高速数字设计中的反射分析

随着集成电路开关速度的提高以及PCB（Printed Circuit Board）板密度的增加,信号完整性问题已成为高速PCB设计必须关注的问题之一,对信号进行完整性分析已经成为高速数字电路设计中的一个必要环节。本文介绍了高速PCB设计中出现的信号完整性问题,对相关的时序、反射、串扰和地弹等问题进行了深入讨论,并利用Hyperlynx对其作了相应的仿真。根据以上研究的结果,比较了不同的端接策略,验证了解决方案的有效性,也进一步表明信号完整性分析对于高速PCB设计的重要性。     

基于最小熵的完整性度量

在实际计算机系统中可信信息不可避免地会被更改,因此有必要定量刻画信息的完整性,目的在于度量有多少的更改是可容忍的.本文针对攻击者能够一次最大可能更改可信信息的情况,结合信息流完整性模型,将程序建模为信道,使用最小熵定量描述信息完整性.首先刻画信息完整性中的污染和抑制两种情形.基于此,进一步给出污染和信道容量之间的关系;并讨论复合程序的完整性的问题.最后,分析讨论负信息流的情况.     

TMWSNs中一种确保数据完整性的高能效时空Top-k查询协议

时空Top-k查询是TMWSNs（双层移动无线传感网）中的一类重要查询.在敌对环境中,攻击者易通过捕获TMWSNs中的关键节点来破坏时空Top-k查询的数据完整性.提出一种确保数据完整性的时空Top-k查询处理协议VIP-TQ.该协议利用虚拟化节点技术与绑定加密技术通过构建传感器节点的数据预处理方法、数据存储节点的时空Top-k查询处理方法以及Sink端的数据完整性验证方法来实现TMWSNs中时空Top-k查询的数据完整性保护.理论分析和实验结果显示,VIP-TQ能够以100%的概率侦测出不完整的时空Top-k查询结果,并具有相对已有方案更高的能效性.     

使用防护布线减小差分传输线间的高频串扰噪声

随着高速电路的不断发展,差分传输线得到了越来越广泛的应用。它具有低辐射和较好的抗共模噪声能力。但是传统的差分线结构不能有效的降低邻近差分对之间的串扰噪声,这将影响到高速系统的信号完整性。文章针对使用防护布线的方法,讨论了三种不同结构的防护布线,在全波电磁仿真软件HFSS中建立了三维物理模型,利用混模S参数分析了它们对于减小串扰噪声的作用,从场的角度对比了它们的电磁屏蔽效果,并对如何使用防护布线提出了一些建议。     

Lightweight integrity verification scheme for cloud based group data

In order to protect the security of the data stored in the cloud by group users,a data integrity verification scheme was designed which can protect the privacy of the group users.The scheme can efficiently detect the shared data in the cloud and support the dynamic updating of the data,and use the characteristic of the ring signature to hide the iden-tity of the signer corresponding to the data block.That is,the third-party verifier can not spy on the users identity and other private information when validating.The aggregated approach is used to generate data labels,which reduces the storage cost of labels and supports the dynamic operation of group data,so that the users in the group can easily modify the cloud group data.     

页岩气水平井固井水泥环状态对套管力学完整性的影响

大位移页岩气井的井眼轨迹复杂,且压裂开发过程中经常出现由于水泥环缺陷引发的套变损伤问题。针对页岩气井压裂过程中高泵压大排量的特点,采用有限元分析方法,通过优化模型网格划分,建立了适用于页岩气井复杂井眼轨迹下套管力学完整性计算的套管-水泥环-地层组合体模型,讨论了水泥环缺失角度、缺失厚度、缺失长度及复合缺陷对造斜段及水平段局部屈曲部分套管力学完整性的影响。结果表明,套管的周向应力随水泥环弹性模量的增大而减小,受泊松比影响较小。水泥环角度缺失会使套管出现应力集中现象,当缺失角度超过90°,应力集中现象得到减缓。随着水泥环缺失厚度的增加,套管所受应力增大。无论是造斜段还是水平段,不同缺失角度下,水泥环厚度、套管尺寸及泵压对套管应力的影响类似,趋势均为随着缺失角度的增加,套管应力先增大后减小。水泥环缺失的临界部位会产生应力突变,该位置也是最容易发生套损的部位。同一缺失厚度下,套管应力最大值随着缺失角度的增加而先增加后减小;同一缺失角度下,套管应力最大值随着缺失厚度的增加而增加。随着缺失角度的增加,水泥环缺失部位对应套管沿管长方向的等效应力先增加后减小。水泥环越厚,套管等效应力越小。在相同厚度下,水泥环剩余厚度越薄,套管等效应力越大,全部缺失时应力水平最大。     

