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ACTUAL PROBLEMS OF AVIATION AND AEROSPACE SYSTEMS
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Innovations in aviation and cosmonautics-2011

Scientific practical Conference of young scientists and students of the Moscow Aviation Institute

(April 26-30, 2011, Moscow, Russia)

Stream "Mathematical problems in the aerospace industry"

A.A.Puntus

Moscow Aviation Institute (State Technical University)

Moscow, Russia

In order to promote the research work of students and young scientists of MAI, a scientific practical conference of young scientists and students of Moscow Aviation Institute "Innovations in aviation and cosmonautics-2011" was hold on April 26-30 of 2011. This conference is the third annual conference of the Moscow Aviation Institute, which is conducted to develop research work of students and young scientists, and its main focus is modernization of Russia and introduction of innovative technologies and products. At the same time, this scientific-practical conference, "Innovations in aviation and cosmonautics-2011", is devoted to the remarkable date, the 50-th anniversary of the flight of Yuri Gagarin into space.

The holding of this conference is certainly one of the most important events this year, which is the year of Russian space exploration as announced by the order of the President of Russia, and is one of the commemorative activities to maximize the reach of the youth audience, increase its knowledge about our country's role in space exploration and about modern and future Russian space exploration, and increase interest in careers that provide a progress in cosmonautics. The goal of this conference is to attract students and young scientists in Russia and abroad to address urgent problems of modern science and to promote the integration of science, production and education, the value of new knowledge that forms the basis of technological innovation, the development of innovative activity, and professional growth of young professionals.

At this conference, participants had a popular the direction of "Mathematical problems in the aerospace industry", which has been implemented in the sections "Application of mathematical methods to engineering and economic problems" and "Mathematical and software systems for information processing and management". In these sections, which were chaired by professors of the department "Applied Mathematics and Physics" of MAI A.A.Puntus and A.V.Panteleyev, respectively, informative reports were presented by undergraduate and graduate students of the institute. Main advantage of these reports was the objective and interesting information presented in a modern way, which showed an increase in scientific interest of young people  to applied research, technology, innovation and scientific creativity. Abstracts of these reports are presented in this publication.

On November 26 of 2009, the Moscow Aviation Institute is promoted to the category of the "national research university in the field of training in all aspects of designing and testing aircrafts, aerospace and rocketry" by order of the Ministry of Education and Science of the Russian Federation. The new status of MAI is not only a recognition of the undoubted merits of the university but also the great responsibility of all university staff, and the incentive for hard and creative work. This category recognizes the priority for science, education, high technology and culture. Availability of qualified personnel and international recognition of the scientific schools, the long tradition of MAI to ensure training of highly qualified specialists, and preservation and development of teaching and laboratory facilities allow us to look optimistically to the future of Russia's leading aerospace university. Modern MAI is the leading aviation university in Russia, a multidisciplinary educational and research center, which provides training in a wide range for all sectors of aviation and space science and industry. The goal, which is facing the institute staff to implement programs of the further development of MAI, is to move to a new level of training required by the high-tech industries in today's innovation economy, in other words, to create a unified educational environment of university, research centers, and the enterprise sector.

According to the results of the conference, which was held on April 26-30, the authors of the best reports were given the opportunity to publish articles in the leading journals, as well as were given the recommendation to participate in the conference, XI all-Russian exhibition of scientific and technical creativity of youth "STCY-2011". This publication presents abstracts of students and young specialists on the direction of "Mathematical problems in the aerospace industry", presented at the conference "Innovations in aviation and cosmonautics-2011", which was held on April 26-30 at MAI.

 

Member of the Conference Organizing Committee,

the Chair of the Section "Application of mathematical methods to solve engineering and economic problems", Stream "Mathematical problems in the aerospace industry"

Professor A.A.Puntus.

 

А.А.Ermakov, P.A.Fomkin, S.N.Padalko.

(Moscow Aviation Institute, State Technical University, Moscow, Russia).

Mathematical methods in the field of microbiological safety: detection and localization of microorganisms in the image.

The task of pattern recognition of microorganisms is just "first step", or so called preprocessing in resolving task to "the higher level" (for example the recognition of microorganisms).

The task of detecting the microorganisms on the image appears more than simple for the human sight; however, with an attempt at the construction of the automatic acquisition system of microorganisms it is necessary to contend for the sake of the following complexities:

-        Strongly being varied exterior view in different microorganisms;

-        The possible presence of specific features substantially complicates automatic recognition;

-        The conditions for survey (illumination, the color balance of camera, the distortions of image, by system's optics, image quality) to a considerable degree influence the obtained image of microorganisms;

The existing algorithms of the detection of microorganisms can be broken beside two wide categories. In the first category the methods, which are repelled from the experience of man before the recognition of microorganisms and which make the attempt to formalize and to algorithmize this experience, are placed, after constructing beyond its basis mathematical [mozhel] of recognition. The second category rests beyond the set of instruments of pattern recognition, examining the task of detecting the microorganisms as a special case of the task of recognition.

 

A.V.Teryohin, A.A.Puntus.

(Moscow Aviation Institute, State Technical University, Moscow, Russia).

Strap down inertial system as a basis of system of orientation in space.

In the given research work a strap down inertial system based on three axial gyroscopes and accelerometers, edited satellite navigational system, for system engineering of orientation of a motorcycle research and the analysis of a possibility of use is conducted in space and by that a possibility of installation of the fact of its falling at movement. Besides, the analysis of the various integrated means of safety, search of various necessary devices and solutions for prevention and the prevention of accidents, and also recommendations about their improving and introduction is carried out. Mathematical security is considered with reference to a subsystem of security of the fact of detection of a vehicle in special situations. In work the methods described for creation of onboard intelligence systems of pilot less flying machines and various vehicles are used, functional algorithms, models of errors are considered. Also motorcycle movement at turn is modeled, on purpose to learn a maximum possible angle of a deviation from a vertical. Besides, during the given work economic validity of development of the given device with a view of operative reaction to incidents is affected. Thus, the purpose of the given work is the analysis of use of onboard intelligence systems in various cases.

