The effect of stadial nitrogenization on the structure and properties of martensitic steel 13X11N2V2MF

A new method of gas nitriding is presented, which produces obtaining high-quality diffusion layers that meet the requirements of the use for various purposes, including aviation ones. Peculiar properties of highly alloyed martensitic steel nitriding after stadial thermo-gas-cyclic nitrogenization under partially dissociated ammonia with air additives have been examined. The results of metallographic studies, diagnostic leach, tests for wear resistance, impact hardness and corrosion stability, depending on the test mode are presented.

Functional Measurement Applied to Engineering Students’ Test Anxiety Judgment for Online and Face-to-face Tests

<p style="text-align: justify;">This study explored the cognitive mechanism behind information integration in the test anxiety judgments in 140 engineering students. An experiment was designed to test four factors combined (test goal orientation, test cognitive functioning level, test difficulty and test mode). The experimental task required participants to read 36 scenarios, one at a time and then estimate how much test anxiety they would experience in the evaluation situation described in each scenario. The results indicate three response styles (low, moderate, and high-test anxiety) among the participants. The orientation and difficulty of each given exam scenario were the most critical factors dictating test anxiety judgments. Only the moderate test anxiety group considered the test mode to be a third relevant factor. The integration mechanism for Cluster 1 was multiplicative, while for Clusters 2 and 3, it was summative. Furthermore, these last two clusters differed in terms of the valuation of the factors. These results suggest that programs that help students to cope with test anxiety need to take into account the valuation and integration mechanism that students use to integrate different information in specific examination contexts, since the way students assess their internal and external circumstances can influence how they deal with evaluative situations.</p>

Modern testing machines for investigation of wood and timber-based composite materials

A detailed analysis of test machines and presses operating in both soft (increasing loads) and hard test mode (displacement increase) has been performed. The results of tests of deciduous, coniferous and tropical timber species on modern test machines of foreign production under a strict test regime were analyzed. The results of tests of timber and concrete on advanced presses of old production with the help of additional equipment are also given and analyzed. With the help of such equipment it is possible to build a "stress-strain" diagram completely on the ascending branch and partially on the descending branch. And also allows you to more widely establish the strength and deformation properties of concrete and timber. It was found that the influence of age on the main strength and deformation parameters has not been studied. In recent decades, testing machines and presses have begun to appear, which allow to investigate these or those materials from the beginning of loading and to its full destruction. That is, to analyze the work of different materials (metal, timber, concrete, etc.) on the ascending and descending branches, and in particular in the so-called supercritical stage of work. At the end of the 20th century, scientists developed electromechanical and servo-hydraulic universal testing machines, which make it possible to test samples from the beginning of loading until complete destruction (rigid test mode for incremental displacements), while fixing all the necessary strength and deformation indicators on the ascending and descending branches of the diagram "stress - strain", setting the necessary modes and loading speeds. Measuring instruments determine the forces and deformations at different stages of testing and transmit the measurement results to the recording device or means of information accumulation. The characteristics of modern testing machines, in particular electromechanical and servo-hydraulic, are given: WDW (Time Group Inc.), INSTRON (USA), REM (Russia), LFM (Switzerland). The possibilities of the STM-100 servo-hydraulic testing machine for the study of timber and composite materials based on it are described in detail..

Effect of soil moisture content, dynamic load and wheel slippage in measuring traction in an indoor traction bed

A study was conducted to determine the effect of soil moisture content, dynamic load and wheel slippage in measuring traction. A single wheel test rig was developed to enable fundamental research on traction studies on tropical soil at the department of Agricultural and Environmental Engineering of Federal University of Technology, Akure. This facility consists of a moving carriage with a trolley that moves in either forward or reverse directions on rails well above a soil bin powered by 2.2 kW, three phase induction motor. The present facility set up was able to operate in either towing test mode for tire motion resistance studies or driving test mode for tire net traction and tractive efficiency studies. The test tire on the moving carriage was powered to rotate by a motor with additional pull provided by a cable-pulley mechanism connected to a tower with hanging dead weights. All controls on the moving carriage were activated from the main control console. The developed facility was successfully tested to determine tractive efficiency for narrow wheels at a particular inflation pressure on clay soil. The single wheel test rig facility worked well and the research indicates that wheel load, wheel slippage, soil moisture content and inflation pressure has great effect on traction efficiency. Traction efficiency decreased as the wheel load and wheel slippage increased. The developed single wheel testing facility can perform traction tests in controlled soil conditions to study the effect of soil, tire and moisture parameters on the performance of the system.

Calculation of the durability of sealing and awning materials

The article discusses the hypotheses for determining the equivalent laboratory modes for assessing the durability of sealing and awning materials, and evaluates the accuracy of the proposed method. Qualitative research of operational factors influence (UV, temperature) on sealing and awning materials durability was conducted. Purpose of the study: a method for predicting the durability of sealing and awning materials. Methods: Methods for fast assessment of durability and methods of equivalent factors. Results: Based on the obtained regularities of the behavior of sealing and awning materials under conditions of repeated loading and ultraviolet radiation, as well as the accepted hypotheses about the summation of damage and irreversibility of the destruction process, a laboratory test mode was determined that was equivalent in terms of the level of introduced destruction to the operating mode, including the action of multiple loads and ultraviolet radiation. Based on the equivalent accelerated test mode and the characteristics of the operating mode of loading and irradiation, a method for assessing the durability of sealing and awning materials is proposed.