“工程岩体分级”国家标准在高坝洲工程的应用

采用国家标准《工程岩体分级标准》（送审稿１９９１年）,对高坝洲坝基岩体划分的各基本地质单元,抓住其岩石坚硬程度和岩体完整程度这两大复合分级因素,平行地进行定性分级。在着重考虑其质量和稳定性的基础上,给出了各级岩体的物理力学参数范围值,这些参数值含有岩体综合物理力学特征,这更有利于从整体上反映工程岩体的质量和稳定性能。     

Structural integrity and damage type in military aircraft

This paper discusses the nature of the damage which can cause unanticipated, early fleet failures in legacy military aircraft. This damage often takes a form quite unlike the notional cracking which is used in structural integrity design, but can lead to high costs, or reduced fleet availability, by requiring additional costly inspections and recovery programs in response to discovery of the damage. Using examples from Australian fleets the paper demonstrates that a lack of diagnostic and prognostic tools contributed to the impact of the damage on the fleet. Development of even simple prognostic and diagnostic tools could reduce the fleet impact and cost of discovered damage, and would ultimately allow the non‐crack damage to be incorporated into design to achieve a much more global level of damage tolerance. The paper discusses the key differences between these non‐crack damage forms and the more traditional crack‐like defect which is used in current damage tolerance based structural integrity management approaches for these aircraft. These differences are associated principally with damage variability and damage location, and they challenge some aspects of our existing structural integrity design methods such as reliance on testing and analysis of supposedly ‘representative’ example of aircraft structure. The larger challenge is to fully exploit the principles of damage tolerant structural design and management, and the paper argues that to achieve this we need to maintain a move towards a broader, risk‐based approach to structural integrity management. This longer‐term goal will also involve a reappraisal of the nature and distribution of damage, and a fundamental shift in our crack‐centric view of structural integrity, additional diagnostic and prognostic tools for such damage would be essential for developing this transition to a more global risk‐based damage management approach.     

早餐食品安全的社会性规制问题——基于网络曝光的33个事件分析

早餐对于国民健康有至关重要的意义,随着早餐种类愈加丰富,消费者如何选购健康、安全的早餐愈加困难。基于扎根理论,分析早餐市场混乱的深层原因,并探索通过食育来培养消费者食品安全意识的途径,以减少食品安全事件的发生。运用NVivo11软件对33个食品事件进行归纳分析,研究结果表明早餐市场混乱的浅层原因为食品安全法律体系不完善,深层原因为消费者食品安全意识薄弱,可通过社会规制从根本规范早餐市场:鼓励经营者诚信经营,进而合法经营;通过食育中的饮食教育提升国民食品安全意识,促进食品市场的有序性。     

Antibacterial mode of action of seed essential oil of Eleutherococcus senticosus against foodborne pathogens

This study investigated the antibacterial mechanism of action of the seed essential oil of Eleutherococcus senticosus (ESEO) against foodborne pathogenic bacteria. Preliminarily, the ESEO (1000 μg disc^?1) showed potential antibacterial effect as diameter of inhibition zones (12.0 ± 0.2–37.0 ± 2.0 mm) against the tested foodborne pathogens. The MIC and MBC values of ESEO against the tested bacteria were found in the range of 125–500 and 500–1000 μg mL^?1, respectively. At MIC concentration, the ESEO had potential inhibitory effect on the cell viability of the tested pathogens. In addition, SEM analysis showed the inhibitory effect of ESEO as confirmed by considerable morphological alterations on the cell wall of B. cereus ATCC 13061 and E. coli O157:H7 ATCC 43889. Moreover, the ESEO revealed its mode of action against foodborne pathogens on membrane integrity as confirmed by release of extracellular ATP, 260‐nm absorbing materials and leakage of potassium ions. These findings confirm that the ESEO can be used as a potential antibacterial agent in food industry to inhibit the growth of various foodborne pathogens.