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Synthesis of magnetic material images using SAR models with irregular neighbour sets

ELECTRONICS LETTERS 2000年第1期36卷 26-27页

作者： Shang, C Titterington, DM Univ Glasgow IBLS Div Neurosci & Biomed Syst Glasgow G12 8QQ Lanark Scotland Univ Glasgow Dept Stat Glasgow G12 8QQ Lanark Scotland

The application of SAR models to the synthesis of magnetic material images is presented. The effects of the structure of neighbour sets on the statistical properties of synthesised images are investigated. Supported by the content-based image retrieval technique, the work demonstrates that using a neighbour set with its shape corresponding to the orientations and coarseness of the underlying texture allows the generation of realistic synthetic images.

关键词： Mathematics computing Information retrieval techniques statistical properties SAR models coarseness content-based image retrieval technique synthesised images irregular neighbour sets underlying texture orientations magnetic material image synthesis realistic synthetic image generation surface texture probability and statistics content-based retrieval magnetic materials Computer vision and image processing techniques statistical analysis

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Optimisation of InGaAs infrared photovoltaic detectors

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IEE PROCEEDINGS-OPTOELECTRONICS 1999年第4期146卷 173-176页

作者： Piotrowski, J Kaniewski, J Vigo Syst PL-01389 Warsaw Poland Inst Electron Phys PL-02668 Warsaw Poland

The ultimate signal-to-noise performance of infrared photodetectors is limited by the statistical nature of the thermal generation and recombination of charge carriers. Band-to-band Auger processes dominate in a high quality InGaAs used for photovoltaic detector operating at room temperature. The performance of devices operating in the 2-3.4 mu m spectral range has been analyzed theoretically Homo- and heterostructure devices have been considered. The use of n(+)np(+) (or n(+)pp(+)) with heavily doped regions has been found to prevent the recombination of photogenerated carriers at contacts, but the bulk thermal generation in the heavily doped regions will significantly reduce the performance of the devices.

关键词： Doping and implantation of impurities Auger effect Photodetectors photovoltaic detector InGaAs infrared photovoltaic detector optimisation photodielectric effects III-V semiconductors statistical analysis heterostructure devices 2 to 3.4 mum thermal generation semiconductor doping Photoconduction and photovoltaic effects gallium arsenide ultimate signal-to-noise performance statistical nature homostructure devices infrared photodetectors Thermal instruments and techniques photovoltaic effects InGaAs Photoconducting materials and properties infrared detectors photogenerated carriers band-to-band Auger processes bulk thermal generation high quality InGaAs Detection of radiation (bolometers, photoelectric cells, i.r. and submillimetre waves detection) indium compounds Electron-surface impact: Auger emission probability and statistics heavily doped regions Semiconductor doping charge carrier recombination probability theory, stochastic processes, and statistics room temperature

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Impact of polarisation mode dispersion on the statistics of Q factor in optical transmission systems

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ELECTRONICS LETTERS 2000年第16期36卷 1400-1402页

作者： Beltrame, D Matera, F Settembre, M Galtarossa, A Pizzinat, A Favre, F Le Guen, D Henry, M Fdn Ugo Bordoni I-00142 Rome Italy Univ Padua I-35131 Padua Italy France Telecom R&D F-22307 Lannion France

The authors calculate the probability density function of the Q factor for optically amplified transmission IM-DD systems, in the presence of a randomicity given by the polarisation mode dispersion. Theoretical and ex... 详细信息

关键词： optically amplified transmission IM-DD systems optical fibre dispersion probability density function Q factor statistics optical fibre communication randomicity Fibre optics optical transmission systems polarisation mode dispersion Optical communication probability and statistics probability optical soliton field trial Q-factor optical fibre polarisation statistical analysis

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AMPLITUDE FLUCTUATION OF UNDERWATER SIGNALS AND ITS EFFECT ON BIT-ERROR probability OF UNDERWATER DATA-TRANSMISSION SYSTEMS

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PROCEEDINGS OF THE INSTITUTION OF ELECTRICAL ENGINEERS-LONDON 1977年第2期124卷 115-119页

