Direction Finding of Ionospheric Formation with Small-Scale Inhomogeneities Based on GPS Monitoring’s Data Processing

2020 ◽  
pp. 480-487
Author(s):  
V. P. Pashintsev ◽  
V. A. Tsimbal ◽  
A. F. Chipiga ◽  
M. V. Peskov ◽  
M. A. Senokosov
Keyword(s):  
Data Processing ◽  
Direction Finding ◽  
Small Scale

scholarly journals COSMIC Radio Occultation Processing: Cross-Center Comparison and Validation

2011 ◽  
Vol 28 (6) ◽  
pp. 737-751 ◽  
Author(s):  
Michael E. Gorbunov ◽  
A. V. Shmakov ◽  
Stephen S. Leroy ◽  
Kent B. Lauritsen
Keyword(s):  
Data Processing ◽  
Radio Occultation ◽  
Weather Prediction ◽  
Processing System ◽  
Fourier Integral ◽  
Small Scale ◽  
Cosmic Radio ◽  
Structural Uncertainty ◽  
Height Range ◽  
The Tropics

Abstract A radio occultation data processing system (OCC) was developed for numerical weather prediction and climate benchmarking. The data processing algorithms use the well-established Fourier integral operator–based methods, which ensure a high accuracy of retrievals. The system as a whole, or in its parts, is currently used at the Global Navigation Satellite System Receiver for Atmospheric Sounding (GRAS) Satellite Application Facility at the Danish Meteorological Institute, German Weather Service, and Wegener Center for Climate and Global Change. A statistical comparison of the inversions of the Constellation Observing System for Meteorology, Ionosphere and Climate (COSMIC) data by the system herein, University Corporation for Atmospheric Research (UCAR) data products, and ECMWF analyses is presented. Forty days of 2007 and 2008 were processed (from 5 days in the middle of each season) for the comparison of OCC and ECMWF, and 20 days of April 2009 were processed for the comparison of OCC, UCAR, and ECMWF. The OCC and UCAR inversions are consistent. For the tropics, the systematic difference between OCC and UCAR in the retrieved refractivity in the 2–30-km height interval does not exceed 0.1%; in particular, in the 9–25-km interval it does not exceed 0.03%. Below 1 km in the tropics the OCC – UCAR bias reaches 0.2%, which is explained by different cutoff and filtering schemes implemented in the two systems. The structure of the systematic OCC – ECMWF difference below 4 km changes in 2007, 2008, and 2009, which is explained by changes in the ECMWF analyses and assimilation schemes. It is estimated that in the 4–30-km height range the OCC occultation processing system obtains refractivities with a bias not exceeding 0.2%. The random error ranges from 0.3%–0.5% in the upper troposphere–lower stratosphere to about 2% below 4 km. The estimate of the bias below 4 km can currently be done with an accuracy of 0.5%–1% resulting from the structural uncertainty of the radio occultation (RO) data reflecting the insufficient knowledge of the atmospheric small-scale structures and instrumental errors. The OCC – UCAR bias is below the level of the structural uncertainty.

scholarly journals Observation of continuum radiations from the Cluster fleet: first results from direction finding

2004 ◽  
Vol 22 (7) ◽  
pp. 2607-2624 ◽  
Author(s):  
P. M. E. Décréau ◽  
C. Ducoin ◽  
G. Le Rouzic ◽  
O. Randriamboarison ◽  
J.-L. Rauch ◽  
...  
Keyword(s):  
Wave Vector ◽  
Source Region ◽  
Direction Finding ◽  
Propagation Path ◽  
Small Scale ◽  
Frequency Range ◽  
Data Set ◽  
Continuum Radiation ◽  
Spin Plane ◽  
Rich Data