Within last decade, development of onboard intelligence systems is one of the basic directions of research of motor industry, with a view of a raise of safety and comfort of four-wheel vehicles. These new process engineering's are already presented in the automobile market and their development, certainly, is fast and effective. However, such process engineering's in motorcycles, with a view of a raise of safety and comfort of drivers, have not received now so a wide circulation and undoubtedly should be are worked in more details. We will reduce the detailed review of some onboard intelligence systems, making the greatest impact on safety and awareness of the motorcyclist. It is the notification about movement velocities, that is informing of the driver in those situations when the motorcycle velocity exceeds admissible, on the given site of road. The information on an admissible velocity undertakes from maps and co-operates with the data received from a motorcycle. The prevention of turn radius is intended to notify the driver about a high risk not entrances in turn. The information that the velocity is excessively high, arrives by сравнивания the planned profile of a velocity, acceleration and jerk, and also the information received of a road map. Recommendations about a velocity, at entrance in turn, represent values of a velocity which the motorcycle should have in the following some seconds for a successful input in turn. The prevention of face-to-face collision works when there is a risk of origin of collision with an obstacle, discovered in the field of motorcycle determination. It is reached by installation in a forward part of a motorcycle of laser reading out installation which not only discovers an obstacle, but also estimates weight of collision. This function consists of two minorants: One is a safe distance, namely, notifies, if the distance is too close in comparison with time of a response of the driver and the second is a safe ratio a velocity-way, that is the prevention if ahead the car intersects a trajectory or slowly goes, and the driver does not react, probably that he has turned away.

As a result of scientific work the object in view has been reached, namely: the possibility of use of onboard intelligence systems as a basis for creation of system of safety of the various vehicles realizing the information to the driver about a velocity and a position of the nearest vehicles, the prevention of the driver in case of potentially dangerous evolution, from the point of view of possible collision is shown. Models of possible errors, algorithms of orientation, and also use of onboard intelligence systems for correction of output data's with a view of a safety and comfort raise are taken apart at movement of vehicles.

 

A.I.Yemel 'kin, A.A.Puntus, V.I.Polezhaev.

(Moscow Aviation Institute, State Technical University, Moscow, Russia).

Parametric study of heat transfer and flow structures in an inclined layer in the heated end face.

Convection and heat transfer in an inclined layer in the presence of a longitudinal temperature gradient (the case of heating the layer from the end) have been studied much less than in the case of an inclined layer in the transverse heat input. However, this case is also interesting for the theory of heat convection and has a practical value (convection during crystal growth in a horizontal "boat", fueled by lower layers in the vertical shafts, cooling down wells, advective flow in the atmosphere, ocean, asthenosphere) and others. In this paper we continue the parametric study of convection and heat transfer in inclined layer without the assumption of a periodic structure along the fiber is treated with a heated face of the horizontal and vertical layers heated from below, as well as the intermediate position, achieved by turning the layer. Calculations were performed for different Raleigh numbers and aspect ratio to find the common modes and characteristics of the flow and heat transfer. As a starting with the length of the layer, as well as for tests taken the case of a square area at different angles. The focus is on finding the parameters for which realizing the extreme heat.

Calculations are based on a networked computer laboratory IA Mech RAS.

 

A.I.Safonov, O.V.Kholostova.

(Moscow Aviation Institute, State Technical University, Moscow, Russia).

Construction of a non-resonant periodical solution in Hamiltonian systems in the neighborhood of a stationary rotation.

In many devices of the aerospace engineering one of the operating modes is the mode of a stationary rotation. It is of interest to study the influence on such motions small periodical in time and angular coordinate perturbations. The first step in this research is to examine a general non-resonant case, when there're no special form constraints.

The motion of the Hamilton system with two degrees of freedom, containing a small parameter, is considered. It is assumed that the generating system is autonomous and contains a cyclic coordinate. The perturbed part is periodic in time and in the specified coordinate. It is also assumed, that the generating system has a stationary rotation and the corresponding motion equilibrium of the reduced system is stable in the linear approximation.

The goal of this work is to determine conditions of existence and to construct a non-resonant periodical solution of the total system in the neighborhood of the stationary rotation of the unperturbed system.

Using the Deprit-Hori's method and the Poincaré's method of a small parameter an algorithm of constructing a non-resonant periodical solution of the system in the neighborhood of the stationary rotation of the unperturbed system is made. For this solution the positional coordinate and the conjugated momentum are periodical with the period equal to the period of perturbations, as well as momentum conjugated with "almost cyclic" coordinate. Explicitly written out the solution to the first approximation of the small parameter. Following conditions, when this solution exists, are found:

1) fluctuating frequency of a cyclic coordinate is integer;

2) small oscillations frequency of the unperturbed reduced system in the neighborhood of the equilibrium is not integer;

3) there are some special restrictions at the harmonics of the perturbed part of the Hamiltonian, that only depend on the "almost cyclic" coordinate and time.

As an application it is considered a model problem of the spherical pendulum with the point of suspension that performs horizontal oscillations at an arbitrary frequency and small amplitude. A periodic solution in the neighborhood of it's conic motion in the case of vibrating point of suspension is constructed.

This work is supported by "State support of leading scientific schools" (SS-3797.2010.1)

 

A.M.Bulatova, A.A.Puntus, E.B.Kuznetsov.

(Moscow Aviation Institute, State Technical University, Moscow, Russia).

Problem about dynamics of nonlinear viscously plastic rod.

The purpose of the given scientific work is the numerical solution of a problem about longitudinal blow on a viscously plastic rod by means of chosen for this numerical method. The physical model of a considered problem is investigated by means of its information to corresponding mathematical model of viscously plastic blow. The given mathematical model represents a boundary value problem which in turn for the purpose of its approached numerical solution is reduced to a Cauchy problem. Thus, a main objective of the given work is research of longitudinal blow on nonlinear viscously plastic rod.

For a solution of the given considered physical problem, and, hence, its mathematical model, one of numerical methods is applied. Subject domain analysis is spent, the representation is formulated and the choice of a method for a problem solution is carried out. The following chosen numerical methods will be applied to this purpose - a method of shooting and a Runge-Kutt method of the fourth order of accuracy.

So, in the given work one of approaches to a problem solution about longitudinal blow on one of end faces originally the motionless semi limited rod within the limits of its viscously plastic model is considered. Problem statement is reduced to the following. The origin of co-ordinates is located in the rod beginning, and the rod axis coincides with an abscissa axis so that its points belong to a semi-infinite interval of the given axis. In an initial considered instant on a rod end face blow therefore the rod material starts moving is made. At a solution of the given problem we consider a rod thin and it is neglected by a side swelling and influence of cross-section strains. We suppose also that contracting voltages are positive and displacement of all points of any cross-section are equal and parallel to a rod axis. Further the equation of movement worked out thus and special attention is considered thus converted on - a velocity of transition of points of a rod. Besides, the indicial equation describing mechanical properties of a viscously plastic material and establishing connection between a velocity of a strain and voltage of the considered rod is introduced. The equation of this kind describes a plastic strain at high-speed blow. In the equation received thus the magnitudes defining a material of a rod are considered as constants: a static yield point, and also the data of a viscously plastic material, characterizing influence of velocities of a strain. In case of small strains at equation construction connection of a velocity of a strain with displacement is considered.

