Spare Elements Research Articles

SCIENTIFIC AND TECHNICAL APPROACHES TO BUILDING A SYSTEM OF DELIVERY OF MATERIAL AND TECHNICAL EQUIPMENT FOR THE NEEDS OF THE AIR FORCE UNITS OF THE ARMED FORCES OF UKRAINE WITH THE USE OF TRUCK UAV COMPLEXES

The possibility of using cargo unmanned aerial systems to solve the tasks of operational delivery of spare parts for weapons and military equipment, other material and technical means to units and separate units of the Air Force of the Armed Forces of Ukraine was considered. The analysis of modern developments of cargo unmanned aerial systems (unmanned aerial vehicles) of the leading countries of the world for military needs was carried out. The question of the formation of external accounting of unmanned aerial systems based on transport unmanned aerial vehicles has been voiced), scientific and technical approaches to the construction of a perspective system of providing material and technical means to military units and units of the Air Force of the Armed Forces of Ukraine using unmanned aerial means of cargo delivery have been proposed.
 The main advantage of using cargo unmanned aerial systems and devices as part of the supply system of material and technical means for the needs of air defense units is to increase the efficiency of solving the tasks of delivering, first of all, the necessary acutely scarce elements of spare parts that have a limited working life before failure. The timely replenishment of spare parts sets is an important task within the framework of their planned deliveries, but it becomes most relevant in the event of the need for emergency delivery of a spare element required during the current repair of the sample, but for some reason not included in the regular set.
 The specified scientific and technical approaches determine the possibilities of creating a promising system for the delivery of military cargo using specialized flying robotic systems based on transport (cargo) unmanned aerial vehicles, which allows solving the task of delivering military cargo with an economically justified method in various conditions of the operational and logistical situation, including and to individual units of the Air Force of the Armed Forces of Ukraine, which are located in hard- to-reach areas in case of possible destruction of road infrastructure facilities.

EVALUATION MODEL OF THE RECOVERY PROCESSES OF NON-MARKOVIAN SYSTEMS, CONSIDERING THE ELEMENTS UNRELIABILITY UNDER ARBITRARY DISTRIBUTION LAWS

The subject of the study is the reliability of recoverable non–Markovian systems, functioning of which is described by arbitrary distribution laws. The purpose of the article is to develop a mathematical model of the functioning of modern computer systems under arbitrary laws of the distribution of stay duration in each of the states, taking into account the recovery system and the provision of spare elements. The main task is to develop an adequate model of the system functioning process, taking into account the non-Markovian character of the processes occurring in the system, its possible large dimension, and the presence of a hierarchical recovery system. Based on this model, a method for calculating the density of the system recovery time distribution has been developed. At the same time, a universal four-parameter distribution is proposed to describe random processes occurring in the system. Using this approximation, the calculation of the desired parameter of the recovery flow is performed by solving the Volterra integral equation with a difference kernel.

ELECTRIC CYLINDER AS A PROMISING TYPE OF ELECTROMECHANICAL DRIVE OF THE MAIN DOUBLE-LEAF GATES OF SHIPPING LOCKS IN RUSSIA

The electric cylinder as a promising type of electromechanical drive for controlling the main miter gates is analyzed based on domestic and foreign experience. It is shown that, for a number of reasons, several different types of electric drives are in operation in Russia, differing from each other in kinematic schemes, operating parameters, dimensions and operational costs. Variety of electric drives types reduces their serviceability, requires the search for spare elements, the performance of repair work by third-party organizations, which, in turn, reduces the productivity of the gateway process. The operated electromechanical and electrohydraulic inputs of the main double-leaf miter gates of navigable locks with a chamber width of about 18 meters are analyzed. It is shown that the results of the drives comparison make it possible to clarify the calculations of the required power and load capacity, to contribute the development of a single regulatory document regulating the process of designing and selecting the operating parameters of an electric cylinder for specific operating conditions. The data compiled on the basis of foreign and domestic experience in the operation of different types of double-leaf miter gate drives, trends in their development, the reasons for their replacement with more modern drives are obtained. Special attention is paid to the disclosure of the reasons for replacing standard drives with an electric cylinder during the locks reconstruction. It is shown that the accurate calculation of the actually required performance indicators and the correct choice of the electric drive type, based on the conditions of future operation, lead to a noticeable increase in the life cycle of the shipping lock and its mechanisms.