Abstract. The Cluster fleet offers the first possibility of comparing non-thermal terrestrial continuum radiation from similarly equipped nearby observation points. A very rich data set has already been acquired on the Cluster polar orbit, between 4 and 19 Earth radii geocentric distances, and preliminary analysis has been carried out on these emissions. We focus in this paper on direction finding performed from all four spacecraft as a means to locate the position of the sources of this continuum radiation. Directions are derived from spin modulation properties, under the usual analysis assumptions of the wave vector of the radiation lying in the plane containing the spin axis and the antenna position at electric field minimum. All the spin axes of the four Cluster spacecraft are aligned perpendicular to the ecliptic, thus the aligned spacecraft antenna spin planes provide redundant 2-D views of the propagation path of the radiation and source location. Convincing 2-D triangulation results have been obtained in the vicinity of the source region. In addition, the out of spin plane component of the wave vector reveals itself to a certain extent through directivity characteristics compared at different distances of the spin plane to the ecliptic. The four case events studied (two of them taken near apogee, the other two near perigee) have confirmed general properties derived from previous observations: trapping in the lower frequency range, radiation escaping into the magnetosheath region in the higher frequency range. All propagation directions are compatible with source positions in the plasmapause region, however, at a significant distance from the equator in one case. Our observations have also revealed new properties, like the importance of small-scale density irregularities in the local amplification of continuum radiation. We conclude that more detailed generation and propagation models are needed to fit the observations.

scholarly journals METHODS OF BUILDING A MODEL OF USER BEHAVIOR

2020 ◽  
Vol 2 (1) ◽  
pp. 43-51
Author(s):  
N. B. Shakhovskaya Shakhovskaya ◽  
◽  
N. I. Melnykova ◽  
Keyword(s):  
Data Analysis ◽  
Data Processing ◽  
Large Scale ◽  
Clustering Algorithms ◽  
Free Form ◽  
Small Scale ◽  
Clustering Methods ◽  
User Behaviour ◽  
Input Parameters ◽  
Scale Data

The number of clustering methods and algorithms were analysed and the peculiarities of their application were singled out. The main advantages of density based clustering methods are the ability to detect free-form clusters of different sizes and resistance to noise and emissions, and the disadvantages include high sensitivity to input parameters, poor class description and unsuitability for large data. The analysis showed that the main problem of all clustering algorithms is their scalability with increasing amount of processed data. The main problems of most of them are the difficulty of setting the optimal input parameters (for density, grid or model algorithms), identification of clusters of different shapes and densities (distribution algorithms, grid-based algorithms), fuzzy completion criteria (hierarchical, partition and model-based). Since the clustering procedure is only one of the stages of data processing of the system as a whole, the chosen algorithm should be easy to use and easy to configure the input parameters. Results of researches show that hierarchical clustering methods include a number of algorithms suitable for both small-scale data processing and large-scale data analysis, which is relevant in the field of social networks. Based on the data analysis, information was collected within fill a smart user profile. Much attention is paid to the study of associative rules, based on which an algorithm for extracting associative rules is proposed, which allows to find statistically significant rules and to look only for dependencies defined by a common set of input data, and has high computational complexity if there are many classification rules. An approach has been developed that focuses on creating and understanding models of user behaviour, predicting future behaviour using the created template. Methods of modelling pre-processing of data (clustering) are investigated and regularities of planning of meetings of friends on the basis of the analysis of daily movement of people and their friends are revealed. Methods of creating and understanding models of user behaviour were presented. The k-means algorithm was used to group users to determine how well each object lay in its own cluster. The concept of association rules was introduced; the method of search of dependences is developed. The accuracy of the model was evaluated.

scholarly journals Data processing for a small-scale long-term coastal ocean observing system near Mobile Bay, Alabama

2016 ◽  
Vol 3 (12) ◽  
pp. 510-522 ◽  
Author(s):  
Mimi W. Tzeng ◽  
Brian Dzwonkowski ◽  
Kyeong Park
Keyword(s):  
Data Processing ◽  
Coastal Ocean ◽  
Small Scale ◽  
Mobile Bay ◽  
Ocean Observing

Improvements in L2F Anemometry Technique for Inter-Blade Investigations in High-Speed Turbomachinery

1998 ◽  
Author(s):  
André Vouillarmet ◽  
Isabelle Trebinjac
Keyword(s):  
Data Processing ◽  
High Speed ◽  
Time Measurement ◽  
Acquisition Time ◽  
Small Scale ◽  
Rotating Blade ◽  
Measurement Uncertainties ◽  
Synchronized Measurements

This paper presents some problems inherent in the application of a laser two-focus anemometry technique to measurement in high-speed small-scale compressors. Improvements in data processing are described, in relation to reducing the acquisition time. Measurement uncertainties and their possible estimation are discussed. An optimized blade pitch partition during synchronized measurements within rotating blade passages is presented using a prediction of shadow zones. Two examples highlight the resulting benefits both in terms of reduction of the acquisition time and improvement of the azimuthal resolution.

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