An approach to the structural identifiability analysis of nonlinear dynamic systems under uncertainty is proposed. We have shown that S-synchronization is the necessary condition for the structural identifiability of a nonlinear system. Conditions are obtained for the design of a model which identifies the nonlinear part of the system. The method is proposed for the obtaining of a set which contains the information on the nonlinear part. A class of geometric frameworks which reflect the state of the system nonlinear part is introduced. Geometrical frameworks are defined on the synthesized set. The conditions are given for the structural indistinguishability of geometric frameworks on the set of S-synchronizing inputs. Local identifiability conditions are obtained for the nonlinear part. We are shown that a non-synchronizing input gives an insignificant geometric framework. This leads to a structural non-identifiability of the system nonlinear part. The method is proposed for the estimation of the structural identifiability the nonlinear part of the system. Conditions for parametric identifiability of the system linear part are obtained. We show that the structural identifiability is the basis for the structural identification of the system. The hierarchical immersion method is proposed for the estimation of nonlinear system structural parameters. The method is used for the structural identification of a system with Bouc-Wen hysteresis.

This paper presents a proposed new indirect method determining instantly oil well debit using developed mathematical models. As a result integrated analysis using the models it has been revealed correlation between oil well debit and well throw out flow temperature. Therefore putting purpose was obtained. Mathematical models are developed for the distribution of fluid flow temperature along the length of the tubing from the well bottom to the wellhead and along the length of the oil pipeline from the collector of oil wells to the oil treatment unit. On the basis of experimental data, the authors propose formulas in the form of the relationship between oil emulsion (OE) viscosity, the flow temperature and concentration of water globule in OE and the coefficient of heat transfer from the fluid flow in the wellbore (WB) to the rock, and heat capacity and thermal conductivity of gas, water, rock and steel of the WB walls. This effect is demonstrated in the constructed diagrams. It is shown bottom temperature jump as a result of the Joule Thomson drosseling effect then connective transmitted up at flow rate v. In such case well-head or well outlet oil mixture (OM) flow temperature depend more of volume of stream flow than of bottom hole temperature. Thought in the paper, do not taking into consideration great casing annulus areas influence to the well outlet flow temperature. As shown from supporting paper the relative values og the thermal conductivity of the liquid column and gas column present in the casing annulus order less than well bore (WB) wall thermal conductivity. Consequently well outlet OM flow temperature will depends not only of the volume of stream flow, also of the bottom hole temperature and of the gas column and liquid column.

A new method for determining the oil well flow rate by measuring the downstream temperature is developed. A mathematical model is proposed that allows calculating the thermal profile of the fluid along the wellbore for determining the oil well flow rate with account of the geothermal gradient in the rock surrounding the wellbore. It is shown, that unlike the existing methods the new proposed method allows determining the instantaneous discharge of a well very easily. One of the actual challenges in fluid (oil, water and gas) transportation from wells to oil treatment installation is determination of a law of temperature distribution along the length of a pipeline at low ambient temperature. That temperature leads to increase in viscosity and deposition of wax on inner surface of a pipe. To overcome that challenge it is needed to consider several defining characteristics of formation fluid (FF) flow. Complexity of a solution is caused by two factors. From the one hand, in most cases (especially on a late stage of field development) FF is an oil emulsion (OE) that contains gas bubbles. From the other hand, temperature gradient between fluid flow and the environment has significant value (especially in the winter period of the year). At the same time, the higher content of emulsified water droplets (EWD) in OE and lower flow temperature, the higher FF viscosity, and consequently productivity (efficiency) of oil pumping system is reduced. Performed research and analysis of field experimental data showed that a function of oil viscosity versus temperature has a hyperbolic law; a function of OE viscosity versus concentration of EWD has a parabolic one. A heat balance for a certain section of a pipeline in steady state of fluid motion using a method of separation of variables was established taking into account above mentioned factors, Fourier’s empirical laws on heat conductivity and Newton’s law on heat transfer. As a result, unlike existing works, an exponential law of distribution of temperature along the length of a pipeline is obtained. A law takes into account nonlinear nature of change in viscosity of OE from change in temperature of flow and concentration of water in an emulsion. As a result, in contrast to the existing works, the proposed exponential law of temperature distribution along the length of the pipeline is obtained, taking into account the nonlinear nature of variation of OE viscosity with the change in the flow temperature and the concentration of water in the emulsion. The results of the calculation are presented in the form of a table and graphs.

One of the directions of aviation development is solving environmental problems, which excludes the emission of harmful substances into the atmosphere (nitric oxide, carbon monoxide) during the operation of an aircraft gas turbine engine (GTE) [1]. At low temperatures, oxygen and nitrogen are inert gases. At temperatures of 1100... 1600 K, oxides are formed, where nitrogen takes a valence of one to five. At temperatures above 1600 K, their atomic decomposition occurs. At temperatures in the range of 1100—1600 K, a reduction in NOx is possible with good mixing and a sufficient length of the combustion chamber, which determines the burning time of gases. If the combustion process is interrupted due to the poor operation of the automation, either vibro-combustion (atomic decomposition of NOx oxide) occurs at a temperature of 1600 K or flame failure occurs at 1100 K. Improving the process of converting the chemical energy of fuel and converting it into mechanical energy under conditions of uncertainty (variable caloric content of kerosene, changes in environmental parameters, wear of control equipment) is possible using neuro-fuzzy control of aviation gas turbine engine emissions into the environment. The control signal will be the fuel consumption in the diffusion manifold. In this case, fuel consumption in homogeneous reservoirs will vary evenly, provided that the total amount of fuel remains constant for the engine under consideration (the thrust should not change in the mode). A dynamic model of a neuro-fuzzy fuel consumption regulator by a diffusion collector has been developed. The method of obtaining training samples " % GT" = f (MNOx) for constructing the neural part of the regulator is presented. The desired " triangular" region of MNOx location (the integral of emission of nitrogen oxide emissions) is determined, on the basis of which control algorithms " with economy" and " without economy" of the MNOx integral are proposed.

