Table of contents

2019 Workshop on Materials and Engineering in Aeronautics (MEA2019) was held 16-17 October 2019 in Moscow Aviation Institute (National Research University).

This Workshop was held 15 times from 2001 to 2018. Each was attended by over 20 participants who submitted their reports for publishing. The participants represented mostly the leading technical universities of Russia. The Scientific Committee hopes that the international involvement would increase.

The (MEA2019) Workshop Proceedings include 28 papers but the scope is actually huge. It covers materials & structure development, aircraft and airships design, pilot interface, aircraft parameter identification, system theory, control, aircraft engines technical state monitoring, robots, statistical classification. This year we include more papers dealing with deep learning and recurrent neural networks applications. In the year 2019 the Scientific Committee's confirms its traditional position not to limit the creativity of the participants. As a result all the papers are unlike one another and many of them contain original ideas and approaches. That is why our advice to a reader is not to judge the Proceedings by one or two papers but look through the most part of them.

On behalf of the Workshop Scientific Committee the scientific editors of MEA2019 Proceedings:

Evgeny V. Nikulchev, Dr., Professor of MIREA – Russian Technological University, nikulchev@mail.ru

Oleg N. Korsun, Dr., Prof., Head of the laboratory, State Research Institute of Aviation Systems, marmottoduo@yandex.ru

All papers published in this volume of IOP Conference Series: Materials Science and Engineering have been peer reviewed through processes administered by the proceedings Editors. Reviews were conducted by expert referees to the professional and scientific standards expected of a proceedings journal published by IOP Publishing.

The cause for imperative programming paradigm shift is the impossibility of developing software systems of a new level of complexity. We consider the evolution of programming paradigms: structured, procedural, and object-oriented. We demonstrate new ways of code duplication reducing have appeared with the shift of paradigm. We conclude the factor of code duplication reducing determines the direction of programming paradigm evolution. We discover the constraints, which were introduced in the paradigms, simplify the development of software systems. We conclude the new constraints allow the development of more complex software systems. The main reason for the code duplication is the low qualification of programmers. Therefore, in the process of learning programming, one should pay attention to code duplication and ways to reduce it.

The description of the model for investigation of the influence of rectangular dimensions in terms of cutouts on the stress-strain state (SSS) in the layers of three-layer conical shells is given. The finite element model is based on the layer-by-layer analysis approach and allows to perform calculations of SSS in shell layers in a wide range of changes in the physical and mechanical characteristics of the layers in the presence of cut-outs. The equations of the classical theory of shells at reception of effective approximations (leading to high speed of convergence of received results) and construction of finite-element model of moment bearing layers are used. The approach with application of the elasticity theory relations for a three-dimensional body in curvilinear coordinates and obtained approximations for construction of a finite element model of the filler layer is described. Influence of the cut-out mortar angle on the parameters of the three-layer shell with load-bearing layers of composite materials is investigated.

The problem of improvement of images, in implementation process of automatic control of the geometrical sizes of the products which are on the conveyer belt is considered. The purpose of work is development of the method of automatic structural and parametrical identification of the combination of algorithms for the solution of the problem of preprocessing of images. Serve as input parameters of the system: the image of the controlled product in the RGB format and the image standard in the bitmap. The algorithm of correction of defects of the image and the subsequent selection of edges is offered adapting to shooting conditions (camera type, its permission and surface illumination). On the output the vector of operators and their parameters forms.

This paper is a part of a series of articles on unified nonparametric methods in dynamic systems theory. Here the authors propose a new method for dynamic system sensor fault real-time detection and localization based only on some past measurements of monitored system input-output signals. The described nonparametric method needs no any priori information on system or sensor model parameters and does not require functional redundancy, identification, prediction, training or statistical calculations. An example of nonparametric detection and localization of aircraft multiple sensor faults is presented.

