the anomalous behavior of a system. Parameters that fall below the lower bound of the 95% probabilistic range are considered candidates for the anomalous behavior, and the parameter that has the lowest residual value is isolated as the faulty parameter. A case study on computers is presented to demonstrate and test the suggested new approach's ability to isolate faulty parameters.","PeriodicalId":117250,"journal":{"name":"2009 IEEE Aerospace conference","volume":"15 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":"123938910","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.2009.4839422
F. Palmieri, G. Romano, E. Venosa
In this paper we propose a methodology for designing a fully-digital reconfigurable receiver for QAM signals. Band-Pass Sampling (BPS) is used as a first stage with a unique Analog-to-Digital Converter (ADC) positioned immediately after the receiver antenna. The band-pass sampling is analyzed with reference to noise aliasing deriving from band-pass filter and the results in the numerical frequency domain are presented. The inescapable frequency, symbol and phase synchronization problem in our model of receiver is approached and solved blindly with an information-theoretic criterion: joint entropy maximization is utilized for frequency and symbol synchronization while mutual information minimization is utilized for phase recovery. The innovative contribution of this paper consists in matching band-pass sampling and blind synchronization with a design of a synchronized reconfigurable receiver for QAM signals.
{"title":"QAM Receiver with Band-Pass Sampling and blind synchronization","authors":"F. Palmieri, G. Romano, E. Venosa","doi":"10.1109/AERO.2009.4839422","DOIUrl":"https://doi.org/10.1109/AERO.2009.4839422","url":null,"abstract":"In this paper we propose a methodology for designing a fully-digital reconfigurable receiver for QAM signals. Band-Pass Sampling (BPS) is used as a first stage with a unique Analog-to-Digital Converter (ADC) positioned immediately after the receiver antenna. The band-pass sampling is analyzed with reference to noise aliasing deriving from band-pass filter and the results in the numerical frequency domain are presented. The inescapable frequency, symbol and phase synchronization problem in our model of receiver is approached and solved blindly with an information-theoretic criterion: joint entropy maximization is utilized for frequency and symbol synchronization while mutual information minimization is utilized for phase recovery. The innovative contribution of this paper consists in matching band-pass sampling and blind synchronization with a design of a synchronized reconfigurable receiver for QAM signals.","PeriodicalId":117250,"journal":{"name":"2009 IEEE Aerospace conference","volume":"37 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":"128372654","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.2009.4839403
R. Orr
In a CDMA system where multiple users share bandwidth in common, multiple access interference (MAI) acts as noise that adds to the receiver thermal noise. To overcome MAI, margin must be added to each user's transmit power. The amount of margin required to achieve this for the homogeneous case in which all users have the same parameters has been known for some time. The general solution for required transmit margin when the user parameters are arbitrary—the inhomogeneous case—is developed in this paper. The solution exhibits an “inverse Robin Hood” characteristic in which less demanding users “subsidize” the more demanding ones by providing a greater share of MAI margin. This behavior is an inherent attribute of CDMA that cannot be overcome except by the elimination of MAI through strictly orthogonal signals.
{"title":"CDMA is unfair: Transmit margin in an inhomogeneous user community","authors":"R. Orr","doi":"10.1109/AERO.2009.4839403","DOIUrl":"https://doi.org/10.1109/AERO.2009.4839403","url":null,"abstract":"In a CDMA system where multiple users share bandwidth in common, multiple access interference (MAI) acts as noise that adds to the receiver thermal noise. To overcome MAI, margin must be added to each user's transmit power. The amount of margin required to achieve this for the homogeneous case in which all users have the same parameters has been known for some time. The general solution for required transmit margin when the user parameters are arbitrary—the inhomogeneous case—is developed in this paper. The solution exhibits an “inverse Robin Hood” characteristic in which less demanding users “subsidize” the more demanding ones by providing a greater share of MAI margin. This behavior is an inherent attribute of CDMA that cannot be overcome except by the elimination of MAI through strictly orthogonal signals.","PeriodicalId":117250,"journal":{"name":"2009 IEEE Aerospace conference","volume":"5 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":"129595388","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.2009.4839529
D. Schatzel
There is a trend continuing in the electronics industry where high reliability electronic packages are using standard epoxy glass and polyimide substrates over ceramic based substrates. This is a result of improved fabrication accuracy and consistent raw material properties. Increased processing power is resulting in increased heat generation. Printed circuit boards are becoming very dense as a result of improved fabrication processes that allow smaller vias, smaller trace line width/spaces and pad size. This is combined with designs that have multiple internal conductive layers that routinely reach 20 to 25 layers. This increased processing power is affecting printed circuit board designs for space electronic applications. The additional heat must be conducted from a microprocessor or power device through the printed circuit board to the board frame or chassis. This has been achievable for processing devices by utilizing thick copper layers and thermal vias to transfer the resultant heat. The result of increasing the copper thickness is an increase in mass which is an undesirable condition where the goal for electronics is a smaller and lighter electronic package.
