The Atmospheric Remote-sensing Infrared Exoplanet Large-survey (ARIEL) is the latest addition as the M4 mission in the ESA Cosmic Vision programme. This mission will study the chemical composition of exoplanetary atmo...
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ISBN:
(纸本)9781510636927
The Atmospheric Remote-sensing Infrared Exoplanet Large-survey (ARIEL) is the latest addition as the M4 mission in the ESA Cosmic Vision programme. This mission will study the chemical composition of exoplanetary atmospheres via high resolution, multi-wavelength spectroscopy with high photometric precision. These tasks demand highly stable pointing during operation, which is provided by a dedicated Fine Guiding Sensor (FGS) instrument. The FGS uses two Mercury Cadmium Telluride (MCT) detectors operating in the 0.5-1.95 mu m range. The centroid measurements are provided to the spacecraft forming a closed loop in the guiding. In addition, the FGS detectors are also used for science including photometric and spectral windows. The instrument contains a Data Processing Unit (DPU) with a dual core LEON-based computer running the Instrument Application Software (IASW). The software implements a large number of ECSS services to fulfill the various operating needs. The mission-specific modes cover target acquisition and tracking tasks, processing of the photometric and spectral windows as well as various calibration modes. The science data need to be compressed in a lossless manner using algorithms previously developed for the ESA missions HERSCHEL and CHEOPS. While the science data processing has only soft real-timing needs, the centroiding is critical to run and provide results as fast as possible. We present the architectural design of the software particularly highlighting the low-level software adaptations needed to support the high demands from the centroid timing. The presented overview of the design is complemented with the expected performance of the algorithms.
We present optimized performance of algorithms developed for detection of point like, visible light bursts in the sky. The algorithms based on analysis of series of consequtive images and detecting local differences b...
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ISBN:
(纸本)081945415X
We present optimized performance of algorithms developed for detection of point like, visible light bursts in the sky. The algorithms based on analysis of series of consequtive images and detecting local differences between them were tested on simulated data obtained by inserting images of stars of different magnitudes at random positions. We discuss the choice of parameters which results in the maximal detection efficiency and simultaneously keeps the number of false detections as low as possible.
We extract the chirp of an ultrashort laser pulse accurately in real-time using a simple modified auto-interferometric correlation (MOSAIC) technique. Through the use of our newly developed time-domain algorithm, chir...
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ISBN:
(纸本)0819461431
We extract the chirp of an ultrashort laser pulse accurately in real-time using a simple modified auto-interferometric correlation (MOSAIC) technique. Through the use of our newly developed time-domain algorithm, chirp information is accessible with signal-to-noise levels approaching unity. Correction algorithms have been developed to accommodate signal distortions due to bandwidth limitations, autocorrelator misalignment, and non-quadratic detector response.
The quality of an image can be evaluated by performing a psychovisual test or by using quantitative quality measures. In order to assess the performance of different halftone techniques, gray scale images are halftone...
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ISBN:
(纸本)0819408204
The quality of an image can be evaluated by performing a psychovisual test or by using quantitative quality measures. In order to assess the performance of different halftone techniques, gray scale images are halftoned in various ways and then presented to human viewers for quality evaluation. Quantitative quality criteria, such as edge correlation, mean square error and local error measures are also used for quality evaluation of the halftone images. Since the ultimate judges of image quality are human viewers, the success of these quantitative criteria as quality measures for halftones is assessed by comparing their results with the results of the psychovisual test.
In this paper, data reduction for the acquired contour is discussed. Lyche's knot-removal algorithm is introduced. For the given sets of points on the contour, we reduce the number of data points without distortin...
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ISBN:
(纸本)0819410330
In this paper, data reduction for the acquired contour is discussed. Lyche's knot-removal algorithm is introduced. For the given sets of points on the contour, we reduce the number of data points without distorting the original contour by more than a given tolerance.
The key element in the design of fast algorithms in numerical analysis and signal processing is the selection of an efficient approximation for the functions and operators involved. In this talk we will consider appro...
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ISBN:
(纸本)0819441929
The key element in the design of fast algorithms in numerical analysis and signal processing is the selection of an efficient approximation for the functions and operators involved. In this talk we will consider approximations using wavelet and multiwavelet bases as well as a new type of approximation for bandlimited functions using exponentials obtained via Generalized Gaussian quadratures. Analytically, the latter approximation corresponds to using the basis of the Prolate Spheroidal Wave functions. We will briefly comment on the future development of approximation techniques and the corresponding fast algorithms.
In practice, Multisensor systems use dissimilar sensors having different data rates. Such sensors may also have inherent delays as well as communication delays. Recently the authors developed a track fusion algorithm ...
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ISBN:
(纸本)0819424838
In practice, Multisensor systems use dissimilar sensors having different data rates. Such sensors may also have inherent delays as well as communication delays. Recently the authors developed a track fusion algorithm that attempted to account for realistic constraints of sensor fusion. The objective of this paper are two folds. First, it shows that the synchronous track fusion problem can be derived as a special case of the developed track fusion algorithm. Second, using simulated target tracks, the performance of the asynchronous track fusion (ASTF) algorithm is analyzed and compared to an existing fusion algorithm. Different sensor data rates and communication delays are used in the simulations.
Monte Carlo simulation technique is used to study photon migration in biological tissues. On a 36 mm diameter cylinder, temporal point spread function is simulated for each of the seven detectors around the model. Inf...
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ISBN:
(纸本)0819413496
Monte Carlo simulation technique is used to study photon migration in biological tissues. On a 36 mm diameter cylinder, temporal point spread function is simulated for each of the seven detectors around the model. Information such as mean-time-of-flight, differential pathlength factor, and detected photon number are recorded. Two back-projection algorithms have been proposed to reconstruct tomographic images of phantom.
An interpretation of the tracking behavior of fast RLS adaptive filters is given. It is shown that the overall performance of an RLS adaptive filter is solely dependent on the forgetting function, which is involved in...
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ISBN:
(纸本)0819406937
An interpretation of the tracking behavior of fast RLS adaptive filters is given. It is shown that the overall performance of an RLS adaptive filter is solely dependent on the forgetting function, which is involved in coefficient updating. Fast RLS adaptive filters restrict themselves to simple exponential or rectangular forgetting functions. Their tracking behavior is quite limited and sometimes even disappointing when compared to the much simpler LMS algorithm. These limitations can be circumvented with the advent of Schur RLS adaptive filters which allow the application of arbitrarily shaped forgetting functions in the coefficient updating process. Schur RLS adaptive filters are closely connected to the theory of discrete transmission lines. They are flexible in their possible configuration and share excellent structural and numerical properties, which make them highly attractive candidates for concurrent implementations. Systolic arrays of the Schur RLS adaptive filters are presented and their performance is demonstrated with a typical example.
Many applications of the eigenvalue decomposition of dense matrices are well known. This work was prompted by research in the numerical simulation of disordered electronic systems, in which one of the most common appr...
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ISBN:
(纸本)0819412767
Many applications of the eigenvalue decomposition of dense matrices are well known. This work was prompted by research in the numerical simulation of disordered electronic systems, in which one of the most common approaches is to diagonalize random Hamiltonian matrices in order to study the eigenvalues and eigenfunctions of a single electron in the presence of a random potential. In this paper, we describe an effort to implement a matrix diagonalization routine for real symmetric dense matrices on massively parallel SIMD computers, the Maspar MP-1 and MP-2 systems. Results of numerical tests and timings are also presented.
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