The possibilities of various configurations of the recurrent neural networks in solving the problems of the maintenance performance based on the multidimensional time series have been investigated. The typical examples of the maintenance performance' problems from technical and medical diagnostics have been considered. The configurations' examples of the one- and two-layer recurrent neural networks with the RNN, LSTM, and GRU neurons for the aircraft engine maintenance problems have been given, the graphical dependencies of the development' results of the neural network models, the estimates of the development time, and the estimates of the accuracy indicator have been presented. The conclusions about the advantages of the recurrent neural networks with the LSTM and GRU neurons have been made.

A quality assurance model is proposed for the design, manufacture, testing of aerospace products based on robust design approaches and the widespread use of additive technologies. Examples of developing proposals and optimizing the design of aerospace engineering products based on the presented are given. Tests of optimized prototypes of products made by selective laser sintering show positive results.

Aircraft composite structure design in the field of production technology is the outlook research trend. New mathematical model relations for the buckling investigation of structurally-anisotropic panels comprising composite materials are presented. The primary scientific novelty is the further development of the theory of thin-walled elastic ribs related to the contact problem for the skin and the rib with an improved rib model. One considers the residual thermal stresses and the preliminary tension of the reinforcing fibers with respect to panel production technology. The buckling problem results in the boundary value problem when solving for the eighth order partial derivative equation in the rectangular field. The solution is designed by a double trigonometric series and by a unitary trigonometric series. The results of testing series are presented.

In this paper, the questions of the existence and calculation of the steady circulating motion of the airship in the horizontal plane are considered.

This paper deals with the design of a test bench for an unnamed aerial vehicle UAV type convertiplane with controlled electric drives and tilt rotors (propellers) executed on a quadcopter pattern. This experimental test bench provides an intermediate step between simulation process and real time flight of the UAV, it allows to test its and evaluate solutions in safe and controllable environment conditions. Thus, the development of methods of state estimation and control UAV becomes possible, in addition the developed system can be used for teaching about the basis of automatic control in multirotor aerial vehicles. The test bench presented in this paper contains a convertiplane type quadcopter attached on the base through a universal joint which let the UAV be able to rotate around plane axes x and y, while the vertical axis z is fixed, in turn this part of the system is fixed through a bar connected with a linear guideway block that moves over a linear guide which depends of the generated lifting force by the UAV. To determinate the travelled road of the system and the different parameters of the behavior of the convertiplane it has been also implemented a measuring system.

The article deals with the assessment of the technical condition of gas turbine engines. The analysis of the application of traditional approaches to the assessment of the technical condition of gas turbine engines. The technique of obtaining parameters of low-frequency torsional vibrations of the shaft on the basis of precision chronometric measurements is presented.

This paper deals with the problem of open-loop control design for a dynamic object which is described by a nonlinear system of differential equations. To solve this problem a direct method is used, in which the target functional is minimized by population-based algorithm. The method is applied to a test problem which consists of finding optimal control for spacial motion of maneuverable aircraft. Proposed technique is compared with two classical solutions to considered problem. One of them is based on equating to zero the partial control derivatives of the Hamilton function, wherease the other on the Hamilton function maximum over controls (Pontryagin maximum principle). The paper confirms high degree of similarity between solutions obtained by all considered methods of selecting target functional. However, classical algotithms show slightly worse accuracy and higher sensitivity to the quality of initial approximation. In addition, proposed direct method permits to evade the necessity to solve a two–point boundary value problem required in classical algorithms.

The paper deals with the problem of operator's state estimating. For this purpose various approaches based on using deep convolutional neural networks are proposed. The approach using automatic emotion recognition methods is considered in the most detail. During the experiment video records of the operator's face registered during operator performing the flight task on the flight simulator were processed. To determine the type of operator's activity the studies based on using the emotional background of the face are also carried out. The experimental results of this approach confirmed the efficiency of the selected methods, especially for monitoring the operator's state when falling asleep.

The problem is considered and the formalized method of integration of the observer and the regulator in the tracking control system of object of rather arbitrary type is offered. The solution of the problem is carried out on the basis of the General principle of isomorphism. Unlike existing methods, the structure of the control loop is not predetermined. The control loop, the regulator and the observer are determined by the structure of the control object and are formed in a uniquely defined way based on the separation theorem.

