A possibility of laser printing of graphene nanoribbon pixels while preserving the integrity of the structure and shape on the silicon substrate in accordance with the irradiated laser spot is demonstrated. To provide the transfer, a target consisting of a transparent sapphire plate and an absorbing thin titanium film (500 nm thick) coated with a film consisting of graphene nanoribbons is irradiated with a KrF excimer laser (λ=248 nm, τ=20 ns). Optimal conditions for laser irradiation are determined and a technique is developed for transferring a carbon nanomaterial from a growth nickel surface to a titanium film aimed at creating stronger bonds between the nanoribbons. Raman spectroscopy confirms the preservation of structural features of the synthesized atomically precise 7-atoms-wide graphene nanoribbons with an armchair edge during laser transfer.

The paper studies the real-time stereo image-based localization of a vehicle in a prior 3D LiDAR map. A novel localization approach for mobile ground robot, which successfully combines conventional computer vision techniques, neural network based image analysis and numerical optimization, is proposed. It includes matching a noisy depth image and visible point cloud based on the modified Nelder-Mead optimization method. Deep neural network for image semantic segmentation is used to eliminate dynamic obstacles. The visible point cloud is extracted using a 3D mesh map representation. The proposed approach is evaluated on the KITTI dataset and a custom dataset collected from a ClearPath Husky mobile robot. It shows a stable absolute translation error of about 0.11 – 0.13 m. and a rotation error of 0.42 – 0.62 deg. The standard deviation of the obtained absolute metrics for our method is the smallest among other state-of-the-art approaches. Thus, our approach provides more stability in the estimated pose. It is achieved primarily through the use of multiple data frames during the optimization step and dynamic obstacles elimination on depth image. The method’s performance is demonstrated on different hardware platforms, including energy-efficient Nvidia Jetson Xavier AGX. With parallel code implementation, we achieve an input stereo image processing speed of 14 frames per second on Xavier AGX.

The article studies properties of the harmonic simulation method within the framework of the spectral theory and evaluates the quality of this method. A review of the literature on the existing methods for modeling multidimensional random fields is carried out, making it possible to compare these methods using criteria such as the complexity of the algorithm, computational costs and memory requirements, requirements for the covariance function and the grid. Weaknesses are revealed, such as insufficient accuracy and high computational complexity, which are characteristic of spectral simulation methods in general, including the harmonic method. An analysis of forms of the signal simulated by the harmonic method for different bases reveals a property of centrosymmetry for square signals in the Fourier basis, a similar property for rectangular signals in the Fourier basis, the symmetry property of a square signal in the Hartley basis and the absence of such properties for a rectangular signal simulated in the Hartley basis. A comparative analysis of the accuracy of simulating two-dimensional signals, as a special case of multidimensional ones, is carried out by the harmonic method in the Fourier and Hartley bases. It is shown that, depending on the sampling characteristics, the simulated signal in the Fourier basis differs from the same signal simulated in the Hartley basis in terms of accuracy. As a result of the study, recommendations are worked out for choosing the basis in a specific problem of simulating two-dimensional signals. The effect of the discovered properties on the computational complexity of the method is described. Methods for applying these properties to simulate arbitrary two-dimensional signals are proposed.

We substantiate the necessity of developing a small-sized refractometer with Anderson's differential cuvette for the highly accurate rapid check of the state of liquid media in real time. Problems that arise in determining optimal design parameters of the optical part of the refractometer to reduce the measurement error of the refractive index ranging from 1.2300 to 2.2300 are indicated. It is noted that for the problem of determining optimal parameters of Anderson's differential cuvette to be addressed, an analytical expression for the medium refractive index nm needs to be deduced as a function of all parameters of the optical part of the refractometer. For the first time, an equation is derived to study a change in the trajectory of the laser radiation axis inside and outside of the Anderson cuvette, depending on its various parameters, values of the refractive indices of the reference and examined liquids, ns and nm. The design of a small-sized differential-type refractometer for measurements is developed and results of studying various liquid media are presented. The measurement error of the refractive index of 0.0001 in the developed design of the refractometer is confirmed. Directions of research for the further error reduction are outlined, that would allow the developed refractometer design to be used in scientific research and as a verification scheme in metrology.

The article briefly outlines a mathematical model for recognizing contours of the objects of interest in a raster image. The process of its discretization is discussed in more detail as part of the development of numerical methods that allow the proposed model to be implemented using modern computer technology, while achieving real-time performance. Explicit mathematical procedures suitable for writing application software codes are given, an estimate of computational complexity is obtained, and the possibility of achieving real-time performance is confirmed. Results of a numerical experiment on the reconstruction of spiral light beams are presented.