The new path planning method for AUV group moved in the " leader-followers" mode in a desired formation in an unknown environment with obstacles is proposed in paper. In this case one AUV plays role of AUV-leader, which has information about the mission and plans a safe trajectory of its movement, depending on its purpose and detected obstacles. AUV-followers must move behind the leader, in accordance with their assigned place in formation, using information about the current position of the leader, received via acoustic communication channels, and information about their distances to obstacles, detected by their onboard rangefinders. Due to the low bandwidth of acoustic communication channels, there is a problem of matching the position of the AUV-followers during obstacles avoidance. It is necessary to avoid collisions between AUV of group. This problem is solved by means of the preliminary forming for each follower of the only possible trajectory of movement inside formation which will provide it safe movement relatively other followers when this AUVfollower moves around detected obstacle. This approach allows do not coordinate the current position of the AUV-followers relative to other AUV of group if a high-precision control system is used, and as a result it does not require additional data exchange between the AUV group. In this paper, an approach to the forming of AUV-follower trajectories inside AUV formation and the method of forming the desired position of the AUV-followers on these trajectories are proposed. The effectiveness of the proposed method is confirmed by the results of mathematical modeling.

The article is devoted to the development and research of the method of predicting the events on the trajectory of takeoff, climb and overcome highrise obstacles on the course. The prediction method is based on the energy approach to flight control, created by us in previous works. The mathematical formulation of the method is the energy balance equation describing the mutual influence of all acting forces in the aircraft-engine-environment" system. In this article, the equation is extended to ground modes of movement along the runway. For this, a term is added to the equation that takes into account the action of braking forces from the chassis. The balance equation allows us to directly obtain an algorithm for calculating the length of the forward trajectory required for the accumulation of the required amount of terminal energy. Takeoff trajectory includes ground and air segments. Therefore, the possibility of overcoming the obstacle is fixed by the algorithm at the point of a possible decision to takeoff, taking into account the next air segment. This point is reached before the decision-making airspeed prescribed by the flight manual is reached. This advance warning of the possibility of takeoff improves situational awareness of the pilot, which reduces stress and reduces the risk of erroneous actions. A computer stand was developed for the research. Single launches and series of statistical tests are possible. Takeoff scenarios are generated in the stand operator window, as well as initial runway conditions, atmospheric disturbances, aircraft configuration, and obstacle coordinates are specified. The parameters of random errors in the takeoff weight and centering are assigned, as well as the noise of longitudinal overload measurements are set. A large volume of deterministic and statistical tests of algorithms for predicting events on the takeoff trajectory was performed at the stand. Using the statistical analysis module, the characteristics of the range prediction errors to the take-off decision point and the nose wheel separation point were calculated. Probability densities and histograms of error distribution over five characteristic zones of deviations from the mean are constructed. The confidence intervals for calculating the mathematical expectation are obtained. A prototype of an electronic indicator of the takeoff trajectory with marks of predictive characteristic coordinates has been developed.

The article considers the algorithm of rational planning of work on preparing a group of aircraft for departure, provided that the duration of each of the work is random. The work is carried out by specialists of different profiles with restrictions — it is not allowed to simultaneously perform two or more work on one aircraft and the simultaneous work of a specialist on two or more aircraft. To evaluate the preparation plan for a group of aircraft for departure, the following indicators are taken: the time required to complete all work with a given guaranteed probability and the probability of all work being completed within a given time. To conduct a probabilistic analysis of the sequence of events that determine the progress of work, at the first stage a graph of work is built. When constructing the work graph, the restrictions imposed during the statement of the problem are taken into account by introducing fictitious works. At the second stage, on the basis of the constructed graph of work performance, a stochastic model is developed in which the duration of each work is modeled in accordance with a given distribution law. For many implementations, a distribution function of a random variable is constructed — the total time of preparation of a group of aircraft for departure, by which the values of the required performance indicators are determined. Peculiarities of constructing a graph of work performance are analyzed on the example of preparation for the departure of four aircraft. A detailed probabilistic analysis of a rational plan in conditions of uncertainty — with a random duration of work — was carried out on the example of a rational plan of work on a group of two aircraft. As a result of stochastic modeling, the distribution functions of the time moment of the end of each of the work, the delay time of the start of work and the time of the end of all work on the group of aircraft are constructed. Based on the obtained distribution laws, the dependences of the numerical characteristics of random variables — the number of completed work on the aircraft — on the current time were found. The obtained values of the performance indicators allow us to assess the acceptability of the checked rational plan. If, with rational planning of work by a team of a given composition, the guaranteed time to complete work on a group of aircraft is greater than the required value, then the composition of the team will increase. An algorithm has been developed to justify the composition of the minimum number of crews, which can provide training of a group of aircraft with a given reliability for a given time with a random duration of work.