Possibility of increasing the switching resource of liquid-metal self-regulating fuses with fusion insert

THE PURPOSE. Assessment of the state of the art in the development of current limiters based on liquid metal self-healing fuses and an increase in the switching life of self-healing fuses with a composite fuse-link.METHODS. When solving the problem, the method of literature analysis was used, as well as the method for calculating dependencies for different materials of the fuse-link, the implemented method of scientific computer mathematics.RESULTS. Literary sources contain information about the designs of liquid-metal self-healing fuses and their research, allowing conclusions to be drawn about their viability and the possibility of obtaining a practical yield. A common disadvantage of the of liquid-metal self-healing fuses design is a limited switching resource due to an increase in the diameter of the fuse-link under the action of arc erosion. A significant effect of increasing the switching resource and the stability of the protective characteristic is possessed by the design of a of liquid-metal self-healing fuses with a composite fusible link. However, in such designs, the switching capacity is reduced. It is shown that the main criterion for the operability of the liquid-metal self-healing fuses with a composite fusible link is the value of the ratio between the value of the shunting resistance and the resistance of the electric ARC. The performance of the liquid-metal self-healing fuses with a composite fusible link is ensured at values of this value below critical.CONCLUSION. The proposed mathematical expression may turn out to be useful in the development of liquid-metal self-healing fuses with a composite fusible link design, for example, when choosing an electrode material, liquid metal, etc. This will significantly increase the switching resource of the liquid-metal self-healing fuses with a composite fusible link. The condition must be taken into account in the parametric synthesis of the current limiter based on the liquid-metal self-healing fuses with a composite fusible link.

Investigation of the Operational and Technological Reliability of the Small-size Internal Threading Process

The article presents the results of research in the direction of improving technological equipment for internal threading of parts in a flexible automated production. Methods for assessing the operational and technological reliability of a flexible manufacturing module (FMM) of thread processing are considered, which can be used as the basis for the developed method of synthesis of its elements. It is proposed to consider the technological system of the flexible manufacturing module (FMM) of thread processing as a system in which transitions from state to state occur under the action of the simplest flows with parameters of the transition probabilities of a continuous Markov chain. The developed mathematical model describing the state of the FMM taking into account the failures of the functioning of its elements, parametric failures, as well as taking into account the recovery after these types of failures, makes it possible to reflect the influence on the operation of the module of the parameters of the flows of failures and restorations of the tool, machine tool, fixture, loading device. The solution of the obtained systems of equations of final probabilities allows for given (or experimentally obtained) intensities of failure streams (functioning and parametric) for FMM threading to obtain the values of the probability of failure-free operation, as well as the probabilities of finding the system in an inoperative state due to corresponding failures. The measures taken make it possible to solve the synthesis problem at the level of structural and layout optimization, so that at the stage of parametric synthesis to determine the elements that are vulnerable according to the developed criterion, the improvement of which will lead to the creation of the most efficient system.

Structural and parametric synthesis of a document management system

The structures representing the document flow processes in an organization are considered by synthesizing them from the simplest structures. Presented in the form of graphs the processes of movement of documents become formalized and unambiguously defined. Using classification of typical structures of information flows and available mathematical model of management system, it is possible to formalize processes of movement of documents and their interaction in the form of management model, and also to make technical specification for development of information system and finished formalized statement of the problem of structure-parametric synthesis

ANALYSIS OF MULTI-THREADED MARKOV SYSTEMS

Known technologies for analyzing Markov systems use a well-operating mathematical apparatus based on the computational implementation of the fundamental Markov property. Herewith the resulting systems of linear algebraic equations are easily solved numerically. Moreover, when solving lots of practical problems, this numerical solution is insufficient. For instance, both in problems of structural and parametric synthesis of systems, as well as in control problems. These problems require to obtain analytical relations describing the dependences of probability values of states of the analyzed system with the numerical values of its parameters. The complexity of the analytical solution of the related systems of linear algebraic equations increases rapidly along with the increase in the system dimensionality. This very phenomenon manifests itself especially demonstratively when analyzing multi-threaded queuing systems. Accordingly, the objective of this paper is to develop an effective computational method for obtaining analytical relations that allow to analyze high-dimensional Markov systems. To analyze such systems this paper provides for a decomposition method based on the idea of phase enlargement of system states. The proposed and substantiated method allows to obtain analytical relations for calculating the distribution of Markov system states. The method can be effectively applied to solve problems of analysis and management in high-dimensional Markov systems. An example has been considered

PARAMETRIC SYNTHESIS OF A MOVING OBJECT STABILIZER

The problem of choosing the variable parameters of a stabilizer of an object which minimize an additive quadratic integral functional reflecting the complex of requirements for a closed stabilization system is considered. To solve the problem a combined method of parametric synthesis of the stabilizer, which is a sequential combination of the Sobol grid method and the Nelder-Mead method, is proposed. At the first stage of the method by applying the Sobolev grid method a working point of the closed system in the pace of its variable parameters is transferred into a neighborhood of the quality functional global minimum point. Then at the second stage the Nelder-Mead method is used to relocated the working point into a small neighborhood of the global minimum. The method proposed comprises a particular algorithm for choosing the weight coefficient of the additive quality functional as well as makes use of the stabilization object state vector main coordinates, which provide the most adequate description of its dynamic features. The properties of a mathematical model of controlled system with discontinuous stabilization process control are studied numerically. The analysis of the plots in the dynamical system state phase space indicates non-spiral approach of the system to its equilibrium state. The synthesized control is realized in the form of a sequence of switchovers.

Laws of Motion of the Lower Extremities and Structural-parametric Synthesis of Electro-hydraulic Executive Modules of the Active Exoskeleton According to the Criterion of Energy Suffiency

The object of the research is the electro-hydraulic executive modules (drives) of the exoskeleton of the lower extremities with a rigid structure of the power frame. The problem of schematic and parametric execution of modules located in the linkage joints of the exoskeleton which is used for verticalization of patients is considered. The aim of the study is to estimates energy consumption, sensitivity, establish a rational structure and parameters of modules that provide programmed movement according to the criterion of energy sufficiency. The laws of motion and diagrams of loads required for lifting a patient from a sitting position are presented.

Parametric synthesis of stabilizing neurocular control of a technological module

The article proposes a new approach to combined parametric synthesis (synthesis in real or accelerated time) of neuroregulators of multidimensional and multi-connected physical systems and technological processes based on the application of the velocity gradient method in differential form and the theory of sliding modes.

Structural-Parametric Synthesis of the RoboMech Class Parallel Mechanism with Two Sliders

This paper addresses the structural-parametric synthesis and kinematic analysis of the RoboMech class of parallel mechanisms (PM) having two sliders. The proposed methods allow the synthesis of a PM with its structure and geometric parameters of the links to obtain the given laws of motions of the input and output links (sliders). The paper outlines a possible application of the proposed approach to design a PM for a cold stamping technological line. The proposed PM is formed by connecting two sliders (input and output objects) using one passive and one negative closing kinematic chain (CKC). The passive CKC does not impose a geometric constraint on the movements of the sliders and the geometric parameters of its links are varied to satisfy the geometric constraint of the negative CKC. The negative CKC imposes one geometric constraint on the movements of the sliders and its geometric parameters are determined on the basis of the Chebyshev and least-square approximations. Problems of positions and analogues of velocities and accelerations of the considered PM are solved to demonstrate the feasibility and effectiveness of the proposed formulations and case of study.