New Analog Experiment for Convergent Regime an example of planet Mercury

<div> <div> <div> <div> <div> <div> <div> <div> <p>We conduct a series of experiments to understand the nature of thrust faulting as a result of global thermal contraction in planetary bodies such as Mercury. The spatial scales and patterns of faulting due to contraction are still not very well understood. However, the problem is complicated even for the homogeneous case where the crustal thickness and material properties do not vary spatially. Previous research showed that the thrust faulting patterns are non-random and are arranged in long systems. This is probably due to the regional-scale stress patterns interacting with each other, leading to the creation of coherent structures. We first conduct 1-Axis experiments where we simulate the contraction of the substratum using an elastic ribbon. On top of this we place the material for which the friction, cohesion and thickness can be controlled for each experiment. The shared interface between the frictional-cohesive material and the shortening elastic substratum dictates undulations and finally the generation of slip planes in the upper layer. We discuss the spatial distribution of these patterns spatially. We then speculate the interaction of such patterns on a 2D plane.</p> </div> </div> </div> </div> </div> </div> </div> <div> </div> </div><div> <div> </div> </div>

Proposing "analogy experiment" as a sub-category of "analog experiment" in earth science

<p>In the earth and planetary sciences, the term "analog experiment" indicates laboratory experiments that use analog materials to investigate natural processes. Scaled experiments constitute a representative sub-category of analog experiments. They are designed to have the same dominant dimensionless parameter in the same range as the targeted natural processes. Other primary uses of analog experiments are education and outreach. Reproducing similar phenomena in front of the audience is useful in explaining the essence of the complex dynamics of natural processes. However, it is often the case that we do not fully understand the physics of the experimental systems or the targeted natural phenomena. In such cases, especially when the process is complex, it is difficult to guarantee the scaling similarity. When we take such laboratory phenomena as a research subject of earth science, we encounter critical comments about the scaling issue.</p><p>Nevertheless, I think it scientifically important to consider questions like follows. What is the mechanism of the experimental phenomena? Why the behaviors of the experiment look similar to the natural phenomena? To what extent the laboratory and the natural systems are similar. To indicate experimental studies to elucidate these questions, I would like to define "analogy experiment" as a new sub-category of analog experiments.  Some recent experiments are presented as examples.</p>

An Investigation into Double Oxide Film Defects in Aluminium Alloys

When the oxidised surface of a liquid metal is folded over onto itself and entrained double oxide film defects are formed, which form crevices or cracks in the solidified casting, of varying sizes and orientations. These defects not only reduce mechanical properties, but also increase the scatter of properties. This paper reports an analog experiment to study the behavior of the interior atmosphere of double oxide film defects in Al alloy melts of varying Mg content. Air bubbles were trapped in melts of liquid Al alloy which were then solidified after holding for varying periods of time. The composition of the bubbles was subsequently measured using mass spectroscopy. This showed the reaction of oxygen from the bubble atmosphere to form oxides, followed by the consumption of nitrogen to form AlN. Simultaneously, hydrogen from the melt diffused into the air bubble. The changes in composition were used to estimate the rate of change in composition of the interior atmosphere of a typical double oxide film defect of an estimated size. This suggested that double oxide film defects may quickly achieve an interior atmosphere that would consist of a mixture of mainly nitrogen and hydrogen, and that this atmosphere could exist for periods of time greater than the typical solidification times of light alloy castings. In other words, oxide film defects created during mould filling should persist into the solidified casting. In addition, SEM analysis of oxide film defects also suggested the presence of oxide whiskers, which seem to have formed during holding in the melt.