{"title":"Improving heat transfer performance of printed circuit boards","authors":"D. Schatzel","doi":"10.1109/AERO.2009.4839529","DOIUrl":"https://doi.org/10.1109/AERO.2009.4839529","url":null,"abstract":"There is a trend continuing in the electronics industry where high reliability electronic packages are using standard epoxy glass and polyimide substrates over ceramic based substrates. This is a result of improved fabrication accuracy and consistent raw material properties. Increased processing power is resulting in increased heat generation. Printed circuit boards are becoming very dense as a result of improved fabrication processes that allow smaller vias, smaller trace line width/spaces and pad size. This is combined with designs that have multiple internal conductive layers that routinely reach 20 to 25 layers. This increased processing power is affecting printed circuit board designs for space electronic applications. The additional heat must be conducted from a microprocessor or power device through the printed circuit board to the board frame or chassis. This has been achievable for processing devices by utilizing thick copper layers and thermal vias to transfer the resultant heat. The result of increasing the copper thickness is an increase in mass which is an undesirable condition where the goal for electronics is a smaller and lighter electronic package.","PeriodicalId":117250,"journal":{"name":"2009 IEEE Aerospace conference","volume":"20 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":"127342865","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.2009.4839518
W. Bjorndahl
It is often the case in failure and anomaly investigations that data is either limited or so wide ranging that it is difficult to bring focus to a key root cause. For this reason, a disciplined approach incorporating root cause trees (Ishikawa Diagrams) is usually taken to develop and track root cause hypotheses and analyses. During the investigation, statistical tools can be used to evaluate various hypotheses of failure. However, in many cases, there is limited failure data and it is often necessary to set up accelerated life tests involving many samples in order to induce failures under controlled conditions so that a statistically significant population of failures can be obtained. Root cause is sometimes achieved only after extensive and expensive efforts to reduce the number of root cause hypotheses. Other times, root cause investigations are truncated to “most probable cause” based on the evidence available and expert opinion.
{"title":"Benefits of a Bayesian approach to anomaly and failure investigations","authors":"W. Bjorndahl","doi":"10.1109/AERO.2009.4839518","DOIUrl":"https://doi.org/10.1109/AERO.2009.4839518","url":null,"abstract":"It is often the case in failure and anomaly investigations that data is either limited or so wide ranging that it is difficult to bring focus to a key root cause. For this reason, a disciplined approach incorporating root cause trees (Ishikawa Diagrams) is usually taken to develop and track root cause hypotheses and analyses. During the investigation, statistical tools can be used to evaluate various hypotheses of failure. However, in many cases, there is limited failure data and it is often necessary to set up accelerated life tests involving many samples in order to induce failures under controlled conditions so that a statistically significant population of failures can be obtained. Root cause is sometimes achieved only after extensive and expensive efforts to reduce the number of root cause hypotheses. Other times, root cause investigations are truncated to “most probable cause” based on the evidence available and expert opinion.","PeriodicalId":117250,"journal":{"name":"2009 IEEE Aerospace conference","volume":"1 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":"129972070","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.2009.4839405
G. Mayhew
Order n de Bruijn sequences are the period 2n binary sequences from n-stage feedback shift registers. The de Bruijn sequences have good randomness and complexity properties. The quantity of de Bruijn sequences in a weight class of the order n generating functions is an unsolved NP complete problem. Weight class distributions for small n have been obtained by exhaustive searches. This paper uses cumulative distribution function to obtain a high resolution projection of the quantity of de Bruijn sequences in each order 7 weight class. The weight class probability mass function is a shifted Binomial probability mass function which in the limit is accurately represented as a Normal probability density function scaled by a Beta probability density function. The order 7 weight class cumulative distribution function can be modeled as a weighted sum of two Normal cumulative distribution functions.
