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ABSTRACT: An observation quality evaluation system for onboard dual frequency GPS is presented in this paper. We investigate how to evaluate the quality of onboard dual frequency kinematic GPS receiver using in-flight observations, and provide several indices of onboard observation quality evaluation. To come over high dynamic characteristics of onboard observations, we design an efficient method of outlier elimination and cycle slip detection. Then via linear combination of original observations, the kinematic observations noise is extracted, and the observation quality is evaluated. Further more, we provide an algorithm to compute the correlation of different types of observations, and analyze the relation between the observation quality and sightline direction. We achieve a series of reliable quality evaluation results by experiments on the data from CHAMP satellite and provide reasonable explanation. The results of CHAMP data analysis contribute to better understanding of receivers and applications of GPS.
Computing, Communication, Control, and Management, 2008. CCCM '08. ISECS International Colloquium on; 09/2008
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ABSTRACT: The stock market is a typically complex and self-interacting system that in many aspects it shows the characteristic of self-organized criticality (SOC). In the present work we mainly investigate the SOC properties of individual companies. Price volatility can be served as an analogy of "avalanche" in the classical sand-pile model and different volatility statistics have different power law behaviors. We mainly analyze the distributions of the return and its ramificate statistics, both theoretical and experimental. The empirical study of the Chinese 5-min trading data (from 2005/7/8 to 2006/2/8) shows that some volatility statistics did show significant power law behaviors while some other volatility statistics show asymptotic power law behaviors and do not accord with the classical SOC model, which might be SOC affected by noise, sub-critical or even chaos. Furthermore, we find that cumulative volatility statistics are much more significant than the original statistics and the high-order volatilty statistics present an inherent multifractality.
Natural Computation, 2007. ICNC 2007. Third International Conference on; 09/2007
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ABSTRACT: As an outcome of the overwhelming volume of Internet resources, it is necessary to research methods integrating distributed autonomous resources connected to the Internet to make them more effective and efficient. With the understanding of characteristics of internet resources, this paper will focus on solving the problem of text resource aggregation in open environment and its emergence showed during aggregation over time. We process these text resources both in space and time dimension through viewing them as an event stream evolving over time, and attempt to discover the evolutionary event patterns, furthermore, to mine the emergence of text content, such as revealing research trends in scientific literature. Experiments show that our methods can discover interesting evolutionary event patterns effectively.
Fuzzy Systems and Knowledge Discovery, 2007. FSKD 2007. Fourth International Conference on; 09/2007
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ABSTRACT: The inter-satellite baseline plays a vital role in the formation flying satellites missions. Based on the relation between the spatial states and the inter-satellite baseline, this paper erects a model to associate these two kinds of parameters. The error propagation relations are deduced in detail, which are described by the precision influence factors and error propagation matrices. Simulations are also carried out to show the baseline determination precision in some certain scenarios.
Geoscience and Remote Sensing Symposium, 2006. IGARSS 2006. IEEE International Conference on; 09/2006
