On the route construction in changing environments using solutions of the eikonal equation

The article deals with the vehicle routing problem in an environment with dynamically changing properties. The problem is relevant in current conditions when the delivery cost has a steady upward trend and is often comparable to the cost of the product itself. A central feature of the study is that the optimality criterion is the minimum delivery time, but not the distance traveled. The optical-geometric approach developed by the authors, based on the analogy between the propagation of light in an optically inhomogeneous medium and the minimization of the integral functional, is used as a research tool. We use exact and approximate solutions of the eikonal equations to describe wave fronts. Two original numerical algorithms for route construction are proposed and implemented as software. A computational experiment is performed that justified the effectiveness of the proposed model-algorithmic tools.

Radiation hardening and optical properties of materials based on SiO2

Preliminary studies have shown that the optical absorption spectra of radiation-colored glasses correspond to the spectral behavior of the scattering losses of an optically inhomogeneous medium. The reasons for the same optical changes in glasses of different compositions are the radiation-induced electric charge separation in the structurally nano-inhomogeneous glass volume, polarization and formation of nanometer optical inhomogeneities. The authors of this work prove that the radiation changes in the mechanical and optical properties of silicate glasses are of the same nature. The performed estimates indicate that the electric charge separation in the glasses occurs up to absorbed doses of about 1 MGy. The local electric charge separation due to the appearance of Coulomb forces leads to radiation hardening of the glasses. The estimated Coulomb hardening of the quartz glasses was ~ 107 Pa. The theoretical results were experimentally confirmed by measuring the mechanical properties of the glasses under high intensity proton irradiation as well as by testing the mechanical strength of a composite material based on quartz glass. Under proton irradiation with a dose rate of 5×103 Gy/s (energy of 8 MeV) up to threshold doses of ~ (1 – 5) ×106 Gy in the KU-1 quartz glasses, the decrement of acoustic vibrations decreased due to Coulomb hardening. After gamma irradiation with 1.34×105 Gy, the tensile strength of the composite material based on quartz glass increased by up to 20 MPa. This value is in the range of estimates of Coulomb hardening of quartz glasses. It is also shown that ionizing radiation does not affect the elastic modulus of materials based on SiO2.

Highly Accurate Computer Modeling of Light Propagation in Inhomogeneous, Anisotropic Medium for the Acousto-Optical Phenomenon

We present a novel numerical model that simulates the anisotropic Bragg diffraction in optically anisotropic (uniaxial) acousto-optical devices. We use a non-paraxial vectorial beam propagation method adapted to optically inhomogeneous medium and arbitrary optical field distribution. The principal idea of our solving method is that since the amplitude of the spatial variation of the refractive index caused by the acoustic wave is relatively small, we can consider it as a perturbation and iterate to the exact solution of the wave equation describing the propagation of the optical field distribution. To describe anisotropic diffraction with polarization rotation, we use a fully vectorial beam propagation method (BPM) where the accuracy depends on the relative step size. The results converge rapidly to fulfill energy conservation (up to 10–3 with less than an hour of computational time). We show that the calculated angles, the space dependent intensity and polarization variations of the diffracted beams agree accurately with those predicted by theory and experiment, under Bragg diffraction condition, in various acousto-optic configurations.