{"title":"Cumulative distribution function for order 7 de Bruijn weight classes","authors":"G. Mayhew","doi":"10.1109/AERO.2009.4839405","DOIUrl":"https://doi.org/10.1109/AERO.2009.4839405","url":null,"abstract":"Order n de Bruijn sequences are the period 2n binary sequences from n-stage feedback shift registers. The de Bruijn sequences have good randomness and complexity properties. The quantity of de Bruijn sequences in a weight class of the order n generating functions is an unsolved NP complete problem. Weight class distributions for small n have been obtained by exhaustive searches. This paper uses cumulative distribution function to obtain a high resolution projection of the quantity of de Bruijn sequences in each order 7 weight class. The weight class probability mass function is a shifted Binomial probability mass function which in the limit is accurately represented as a Normal probability density function scaled by a Beta probability density function. The order 7 weight class cumulative distribution function can be modeled as a weighted sum of two Normal cumulative distribution functions.","PeriodicalId":117250,"journal":{"name":"2009 IEEE Aerospace conference","volume":"1 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":"130080717","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.2009.4839698
D. Gaines, Paolo Belluta, J. Herman, P. Hwang, R. Mukai, Dan Porter, Byron B. Jones, E. Wood, J. Grotzinger, L. Edgar, A. Hayes, T. Hare, S. Squyres
The Mars Exploration Rover Opportunity has recently completed a two year campaign studying Victoria Crater. The campaign culminated in a close approach of Cape Verde in order to acquire high resolution imagery of the exposed stratigraphy in the cliff face. The close approach to Cape Verde provided significant challenges for every subsystem of the rover as the rover needed to traverse difficult, uncharacterised terrain and approach a cliff face with the potential of blocking out solar energy and communications with Earth. In this paper we describe the strategic analyses performed by the science and engineering teams so that we could successfully achieve the science objectives while keeping the rover safe.
{"title":"Strategic analysis for the MER Cape Verde approach","authors":"D. Gaines, Paolo Belluta, J. Herman, P. Hwang, R. Mukai, Dan Porter, Byron B. Jones, E. Wood, J. Grotzinger, L. Edgar, A. Hayes, T. Hare, S. Squyres","doi":"10.1109/AERO.2009.4839698","DOIUrl":"https://doi.org/10.1109/AERO.2009.4839698","url":null,"abstract":"The Mars Exploration Rover Opportunity has recently completed a two year campaign studying Victoria Crater. The campaign culminated in a close approach of Cape Verde in order to acquire high resolution imagery of the exposed stratigraphy in the cliff face. The close approach to Cape Verde provided significant challenges for every subsystem of the rover as the rover needed to traverse difficult, uncharacterised terrain and approach a cliff face with the potential of blocking out solar energy and communications with Earth. In this paper we describe the strategic analyses performed by the science and engineering teams so that we could successfully achieve the science objectives while keeping the rover safe.","PeriodicalId":117250,"journal":{"name":"2009 IEEE Aerospace conference","volume":"51 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":"130197485","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.2009.4839313
L. Jenkins
Space-Based Solar Power-SBSP) is a concept that has considerable potential to provide clean renewable energy. Increased population coupled with reduced natural resources represent a challenge to national and world security. The SBSP concept is to collect energy from the Sun in Earth orbit. The electrical energy is converted to microwave frequency for transmission to the surface of the Earth. There it is converted back in to electricity for use. Possible usages are base-load power, fuel conversion or direct delivery to consumers in isolated locations. The available potential of solar energy is greater than energy in petroleum reserves. The primary issue is defining the path to development of SBSP capability.
{"title":"Issues in development of space-based solar power","authors":"L. Jenkins","doi":"10.1109/AERO.2009.4839313","DOIUrl":"https://doi.org/10.1109/AERO.2009.4839313","url":null,"abstract":"Space-Based Solar Power-SBSP) is a concept that has considerable potential to provide clean renewable energy. Increased population coupled with reduced natural resources represent a challenge to national and world security. The SBSP concept is to collect energy from the Sun in Earth orbit. The electrical energy is converted to microwave frequency for transmission to the surface of the Earth. There it is converted back in to electricity for use. Possible usages are base-load power, fuel conversion or direct delivery to consumers in isolated locations. The available potential of solar energy is greater than energy in petroleum reserves. The primary issue is defining the path to development of SBSP capability.","PeriodicalId":117250,"journal":{"name":"2009 IEEE Aerospace conference","volume":"1 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":"130612530","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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