Вдосконалення бортової системи контролю вібрації авіаційного газотурбінного двигуна на основі багаторівневої обробки вібраційних сигналів

The article deals with the problem of synthesizing the system of the optimal control of transient modes of a through-type induction heater. An algorithm to control the inductor power is obtained for the case of varying the performance of the technological complex. It is shown that the optimal algorithm for the transient mode has the form of a periodic decaying piecewise continuous function of time with discontinuities of the first kind. The number of intervals of continuity is infinite. It is noted that under conditions of random noise and a wide variety of process parameters, the synthesis of a closed-loop optimal system with temperature feedback seems to be the most appropriate. A specific feature of optimal control algorithms for non-stationary modes is the most using “special” control intervals. The conditions of absolute equality between the current value of the metal temperature at the exit from the heater and the given value are satisfied on “special” intervals of the trajectory. In this case, the temperature of the metal at the exit from the heater remains constant during the all transient modes. Therefore, the synthesis of closed-loop systems with feedback on the metal temperature at the exit from the heater is, in principle, impossible. At the same time, the metal temperature inside the heater varies according to certain regularity in accordance with the optimal algorithm. This established behavior allows us to synthesize a closed-loop system on the “special” interval of optimal control as a system with feedback on temperature at some “internal” point of the heater. Analyzing the nature of the metal temperature distribution along the length of the heater in a transient mode allows to determine the coordinate of the internal point at which the temperature changes with a maximum deviation from the steady-state value. This coordinate is used to set the feedback sensor. A relationship has been established between the temperature change at the control point and the heater power on the “special” interval of the trajectory. On the plane of system parameters “inductor power – temperature at the control point”, the phase trajectory of the closed-loop optimal system on the “special” control interval is plotted. It is shown that the phase trajectory has the form of a piecewise continuous function converging to a new steady-state value. The analysis of the dependence “inductor power – temperature at the control point” shows that the feedback changes sign and gain twice within each interval of continuity. The angular coefficients and initial conditions of the optimal control switching line, the angular coefficients of the linear intervals of phase trajectory, and the sign of feedback within each control continuity interval are determined.

Accurate control of the in-cylinder air/fuel ratio level is critical for both fuel saving and harmful emission reduction of an internal combustion engine. The fuel injection quantity is easy to control with today's electronically controlled fuel injection system, the difficulty is how to accurately determine the fresh charge mass trapped in-cylinder at the end of the gas exchange process, especially for transient operation mode of a vehicle when the throttle position, intake air pressure and engine speed are instantaneously changing. No physical airflow meter exists which has satisfactory response time and measurement accuracy. Described in this paper is a renovated air flow measurement technology combining fast response sensors with 1-dimensional pressure wave action simulation. Utilizing two dynamic pressure transducers(2P) to measure pressure fluctuation near the intake and exhaust ports and coupling the measured pressure signals into the numerical solver of a 1-dimensional gas exchange simulation software, together with the instant flow area at valve locations, the instantaneous gas mass flow rate through the engine intake and exhaust ports can be calculated. The fresh mass and un-swept burnt mass fraction trapped in the cylinder could also be traced along the entire gas exchange process. The response time and model accuracy of this synthetic virtual airflow meter technology is validated against GT-Power model and experiment tests, for both steady-state and transient operating modes.

The paper is dedicated to describing a method for increasing the reliability and survivability of on-board control systems. The object of the research is a class of aircraft — cruise missiles, which are considered one of the most promising weapon systems. The article analyzes modern structures of on-board control systems that ensure high reliability of such systems. The study focuses on analyzing four-channel fault-tolerant systems for on-board control complexes with enhanced survivability, which ensure high operational reliability of the complexes over extend-ed periods without physical maintenance while maintaining resistance to equipment malfunc-tions and failures. Additionally, the paper examines its prototype — a three-channel system with synchronization outputs. Both positive and negative aspects of these systems are highlight-ed, noting their high level of hardware redundancy. For short-lifespan aircraft, such as cruise missiles and similar systems, the authors propose a two-channel quasi-bridge structure (QBS) for the on-board control system, featuring block-level redundancy and reconfiguration. In gen-eral, the QBS represents a system consisting of a sequential connection of redundant nodes with equal reliability. When one of the functional subunits of a redundant node fails, the control and reconfiguration scheme excludes it from the computational process and reconfigures the system structure in a non-stop mode. As a tool for studying the reliability of the on-board system, a probabilistic-physical method (PP-method) has been used, which is based on a diffusive distri-bution of time-to-failure (DN-distribution), specifically formalized for the assessment and pre-diction of the reliability of electronic, electrical, and electromechanical elements and systems. While maintaining the level of redundancy characteristic of all two-channel structures, the pro-posed two-channel redundant QBS, with its decomposition of channels into equally reliable re-dundant nodes, leads to an increase in the probability of failure-free operation (the R-effect), which becomes more significant as the number of nodes increases. The paper also describes the principle of placing functional subunits of the QBS, providing an additional effect — the over-all increase in system survivability.

