A level set method based on the Bayesian risk for medical image segmentation

This paper proposes an alternative criterion derived from the Bayesian risk classification error for image segmentation. The proposed model introduces a region-based force determined through the difference of the posterior image densities for the different classes, a term based on the prior probability derived from Kullback-Leibler information number, and a regularity term adopted to avoid the generation of excessively irregular and small segmented regions. Compared with other level set methods, the proposed approach relies on the optimum decision of pixel classification and the estimates of prior probabilities; thus the approach has more reliability in theory and practice. Experiments show that the proposed approach is able to extract the complicated shapes of targets and robust for various types of medical images. Moreover, the algorithm can be easily extendable for multiphase segmentation.     

Compensation of unknown sinusoidal disturbances in linear plants of arbitrary relative degree

A new algorithm is proposed for compensating parametrically uncertain harmonic disturbances. In contrast to the known results, the compensation is carried out in the situation where only the output variable and the control signal are measured, and the relative degree of the plant is arbitrary.     

Optimality conditions of sliding modes and the maximum principle for control problems with the scalar argument

Various types of optimality criteria and conditions, which define the set of admissible solution, are brought to the canonical form. For the problem set in this form, the optimality conditions of sliding modes are stated. It is shown that the optimality conditions emerge from these conditions in the form of the maximum principle for problems with a scalar argument and an arbitrary combination of the optimality criterion and constraints.     

Problem of reconstructing input signals under communication constraints

For a linear controllable system, the problem of reconstruction of all input signals, which are compatible with the measured signal, is considered. It is assumed that information can be transmitted in a processing center only via digital communication channel at discrete time instants, and the word length is limited. In this connection, there are encoding and decoding devices in the communication channel. For simplicity, the communication channel is assumed to be noiseless and delay-free. Defining relationships are obtained for the set of compatible input signals, as well as relationships between reconstruction precision, length of transmitted word and transmission frequency.     

A tracking problem for mechanical systems with delay in control

A problem of tracking for mechanical systems described by nonstationary nonlinear equations is studied at relay control with delay is studied. An approach that makes it possible to solve problems of tracking for mechanical systems whose parameters may continuously vary with time is developed. This approach is based on the transformation of the system and construction of a Lyapunov vector-function with components of the form of vector norm.     

Estimation of non-stationary delay for a linear discrete dynamic plant

A nonlinear recurrent gradient-type algorithm is proposed for estimation of nonstationary delay arising in finite impulse response of a linear discrete dynamic plant. Convergence of the algorithm is investigated. Using linear matrix inequalities, its optimal functioning is investigated in order to provide for the maximal rate of convergence of the estimation error to zero.     

Approximate solution of two-point boundary value problems for linear in control systems

The two-point boundary value problem for nonlinear systems, linear in unbounded control, is considered. For three-dimensional systems we present a local algorithm of approximate solution to the control problem. On the basis of this algorithm were constructed algorithms of approximate solution to the control problem on the 3-dimensional integral manifold (orbit) of n-dimensional systems with 2-dimensional control. Demonstrating examples are presented.     

Operating ratio of the technical systems,subjected to failures

The original way of definition of operating ratio in view of reliability of the equipment of the control, time of the control over periodic checks and time of restoration is offered. The received results allow to define the best value of operating ratio of system both in view of, and without taking into account operational expenses.     

Topological method for analysis of periodic canards

Singularly perturbed systems of ordinary differential equations are studied. A method for analysis of canard-type trajectories in such systems based on the topological degree theory is suggested. The method does not require smoothness of the right-hand side of the system. A result on the existence of periodic canards in systems with non-smooth perturbations is obtained. The trajectories located in this way are not necessarily Lyapunov stable, and appropriate control algorithms are required to stabilize them, e.g., feedback control.     

A class of systems of bilinear integral Volterra equations of the first kind of the second order

A class of bilinear systems of integral Volterra equations of the first kind related to the problem of automatic control of a nonlinear dynamic system (object) with unknown structure and vector input and output is studied. Algorithms for an analytic solution to corresponding bilinear systems and its numerical approximation are developed. A special character of the algorithms is illustrated by model examples.