scholarly journals Using phase-state modelling for inferring forecasting uncertainty in nonlinear stochastic decision schemes

1999 ◽  
Vol 1 (2) ◽  
pp. 75-82 ◽  
Author(s):  
Ezio Todini
Keyword(s):  
Time Management ◽  
Phase State ◽  
A Priori ◽  
Deterministic Models ◽  
Ensemble Forecasts ◽  
Additional Information ◽  
Future Events ◽  
Expected Benefits ◽  
Posteriori Distribution ◽  
A Priori Uncertainty

The paper introduces the use of phase-state modelling as a means of estimating expected benefits or losses when dealing with decision processes under uncertainty of future events. For this reason the phase-space approach to time series, which generally aims at forecasting the expected value of a future event, is here also used to assess the forecasting uncertainty. Under the assumption of local stationarity the ensemble of generated future trajectories can be used to estimate a probability density that represents the a priori uncertainty of forecasts conditional on the latest measurements. This a priori density can then be used directly in the optimisation schemes if no additional information is available, or after deriving an a posteriori distribution in the Bayesian sense, by combining it with forecasts from deterministic models, here taken as noise-corrupted ‘pseudo-measurements’ of future events. Examples of application are given in the case of the Lake Como real-time management system as well as in the case of rainfall ensemble forecasts on the River Reno.

Method for measuring distortions of a speech signal during its transmission over a communication channel to a biometric identification system

2020 ◽  
pp. 65-72
Author(s):  
V. V. Savchenko ◽  
A. V. Savchenko
Keyword(s):  
Speech Signal ◽  
Communication Channel ◽  
Speaker Identification ◽  
A Priori ◽  
Small Samples ◽  
Practical Implementation ◽  
Identification System ◽  
New Information ◽  
Discrimination Criterion ◽  
A Priori Uncertainty

This paper is devoted to the presence of distortions in a speech signal transmitted over a communication channel to a biometric system during voice-based remote identification. We propose to preliminary correct the frequency spectrum of the received signal based on the pre-distortion principle. Taking into account a priori uncertainty, a new information indicator of speech signal distortions and a method for measuring it in conditions of small samples of observations are proposed. An example of fast practical implementation of the method based on a parametric spectral analysis algorithm is considered. Experimental results of our approach are provided for three different versions of communication channel. It is shown that the usage of the proposed method makes it possible to transform the initially distorted speech signal into compliance on the registered voice template by using acceptable information discrimination criterion. It is demonstrated that our approach may be used in existing biometric systems and technologies of speaker identification.

Detection of Changes in the Random Signal Properties by Spectral Methods Under the Conditions of A Priori Uncertainty

1999 ◽  
Vol 53 (9-10) ◽  
pp. 1-10
Author(s):  
V. A. Omel'chenko ◽  
V. V. Balabanov ◽  
B. M. Bezruk ◽  
Yu. N. Goloborod'ko
Keyword(s):  
Spectral Methods ◽  
A Priori ◽  
Random Signal ◽  
A Priori Uncertainty

Fractal analysis in biology and medicine

2020 ◽  
pp. 85-92
Keyword(s):  
Fractal Analysis ◽  
A Priori ◽  
Research Work ◽  
Structure And Function ◽  
Review Article ◽  
Living Systems ◽  
Modern Biology ◽  
Additional Information ◽  
Important Additional Information ◽  
And Function

The review article discusses the possibilities of using fractal mathematical analysis to solve scientific and applied problems of modern biology and medicine. The authors show that only such an approach, related to the section of nonlinear mechanics, allows quantifying the chaotic component of the structure and function of living systems, that is a priori important additional information and expands, in particular, the possibilities of diagnostics, differential diagnosis and prediction of the course of physiological and pathological processes. A number of examples demonstrate the specific advantages of using fractal analysis for these purposes. The conclusion can be made that the expanded use of fractal analysis methods in the research work of medical and biological specialists is promising.

TAKING INTO CONSIDERATION OF THE MULTIPLE MODE OF THE FUNCTIONING AND CHARACTERISTICS OF THE CONTROL IN RELIABILITY MODELS OF REPLACEMENT TIME SYSTEMS

2019 ◽  
Author(s):  
Iryna Kononova
Keyword(s):  
A Priori ◽  
Telecommunication System ◽  
Structural Element ◽  
Reliability Models ◽  
Quick Recovery ◽  
Reliability Indicators ◽  
A Priori Uncertainty ◽  
Control Of Parameters ◽  
Time Systems ◽  
Time Reserve

The article evaluates the reliability indicators of telecommunication system equipment, which can be represented by multi-mode objects of continuous and episodic use with a time reserve operating under conditions of a priori uncertainty. Particular attention is paid to consideration of the process of functioning of the system with a replenished time reserve. The telecommunication system includes an object represented by one structural element and used in different modes of operation. In each mode, the object can be used continuously or episodically (the object performs tasks that occur at random times), herewith only a certain part of its equipment is operating. The restoration of the facility's operation in each mode is based on the "quick" recovery scheme ("quick" recovery means that the repair time is much less than the average working time of the element between failures). Also, some cases of the transition of an object from one mode to another are considered, and the control system operates according to the method of sequential control of parameters. In this case, the system, after waiting mode, begins to analyze the first parameter of the monitored complex, then the second and so on. After analyzing the parameters, the system enters the waiting mode. These calculated ratios allow for a comprehensive assessment of the reliability of telecommunication equipment, taking into account the totality of the main factors that significantly affect the reliability of the equipment in real conditions of operation, make it possible to solve important practical problems which arise from the improvement of existing equipment and development of existing equipment.

