Study of the strength dependence of concrete for mine construction on the content of coal mining waste in it

The possibility of using coal mining waste in mine concrete mixing is considered in the article. As a result of the research, scientific and practical results have been obtained that make it possible to evaluate the strength properties of mine concrete, depending on the content of coal dust particles - the waste of mining - in it. It has been experimentally proven that when a fine fraction of coal is added to mine concrete, the strength of concrete decreases at a certain ratio, but this strength is sufficient to ensure the required properties. As a result of the experiments, samples of concrete for mine construction were manufactured, into which a fine fraction of coal - coal dust - was added in various ratios. A series of mine concrete tests was carried out to determine its physical and mechanical properties; the optimal composition was determined, which provides process and strength performance of the mixture. The conclusions have been drawn about the quantitative content of a fine fraction of coal in mine concrete, which make it possible to maintain process performance of the mixture and the strength of structures.

Effect of mechanical treatment type on the strength of undoped single crystal indium antimonide wafers

Thin (100) wafers of single crystal undoped InSb have been strength tested by plane transverse bending. The strength of the wafers (≤ 800 mm in thickness) has been shown to depend on their mechanical treatment type. If the full mechanical treatment cycle is used (grinding + chemical polishing) the strength of the InSb wafers increases twofold (from 3.0 to 6.4 kg/mm2). We show that the strength dependence on mechanical treatment type for (100) wafers is similar to that for (111) wafers, the strength of (111) wafers being 2 times higher. The roughness of the thin wafers after the full mechanical treatment cycle has been measured using contact profilometry. After the full mechanical treatment cycle the roughness of the InSb wafers Ra decreases from 0.6 to 0.04 mm leading to general surface smoothening. We have compared the strength and roughness between (100) InSb and GaAs wafers. The roughness of InSb and GaAs wafers after the full mechanical treatment cycle decreases significantly: by 10 times for InSb due to the general surface smoothening and by 3 times for GaAs (Rz from 2.4 to 0.8 mm) due to a reduction of the peak roughness component. The full mechanical treatment cycle increases the strength of InSb wafers by removing damaged layers through the sequence of operations and reducing the risk of mechanical damage development.

Fractal Plots of Topology Optimization Efficiency in Solving of the Problem for Strength Dependence on the Grid

In this research is solved the problem for determining of dependencies describing the strength redundancy of a part obtained by means of topology optimization using the SIMP method under a variety of grid’s finite elements. For this purpose, in the research was performed a digital experiment, during which almost fifty variants of part’s computer models were obtained, and their mechanical properties were studied. Based on the obtained data were constructed plots for the strength efficiency of topological optimization, which reflect fractal properties of part’s strength parameters changing. Upon reaching the research goal were solved the problems of software selection and applying a programs combination, which allowed automate the creation of models based on the topology optimization results. The main tool for topology optimization was the Autodesk Fusion 360 product, providing a free access to cloud computing, and Autodesk ReCap Photo was used when models converting. On the results of the experiment were formulated recommendations for obtaining the part’s optimized topology without critical defects of shape, using the SIMP method. With great probability, these recommendations are important when using other methods for topological optimization, such as ESO, BESO, or Level-Set. The received recommendations were tested in solution the problem of increasing the structures’ strength efficiency on the example of the rocker-Bogie wheel suspension using in modern Curiosity-type Mars rovers. The topology optimization results are openwork parts that can withstand heavy loads at low weight. This was confirmed by strength analysis, which had showed an increase in specific strength up to 13.5 times, relative to the prototype used in the Curiosity-type Mars rover’s suspension.

Temporal Fluctuations in Interparticle Interactions Drive the Formation of Transiently Stable Nanoparticle Precipitates

<p></p><p>The pH and ionic strength dependence of electrostatic interactions was explored to introduce temporal fluctuations in the strengths of interparticle interactions and choreograph a transient self-assembly response in plasmonic nanoparticles. The assembly process was triggered by the electrostatic attraction between positively-charged gold nanoparticles (AuNPs) and an aggregating agent, ethylenediaminetetraacetic acid (EDTA). The autonomous changes in the pH and ionic strength of the solution, under the influence of atmospheric CO₂, weaken the aggregating ability of EDTA and initiate the complete disassembly of [+] AuNP - EDTA precipitates. The non-destructive way of disassembly minimizes the generation of waste, which helped in achieving some of the desirable feats in the area of dynamic self-assembly like easy removal of waste, transiently stable precipitates and negligible dampness. The chemical strategy adopted in the present work, to introduce transientness, can act as a generic tool in creating the next generation of complex matter.</p><br><p></p>

Temporal Fluctuations in Interparticle Interactions Drive the Formation of Transiently Stable Nanoparticle Precipitates

<p></p><p>The pH and ionic strength dependence of electrostatic interactions was explored to introduce temporal fluctuations in the strengths of interparticle interactions and choreograph a transient self-assembly response in plasmonic nanoparticles. The assembly process was triggered by the electrostatic attraction between positively-charged gold nanoparticles (AuNPs) and an aggregating agent, ethylenediaminetetraacetic acid (EDTA). The autonomous changes in the pH and ionic strength of the solution, under the influence of atmospheric CO₂, weaken the aggregating ability of EDTA and initiate the complete disassembly of [+] AuNP - EDTA precipitates. The non-destructive way of disassembly minimizes the generation of waste, which helped in achieving some of the desirable feats in the area of dynamic self-assembly like easy removal of waste, transiently stable precipitates and negligible dampness. The chemical strategy adopted in the present work, to introduce transientness, can act as a generic tool in creating the next generation of complex matter.</p><br><p></p>