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Introduction Soft-tissue origin joint contractures are a common orthopedic problem. It could be due to various etiologies. Treatment options are available from conservative to surgical methods. These joint contractures slowly become irreversible causing impairment in activities of daily routine. The Ilizarov method is a well established and time-tested method used for management of bone pathologies, but its use in the management of soft-tissue origin contractures is also possible. It has an established role in neoosteogenesis and histogenesis. Fixator assisted soft-tissue stretching done at sustained slow pace leads to histoneogenesis that avoids stretching of neurovascular structures and reduces the possibility of recurrence. Aims To determine usefulness of the Ilizarov method in management of joint contractures of soft tissue origin; to meet functional requirements of patients; to study complications of Ilizarov method in management joint contractures due to soft tissue origin. Material and methods A total of 6 cases of soft-tissue origin joint contractures due to tuberculosis, post‑traumatic stiffness, post-burn contracture, deformity due to a snake bite in the age group from 3 to 55 years were treated with gradual distraction of joint with the Ilizarov method from January 22 to October 23. Two cases were of triple knee deformity, two were post-traumatic elbow stiffness, one was post-burn great toe contracture and one was post snake bite valgus foot contracture. All cases were operated with transarticular Ilizarov frame application and gradual distraction of joints and soft tissue with the help of hinge- and rod distractor assembly done. All cases completed follow up of 1 year. Aggressive physiotherapy was given postoperatively. Results All cases obtained a reasonable functional outcome, with no recurrence of deformity. All patients walk independently. Conclusion The Ilizarov method can be used for treating joint contractures due to traumatic and non‑traumatic pathologies.

This article discusses the development of a method for determining reactions in the hinges of a manipulator, based on the classical principle of release from bonds in the example of its main part. A model of a manipulator has been compiled, in which, in the general case, a force F of arbitrary orientation acts on the working platform. The design scheme of the manipulator is compiled and a complete calculation is made under the action of the horizontal component force Fx . By analogy, the reactions from the action of the horizontal Fy and vertical Fz components of forces are determined and general dependencies are derived. Knowledge of the numerical values of the found reactions in the hinges of the manipulator will allow, according to known hypotheses, to calculate this manipulator for strength and rigidity.

Goal . Develop the design of the drive plate chain and methods for determining the optimal parameters of the chain transmission. Methods. Analysis of the designs of standard drive bushing and roller chains, as well as the drive plate chain with internal engagement. Determination of ways to increase the durability of these chains and chain gears from the condition of ensuring the wear resistance of their hinges and increasing their technical and economic indicators. Results . The analysis of designs of standard drive bushing-roller chains and drive plate chains with internal gearing is performed. A promising design of the drive plate chain has been developed. The optimization of transmission parameters, both with standard chains, and with the chain proposed by the authors, providing an increase in their durability and efficiency. In this regard, a method has been developed for determining the greatest elongation of standard chain links, as well as the chain developed by the authors, from the condition of wear resistance of their hinges. A method for determining the optimal transmission ratio of these chain gears has also been developed. It is established that the gear ratio of the transmission with the drive plate chain developed by the authors is determined primarily by the accuracy of manufacturing its hinges. With sufficiently precise manufacturing of chain hinge parts, the gear ratio can be significantly increased, up to u=10 and higher. This will allow you to use gears equipped with this chain in drives with a large gear ratio.

Copyright of National Academy of Sciences of Armenia Reports / Doklady Nacionalnaâ Akademiâ Nauk Armenii is the property of National Academy of Sciences of the Republic of Armenia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The purpose of the work is to study the influence of the control of the elastic and damping characteristics of the cushioning system based on the use of magnetorheological elastomers on the smoothness of the course of wheeled transport vehicles. The technique. The research used the methods of: magnetic field theory, the theory of vehicle suspension, experiment theory planning, and the FEMM code for studying magnetic field characteristics and mathematical modeling of wheeled vehicle movement along roughness in the Delphi environment. Results. Designed, researched and patented designs of elastic hinges of the suspension arms with magnetorheological elastomers. The relative boundaries of changes in the elastic modules and losses of these hinges are determined when controlling the characteristics of the suspension in order to improve the smoothness of the wheeled vehicle. Scientific novelty. For the first time, the feasibility of using magnetorheological elastomers to control the elastic and damping characteristics of the cushioning system of wheeled vehicles has been investigated, and the requirements for control laws have been determined, which make it possible to increase smoothness by more than 40 %; it is established that the control of the loss modulus has a greater effect on the improvement of smoothness of motion than the control of the elastic modulus. Practical value. The design has been developed and the relative boundaries of changes in the modules of elasticity and loss of hinges with magnetorheological elastomers during their control have been determined, which will make it possible to formulate requirements for elastomers when developing promising hinge designs for vehicle suspension systems.

Objectives The aim of the study is to develop a model for assessing the reliability of frame systems, taking into account the redistribution of forces between vertical structures when plastic hinges are formed in them from horizontal seismic effects.Method The research method is based on the analysis of the schemes of mechanisms for the transition of frame systems to limit states, as well as probability theory, random processes and system reliability.Results Based on the analysis of the paths of transition of statically indefinable frame systems to failure states due to the formation of plastic hinges at the junction points of the posts with crossbars, a block diagram of the system elements connection has been developed, presented as a separate redundancy scheme. The expressions for estimating the probabilities of switching off the conditional elements in the computational model and transitions of the system, both to the backup and to the failure states are presented. Expressions are proposed for assessing the survivability of frame systems with a decrease in static indeterminacy due to the formation of plastic hinges in structures. The calculation example is given.Conclusion The proposed model for assessing reliability allows, in contrast to the parametric model, to evaluate the reliability of structures with regard to the redistribution of effort in structures with damage accumulated in racks in the form of plastic hinges, and to identify reliability reserves embedded in statically indeterminable systems under strong seismic effects.

Copyright of National Academy of Sciences of Armenia Reports / Doklady Nacionalnaâ Akademiâ Nauk Armenii is the property of National Academy of Sciences of the Republic of Armenia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Stratum Plus Journal is the property of P.P. Stratum plus and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Stratum Plus Journal is the property of P.P. Stratum plus and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this article, the study of the strength of a 25-storey reinforced concrete frame against progressive collapse under fire conditions is presented. Taking the angles of disclosure of plastic hinges as norming for the strength of reinforced concrete elements, a computer tech- nique program has been developed, included in PR Wolfram Mathematica 10 for the dynamic calculation of compressed reinforced concrete elements under fire exposure on the basis of the conducted experimental studies. Dynamic calculation of the strength of eccentrically compressed reinforced concrete columns was carried out, working in normal conditions and under high temperatures. The diagram «moment-curvature» and the graph of change of the static and dynamic strength of the column depending on the temperature were developed. Nonlinear dynamic analysis of a 25-storey reinforced concrete frame was conducted, taking into account the changes of the dynamic characteristics of reinforced concrete elements under fire and, the estimation of resistance of the frame was given.