A control strategy, referred to as open-loop predictive ride-through control, is presented and characterized for several transient operation modes. It is shown that it is possible to bring a three-phase rectifier system from a given initial-state to the desired steady-state in the minimum possible time. This provides the system with inherent ride-through capability, and thus eliminates the need for an uninterruptible power supply, if short-term line disturbances are a problem. Experimental data are given to verify the findings.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

This article is devoted to designing an information management system for the conveyor line of mining enterprises. The analytical design method for the transient mode of the stepped speed control system of the conveyor line was developed. The partial differential equation was used in constructing the conveyor line model. The description of the production system is fulfilled in the single step approximation. A decision was obtained which determines the state of the parameters of the production line for a technological position specified as a function of time. Has been determined the length of the transition period during which the initial condition for the distribution of labor objects along the conveyor affects the parameters of the state of the conveyor line. The method for calculating the current parameters of a conveyor line with the use of partial differential equations allows the design of control systems for production lines of conveyor type for transient modes. The originality of the results obtained is to improve the PDE-models of the conveyor-type production systems used to design highly efficient production control systems operating in transient modes.

The majority of testing cycles for the vehicle comparison is the long-term cycles and could not be used for the short-term transient mode imitations. Also, all the used nowadays testing cycles were designed for internal combustion engine vehicles and take into account not only energy and mechanical aspects, but also pollution and internal combustion engine characteristics. The paper presents a collection of sample signals developed to explore and simulate multiple system impacts to emulate different reference and load conditions. The study describes the major driving modes, such as the constant-speed cruising, speeding up and braking, typical parking regimes, uphill and downhill motion, and taking a turn. The developed testing equipment and software are described. Responses of the battery vehicle drives to the changeable controls and disturbances were studied in the laboratory test bench. The set of test cycles prepared in the frame of the ABB control arrangement was applied to the system evaluation and assessment. The developed methodology can be recommended to adjust the electric drives for different kinds of testing equipment. Experimental validation of the described approach has demonstrated the broad possibilities for the steady-state and transient modes of vehicle quality evaluation. It suits for recommendations that can be made with regard to the tuning of the drive regulators, control looping, sensor allocation, and feedback arrangements.

Piezoelectric modelling using a time domain finite element program

The federal test procedure for vehicle emissions measurement treats the first 505 sec of engine operation as the transient mode. Using this definition as the basis, a special technique was developed and used to trace the elapsed time of vehicles from trip origins during the traffic assignment of zone-to-zone trips on a highway network and to determine the proportions of transient and stabilized operating modes on every link of the network. The travel models of the Sacramento (California) urban area were used to apply this technique and derive operating mode fractions for this urban area. The data from the Nationwide Personal Transportation Survey were used to distinguish between cold transient and hot transient modes. The operating mode fractions were stratified by functional class of roadways and the location within the urban area. The time of day of travel also was used for further stratification. The results show wide variations in the operating mode fractions among the different categories of roadway, location, and time of day.

A brief description of the design concept, structure and performance of the onboard control system (AOCS) of the “Navigator” satellite platform, on the basis of which the spacecraft “Electro-L’ and “Spektr-R” are designed, is presented. The test-flight results of the AOCS attitude accuracy are given. Approaches to the further development of the onboard control equipment for advanced spacecraft are determined and presented.

Electrical energy losses increase in modern grids. The losses are connected with an increase in consumption. Existing models of electric power losses estimation considering climatic factors do not allow estimating the cable temperature in real time. Considering weather and mode factors in real time allows to meet effectively and safely the consumer’s needs to minimize energy losses during transmission, to use electric power equipment effectively. These factors increase an interest in the evaluation of the dynamic thermal mode of overhead transmission lines conductors. The article discusses an approximate analytic solution of the heat balance equation in the transient operation mode of overhead lines based on the least squares method. The accuracy of the results obtained is comparable with the results of solving the heat balance equation of transient thermal mode with the Runge-Kutt method. The analysis of mode and climatic factors effect on the cable temperature in a dynamic thermal mode is presented. The calculation of the maximum permissible current for variation of weather conditions is made. The average electric energy losses during the transient process are calculated with the change of wind, air temperature and solar radiation. The parameters having the greatest effect on the transmission capacity are identified.