For a solution of the boundary value problem put thus, namely for the approached determination of a solution of a boundary value problem, the method of an information of the given solution to a multiple solution of a Cauchy problem by means of a known method of the shooting which essence consists in a multiple solution of a Cauchy problem for the purpose of deriving of the approached numerical solution of the given boundary value problem is carried out. Values of the outcomes received by means of the developed program in which the used numerical method has been realized, are shown in the corresponding table and their comparison with the exact values received analytically is spent.

Outcome of the given work is the made and realized program of calculation. In the basic final outputs the received numerical values of magnitudes of a velocity of a strain have special value. The discovered values allow to estimate rod acceleration that as a result allows to draw conclusions on a strain of a viscously plastic rod. The given values can be used at practical calculations of the corresponding applied problems connected with performance of many technological operations in mechanical engineering, aircraft, building and other numerous branches at shock handling and destruction of various materials.

The problem about transition of points of a rod at blow on one of its end faces has independent value in the mechanic and represents, for example, interest for the theory and practice of deriving of multilayered materials by explosive process engineering.

 

A.O.Simonenko, A.V.Panteleyev.

(Moscow Aviation Institute, State Technical University, Moscow, Russia).

Estimation of economic efficiency of investment projects in conditions of uncertainty.

The interval analysis, as an effective method of work with uncertainties is considered. At use of the interval analysis the data which is not giving in to the exact description, is represented as the interval numbers set by an interval of values, instead of the fixed quantity. The interval and interval uncertainty are initial concepts of the interval analysis. Interval uncertainty is a condition of incomplete knowledge of quantity for which is known only the belonging to some interval, which is the closed numerical interval. The mathematical discipline, studying problems with interval uncertainties and methods of their decision, is called as the interval analysis.

Newton's interval method is one of the basic methods of search of roots of the nonlinear equations in the interval analysis. It is based on means of Newton's operator, which decrease the width of an initial interval with each step, and the final interval turns out with the set accuracy.

However the classical version of a method has a number of essential restrictions: as an initial interval it is possible to set only an interval which is not containing neither zero, nor infinity, as well as the given method does not allow finding all roots of the equation on the specified initial interval, but only one root.

In the given work the algorithm of the modified Newton's interval method of the decision of the nonlinear equations which possesses a number of important advantages in comparison with its known classical variant is created, in particular, allows finding all roots of the nonlinear equation on any initial interval.

As a basis of the modified interval method of Newton the algorithm of a classical variant of a method in which operation of division into an interval containing zero has been introduced is taken. Further the method has been changed and adapted for simultaneous search of all roots of the equation. The essence of the modified method consists in step-by-step reduction, splitting of an initial interval and localization of roots, namely, finding of a final interval (or several) with demanded accuracy.

By means of the developed modification of a method applied problems of an estimation of efficiency of investment projects which generally can't be solved by means of a classical variant of the given method are solved.

The detailed algorithm of application and the software of methods of an estimation of economic efficiency of the investment project of modernization of manufacture without the inflationary factor and taking into account the inflationary factor are created. Also the problem of calculation of the basic cost indexes of activity of the enterprise is considered, and is created algorithmic and the software of application of methods of the interval analysis for its decision. Efficiency of the software is shown on modeling examples.

 

V.N.Panovskiy, A.V.Panteleyev.

(Moscow Aviation Institute, State Technical University, Moscow, Russia).

Implementation of contractors in the form of a program in C#.

The purpose of this work was to create a program in C#, which solves problem of execution of restrictions with contraction operators of Gauss, Kravchik and Gauss-Zeidel.

Problem of execution of restrictions imply a set of relations (or constraints), relating the variables belonging to some areas, which are assumed for simplicity as intervals. The solution to this problem will allow finding the solutions of systems of both linear and nonlinear equations or inequalities. When compressing the problem of execution of restrictions source parallel tope, or an interval vector (Cartesian product of intervals) is replaced with a smaller area. The set of solutions in this case remains unchanged, thus effectively applying contraction operators, the initial region will converge to the solution set.

Classic Gauss elimination algorithm (solves the problem of execution of restrictions of a linear system with a square matrix) has been modified in accordance with the properties of interval matrices and vectors. Contraction operators of Kravchik (problem of execution of differentiable restrictions, where the number of restrictions equals the number of variables) and Gauss-Zeidel (solves a problem similar to the method of Gaussian elimination) can be obtained by using interval arithmetic to a method, based on the notion of a fixed point.

The result of this work is the creation of a library on the algorithmic language C#, which implements the previously mentioned contraction operators. It is planned to supply the created library with contraction operators based on a parallel linearization, forward and backward method and others. The importance of the contractors comes from the fact that they are a fundamental component of the solution operators: methods for solving square systems of nonlinear equations, global optimization (algorithms of Moore-Skelbo, Hansen), the minimax optimization. Solution operators do not directly use the inclusion functions and interval calculations, they only create the strategy of contraction operators and ensure a way out of impasses (e.g., by bisection of the original area and applying the algorithm to the resulting sub-areas).

 

D.V.Metlitskaya, A.V.Panteleyev.

(Moscow Aviation Institute, State Technical University, Moscow, Russia).

Application of genetic algorithms with binary and real coding to an optimal control problem of the aircraft.

In the given work genetic algorithms of conditional optimization with binary and rуal coding are considered.

Genetic algorithms concern met heuristic methods of search of a conditional global extreme of functions of many variables. At the heart of their work the modeling of some natural ways of optimization (evolution) lies: genetic inheritance and natural selection. Essence of the mechanism of natural selection: in the course of evolution the most adapted individuals survive and breed. Thanks to the mechanism of genetic inheritance their descendants keep the basic qualities of parents, and being exposed to casual mutations, get also a number of new properties. If new properties are useful, they also remain and inherited. Average fitness of the individual with each generation thus grows.

Genetic algorithms with binary and real coding find the decision which can differ a little from optimum, but thus is comprehensible from the practical point of view. Genetic algorithms find a global extreme of functions with difficult structure of level lines, and also find the decision when almost completely there is no information on properties of investigated function.

Working out of algorithmic maintenance of genetic algorithms is necessary for the decision of various applied problems.

In work application of genetic algorithms of conditional optimization with binary and real coding to a problem of search of optimum control of continuous dynamic systems is considered. The technique of application of genetic algorithms to the considered problem is developed. On its basis the applied optimal control problem of the aircraft - a control problem of the missile "air-to air" average range has been solved.

