A Practical Regular LDPC Coded Scheme for Physical-Layer Information Security

In this paper,we aim to design a practical low complexity low-density parity-check(LDPC)coded scheme to build a secure open channel and protect information from eavesdropping.To this end,we first propose a punctured LDPC coded scheme,where the information bits in a codeword are punctured and only the parity check bits are transmitted to the receiver.We further propose a notion of check node type distribution and derive multi-edge type extrinsic information transfer functions to estimate the security performance,instead of the well-known weak metric bit error rate.We optimize the check node type distribution in terms of the signal-to-noise ratio(SNR)gap and modify the progressive edge growth algorithm to design finite-length codes.Numerical results show that our proposed scheme can achieve a lower computational complexity and a smaller security gap,compared to the existing scrambling and puncturing schemes.

CWRF-based ensemble simulation of tropical cyclone activity near China and its sensitivity to the model physical parameterization schemes

To evaluate the downscaling ability with respect to tropical cyclones(TCs)near China and its sensitivity to the model physics representation,the authors performed a multi-physics ensemble simulation with the regional Climate-Weather Research and Forecasting(CWRF)model at a 30 km resolution driven by ERA-Interim reanalysis data.The ensemble consisted of 28 integrations during 1979-2016 with varying CWRF physics configurations.Both CWRF and ERA-Interim can generally capture the seasonal cycle and interannual variation of the TC number near China,but evidently underestimate them.The CWRF downscaling and its multi-physics ensemble can notably reduce the underestimation and significantly improve the simulation of the TC occurrences.The skill enhancement is especially large in terms of the interannual variation,which is most sensitive to the cumulus scheme,followed by the boundary layer,surface and radiation schemes,but weakly sensitive to the cloud and microphysics schemes.Generally,the Noah surface scheme,CAML(CAM radiation scheme as implemented by Liang together with the diagnostic cloud cover scheme of Xu and Randall(1996))radiation scheme,prognostic cloud scheme,and Thompson microphysics scheme stand out for their better performance in simulating the interannual variation of TC number.However,the Emanuel cumulus and MYNN boundary layer schemes produce severe interannual biases.Our study provides a valuable reference for CWRF application to improve the understanding and prediction of TC activity.

Mesoscale Numerical Simulation Study of Warm Fog Dissipation by Salt Particles Seeding

Based on the dynamic framework of WRF and Morrison 2-moment explicit cloud scheme, a salt-seeding scheme was developed and used to simulate the dissipation of a warm fog event during 6–7 November 2009 in the Beijing and Tianjin area. The seeding effect and its physical mechanism were studied. The results indicate that when seeding fog with salt particles sized 80 μm and at a quantity of 6 gm^（-2） at the fog top, the seeding effect near the ground surface layer is negative in the beginning period, and then a positive seeding effect begins to appear at 18 min, with the best effect appearing at 21 min after seeding operation. The positive effect can last about 35 min. The microphysical mechanism of the warm fog dissipation is because of the evaporation due to the water vapor condensation on the salt particles and coalescence with salt particles.The process of fog water coalescence with salt particles contributed mostly to this warm fog dissipation. Furthermore, two series of sensitivity experiments were performed to study the seeding effect under different seeding amounts and salt particles sizes. The results show that seeding fog with salt particles sized of 80 μm can have the best seeding effect, and the seeding effect is negative when the salt particle size is less than 10 μm. For salt particles sized 80 μm, the best seeding effect, with corresponding visibility of 380 m, can be achieved when the seeding amount is 30 g m^（-2）.

Novel scheme of manipulating topological physics by using a single degenerate cavity

Subject Code:F05 With the support by the National Natural Science Foundation of China,the research group from the Key Lab of Quantum Information(CAS)led by Prof.Guo Guangcan(郭光灿)at the University of Science and Technology of China proposed a new routine to manipulate topological physics using only a single