A blind dual color images watermarking based on quaternion singular value decomposition

Multimedia Tools and Applications - With the rapid development of the Internet, the color digital image copyright protection is facing severe challenges. Simultaneously, the color digital images...     

努力攀登科技高峰 为把石化工业建成支柱产业多做贡献

概述中国石化总公司成立以来所取得的重大科技成果。     

高级加密标准Rijndael圈密钥生成算法的C语言实现

在Rijndael加密算法中,每个明文块都要经过Nr+1圈的加密,而每一圈都要进行密钥加密处理。该文探讨了如何由给定的密钥种子(主密钥)生成各圈子密钥的方法,并给出了实现密钥扩展的主要C语言代码。     

An improved color image watermarking scheme based on Schur decomposition

Multimedia Tools and Applications - With the rapid development of computer technology, the copyright protection of color image is becoming a more and more urgent problem. In this paper, an improved...     

氧化铁纳米棒的制备及其在光催化降解水溶性活性染料中的应用

采用均相沉淀法制备了半导体纳米材料α-Fe2O3.通过XRD、TEM等手段对该材料进行了分析.研究了烧结温度、光催化剂的用量、光照等因素对催化剂光催化降解活性染料的影响.并用红外和紫外的分析方法验证了光催化降解效果.结果表明,在适当的用量和350℃烧结并在紫外光照射下,α-Fe2O3对活性染料B-RN蓝、活性艳兰K-NR有极强的光催化降解活性.     

空调冷水一次泵变流量系统设计探讨

介绍了空调冷水一次泵变流量系统的工作原理、组成、优点及适用性。阐述了冷水机组的选择、冷水机组的启停控制、冷水泵的选择及控制、旁通管及旁通控制阀的配置、压差及流量传感器的选择等5个方面的设计要点。     

锑对FCC催化剂上镍的脱氢活性钝化机理的研究

利用红外光谱法、差热分析等测试手段,对石油催化裂解中的共Y—15FCC催化剂在镍沉积前后,及再经Sb钝化剂处理后的催化剂分别进行了分析考察.由红外光谱对催化剂骨架测定,及用吡啶作探针的酸中心测定,发现镍、锑基本上不破坏催化剂的骨架及酸中心.由DTA图可看到,空白催化剂在200℃～1200℃无任何吸热或放热峰出现.但当镍沉积后,在810℃附近有一放热峰,说明在高温下镍与分子筛有较强的相互作用,估计有NiAl_2O_4生成.当催化剂上有镍及锑沈积后,在530℃、600℃、680℃等处有吸热峰,说明有共熔物及NiSb_2,Ni_4Sb合金生成,这可能是锑钝化剂对镍脱氢产生钝化作用的原因.     

莱钢余热资源利用现状及其设想

在总结莱钢几年余热利用情况及存在的问题的基础上,阐明了如何进一步利用余热资源的设想。     

Orthogonal and Biorthogonal $sqrt 3$-Refinement Wavelets for Hexagonal Data Processing

The hexagonal lattice was proposed as an alternative method for image sampling. The hexagonal sampling has certain advantages over the conventionally used square sampling. Hence, the hexagonal lattice has been used in many areas. A hexagonal lattice allows radic3, dyadic and radic7 refinements, which makes it possible to use the multiresolution (multiscale) analysis method to process hexagonally sampled data. The radic3-refinement is the most appealing refinement for multiresolution data processing due to the fact that it has the slowest progression through scale, and hence, it provides more resolution levels from which one can choose. This fact is the main motivation for the study of radic3-refinement surface subdivision, and it is also the main reason for the recommendation to use the radic3-refinement for discrete global grid systems. However, there is little work on compactly supported radic3 -refinement wavelets. In this paper, we study the construction of compactly supported orthogonal and biorthogonal radic3-refinement wavelets. In particular, we present a block structure of orthogonal FIR filter banks with twofold symmetry and construct the associated orthogonal radic3-refinement wavelets. We study the sixfold axial symmetry of perfect reconstruction (biorthogonal) FIR filter banks. In addition, we obtain a block structure of sixfold symmetric radic3-refinement filter banks and construct the associated biorthogonal wavelets.