It is required to translate the missile from the set initial position with the set initial speed and a trajectory angle of slope in a point with the set height and the maximum range at fixed time of flight of the missile. For this purpose it is necessary to generate the control providing flight of the missile on energetically favorable trajectory. Control of the missile is made by means of control of a cross-section overload. Control process of the missile is considered in the determined statement. On all trajectory of operated flight process of realization of the set overloads is considered without inertia - at each present situation of time conformity between an overload and a balancing angle of attack is established. It is considered that the missile is counterbalanced concerning the center of weights, i.e. is in a balancing mode. Influence of all set of random factors and simplifications is considered by introduction of an additional making cross-section overload (equivalent loading). Acceptance of such assumptions has allowed not describing rotation of the missile round the center of weights that has essentially simplified system of the equations of movement of the missile. Rocket movement is considered only in a vertical plane, in one channel of prompting.

By means of the offered algorithms optimal control of the missile, and an optimum trajectory of flight of the missile have been found. Comparison of the received results with results of other methods which has shown efficiency of genetic algorithms has been made.

 

D.G.Filimonov, A.A.Puntus, E.B.Kuznetsov.

(Moscow Aviation Institute, State Technical University, Moscow, Russia).

Definition of limiting conditions of elastoplastic bodies.

The given scientific work is devoted the analysis of the intense-deformed condition of a rod in the field of fluidity of the diagram of a stretching-compression. The considered area superimposes essential restrictions on use of mathematical methods owing to that the exposition of the intense deformed condition leads to singular differential equations because of rushing in zero of a tangential stiffness factor. Deriving of algorithm of a regularization of the problem was a primal problem, allowing to avoid singularities and to use traditional numerical methods for a task in view solution. At a solution of problems about deformation of bodies from an ideal elastoplastic material at some values of exterior forces limiting conditions - equilibrium configurations in which strains are converted in infinity are reached. Corresponding loading is called as limiting. Universal method of solution of problems on elastoplastic deformation of bodies with arbitrary geometry is the finite element method. After digitization of an initial differential equation by a finite element method procedure of definition of equilibrium configurations of a body is reduced to step by step integration of nonlinear system of ordinary differential equations. In a limiting condition of a body the matrix of this system is degenerated. In standard procedures of step by step integration of system of ordinary differential equations as deformation parameter exterior force is used. In neighborhoods of maximum loads it is necessary to use small pitches on loading for definition of equilibrium configurations. Thus repetitive processes of an improvement of a solution converge slowly or disperse.

In the present work the finite element method is supplemented with a method of prolongation of a solution on the best parameter which reduces procedure of definition of equilibrium configurations of a body to step by step integration of system of ordinary differential equations. The algorithm of regularization in which basis the method of prolongation of a solution on the best parameter lies is with that end in view offered, allowing to avoid the singularity in the field of fluidity of the diagram of a stretching-compression. This algorithm consists of following basic stages. At first to an initial differential equation the finite element method is applied. Practically it is realized as follows. The considered rod from an elastoplastic material is divided into some number of finite elements. In each finite element the system of indexed knots in which values of required function are unknown quantities gets out. To each indexed knot basis function such is assigned that in this knot it is equal to unit, and in remaining indexed knots of rated area - to zero. The number of basis functions is equal in rated area to number of indexed knots, and for various knots they possess property of linear independence on all rated area. The problem solution approximately is under construction in the form of a linear combination of basis functions on all indexed knots of rated area. This solution is substituted in a differential problem, and as the solution approached, outcome of substitution will be not identical zero, and some functional discrepancy. The received system of the linear algebraic equations is differentiated on the best parameter and dares concerning the received derivatives. Then the system of differential equations is integrated by means of one of methods of numerical integration.

The finite element method applied in work is almost added by a method of prolongation of a solution on the best parameter which has allowed to reduce considered procedure of definition of equilibrium configurations of a body to step by step integration of system of ordinary differential equations. Efficiency of algorithm is shown at a solution of a test problem about a stretching of a rod from an ideal elastoplastic material.

E.A.Alyoshina, A.V.Panteleyev.

(Moscow Aviation Institute, State Technical University, Moscow, Russia).

PSO Application to the optimal control of discrete deterministic system.

Particle Swarm Optimization (PSO) is met heuristic and Swarm Intelligence method for searching the global extreme. The idea of PSO is to simulate the behavior of flocks of animals in search of food. When implementing the PSO the following basic principles are used:

-       the extreme is searched by set of individuals (particles);

-       each particle receives information on the movements of its neighbors;

-       each particle moves towards the target by imitating the neighbor's actions;

-       the information about the purpose, i.e. the value of the objective function is also used;

-       each particle uses its own past experience.

In solving the problem of synthesizing an optimal control of discrete systems by the PSO the control vector is optimized, so that the value of criterion has been extreme. During calculations the state vector of the system is determined by state equations using the initial state and the control vector.

We created a program able to solve the problem for the case of linear system and quadratic or linear-quadratic criterion using different parameter values of the method.

The software is formed on the C# language in the Microsoft Visual Studio 2005. The user interface allows setting the parameters of the problem and of the algorithm, using the modification of the algorithm and analyzing the results in a convenient graphic form. At the end of computational process the result is displayed in tabular form, as well as graphs of the optimal control and state vectors. The result can be placed in a file for later use. Due to the random nature of the PSO there is an opportunity to produce a series of solutions of the problem with logging results in the program.

With this program, test problems whose solution can be compared with the solution obtained analytically have been solved. In solving the example we chose modification of the PSO with a local search, because it is the most effective.

Testing of the developed software shows that the PSO succeeded solving this class of problems. With increasing lifetime of the system solution accuracy becomes worse; however, when using the algorithm with local search, it is acceptable in comparison with traditional techniques of optimization.

In future research we should expand the range of the problems to be solved by PSO. We must also focus on the optimal control of continuous deterministic systems in order to have the possibility of solving more complex problems.

1.           Kennedy, J. and Eberhart, R. Particle Swarm Optimization.

          http:// www.engr.iupui.edu/~shi/Coference/ psopap4.html

2.           Panteleev A.V., Bortakovsky A.S. Control theory in examples and problems. - М: High school, 2003.

3.           Alyoshina E.A., Panteleyev A.V. Algorithmic and program support elaboration of PSO method//Scientific bulletin MSTUCA, © 145, 2009. P. 32-39.

 

E.A.Vishenkova, O.V.Holostova.

(Moscow Aviation Institute, State Technical University, Moscow, Russia).

Studying an effect of high-frequency horizontal vibrations on the mechanic system such as a double pendulum.

Studying an effect of high-frequency horizontal vibrations on the running devices and machinery in the aerospace sector is an actual area of the scientific researches. Any kind of such researches begins with an examination of model problems, among which the interest is a pendulum-type model.

