Vol 57, No 3 (2018)

A mathematical model of the one-dimensional controlled motion of a hybrid vibrational system is proposed. The plant includes an inhomogeneous elastic rod with loads concentrated at its endpoints. An analytical-numerical procedure for finding the eigenvalues (eigenfrequencies) and eigenfunctions is developed. A novel procedure to take into account the nonuniform distributed forces and forces concentrated at the endpoints using a modification of Grinberg’s approach is presented. Efficient statements and constructive approximate solutions of the problems for controlling the motion of a countably dimensional vibrational system with a complex distribution of eigenfrequencies are proposed.

We propose an identification method for the aerodynamic coefficients of the lift force, drag force, and pitch moment in the supercritical range of angles of attack. The investigated models take into account the hysteresis with respect to the angle of attack, which is the main specific feature of aerodynamic coefficients in the specified range. Also, we consider the problem to find and correct errors of onboard measurements in the channels of the angle of attack and the air speed and the computational model for the forces and moments created by engines with a deflected thrust vector. We provide processing examples for the flight test data obtained during maneuvers on supercritical angles of attack; they confirm the efficiency of the proposed methods.

Limiting performance analysis is performed for isolation of an object on a movable base from short-duration impact excitations by means of an active shock isolator with anticipating control. The external disturbance (excitation) is modeled by the time history of the absolute acceleration of the base. The control is performed by a force that acts between the base and the object to be protected. The absolute value of the control force is subject to a constraint. A procedure is proposed for constructing optimal anticipating controls that minimize the peak magnitude of the displacement of the object relative to the base for external disturbances from a certain class. For a number of types of external disturbances, the solution of the optimal control problem is obtained in closed form. The controls that are constructed in closed form are modified to be applicable for the disturbances for which closedform solutions are absent.

In recent years, the widespread TCP/IP computer network model has been replaced by the software-defined network model, where the control plane is separated from the data plane and is logically centralized. The new model requires a revision of traditional network control protocols. One group of such revised protocols consists of multicast routing protocols. In this paper, the multicast routing protocols used in traditional TCP/IP networks are analyzed, and their basic disadvantages and difficulties in their application in software-defined networks are revealed. Multicast routing algorithms that use the capabilities of software-defined networks and ensure the optimization and reliability of routes in multicast routing are described. These algorithms are exempt from the drawbacks of traditional networks. The proposed algorithms are implemented as an application for the RunOS controller. This experimental study shows that the delays due to the use of the proposed algorithms for restructuring routes satisfy the requirements of telecommunications operators of large regional networks.

A problem of optimizing a matrix sparse in the joint Frobenius-Schatten norm is considered. The least rows are proposed to be truncated according to the lower bound to fight the ill-conditionality of the matrix. Truncation not only helps avoid incorrect termination of the algorithm but it also reduces the computational complexity. Convergence analysis ensures that a truncation algorithm finds an approximate solution to the problem. The numerical experiments show the advantage of the truncation method over the previous algorithm.

This paper studies a vehicle routing problem with synchronization constraints and time windows. In this problem, a subset of nodes requires more than one vehicle to satisfy its demand simultaneously. We propose three new mixed integer linear formulations for this problem and we evaluate their efficiency over a large set of instances taken from the literature. The computational results reveal that the proposed linear formulations allow solving larger instances in a shorter computational time than the ones previously proposed in the literature.

The work is devoted to the development of methods of inference (that are used in logicaltype production systems) based on the fuzzy degree of truth for the most commonly used fuzzy implications. For the block of rules at the stage of defuzzification, the discrete version of the method of the center of gravity is applied. The inference of an output value is considered for two cases: where the membership functions of consequents of rules intersect and where these functions are disjoint. The second case also includes models of the singleton type. For both cases, the relations of computing the clear output of the block of system rules are derived; they reduce the computational complexity to the polynomial complexity.

A mathematical model is proposed for representing a multisatellite constellation as a tree graph for the purpose of maintaining its formation. The method of correction of the satellite constellation with transversal impulses using the classical linear-quadratic control is developed. The results of the long-term modeling of a satellite constellation (SC) of four spacecraft for different variants representing its formation as a graph are presented. Questions on the stability of the control laws and accuracy of maintaining the fformation are discussed; the necessary expenses of the characteristic velocity of the corrective impulses are listed. The choice of the control-law parameters reflects a compromise between the accuracy of maintaining the formation and the required fuel consumption. The method allows taking into account an additional requirement, which is typical for highly elliptical orbits: the restriction of the minimum altitude of the perigee. The modeling of the constellations involved using a highly accurate model to predict the spacecraft’s motion, which takes into account the noncentrality of the Earth’s gravitational field, the gravity of the Moon and Sun, and the pressure of solar radiation.