Developing the Model of Reliability of A Complex Technical System of Repeated Use with A Complex Operating Mode

Solving the problems of setting requirements to the reliability of complex technical systems for various purposes presupposes their classification according to the features characterizing the purpose, modes of use, etc. According to the modes of use, systems are divided into objects of continuous long-term use, repeated cyclic use, and single-use. The objects of repeated cyclic use include the systems operating in cycles. Durations of the periods of work and pause in the cycle are considered deterministic values. Technological and/or technical maintenance is carried out in pauses between the operation periods.In addition to the known classification, it was proposed to introduce a group of systems of repeated use with a complex operating mode. A complex mode is understood as a mode that includes waiting for a request of the system use and executing the request after it arrives at a random time.An analytical model of reliability of such a system has been developed in the form of a ratio for a non-stationary total coefficient of operational readiness. This model describes the processes of the system functioning in the intervals of waiting and use. In this case, the duration of the intervals of waiting and/or execution of the request are random values.Ratios for this indicator were obtained for three options of specifying the functions of distribution of durations of waiting in a turn-on condition and fulfilling the request for use.The developed model makes it possible to set requirements for reliability and maintainability of the systems with a complex operating mode.The results of modeling the dependences of the operational indicators of reliability on parameters of the functions of distribution of durations of waiting and executing the request were obtained for different distributions. Recommendations were formulated concerning the substantiation of the requirements to reliability and maintainability of the systems under consideratio

Development of an Estimation-experimental Method for Estimating the Preservation Indicators of Single-use Articles

To manage the operation of modern single-use products, it is necessary to evaluate their preservation indicators as uncontrolled, non-repairable, and maintenance-free objects. Data for assessing its parameters are considered as one-time censored samples with continuous monitoring, which does not correspond to the mode of storage of products during operation. Under the conditions of limited volumes of censored samples, it is problematic to identify the parametric model of persistence. To solve this problem, a non-parametric estimation-experimental method has been devised, which is a set of models for data generation, estimation of the function of the distribution of the preservation period and preservation indicators. The data generation model is represented by a scheme of operational tests and analytical relationships between the quantities of tested and failed articles. The model of estimating the distribution function describes the process of its construction on the generated data. Models for estimating preservation indicators are represented by ratios for their point and interval estimates, as functionals from the restored distribution function. Unlike the well-known ones, the developed method implements the assessment of indicators under the conditions of combined censorship. The method can be used to assess the preservation indicators of single-use articles with an error of at least 7 %. At the same time, their lower confidence limits are estimated at 0.9 with an error not worse than 14 % with a censorship degree of not more than 0.23. The restored distribution function agrees well (reliability 0.9, error 0.1) with the actual persistence of articles with censorship degrees of not more than 0.73, which is acceptable for solving the problems of managing their operation

Development of the Combined Method for Evaluating and Controlling the Reliability Indicator «Probability of Failure-free Switching» of A Radio Technical Complex

The operation of a radio-technical complex based on a technical condition is represented by cycles. Each cycle implies control over a limiting state in order to make timely and informed decisions on managing the operation of a radio-technical complex. That should resolve the task of assessing and monitoring the indicators of fault-free operation with the required accuracy and reliability based on operational observations and, if necessary, special tests that could minimize the cost of special tests. Given the introduction for a radio-technical complex of the repeated application of a new indicator of fault-free operation «the probability of trouble-free switching», a combined method of its evaluation and control has been developed. This method is a set of known and developed criteria, models, methods, and schemes that determines the sequence of their application for joint evaluation and control of this indicator. The criteria for verifying the uniformity of data on the operational observations and special tests for the fault-free operation of a radio-technical complex have been defined, as well as the corresponding models for assessing the one-sided lower confidence boundaries of the indicator under consideration, and the methods to control it. The devised method makes it possible to derive estimates of the probability of trouble-free switching, as well as the magnitudes of the observed risks of decisions being made with acceptable accuracy and reliability. The results of modeling the devised combined method helped obtain the accuracy and reliability of its estimates and the observed risks of controls carried out. Recommendations have been compiled for applying the method to address the challenges of joint assessment and control of the probability of trouble-free switching of the considered complexe

Development of the Combined Method for Evaluating and Controlling the Reliability Indicator «Probability of Failure-free Switching» of A Radio Technical Complex

The operation of a radio-technical complex based on a technical condition is represented by cycles. Each cycle implies control over a limiting state in order to make timely and informed decisions on managing the operation of a radio-technical complex. That should resolve the task of assessing and monitoring the indicators of fault-free operation with the required accuracy and reliability based on operational observations and, if necessary, special tests that could minimize the cost of special tests. Given the introduction for a radio-technical complex of the repeated application of a new indicator of fault-free operation «the probability of trouble-free switching», a combined method of its evaluation and control has been developed. This method is a set of known and developed criteria, models, methods, and schemes that determines the sequence of their application for joint evaluation and control of this indicator. The criteria for verifying the uniformity of data on the operational observations and special tests for the fault-free operation of a radio-technical complex have been defined, as well as the corresponding models for assessing the one-sided lower confidence boundaries of the indicator under consideration, and the methods to control it. The devised method makes it possible to derive estimates of the probability of trouble-free switching, as well as the magnitudes of the observed risks of decisions being made with acceptable accuracy and reliability. The results of modeling the devised combined method helped obtain the accuracy and reliability of its estimates and the observed risks of controls carried out. Recommendations have been compiled for applying the method to address the challenges of joint assessment and control of the probability of trouble-free switching of the considered complexe