In this work the motion of a double pendulum - a system consisting of two hinged thin uniform rods revolving around horizontal axes is investigated. It is assumed that the point of suspension, which coincides with the end of one of the rods, performs horizontal high-frequency harmonic oscillations of small amplitude.

This work's goal is to study the stability of four different positions of relative equilibrium of the double pendulum on the vertical as well as the question of the existence, bifurcations and stability of the lateral high-frequency periodical motions of the pendulum.

It is shown, that among the four different positions of relative equilibrium on the vertical only the lower ("hanging") position may be stable in case when the oscillation frequency of the point of suspension doesn't exceed a certain limit. It is established, that this equilibrium is stable for the majority of (in the terms of Lebegue's measure) initial conditions and formally stable.

It is shown that in case of pendulum with two uniform rods the lateral periodical motions exist only when a lower position of relative equilibrium is unstable.

The number of lateral motions may be from one to six, and each one has a symmetric pair. One or two pairs of motions are stable for the majority of initial conditions and formally stable, others are unstable. In the plain of angular quantities geometrical locus is built, where these quantities may (for different frequencies) receive "average" values of angles of derivation of the pendulum rods from vertical positions, for the periodical motions has been built.

This research is examined using the method of Deprit-Hory, method of normal modes, KAM-theory and Computer Algebra Methods.

This work is supported by "State support of leading scientific schools" (SS-3797.2010.1).

 

I.V.Gucaev, A.G.Golovachev.

(Moscow Aviation Institute, State Technical University, Moscow, Russia).

Abstract deduction in decision-making systems.

This paper observes the problem of solutions search with the use of knowledge base, based on the abstract associative deduction. Besides it investigates the effectiveness of an abstract approach to the problems of providing comprehensive knowledge and recognition of the situation by the mobile robot (UAV).

For efficient logic deduction in application task an intelligent system should possess imaginative situational thinking, based on similarity-difference (reducibility) operation. There exist a number of techniques that allow reducibility: neural networks, soft computing, fuzzy logic, abstraction, etc. The abstraction approach has a significant advantage over other models. Fuzzy logic, neural networks and other generalizations of the classical logic act in the same base space. Abstraction works in two spaces - the original and the abstract.

Abstraction - is a logical process that maps the representation, the original description of the problem to abstract representation, much more compact and easy to handle. Abstraction allows the decision-making agent to allocate a substantial connections between the objects. Mapping objects to abstract space establish links between objects of different classes more flexibly. Comparison operation between members from different classes are produced in an abstract space, which it introduced a partial order. From a computational point of view an abstraction - technology for practical learning and planning algorithms in large-scale applications (partial implementation of an abstraction is made in the language Prolog through the inheritance tree).

The act of abstraction is executed in three steps. The first makes the display of objects from different basic spaces into a single abstract space. Objects are transformed into abstract states. Second step produced comparison of this abstract states (by unification). The third does the reverse mapping from the abstract space into the original, in which the agent returns to the set of possible solutions. The number of solutions depends on the level of abstraction. Selecting the most appropriate solution also can be provided by the unification operation, which involves the potential solutions and the knowledge base of decision-making agent. However, it is impossible to describe all the environment situations, events and their links. Abstraction is looking the most likely solution based on accumulated experience.

Unification in logical deduction - is process of casting different states of the objects to the same value. In this case, unrelated values from one state to be filled with values from another state. Thus, if the unification operation involves two objects and each associated with own values through the properties and components, and then performing a comparison. If an object is not linked, then performed equating values. And if the object is involved in the unification with the presence of unrelated parts, these parts take their values from the same parts of another state. Unification can be used as a comparison and as a reduction to the same values. Unification-comparison establishes the possibility of potential equivalence of two objects of different classes.

In the process of solving an application task, such as automatic flight control, there is an acute problem of the knowledge base for decision-making. Achieving completeness can be arrived through the reducing to known situations with use of abstract associative technique. Quality of produced solutions depends on the quality and quantity of the knowledge base of decision-making.

 

I.F.Dmitrakov, A.V.Panteleyev.

(Moscow Aviation Institute, State Technical University, Moscow, Russia).

The optimal control synthesis of the deterministic systems by means of simulated annealing and differential evolution methods.

Problems of search of unconditional and conditional global extreme of functions of many variables and search of optimal control for the discrete and continuous deterministic systems are considered. For their decision it is offered to use met heuristic optimization methods, namely the simulated annealing method, the differential evolution method and their modifications. Detailed algorithms of application of the methods set forth above are generated.

The differential evolution method is based on the analysis of evolutionary processes. Feature of algorithms of differential evolution is use of distinctions between individuals (values of argument of criterion function), realized by the linear operator, and named "differentiation".

The simulated annealing method is based on the analysis of process of freezing of liquids or recrystallization of metals in the course of annealing. Algorithms of simulated annealing with some probability suppose transition in a condition with higher value of criterion function in the course of decision search that the point could leave a vicinity of a local minimum.

The software environment of visualization of process of work of optimizing algorithms in which the set forth above methods are added is developed.

The given software allows to:

-        work easily with parameters of the checked up method;

-        analyze efficiency of its work on test functions;

-        analyze a method convergence;

-        "visualize" the process of its work;

-        set parameters of problem statement  conveniently and to receive the decision: in case of search of optimal control  by the deterministic systems  - the control, a corresponding trajectory and value of quality functional, in case of search of a global unconditional or conditional extremum of function - its value and corresponding argument;

-        effectively to form a policy of method's parameters choice that has crucial importance at use of met heuristic methods of optimization;

-        see intermediate results of the account;

-        spend convenient comparison of the chosen method with other methods of global optimization for the subsequent analysis of results and delivery of recommendations.

Efficiency of the developed software is shown on model examples. Applied problems of optimum control  by two chemical processes are solved. At a correct choice of parameters of methods, results practically coincided with the exact values received analytically.

 

M.A.Lebedev, A.A.Puntus, V.I.Polezhaev.

(Moscow Aviation Institute, State Technical University, Moscow, Russia).

Modelling of the current, heat exchange and the hysteresis phenomena in inclined layers.

The problem about a convection and heat exchange in inclined layers is considered at heat stream directed across a layer. Depending on an angle of slope here operates two mechanisms of a thermal gravitational convection corresponding to two limiting cases: balance is possible, but can be steady or unstable (having warmed up from below), and balance is impossible (having warmed up sideways). Thus a lot of cells the structure of a current typical for reley-benar convection mechanism, is replaced global lifting to lower by structure. This change of structures is a consequence of convective interaction and has hysteresis character: the current and heat exchange in one of directions doesn't coincide with heat exchange in the opposite direction. Despite a considerable quantity of works on inclined layers, data on a hysteresis at various relations of a layer aren't numerous.

