The article considers the issue of improving the design of the laser head casing in order to ensure its compactness and take into account the capabilities of additive equipment that allows making more complex plastic casing parts without violating the collectability and maintainability of the laser head casing. The manufacture of a laser head casing made of plastic makes it possible to reduce its material consumption in comparison with a casing made of aluminum alloy. At the same time, it is proposed to further reduce the material consumption of the plastic casing due to the introduction of special recesses and stiffening ribs into its design. In the CAE-module of the CAD/CAM-system SolidWorks, a comparative analysis of the strength and stiffness of the laser head casing design options, assembled from parts with recesses and stiffeners, as well as without them. The modeling results of the deformation process for the casing variants convincingly showed that it is possible to replace the material of its parts from aluminum alloy to plastic and that reducing the material consumption and changing the design of the casing does not lead to such a loss of its strength and rigidity which causes an unacceptable deviation of the laser beam from the vertical, that is, does not affect the functioning of the laser head.

Based on analytical solutions for several torsion waveguides, transition matrices are derived, which are then used to calculate torsional vibrations using initial parameters. The paper contains a comparative analysis of different types of concentrators. As the waveguide’s design scheme, a rectilinear rod of the variable cross-section with various fastening types is adopted. The method of numerical determination of natural frequencies and waveforms of the waveguide of an ultrasound medical instrument (UMI) is presented. For a given waveguide layout, the amplitude angles of rotation and torques in the UMI are calculated at a specific frequency of oscillation excitation. A satisfactory agreement of the obtained results is demonstrated.

The article considers small vibrations of a spatial helical rod included in the longitudinal-torsional transducer of an ultrasonic medical instrument. An algorithm for determining the natural frequencies and waveforms of system vibrations by the method of initial parameters is developed. On the basis of this algorithm the real elastic element of the longitudinal-torsional transducer is calculated using the mathematical package MATLAB. The obtained natural frequencies allow ensuring the operation of the ultrasound medical instrument in the resonant mode.

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In 2020, the International Maritime Organization (IMO) plans to introduce a new environmental standard, called IMO Tier III. According to the future norm, the maximum permissible sulfur concentration in the exhaust gases of ship's engines for the whole world will be 0.5%, and for the emission control areas-0.1%. There will be difficulties in sea transportation to implement this norm, as heavy fuel is used in transport vessels for the works of power plants today, and such fuel does not meet the IMO Tier 3 requirement. This problem is acute for oil tankers, because they are fueled is spent not only for traffic, but also for heating the transported cargo-approximately in equal proportions. The paper suggests ways to solve the problem with fuel for ships, especially for tankers, in order to meet the requirements of IMO Tier 3. No method is absolutely preferable. To achieve the goal set in this paper, a review and analysis of all the existing methods of solving the problem is carried out. Comparison of different types of fuel as an alternative for use on ships is performed. The use of traditional fuels with the use of additional equipment (scrubbers) is analyzed. Presented are the prospects of using a two-stage waste heat boiler, which provides a reduction in fuel consumption of up to 7% in oil tankers. Options are subject to analysis on environmental and economic indicators in order to find the best way to solve the problem presented.