作者： ANDREWS, RS TURNER, LF UNIV LONDON IMPERIAL COLL SCI & TECHNOLDEPT ELECT ENGNLONDON SW7 2BTENGLAND

Two models are proposed for the probability density function (p.d.f.) of the amplitude fluctuations that arise when short-duration sound pulses are transmitted under shallow-water conditions. The models are derived for the conditions in which the prevailing surface-wind directions are parallel and perpendicular to the line of transmission. The probability density functions obtained from the models are compared with experimentally measured p.d.f.s and are found to be in excellent agreement. The models are then used to predict the bit-error probability in a binary underwater amplitude-shift-keyed (a.s.k) data-transmission system and the results are compared with experimentally measured error probabilities. It is found that the measured error probabilities lie between the values computed using the p.d.f. models and it is conjectured that the proposed models provide approximate upper and lower bounds to the average error probability in a.s.k. underwater data-transmission systems. Finally, the p.d.f. models are used to compute new receiver-operating-characteristic (r.o.c.) curves.

关键词： digital communication systems probability Other data transmission amplitude fluctuations data communication systems probability and statistics underwater signals underwater sound bit error probability underwater data transmission systems probability density function amplitude shift keyed

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Extreme value statistics for novelty detection in biomedical data processing

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IEE PROCEEDINGS-SCIENCE MEASUREMENT AND TECHNOLOGY 2000年第6期147卷 363-367页

作者： Roberts, SJ Univ Oxford Dept Engn Sci Robot Res Grp Oxford OX1 3PJ England

Extreme value theory (EVT) is a branch of statistics which concerns the distributions of data of unusually low or high value i.e. in the tails of some distribution. These extremal points are important in many applications as they represent the outlying regions of normal events against which we may wish to define novel events. The use of such novelty detection approaches is useful for analysis of data for which few exemplars of some important class exist, for example in medical screening. It is shown that a principled approach to the issue of novelty detection may be taken using extreme value statistics.

关键词： Signal detection statistical analysis Digital signal processing Biology and medical computing distribution tails biomedical data processing outlying regions data distributions General, theoretical, and mathematical biophysics medical signal processing Biomedical measurement and imaging unusually high value novelty detection Biomedical engineering probability and statistics medical signal detection unusually low value extreme value statistics normal events probability theory, stochastic processes, and statistics

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Spatial holeburning in second-order excitation probability distribution for densely erbium-doped fibres

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ELECTRONICS LETTERS 1999年第14期35卷 1191-1193页

作者： Helmfrid, S Bremberg, D Jaskorzynska, B Philipsen, JL Royal Inst Technol Dept Elect Lab Photon & Microwave Engn S-16440 Kista Sweden Tech Univ Denmark COM Ctr DK-2800 Lyngby Denmark

The increase in upconversion rate in strongly erbium-doped fibres induced by an enhanced energy redistribution is investigated and explained in terms of spatial holeburning in the second-order excitation probability distribution. It is shown that the equalisation of decay curves, where the initial population has been prepared in different ways, is caused by an increased upconversion rate for closely located excited ions.

关键词： strongly erbium-doped fibres Optical transient phenomena, self-induced transparency, optical saturation and related effects optical pumping Fibre lasers and amplifiers fluorescence erbium Impurity and defect absorption in insulators excited states probability optical hole burning densely erbium-doped fibres probability theory, stochastic processes, and statistics upconversion rate spatial holeburning enhanced energy redistribution increased upconversion rate Fibre optics impurity absorption spectra second-order excitation probability distribution optical fibre amplifiers Optical saturation and related effects closely located excited ions Optical fibre testing and measurement of fibre parameters decay curve equalisation Photoluminescence in other inorganic materials optical fibre testing probability and statistics

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Comments on "Generalized Box-Muller Method for Generating q-Gaussian Random Deviates"

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IEEE TRANSACTIONS ON INFORMATION THEORY 2021年第10期67卷 6785-6789页

作者： Nelson, Kenric P. Thistleton, William J. Photrek LLC Watertown MA 02472 USA SUNY Polytech Inst Utica NY 13502 USA

The generalized Box-Muller algorithm provides a methodology for generating q-Gaussian random variates, which generalizes the Gaussian (q = 1). The parameter -infinity < q <= 3 is related to the shape of the tail decay;q < 1 for compact-support including parabola (q = 0);1 < q <= 3 for heavy-tail including Cauchy (q = 2). This addendum clarifies the transformation q' = 3q-1/q+1 within the algorithm is due to a difference in the dimensions d of the generalized logarithm and the generalized distribution. The transformation is clarified by the decomposition of q = 1 + 2 kappa/1+d kappa, where the shape parameter -1 < kappa <= infinity quantifies the magnitude of the deformation from exponential. A simpler specification for the generalized Box-Muller algorithm is provided using the shape of the tail decay.