In the given work parametrical researches of a convection and heat exchange in an inclined layer without the assumption of periodic structure along a layer that allows investigating influence of the relation of the parties of a layer proceed. The basic attention is given to definition of influence of the relation of the parties of a layer, including construction of diagrams of characteristic modes number of Grasgof - the relation of the parties at different angles of slope.

Dependence of an angle of slope at which there is a current reorganization, from number of Prandtl (the corner changed from 0 degrees to 180, then upside-down from 180 to 0 degrees with step 15) is considered. Are received local and averages of Nusselt for various numbers of Prandtl (0,71; 1,74; 7; 13,5; 43,9). The received dependence of number of Nusselt on an angle of slope has appeared is ambiguous. During work two modes were observed: cellular and vortical and as it was observed unstable (saddles) a condition. It is shown that both modes lead to increase thermal stream in comparison with molecular, corresponding to a plane-parallel current. The cellular mode provides much more intensive thermal carrying over, than vortical. As a result transitive character of this phenomenon of hysteresis type which leads close in relation to initial, to structure of a convection and the number of Nusselt different at opposite rotation from the initial is accurately observed.

Calculations received by means of computer laboratory COMGA.

 

O.V.Ryazantseva, A.V.Panteleyev.

(Moscow Aviation Institute, State Technical University, Moscow, Russia).

Global optimization by directed tabu search method.

Currently, widely used met heuristics global optimization methods in solving design problems of space-rocket complexes and the search for optimal control. These methods allow to get close enough to the true result without significant simplifications of mathematical statements of problems and a reasonable time. An example of this method is a Directed Tabu Search method for the global optimization.

The problem is: search of a global extreme of functions of many variables on set of admissible decisions where admissible values of corresponding variables are segments.

In the Directed Tabu Search method involves three phases: Exploration, Diversification and Intensification. On the Exploration phase is the generation of new points near the current solution. Novel concepts of Tabu Search memory elements are introduced to provide anti-cycling rules and applied to escape from local minima. One of the elements of memory - Visited Regions List - is an element of Diversification phase, which is used to organize the search in unvisited areas of study space. It is assumed that one of the best points found in the Exploration and Diversification phase, close to the global minimum. Therefore, the Intensification phase found "good" points are improved in order to produce a result with desired accuracy.

The concept of memory plays a major role in Tabu Search. It is represented by several elements: Tabu List, Tabu Regions, Semi-Tabu Regions and Visited Region List. When implementing the method uses four types of search:

-        exploration neighborhood search;

-        local search;

-        diversification search;

-        intensification search.

In the search strategy is a well-known Nelder-Mead method and Adaptive Pattern Search.

To implement the method formed the software in C++. The functions of the program include:

-        select the function,

-        input parameters for the method,

-        solve the problem and conclusion of the detailed information, including step-by-step,

-        display information about the solution in the text,

-        construction graph,

-        viewing of a detailed protocol of the decision,

-        granting of the help information.

The program interface is represented by a set of tabs, each of which is responsible for the respective functions. Comparing the results obtained using the developed program, the exact solutions proves the effectiveness of Directed Tabu Search for this class of problems. The program realization of method can be useful in the course of training as demonstration of work of global extreme search algorithm.

 

P.A.Panteleev, A.G.Badalova.

(Moscow Aviation Institute, State Technical University, Moscow, Russia).

Methods for determining the type of crisis in the adaptive system of strategic risk management for enterprises of aviation-industrial complex.

Need for a transition to an innovative type of economy in the Russian Federation stipulate an objective need for the development in Russia market risk management services and the creation of infrastructure risk management, allowing reducing the level of risk ness of the business atmosphere. One of the priorities and underlying problems here is the modeling and methodological tools of strategic risk management. Under the strategic risk management is the process of risk management of industrial enterprise, based on the implementation of the chosen strategy of development and achievement of the targets of strategic indicators of the enterprise.

We propose a functional diagram of a system of risk management of aviation-industrial complex (AIC), which specializes in the development of new types of aircraft, which is a system with four feedbacks corresponding to the four horizons of management. In the proposed scheme, developed in accordance with the basic management principles: continuity, focus, system, integration, structured targets for risk management on the horizon control, in accordance with the value management approach. In each of the control loops to develop an appropriate strategy and risk management techniques necessary to determine the risk level by analyzing the financial performance of the company. If in the process of risk management system there is a situation in which, despite the use of different methods of blocking the risks of possible risks, and realized a number of business units the company reached the crisis, the system of strategic risk management needs to be supplemented by new feedbacks reflecting the effect of adaptation to emerging new situations. In this current problem is to find the type of crisis (local, comprehensive, global) and the development of appropriate management decisions. A local crisis usually covers one functional business unit, a comprehensive crisis - more than one. Global Crisis covers the whole enterprise as a whole. The reasons for escalation of realized risks in crises are: a sharp increase in the level of risk, and increase the number of realized risks the emergence of new external factors.

To solve the problem of determining the level of risk and the type of crisis, the apparatus used fuzzy systems. An algorithm for forming fuzzy system, which is used to find the type of crisis on the scale on the basis of linguistic values of the percent crisis-ridden business units and the total number of realized risks. Operation algorithm of fuzzy system contains: fuzzification (input crisp variables are converted into fuzzy), the application of fuzzy inference mechanism (from the base of fuzzy inference rules linking the input fuzzy variables (background) with the output of fuzzy variables (conclusions) are selected so-called active rules applicable to this situation. The result of fuzzy inference mechanism is not clear conclusion); defuzzification (fuzzy conclusion is converted into clear. In this case, the goal is to find the type of crisis with respect to a given scale). Setting the fuzzy expert system holds that changes: the number of linguistic values of input and output variables, the task of universal sets; form of membership functions and their parameters, linguistic inference rules, the method of processing information about the input variables, the method of defuzzification.

In the operation of the proposed fuzzy system it is performed: fuzzification (it is determined the values of all membership functions for each input variable), establishing correspondences (the definition of rules that apply in the current situation) to find output fuzzy set; aggregation; defuzzification. The obtained results allow us to create an effective mathematical tool for the implementation of the methodological foundations of realized risk management, which could escalate into crises.

 

P.A.Fomkin, А.А.Ermakov, L.B.Stroganova.

(Moscow Aviation Institute, State Technical University, Moscow, Russia).

Technical aspects of the study of microbiological samples in a hermetically closed volume.

