FEATURES OF STRENGTH TESTING OF PASSENGER WAGON AUTOMATIC REGULATORS

The automatic regulator РКЗТ-675 (РТПР-675) and РТПР-675M is installed in the brake lever transmission of the passenger car and used for automatical maintenance of gaps between the surfaces of rolling of wheel pairs and brake pads within the established limits irrespective of the wear of the rolling surfaces of wheels. The design of auto regulators allows you to change the stroke of the piston rod and the brake cylinder and to manually release and tighten the regulator. Scope of auto regulators: freight, passenger cars and electric trains of the main railways. The article is devoted to solving the problem of contradictions in clause 15.5.7 of the current departmental Ukrainian instruction ЦЛ-0013 for repairing brake equipment of the railway carriage of the existing requirement for mandatory compliance with screw unscrewing in size "a" within 300-350 mm when testing automatic regulators on an automatic test stand for strength under load a normalized force of 8t in the longitudinal direction, provided that there are no residual deformations of the automatic regulator screw along its length. The article aims to refute the dependence of the values of the stress state of an automatic regulator when testing its strength on a test bench from a change in its length in the entire possible range of screw unscrewing by size "a" in the allowable range of 0-600 mm. The problem is solved by calculation using two different methods, and the results of the stress state values of the automatic regulator with different lengths of screw unscrewing by size “a” are compared with each other. Based on this, the general conclusion is made that the size “a” (within the range of 0–600 mm) of the automatic regulator screw unscrewing when testing it for strength with the same load force (N = 8t ≈ 80 кН) in the longitudinal direction does not affect the calculated value of the screw tension σ = 113.23 MPa when tested on an automatic bench. The developers of the departmental Ukrainian instruction ЦЛ-0013 are invited to make in clause 15.5.7 corresponding changes regarding the requirement of optional observance of the value of the size "a" within 300-350 mm at the bench test of the automatic regulators for the tensile load under the standardized force of 8t.

FEATURES OF TESTING OF THE BUILT-IN SOFTWARE OF MEASURING INSTRUMENTS

Protection against unauthorized modification or its components, measurement data and protection against external unintentional and accidental interference are particularly important for measuring instruments (MIs) software. The possibilities of ensuring the security of built-in MI software, as well as MI as a whole, are considered. The analysis of the main features of built-in MI software on the basis of documents, guidelines and recommendations of international and regional organizations in the field of legal metrology are shown. The characteristics of MI software in accordance with international and regional documents, guidelines and recommendations are the establishment and regulation of such tests, which must be provided in the testing methods for specific MI with embedded software.

ORGANIZATIONAL AND INFORMATION DESIGN OF TECHNICAL HIGHER EDUCATION INSTITUTIONS

The educational services provided to applicants for higher education in accordance with the Law of Ukraine on Education and the Law of Ukraine on Higher Education are analyzed in the article. The provision of educational services as a separate type of commercial activity, where the leading role is played by the quality of educational services as a key point of competitiveness is defined. The general approach and a kind of organizational design of institutions of higher education which corresponds to the necessary commercial character of their activity is offered; the content and structure of organizational and information design of technical institutions of higher education are determined; the role of each structure in the coordination of the functioning of higher education institutions and the differences in the coordination mechanisms used by them (information links) are analyzed; it is shown that one of the differences in terms of organizational design of technical institutions of higher education from ordinary commercial organizations is the presence of legally defined collegial and advisory authorities at all hierarchical levels of the organizational structure; it is proposed on the basis of these authorities to create a new coordination mechanism that allows the transformation of existing information links into a single information flow of decision-making, thus eliminating contradictions in their approaches, which will coordinate the activities of all departments to maximize the achievement of expected learning outcomes. The general structure of organizational design of technical institution of higher education and the simplified example (variant) of the coordination mechanism of activity of the specified structures are given. Further development of the proposed approach to the organizational design of institution of higher education is the study of the quality of processes that provide coordination mechanisms (information links) and the development of methods for estimating their quality and quality of educational services.

SIMULATION OF ASYMMETRICALLY DISTRIBUTED PROCESSES

The article deals with the problems of modeling asymmetrically distributed stochastic processes and assessing the quality of the modeling process based on the use of the Pearson chi-square criterion. The problems that arise in each individual case of modeling are identified. As a method of generating an output stream of random numbers distributed according to a given law of probability distribution, the method of inverse functions is proposed, and as a generator of the input stream, it is proposed to use a stream generated by the Mersenne generator. The analysis of research methods and evaluation of computer models of stochastic processes is given and the choice of a nonparametric research method based on histograms is substantiated. Suggestions on the choice of their main parameters are provided: the size of the interval for separating the statistical set of values of the output stream of the model and the number of such intervals, calculated on the basis of the size of the statistical sample. It is shown that the quality of statistical material significantly affects the success of modeling. In the case of an asymmetric nature of the distribution of the model's output stream, the accuracy of calculating the chi-square exponent is significantly affected by those values that fall into the extreme intervals of the histogram. It is shown that the reason for this is the incommensurability of their values with the values in the central part of the histogram and this is a separate modeling problem, as a solution to which there can be filtering of the statistical set, preceding the determination of the quality indicator. The sequence of procedures for forming a model of a stochastic process and processing the results of calculating the parameters of the histogram is determined.