Spatial filtering of signals with spectrum overlapping

2019 ◽  
pp. 27-33
Author(s):  
M. E. Shevchenko ◽  
A. V. Gorovoy ◽  
S. N. Solovyov
Keyword(s):  
Antenna Arrays ◽  
A Priori ◽  
Spatial Filtering ◽  
Spatial Filter ◽  
Radio Sources ◽  
Probability Of Error ◽  
Shift Keying ◽  
A Priori Uncertainty

The paper considers the spatial filtering methods of signals with spectrum overlapping under conditions of a priori uncertainty of the directions of arrival from radio sources. The estimates of the directions of signals arrival obtained by ESPRIT or MUSIC are used in order to build a spatial filter. It is shown that when using ESPRIT, unlike MUSIC, an additional calculations of filter coefficients based on estimates of the directions of signals arrival are not required, and the quadrature components of the signals are formed simultaneously with estimates of the direction of their arrival. The probability of error performances of minimum shift keying signals which were divided by spatial filtering on the basis of ESPRIT and MUSIC using seven-element circular and angular antenna arrays are given.

Machine vision-based sensing for helicopter flight control

Robotica ◽  
2000 ◽  
Vol 18 (3) ◽  
pp. 299-303 ◽  
Author(s):  
Carl-Henrik Oertel
Keyword(s):  
Machine Vision ◽  
Measurement System ◽  
Flight Control ◽  
A Priori ◽  
Image Data ◽  
Two Dimensional ◽  
Position Measurement ◽  
Additional Information ◽  
Helicopter Flight ◽  
Template Tracking

Machine vision-based sensing enables automatic hover stabilization of helicopters. The evaluation of image data, which is produced by a camera looking straight to the ground, results in a drift free autonomous on-board position measurement system. No additional information about the appearance of the scenery seen by the camera (e.g. landmarks) is needed. The technique being applied is a combination of the 4D-approach with two dimensional template tracking of a priori unknown features.

scholarly journals Validation of the IASI FORLI/Eumetsat ozone products using satellite (GOME-2), ground-based (Brewer-Dobson, SAOZ) and ozonesonde measurements

2018 ◽  
Author(s):  
Anne Boynard ◽  
Daniel Hurtmans ◽  
Katerina Garane ◽  
Florence Goutail ◽  
Juliette Hadji-Lazaro ◽  
...  
Keyword(s):  
A Priori ◽  
Long Term Stability ◽  
Comparison Results ◽  
Independent Observations ◽  
Mean Differences ◽  
A Priori Uncertainty ◽  
The Tropics ◽  
Global Mean

Abstract. This paper assesses the quality of IASI/Metop-A (IASI-A) and IASI/Metop-B (IASI-B) ozone (O3) products (total and partial O3 columns) retrieved with the Fast Optimal Retrievals on Layers for IASI Ozone (FORLI-O3) v20151001 software for nine years (2008–2017) through an extensive inter-comparison and validation exercise using independent observations (satellite, ground-based and ozonesonde). IASI-A and IASI-B Total O3 Columns (TOCs) are generally consistent, with a global mean difference less than 0.3 % for both day- and nighttime measurements, IASI-A being slightly higher than IASI-B. A global difference less than 2.4 % is found for the tropospheric (TROPO) O3 column product (IASI-A being lower than IASI-B), which is partly due to a temporary issue related to IASI-A viewing angle in 2015. Our validation shows that IASI-A and IASI-B TOCs are consistent with GOME-2, Dobson, Brewer and SAOZ retrieved ones, with global mean differences in the range 0.1–2 % depending on the instruments. The IASI-A and ground-based TOC comparison for the period 2008–July 2017 shows good long-term stability (negative trends within 3 % decade−1). The comparison results between IASI-A and IASI-B against smoothed ozonesonde partial O3 columns vary in altitude and latitude, with maximum standard deviation for the 300–150 hPa column (20–40 %) due to strong ozone variability and a priori uncertainty. The worst agreement with the ozonesondes and with UV-vis retrieved TOC [satellite and ground] is found at the southern high latitudes. Compared to ozonesonde data, IASI-A and IASI-B O3 products overestimate the O3 abundance in the stratosphere (up to 20 % for the 150–25 hPa column) and underestimates the O3 abundance in the troposphere (within 10 % for the mid-latitudes and ~ 18 % for the tropics). Based on the period 2011–2016, non-significant drift is found for the northern hemispheric tropospheric columns while a small drift prevails for the period before 2011.

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