关键词： Random variables probability and statistics information theory complex systems nonlinear Pareto

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Estimation of BER performance and cascadability of wavelength converters based on cross-gain modulation in semiconductor optical amplifiers

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IEE PROCEEDINGS-OPTOELECTRONICS 2000年第2期147卷 133-137页

作者： Obermann, K Petermann, K Tech Univ Berlin Inst Hochfrequenztech D-10587 Berlin Germany

The transmission of the input intensity noise for wavelength converters based on cross-gain modulation in semiconductor optical amplifiers is investigated theoretically It is shown how the noise statistics change due to the nonlinear transmission function and how bit error rates can be estimated. The power penalty strongly depends on the wavelength shift and can be 5.2 dB at 2.5 Gbit/s when the wavelength is up-shifted by 20 nm. When the extinction ratio is enhanced by the converter, even negative penalties are obtainable. In agreement with computer simulations, the input dynamic range is determined to be at least 13 dB. Furthermore, it is demonstrated that at 2.5 Gbit/s, 62 wavelength converters can be cascaded when each converter is operated so that the extinction ratio is preserved. However, when the wavelength is alternatively down-and up-shifted by 15 nm, less than eight stages are cascadable.

关键词： negative penalties 2.5 Gbit/s optical frequency conversion statistical analysis down-shifted extinction ratio laser theory wavelength shift up-shifted optical wavelength converters computer simulations BER performance Multiplexing and switching in optical communication bit error rates power penalty semiconductor device models cascadable wavelength converters laser noise cascadability wavelength division multiplexing nonlinear transmission function electro-optical modulation Lasing action in semiconductors cross-gain modulation semiconductor optical amplifiers probability and statistics Semiconductor lasers Optical harmonic generation, frequency conversion, parametric oscillation and amplification input dynamic range Semiconductor device modelling, equivalent circuits, design and testing probability theory, stochastic processes, and statistics noise statistics

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SUMMATION OF HARMONICS WITH RANDOM PHASE ANGLES

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PROCEEDINGS OF THE INSTITUTION OF ELECTRICAL ENGINEERS-LONDON 1972年第11期119卷 1643-&页

作者： SHERMAN, WG Engineering Mathematics & Computation Department GEC Machines Ltd. Rugby UK

The magnitude of the sum of a number of harmonics, of the same order but with random phase angle, is derived, subject to certain assumptions regarding the phase distribution. Computation of the net magnitude is carried out for different types of individual harmonic amplitudes. When the number of individual harmonics is greater than about ten, it is shown that simplified expressions for the sum may be used. These lead to a simple approach, based on r.m.s. values, to the problem of determining an assessed level of harmonic content which would have a specific probability of being exceeded. Consideration is also given to the situation when just one or two harmonics are dominant, and a consequent simplification of an assessed level. The main results apply for instantaneous values of the net magnitude, but some subsidiary results given an indication of the likely behaviour over a continuous period of time.

关键词： probability random phase angles probability and statistics harmonics summation

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PROBABILISTIC APPROACH FOR POWER SYSTEM DYNAMIC STABILITY STUDIES

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IEE PROCEEDINGS-C GENERATION TRANSMISSION AND DISTRIBUTION 1981年第5期128卷 295-301页

作者： BRUCOLI, M TORELLI, F TROVATO, M Istituto Elettrotecnico Facoltà di Ingegneria Università degli Studi di Bari Bari Italy

In the paper, the nondeterministic nature of electric-power-system parameters has been taken into account to draw stability limit curves on a capability chart. The results look interesting, from a practical point of view, and show that a deterministic model is unrealistic when the system is operating near its dynamic stability limit. In this case, a probabilistic approach is the most feasible alternative. The statistics of locations of system eigenvalues in the complex plane have also been evaluated

关键词： stability eigenvalues and eigenfunctions dynamic stability studies system eigenvalues power systems stability limit curves power system complex plane probabilistic approach statistics probability and statistics dynamic response Stability in control theory Power system management, operation and economics

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