Emergence of energy-avoiding and energy-seeking behaviors in nonequilibrium dissipative quantum systems

A longstanding challenge in nonequilibrium thermodynamics is to predict the emergence of self-organized behaviors and functionalities typical of living matter. Despite the progress with classical complex systems, it remains far from obvious how to extrapolate these results down to the quantum scale. Here, we employ the paradigmatic master equation framework to establish that some lifelike behaviors and functionalities can indeed emerge in elementary dissipative quantum systems driven out of equilibrium. Specifically, we find both energy-avoiding (low steady dissipation) and energy-seeking behaviors (high steady dissipation), as well as self-adaptive shifts between these modes, in generic few-level systems. We also find emergent functionalities, namely, a self-organized thermal gradient in the system’s environment (in the energy-seeking mode) and an active equilibration against thermal gradients (in the energy-avoiding mode). Finally, we discuss the possibility that our results could be related to the concept of dissipative adaptation.

Chemical Supercritical Fluid Infiltration of Pyrocarbon with Thermal Gradients: Deposition Kinetics and Multiphysics Modeling

The chemical supercritical fluid infiltration process is a recent variation of the chemical vapor infiltration (CVI) process that allows rapid and efficient manufacturing of ceramic-matrix composites (CMCs), albeit still needing optimization. This article proposes a quantitative assessment of the process dynamics through experiments and modeling. The kinetics of carbon deposition were determined through two sets of experiments: CVD on a single filament at pressures between 10 and 50 bar and infiltration at pressures ranging between 50 and 120 bar. The CVI experiments were conducted under important thermal gradients and were interpreted using a model-based reconstitution of these gradients. We found that (i) the kinetic law has to incorporate the potential effect of the reverse reaction (i.e., etching of C by H2); (ii) the activation energy and pre-exponential factor both decrease with pressure up to 50 bar, then remain roughly constant, and (iii) although the apparent activation energy is modest, a favorable situation occurs in which an infiltration front builds up and travels from the hottest to the coldest part of the preform due to the presence of sufficient heat flux. A numerical simulation of the process, based on the solution of momentum, heat, and mass balance equations, fed with appropriate laws for the effective transfer properties of the porous medium and their evolution with infiltration progress, was performed and validated by comparing the simulated and actual infiltration profiles.

Annual and seasonal changes of the air temperature with altitude in the Upper Dades valley, High Atlas, Morocco

The purpose of this study is to determine the size of air temperature changes with altitude in the mountains of the arid zone, on the example of the Upper Dades valley (High Atlas, Morocco). The air temperature change with altitude was determined on the basis of 5 years data from three meteorological stations. The analysis was carried out on an annual and seasonal basis. The annual and daily variations of thermal gradients between pairs of stations were also determined. It was found that the average thermal gradient in the Upper Dades valley was -1.02°C per 100 m. The highest values of the thermal gradient occur in winter and the lowest in summer. In winter, the thermal gradient was characterized by the greatest variability. Minima of the daily variation of air temperature gradients were observed in early morning hours and maxima around midday. In the lower part of the valley, air temperature inversion frequently developed between 10 AM and 3 PM UTC. The obtained results show high thermal gradients in the mountains of the arid zone, with their annual amplitude increasing in the lower parts of the valley. The instantaneous values of the gradients were significantly modified by the supply of latent heat and the occurrence of dust storms. It has been shown that the advection factor plays an important role in shaping large gradient values. The study contains novel results of thermal gradient measurements in high mountains of arid zone.

Utilization of continental transforms in break-up: observations, models, and a potential link to magmatism

Reactivation of continental transform faults (hereafter; transforms) is identified herein as a significant factor in continental break-up, based on a global review of divergent margins and numerical modelling. Divergent margins that have reactivated transforms are characterized by linear and abrupt terminations of thick continental crust. Transforms represent some of the largest structures on Earth, and these megastructures represent major lithospheric weaknesses and are therefore prone to reactivation upon changes in the stress field, which typically occur during plate break-up. The blunt termination of the margins is consistent with observations of very limited pre-breakup lithospheric thinning of such margins. This mode of break-up appears to occur abruptly, and contrasts notably with highly tapered and slowly extended divergent margins. Magma leakage along transforms is well-known worldwide where divergence occurs across such features. This leakage may evolve to dike injections, further reducing the plate strength. We observe that many of the blunt margins we attribute to transform reactivation have been prone to above-normal magmatism and are marked by seaward dipping reflectors underlain by high-velocity lower crustal intrusions. The magmatism may be directly related to the separation of abruptly terminated margins, whereby the large resulting lateral thermal gradients trigger edge-driven convection and melt addition.Supplementary material at https://doi.org/10.6084/m9.figshare.c.5756724

Residual Stresses Control in Additive Manufacturing

Residual stresses are one of the primary causes for the failure of parts or systems in metal additive manufacturing (AM), since they easily induce crack propagation and structural distortion. Although the formation of residual stresses has been extensively studied, the core factors steering their development in AM have not been completely uncovered. To date, several strategies based on reducing the thermal gradients have been developed to mitigate the manifestation of residual stresses in AM; however, how to choose the optimal processing plan is still unclear for AM designers. In this regard, the concept of the yield temperature, related to the thermal deformation and the mechanical constraint, plays a crucial role for controlling the residual stresses, but it has not been duly investigated, and the corresponding approach to control stresses is also yet lacking. To undertake such study, a three-bar model is firstly used to illustrate the formation mechanism of the residual stress and its key causes. Next, an experimentally calibrated thermomechanical finite element model is used to analyze the sensitivity of the residual stresses to the scan pattern, preheating, energy density, and the part geometry and size, as well as the substrate constraints. Based on the numerical results obtained from this analysis, recommendations on how to minimize the residual stresses during the AM process are provided.

Consumer trait responses track change in resource supply along replicated thermal gradients

Rising temperatures may alter consumer diets through increased metabolic demand and altered resource availability. However, current theories assessing dietary shifts with warming do not account for a change in resource availability. It is unknown whether consumers will increase consumption rates or consume different resources to meet increased energy requirements and whether the dietary change will lead to associated variation in morphology and nutrient utilization. Here, we used populations of Gambusia affinis across parallel thermal gradients in New Zealand (NZ) and California (CA) to understand the influence of temperature on diets, morphology and stoichiometric phenotypes. Our results show that with increasing temperature in NZ, mosquitofish consumed more plant material, whereas in CA mosquitofish shifted towards increased consumption of invertebrate prey. In both regions, populations with plant-based diets had fuller guts, longer relative gut lengths, better-orientated mouths and reduced body elemental %C and N/P. Together, our results show multiple pathways by which consumers may alter their feeding patterns with rising temperatures, and they suggest that warming-induced changes to resource availability may be the principal determinant of which pathway is taken.