Table of Contents

  • Increasing Bitrate Speed Using Artificial Intelligence in WDM C-Band Systems Based on Silicon Nitride Waveguide Structures

    pg(s) 3-5

    Back reflection challenges significantly constrain the efficiency of optical communication networks utilizing dense wavelength division multiplexing (DWDM) technology based on silicon multimode interference (MMI) waveguides. To address this issue, we propose an innovative 1×4 optical demultiplexer design based on MMI within a silicon-nitride (SiN) strip waveguide configuration that operates within the C-band spectrum. Our simulation outcomes indicate that the proposed device efficiently transmits four channels with 10 nm spacing in the C-band, exhibiting low power loss ranging from 1.99-2.36 dB, extensive bandwidth of 7.69-8.09 nm, and good crosstalk values between 20.7-23.5 dB. Utilizing the low refractive index of SiN, we achieve exceptionally low back reflection of 40.58 dB without requiring specialized angled MMI designs, typically needed in Si MMI technology. Hence, this SiN-based MMI demultiplexer technology can be effectively employed in DWDM systems to achieve high data transfer rates with minimal back reflection in optical communication systems

  • Comparison of gear diagnostic methods used in the space industry

    pg(s) 6-7

    The basic method for examining the condition of gears is the vibroacoustic method. This method is widely used around the world for diagnostic purposes. However, it is not always possible to use it. This especially applies to mechanisms operating ultimately in space. Harsh working conditions, the presence of the vacuum of space, radiation, reactive oxygen ions and many other factors make diagnostics in this environment much more difficult. This article compares vibroacoustic, electrical, optical and other methods in terms of their potential application for diagnostic purposes of gears used in the space industry.

  • Detection of sonochemical hydrogenation effect in the process of hydro-vacuum dispersing of melts and its Significance

    pg(s) 8-13

    The study is devoted to the identification of technological features of the process of hydrovacuum dispersion (atomization) of liquid aluminium, which provides the accompanying self-generation of the effect of sonochemical hydrogenation of the obtained particles. In order to explain this phenomenon, the study reveals the design and functional features of a special, actually developed installation of continuous vertical suction and dispersion of metallurgical melts. Here the graphical scheme-model of influence of ultrafrequency cavitation pulsation generated by shock waves of hydraulic rarefaction, cumulative splitting of water molecules and sonochemical introduction of released hydrogen in solidifying particles of atomized aluminum melt is reconstructed. The results of the revealed sonochemical hydrogenation process are clearly illustrated by both electron microscopy images and X-ray diffractometry and FTIR spectroscopy. It is established that during hydrovacuum atomisation free hydrogen can be dissolved and retained in aluminum microparticles, both with the formation of blown (foamed) clusters of diffusion-amorphous hydrogenation, and – solid solution of embedding, in the form of crystals of face-centred cubic syngony.

  • Research of the local powder materials permeability

    pg(s) 14-17

    A method for determining the local permeability of powder filtering materials (PFM) based on the measurement of gas-flows sequentially passing through the measuring head and different areas of the measured object (sample, product), and a device for its implementation are described. The device is characterised by simplicity of execution and can be used both in laboratory and production conditions. By the average value of localised flow rates the throughput capacity of the whole product can be estimated.

  • Experimental measurements of magnetocrystalline anisotropy constants of evaporated cobalt-based thin films

    pg(s) 18-21

    Under a base pressure of 10-7 mbar, we used physical vapor deposition process to fabricate cobalt-based thin films onto monocrystalline silicon Si (100) substrates. The incident atomic beam reaches the substrates under normal incidence within a home-made evaporation chamber. The thickness of the synthesized films ranges from 50 to 400 nm. From X-ray diffraction measurements we infer that the samples are polycrystalline, through a hexagonal close packed structure and display a <0001> preferred orientation. The crystallite sizes increase with the magnetic layer thickness increase. The films are subject to a compressive stress. Magnetic force microscopy images exhibit stripe patterns for the thickest films and hysteresis loops infer that the easy magnetization vector lies in the film plane. We used Brillouin light scattering tool to measure magnetic anisotropy factor. Values of Ku higher than 106 erg.cm-3 have been measured.

