Volga State University of Water Transport

About: Volga State University of Water Transport is a education organization based out in Nizhny Novgorod, Russia. It is known for research contribution in the topics: Attractor & Creep. The organization has 71 authors who have published 75 publications receiving 224 citations.

Quality of Rolled Steel for Cold Bulk Stamping

Abstract: Metal products obtained from rolled blanks by cold upsetting are used in every branch of manufacturing. The quality of such components is assessed in terms of the required chemical composition and the plasticity, the consistency of the mechanical characteristics over the whole length, and the lack of internal and surface defects. If such metal components are to be competitive, all the steps in the production chain must be optimized: from smelting of the steel to cold upsetting of the product. In attempting to minimize costs and ensure the required quality, it is important to ensure safety and to decrease energy and labor costs in manufacturing. In this chain, the preparation of the material for cold bulk stamping is a key step. The high-strength fasteners obtained by cold upsetting are most often made of chrome steel. Recently, alternative boron-bearing steels have been actively introduced. However, their thermal hardening in quenching is unstable because boron oxides and nitrides may be formed, with decrease in their hardenability. In addition, chrome steels are 12–16% cheaper, as a rule. Also, since foreign supplies of boron steels are associated with additional costs, fasteners made of boron steels are even more expensive. That is a further impetus to using chrome steels. In the present work, we obtain standard mechanical characteristics and failure criteria for 40Kh steel components patented in a saltpeter bath at different temperatures, with subsequent drawing. The optimal preparation of the rolled steel in terms of its structural and mechanical characteristics after cold bulk stamping is determined: patenting (in a saltpeter bath at 400°C) and drawing (with 5–10% reduction). Such treatment yields products of the required quality and is preferable to the existing technology.

Nonuniform heating of a substrate in evaporative lithography

Abstract: This work is devoted to a method to generate particle cluster assemblies and connected to evaporative lithography. Experiments are carried out using nonuniform evaporation of an isopropanol film containing polystyrene microspheres in a cylindrical cell. The local inhomogeneity of the vapor flux density is achieved by exploiting the temperature gradient. A copper rod is mounted in the central part of the bottom of the cell for further heating. The thermocapillary flow resulting from the surface tension gradient, due in turn to the temperature drop, transfers the particles that were originally at rest at the bottom of the cell. The effect of the initial thickness of the liquid layer on the height and base area of the cluster formed in the central region of the cell is studied. The velocity is measured using particle image velocimetry. A model describing the initial stage of the process is developed. The equations of heat transfer and thermal conductivity are used to define the temperature distribution in the liquid and in the cell. The fluid flow is simulated using the lubrication approximation. The particle distribution is modeled using the convection–diffusion equation. The evaporation flux density is calculated using the Hertz–Knudsen equation. The dependence of the liquid viscosity on the particle concentration is described by Mooney's formula. Numerical results show that the liquid film gradually becomes thinner in the central region, as the surface tension decreases with the increasing temperature. The liquid flow is directed to the heater near the substrate, and it transfers the particles to the center of the cell. The volume fraction of the particles increases over time in this region. The heat flow from the heater affects the geometry of the cluster for two reasons: First, the Marangoni flow velocity depends on the temperature gradient, and second, the decrease in film thickness near the heater depends on the temperature. The results of the simulation are in general agreement with the experimental data.

Modeling Internet Business Optimization Processes

Abstract: Is considered a number of aspects of evolution of Internet business, in particular, assessment of efficiency of this innovation technology in terms of satisfaction of requests and needs of end users is implemented. The mathematical model is synthesized and modeling of set of processes is carried out. The analysis of results of such modeling allowed authors to formulate an entity of the concept “trust level” to information telecommunication technologies and to offer a way of its assessment, by definition of the so-called “index of trust of Internet users”. This index also to some extent reflects priorities of end users and can quite serve as a peculiar indicator of drivers of growth of the Internet in general and the Internet of things in particular.

Electrodynamic Characteristics of Dipole Antennas Made of Graphene-Containing Carbon Fiber Composite Materials

Abstract: The electrodynamic characteristics of dipole antennas made of carbon fiber composites with a graphene-containing binder have been investigated at 200 and 600 MHz. It is shown that main characteristics of antennas, including the standing wave ratio, radiation pattern, and gain factor, coincide with characteristics of their metal analogs. The effect of conductive properties of the metal–carbon fiber composite contact in the dipole radiating elements on the parameters of the antennas is estimated.