Preventive Maintenance of a k-out-of-n System with Applications in Subsea Pipeline Monitoring

Environmental safety issues are of particular importance when we design and operate underwater transport systems. To ensure the transport systems function safely, special systems to monitor their condition are being created. Underwater pipeline monitoring systems should continuously operate to detect and prevent emergency and pre-emergency situations in a timely manner. The purpose of this article is to demonstrate the possibility of using a mathematical model of a k-out-of-n system to support decision-making in the preventive maintenance of an unmanned underwater vehicle to monitor the condition of a subsea pipeline. The novelty and feature of this study are that we investigate a strategy of preventive maintenance for a model of a k-out-of-n system, where failures depend not only on the number but also on the location of the failed components in the system. The method to solve this problem, based on the distribution of the members of the variational series of the failing components, is also new. Since the distributions of the system component lifetimes are usually known with an accuracy of only one or two moments, we paid special attention to how sensitive the decision making about preventive maintenance is to the shape of the distributions. Numerical examples are conducted in order to support the theoretical investigations of the paper. The results of the study are applied to specific equipment to monitor the state of the outer surface of the pipeline.

FORMULATION OF A METHOD OF RELIABILITY ASSESSMENT FOR CONSTRUCTIONS ON THE BASIS OF A COMBINATION OF STATISTICAL MODELING AND NUMERICAL METHODS OF STRESS EVALUATION

In this paper, methods for estimating the reliability of constructions are considered. The formulation of a method for estimating the reliability of the design based on a combination of statistical modeling and numerical methods for evaluating stresses is given. The method is based on a "load – bearing capacity" model, which takes into account both stochasticity of mechanical properties of construction materials, randomness of geometric characteristics, and loads of a probabilistic nature. This new method is a system of n nested cycles. The number of governing parameters n depends on the design. The load variation series is calculated in the body of the internal cycle. The load is calculated numerically in terms of stresses using the finite element method. Any commercial solver such as Nastran, Ansys, or Abaqus can be used for this purpose. The probability of failure-free operation (reliability) is calculated involving the variational series of loads and load-carrying ability. For this purpose, the formalized estimation method based on empirical distributions is used. Fundamentals of the latter are available in the monograph "Reliability in Engineering Design" written by Kapur K.C. and Lamberson L.R.. A primary function of the proposed method is to evaluate the probability of failure-free operation of constructions under stationary or quasi-stationary random loads.

The untrue wooland its relationship with productivity indicators of tauric-tailed lambs of the ascanian fi nefl eece breed

The task of development of thin-wool sheep breeding of Ukraine at the present stage is to increase productivity, improve the quality of wool and reduce the cost of production of sheep. The untrue wool is one of the important qualities of wool, it is established by its connection with the physical and technological properties of wool, the morphological and histological structure of the skin and wool fibers. It is also interrelated with other economic and useful features and is an indicator taken into account in breeding and breeding work.The untrue wool is the subject of many scientific studies. To understand and determine the role of toning is not enough simple definition of the arithmetic mean diameter or aggregate fiber composition of wool. It is necessary, at least, to study the variational series of toning and its homogeneity. The main task of the work was to carry out an analysis of performance indicators of Tauride-type larvae of Ascanian fine-grained breed of different origin and the presence of fibers with different tint of wool and its interconnection with the main breeding grounds. The research was conducted in accordance with the results of the 2018 bonus in the conditions of DPKD "Askaniiske" of the Kherson region. For analysis, the number of lines of 224, 369 and 0058 was allocated. Each analyzed lamb line was divided into three groups based on tint of wool. Animals of 80, 70 and 64 were identified. It has been established that the experimental population of lambs of lines 369 and 0058 is recommended to be used to improve the parameters of live weight and the netting of wool. To improve the output of the blown fiber, you can use analogue lines 0058 and 224, and to increase the length of wool - animals line 369, taking into account the tonicity of wool. At the same time, take into account the correlation coeffi cients obtained when conducting breeding and breeding work with the breed. Key words: sheep of the Ascanian fine-fleeced breed of the Taurus type, line, selection signs, productivity, untrue wool, live weight, interrelation.

