Systematic Encoding and Shortening of PAC Codes

Polarization adjusted convolutional (PAC) codes are a class of codes that combine channel polarization with convolutional coding. PAC codes are of interest for their high performance. This paper presents a systematic encoding and shortening method for PAC codes. Systematic encoding is important for lowering the bit-error rate (BER) of PAC codes. Shortening is important for adjusting the block length of PAC codes. It is shown that systematic encoding and shortening of PAC codes can be carried out in a unified framework.     

联合击中击不中变换相关器

将联合击中击 中变换相关器用于二值图像的目标识别。与常用的联合变换相关器相比，联合击中击不中变换相关器对联合变换相关器输入图像和参考图像进行互补编码。编码的目的在于通过联合变换相关器来一步实现形态学中的击中击不中变换。     

短波差分跳频通信系统抗多音干扰的性能分析

针对应用于军事通信的短波差分跳频系统中存存敌意多音干扰的问题，建立了系统的多音干扰模型，采用一种联合一切尔诺大限的方法，从理论上导出了该系统（无编码）在加性高斯白噪声信道和瑞利衰落信道条件下抗多音干扰的比特误码率性能上界；并采用RS信道编码方法，对尢编码系统在瑞利衰落信道下误码率为10^-3时出现的差错平板进行了改善．数值结果表明编码后的系统较无编码系统能获得约7dB的性能增益，有效提高了抗多音干扰的能力．     

制作具有预期位相调制度的卤化银乳胶位相型薄全息光栅的研究

提出了一种制作具有预期位相调制度的卤化银乳胶位型薄全息光栅的方法。它通过分析所拍摄的第一张全息光栅的数据来获得最佳曝光参量，从而使继后的拍摄，在同样的实验条件下能获得所预期的位相调制度。文中给出了这方法的理论分析和某些应用。     

Bernstein polynomials and learning theory

When learning processes depend on samples but not on the order of the information in the sample, then the Bernoulli distribution is relevant and Bernstein polynomials enter into the analysis. We derive estimates of the approximation of the entropy function x log x that are sharper than the bounds from Voronovskaja's theorem. In this way we get the correct asymptotics for the Kullback–Leibler distance for an encoding problem.     

Analysis of edge and corner points using parabolic dictionaries

Last decade saw the creation of a number of directional representation dictionaries that desire to address the weaknesses of the classical wavelet transform that arise due to its limited capacity for the analysis of edge-like features of two-dimensional signals. Salient features of these dictionaries are directional selectivity and anisotropic treatment of the axes, achieved through the parabolic scaling law. In this paper we will examine the adequacy of such dictionaries for the analysis of edge- and corner-like features of 2D regions through a comprehensive framework for directional parabolic dictionaries, called the continuous parabolic molecules. This work builds on a family of earlier studies and aims to give a broader perspective through the level of generality.     

Performance evaluation of the phase encoded optical CDMA system

Recently, there has been increasing interest in field of Optical CDMA due to its potential for offering unmatched features at ultra high data rates in field of local and metro area networks. In this paper, a very simple method of Optical CDMA encoding known as the Temporal Phase Encoding is discussed and the performance of the system with this encoding technique is evaluated on the basis of number of users, length of the spreading code for 4-phase and 8-phases. Simulation results for the system are presented for upto seven users. Bit error rate curves are plotted with data rate of 1 Gbps. This has been found that performance improves if normalized threshold higher than 0.5 is used.