Level Of Operational Reliability Research Articles

Demonstration of a novel majority logic in a memristive crossbar array for in-memory parallel computing.

A memristive crossbar array can execute Boolean logic operations directly within the memory, which is highly noteworthy as it addresses the data bottleneck issue in traditional von Neumann computing. Although its potential has been widely demonstrated, achieving practical levels of operational reliability and computational efficiency remains a challenge. Here, we introduce a three-input majority logic gate supported by near-memory operations, serving as a universal gate and achieving both robust reliability and high efficiency in versatile logic operations. We fabricated a highly reliable HfOx-based memristive array, incorporating a series resistor to increase the reset voltage of the memristor, thereby increasing the operational voltage margin of the gate operation. This ensured reliable operation of the majority gate, resulting in successful experimental proof of combined 1-bit full adder and subtractor operations performed in 5 steps using 7 cells. Additionally, we propose that an N-bit parallel prefix adder (PPA) operation is possible in O(log2 N) steps, by taking advantage of the parallel operation capability of the majority gate. This achieves 8.5× higher spatiotemporal efficiency than the previously reported NOR-based logic system in 64-bit adder operation. Moreover, as N increases, the spatiotemporal efficiency further improves, which significantly enhances the applicability of memristive logic-in-memory.

Методика розрахунку основних характеристик підшипників ковзання систем і агрегатів автомобілів та аналізу їх трибологічної ефективності

A methodology for calculating the main characteristics of sliding bearings of car systems and units is proposed. The specified methodical approach is important when evaluating indicators of tribological efficiency of couplings of parts, nodes, systems and aggregates and operational reliability of cars as a whole. The bearing activation model makes it possible to formulate measures to increase the tribological efficiency of the couplings of parts and the level of operational reliability of nodes, systems and aggregates, and cars as a whole. In addition, the parameters of the actuation model also respond to friction modes. It is shown that it is possible to increase the tribological efficiency of the sliding bearing by means of design, technological and operational methods. The main formulas that make it possible to develop algorithms for calculating a set of bearing characteristics are presented: contact pressure, stress, strength, sliding resistance, wear, resource. For this purpose, the following values are used: compliance coefficients and relative load, contact angle, contact pressures, contact displacements, and the stress state in the contact zone. The geometric and power parameters of the bearing are involved in the developed methodology and algorithm. Modes of friction and the nature and magnitude of the load on the bearing are also taken into account. An algorithm for calculating auxiliary and main characteristics of a sliding bearing has been developed. The conditions of continuity and equilibrium in contact are clarified. The differential-integral equation of the operation of the bearing is obtained and the dependence of the current contact angle on the friction path and other parameters of the sliding bearing operation model is obtained. It is shown that the tribological efficiency of sliding bearings is established by the method of comparative analysis of tribotechnical characteristics determined by the results of tests on friction machines and a stand.

Studiul asupra sistemului fiabil pentru întreprinderile specializate în uscarea semințelor

This paper presents the results of a study conducted on a highly reliable system for agricultural enterprises specialised in drying seeds. The proposed system is an electrical system with a high level of operational reliability and has been designed to carry out research on the identification of solutions for significantly increasing the efficiency of the drying process of various agricultural plant seeds using the suspended layer treatment method. The main results of the study on the use of the system proposed by the authors, both in laboratory and in real conditions in specialized enterprises, highlighted an essential increase of the operational reliability, energy efficiency, process quality, and productivity, as well as cost reduction.

Operational Reliability Assessment of Distribution Network With Energy Storage Systems

In this article, a novel approach that considers the time-varying load restoration capability is proposed for operational reliability assessment of distribution networks. To evaluate the operational reliability, two indices are firstly defined as the minimal load loss under the worst-case fault contingency in the upcoming time interval. To search for the optimal remedial actions for load restoration, a sequential network reconfiguration (NR) model is then proposed considering the reconfigurability of feeders and capability of emergent power support of energy storage systems (ESSs). Since this model is a complex nonlinear mixed integer programming model, an improved greedy searching-based algorithm is proposed to compute the optimal remedial actions and to further evaluate the risk of load loss. Comparative case studies are presented in this article to demonstrate that the load level, the expectation of the state-of-charge of ESS and the failure duration have the impacts on the system operational reliability. Besides, the proposed sequential NR model can be used to enhance the reliability of distribution networks by enabling an effective sequential load transfer strategy under emergent conditions. Unlike traditional reliability assessment, the proposed method provides the operators with the real-time awareness of the operational reliability level considering the real-time condition of distributed resource equipped feeders and worst-case emergency constraints.

