XRD测定炭素材料的石墨化度

介绍了用X射线衍射(XRD)测定炭素材料石墨化度的原理和方法,指出:用高纯硅粉作内标校准测量误差是必要的;当炭石墨的衍射线呈现不对称时,必须进行多重峰分离,这说明试样含有不同石墨化度的组分,同时可计算出它们相应的含量。     

基于内容的图像检索系统

文章介绍了基于内容的图像检索技术及其优势，并举了几个例子。     

Known-key distinguishers on type-1 Feistel scheme and near-collision attacks on its hashing modes

We present some known-key distinguishers for a type-1 Feistel scheme with a permutation as the round function. To be more specific, the 29-round known-key truncated differential distinguishers are given for the 256-bit type-1 Feistel scheme with an SP (substitution-permutation) round function by using the rebound attack, where the S -boxes have perfect differential and linear properties and the linear diffusion layer has a maximum branch number. For two 128-bit versions, the distinguishers can be applied on 25-round structures. Based on these distinguishers, we construct near-collision attacks on these schemes with MMO (Matyas-Meyer-Oseas) and MP (Miyaguchi-Preneel) hashing modes, and propose the 26-round and 22-round near-collision attacks for two 256-bit schemes and two 128-bit schemes, respectively. We apply the near-collision attack on MAME and obtain a 26-round near-collision attack. Using the algebraic degree and some integral properties, we prove the correctness of the 31-round known-key integral distinguisher proposed by Sasaki et al. We show that if the round function is a permutation, the integral distinguisher is suitable for a type-1 Feistel scheme of any size.     

超静定结构综合预应力度直接设计方法的研究

提出综合预应力度的概念,并以此提出综合预应力度直接算法的计算原理,从而克服利用传统预应力度设计计算超静定结构时所面临的重复计算问题,为预应力结构的计算提供一个快捷方法。     

消弧线圈接地系统接地故障波形分析及调谐参数计算

通过对66kV系统发生单相接地故障时的暂态过程波形分析,计算出运行中消弧线圈的脱谐度和接地电容电流等参数,从而分析消弧线圈的补偿情况和灭弧效果。并对实际发生的弧光接地过电压进行了分析。     

Multimode polarization degree of mixture optical states in integrated directional couplers

Mixture multimode optical field classical states propagating in N?×?N integrated directional couplers are analyzed by using the density matrix formalism in a N-dimensional optical space. These mutimode optical fields present a kind of generalized polarization and accordingly a definition of a multimode polarization degree is proposed. It is based on the distance measure between a mixture state and an unpolarized state in a N-dimensional optical space so that in the case N=2 the standard polarization degree is recovered. It is shown that directional couplers can reduce or increase remarkably the multimode polarization degree of a mixture state. Likewise a simple measurement technique, based on Y junctions, of this multimode polarization degree is proposed. Finally all the results can be formally extended to the special case of multimode single photon quantum states.     

自动门微波传感器原理

自动门微波传感器是采用多普勒原理的一种自动门微波传感器。自动门微波传感器是利用微波的传输性能好、易反射、被吸收功率易测量等特点,用专门的微波振荡器来产生微波,特定的天线收发微波。     

石上井田B4煤层构造形态和厚度的趋势面分析

利用石上井田内施工的43个钻孔资料,对其B4煤层底板标高和煤层厚度进行了趋势面分析,得出石上井田B4煤层为一向斜构造,向斜轴走向NE,煤层厚度往轴部变厚,而两翼较薄。     

基于能源安全考量中国经济发展与石油依赖

随着经济发展,中国经济对石油进口的依赖度不断攀升,石油问题已经影响到了中国经济和能源安全。通过研究发现,中国经济发展与石油消费、石油进口和石油依存度存在长期稳定的均衡关系,并且发现经济发展与石油消费和石油进口不仅存在双向的因果关系,而且存在经济发展到石油依存度单向因果关系。最后,提出有关石油安全的一些建议。     

皂角种子胶羧甲基化反应的研究与应用

研究了皂角种子胶与氯乙酸的羧甲基化反应,主要讨论了原料用量,原料颗粒大小及反应温度等因素对羧甲基化反应取代度的影响。