Methodology to calculate the required number of spare parts in order to ensure the required operability of equipment parks

Comprehensive mechanization of work is accompanied by large expenditures for ensuring the serviceability and operability of the machines fleet. There is an almost constant need for spare elements (machines, units, parts) to maintain the required use level of machines and equipment, as well as to perform work on schedule. An algorithm of actions allowed finding a rational level of redundancy for machines and their parts under various operating conditions and constructive improvement of technology. The article showed that the rate of failure is influenced by the natural and climatic factor, the "age" of machines, and other conditions. Optimization of the companies’ repair policy in terms of ensuring the serviceability of equipment is a complex multi-vector problem. The described methodology makes it possible to determine the necessary range and volumes of spare elements for a known fleet of machines at a given load and under the conditions of ensuring the calculated level of reliability and serviceability of the equipment, maintenance, and repair. The application of the proposed method allows optimizing the cost of spare elements while ensuring the established level of reliable operation for machines and technological sets of equipment. Also, it becomes possible to obtain rational solutions for the formation of a warehouses network on different levels to meet the needs of firms with the dispersed operation of machines and mechanisms at a large number of objects.

Semi-Markov model of the functioning of redundant measuring instruments, taking into account the frequency of verification

The problem of modeling the process of functioning of redundant measuring instruments is considered. On the basis of the developed model, the determination of the frequency of verification of complex duplicated measuring instruments based on the semi-Markov model of the process of their functioning is justified. The relevance of the application of the theory of semi-Markov processes for modeling the functioning of redundant technical systems, including measuring instruments, is shown. A semi-Markov model of the process of functioning of measuring instruments has been developed, which allows us to take into account the influence of the frequency of verification, the provision of measuring instruments with spare elements, as well as the level of reliability and maintainability on the reliability of measuring instruments. A method is found for defining a semi-Markov process that correctly and adequately approximates the real process. The indicator of the effectiveness of the functioning of the measuring instruments and the corresponding model is the availability factor of the measuring instruments.

Розрахунок показників достатності комплектів ЗІП

To ensure high operational reliability of electronic equipment, maintenance and repair, and pro-long the service life of the equipment, there is proposed a system which comprises diagnostics and repair tools, sets of spare parts (so-called «ZIP»), including spare parts design to ensure re-liability criteria of the system, i.e., sufficiency, composition and the number of spare parts that are expected to ensure the operation of the system with the required reliability. The paper pro-poses to use the method of calculating spare parts on the basis of more adequate models of reli-ability which leads to more accurate forecasting of the required amount of spare elements and, as a result, to more efficient completeness of the equipment with spare parts. There have been determined the methods of replenishing which are used depending on the purpose of the equip-ment, the system of its maintenance and repair, the requirements for equipment reliability: whether it is periodic, or continuous, periodic replenishment with emergency deliveries or re-plenishment by level. To ensure high operational reliability of electronic equipment, mainte-nance and repair, and prolong the service life of the equipment, a support system is proposed, which includes diagnostic and repair tools, sets of spare parts, etc. The design of spare parts with compliance with the criteria of system operation reliability is considered. The task of re-quirements to the indicators of sufficiency of spare parts for products with non-renewable spare elements has been determined. The task of requirements to spare parts adequacy indicators for products with renewable spare parts has been distinguished as well. The article also considers an approach to the calculation and some principles of calculation of indicators of spare parts sets sufficiency.