Wavelet Thresholding Risk Estimate for the Model with Random Samples and Correlated Noise

Signal de-noising methods based on threshold processing of wavelet decomposition coefficients have become popular due to their simplicity, speed, and ability to adapt to signal functions with spatially inhomogeneous smoothness. The analysis of the errors of these methods is an important practical task, since it makes it possible to evaluate the quality of both methods and equipment used for processing. Sometimes the nature of the signal is such that its samples are recorded at random times. If the sample points form a variational series based on a sample from the uniform distribution on the data registration interval, then the use of the standard threshold processing procedure is adequate. The paper considers a model of a signal that is registered at random times and contains noise with long-term dependence. The asymptotic normality and strong consistency properties of the mean-square thresholding risk estimator are proved. The obtained results make it possible to construct asymptotic confidence intervals for threshold processing errors using only the observed data.

Theory of statistics

The textbook deals with a wide range of issues of statistical methodology: the organization of statistical observation, data processing and analysis. Special attention is paid to statistical methods of analysis of variational series and series of dynamics, selective observation, study of correlation, index method. The Appendix contains the basic formulas and mathematical tables used in the analysis of statistical data and testing various hypotheses. For students and teachers of economic universities and faculties.

Economic and statistical modeling of the value of urban real property (using the example of Tyumen city, Russia)

The article presents the results on the derivation of an empirical formula of the relationship between the price of apartments and their area in different planning districts of the city of Tyumen, Russia. Economic and mathematical modeling was performed on the basis of analysis of variance, analysis of variational series, regression and correlation analyses. In a specific mathematical form, methods of mathematical statistics allowed answering a wide range of questions about the influence of various factors on the value of primary real property.

THE USE OF STATISTICAL CRITERIA FOR EVALUATION TEST OF DATA ON PROPERTIES OF INORGANIC SUBSTANCES

Three statistical criteria were compared on the basis of the sampling of chemical data in the article. When the criteria were compared, the level of significance was taken as equal to 0.05, because this value is most often used in the technical calculations. Evaluation of data on the one-sided outliers of variational series was carried out by using statistical criteria. With the help of Grubbs criterion for checking variation series, outliers were found neither on the right nor on the left. Further examination of the data with the use of three-sigma rule also showed no outliers. The latest statistical criterion used to detect errors was Chauvenet's criterion. When checking the data with this criterion, one error on the right was detected. No outliers were found on the left. According to the generalized results, namely, the vote on the three most statistical criteria, it can be concluded that the variational series belongs to the same general totality. Criteria presented in the article can be applied for the analysis of any data and for making conclusions based on them, if errors were found in the sampling.

Statistical methods for the analysis of pathological conditions population

An algorithm for calculating statistical indicators variational series interpulse distances for the three age groups of women of the indigenous population of Ugra. Dynamics of changes in the parameters of cardio indicates a significant decrease in the variance σx, which automatically decreases the yield values for the pulse interval of 10 sigma values for the older age group of women - Khanty.

Locally adaptive bilateral clustering for universal image denoising

This paper presents a novel and efficient locally adaptive denoising method based on clustering of pixels into regions of similar geometric and radiometric structures. Clustering is performed by adaptively segmenting pixels in the local kernel based on their augmented variational series. Then, noise pixels are restored by selectively considering the radiometric and spatial properties of every pixel in the formed clusters. The proposed method is exceedingly robust in conveying reliable local structural information even in the presence of noise. As a result, the proposed method substantially outperforms other state-of-the-art methods in terms of image restoration and computational cost. We support our claims with ample simulated and real data experiments. The relatively fast runtime from extensive simulations also suggests that the proposed method is suitable for a variety of image-based products — either embedded in image capturing devices or applied as image enhancement software.