This paper presents the automated system for minimizing the deviation of the path of passage and the divergence of a secondary radiation source with parameters similar to ones of the main beam of a high-power Ti:Sa laser using mirrors in kinematic mounts on the motorized stages. As an alignment laser, the diode laser with a fiber output was used with radiation characteristics coinciding with the parameters of the main beam (wavelength, beam diameter). The successive approximation algorithm was used to minimize the beam deflection. The positioning accuracy and beam size matching were analyzed on the near-field camera and were equaled to 28.6 µm along the X-axis and 26.4 µm along the Y-axis. Beam size mismatch was equaled to 0.151 mm. The pointing accuracy was analyzed on the far-field sensor and equaled 15.34 µrad along the X axis and 12.03 µrad along the Y axis. The curvature of the wavefront was 0.06 µm.

Plasmonics is a field of research and technology that focuses on the interaction between light and free electrons in a metal structure called plasmon. The study of plasmonics has gained significant attention in recent years due to its potential for several applications and its ability to manipulate light at nanoscale dimensions. Plasmonics enables the control of light at the nanoscale, far beyond the diffraction limit of conventional optics. This allows for the development of new devices and technologies with enhanced performance and functionality. In this paper, recent advances in plasmonics in medicine, agriculture, agriculture, environmental monitoring, lasers and solar energy harvesting are reviewed. Despite these promising prospects, plasmonic devices must overcome obstacles such as significant energy losses, complicated production processes, and the need for better material characteristics. Plasmonics will continue to advance because of ongoing work in nanotechnology, material science, and engineering, which will make it a more significant field with a wide range of usages in the future. In the end, the advantages and the limitations related to the realization of plasmonic devices in the real world are discussed.

An original approach to solving difficult time-consuming problems of registration and analysis of random point images is described. The approach is based on the development and application of high-performance specialized computer algebra systems. Three software packages have been created specifically for carrying out equivalent analytical transformations on a computer. The first software system is designed to calculate formulas describing the volumes of convex polyhedra with parametrically specified boundaries in n-dimensional space. The second system is based on the calculation of multidimensional integral expressions by the method of cyclic differentiation of the integral with respect to the parameter. The third system is based on the accelerated implementation of complex combinatorial-recursive transformations on a computer. Another distinctive feature of the work is the extension of the classical Catalan numbers to the multidimensional case (they were required to solve a number of intermediate probabilistic-combinatorial problems). The implementation of the above computer algebra software systems on a multi-core cluster of Novosibirsk State University, together with the direct use of the explicit form of generalized Catalan numbers, allowed the authors to obtain several new previously unknown probabilistic formulas and dependencies required for solving problems in the field of analysis of random point images.

Spatial selectivity of six-wave radiation converters, which perform double wavefront conjugation of a signal wave in long multimode waveguides with both Kerr and thermal nonlinearities, is studied. Waveguides with infinitely conductive surfaces, with a parabolic refractive index profile, were used. It is shown that the spatial structure of the first pump wave does not affect the quality of doubled wavefront conjugation in a waveguide with Kerr nonlinearity, but only slightly affects the quality of doubled wavefront conjugation in a waveguide with thermal nonlinearity. A decrease in the radius of the second Gaussian pump wave on the back face of the waveguide leads to an improvement in the quality of the doubled wavefront reversal both in the case of six-wave interaction in the Kerr and thermal nonlinearities. In a parabolic waveguide, when the zero mode of the waveguide is excited by pump waves at a constant frequency of the second pump wave, an increase in the frequency of the first pump wave worsens the quality of the double wavefront conjugation.

The paper presents a study of various approaches to the classification of soil covers based on neural network algorithms using hyperspectral remote and proximal sensing of the Earth. The spectral distributions were recorded in the laboratory using an Offner imaging scanning hyperspectrometer. Spectral-spatial characteristics of nine soil samples from various parts of a farming land in the Samara region were experimentally studied. Using a method of energy dispersion microanalysis, the correspondence between the hyperspectral data and the chemical composition of the samples taken was established. Based on the data obtained, a neural network-aided classification of soil samples was implemented depending on the content of constituent elements such as carbon and calcium. A normalized spectral-spatial convolutional neural network was used as a classifier. As a result of the work, an approach to the classification of high-resolution hyper-spectral images based on the refinement of a multiclass convolutional neural network using an ensemble of binary classifiers is proposed. It is shown that the classification of soil samples by carbon and calcium content is carried out with an accuracy of 0.96.