An Explanation for the Undetection of Radio Pulsar in Supernova 1987A

Supernova 1987 A is a core collapse supernova in the Large Magellanic Cloud, inside which the product is most likely a neutron star. Despite the most sensitive available detection instruments from radio to γ-ray wavebands being exploited in the pass thirty years, there have not yet been any pulse signals detected. By considering the density of the medium plasma in the remnant of 1987 A, we find that the plasma cut-off frequency is approximately7 GHz, a value higher than the conventional observational waveband of radio pulsars. As derived, with the expansion of the supernova remnant, the radio signal will be detected in 2073 A.D. at 3 GHz.

ERROR-DETECTING CODES AND UNDETECTED ERROR PROBABILITIES

The definition of good codes for error-detection is given. It is proved that a (n, k) linear block code in GF(q) are the good code for error-detection, if and only if its dual code is also. A series of new results about the good codes for error-detection are derived. New lower bounds for undetected error probabilities are obtained, which are relative to n and k only, and not the weight structure of the codes.

Simple Three-Party Password Authenticated Key Exchange Protocol

Three-party password authenticated key exchange (3PAKE) protocol plays a significant role in the history of secure communication area in which two clients agree a robust session key in an authentic manner based on passwords. In recent years, researchers focused on developing simple 3PAKE (S-3PAKE) protocol to gain system e?ciency while preserving security robustness for the system. In this study, we first demonstrate how an undetectable on-line dictionary attack can be successfully applied over three existing S-3PAKE schemes. An error correction code (ECC) based S-3PAKE protocol is then introduced to eliminate the identified authentication weakness.

SABATPG-A Structural Analysis Based Automatic Test Generation System

A TPG system, SABATPG, is given based on a generic structural model of large circuits. Three techniques of partial implication, aftereffect of identified undetectable faults and shared sensitization with new concepts of localization and aftereffect are employed in the system to improve FAN algorithm. Experiments for the 10 ISCAS benchmark circuits show that the computing time of SABATPG for test generation is 19.42% less than that of FAN algorithm.

The undetected error probabilities of combinatorial codes and their dual codes

IT is known that the average undetected error probability （UEP） of a binary [n, k] code Con a binary symmetric channel with crossover probability p is given byPe（p） = sum from i=1 Aipi（1-p）n-1, （1）where （A0, A1,…, An） is the weight distribution of C. If for all 0≤p≤0.5, Pe（p）≤Pe（0. 5） = 2k-n-2-n, then C is called good for error detection. Moreover, if Pe （p） ismonotonously increasing in the interval [0, 0.5], then C is called proper. Clearly, propercodes are good.

A Method to Estimate the Steganographic Capacity in DCT Domain Based on MCUU Model

In order to estimate maximum steganographic capacity of discrete cosine transform（DCT） domain in JPEG image, this paper presents a method based on the maximize capacity under undetectable model（MCUU）. We analyze the relation between steganographic capacity and affecting factors（image size, steganography operator, loading band, embedding intensity and image complexity）. Then we design a steganography analyzer architecture and a steganographic algorithm which can dynamically increase the steganographic capacity. Compared with other methods of embedding capacity estimation in DCT domain, the proposed methods utilizes general steganalysis methods rather than one specific steganalysis technique and takes five essential factors into account, which improves the commonality and comprehensiveness of capacity estimation, respectively. The experimental results show that steganographic capacity for quantization index modulation（QIM） is almost twice that of spread spectrum（SS） based on MCUU model.

ERROR DETECTION CAPABILITY OF SHORTENED HAMMING CODES AND THEIR DUAL CODES

The undetected error probability and error detection capability of shortened Hamming codes and their dual codes are studied in this paper. We also obtain some interesting properties for the shortened Simplex codes.