One of the most important operating conditions for the manned spacecraft is their ecological safety, which includes the guarantee of reliable control besides the physical, chemical and biological parameters of living environment, including above the microbiological factor.

With the realization of the manned interplanetary expeditions, including the autonomous vital activity of crew in flight down Mars, in connection with the absence of the possibility of the sending taken samples to the earth for the analysis, the system of measures and methods of guaranteeing of monitoring and control besides the state of microbiological situation on board the spacecraft must ensure possibility of conducting the necessary studies and processing the obtained results directly as far as crew members on board the automatic spacecraft.

First priority task on the method of solution of this problem - these are selection and the study of the microbiological tests, undertaken based on the elements of interior and equipment of spacecraft. For these purposes in 2007-2008 the Research Institute of space instrument manufacture together with SRF of RF - IMBP RAN [Russian Academy of Science] developed the device of the rapid diagnosis of the composition of micro flora. Into the composition of device enters the thermostat and Petri dishes with nutrient media for the cultivation of microorganisms. Were carried out the preliminary laboratory tests, in course of which was revealed the number of the essential deficiencies, which did not make it possible to use a device on board the automatic spacecraft. Given shortages were removed, and device past successful approval in the course of biological experiment on the base of ground-based experimental complex "MARS-105".

Besides the selection of microbiological tests it was necessary to create the modified mathematical model of pattern recognition of microorganisms, called with the aid of the computational means to conduct the identification of bacteria discovered in the course of flight and fungi. The principle of pattern recognition was for this purpose investigated and the logic circuit of the construction of the mathematical model interesting us was comprised.

Still much work is in prospect, but solution of the problems before the complex mentioned above will compulsorily bring us down the stated goal, but the proposed approaches can find wide application not only before the space branch, but also before clinical medicine.

 

P.V.Shevchenko, A.A.Puntus.

(Moscow Aviation Institute, State Technical University, Moscow, Russia).

Mathematical model of movement of the space vehicle of distant sounding of the Earth concerning its centre of masses.

The purpose of the given research work is working out of incorporated mathematical model of movement of the space vehicle intended for security of engineering processes of planning of distant sounding of the Earth, considering as movement of the centre of masses of the space vehicle on an orbit, and movement of the space vehicle concerning the centre of masses taking into account the set technical requirements on its attitudes. The given incorporated model is developed on the basis of mathematical model of movement of the centre of masses of the space vehicle existing at present, described system of differential equations in a rectangular Greenwich frame and considering influence on orbital flight of the space vehicle of such revolting forces, as a field of forces of an attraction of the Earth together with their anomalies and forces of resistance to movement of the space vehicle by atmosphere of the Earth. Originally the mathematical model of movement of the space vehicle concerning its centre of the masses, considering the restrictions superimposed on an absolute angular velocity, absolute angular acceleration and boundary conditions of position of the space vehicle from an instant of a start of motion by final time is developed. This model is described by system of differential equations of movement by the rectangular frame connected with the space vehicle. Research of mathematical model of movement concerning the centre of masses is based on use of the theorem of Euler about final turn of a rigid body. Space vehicle movement is considered as rotation in one plane concerning some axis with the subsequent passage to three-dimensional movement. Thus function of an angle of rotation is approximated by a spline of the seventh order. Further, sufficient the algorithm of definition of the minimum interval of time of a route of distant sounding is developed for preparation for entrance in connection between the space vehicle and the companion-repeater. Time interval will be considered sufficient if values of parameters of an attitude on this interval satisfy to the set boundary conditions and the restrictions superimposed on an absolute angular velocity and absolute angular acceleration. Then the special software which on the basis of the developed mathematical model and a gang of the initial data allows defining the minimum interval of time, sufficient for preparation for entrance in connection with the companion-repeater is developed. Following magnitudes are defined also: co-ordinates of position of the centre of masses of the space vehicle and a component of its vector of a velocity in the Greenwich and absolute frames. Further there are angles of orientation of the space vehicle in an orbital frame - pitch, roll, yaw; an absolute angular velocity and absolute angular acceleration; projections of an absolute angular velocity, absolute angular acceleration and a modification of absolute angular acceleration; components of a quaternion of orientation of the frame connected with the space vehicle in an absolute frame, the Greenwich true sidereal time; the component of a matrix of the rotation setting orientation of a frame connected with the space vehicle in an absolute frame.

Outcome of work is working out of the special software which, on the basis of the developed mathematical model and a gang of the initial data, ensures calculation of the prognosis of parameters orbital and a space vehicle attitude. As a result the prognosis of position of the centre of masses of the space vehicle and components of a vector of a velocity in the Greenwich and absolute frame, and also angles of orientation of the space vehicle in an orbital frame is received.

Outcomes of the given research work are offered to be used by working out of the special software of complexes of program means of the automated planning of distant sounding of the Earth. Given results can be used in onboard complexes of control by engineering processes of planning of distant sounding of the Earth, and also in onboard complexes and time schedule controls an attitude of the space vehicle concerning its centre of masses.

 

S.V. Ivanov, A.V. Naumov.

(Moscow Aviation Institute, State Technical University, Moscow, Russia).

An algorithm for solving a linear discrete stochastic programming problem with the quantile criteria.

We consider a linear stochastic programming problem with the quantile criteria in the case when random parameters vector has a discrete distribution with a finite number of realizations. Sufficient conditions for the existence of a solution are considered.

To solve the problem we use the confidence method [1]. The idea of this method is to approximate the original quantile optimization problem by a deterministic minimax one. In the equivalent problem the inner problem is to maximize objective function on the selected confidence set of the random parameters realizations, and the external minimum - on optimization strategies. Selection of the optimal confidence set is a challenge problem. In the case of a discrete distribution with a finite number of realizations we can propose an algorithm for solving the problem based on exhaustive search of confidence sets. But in the case of a large number of random parameters vector realizations, the algorithm resulted in significant computational difficulties.

We propose a method for reducing the original problem to a mixed linear programming problem of large dimension. The variables of this problem are divided into two types: the variables of the original problem, which correspond to the appropriate optimization strategy, and the variables of binary type, corresponding to the vertices confidence set. To solve this problem we apply Benders decomposition method [2]. Using this method the resulting problem of large dimension is reduced into multiple subproblems with smaller dimensions. To find an optimal solution we add some new constraints  to subproblems at each iteration of the algorithm. The structure of new constraints allow significantly reduce the dimension of subproblems. Furthermore, we give a way to determine the optimal values ​​of the  binary variables before applying the decomposition method. This way is based on the well known theorem [1] about the form of the optimal confidence set.

