33,930 research outputs found
Recommended from our members
Experimental and computational investigation of confined laser-induced breakdown spectroscopy
This paper presents an experimental and computational study on laser-induced breakdown spectroscopy (LIBS) for both unconfined flat surface and confined cavity cases. An integrated LIBS system is employed to acquire the shockwave and plasma plume images. The computational model consists of the mass, momentum, and energy conservation equations, which are necessary to describe shockwave behaviors. The numerical predictions are validated against shadowgraphic images in terms of shockwave expansion and reflection. The three-dimensional (3D) shockwave morphology and velocity fields are displayed and discussed
DISCHARGE OXIDE STORAGE CAPACITY AND VOLTAGE LOSS IN LI-AIR BATTERY
Air cathodes, where oxygen reacts with Li ions and electrons with discharge oxide stored in their pore structure, are often considered as the most challenging component in nonaqueous Lithium-air batteries. In non-aqueous electrolytes, discharge oxides are usually insoluble and hence precipitate at local reaction site, raising the oxygen transport resistance in the pore network. Due to their low electric conductivity, their presence causes electrode passivation. This study aims to investigate the air cathode's performance through analytically obtaining oxygen profiles, modeling electrode passivation, evaluating the transport polarization raised by discharge oxide precipitate, and developing analytical formulas for insoluble Li oxides storage capacity. The variations of cathode quantities, including oxygen content and temperature, are evaluated and related to a single dimensionless parameter - the Damköhler Number (Da). An approximate model is developed to predict discharge voltage loss, along with validation against two sets of experimental data. Air cathode properties, including tortuosity, surface coverage factor and the Da number, and their effects on the cathode's capacity of storing Li oxides are formulated and discussed
Optical spectroscopy study on single crystalline LaFeAsO
Millimeter-sized single crystals of LaFeAsO were grown from NaAs flux and the
in-plane optical properties were studied over a wide frequency range. A sizable
electronic correlation effect was indicated from the analysis of the
free-carrier spectral weight. With decreasing temperature from 300 K, we
observed a continuous suppression of the spectral weight near 0.6 eV. But a
spin-density-wave gap formation at lower energy scale was seen only in the
broken-symmetry state. We elaborate that both the itinerancy and local spin
interactions of Fe\emph{3d} electrons are present for the FeAs-based systems;
however, the establishment of the long-range magnetic order at low temperature
has a dominantly itinerant origin.Comment: 4 figures, 5 page
Average distance in a hierarchical scale-free network: an exact solution
Various real systems simultaneously exhibit scale-free and hierarchical
structure. In this paper, we study analytically average distance in a
deterministic scale-free network with hierarchical organization. Using a
recursive method based on the network construction, we determine explicitly the
average distance, obtaining an exact expression for it, which is confirmed by
extensive numerical calculations. The obtained rigorous solution shows that the
average distance grows logarithmically with the network order (number of nodes
in the network). We exhibit the similarity and dissimilarity in average
distance between the network under consideration and some previously studied
networks, including random networks and other deterministic networks. On the
basis of the comparison, we argue that the logarithmic scaling of average
distance with network order could be a generic feature of deterministic
scale-free networks.Comment: Definitive version published in Journal of Statistical Mechanic
- …