Mathematical modeling and analysis of Phytoplankton–Zooplankton–Nanoparticle dynamics

In this paper, we investigate the population dynamics of phytoplankton–zooplankton–nanoparticle model with diffusion and density dependent death rate of predator.  The functional response of predator in this model is considered as Beddington–DeAngelis type.  The stability analysis of the equilibrium points is observed by applying the Routh–Hurwitz criterion.  Numerical simulations are given to illustrate the theoretical results.

On the maximal output set of fractional-order discrete-time linear systems

In this paper, we consider a linear discrete-time fractional-order system defined by \[\Delta ^{\alpha }x_ {k+1}=Ax_k+B u_k, \quad k \geq 0, \quad x_{0} \in \mathbb{R}^{n};\] \[y_{k}=Cx_k, \quad k \geq 0,\] where $A$, $B$ and $C$ are appropriate matrices, $x_{0}$ is the initial state, $\alpha$ is the order of the derivative, $y_k$ is the signal output and $u_k=K x_k$ is feedback control.  By defining the fractional derivative in the Grunwald–Letnikov sense, we investigate the characterization of the maximal output set, $\Gamma(\Omega)=\lbrace x_{0} \in \mathbb{R}^{n}/y_

State regulation of stability and effectiveness of money systems

The problems of stability providing by the way of using criterion of effectiveness of money systems models in the transitional and modern economys are researched. The methodological approaches with the increasing of effectiveness and stability of money systems through the possibility of achievement of certain economic and social priorities are considered.

Calculation of stable and unstable periodic orbits in a chopper-fed DC drive

It is well known that electric drives demonstrate various nonlinear phenomena.  In particular, a chopper-fed analog DC drive system is characterized by the route to chaotic behavior though period-doubling cascade.  Besides, the considered system demonstrates coexistence of several stable periodic modes within the stability boundaries of the main period-1 orbit.  We discover the evolution of several periodic orbits utilizing the semi-analytical method based on the Filippov theory for the stability analysis of periodic orbits.  We analyze, in particular, stable and unstable period-1, 2, 3 and

On the asymptotic output sensitivity problem for a discrete linear systems with an uncertain initial state

This paper studies a finite-dimensional discrete linear system whose initial state $x_0$ is unknown.  We assume that the system is augmented by two output equations, the first one $z_i$ being representing measurements made on the unknown state of the system and the other $y_i$ being representing the corresponding output.  The purpose of our work is to introduce two control laws, both in closed-loop of measurements $z_i$ and whose goal is to reduce asymptotically the effects of the unknown part of the initial state $x_0$.  The approach that we present consists of both theoretical and algorit

Application of frequency stability criterion for analysis of dynamic systems with characteristic polynomials formed in j1/3 basis

This paper considers the stability of dynamical systems described by differential equations with fractional derivatives. In contrast to a number of works, where the differential equation describing the system may have a set of different values ​​of fractional derivatives, and the characteristic polynomial is formed on the basis of the least common multiple for the denominators of these indicators, this article proposes forming such a polynomial in a specific

Study of the processing of small diagnostic creations on a fluid sourcing by spiral survivals

The article considers the features of the drilling process where there is a change in temperature, hole diameter, and displacement relative to the axis and the impact on the tool, when machining holes with high-speed steel drills there is wear of the transverse edge which is completely rounded to create a conical surface. There is a decrease in the negative value of the front corners on the transverse edge of the decrease in axial force, which led to a decrease in the intensity of wear of the transverse edge.

Positivity and stability of descriptor linear systems with interval state matrices

The positivity and asymptotic stability of descriptor linear continuous-time and discrete-time systems with interval state matrices and interval polynomials are investigated. Necessary and sufficient conditions for the positivity of descriptor continuous-time and discrete-time linear systems are established. It is shown that the convex linear combination of polynomials of positive linear systems is also the Hurwitz polynomial. The Kharitonov theorem is extended to the positive descriptor linear systems with interval state matrices.