8,456 research outputs found
Luby Transform Coding Aided Bit-Interleaved Coded Modulation for the Wireless Internet
Bit-Interleaved Coded Modulation using Iterative Decoding (BICM-ID) is amalgamated with Luby Transform (LT) coding. The resultant joint design of the physical and data link layer substantially improves the attainable Bit Error Rate (BER) performance. A Cyclic Redundancy Check (CRC) combined with a novel Log-Likelihood Ratio (LLR) based packet reliability estimation method is proposed for the sake of detecting and disposing of erroneous packets. Subsequently, bit-by-bit LT decoding is proposed, which facilitates a further BER improvement at a lower number of BICM-ID iterations. Finally, we revisit the pseudo random generator function used for designing the LT generator matrix
Ultrafast Molecular Imaging by Laser Induced Electron Diffraction
We address the feasibility of imaging geometric and orbital structure of a
polyatomic molecule on an attosecond time-scale using the laser induced
electron diffraction (LIED) technique. We present numerical results for the
highest molecular orbitals of the CO2 molecule excited by a near infrared
few-cycle laser pulse. The molecular geometry (bond-lengths) is determined
within 3% of accuracy from a diffraction pattern which also reflects the nodal
properties of the initial molecular orbital. Robustness of the structure
determination is discussed with respect to vibrational and rotational motions
with a complete interpretation of the laser-induced mechanisms
Regional Capital Mobility in China: 1978-2006
We examine cross-region capital mobility in China and track how the degree of mobility has changed over time. The effects of fiscal and redistributive activities of different levels of government in China on private capital mobility are taken into account. Our results indicate that there was a significant improvement in capital mobility over time in China, particularly for private capital in the more developed regions. The central and provincial governments, via their taxation, spending, and transfers, loosen the relationship between private saving and investment and appear to promote capital mobility, particularly for less developed regions. There are considerable differences between more and less developed regions in terms of the degree of capital market integration and the improvement in capital mobility over time. The results have important policy implications on global re-balancing as well as regional development gap and risk-sharing within China.Feldstein-Horioka; Chinese cross-region capital mobility; saving-investment relationship; Chinese capital market integration
Structural, optical and electrical conductivity properties of stannite Cu₂ZnSnS₄
A precursor powder was obtained from drying the solutions of a mixture of different ratios of Cu, Zn and Sn chloride and thiourea. The Cu2ZnSnS4 (CZTS) samples were prepared from thermal decomposition of the corresponding precursors in vacuum, and were then characterized using scanning emission microscopy, energy dispersive x-ray analysis, x-ray powder diffraction and Raman scatterin
Combined Global and Local Search for the Falsification of Hybrid Systems
In this paper we solve the problem of finding a trajectory that shows that a
given hybrid dynamical system with deterministic evolution leaves a given set
of states considered to be safe. The algorithm combines local with global
search for achieving both efficiency and global convergence. In local search,
it exploits derivatives for efficient computation. Unlike other methods for
falsification of hybrid systems with deterministic evolution, we do not
restrict our search to trajectories of a certain bounded length but search for
error trajectories of arbitrary length
Laser induced electron diffraction: a tool for molecular orbital imaging
We explore the laser-induced ionization dynamics of N2 and CO2 molecules
subjected to a few-cycle, linearly polarized, 800\,nm laser pulse using
effective two-dimensional single active electron time-dependent quantum
simulations. We show that the electron recollision process taking place after
an initial tunnel ionization stage results in quantum interference patterns in
the energy resolved photo-electron signals. If the molecule is initially
aligned perpendicular to the field polarization, the position and relative
heights of the associated fringes can be related to the molecular geometrical
and orbital structure, using a simple inversion algorithm which takes into
account the symmetry of the initial molecular orbital from which the ionized
electron is produced. We show that it is possible to extract inter-atomic
distances in the molecule from an averaged photon-electron signal with an
accuracy of a few percents
Structural properties and variable-range hopping conductivity of Cu₂SnS₃
In the present work, we investigated the elemental composition, structural and electrical properties of Cu₂SnS₃ (CTS) ternary semiconductor synthesized by the pyrolytic decomposition of the precursors in vacuu
Electrochemical copper recovery from galvanic sludge
The feasibility of recovering copper from electronic industrial waste mud (galvanic sludge) using a combination of leaching and electrowinning has been examined. Leaching with sulfuric acid was found to be the most efficient and cost-effective way of extracting the copper from the sludge, and the optimum acid concentration and time were determined. The copper was then extracted by electrowinning in a batch recirculation electrochemical reactor (Porocell™) employing a three-dimensional carbon felt cathode. The influence of applied current, flow rate and the presence of other metal ion contaminates on the rate and current efficiency of copper electrowinning was investigated. An analysis of the experimental data showed that the current efficiency was lower than unity even though the limiting current for copper deposition was not exceeded. This low current efficiency was attributed to the occurrence of a side reaction, most likely the reduction of dissolved oxygen or oxygen-induced corrosion. The influence of this side reaction can be minimized by operating at relatively high currents and low flow rates
- …