  • Optical properties of polymer-CNT thin films

    pg(s) 22-25

    The influence of external factors (heat treatment, high pressure) on the optical properties of the samples was analyzed. It was established that samples of pure PTFE4 after the specified external influence increase their throughput, while the largest increase in throughput is observed for samples that were obtained under high pressure, and for samples that were subjected to heat treatment during synthesis, an increase in throughput is characteristic ability with increasing synthesis temperature. For PTFE-4 composites from 5 wt. % CNT (film thickness h=200 μm) samples become opaque in the wavelength range λ=320-1000 nm and regardless of the method of their production, which indicates the possibility of using such materials as absorbing coatings.

  • On the character of rate primary recrystallization of steels in the zone of laser action

    pg(s) 26-29

    The features of high-speed primary recrystallization of the cold-worked steels with different chemical composition and structure in the laser impact zone are studied. It has been established that during laser heating of the cold-formed steels, either polygonization or primary recrystallization occurs, which has a dynamic character. It is shown that the range of degrees of cold rolling, at which the character of structure recovery changes from polygonization to recrystallization, increases from 25…30 to 50…60%. The effect of heredity of the cold deformation substructure is revealed. It has been found that the density of dislocations in the surface layer after laser exposure increases by more than an order of magnitude due to plastic shears that introduce forest dislocations. It is shown that in the zone of laser treatment there are signs of columnarity of recrystallized grains and subboundaries, as well as a crystallographic texture.

  • Microstructure and properties of Ti-TiС composite obtained by hot pressing

    pg(s) 30-32

    Direct Metal Laser Sintering (DMLS) is a revolutionary technology that allows a production of fully functional metal parts directly from a 3D CAD data, eliminating the investment to production tools and technologies which brings considerable cost and time savings. Metal parts made by DMLS technology are fully comparable with casted or machined parts. A range of application of DMLS technologies is very wide – from prototypes, through short-run production to final products. Advantages of DMLS technology are arising along with complexity of parts – more complex geometry of parts (in terms of shape and occurrence of the detail) make DMLS technology even more
    economically effective.

  • Deposition of cobalt alloy protective coating on titanium against negative effects of hydrogen environment

    pg(s) 33-35

    The protective coating on a cubic-shaped titanium sample was deposited by the plasma method in an argon atmosphere in several stages, in order to form a continuous barrier on all surfaces of the sample. It was shown that, when the protective coating was deposited by the specified method, partial or complete melting of the powders occurred, and subsequently, when they were deposited on the surface of the substrate, active interaction occurred. This made it possible to form a sufficiently continuous layer on the surface of titanium due to mutual diffusion. It is found out that the deposited protective coating allows titanium to be heated up to 400 ± 10 °C in a hydrogen atmosphere (hydrogen pressure 0.6 ± 0.2 MPa) without interaction with the gas.

  • Characterization of self-cleaning coated composite materials for solar cells applications

    pg(s) 36-38

    The development of solar cell technologies is critical for advancing sustainable energy solutions. One of the significant challenges faced by solar cells is the accumulation of dust and debris on their surfaces, which can significantly reduce their efficiency. Our research work will be focused on new development composite material which are designed to repel dirt, dust, and other contaminants, ensuring that the solar cells maintain optimal performance. The optimum WO3-B composition was utilized in this research work to prepare the SiO2/WO3- B5/ZnO film sample. The composite film sample resulted the highest photocatalytic dye degradation efficiency (92%) with the SiO2/WO3- B5/ZnO/70/30) film sample after 240 min of the UVA light irradiation.

  • Influence of ultrasound in the production of Frass extracts

    pg(s) 39-39

    The current direction of development is the Green Deal, the main objective of which is to create a sustainable and modern economy without harming the environment. In order to avoid the negative effects of intensive farming, various options for sustainable agriculture are often proposed such as partially replacing synthetic fertilizers and replacing chemical plant protection measures with biological ones [1]. Residues from other agricultural branches can be used as an alternative raw material to produce fertilizers. The current trends in insect breeding, which are gaining wider applicability and legalization for use in the food industry, also create opportunities for the development of waste treatment methods. In Lithuania, the cultivation of insects is developing rapidly, which means that the amount of frass will also grow rapidly, so finding effective ways to use it are essential.