PREPARATION AND LYOPHILIC PROPERTIES OF CHITOSAN AEROGELS MODIFIED WITH GLYCYDYL METHACRYLATE COPOLYMERS

The article presents the results of a study of the properties of chitosan spongy materials (aerogels) surface modified with copolymers of glycidyl methacrylate. The surface of the obtained materials is characterized by a highly hydrophobic state with contact angles at the initial time moment more than 140 degrees, while a decrease in water absorption of aerogels and a slight decrease in oil absorption are also observed as a result of the modification.

Plastic response of conical shells with stiffeners to blast loading

The inelastic response of circular conical shells to the blast loading is studied. The impact loading is applied at the initial time moment and it is removed at a certain instant of time. The load intensity depends of the coordinate of the shell. The material of the shell is a perfect plastic one obeying the Johansen yield condition and the associated flow law. It is assumed that the frustum of the cone is furnished with ring stiffeners made of the same material. A theoretical method for the evaluation of the stress strain state of the shell and for determination of maximal residual deflections is developed.

Microchannel cleaning by the external laminar flow

The paper is devoted to study of the cleaning a microchannel contaminated by solute particles deposited on channel walls. The main and the most common cause of microchannel clogging is sorption of solute particles on channel walls or “physical sorption”. In this paper, we study the problem of the drift of solid non-interacting particles into a microchannel, which can stick to its walls due to Van der Waals interactions and break away from the wall due to viscous stress. A constant pressure drop is fixed between the inlet and the outlet of the channel. At the initial time moment, the channel walls are contaminated with adhering particles, i.e. the form of walls affects the formation of the flow structure through the channel. Over time, under the action of viscous stress the particles detach from the channel walls, thus cleaning occurs. The interaction of the detached particles with the flow is taken into account within the Stokes approximation. In addition, the model takes into account random walks caused by diffusion. The problem is solved numerically in the framework of the random walk model. The evolution of the fluid flow in the channel during its cleaning is obtained. The dependences of the concentration of settled particles on the flow rate and the strength of the Van der Waals interaction between particle and wall are determined. The dependence of the flow rate through the channel cross section on the concentration of settled particles was investigated. The channel cleaning time was estimated.

Estimation of the parameters of barbell’ lifting law of motion

Characteristic points of the law of motion were determined based on the results of experimental study on the velocities and accelerations of the lifted barbell. Relationship between the height of the athlete, lifted weight, maximal velocity and acceleration was estimated analytically. It was shown, that at the initial time moment the athlete must apply approximately 1,5 times larger force than lifted weight. The values of the parameters of the barbell’ law of motion and lifting force approximate law of change were estimated.

Boundary Value Problems for Fourth-Order Sobolev Type Equations

The goal of the article is the study of solvability in the Sobolev spaces of boundary value problems for some classes of Sobolev-type fourth-order linear equations. We will prove that an initial boundary value problems well problems with data both at the initial time moment and the final time moments can be well-posed for the equations under study