ALTERNATIVE EVALUATION THE RESULTS OF KEY COMPARISONS OF NATIONAL STANDARDS

In the framework of the Agreement of International Committee on Weights and Measures on Mutual Recognition of national standards, calibration and measurement certificates issued by national metrology institutes (NMIs), key comparisons serve as the basis for establishing calibration and measurement capabilities of NMI with implemented quality management system. On this basis, the competence of a specific NMI to perform calibration of working standards and measuring instruments for the customer laboratories is determined. In order to attract as many NMIs as possible to participate in key comparisons of standards, Regional Metrology Organizations are widely involved in conducting such comparisons. The practical application of traditional evaluation the results of key standards comparisons and displaying them in the special database of key comparisons (KCDB) of International Bureau on Weights and Measures (BIPM) may be difficult for some NMIs and for national laboratories accredited by national accreditation bodies that wish to use NMI calibration services. This is due to the fact that the KCDB BIPM only displays the degree of equivalence of a NMI standard with corresponding expanded uncertainty without any other characteristics for evaluating calibration or measurement capabilities. The paper presents a proposed alternative evaluation of results of key comparisons of standards, which simplifies the analysis of calibration services by NMIs. It envisages the use as a criterion of consistency of the results obtained from the comparisons of the En index to analyze the degree of equivalence of the NMI standard and the corresponding extended uncertainty. The practical application of the evaluation for results of key comparisons of standards of electric power is considered. This contributes to a more streamlined calibration of work standards for specific established purposes for both NMIs and accredited laboratories.

PECULIARITIES OF BENCH TESTS OF HYDRAULIC DAMPER OF RAILWAY PASSENGER CAR

The studies are devoted to the scientific problem connected with the significant differences in the piston stroke values during testing of the same type of hydraulic damper by the use of different test benches and methods. The damper manufacturer uses the mechanical test bench ЛИИЖТ, the design of which was created back in Soviet times. This test bench has certain design limitations regarding the amplitude of harmonic vibrations of the drive mechanism, and therefore the dampers are tested at short piston strokes, which are 4 %; 8 %; 16 %, respectively, as a percentage of the maximum stroke of the piston. The passenger car depot, as a consumer of absorbers, conducts their tests at the more modern universal stand ИГK-90.1, which differs from the mechanical stand of the manufacturer of absorbers, both in design and in the method of testing absorbers. The purpose of the research is to confirm or deny the presence of influence of the value of the piston stroke on the expert assessment of the technical condition of the hydraulic damper. To solve this problem, the modern universal test bench ИГК-90.1 carried out experimental studies with different volumes of damping fluid in the slave cylinder of the КВЗ-ЛИИЖТ 45.30.045M type. A comparative analysis of the protocols showed that in the “compression” mode, the nature of the obtained dependences of the force and resistance parameters with an increase in the piston’s moving speed changes depending on the volume of the damping fluid in the damper’s working cylinder. The authors believe that testing the absorbers during the piston stroke of at least 80% of the maximum piston stroke allows the presence of deformations of the guide rod and the insufficient amount of damping fluid (the presence of air) in the absorber’s working cylinder. Deformation of the stem can lead to jamming in operation. The presence of air in the working cylinder of the damper is generally unacceptable since such damper is not able to absorb the vertical and horizontal vibrations of the car body in a curved section of the railway track with the height difference of the railheads 150 mm.

RESEARCH OF PROCESSES OF DEVELOPMENT OF INTERNATIONAL MANAGEMENT SYSTEMS STANDARDS

Today, management system standards are an integral part of the overall system of the enterprises control system and one of the effective methods to ensure the contentment of all stakeholders in various areas of activity. The development of management theory has allowed ISO to set up common management practices in form of international standards. Since international management system standards have implications for business practices at all levels and in all industries, research of processes and practice of their development is relevant. It was revealed that the international standardization of management systems occurs in three directions: the standardization of general management systems, their concretization in various industries, and the provisioning of the recommendations for their implementation. Currently, ISO has developed 93 standards for management systems in the field of construction, innovation, energy, food and agriculture, packaging, medicine, information technology, social responsibility, mechanical engineering, safety, environment, transport. At the same time, the need to develop each standard for the management system should be confirmed by a justification in terms of its market significance. Also, to stimulate international cooperation and the practical application of management systems, ISO has developed a structure, common text and terms that should contain management system standards prepared directly by ISO or by various stakeholders at the national or industry level. It is noted that the technical committee-developer of the standard may apply additional specification to ensure that the draft standard being developed does not deviate from its terms of reference and high-level structure. It is concluded that this approach will simplify the process of developing such standards, the procedure for voluntary confirmation of conformity, the introduction of several management system standards and the creation of an integrated management system at the enterprise, which is seen as a way to better manage it.