������ ���������, ������ �� ������ ��� ��� ���������� ��������� Dz�

The ability to effectively ensure pre-specified level of reliability of the equipment, while main-taining expenditures at a minimum, is one of the foremost requirements and biggest challenges of our time. One of the key elements of the current research is to determine main characteristics of spare parts, e.g. types of spare parts sets, their respective composition, indicators of suffi-ciency of spare elements in spare parts sets, which allows to define the most effective and cost-saving methods of spare elements inventory management for spare parts sets. There have been analyzed some methods for developing the inventory depending on the purpose of the equip-ment, its maintenance and repair, as well as the requirements for the equipment reliability, in-cluding periodic and continuous stocking, periodic stocking with emergency deliveries and re-plenishment by level. To ensure high operational reliability of electronic equipment, mainte-nance and repair, extending the service life of the equipment, a support system is proposed, which includes diagnostic and repair tools, sets of spare parts, etc. In addition, the paper ad-dresses the design of spare parts while taking into account the criteria of reliability of systems operation such as the level of sufficiency, composition and volume of spare parts, which should ensure the functioning of systems with necessary reliability indicators. The suggested methods for spare parts inventory planning and management are based on the most adequate models of reliability that, as a result, provide a significantly more accurate forecasting of the required amount of spare parts and, consequently, a more efficient equipment spare parts inventory plan-ning. The research suggests the main requirements and necessary input data to guarantee the accuracy of such calculations.

Formation of the network of spare elements warehouses

Discusses the redundant machinery construction enterprises. The method of calculation of a network of warehouses taking into account the possibility of different conditions of the reserve from the part to the backup machine. The technique allows you to determine the required number of warehouses of different levels, taking into account the time of delivery of the spare element from the warehouse on the other hand, it is necessary to take into account that the increase in inventory helps to slow down the turnover of reserve elements, increases the cost of the Insurance Fund.

To clarify the standards of spare parts for technical service of autotractors in zone conditions

Organization of technical service of machines under zone operating conditions provides for the possibility of determining the list of units exposed to climate effects and the estimation of zone correction factors to the consumption rates of spare elements during repair and maintenance [1].

Reducing DRAM Refresh Rate Using Retention Time Aware Universal Hashing Redundancy Repair

As the device capacity of Dynamic Random Access Memory (DRAM) increases, refresh operation becomes a significant contributory factor toward total power consumption and memory throughput of the device. To reduce the problems associated with the refresh operation, a multi-rate refresh technique that changes the refresh period based on the retention time of DRAM cells has been proposed. Unfortunately, the multi-rate refresh technique has a scalability issue, because the additional storage and logic overhead on a memory controller increases as the device capacity increases. In this article, we propose a novel redundancy repair technique to increase the refresh period of DRAM by using a universal hashing technique. Our redundancy repair technique efficiently repairs both hard faults, which occur during the manufacturing process, and weak cells that have short retention time using the remaining spare elements after the process. Also, our technique solves the Variable Retention Time problem by repairing weak cells at boot time by exploiting the Built-in self-repair (BISR) technique and Error Correction Code. Our technique outperforms a conventional BISR redundancy repair with very little hardware overhead, and ensure reliability with more extended refresh period in the entire system. In particular, our experimental results show that our BISR technique achieves 100% repair rate at a 384ms refresh period in 1.0e-6 hard fault BER configuration, and reduces the refresh energy consumption by 83.9% compared to the 64ms refresh and 12% compared to the conventional multi-rate refresh technique for the state-of-the-art 4Gb device.

Ensuring the dependability of technical facilities through triplication and quadrupling

Redundancy, e.g. structural redundancy, is one of the primary methods of improving the dependability, ensures failsafety and fault tolerance of components, devices and systems. According to the International Patent Classification (IPC), the class of systems and methods G06F11/18 is defined as «using passive fault-masking of the redundant circuits, e.g. by quadrupling or by majority decision circuits». Obviously, «fault-masking» masks not only faults, but failures as well. The majority decision circuits (MDC) in the minimal configuration implements a «2-out-of-3» choice. According to the above definition, such redundancy should not require a special decision circuit. However, that is not always the case. In cases when the resulting signal out of a quadruple logic is delivered to, for instance, an executive device, a «3-outof-4» selection circuit is required anyway. Another dependability-improving solution is defined by class G06F 11/20, «using active fault-masking, e.g. by switching out faulty elements or by switching in spare elements». The word «active» is missing here, thus we have active and passive fault tolerance. The paper examines passive fault tolerance that uses triplication and quadrupling and compares the respective probabilities of no-failure.The Weibull distribution is used that most adequately describes dependability in terms of radiation durability under the effects of heavy ions. It shows that in a number of cases quadrupling has a lower redundancy than triplication. A formula is proposed that describes the conditions of preferability of quadrupling at transistor level.

