Global Existence and Large-Time Behavior of Solutions to the Three-Dimensional Equations of Compressible Magnetohydrodynamic Flows

The three-dimensional equations of compressible magnetohydrodynamic isentropic flows are considered. An initial-boundary value problem is studied in a bounded domain with large data. The existence and large-time behavior of global weak solutions are established through a three-level approximation, energy estimates, and weak convergence for the adiabatic exponent $\gamma>\frac32$ and constant viscosity coefficients

Phylogenetic and Pathotypical Analysis of Two Virulent Newcastle Disease Viruses Isolated from Domestic Ducks in China

Two velogenic Newcastle disease viruses (NDV) obtained from outbreaks in domestic ducks in China were characterized in this study. Phylogenetic analysis revealed that both strains clustered with the class II viruses, with one phylogenetically close to the genotype VII NDVs and the other closer to genotype IX. The deduced amino acid sequence of the cleavage site of the fusion (F) protein confirmed that both isolates contained the virulent motif 112RRQK/RRF117 at the cleavage site. The two NDVs had severe pathogenicity in fully susceptible chickens, resulting in 100% mortality. One of the isolates also demonstrated some pathogenicity in domestic ducks. The present study suggests that more than one genotype of NDV circulates in domestic ducks in China and viral transmission may occur among chickens and domestic ducks

Cathode supports of SOFCs with a hierarchical pore structure

Cathode-supported SOFCs are attractive for the potential utilization of hydrocarbons as fuels to generate electricity because Cu-based anodes can be used to deal with coke formation in the Ni-base anodes. However, Cu-based anodes cannot be used in anode-supported SOFCs because the high sintering temperatures (above 1350 °C) required for the formation of a dense electrolyte film may melt the Cu-based anodes. Compared with anode materials, cathode materials show higher sinterability, which leads to a low porosity of the supporting cathodes and in turn high gas diffusion resistance within the cathodes. To get around this problem, a novel supporting cathode with efficient gas diffusion channels will be developed in this study in order to achieve high performances in power generation

A Controlled-Type Zvs Technique Without Auxiliary Components For The Low Power Dc/Ac Inverter

This paper proposes a soft switching technique for dc/ac inverters, by using duty cycle and frequency modulation. Zero voltage switching (ZVS) is achieved through controlling the inductor current bidirectional in every switching cycle. This technique requires no additional resonant components and can be employed for various low power applications on conventional full-bridge and half-bridge inverter topologies. Three different current mode control schemes are derived from the basic theory of the proposed technique. They are referred to as boundary current mode (BCM), variable hysteresis current mode (VHCM), and constant hysteresis current mode (CHCM) in this paper and their advantages and disadvantages are compared. Simulation and experimental results demonstrate the feasibilities of the proposed soft-switching technique and its control schemes. © 1986-2012 IEEE

A nanocatalyst network for electrochemical reduction of CO2 over microchanneled solid oxide electrolysis cells

A nanocatalyst network has been successfully prepared over the internal surface of Ni-based cathode support with a microchanneled structure via an impregnation process. Through numerous microchannels within the cathode support, a catalyst precursor solution was effectively delivered to the interface between cathode and electrolyte, resulting in the formation of the nanocatalyst network in the cathode reaction zone and therefore decreased degradation rate during CO 2 electrolysis. After four coatings, the robust nanocatalyst network was formed to produce the least degradation, and further catalyst coatings caused concentration polarization

Steam reforming of acetic acid over nickel-based catalysts: The intrinsic effects of nickel precursors on behaviors of nickel catalysts

© 2018 Elsevier B.V. The paper investigated the effects of various nickel precursors (Ni(NO3)2, NiCl2, NiSO4, Ni(CH3COO)2, Ni(NH2SO3)2) on the catalytic behaviors of Ni/Al2O3catalysts in steam reforming of acetic acid, aiming to understand the fundamental influences of nickel metal precursors. The catalysts were characterized with TPR, TPO, TPR-MS, TPO-MS, XRD, TG-MS, FT-IR, FT-Raman, BET method, element analysis, TEM and SEM. The results revealed the substantial influence of the nickel precursors on properties of Ni/Al2O3catalysts. The use of NiSO4and Ni(NH2SO3)2as nickel precursors led to the low activities of the catalysts, due to the formation of Ni3S2during reduction of the catalysts with hydrogen. The sulfur species were removed in the form of SO2during the calcination of the catalysts precursors in air and in the form of H2S during the reduction of the calcined catalyst in hydrogen. NiCl2/Al2O3catalyst showed a negligible activity as the chlorine poisoned the catalyst and was difficult to be removed via calcination. Furthermore, chlorine could accelerate sintering of alumina. In comparison, Ni(CH3COO)2as nickel precursor could effectively suppress the formation of NiAl2O4. Ni(CH3COO)2/Al2O3catalyst showed comparable activity to that of Ni(NO3)2/Al2O3, but the resistivity towards coking was higher. In addition, the coke species produced over the catalysts have both large and small aromatic ring systems with the morphology of both amorphous and fibrous structures

Effect of NiO/YSZ cathode support pore structure on CO2 electrolysis via solid oxide electrolysis cells

Gas diffusion within supporting cathodes of solid oxide electrolysis cells (SOECs) plays an important role in CO2electrolysis process. This study has investigated the effect of cathode pore structure on gas diffusion during CO2electrolysis. The cathode pore structure was adjusted by applying the different amounts of pore former during cathode preparation. The more pore former added produced the higher porosity of cathode and the higher limiting current density. High limiting current densities are beneficial to diminish or even eliminate gas diffusion limitation in practical applications, where the electrolysis is expected to be operated at low CO2concentrations to increase CO2conversion. An advanced impedance spectroscopy study is performed to confirm the limiting current density measured according to current-voltage curves. It was revealed that CO2electrolysis performance is greatly affected by gas diffusion, which is determined by the employed cathode pore structure