98 research outputs found
A Spatiotemporal-chaos-based Encryption Having Overall Properties Considerably Better Than Advanced Encryption Standard
Spatiotemporal chaos of a two-dimensional one-way coupled map lattice is used
for chaotic cryptography. The chaotic outputs of many space units are used for
encryption simultaneously. This system shows satisfactory cryptographic
properties of high security; fast encryption (decryption) speed; and robustness
against noise disturbances in communication channel. The overall features of
this spatiotemporal-chaos-based cryptosystem are better than chaotic
cryptosystems known so far, and also than currently used conventional
cryptosystems, such as the Advanced Encryption Standard (AES).Comment: 11 pages, 3 figure
Storm-induced changes in pCO2 at the sea surface over the northern South China Sea during Typhoon Wutip
In situ oceanographic measurements were made before and after the passage of Typhoon Wutip in September 2013 over the northern South China Sea. The surface geostrophic circulation over this region inferred from satellite altimetry data features a large‐size anticyclonic eddy, a small‐size cyclonic eddy, and smaller‐size eddies during this period. Significant typhoon‐induced changes occurred in the partial pressure of CO2 at the sea surface (pCO2sea) during Wutip. Before the passage of Wutip, pCO2sea was about 392.92 ± 1.83, 390.31 ± 0.50, and 393.04 ± 4.31 μatm over the cyclonic eddy water, the anticyclonic eddy water, and areas outside two eddies, respectively. The entire study region showed a carbon source (1.31 ± 0.46 mmol CO2 m?2 d?1) before Wutip. In the cyclonic eddy water after Wutip, high sea surface salinity (SSS), low sea surface temperature (SST), and high pCO2sea (413.05 ± 7.56 μatm) made this area to be a carbon source (3.30 ± 0.75 mmol CO2 m?2 d?1). In the anticyclonic eddy water after Wutip, both the SSS and SST were lower, pCO2sea was also lower (383.03 ± 3.72 μatm), and this area became a carbon sink (-0.11 ± 0.55 mmol CO2 m?2 d?1), in comparison with the pretyphoon conditions. The typhoon‐induced air‐sea CO2 flux reached about 0.03 mmol CO2 m?2 d?1. Noticeable spatial variations in pCO2sea were affected mainly by the typhoon‐induced mixing/upwelling and vertical stratifications. This study suggests that the local air‐sea CO2 flux in the study region was affected significantly by oceanographic conditions during the typhoon
The role of drop shape in impact and splash
The impact and splash of liquid drops on solid substrates are ubiquitous in
many important fields. However, previous studies have mainly focused on
spherical drops while the non-spherical situations, such as raindrops, charged
drops, oscillating drops, and drops affected by electromagnetic field, remain
largely unexplored. Using ferrofluid, we realize various drop shapes and
illustrate the fundamental role of shape in impact and splash. Experiments show
that different drop shapes produce large variations in spreading dynamics,
splash onset, and splash amount. However, underlying all these variations we
discover universal mechanisms across various drop shapes: the impact dynamics
is governed by the superellipse model, the splash onset is triggered by the
Kelvin-Helmholtz instability, and the amount of splash is determined by the
energy dissipation before liquid taking off. Our study generalizes the drop
impact research beyond the spherical geometry, and reveals the potential of
using drop shape to control impact and splash.Comment: 14 pages, 4 figure
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