Управление техническим обслуживанием сельскохозяйственной техники в условиях автоматизации и цифровизации производства

When organizing maintenance activities for domestic agricultural machinery, paper workflow continues to dominate, which negatively affects the performance indicators and the level of operational reliability of machines. The engineering services of domestic agricultural enterprises remain beyond automation and digitalization in matters of managing the technical service of machines. The low adaptation of existing software products to the specifics of domestic agricultural production prevents the adoption of automated CMMS and EAM systems used in other sectors to manage the reliability of equipment in operation. The authors developed software with a set of functions similar to the functionality of well-known CMMS systems. The software includes Agrokompleks ASUTO in combination with the previously developed Agrokompleks Resursy warehouse management software and Agrokompleks MTP fuel management software. The automated system data model is adapted to the needs of engineering workers responsible for the performance of agricultural machinery. A practical test of the system was carried out at an agricultural enterprise with a fleet of 25 tractors. The results obtained confirm the hypothesis that the automation of engineering activities contributes to an increase in the operational reliability of agricultural machinery and a decrease in the labor intensity of managing service processes. The use of the automated system resulted in a decrease in the time spent on maintenance management by 35 to 38%, the probability of tractors having operational failure - by 26%. At the same time, the probability of tractors being in working condition increased by 1.8%. The research could be useful for the developers of EAM systems for the maintenance and repair management of agricultural machinery.

ОЦІНКА НАПРУЖЕНО-ДЕФОРМОВАНОГО СТАНУ ГЕОМЕХАНІЧНОЇ СИСТЕМИ «ЛАВА-ПІДРОБЛЮВАЛЬНА ВИРОБКА» ДЛЯ ГІРНИЧО-ГЕОЛОГІЧНИХ УМОВ ШАХТИ «КРАСНОЛИМАНСЬКА»

Purpose. Justification in the mining-geological and mining-technical conditions of the Krasnolimanskaya mine of the possibility of mining safety pillars of coal at horizons located below the capital crosscuts, while maintaining the stability of the capital workings. The possibility of such mining of coal pillars provides additional reserves of scarce coal for the needs of the metallurgical industry and thermal power industry of Ukraine. Methodology. The studies were done out using the capabilities of the Ansys software product based on developed geomechanical elastic-plastic models, developed taking into account the geological and mining-technical features of the Krasnolimanskaya mine deposit, during the phased development of safety coal pillars. At each stage of development of safety pillars, the preliminary stress-strain state of the coal rock mass around the crosscuts was recorded, the boundary conditions were changed, and changes in the parameters of the stress and deformation field were assessed. Ten stages of evolutionary changes allow us to assess the level of operational reliability of the crosscut. Results. As a result of the research, patterns of changes in the stress-strain state of the carbon rock mass around the capital crosscuts were obtained. Based on the analysis, the possibility of their safe operation was proven and the conditions for testing safety coal pillars were justified. Scientific novelty. For the first time, for the mining and geological conditions of the Krasnolimanskaya mine, the patterns of evolution of the stress-strain state of the coal rock mass around capital crosscuts during the gradual development of underlying safety coal pillars have been studied. Practical significance. The geometric parameters of the location of workings within the field of the Krasnolimanskaya mine are substantiated, in which the mining of coal pillars on the underlying horizons is safe and preserves the operational capabilities of capital crosscuts.

Study on the level of operational reliability of diesel engines for backhoe loaders

In the present study the main numerical characteristics of the reliability indicators for the Komatsu SAA4D104E-1 engines of the KOMATSU WB93R-5 backhoe loader have been determined, and the laws of resource allocation have been established. To study the level of reliability of machines, a methodology for experimental research has been developed, where the complex, comparative and formal methods, as well as the systematic, cybernetic and statistical approach have been used. It has been found that increasing the level of reliability of the engine elements can be improved by increasing the quality and timeliness of the repair and maintenance activities and compliance with the rules of operation. This study is a continuation of a study conducted by the author.

On the possibility of preventive assessments of damage rate of electrical networks (on the example of PJSC Rosseti Lenenergo)

