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The polymeric conformational effect on capacitive deionization performance of graphene oxide/polypyrrole composite electrode
Exploitation of novel faradic materials is an alternative implementation for solving the problem of poor specific electrosorption capacity that conventional carbon materials are encountered in capacitive deionization. Particularly, composite electrode is just a suitable choice because of its potentially high ion-storage ability. Herein, a cyclic voltammetric treatment method with different low limit of potential window was used to manipulate the polymeric conformation and doping level of graphene oxide/polypyrrole (GO/PPy) composite electrode. Based on it, the effect of polymeric structure on the electrosorption performance was systematically studied. When the low limit of potential window is shifted negatively enough, the irreversible polymeric conformational shrinks of GO/PPy are promoted, which not only hinders the insertion process of ions, but also decreases the doping level of polymer due to the intensive interchain-action produced by more entangled polymeric chain. Thus, the number of intercalated ions should decrease, which is expressed by electrochemical impedance spectroscopy (EIS) results and is proportional to the electrosorption capacity of GO/PPy composite electrode in membrane capacitive deionization (MCDI) process. Our work suggests that the less packing density, higher doping level and more charge delocalization on PPy backbone in electrode are beneficial to enhance its capacitive deionization performance
Antenna array optimisation using semidefinite programming for cellular communications from HAPs
Array pattern optimisation based on semidefinite programming (SDP) is proposed to improve the coverage performance of cellular communications from High Altitude Platforms (HAPs). This optimisation, when applied to a linear vertical array of N omnidirectional antenna elements, allows a coverage performance better than that of an array of N narrowbeam aperture antennas forming hexagonal cells on the ground. In addition to the performance enhancement, the HAP antenna payload can be significantly reduced
A study of physical processes for space radiation protection
The determination of stopping power for monatomic molecules and water vapor is addressed. Intermediate and low energy protons are considered
New model of calculating the energy transfer efficiency for the spherical theta-pinch device
Ion-beam-plasma-interaction plays an important role in the field of Warm
Dense Matter (WDM) and Inertial Confinement Fusion (ICF). A spherical theta
pinch is proposed to act as a plasma target in various applications including a
plasma stripper cell. One key parameter for such applications is the free
electron density. A linear dependency of this density to the amount of energy
transferred into the plasma from an energy storage was found by C. Teske. Since
the amount of stored energy is known, the energy transfer efficiency is a
reliable parameter for the design of a spherical theta pinch device. The
traditional two models of energy transfer efficiency are based on assumptions
which comprise the risk of systematical errors. To obtain precise results, this
paper proposes a new model without the necessity of any assumption to calculate
the energy transfer efficiency for an inductively coupled plasma device.
Further, a comparison of these three different models is given at a fixed
operation voltage for the full range of working gas pressures. Due to the
inappropriate assumptions included in the traditional models, one owns a
tendency to overestimate the energy transfer efficiency whereas the other leads
to an underestimation. Applying our new model to a wide spread set of operation
voltages and gas pressures, an overall picture of the energy transfer
efficiency results
Effects of Ru Substitution on Dimensionality and Electron Correlations in Ba(Fe_{1-x}Ru_x)_2As_2
We report a systematic angle-resolved photoemission spectroscopy study on
Ba(FeRu)As for a wide range of Ru concentrations (0.15
\emph{x} 0.74). We observed a crossover from two-dimension to
three-dimension for some of the hole-like Fermi surfaces with Ru substitution
and a large reduction in the mass renormalization close to optimal doping.
These results suggest that isovalent Ru substitution has remarkable effects on
the low-energy electron excitations, which are important for the evolution of
superconductivity and antiferromagnetism in this system.Comment: 4 pages, 4 figure
FFT-LB modeling of thermal liquid-vapor systems
We further develop a thermal LB model for multiphase flows. In the improved
model, we propose to use the FFT scheme to calculate both the convection term
and external force term. The usage of FFT scheme is detailed and analyzed. By
using the FFT algorithm spatiotemporal discretization errors are decreased
dramatically and the conservation of total energy is much better preserved. A
direct consequence of the improvement is that the unphysical spurious
velocities at the interfacial regions can be damped to neglectable scale.
Together with the better conservation of total energy, the more accurate flow
velocities lead to the more accurate temperature field which determines the
dynamical and final states of the system. With the new model, the phase diagram
of the liquid-vapor system obtained from simulation is more consistent with
that from theoretical calculation. Very sharp interfaces can be achieved. The
accuracy of simulation results are also verified by the Laplace law. The FFT
scheme can be easily applied to other models for multiphase flows.Comment: 34 pages, 21 figure
The perfect spin injection in silicene FS/NS junction
We theoretically investigate the spin injection from a ferromagnetic silicene
to a normal silicene (FS/NS), where the magnetization in the FS is assumed from
the magnetic proximity effect. Based on a silicene lattice model, we
demonstrated that the pure spin injection could be obtained by tuning the Fermi
energy of two spin species, where one is in the spin orbit coupling gap and the
other one is outside the gap. Moreover, the valley polarity of the spin species
can be controlled by a perpendicular electric field in the FS region. Our
findings may shed light on making silicene-based spin and valley devices in the
spintronics and valleytronics field.Comment: 6 pages, 3 figure
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