The paper is dedicated to the overview of the autonomous ship onboard control system functionality. The paper is dedicated to autonomous maritime navigation, i.e. to planning a safe and optimal route for an autonomous ship amid the absence of crew on board and to handling an autonomous ship when underway, ensuring seaworthiness and route correctness. Moreover, the paper describes communications of several autonomous ships and autonomous and ordinary ships to infer a collective decision on how to pass safely through a particular area. Since it is expected that autonomous ships are going to be equipped with dozens of sensors and detectors, the paper describes remote monitoring of an autonomous ship when underway. Since an autonomous ship highly depends on its onboard control system, the paper also pays attention to the robustness of the system. The paper suggests evolutionary computations as a solution for the route planning problem because this approach enables to perform multicriteria optimization of a set of solutions simultaneously. For autonomous ship handling and seaworthiness control, the paper suggests machine learning techniques because these techniques can solve problems in case of uncertainty and the environmental mutability. For inter-ship communications, the paper suggests distributed consensus algorithms, widely used in parallel and distributed computation systems. To ensure the onboard control system robustness, the paper suggests the actor approach that represents that the entire software system consists of a set of elementary agents communicating in the distributed computational environment.

This paper conceptualizes the main principles of comprehensive software verification for an onboard spacecraft control system. An optimal comprehensive verification strategy for onboard softwareis selected by rigorously stating and solving the corresponding optimization problem. Software verification methods with functional correctness indicators are proposed.

The object of this research is the process of oscillation of liquid metallurgical slag in a slag bowl under the influence of acceleration. The work considers the oscillation processes in bowls used on railway and road slug cars, which differ in design and operating conditions. One of the key problems associated with the transportation of liquid slag is the dynamic instability of the melt, which leads to oscillations and splashing, which can pose a safety threat and reduce the efficiency of the transportation process. In this regard, the study of the dynamics of liquid slag in bowls of various designs is an urgent task aimed at optimizing transportation parameters and developing measures to reduce the risk of slag splashing. Based on the results of numerical modeling, it was established that the nature of the oscillations of liquid slag in the bowl significantly depends on the magnitude of the acceleration, the type of slag and the design of the bowl. In particular, the acceleration ranges at which different oscillation modes are observed, from minor surface disturbances to intensive slag splashing, have been determined. At the same time, the differences in the nature of oscillations for different types of slag and bowl designs lie within the limits determined by their physicochemical properties and geometric parameters. The results obtained allow to conclude that it is possible to develop measures for the operation of slag bowls, as well as their designs, in the direction of reducing the amplitude of liquid slag oscillations, which, in turn, contributes to increasing transportation safety and reducing dynamic loads on the bowl walls. The obtained data can be used in the design of new bowl designs to optimize their shape and internal elements in order to minimize slag oscillations. In addition, the information provided can be useful for metallurgical enterprises to develop effective methods for controlling and monitoring slag stability during transportation.

Several methods for diagnosing rolling equipment in transient operating modes are presented, primarily when the strip is captured by the rolls and indicators - the time of delay in the reaction of sections, correlation fields, and the oscillation period. The directions of development and search for new methods are considered, examples of using the features of rolling and equipment operation for diagnostic purposes are given.

Advanced pressurized water reactors are the main part of a new generation of nuclear power plant projects under development that provide cost-effective power production for various needs (Yemelyanov et al. 1982, Klimov 2002, Boyko et al. 2005, Baklushin 2011, Bays et al. 2019, Nuclear Technology Review 2019). The innovative technologies are aimed at improving the safety and reliability as well as at reducing the cost of NPPs. At the same time, improvements in design, technological and layout solutions are focused primarily on the reactor core. Assessments of the efficiency of these improvements are preceded by numerical simulations of the processes in the core, in particular heat generation and sink, with account for the difference between the study object and the standard version tested in operational practice. The authors of the article propose a method for calculating the temperature field in the core of a heterogeneous reactor (using the example of a pressurized water reactor), which makes it possible to quickly assess the level of temperature safety of various changes in the core and has the necessary speed for analyzing transients in real time. This method is based on the energy equation for an equivalent homogeneous core in the form of a heat equation that takes into account the main features of the simulated heterogeneous structure. The procedure for recovering the temperature field of a heterogeneous reactor uses the analytical relation obtained in this work for the heat sink function, taking into account inter-fuel element heat leakage losses. Calculations of temperature fields in the model of the PWR type reactor (The Westinghouse Pressurized Water Reactor Nuclear Plant 1984) were carried out in stationary and transient operating modes. The calculation results were compared with the results of CFD simulation. The area of competing use of the temperature field recovery method was indicated.