Cooperative standing-horizontalstanding reentrant transition for numerous solid particles under external vibration

We report the collective behavior of numerous plastic bolt-like particles exhibiting one of two distinct states, either standing stationary or horizontal accompanied by tumbling motion, when placed on a horizontal plate undergoing sinusoidal vertical vibration. Experimentally, we prepared an initial state in which all of the particles were standing except for a single particle that was placed at the center of the plate. Under continuous vertical vibration, the initially horizontal particle triggers neighboring particles to fall over into a horizontal state through tumbling-induced collision, and this effect gradually spreads to all of the particles, i.e., the number of horizontal particles is increased. Interestingly, within a certain range of vibration intensity, almost all of the horizontal particles revert back to standing in association with the formation of apparent 2D hexagonal dense-packing. Thus, phase segregation between high and low densities, or crystalline and disperse domains, of standing particles is generated as a result of the reentrant transition. The essential features of such cooperative dynamics through the reentrant transition are elucidated with a simple kinetic model. We also demonstrate that an excitable wave with the reentrant transition is observed when particles are situated in a quasi-one-dimensional confinement on a vibrating plate

Direct determination of Burgers vector sense and magnitude of elementary dislocations by synchrotron white x-ray topography

The x-ray topography by using highly coherent beam obtained at third-generation synchrotron facilities can provide higher spatial resolution and higher lattice-distortion sensitivity than those by former-generation facilities. Here, we report the direct determination of the Burgers vector senses and magnitudes of elementary dislocations in a high-quality silicon carbide single crystal using white x-ray section topography with a long sample-to-film distance. Our data strongly indicate that there are very weak but extraordinarily long-range elastic interactions between elementary screw dislocations. Those interactions govern dislocation-propagation behavior and the distribution of dislocations. Moreover, we found that white x-ray projection topography with a long sample-to-film distance can also be a powerful tool to effectively examine the detailed structure of elementary dislocations in single crystals

ヒヘイコウ ユラギ ガ ツクリダス パターン ダイナミクス : ジツクウカン モデル ニヨル ケンキュウ

博士(工学)同志社大学微生物から人類まで、地球上のすべての生命体は、非平衡開放条件下で生命活動を維持している。生物が織りなすさまざまな生命現象の基礎となり、生物を生物たらしめている本質的なものは、非平衡開放条件下での「自己組織化現象」や 「時間発展的な自己秩序化現象」と言える。本論文は、生命体そのものではなく、その自己組織や自己秩序化についての実空間の簡単なモデル系を取り上げて、研究を行った結果をまとめたものである。From microorganisms to human beings, all living organisms on the earth maintain life activities under non-equilibrium open conditions. Self-organizing phenomena or time-evolving self-ordering phenomena under non-equilibrium open conditions are essential things that serve as the foundation of various life phenomena woven by living things and that keep living things as creatures. By taking a simple model system of real space about its self-organization and self-ordering, this paper summarized the results of research processed