Optimization of Dimples in Microchannel Heat Sink with Impinging Jets—Part B: the Influences of Dimple Height and Arrangement

The combination of a microchannel heat sink with impinging jets and dimples (MHSIJD) can effectively improve the flow and heat transfer performance on the cooling surface of electronic devices with very high heat fluxes. Based on the previous work by analysing the effect of dimple radius on the overall performance of MHSIJD, the effects of dimple height and arrangement were numerically analysed. The velocity distribution, pressure drop, and thermal performance of MHSIJD under various dimple heights and arrangements were presented. The results showed that: MHSIJD with higher dimples had better overall performance with dimple radius being fixed; creating a mismatch between the impinging hole and dimple can solve the issue caused by the drift phenomenon; the mismatch between the impinging hole and dimple did not exhibit better overall performance than a well-matched design

Competitive Outcomes and Endogenous Coalition Formation in an n-Person Game

In this paper we study competitive outcomes and endogenous coalition formation in a cooperative n-person transferable utility (TU) game from the viewpoint of general equilibrium theory.For any given game, we construct a competitive exchange coalition production economy corresponding to the game. First, it is shown that the full core of a TU game is not empty if and only if the completion of the game is balanced.The full core is defined free of any particular coalition structure and the coalitions of the game emerge endogenously from the full core.Second, it is shown that the full core of a completionbalanced general TU game coincides with the set of equilibrium payoff vectors of its corresponding economy and that the coalition structures of the game are endogenously determined by the equilibrium outcomes of the economy.As a consequence, the core of a balanced general TU game coincides with the set of equilibrium payoff vectors of its corresponding economy.game theory;cooperative games;general equilibrium

Unraveling the Cationic and Anionic Redox Reactions in a Conventional Layered Oxide Cathode

Increasing interest in high-energy lithium-ion batteries has triggered the demand to clarify the reaction mechanism in battery cathodes during high-potential operation. However, the reaction mechanism often involves both transition-metal and oxygen activities that remain elusive. Here we report a comprehensive study of both cationic and anionic redox mechanisms of LiNiO2 nearly full delithiation. Selection of pure LiNiO2 removes the complication of multiple transition metals. Using combined X-ray absorption spectroscopy, resonant inelastic X-ray scattering, and operando differential electrochemical mass spectrometry, we are able to clarify the redox reactions of transition metals in the bulk and at the surface, reversible lattice oxygen redox, and irreversible oxygen release associated with surface reactions. Many findings presented here bring attention to different types of oxygen activities and metal-oxygen interactions in layered oxides, which are of crucial importance to the advancement of a Ni-rich layered oxide cathode for high capacity and long cycling performance

Dynamics of moving bubbles in single and binary component systems

Dynamics of a single bubble moving in a quiescent liquid is analyzed for single and binary component systems. The transport of energy and/or mass at thermodynamic-phase equilibrium governs the dynamics of the bubble at its interface

Thermal rectifier from deformed carbon nanohorns

We study thermal rectification in single-walled carbon nanohorns (SWNHs) by using non-equilibrium molecular dynamics (MD) method. It is found that the horns with the bigger top angles show larger asymmetric heat transport due to the larger structural gradient distribution. This kind of gradient behavior can be further adjusted by applying external strain on the SWNHs. After being carefully elongated along the axial direction, the thermal rectification in the elongated SWNHs can become more obvious than that in undeformed ones. The maximum rectification efficiency of SWNHs is much bigger than that of carbon nanotube intramolecular junctions.Comment: 3 figure