Implementation of the optimal construction of a combination device and evaluation of reliability by output voltage

The theoretical propositions of the algebra of logic are considered. It is noted that the current microcircuitry based on the algebra of logic contains logical statements: true (yes) is a logical unit, false (no) is a logical zero. Based on the given logical function: ((ABC)×D + A×(BCD) + A×(BC)×D + (AB)×(CD), frontal, minimal, transformed minimal variants of the combination device are implemented, as well as minimized variants in the bases "AND-NOT" and "OR-NOT". A combination device based on import-substituting chips of 155, 176 series has been designed. The analysis of the obtained devices is made from the standpoint of technical and economic indicators, in particular, an assessment of the number of logic elements used, an assessment of the symmetry of the structure, as a result, a reduction in energy consumption, an increase in performance, improvements in parameters for reliability of functioning, a decrease in weight and size characteristics. Assuming that the law of change of the information parameter U1 is close to linear, taking into account the effect of temperature as boundary values for the elements of the applied microcircuits, taking the values -60 °C and +120°. Accordingly, the parametric reliability of the optimal implementation of the device according to the output voltage parameter is calculated. The conclusion is made about the inverse dependence of parametric reliability on temperature growth. A recommendation is given when evaluating parametric reliability for a number of other information parameters about the need to take into account both the number of chips used and the type of their interconnections.

The reliability evaluation of the water surface remote monitoring satellite equipment

The work is devoted to the reliability and effectiveness of the water surface remote monitoring space system. Analysis of existing monitoring methods has shown a high potential for using nanosatellites to solve the problem. As an object of study, 3U CubeSat was chosen with a payload placed on board in the form of a hyperspectral camera. To assess the reliability of the system, a mathematical model on the failure rates of subsystems is proposed. The structural and parametric reliability of the object was investigated in the Windchill Risk and Reliability software complex, taking into account the cyclogram of work and the specifics of the degradation process of individual components due to the influence of an aggressive space environment. To assess the effectiveness of the nanosatellite application, the dependence of the accuracy of determining water pollution on the operability of the photodetector was analyzed, since the photodetector is the central link in the transmission of optical information. The effective measurement of brightness spectral coefficients over the entire service life of nanosatellite is also obtained. Minimum required number of operable pixels was identified for monitoring the water surface with sufficient accuracy and reliability.

METHODOLOGICAL FOUNDATIONS OF DIAGNOSTICS OF METALWORKING TECHNOLOGICAL SYSTEMS ACCORDING TO PARAMETRIC RELIABILITY OF ENSURING A GIVEN QUALITY OF THE TREATED SURFACES

The paper presents the results of research justifying the need for diagnostics of metalworking technological systems on the reliability of ensuring the quality parameters of the surfaces of machine parts during machining. The fundamentals of the methodology of its implementation have been developed. Theoretical models of forming the quality parameters of parts surfaces during machining are considered and refined. This characterizes the scientific novelty of the results obtained. Circuitries for the construction of experimental control systems when conducting bench tests of machined surfaces of parts in conditions close to operational are of practical value. Circuitries are developed and computerized systems based on them for measuring the quality parameters of machined parts surfaces, including the working area of the technological system, are implemented. Recommendations on the rational choice of technological systems and the use of simulation methods in the study of parametric reliability of technological systems are presented. Mathematical and software analysis and processing of experimental results are developed and tested. These results will serve as a foundation for further development of research in the field of parametric reliability of technological systems, improving the quality of domestic engineering products and increasing their competitiveness at the world market.

Stochastic models for ensuring parametric reliability of the construction machines

The solution of technical problems to ensure the working capacity is largely determined by the effectiveness of theoretical and applied developments in an area of estimation and prediction of their reliability indicators. An effective approach to the analysis of failures and the development of operability and parametric reliability models provides an opportunity to obtain more adequate models of reliability of hydraulic drives of machines, as they more fully take into account the specifics of the structure and functioning of the hydro drive elements of construction machines, their relationships and features of the formation of parameters failures. And this will allow to get more real and accurate results of estimation of reliability indicators of hydraulic drives of both construction and other hydraulic machines. They do not exhaust all possible variants of models that can take place when analyzing the reliability of hydraulic drives of machines, but at the same time they to a certain extent extend and refine the set of known reliability models. Specific in terms of formation of parametrical failures are such consistently connected in terms of the layout of hydraulic elements, as working sections of hydraulic distributors and hydraulic cylinders, which are part of the subsystems of GPs and form the so-called functional areas (FA). Reaching the FA limit is a compatible result of the combined random process of evolution of the volumetric efficiency JCUA these elements, and the technical condition of the FA is estimated to be generalized by the JCUA, which equals the product of the JCUA of consecutively connected elements: . In this case, the probability of maintaining the capacity of the FA will be: . The processing of diagnostic information and the study of the reliability of GPs in real conditions of their operation showed that the distribution of JCUD hydraulic elements with a sufficient degree of consistency can be described under several theoretical laws. It is considered when the JCUA sections of the hydraulic distributor and hydraulic cylinder are distributed by gamma distribution and exponential distribution. The use of the general methodological approach to the analysis of failures and the construction of models of operability and parametric reliability provides an opportunity to obtain more adequate models of reliability of hydraulic drives of machines, as they more fully take into account the specifics of the structure and functioning of the hydraulic drive elements, They don't exhaust all possible models that can take place when analyzing the reliability of hydraulic drives, but at the same time they are to some extent expanding and refining the range of already known models of reliability.