LUT’s Sliding Backup

Reliability is one of the most important quality indicators of hardware (and software of course), including field-programmable gate array (FPGA). Fault-tolerant systems (FTSs) use structural, temporal, or information redundancy to ensure the reliability. Passive FTS due to very large redundancy (modular redundancy) produces fault masking. Active FTSs have less redundancy, but require comparatively more diagnostic and reconfiguration time to switch out faulty elements and to switch in spare elements. The author proposes sliding backup (SR) logic for the high reliability FPGA. The capabilities of SR provide modern FPGAs. It is only necessary to ensure the possibility of prompt reconfiguration of all or part of the FPGA and such capabilities are already provided by some manufacturers. This paper focuses on proposed fault Look up Tables (LUTs) scaling, simulation of the self-checked LUT, and fast reverse testing. Evaluations confirm high efficiency of the proposed method.

Ensuring the operability and fault tolerance of machinery by redundancy of replaceable elements

The main task in mechanical engineering is to ensure the efficiency of the machine-tractor fleet. Technical operation of machines requires new organizational and technological approaches to maintaining it in working condition in zonal conditions of use. Since every hour of downtime of this expensive equipment leads to high costs, one of the important tasks will be to reduce the downtime of machines for maintenance and repair. Development of import substitution programs and food security of regions and regions of the country is an important area for scientific and public organizations to solve the tasks set by the government of the Russian Federation. In this regard, the study of foreign technologies and the introduction of their own in the production of machinery and agricultural products. The aim of the study is a mathematical description and justification of fault tolerance of machines to ensure performance at a given level.In the article deals with the issues of ensuring the efficiency of technical systems (machinery and equipment) and planning the number of spare elements during technical service. It is rather simple to establish the cycles of repair time of machines and technology, if the variables of the technical state determining the operability of the machines during operation are deterministic. In practice, in most cases, the performance is determined by the stochastic nature of the influencing factors, forcing to take into account the technical and mathematical methods for their description. In a situation where the recovery time of the failed element is an order of magnitude shorter than the uptime, or the restoration is reduced to replacing the element with a backup, it is natural to accept the model of an instantly restored element.

Recovering from Biased Distribution of Faulty Cells in Memory by Reorganizing Replacement Regions through Universal Hashing

Recently, scaling down dynamic random access memory (DRAM) has become more of a challenge, with more faults than before and a significant degradation in yield. To improve the yield in DRAM, a redundancy repair technique with intra-subarray replacement has been extensively employed to replace faulty elements (i.e., rows or columns with defective cells) with spare elements in each subarray. Unfortunately, such technique cannot efficiently handle a biased distribution of faulty cells because each subarray has a fixed number of spare elements. In this article, we propose a novel redundancy repair technique that uses a hashing method to solve this problem. Our hashing technique reorganizes replacement regions by changing the way in which their replacement information is referred, thus making faulty cells become evenly distributed to the regions. We also propose a fast repair algorithm to find the best hash function among all possible candidates. Even if our approach requires little hardware overhead, it significantly improves the yield when compared with conventional redundancy techniques. In particular, the results of our experiment show that our technique saves spare elements by about 57% and 55% for a yield of 99% at BER 1e-6 and 5e-7, respectively.

Assessment of service quality for complex technical devices based on the Jaynes’ information principle

Arkadiy I. Maron - Associate Professor, Department of Business Analytics, National Research University Higher School of EconomicsAddress: 20, Myasnitskaya Street, Moscow, 101000, Russian FederationE-mail: amaron@hse.ru The Jaynes’ information principle (formalism) advanced for the solution of problems of statistical thermodynamics is applied to the solution of a task of assessing the fairness of a contractor who carries out restoration work on a technical system by the method of replacing elements. The task is the following. The customer possesses a fleet of similar technical devices (for example, cars) certain elements of which are subject to planned replacement. According to the contract, such replacements are carried out by a contractor. Spare elements of three types can be used: new original, new non-original and restored elements. The contract specifies what percentage of spare elements of each type may be used. It is difficult for the customer to check what type of element has been applied. However, for an element of each type it is possible to calculate the average time before the next replacement will be required. The actual average time between requirements for replacement is fixed by the customer. Based on these data and with the help of Jaynes’ information principle, it is possible to find the most objective probabilities of using elements of the various types. Having compared these probabilities with restrictions specified in the contract, the customer draws a conclusion about the fairness of the contractor and, if necessary, takes appropriate action. According to Jaynes’ principle, the most objective are probabilities for which entropy according to Shannon reaches a maximum under the set of restrictions. Respectively, the problem of finding their probabilities is simplified to a problem of finding the maximum nonlinear function under the set of restrictions. In this article, the task is formulated mathematically and solved for a case of three variables using the Lagrange method. Calculations for a real situation from the author’s practice are given.

