Atomic Dynamic Flow Games: Adaptive vs. Nonadaptive Agents

We propose a game model for selfish routing of atomic agents, who compete for use of a network to travel from their origins to a common destination as quickly as possible. We follow a frequently used rule that the latency an agent experiences on each edge is a constant transit time plus a variable waiting time in a queue. A key feature that differentiates our model from related ones is an edge-based tie-breaking rule for prioritizing agents in queueing when they reach an edge at the same time. We study both nonadaptive agents (each choosing a one-off origin–destination path simultaneously at the very beginning) and adaptive ones (each making an online decision at every nonterminal vertex they reach as to which next edge to take). On the one hand, we constructively prove that a (pure) Nash equilibrium (NE) always exists for nonadaptive agents and show that every NE is weakly Pareto optimal and globally first-in first-out. We present efficient algorithms for finding an NE and best responses of nonadaptive agents. On the other hand, we are among the first to consider adaptive atomic agents, for which we show that a subgame perfect equilibrium (SPE) always exists and that each NE outcome for nonadaptive agents is an SPE outcome for adaptive agents but not vice versa.

Hybrid Processing Combining Electrostatic Levitation and Laser Heating: Application to Terrestrial Analogues of Asteroid Materials

Electrostatic levitation combined with laser heating is becoming a mature technique that has been used for several fundamental and applied studies in fluid and materials sciences (synthesis, property determination, solidification studies, atomic dynamic studies, etc.). This is attributable to the numerous processing conditions (containerless, wide heating temperature range, cooling rates, atmospheric compositions, etc.) that levitation and radiative heating offer, as well as to the variety of diagnostics tools that can be used. In this paper, we describe the facility, highlighting the combined advantages of electrostatic levitation and laser processing. The various capabilities of the facility are discussed and are exemplified with the measurements of the density of selected iron-nickel alloys taken over the liquid phase.

Shear deformation in TiAl: Atomic dynamic and static simulations

The dynamic shear deformation process and the related stacking fault transitions in TiAl have been systematically investigated using both the molecular dynamics and ab initio methods. The details of the dislocation initiation and microstructural evolution are presented, and the concomitant potential energy variation and the radial distribution functions have been analyzed. The results show, interestingly, that some deformation-induced hexagonal close-packed (hcp) structures are metastable, and that a higher velocity field promotes more hcp segments. The phenomena are interpreted based on ab initio calculations of the detailed energy variation at the different fault transition stages, i.e., superlattice intrinsic stacking fault (SISF) → TWIN, SISF → hcp, and hcp → TWIN. The intrinsic factor that governs the deformation process is discussed. The results promote new understanding of the stress-induced interfaces and dislocation behaviors in experimental observations.