The paper considers the issues of automatic classification of vibrational states of aircraft engine malfunctions based on the use of convolutional neural network processing of vibrational measurement data presented in spectral form and the knowledge of experts with experience in interpreting spectrograms characterizing the vibrational state of aircraft engines. The developed spectrogram analysis model allows the state monitoring of aircraft engines in automatic mode both during maintenance and in flight operation. The system is able to timely notify technical personnel or crew about the appearance of signs of emergency situations, as well as the type of possible malfunctions. It is shown that the main problem affecting the quality of detection of a potential turbine malfunction is a small sample of data corresponding to malfunctioning states. It is proposed to detect emission anomalies in a small sample by recognizing a modified wavelet transform and neural network clustering, which allows more complete formation of a training sample. The data samples used in training the neural network classifier during the experimental studies were generated on the basis of existing archive files containing complete aperture data from engine vibration sensors and information about malfunctions detected in them.

In modern robotics, there are many approaches to planning the trajectory of the portal manipulator. Methods based on the use of graphs, methods of potential fields, with the use of cellular decomposition, intelligent and others are used. Many varieties are based on similar mathematical apparatus. An important aspect of the trajectory search method applicability is convenience of chosen workspace and obstacles representation method. The approach proposed for manipulator path modelling implies a multi-level process, which includes periodic calculation and updating of invalid configurations set, considering the held cargo dimensions, a neural map creation and activation by the wave front propagation method etc. During experimental simulations with different activation functions, numbers of artificial neurons and synaptic connection implementation types, few methods of neural map activation have been considered, including flat and/or three-dimensional raster methods and wave propagation with static obstacles.

The paper shows that to study the reliability and fault tolerance of air transportation networks, methods of percolation theory can be used, in which any aviation transport structure can be represented as a random non-planar, incompletely connected graph (nodes are airports, arcs are airlines). In the theory of percolation, one can consider the solution of the problems of finding the shares of blocked nodes and blocked connections for networks with various random and regular structures, in which they decompose into unconnected areas. The share of blocked nodes (in the node problem) or connections (in the connection problem), at which the conductivity between two arbitrarily selected network nodes disappears, is called the percolation (flow) threshold. For the same structure, the values of percolation thresholds for the bond problem and the node problem have different meanings. The percolation threshold value depends on the average number of connections per network node (density), and is a criterion for its reliability, i.e. determines the percentage of blocked nodes and/or communications that the network will lose the necessary level of performance ability. The dependence of the blocking threshold (percolation) on the network connection density can be expressed mathematically. Using a map of a real aviation transport network, it is possible to determine the average number of connections per one node and then calculate the threshold value of its predetermined reliability value. If the reliability threshold needs to be increased, then the necessary number of additional links can be calculated.

The paper represents the trial results of nonwoven fabric stencil-screen printed gauge indicators that can be made on other two types of fabric. They can be applied either for specific producing of pilot and test pilots' uniform or for airport emergency and fire officers clothing. The research being carried out, volt-ampere characteristics of conductive belt layer and electrical resistance scale effected by distortion were identified. It was also revealed that aramid fiber fabric sensors were to be applicable for creep stress measurement at temperatures of 20–200 C.

This article assesses the potential increase in the transport and economic characteristics of heavy cargo and passenger aircraft, if they are processed into WIG craft. This type of air transport is of interest from the point of view of improvement of characteristics from the position of mass use on the airways that pass mainly over the water surface of seas and oceans, as 75% of international air transport is accounted for by these airways. Classic amphibious WIG crafts are known to have extremely low performance due to their high aerodynamic resistance, high structural weight and increased fuel consumption in take-off/landing modes. The solution to this problem may be to switch to airfield take-off WIG crafts. As part of the work, boundary conditions for the study were developed, and a set of formulas was developed to allow for a recalculation of fuel and payload redistribution depending on the operating conditions. The results include changes in gross weight, transport and fuel efficiency, as well as potential changes in aircraft operating costs.

