4,028 research outputs found
Optimal measurements to access classical correlations of two-qubit states
We analyze the optimal measurements accessing classical correlations in
arbitrary two-qubit states. Two-qubit states can be transformed into the
canonical forms via local unitary operations. For the canonical forms, we
investigate the probability distribution of the optimal measurements. The
probability distribution of the optimal measurement is found to be centralized
in the vicinity of a specific von Neumann measurement, which we call the
maximal-correlation-direction measurement (MCDM). We prove that for the states
with zero-discord and maximally mixed marginals, the MCDM is the very optimal
measurement. Furthermore, we give an upper bound of quantum discord based on
the MCDM, and investigate its performance for approximating the quantum
discord.Comment: 8 pages, 3 figures, version accepted by Phys. Rev.
Collapse simulation of a typical super-tall RC frame-core tube building exposed to extreme fire
The previous fire accidents proofed that reinforced concrete (RC) structures may experience progressive collapse subjected to extreme fires. In consequence, the study on the extreme fire-induced progressive collapse of RC structures is important for the safety of buildings. However, limited study has been performed on the extreme fire-induced progressive collapse of super-tall buildings. In this work, a finite element (FE) model and the corresponding elemental deactivation technology is proposed to simulate the extreme fire-induced progressive collapse of a typical super-tall RC frame-core tube building. The simulation discovered that the collapse of the building is initiated by the flexural failure of perimeter columns because of the thermal expansion of the floor system. The mechanism that discovered can provide a reference for related research of the fire safety of RC buildings
Cathodoluminescence and Cross-sectional Transmission Electron Microscopy Studies for Deformation Behaviors of GaN Thin Films Under Berkovich Nanoindentation
In this study, details of Berkovich nanoindentation-induced mechanical deformation mechanisms of metal-organic chemical-vapor deposition-derived GaN thin films have been systematic investigated with the aid of the cathodoluminescence (CL) and the cross-sectional transmission electron microscopy (XTEM) techniques. The multiple “pop-in” events were observed in the load-displacement (P–h) curve and appeared to occur randomly by increasing the indentation load. These instabilities are attributed to the dislocation nucleation and propagation. The CL images of nanoindentation show very well-defined rosette structures with the hexagonal system and, clearly display the distribution of deformation-induced extended defects/dislocations which affect CL emission. By using focused ion beam milling to accurately position the cross-section of an indented area, XTEM results demonstrate that the major plastic deformation is taking place through the propagation of dislocations. The present observations are in support to the massive dislocations activities occurring underneath the indenter during the loading cycle. No evidence of either phase transformation or formation of micro-cracking was observed by means of scanning electron microscopy and XTEM observations. We also discuss how these features correlate with Berkovich nanoindentation produced defects/dislocations structures
Fast List Decoding of High-Rate Polar Codes
Due to the ability to provide superior error-correction performance, the
successive cancellation list (SCL) algorithm is widely regarded as one of the
most promising decoding algorithms for polar codes with short-to-moderate code
lengths. However, the application of SCL decoding in low-latency communication
scenarios is limited due to its sequential nature. To reduce the decoding
latency, developing tailored fast and efficient list decoding algorithms of
specific polar substituent codes (special nodes) is a promising solution.
Recently, fast list decoding algorithms are proposed by considering special
nodes with low code rates. Aiming to further speedup the SCL decoding, this
paper presents fast list decoding algorithms for two types of high-rate special
nodes, namely single-parity-check (SPC) nodes and sequence rate one or
single-parity-check (SR1/SPC) nodes. In particular, we develop two classes of
fast list decoding algorithms for these nodes, where the first class uses a
sequential decoding procedure to yield decoding latency that is linear with the
list size, and the second further parallelizes the decoding process by
pre-determining the redundant candidate paths offline. Simulation results show
that the proposed list decoding algorithms are able to achieve up to 70.7\%
lower decoding latency than state-of-the-art fast SCL decoders, while
exhibiting the same error-correction performance.Comment: 13 pages, 8 figure
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