We estimate the complexity of the algorithm. Proposed algorithm has exponential complexity as the algorithm based on on exhaustive search of confidence sets, but the results of numerical experiments show that in practice the number of iterations is much smaller than their estimate, so using the proposed algorithm we can find the optimal solution significantly faster than using  exhaustive search of  confidence sets.

1.           I.F.Kibzun, Yu.S.Kan. Stochastic Programming Problems whith the Probobilty Criterias. Moscow. FIZMATLIT, 2009.

2.           Alexander Schrijver. Theory of Linear and Integer Programming. John Wiley & Sons, 1998.

S.D.Makhijanova, A.A.Puntus.

(Moscow Aviation Institute, State Technical University, Moscow, Russia).

About limit cycles in the double oscillator, raised by a nonlinear friction.

In the presented research work mathematical modelling of a two-mass oscillator with a piecewise-nonlinear dry friction is spent and research of corresponding model is conducted, and also problems of modelling of phase portraits of a two-mass oscillator on the personal computer are considered. The method of research of considered mathematical model consists in an analytical solution of the autonomous system of differential equations received as a result of modelling, modelling of the given system on the computer further is spent, the choice of a corresponding numerical method is spent, the program of calculation with use of computer facilities is made and then program calculation on the computer is realized. As a result corresponding phase portraits are modelled on the computer. The autonomous system of differential equations - a special case of system of differential equations when to explanatory variables of such system time is systems, however in this case the given explanatory variable is not included evidently into the functions setting system. We will notice that self-oscillatory systems are named autonomous systems in which periodic oscillations can be realized, and energy losses continuously replenish with inflow of energy from a radiant which is not possessing characteristic oscillating properties. Auto-oscillations thus are such undamped oscillations, an aspect and which properties do not depend on entry conditions and are defined only by properties of system, and energy losses replenish with inflow of energy from a radiant which is not possessing characteristic oscillating properties. The phase portrait of auto-oscillations is a graphic representation of system on a phase plane (or in many-dimensional space) on which co-ordinate axes values of magnitudes of variables of system are put aside. Each point of a phase plane reflects one condition of system and is called as phase, representing or a representative point. The modification of a condition of system is mapped on a phase plane by movement of this point. The track from movement of a representing point is called as a phase trajectory. As a limit cycle is called the isolated closed phase trajectory. The term "isolated" means that in enough small ring-shaped neighborhood of this trajectory there are no other closed phase trajectories. It distinguishes limit cycles from the closed phase trajectories corresponding, for example, to periodic oscillations round a singular point of type the centre.

In the course of performance of the given scientific work the mathematical model of a two-mass oscillator with a piecewise-nonlinear dry friction has been constructed, the analytical solution of the equations in two areas is reduced. Analytical and numerical modelling of the given system on the computer is considered, corresponding phase portraits are received as a result of the given research. Limit cycles we will receive by the following technique. On pressing of button "Start" of the program the algorithm of a solution on the introduced temporary gap is fulfilled. After its end final values of variables are noted in fields of entry conditions, and at following start of algorithm are used as entry conditions. So that to receive a limit cycle, it is necessary to fulfill algorithm while the picture on phase planes will not cease to vary.

So, in the given research work the analytical solution received as a result of mathematical modelling of a two-mass oscillator of autonomous system of differential equations is passed. Besides, in the given research work the method of research of considered mathematical model of a double oscillator and as a result applications of this method construction of limit cycles in such double oscillator raised by a nonlinear friction is fulfilled is presented. For task in view realization, construction and research of considered limit cycles is fulfilled, modelling of the given system on the personal computer is spent, the choice of a corresponding numerical method is realized, the necessary program of calculation is made, calculation on the computer is realized and phase portraits of a two-mass oscillator corresponding to various entry conditions and in various considered areas of a phase plane are received.

 

Y.O.Khan, A.A.Puntus, A.I.Fedyushkin.

(Moscow Aviation Institute, State Technical University, Moscow, Russia).

Mathematical modeling of natural convection in normal and reduced gravity.

Distinguish convection of two types: gravity and non-gravitational type. Consider the natural convection. This work is devoted to solving the test problem of natural convection in a square cavity, heated from the side. The aim is to construct a mathematical model to calculate the thermal, concentration and termo-concentration convection in dimensionless variables at different Raleigh numbers.

We consider the problem of thermal and concentration convection of a viscous incompressible fluid in a square closed area with a thermally insulated horizontal walls and a set temperature at the boundary of vertical walls. A mathematical model of this problem is a two-dimensional Navier-Stokes equations in dimensionless variables in the Boussinesq approximation. To speed on all the boundaries we impose the condition of attachment, but to put such conditions of temperature: the lower and upper horizontal boundaries - insulated (adiabatic) and the left and right vertical boundaries - isothermal. As the initial conditions given by the stationary liquid with a linear heat-conduction temperature distribution.

This problem of natural convection in a square domain was solved in dimensional primitive variables velocity-pressure-temperature. To simulate the considered convection problem, we used the dimensionless equations, data recording, which includes the dimensionless parameters - the Prandtl number (characterizes the ratio of kinematical viscosity and thermal), as well as the Raleigh number. Used a system of Navier-Stokes equations in Boussinesq approximation. Calculations were made using modern hydrodynamic programs.

The calculation results were compared with the "reference" solution, obtained by extrapolation of the numerical solutions on different grids on the grid with zero pitch. The calculation results also showed that under given boundary and initial conditions with increasing Raleigh number the maximum speed module further moves to the boundaries of the area, and the isotherms tend to assume a horizontal position. Comparing the results with the "reference" solution for different Raleigh numbers showed good accuracy of calculations.

Concentration determined by the thermal convection model Raleigh number and Schmidt number. Field concentration under the influence of convection is starting to change with the smaller Raleigh numbers than the temperature field, since the Schmidt number greater than the Prandtl number. Prandtl number is small, i.e. diffusivity is much greater than the viscosity, so that the temperature field under the action of the liquid begins to change only when a sufficiently large Raleigh number (over 100). And when the temperature field unchanged, the concentration field has markedly changed. Concentration field begins to change even when the Raleigh number is 10.

The result is that the concentration heterogeneity under normal conditions is less than in conditions of reduced gravity.

Under the joint action of thermal and concentration convection first suppresses the action of the second at high Raleigh numbers.

As a result of this work, the dependence of thermal and concentration convection, the effect of Raleigh number and the influence of changes in Prandtl number and Schmidt on the motion of fluid in a closed volume.

 

 

 

Artur Agafonovich Puntus, Professor of department of differential equations of the Moscow Aviation Institute (State Technical University). An area of scientific researches is the qualitative theory and applied problems of the differential equations, problems of teaching of courses of higher mathematics, problems of preparation of qualified professionals.



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