BIOCIDAL ACTIVITY OF A PEROXIDASE-CATALYZED SANITIZER AGAINST SELECTED BACTERIA ON INERT CARRIERS AND EGG SHELLS

Microbial contamination of table eggs has become an important public health problem. In this study, peroxidase-catalyzed compound (PCC), which is innocuous to humans, was tested for its bactericidal activity on a variety of bacteria on inert carriers and on egg shell surfaces. When inert carriers containing Salmonella choleraesuis, Staphylococcus aureus and Pseudomonas aeruginosa were exposed to PCC, population reductions were within acceptable performance standards for standard and simulated hard water conditions. When evaluated for sporicidal activity, PCC gave no positive carriers in a total of 60 carriers tested for either Bacillus subtilis or Clostridium sporogenes. Enterococcus faecalis and Pseudomonas fluorescens viable cells on egg shell surfaces were determined after dip treatment with deionized distilled water, PCC or chlorine-treated (200 ppm) water for 1, 3 and 5 min and compared with those of a control without dip treatment. All treatments significantly reduced the viable cells (log₁₀ CFU/egg) compared to controls for both strains (p < 0.05). Populations of both strains surviving chlorine and PCC were significantly lower than surviving deionized-distilled water, although PCC gave higher recoveries than chlorine (p < 0.05). Populations exposed to PCC treatment were significantly decreased after 3 and 5 min, respectively (p < 0.05). The results of this study indicate that PCC has potential as a table egg sanitizer that could replace the other egg sanitizers which may be environmentally problematic. Based on the inert carrier studies, PCC may also be an effective disinfectant for egg processing equipment and plastic egg cartons in the presence of hard water or contaminating soil .     

Distributed Spectrum Sharing Scheme for Multiuser Orthogonal Frequency-Division Multiplexing Cognitive Radio Networks

This paper presents a novel spec- trum sharing design aiming at optimising the performance of a Multiuser Orthogonal Freq- uency-Division Multiplexing （MU-OFDM） Co- gnitive Radio Network （CRN） that consists of multiple secondary Transmitter-Receiver （Tx-Rx） pairs. For most MU-OFDM systems, the Exc- lusive Subchannel Assignment （ESA） is an efficient resource allocation method. Noneth- eless, it is inappropriate for the network consi- dered in this paper, because subchannels shar- ing among secondary Tx-Rx pairs can further improve the system performance. We investi- gate the Weighted Sum Rate （WSR） maximi- zation problem under the Shared Subchannel Assignment （SSA）, where each subchannel is shared by multiple secondary Tx-Rx pairs. With Lagrangian duality technique, we decompose the original resource allocation problem into sev- eral sub-problems on each subchannel and pro- pose a duality-based suhchannel sharing ap- proach. For practical realisation in the cogni- tive systems without central control entity, a distributed duality-based WSR maximization scheme is presented. Simulation results mani- fest that the proposed scheme achieves sig- nificantly better performance than ESA duality scheme.     

双语教学的深入思考

结合数字信号处理课程双语教学的实践及所了解的英国专业课程的教学情况,阐述了在实施双语教学中应当注意的问题,包括双语教学的循序渐进,突出原版教材的特色,并提出双语教学应坚持学生自愿的原则,主张小班上课,教学过程中任课教师编写教案手稿发给学生;在教学方法上尝试自主性教与学。     

MIMO系统自适应均衡技术进展与展望

随着3G，B3G／4G通信技术的发展，均衡技术在MIMO通信系统的应用越来越受到关注。本文分类总结了MIMO系统均衡的LMS，RLS，CMA等常用及其改进算法，介绍了线性、格型、判决反馈（DFE）、Turbo等类型均衡器。研究了国内外MIMO均衡领域的发展现状，指出了其困难所在，并对未来的研究重点及其方向进行了展望。     

Al-Cr二元合金中的一个新正交相O-Al_(11)Cr_2

通过透射电镜原位观察,发现单斜η-Al11Cr2相在800℃保温2h后,其三个主带轴电子衍射图中的超点阵弱点逐渐减弱直至消失,且a轴和c轴所成的角度由91&#176;变为90&#176;,这些变化意味着单斜η-Al11Cr2相在加热后转变为一个新相,点阵参数为a=1.2428nm,b≈1.2658nm,c≈3．0456nm的体心正交相,命名为O-Al11Cr2.其[010]电子衍射图具有伪十次对称特点,因此也是一个十重对称准晶近似相.     

改进的BP网络在调制识别中的应用

研究了BP网络初始权值的选择和网络结构的优化方法，在显著减小网络拓扑结构的基础上，提高了网络的泛化能力和识别性能。引入分段传递函数，并根据网络性能调节传递函数，改善了网络的训练速度。改进后的BP网络应用于通信信号调制识别。仿真结果验证了算法的有效性和鲁棒性。     

多载波码分多址系统的多用户检测

正交多载波码分多址（MC—CDMA）是近年来无线通信研究的热点。本文介绍了MC—CDMA系统的多用户检测技术。分析了与直接序列（DS—CDMA）系统的对偶性关系，并通过将两种系统的多用户检测算法分类比较，指出将DS—CDMA的多用户检测算法引入到MC—CDMA中的可行性，讨论了MC—CDMA多用户检测的发展方向。     

无反馈分布式视频编码中的速率控制算法

针对现有比特平面级编码端速率控制算法估计精度要求高的问题,提出了一种帧级编码端速率控制算法。该算法通过在编码端利用分层快速运动补偿内插产生高质量的边信息估计,并根据循环移位去除比特平面间的级别性,使每个比特平面的编码速率均匀化,从而实现帧级别的速率控制。实验结果表明,与现有算法相比,所提算法对中高速运动视频边信息估计质量有明显提升,且解码视频的平均PSNR(peak signal-to-noise ratio)均有提高。     

Quantitative analysis of SiC polytype distributions by the Rietveld method

The quantitative determination of SiC polytype distributions is very difficult using traditional X-ray powder diffraction quantitative analysis methods, because the diffraction patterns of the various polytypes partially superimpose. The whole pattern fitting technique encapsulated in the Rietveld method is introduced to solve this problem. The detection limits for each polytype can be estimated based on their standard deviations. The results of both synthesized and experimental diffraction data show that the Rietveld method can give precise and accurate percentage compositions of the four most common SiC polytypes. This approach provides a practical tool to relate the preparation conditions to performance properties of SiC-based materials. This revised version was published online in November 2006 with corrections to the Cover Date.