Improving the Linearity and Power Efficiency of Active Switched-Capacitor Filters in a Compact Die Area

The die size of multistandard wireless transceivers in ultrascaled CMOS is dominated by the baseband low-pass filters (LPFs), which typically count on passive- $RC$ components to define the time constant. To break this area constraint, this paper revisits the active switched-capacitor (SC) LPF for its united benefits of clock-rate-defined bandwidth, accurate cutoff frequency, and small die size due to capacitor-ratio-based sizing and no spare elements. The key challenges of active-SC LPFs are the speed- and linearity-to-power tradeoffs, which are addressed by two circuit techniques: 1) switched-current assisting (SCA) and 2) precharging (PC). The SCA accelerates the charging speed of the integration capacitor, while the PC improves the linearity when charging the load capacitor. Three prototypes (first order, biquad, and fifth-order Butterworth) fabricated in a 65-nm CMOS process validate the feasibility of the proposed SCA and PC techniques.

APPLICATION OF BINOMIAL DISTRIBUTION IN LOGISTICS SYSTEMS

A downtime interval during which a machine is performing no work due to lack of a spare part is an important economical issue for companies. It has to know in advance the need for spare elements to ensure reliable operation of the machines. In order to determine the required amount of spare elements used a scientific approach. In this paper is proposed a well-known statistical approach to inventory management. The binomial distribution permits to analyze without difficulties the operational reliability and calculating the spare parts demand. Some of results are given by engineering software.

The Practical Approach to Freeform Shape Elements Reverse Engineering

Element geometry can be restored with basic measurement techniques. However if the element geometry is too complex (free form surfaces), it is not possible to take all measurements in that way. Example presented in the paper is a drop forged element (car suspension link). In situation when spare element is out of reach (product withdraw from market, producer technological process tooling redesign), the element can be reproduced (singularly or in series, what depends on producer). Reconstructed element is slightly different from a master element (impossible existence of reliably identically designed and manufactured parts), because of measurement uncertainty. Another problem is that original element is usually worn out or during disassembly process can be damaged, so it has different geometry,(when worn out is not fitting to tolerances) than newly manufactured one. The practical approach for reverse engineering is based on: measurement uncertainty extrapolation, 3D part scanning, transformation of point cloud to solid model, composition examination of an alloy. The method is a complex solution that brings: geometrical description and material assignment and heat treatment. Important part of the method is typical measurement techniques. In cases when tolerances have to be preserved, additional tolerance assignment is needed according to linkage between redesigned part of element and parts of other elements in assembly. The insurance of measurement was checked according to typical tolerance of the drop forged element. The retrieved 3D model was compared with virtual mass to real master element mass. The technological tooling reconstructed prototype and element reconstructed prototype have been made. Finally the alloy material is assigned according to measurement result analysis (electron spectroscopy EDS). Proposed example shows many important clues that can be used in order to provide properly redesigned element.

Special characteristics of spare

Some aspects in the problem of management inventory system for spare elements are presented in this paper. The life cycle management of spare elements and their special characteristics is considered in the inventory process. The machine time-down divided with partial weighing range is shown. Emphasis is on the delivery time of spare elements, as the main reason for a fast repair of the failing machine. It’s therefore necessary to predict the demand for spare elements.

Application of statistical methods in forecasting for spare elements demand

The problem of predicting the demand for spare elements is extremely important for continuous operation of machines. It is necessary to know when and how much to order. To calculate and ensure the availability of spare elements, appropriate mathematical models should be applied. The statistical method for predicting spare elements demand is considered in this paper. The study shows how to use a demand forecasting technique for determining the expected number of spare elements. Some of the results are given by engineering software.