Analysis of Liquefaction at a Bridge Site in the 2014 Napa Earthquake

2017 ◽  
Author(s):  
Kathleen M. Darby ◽  
Martin W. McIlroy ◽  
Ross W. Boulanger ◽  
Jason T. DeJong
Keyword(s):  
Bridge Site

Coverage and Stability of NHx Terminated Cobalt and Ruthenium Surfaces: a First Principles Investigation

2019 ◽  
Author(s):  
Ji Liu ◽  
Michael Nolan
Keyword(s):  
Metal Surfaces ◽  
High Vacuum ◽  
Atomic Layer ◽  
Nitrogen Plasma ◽  
Operating Conditions ◽  
Ultra High Vacuum ◽  
Bridge Site ◽  
Stable Surface ◽  
Saturation Coverage ◽  
The Stability

<div>In the atomic layer deposition (ALD) of Cobalt (Co) and Ruthenium (Ru) metal using nitrogen plasma, the structure and composition of the post N-plasma NHx terminated (x = 1 or 2) metal surfaces are not well known but are important in the subsequent metal containing pulse. In this paper, we use the low-index (001) and (100) surfaces of Co and Ru as models of the metal polycrystalline thin films. The (001) surface with a hexagonal surface structure is the most stable surface and the (100) surface with a zigzag structure is the least stable surface but has high reactivity. We investigate the stability of NH and NH2 terminations on these surfaces to determine the saturation coverage of NHx on Co and Ru. NH is most stable in the hollow hcp site on (001) surface and the bridge site on the (100) surface, while NH2 prefers the bridge site on both (001) and (100) surfaces. The differential energy is calculated to find the saturation coverage of NH and NH2. We also present results on mixed NH/NH2-terminations. The results are analyzed by thermodynamics using Gibbs free energies (ΔG) to reveal temperature effects on the stability of NH and NH2 terminations. Ultra-high vacuum (UHV) and standard ALD</div><div>operating conditions are considered. Under typical ALD operating conditions we find that the most stable NHx terminated metal surfaces are 1 ML NH on Ru (001) surface (350K-550K), 5/9 ML NH on Co (001) surface (400K-650K) and a mixture of NH and NH2 on both Ru (100) and Co (100) surfaces.</div>

scholarly journals Hydrogen Atom and Molecule Adsorptions on FeCrAl (100) Surface: A First-Principle Study

2021 ◽  
Vol 9 ◽  
Author(s):  
Xiaojing Li ◽  
Yu Ma ◽  
Wenzhong Zhou ◽  
Zhao Liu
Keyword(s):  
Hydrogen Atom ◽  
Hydrogen Embrittlement ◽  
First Principle ◽  
Light Water Reactors ◽  
Bridge Site ◽  
Premature Failure ◽  
Hydrogen Interaction ◽  
Good Guide ◽  
Water Reactors ◽  
High Irradiation

FeCrAl alloys are promising accident-tolerant fuel (ATF) cladding materials for applications in light water reactors (LWRs). Despite the excellent mechanical and antioxidation properties, this series of iron-based alloys has poor hydrogen embrittlement (HE) resistance due to the strong hydrogen uptaking ability. The hydrogen embrittlement effect can cause the degradation and premature failure of the material, and this effect can be enhanced by the high-temperature/high-pressure/high-irradiation environment in reactors. So, the potential danger should be taken seriously. In this paper, we have studied the hydrogen atom and molecule adsorptions on both Fe (100) and FeCrAl (100) surfaces to discover how the hydrogen atom and molecule (H/H2) interact with the Fe and FeCrAl (100) surface in the first place. The results show that there are strong element effects on the FeCrAl surface. The Al atom itself has no interaction with hydrogen. When the Al atom is beside the Fe atom, this Fe atom has a slightly lower interaction with hydrogen. However, the Al atom beside the Cr atom will enhance the hydrogen interaction with this Cr atom. On the other hand, when the Cr atom is beside the Fe atom, these two atoms (Fe–Cr bridge site) can reduce the interactions with H. In addition, when two Cr and two Fe atoms together make a four-fold site (FF site), the two Cr atoms can increase the interaction of the two Fe atoms with H. The element effects discovered can be a good guide for making hydrogen prevention coatings.

Hydrodynamic Impact on Pearl River Estuary from HZM Bridge

2014 ◽  
Vol 488-489 ◽  
pp. 475-478 ◽  
Author(s):  
Jie He ◽  
Wen Jie Xin
Keyword(s):  
River Estuary ◽  
Pearl River Estuary ◽  
Tidal Range ◽  
Pearl River ◽  
Bridge Site ◽  
Hydrodynamic Impact ◽  
The Pearl River Estuary ◽  
The Pearl River ◽  
Hydrodynamic Environment ◽  
Hydrodynamic Influence

The HZM(Hongkong-Zhuhai-Macao) bridge connects Hongkong, Zhuhai and Macao district, and it strctchs across the Pearl River estuary. A lot of piers and three large artifical islands would have some impact on the hydrodynamic environment in the Pear River estuary. In this paper, a 2D tidal current numerical model is introduced to simulate the hydrodynamic impact from the HZM brdige. The simulated results show that the Hydrodynamic influence is concentrated on the 5.0 km range from downstream to upstream nearby the navigation zone and the 1.0 km range of bridge site in not-navigation zone, and the tidal range reduction is limited 0.03m and the tidal prism reduction is not more than 1% in the Lingding Sea after the HZM bridge constructed. Therefore, the HZM bridge has little influence on the distribution of hydrodynamic environment in the Pearl River estuary.

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