DETERMINATION OF VIBRATION POWER OF VIBRATION SOURCES OF SPINDLE UNITS OF METAL CUTTING MACHINES

Monitoring the state of spindle assemblies of modern metal-cutting machines using CIP methods implies the possibility of installing control sensors in places with maximum vibration information content. In this regard, the assessment of the informativeness of the vibration field of the spindle assembly, which can be carried out in advance, taking into account the design features, geometric and dimensional characteristics, is an urgent task. Based on the energy approach, using the example of the spindle assembly of a universal lathe, a computational model is proposed, built along the median planes of the walls. On the basis of the calculated model, the equations of the energy balance were compiled taking into account the conditions for the transfer of vibration power between the walls of the housing. The method for determining the vibration power of the main sources in the spindle assemblies is given: a spindle with residual unbalance, a drive gear and bearings. It has been established that the most significant factors determining the vibration power introduced into the spindle unit housing are the operation of the bearings, the weight of the spindle and the location of its center of mass. The result obtained makes it possible to detect incipient defects in the bearings, which, as practice shows, are the defining elements of the parametric reliability of spindle assemblies. The resulting model of the vibration field can be used to determine the reference values of vibration velocities that are formed from sources in the absence of defects.

Identification of the conditions of a mine locomotive brake system as well as its functional and morphological model with the stressed closed kinematic circuit

The common tendency of mine rail haulage improvement is to increase axial power of electrical equipment traction, wagon capacity, and enhancing the speed of movement. In this context, it is typical for mine machine-building design to equip only locomotives with brake facilities. Thus, specific value of braking force of a train cannot exceed basic specific resistance to its movement. Test results of carriage rolling stock as for its braking efficiency as well as for its structural and dynamic analysis of braking mechanism have shown that a shoe-wheel brake of mine locomotives is not efficient under operation brake conditions in terms of the parametric reliability indices; hence, it is not applicable as an analogue for a trailing train part. The objective of the research is to determine a type of structural uncertainty while identifying brake conditions for adaptive control of alternative-structure tribologic system. Practical implication of the results is to determine both type and parameters of empiric dependence of brake shoe friction on a wheel tread upon the speed and braking as well as upon determination of kinetic characteristic of carriage rolling stock brake to be used in the theory of a mine train haulage to provide its safety.

Structural reliability and reliability sensitivity analysis of extremely rare failure events by combining sampling and surrogate model methods

The aim of this article is to study the reliability analysis, parametric reliability sensitivity analysis and global reliability sensitivity analysis of structures with extremely rare failure events. First, the global reliability sensitivity indices are restudied, and we show that the total effect index can also be interpreted as the effect of randomly copying each individual input variable on the failure surface. Second, a new method, denoted as Active learning Kriging Markov Chain Monte Carlo (AK-MCMC), is developed for adaptively approximating the failure surface with active learning Kriging surrogate model as well as dynamically updated Monte Carlo or Markov chain Monte Carlo populations. Third, the AK-MCMC procedure combined with the quasi-optimal importance sampling procedure is extended for estimating the failure probability and the parametric reliability sensitivity and global reliability sensitivity indices. For estimating the global reliability sensitivity indices, two new importance sampling estimators are derived. The AK-MCMC procedure can be regarded as a combination of the classical Monte Carlo Simulation (AK-MCS) and subset simulation procedures, but it is much more effective when applied to extremely rare failure events. Results of test examples show that the proposed method can accurately and robustly estimate the extremely small failure probability (e.g. 1e–9) as well as the related parametric reliability sensitivity and global reliability sensitivity indices with several dozens of function calls.