The article is a continuation of the study of operational reliability level of electric networks (EN) of PJSC Rosseti Lenenergo in 2014 – 2021. The classification of causes of damage in the EN and identification of predominant among them in the Company's EN during the operation period are considered in detail. The purpose of the article is defined as the study of cause-and-effect relationships that determine the accident rate, for which a number of tasks are formulated to be considered. The input data are the results of annual reports on the number of failures, broken down by months from 2014 to 2021 in the Leningrad region (LO) and St. Petersburg (SP) electrical networks. As research methods, numerical methods for evaluating the study results and the MATLAB graphic editor technology were used to visualize the analysis results of the studied indicators. Methods of mathematical statistics and artificial neural networks were used as preventive damage assessment methods.To approximate the series of emergency outages, programming algorithms developed by the authors were used, which enabled the visualization of the studied characteristics. It is established that the most appropriate solution is to use statistical methods based on the least squares method. With their application, it is possible to study trend-seasonal models that allow to assess the influence of the seasonal component on the number of failures of electric grid elements.As a result of the study, the main causes of failures of elements of electrical networks have been identified. For the networks of the LO, the main damage cause is the fall of trees (41%), for the SP networks — the impact of unauthorized persons and organizations (48%). Trend and trend-seasonal models have been constructed that allow obtaining short-term forecasts of emergency outages. At the same time, the assessment of the seasonal component reflects the dependence of the number of accidents on the month in which they occurred. For a more detailed analysis, it is planned to consider the influence of climatic parameters on the studied indicator.

Системно-спрямований підхід підвищення експлуатаційної надійності транспортних машин на етапах їх життєвого циклу

The paper, based on a system-oriented approach, identifies how to increase the level of their operational reliability at the stages of the life cycle of transport machines operating in open pits and in the conditions of agro-industrial production. At the start-up stage of power units, a method of reducing the wear of parts is proposed. The scheme of realization of a way is developed. It is determined that it is effective to use this method when operating vehicles in harsh non-stationary conditions and "start-stop" modes. It is experimentally proven that the proposed method allows to save up to 15% of consumables and increase the life of the engine oil. The study of the effectiveness of the use of additives NIOD-5, RoilGold and the proposed additive KGMT-1 to motor oil was carried out at the stage of bench tests of power units of transport vehicles. It has been determined that the addition of a composite additive to the engine oil provides a steady increase in power, torque and reduction of specific fuel consumption. RoilGold and KGMT-1 additives work especially effectively. At the stage of operation of transport vehicles in open quarries and conditions of agro-industrial production, research proved the extension of the use of motor and transmission oil by 25 ... 40%, revealed a decrease in maintenance and the need to adjust the maintenance of vehicles. Based on the results of operational studies, a corrective table of terms of replacement of motor oil of transport vehicles operating in harsh non-stationary conditions is constructed. It is found out how to ensure the proper level of operational reliability of transport vehicles.

Елементно-модульний метод системи технічного сервісу транспортних машин

The paper proposes that the element-modular method of the system of technical service of transport machines is based on the characteristic intervals of change of diagnostic parameters that determine the technical condition of their components, systems and units as elements. Theoretically substantiated changes in diagnostic parameters taking into account the degree of restoration of the technical condition of systems and units for technical service operations. The maximum resource of elements of the transport machine and the law of distribution of this indicator are considered. From the economic point of view the expediency of restoration of a technical condition of elements of transport cars by the offered system of technical service is proved. The criterion of economic expediency of application of technical actions on restoration of a technical condition of transport cars is offered. It is shown that according to this criterion it is possible to estimate the cost of technical actions to improve the technical condition of the transport vehicle and the fleet as a whole. The criterion of efficiency of technical action on improvement of a technical condition of an element of transport cars and a factor of rational use of a resource with possible situations is offered also. An algorithm for controlling the system of technical service of transport machines by the element-modular method has been developed. The results of forecasting technical control and regulation of the studied elements of transport vehicles: engine and transmission are considered. It is shown that the proposed element-modular method of technical service makes it possible to adjust certain technical operations to ensure and restore the appropriate level of operational reliability of transport vehicles.

Analysis of the Negative Daily Temperatures Influence on the Failure Rate of the Water Supply Network

As a part of the critical infrastructure, water supply systems must be characterized by an appropriate level of operational reliability and safety. One of the threats to this is the failure of the water supply network, influenced by many factors, among which we can distinguish internal factors related to the process of designing, construction and system operation, and external factors related to the impact of the environment. The paper presents the influence of negative daily temperature on the failure rate of the water supply network, taking into account the material of the pipes, their diameters, and the cause of failure. The research was carried out on operational data from the period 2004–2018 from the water supply network in a city located in south-eastern Poland. The relationship between the daily temperature and the failure rate of the water supply system has been shown. As the temperature values drop, the failure rate values increase. The biggest influence of the negative daily temperature on the water supply network failure rate is observed for cast iron pipes. PE and PVC pipes are more resistant to the influence of negative temperatures. The most common cause of failure is corrosion and unsealing of the pipes. Pipes with the diameters of 100, 150, 300, 350, and 400 mm in distribution and main networks turned out to fail most often. These results can be used by water supply companies to limit the influence of factors related to negative daily temperatures on the failure rate of the water supply network.

