2008国际信息安全标准化趋势——ISO／IEC JTC1／SC27第36届工作组会议热点追踪

介绍了2008年ISO/IEC JTC1/SC27第36届各工作组会议热点,分析了国际信息安全标准化发展趋势,特别是特定领域信息安全管理、低功耗加密、脆弱性披露责任、信息安全事件管理、身份管理和隐私保护等.结合我国参与SC27的实践,提出后续工作建议.     

Effects of supercritical carbon dioxide on volatile formation from Maillard reaction between ribose and cysteine

BACKGROUND: Supercritical carbon dioxide (SC‐CO₂) technology is being used in an increasing number of food‐manufacturing applications; however, its effect on the Maillard reaction is not well studied. The objective of this study was to investigate the effect of SC‐CO₂ treatment (140 °C, 40 MPa) on the Maillard reaction of an aqueous ribose–cysteine model system under varying pH conditions (5.6, 7.0 and 8.0), with emphasis on the formation of volatile compounds. RESULTS: SC‐CO₂ had a suppressing effect on the browning stages of the reaction under acidic and neutral pH conditions, while it appeared to have an accelerating effect at pH 8.0. Over 70 volatile compounds were positively identified from the headspace of the model system by gas chromatography–mass spectrometry. The volatiles were dominated by sulfur‐containing compounds including thiophenes and fused bicyclic sulfur‐containing compounds under all experimental conditions. Several compounds, including 2‐methyl‐3‐furanthiol, 2‐furanmethanethiol, 3‐thiophenethiol, and 2‐methyl‐3‐thiophenethiol, and one of the intermediates, furfural, were generated in much higher amounts in the SC‐CO₂‐treated samples, especially at alkaline and neutral pH values. CONCLUSION: SC‐CO₂ treatment was inhibitory to the formation of most volatiles in the Maillard reaction, but enhanced the formation of some intermediates and well‐known meaty flavoured compounds. Copyright © 2007 Society of Chemical Industry     

基于电力线信道的OFDM同步算法的仿真

针对OFDM在电力线载波通信中的应用,分析研究了SC的OFDM同步算法,并在此基础上提出了一种针对电力线信道的改进的OFDM同步方案。该方案在保证有效符号定位的情况下,扩大了频率偏移的估计范围,改善了归一化频偏在边界点附近的估计失真问题。通过所建立的电力线信道模型和电力线载波通信仿真平台,文章对提出的同步算法进行了仿真,证明了该方案的可行性。     

Chromosome instability and unusual features of some widely used strains of Candida albicans

Electrophoretic karyotyping of the Candida albicans revealed a different migration pattern of ChR in three different stocks of the sequencing strain SC5314. In one stock, the high instability of ChR size prevented the migration of ChR as a compact band; ChR appeared, instead, as a smear. In some stocks, ChR and/or Ch1 ploidy diminished, suggesting mixed populations of disomic and monosomic cells. Similarly, some stocks of widely used derivatives CAI4 and BWP17 contained smearing of ChR. In addition, the most manipulated strain in the lineage of SC5314, the last derivative, BWP17, acquired an increase in the size of Ch7b and revealed an unusual property. BWP17 did not tolerate a well-established procedure of telomere-mediated fragmentation of a chromosome; the remaining intact homologue always duplicated. We suggest that some stocks of SC5314 are unstable and that BWP17 may not be appropriate for general studies. Instead of BWP17 or CAI4, we recommend using for general research CAF4-2, which is a relatively stable Ura- derivative, and which has been successfully used for more than a decade in our laboratory.     

机房集中监控系统维护方法探讨

对机房集中监控系统三级监控单元SU、SC、SS所使用的各种物理设备的类型及其原理进行分析，提出有针对性的物理设备故障检测技术及日常维护方法。所探讨的这些故障检测技术及维护方法，均经过实践证明具有高准确度，可以为机房维护人员准确分析设备故障状态提供参考，及时有效地采取措施，提高工作效率和降低维护费用。     

A simple and effective design strategy to increase power conversion efficiency of linear charge pumps

This paper introduces a simple design strategy to increase the power efficiency of linear charge pumps. The technique exploits a voltage amplitude of the clock signal lower than the supply voltage to reduce the power conversion losses. The nominal output voltage is maintained unaltered by increasing the number of stages.     

Power and energy management of grid/PEMFC/battery/supercapacitor hybrid power sources for UPS applications

This paper presents a hybrid power and energy source supplied by a proton exchange membrane fuel cell (PEMFC) as the main power source in an uninterruptible power supply (UPS) system. To prevent the PEMFC from fuel starvation and degradation and realize their seamless linking in the hybrid UPS system, the power and energy are balanced by the battery and/or supercapacitor (SC) as two alternative auxiliary power sources. Based on the modeling and sizing of hybrid power and energy components, the power and energy management strategies and efficiency measurements of four operating modes in UPS system are proposed. To evaluate the proposed strategies, an experimental setup is implemented by a data acquisition system, a PEMFC generating system, and a UPS system including AC/DC rectifier, DC/AC inverter, DC/DC converter, AC/DC recharger and its intelligent control unit. Experimental results with the characteristics of a 300 W self-humidified air-breathing of PEMFC, 3-cell 12 V/5 Ah of batteries, and two 16-cell 120 F/2.7 V of SCs in parallel corroborate the excellent management strategies in the four operating modes of UPS system, which provides the basis for the optimal design of the UPS system with hybrid PEMFC/battery/SC power sources.     

氧化锌晶须填充尼龙1010的接触和摩擦学性能研究

用球-平面接触方式,测定ZnOw填充尼龙复合材料的压痕蠕变、球压痕硬度和摩擦磨损性能.试验结果表明,压痕试验中尼龙复合材料的压痕深度和蠕变柔量随试验时间而增加.尼龙复合材料的抗压痕蠕变性能和球压痕硬度均随ZnOw的含量增加而增强.尼龙复合材料的蠕变模型符合典型三参数线性粘弹性模型,模型中弹簧刚度和阻尼系数均随ZnOw含量的增加而增加.对摩擦因数和蠕变模型中的时间常数,磨损率和硬度分别进行相关分析,得出摩擦因数与时间常数之间为正比二次方程曲线关系、磨损率和硬度之间为反比二次方程曲线关系.     

极化码串行抵消译码算法延迟性的改进

由Arikan提出的极化码,因其简单的编译码结构引起广泛关注。极化码作为一种高性能的信道编码,编码长度超过2^10会产生优异的性能。在串行抵消（successive cancelation,SC）译码算法结构基础上,其译码延迟随码长增加而加剧。通过分析SC译码算法,提出一种基于冻结比特的改善SC译码算法方案,有效地降低了传统SC译码算法的延迟性。算法改进后相比原来可以降低50%的译码延迟,并引入串行抵消单比特翻转译码算法作为译码补偿,进一步提高译码算法的纠错能力。