The article deals with the problem of mathematical modeling of correlated vector of failures that can occur in navigation system. The modeling problem is considered for the case of two-dimensional distribution. This distribution corresponds to the event, when failure of whole navigation system occurs only in case of simultaneous failures of two structural units of the system. The article presents several methods of exponential correlated field formation. The modeling results can be used in case of design of operation strategy according to the condition with control of diagnostic variables to determine the optimal time interval for preventive maintenance action realization.

Correlated Failures Analysis in Navigation System

: Many simulation scenarios attempt to seek a balance between model fidelity and computational efficiency. Unfortunately, scenario realism and model level of detail are often reduced or eliminated due to the complexity of experimental design and corresponding limitations of computational power. Such simplifications can produce misleading results. For example, Radar Cross Section (RCS)effects in response to time-varying target aspect angle are dominant yet often ignored. This work investigates a new approach. A hybrid, high-fidelity sensor model can be achieved by using a Time-Step (TS) approach with precomputed a temporal response factors(such as RCS), each situated on active simulation entities that interact within an overall Discrete Event Simulation (DES) framework. This work further applies regression analysis to the cumulative results of 1,281 design points multiplied by 100 replications each to provide additional insight from massive results. Through a rigorous cross-validation (CV) for ensuring proper model selection, this new methodology adapts the best aspects of temporal control by each simulation approach, integrating multiple high-fidelity physically based models in a variety of tactical scenarios with tractable computational complexity. The meta-model generates statistically identical results as the baseline hybrid sensor model in mean with higher variation. This outcome sensor model performs in an efficient DES architecture by predicting only probability of detection (Pd) and time-to-detect (TTD) of the targets with the consideration of the range and the aspect relationship between the sensor and the target. The range and the aspect factors were ignored in current existing DES sensor models due to the overly simplified detection algorithm and the constraint of modeling complexity.

Hybrid High-Fidelity Modeling of Radar Scenarios Using Atemporal, Discrete-Event, and Time-Step Simulation

Maintenance accounts for approximately 20% of the operational cost of aircraft; a margin higher than cost associated with fuel, crew, navigation, and landing fees. A significant percentage of maintenance cost is attributed to failures of aircraft components and systems. These failures are random and provide a database which can further be analyzed to aid decision-making for maintenance optimization. In this paper, stochastic mathematical models which can potentially be used to optimize maintenance task intervals of aircraft systems are developed. The initial data for this research are diagnostic variables and reliability parameters which formed the basis for selecting the probability density function for time between failures according to the exponential and Erlang models. Based on the probability density functions, the efficiency of the maintenance processes was calculated using average operational cost per unit time. The results of the analysis were further tested using the Monte Carlo simulation method and the findings are highlighted in this paper. The simulation results compared favorably with analytical results obtained using already existing Monte Carlo techniques to about 82% accuracy. The proposed mathematical optimization models determine the optimal aircraft maintenance task interval which is cost effective while considering safety and reliability requirements; our results can also be applied during the development, design, and operation phases of aircraft systems.

Optimization of Maintenance Task Interval of Aircraft Systems

The operation system determines the efficiency of radio equipment intended use. The operation system includes radio equipment, documentation, operational resources, personnel, processes, data processing algorithms, etc. The operation process is associated with conditions of priori uncertainty of models, parameters, external factors, etc. The main element for monitoring is technical condition of radio equipment. In general case this condition can deteriorate. The problems of technical condition deterioration analysis can be considered in terms of changepoint study. This paper concentrates on the problem of synthesis and analysis of method for changepoint detection during radio equipment operation. The detection algorithm is constructed based on Neyman-Pearson criterion with sample size accumulation. During algorithm synthesis the thresholds were calculated according to Bellman’s approach. The problem of synthesis and analysis was solved by two methods: analytically and according to statistical modelling. The efficiency measures for this algorithm are the probability of correct detection and mean time of decision making. The proposed algorithm has advantages in mean time of decision making compared with CUSUM detection method.

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Method for Changepoint Detection With Sample Size Accumulation During Radio Equipment Operation

The paper concentrates on the problem of synthesis and analysis of a new method for the mode estimation for small and medium sample size. The synthesis was carried out on the basis of quadratic parabola approximation of functionally transformed statistics of the ordered sample. The analysis was carried out by statistical modeling with subsequent comparison with the classical Pearson method.

New Method of Mode Estimation for Small and Medium Samples

The statistical simulation systems which are created for the efficient solving of target detection tasks need to have special signal simulation complex. The simulation methods that can be used as the base of such complex for the pulse radar signals and clutters simulation are considered. The system that uses such algorithms is realized and demonstrates the efficiency of described methods.

http://ieeexplore.ieee.org/iel7/6574720/6581630/06581707.pdf

Signal modeling for the efficient target detection tasks

A new way that can be used to provide special capabilities for radar signal processing systems is considered. Those capabilities can be achieved for computerized signal processing systems using script languages. Presented conception allows automates the routine operations that should be executed one-by-one by a human operator; it also allows configuring the radar simulator according to the tasks that arise during the radar operation. The system that uses such conception is realized and demonstrates the efficiency of described methods.

Radar simulation system managed by script language

Aviation security services have significant value for aviation safety. Aviation security services include personnel and technical equipment for dangerous and prohibited object detection. The X-ray screening system is the main equipment for baggage contain determining. The X-ray security devices give the possibility to detect weapons, including handguns, knives, and others. The high value of the probability of false detection of X-ray screening systems requires the development of new methods of image processing. Therefore, this paper concentrates on the synthesis and analysis of methods for handgun recognition while operating the X-ray screening system. The synthesis is based on a special image processing technique using a comparison of verified images with etalon images. During this, we use the correlation coefficient to determine verified object similarity with etalons inside the database and define their mutual rotation and resizing. The analysis is associated with computer modeling for estimating probabilistic characteristics of method efficiency.

S. V. Migel

Papers

Signal modeling for the efficient target detection tasks

Radar simulation system managed by script language

Correlation Method of Dangerous Objects Detection for Aviation Security Systems