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In this work, a new approach to solving problems of optimal control of manufacture procedures for the production of silica optical fiber are proposed. The procedure of silica tubes alloying by the Modified Chemical Vapor Deposition (MCVD) method and optical fiber drawing from a preform are considered. The problems of optimal control are presented as problems of controlling distributed systems with objective functionals and controls of different types. Two problems are formulated and solved. The first of them is the problem of the temperature field optimizing in the silica tubes alloying process in controlling the consumption of the oxygen–hydrogen gas mixture (in the one- and two-dimensional statements), the second problem is the geometric optimization of fiber shape in controlling the drawing velocity of the finished fiber. In both problems, while using an analog to the method of Lagrange, the optimality systems in the form of differential problems in partial derivatives are obtained, as well as formulas for finding the optimal control functions in an explicit form. To acquire optimality systems, the qualities of lower semicontinuity, convexity, and objective functional coercivity are applied. The numerical realization of the obtained systems is conducted by using Comsol Multiphysics.

In the paper the problems of optimal control of distributed systems described the process of production of quartz optical fiber are considered. This process includes two main stages: the alloying of quartz tubes and the optical fiber drawing from a preform. The following problems of optimal control of distributed systems are formulated: two-dimensional problem with boundary control and one-dimensional problem with distributed observation which describe the process of quartz tubes alloying, and one-dimensional problem with boundary control and distributed observation for problem of quartz optical fiber drawing. For these problems the optimality systems are obtained and the algorithms for their realization are proposed.

The problem of optimal control of a distributed system with a moving thermal source of action is solved. This approach is realized for the process of alloying quartz optical fibers in two-dimensional and one-dimensional formulations. The control problem is solved using variational approaches and convex analysis. As a result of the solution, optimality conditions are obtained in the form of systems of partial differential equations. Numerical studies have been carried out, and management functions have been obtained. Thus, a method for managing a distributed system with a moving source of influence has been proposed and implemented.

A one-dimensional model of quartz optical fibers extraction was considered and the problem of drawing parameters stability was solved. More over two numerical experiments demonstrating the states of stability or instability depending on the values of small harmonic oscillations introduced into the system, as well as on the furnace parameters were performed.

An optimal control problem for a distributed system with compromise control is considered out of this work. The solvability is shown and an optimization system is obtained for the optimal control issue with boundary monitoring and boundary supervision described by equations of melts continuity and movement. An algorithm for implementing the optimal control problem is suggested and the outcome is analyzed. The issue is resolved for a few types of initial conditions used with the radius deviation function from its programmed determination.

One of the most important requirements for optical fibres as waveguiding media is uniformity. Polarisation-maintaining anisotropic fibres contain a special type of nonuniformity, which leads to polarisation cross-talk: optical power is transferred from one polarisation mode to the orthogonal mode. In this paper, we report a technique for detecting and locating such nonuniformities in a PANDA anisotropic single-mode fibre using polarised reflectometry.

A study was performed to determine the regimes to be used for nitriding titanium and zirconium, and a theoretical evaluation was made of the reaction of TiN and ZrN with products from the dissociation of quartz glass at temperatures of 2000 K. The results show the promise of using nitrides of titanium and zirconium as the material for the heaters of a furnace which is used to draw optical fibers of quartz glass.

Anisotropic, polarisation-maintaining fibres have been studied using a reflectometer and integrated optic polariser. Linearly polarised pulses were launched into the fibre under test at different angles between their plane of polarisation and the main optical axis of the fibre. A special procedure for the correlation analysis of these reflectograms is developed to enhance the reliability of the information about the longitudinal optical uniformity ofanisotropic fibres.

One of the stages of producing multilayer films and two-component fibers (including optical fibers) is joint extrusion of two or more molten polymers through a forming channel. Here there is layered or stratified flow [i]. Areas of steady-state stratified flow are the most completely studied where the profile of the flow rate and the position of the interface of the liquid layers is unchanged over the length of the channel [1-4]. Fewer works are devoted to studying the initial area of combined flow where, as is shown in an experiment in [5] and in theoretical finite element analysis [6], the coordinates of the interface vary considerably.

Circulation currents of the polymer melt in the transverse section of the extruder screw channel, temperature fields in the polymer melt and in the solid plug, and the pressure distribution (pressure gradient) along the length of the melting zone have been investigated.

The melting of polycaproamide flake has been studied experimentally on a 32 mm laboratory extruder under various processing regimes. The lengths of the extruder charging and melting zones have been measured, plus the cross-sectional area of the polymer plug along the length of the melting zone.

The form and size of the solid polymer plug in melting polymeric materials in plasticizing extruders depend on the source of heat: external, dissipation of mechanical energy, or preliminary warming of the flake.