The principles of expert system are proposed in the development of software application for calculations of rational takeoff and landing characteristics. The modular architecture is developed for the process of takeoff and landing parameters calculations in the system. A prototype of a client-server software application for electronic flight bag based on tablet computer was developed on the example of a specific type of Russian aircraft.

A post-publication change was made to this article on 21 February 2020 to correct an author name.

Applied design method for cylindrical metal panels with mild camber with possible post-buckling state when compressed is suggested. Method is based on analytical solution of geometrically non-linear task and is reduced to non-linear equation solution in panel thickness when reaching critical stress with post-buckling behaviour.

In this paper, determination of aerodynamic parameters of the aircraft in various conditions of input signal which loses its signal after some times is discussed. Normally distributed random variables are utilized as the measurement noise. The results, which show the accuracy of estimation depending on the condition of input signal, are presented.

The paper proposes to use the research method for chaotic processes based on the identification of weak symmetry breaking of the restored attractor. It is shown how the calculations results can be used to identify systems. An algorithm for creating finite-difference models has been developed, including: calculating by numerical methods the necessary conditions for the existence of chaos, reconstructing an attractor in a time series, searching for symmetric attractor fragments under conditions of weak symmetry breaking, determining the form of nonlinearities, and parametric identification. The result of the algorithm is a system of finite-difference equations in the state space Criteria for assessing symmetry breaking based on estimates of the divergence of fragments of phase trajectories are introduced. The results of modeling systems with chaotic dynamics are presented.

The article considers the problem of estimating wind velocity in flight. The method proposed in this paper provides estimates for three projections of wind velocity in a normal Earth coordinate system using satellite navigation data (SNS), as well as on-board barometric measurements of flight speed. It is assumed that the wind has a constant velocity and direction for the flight interval, the duration of which is 30–31 s. The proposed algorithm can provide measurement of three projections of wind velocity for interval 0.5 s, which compares favourably with other options when the required observation interval was tens of seconds.

The algorithm of separate words automatic recognition based on convolutional neural networks is developed and presented in this paper. Distinctive feature of this algorithm is the training on sets consisting of only hundreds or thousands of samples. Therefore, important problem is the selection of optimal architecture for neural network, which was firstly proposed and tested. After that, four different cases for recognition were researched: speaker-dependent recognition without noise, speaker-independent recognition without noise, speaker-dependent recognition with noise, speaker-independent recognition without noise. Finally, we analyse the experiment results that showed good results for all cases of interest.

A mathematical model of induction heating process of paramagnetic thin-wall shells was considered. Electromagnetic processes in the system "inductor heated shell-temperature equalization devices" are modelled by the method of coupled circuits, thermal processes — by the differential-difference method. The model is implemented in MATLAB and is used to optimize the heating process based on partial criteria that are formulated in fuzzy form.

The paper centres round the problem of the engineering a motion control system for a mobile robot based on the effective selection of software components with respect to the numerical criterion proposed by the authors. The data for the selection process comes out the reproducible experiments with the sets of alternative components in a Gazebo virtual infrastructure simulating the real robot operating conditions. The genetic algorithm is used to reduce the number of experiments with unpromising sets of software components. The methodology proposed by the authors is applied to the real task of engineering a motion control system for a non-anthropomorphic mobile robot. The virtual infrastructure and genetic algorithm parameters are provided as well as the physical model of the robot for that task. To calculate the integral quality criterion proposed in the paper, 4 partial quality criteria were measured in the experiments with different software components. The motion process of the physical robot with the selected software components is shown.

The article considers a mathematical model of lithium-ion battery cell and battery (LIB) on its basis. The developed mathematical model allows predicting LIB temperature on different parts of its surface during charging and discharging by nominal and maximum currents. The results of the battery discharge process simulation and validation of the mathematical model based on the field experiment results are also presented

The basic provisions of the approach to the creation of hybrid angular position sensors, the principle of output signal correction are considered.