Determination of Operational Reliability of Firefighting Special Vehicles

In this paper, an analysis of the reliability and availability of special vehicles has been performed. An analysis of operational data performed using the tools of mathematical theory of reliability has been realized. The analysis was performed for four specific types of firefighting vehicles, which are operated as part of preventive and immediate firefighting activities. The achieved level of operational reliability, maintainability and availability of heavy vehicles has been determined. Subsequently, a mutual comparison of the reliability of these types of vehicles was described.

Modern systems for monitoring the stress-strain state of hazardous power generating facilities

The paper considers the issue of effectively increasing the level of operational reliability of power generating nuclear and hydraulic facilities. Over the past 20 years, the number of accidents at these facilities has been growing. There are many factors affecting the collapse of structures, but, according to the authors, the lack of a monitoring system capable of fully assessing not only the stress-strain state, but also the so- called “residual” stresses of the material is the dominant direction of research. The same question is raised at the state level, as evidenced by the requirements of the STO, GOST and Federal laws, to which the authors refer below. The legislative prerequisites (requirements) for the creation of an improved system for monitoring critical structures, corresponding to the development trends of the construction industry, as well as the modernization of the existing fund are listed. The drawbacks and advantages of existing monitoring systems (strain gauge, string, fiber-optic sensors and acoustic emission systems) are analyzed in detail, and the general lack of the possibility of measuring, evaluating "residual" stresses in the material of structures is noted. A fundamentally new system for monitoring the stress-strain state of building structures and power equipment is proposed, which is based on the Foerster effect, a comparison is made with the existing systems described above. The main features and capabilities of the method are noted and options for use at highly important facilities are proposed.

Design and Integration of a Dual Redundancy Air Data System for Unmanned Air Vehicles

Air data systems measure airspeed, pressure altitude, angle of attack and angle of sideslip. These measurements are essential for operating flight control laws to ensure safe flights. Since the loss or corruption of air data measurements is considered as catastrophic, a high level of operational reliability needs to be achieved for air data systems. In the case of unmanned air vehicles, failure of any of air data sensors is more critical due to the absence of onboard pilot decision aid. This paper presents design of a dual redundancy air data system and the integration process for an unmanned air vehicle. The proposed dual-redundant architecture is based on two independent air data probes and redundancy management by central processing in two independent flight control computers. Starting from unit testing of single air data sensor, details are provided of system level tests used to meet overall requirements. Test results from system integration demonstrate the efficiency of the proposed process. Keywords: ëŒ€ê¸°ìžë£Œì‹œìŠ¤í œ, 이중화설계, 체계통합, ëŒ€ê¸°ìžë£Œë³´ì • Keywords: Air Data System, Dual Redundancy Design, System Integration, Air Data Calibration

Grapho-analytical studies of deformation in deformed thin-walled contours

Increasing the levels of operational reliability of technical means of modern production involves, in particular, the optimization of the deformation parameters of individual components of these tools. The main deformation-operational feature of such structures as elastic shells of the pneumatic periphery of mobile vehicles, and individual links of long-link cargo chains is a stochastic change of their shape in contact with the deformed environment. The basis for the optimization of the operational reliability of deformed thin-walled circuits of such structures under power load is to determine the ratios of their geometric parameters, in which the process of deformation under load does not transform their initial shape from “folded” (out-of-bounds) state to “foldless” state toroidal surfaces, which should be described using the Cassini family of ovals. Based on the established regularities of changing the configuration of the meridian of soft elastic shell and flat closed structures, which are deformed by external loads, three main conditions of using model typical contours of Cassini ovals as graph-analytical models of elastic shells of pneumatic mobile periphery chains. These conditions of graph-analytical modelling include: closedness and continuity of the curvature of the toroidal surface; generalization of the initial shape of the surfaces of toroidal contours; reduction of variable geometric shapes of contours to a single generalized equation. The results of the given grapho-analytical researches allow to define design structural and geometrical parameters of tires of engines of mobile means and separate links of cargo chains with the increased operational indicators of reliability of their work.

