Determining the efficiency and parameters of rubble strip reinforcement

The necessity of development and improvement of methods and means for the protection of preparatory roadways, in particular, protective structures, was proved on the basis of ordinary rock with binding surfaces. Analysis of the results of the study on the use of protective structures of ordinary rock and bounding surfaces was performed. It has shown the feasibility of reinforcing rock structures to ensure operational conditions for the protected roadways. Such structures include rubble strips reinforced with partitions made of metal mesh. To determine their efficiency and reinforcement parameters, studies were performed using provisions of structural mechanics, soil mechanics, and bulk media, as well as physical modeling using natural materials. According to the results obtained in the performed studies, the efficiency of reinforcement of rubble strips with a metal grid was proved and a procedure for calculation of reinforcement parameters that need to be considered in designing the above structures was developed. Such parameters include width and height of the strip, class of reinforcement, its diameter and tensile strength, size of the grid cells, angle of internal friction of rocks, and diameter of maximum rock pieces in the strip. It was established that reinforcement of the rubble strip by partitions made of metal meshes can reduce the width of the strip and volume of the rock fill by 1.33…2.66 times without losing the structure rigidity. To do this, the condition of reinforcement strength in grids must be met. It consists of comparing its tensile strength with maximum stresses in the partition. These stresses are determined by the magnitude of the load on the rubble strip from the roof rocks, the diameter of the reinforcement, and the maximum rock pieces, as well as relative extensional strain in reinforcement.

Comparison of the Masticatory Force (with 3D Models) of Complete Denture Base Acrylic Resins with Reline and Reinforcing Materials

The reinforcement of acrylic denture base remains problematic. Acrylic prosthesis fractures are commonly observed in prosthodontic practice and have not been reliably resolved. This study compared the resistance to masticatory force of acrylic bases of removable complete conventional prosthesis in 3D upper models. Forty acrylic base test specimens containing two types of reinforcement meshes (20 with glass fiber meshes (FIBER-FORCE®- Synca, Bio Composants MédicauxTM, Tullins, France), 20 with metal meshes (DENTAURUM®-Ispringen, Germany)), 20 with a conventional PMMA acrylic base (LUCITONE 199®-Dentsply Sirona, York, PA, USA), and 20 using a permanent soft reline material (MOLLOPLAST-B®-DETAX GmbH & Co. KG, Ettlingen, Germany) were tested—a total of 80 specimens. Half of the specimens were made for a low alveolar ridge and half for a high alveolar ridge. The data were analysed using one-way analysis of variance and Student’s t-test for independent test specimens. In the high-alveolar-ridge group, the prosthesis reinforced with the glass fiber mesh was the most resistant to fracture, while in the low-alveolar-ridge group, the non-reinforced prosthesis showed the highest resistance masticatory force. Prostheses with the permanent soft reline material showed the lowest resistance to fracture in both high and low-alveolar-ridge groups. The results show that the selection of the right reinforcement material for each clinical case, based on the height of the alveolar ridge, may help to prevent prosthesis fractures.

Vacuum-Free Fabrication of Transparent Electrodes for Soft Electronics

Optoelectronic devices are advancing from existing rigid configurations to deformable configurations. These developing devices need transparent electrodes (TEs) having high mechanical deformability while preserving the high electrical conductivity and optical transparency. In agreement with these requirements, vacuum-fabricated conventional TEs based on transparent conducting oxides (TCOs) are receiving difficulties due to its low abundance, film brittleness, and low optical transmittance. Novel solution-processed TE materials including regular metal meshes, metal nanowire (NW) grids, carbon materials, and conducting polymers have been studied and confirmed their capabilities to address the limitations of the TCO-based TEs. This chapter presents a comprehensive review of the latest advances of these vacuum-free TEs, comprising the electrode material classes, the optical, electrical, mechanical and surface feature properties of the soft TEs, and the vacuum-free practices for their fabrication.

ТЕПЛОТРАНСПОРТНАЯ СПОСОБНОСТЬ ФИТИЛЯ ИЗ МЕТАЛЛИЧЕСКИХ СЕТОК

In the manufacture of wicks for capillary transport of coolant in various heat transfer devices such as heat pipes, capillary pumped loop, accumulators with thermal regulation, evaporative heat exchangers, heat sinks, etc., capillary porous structures are used. Capillary and porous structures made of compressed powders (metal or non-metal) are widely used. However, the technology of making such porous structures is complicated and time-consuming. Important requirements for wicks are high capillary pressure, low-pressure drop, low weight, and manufacturability. Capillary porous structure, which meets these requirements, can be a wick made of several layers of metal mesh, superimposed on each other, and connected by contact welding. The main advantages of such wicks are low weight and ease of fabrication. The article deals with the methods and results of determining the limit heat transfer capacity of a free wick (not in contact with solid walls) of metal meshes. The design of an experimental unit is given, which allows testing not only at positive but also at small negative angles of the wick to the horizon. Experiments on ammonia to determine the limit heat transport capacity of a flat free wick made of two-layer metal mesh 0.2×0.13 mm woven weave is conducted. By results of the spent experiments dependence of limiting the heat-transport ability of a wick from the temperature of saturation of the heat carrier and an angle of slope to the horizon is received. The performed experiments allow for a wick of the given design to calculate its maximum heat-transport capacity in earth conditions at any width, a transport length of a wick, and an angle of slope to the horizon. Formulas for calculating the thermal transport capacity of wicks made of metal mesh of different length and width under microgravity conditions and in the field of gravity of the earth at different orientations are recommended. The results of the experiments allow determining the thermal transport capacity of wicks from metal meshes and in microgravity conditions.