Aggregation stability of mixtures of vacuum distillate and mazut

Chemistry and Technology of Fuels and Oils -     

Calculation of a parallel-plate waveguide with a chiral insert by the mixed finite element method

A parallel-plate waveguide with metallic boundaries, containing an insert of a chiral substance, is considered. The field distribution inside the insert is studied when the system is excited by the guide’s normal wave incident on the insert. The problem is considered in the full vector formulation. The waveguide is calculated by the mixed finite element method, which makes it possible to avoid spurious modes (so-called spirits).     

Photonic structures and their application for measuring material parameters

A computer simulation and an experimental study of the frequency dependences of the transmission coefficients of photonic crystals are carried out on the basis of microstrip lines with distortion in their periodicity in the form of change in the microstrip dimensions and the permittivity of a substrate of one of the alternate pieces of the microstrip line in the range of 0–20 GHz. Good quantitative agreement between the results of calculations and experimental data is obtained. It is shown that there is a possibility of using open microwave transmission lines, namely, microstrip photonic structures, to implement a method for measuring the parameters of material samples with the specified geometrical shape and a certain size that perform a function of nonuniformity in the photonic structure.     

A monitoring and measuring module for tagged neutron experiments

A tagged neutron technology for remote neutron monitoring is used to reduce the background counting rate in recording of useful events. The key elements of the technology are a neutron generator with a built-in α-particle detector, nanosecond electronic system, and fast detectors of secondary radiation produced by emitted neutrons. A module for monitoring and measuring the pulse-height and time parameters of the secondary radiation detector with a time reference to the α-particle detector is described. A prototype of the experimental setup comprising the main components of a standard system based on the tagged neutron technology has been designed to test the module. Numerical calculations have been performed to simulate the γ-ray and neutron transport and the event recording procedure as applied to the geometry of the experimental setup. The time errors and the main sources of background events in measurements using the tagged neutron technology have been investigated. Background counts are shown to affect only slightly the useful data acquired in this geometry.     

Mathematical modeling of waveguide transitions

Results of simulation of waveguide transitions performed at the Department of Mathematics of the Faculty of Physics, Moscow State University, are presented. Synthesis of waveguide transitions is based on the incomplete Galerkin method and the finite-difference technique formulated in the direct and projection forms (the finite-element method) and involves the Tikhonov regularization method.     

Calculation of dielectric waveguide systems using finite-difference method

Application of finite-difference (FDM) and finite-element (FEM) methods for the analysis of electromagnetic fields in dielectric structures and waveguides is considered. The main approaches to solution of these problems are discussed. Some new algorithms for such problems and their applications are presented.     

Variation of the type of resonance reflection of electromagnetic radiation from metal nanolayer-dielectric layer structures

Two types of resonance reflection of electromagnetic radiation from metal nanolayer-dielectric layer structures have been theoretically predicted and observed in experiment. These structures can obey the conditions of a half-wave resonance at a small metal layer thickness, and a quarter-wave resonance at a greater metal layer thickness.