ON DEVELOPMENT OF AVIATION EQUIPMENT’SRELIABILITY MODELS (ON THE EXAMPLE OF HELICOPTERS)

On the example of helicopters, the topical issues of systematization and mathematical processing of statistical information taking from fault log sheetsto assess the level of reliability and flight safety of state aviation equipment are considered.
 The reliability of all helicopter systems must meet the pressing needs of defense capabilities and support the capabilities of the state aviation of Ukraine to carry out combat missions at the current level. Improving preparedness for assigned tasks will facilitate participation in combined operations with peacekeeping and NATO forces. The considered model of the system of aviation equipment on the example of helicopters consists of interdependent, jointly functioning, united by a single purpose of five subsystems of the corresponding type of specialty: “helicopter and engine”, “aircraft armament”,“aircraftequipment”, “avionics equipment”,“navigation and target acquisition system”.
 Realization and methodical approaches to the development of complex failuremodels of the elements of “helicopter and engine” system by types of helicopters are substantiated. The paper proposes to address on the example of helicopters the lines of approach the problem of assessing the real level of operational reliability and flight safety of aircraft to maintain their serviceable condition.
 When putting military aviation assets into operation according to the technical condition, using statistical models of reliability and flight safety, the important task of increasing resource indicators is solved, which requires improving the system of collecting, processing and analyzing information from fault log sheets.

DETERMINATION OF THE TREND OF CHANGES OF RELIABILITY INDICATORS OF STATE AVIATION HELICOPTERS ACCORDING TO OPERATING DATA

The most important characteristics of the processes efficiency in aircraft equipment technical operation are the operational reliability characteristics. High reliability of aviation equipment is the main condition for its readiness, efficiency and safety.
 The aircraft equipment reliability is its ability to perform specified functions, maintaining during some time the values of the established flight and technical and operational indicators within the specified limits, which correspond to the specified modes and conditions of use, maintenance, repair, storage and transportation.
 Despite the quick scientific and technological progress in aviation, the problem of flights safety has become extremely acute in the present time. Empirical data statistical processing is an urgent task in monitoring of the Ukrainian Armed Forces aircrafts operation and determining trends in maintenance and repair, areas of modernization of armaments and military equipment.
 The subject of the work is the analysis and system approach based on the developed estimation technique of aviation equipment reliability indicators. The results of determined helicopters and their functional systems reliability are presented. The trend and the main reasons for the change in reliability indicators for 2016-2019 are determined.
 The main purpose of reliability analysis is to determine the causal relationships between quantitative and qualitative reliability indicators and the level of flight safety that lead to aviation accidents.
 Statistical information in the form of fault records and reports, where the generalized operational data are sent by the State aviation units according to the methodical recommendations.
 Indicators analysis of operational reliability and flights safety for helicopters according to statistical data of failures, damages and incidents is done. Moreover, the trend and the main reasons for the helicopters reliability indicators changes for the period 2016-2019 are defined.
 The results of research are presented in the final tables, which show the average values of operational reliability, flight safety and the level of combat flight task for different types of helicopters in all specialties.
 The causes of malfunctions that affect the level of operational reliability, flight safety and non-fulfillment of the flight task on helicopters for the period 2015-2019 were taken into account.
 According to the statistics analysis of the malfunctions reported causes , it is determined that the total number of reported malfunctions on different types of helicopters in 2019 increased by 11.0% compared to 2018, compared to 2017 by 43.7%, compared to 2016 by 58.4%, compared to 2015 by 70.0%.

Management of structure formation and properties of aluminum plastic deformed welded joints with low specific weight

ABSTRACT Investigated the influence of casting technological parameters on the formation of structure and properties of cast from VAL19 alloy as well as the welded joints of casting and deformable aluminium alloys (VAL19 + 1420) that provide the necessary level of operational reliability of aircraft equipment.

Increasing the operational reliability of tractors by backing up the replacement elements

The article deals with the issues of choosing a redundancy method and the frequency of replacing tractor elements while ensuring the level of operational reliability in agricultural enterprises. It is noted that the operability of the system is ensured as long as there are reserve elements available to replace the failed main elements (and there is a possibility of switching the reserve elements into an operational state). One of the general methods for solving this problem is a method based on the use of Markov processes. In this case, the process of changing the states of the tractor is presented as a dynamic system, the state of which changes discretely in continuous time in a random manner.

АНАЛІЗ МЕТОДИЧНИХ ПІДХОДІВ ДО ОЦІНЮВАННЯ НАДІЙНОСТІ АВІАЦІЙНОЇ ТЕХНІКИ ДЕРЖАВНОЇ АВІАЦІЇ ЗА ЕКСПЛУАТАЦІЙНИМИ ДАНИМИ

Розглянуто методичні підходи, що пропонуються для оцінювання надійності авіаційної техніки за експлуатаційними даними. Представлено результати оцінювання показників надійності вертольотів та їх функціональних систем за експериментальною методикою. Запропоновано напрями подальших досліджень з метою удосконалення даною методикою оцінювання надійності та підвищення безпеки польотів при переведенні військової авіаційної техніки на експлуатацію за технічним станом.