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[en] Highlights: • Hydrate reservoir model with three sublayers was built to replicate 2017 Shenhu test. • Long-term simulations were conducted to predict gas production behavior in reservoir. • Contributions of each sublayer to the total gas production were fully investigated. • Mechanisms of permeability enhancement for enhanced gas recovery were examined. • Application priority was recommended for the utilization of permeability enhancement. In 2017, an offshore methane hydrate production test was successfully conducted at well SHSC-4 in the Shenhu Area of the South China Sea, but the long-term gas production behavior is still unknown and requires further investigation. In this study, a multi-layered methane hydrate reservoir model with three sublayers of the hydrate-bearing layer (HBL), three-phase layer (TPL), and free gas layer (FGL) was built based on the actual geological conditions at this site, and a short-term simulation was initially conducted to verify the validity of the reservoir model. Afterwards, the long-term simulations were conducted to predict the hydrate dissociation and gas production behaviors in the reservoir and investigate the contributions of each sublayer to the total gas production, and the effects of the intrinsic permeability of each sublayer on the gas production were fully examined. The simulation results indicated that the average gas production rate (1.83 × 103 ST m3/d) was less than half of that confirmed during the 2017 Shenhu production test (5.15 × 103 ST m3/d). The majority of the total gas production originated from the free gas in the FGL (56.5%), followed by the methane gas released from hydrate dissociation in the HBL (24.1%), and the TPL contributed the least to the gas recovery (19.4%). In addition, if the method of permeability enhancement was applied to the methane hydrate reservoir at well SHSC-4, the gas production could be greatly promoted, but the mechanisms were different. Finally, the following application priority was recommended: HBL > FGL > TPL.
[en] Materials irradiated in the target/blanket region of the Accelerator Production of Tritium (APT) system will contain significantly more hydrogen and helium, for any given displacements per atom (dpa), than typically found in materials irradiated in a fission reactor. The individual effects of helium and hydrogen implantation and displacement damage on structural materials are relatively well established. Helium will increase the strength, decrease the ductility, reduce the creep and stress rupture properties, decrease the fatigue life and weldability, and promote swelling. Hydrogen will also adversely effect the mechanical properties and promote premature fracture along metallurgical interfaces. Displacement damage generally increases the strength and decreases the ductility of single-phase metals and alloys. The adverse effects of hydrogen and helium implantation may couple with displacement damage to limit component lifetime in the target/blanket region of the APT system. This paper provides a technical basis to rationalize potential synergistic effects among displacement damage and the hydrogen and helium embrittlement processes and suggests that such synergistic effects may be of significant importance to component performance in intense spallation neutron sources
[en] We examine the melting of commensurate and incommensurate vortex lattices interacting with square pinning arrays through the use of numerical simulations. For weak pinning strength in the commensurate case we observe an order-order transition from a commensurate square vortex lattice to a triangular floating solid phase as a function of temperature. This floating solid phase melts into a liquid at still higher temperature. For strong pinning there is only a single transition from the square pinned lattice to the liquid state. For strong pinning in the incommensurate case, we observe a multistage melting in which the interstitial vortices become mobile first, followed by the melting of the entire lattice, consistent with recent imaging experiments. The initial motion of vortices in the incommensurate phase occurs by an exchange process of interstitial vortices with vortices located at the pinning sites. We have also examined the vortex melting behavior for higher matching fields and find that a coexistence of a commensurate pinned vortex solid with an interstitial vortex liquid occurs while at higher temperatures the entire vortex lattice melts. For triangular arrays at incommensurate fields higher than the first matching field we observe that the initial vortex motion can occur through a correlated ring excitation where a number of vortices can rotate around a pinned vortex. We also discuss the relevance of our results to recent experiments of colloidal particles interacting with periodic trap arrays
[en] The successful prediction of the conditions under which nucleation occurs in metals, as a result of the high concentrations of vacancies and interstitial atoms (and gas atoms) present in reactor environments, has been accomplished by (1) generalizing homogeneous nucleation theory to account for nucleation of matter (i.e., vacancies) in the presence of its antimatter (i.e., interstitials), (2) further generalizing the theory to account for the effects of both trapped and soluble gas, and (3) modifying the theory to describe interstitial loop formation and including the effects of external stress
[en] In this paper the authors present their findings on the isolation and characterisation, including sequence, of two forms of inhibin from bovine follicular fluid (bFF) and the subsequent development of a radioimmunoassay (RIA) procedure which is applicable to follicular fluid and serum. (Auth.)