On the pseudo-freeness and the CDH assumption

The notion of pseudo-free group was first introduced by Hohenberger (Master’s thesis, EECS Dept., MIT, 2003). Rivest (TCC 2004. LNCS 2951, 505–521, 2004) formalized it and showed that several standard cryptographic assumptions hold on pseudo-free groups, such as the RSA assumption, the strong RSA assumption and the discrete logarithm assumption. Rivest (TCC 2004. LNCS 2951, 505–521, 2004) also proposed some variations of pseudo-free group, and those were formalized by Hirano and Tanaka (Research Reports, Series C: Computer Science, C-239, Tokyo Institute of Technology, 2007). In this paper, we study the relationships among such variations of pseudo-free group. We show that the pseudo-freeness implies the weak pseudo-freeness, and that the pseudo-freeness is equivalent to the pseudo-freeness with generalized exponential expressions. We also show that the computational Diffie-Hellman assumption holds on pseudo-free groups in a slightly varied form.     

Permeability of vitamin B-12 in chitosan membranes. Effect of crosslinking and blending with poly(vinyl alcohol) on permeability

The permeability and diffusion of vitamin B-12 in chitosan, crosslinked chitosans, and chitosan/poly(vinyl alcohol) (PVA) blends were studied using “lag time” technique. Apparently the diffusion coefficient, D, for both crosslinked and blended chitosan membranes depends solely upon the equilibrium swelling ratio, Q, of the material in water. The functional dependence of D on Q was obtained from the data. The partition coefficients calculated for vitamin B-12 in all membranes studied were nearly constant (K ≈ 0.4). The results are shown to be consistent with the “pore type” transport mechanism for vitamin B-12 in these chitosan membranes.     

An explicit application of partition of unity approach to XFEM approximation for precise reproduction of a priori knowledge of solution

The application of the XFEM to fracture mechanics is effective, because a crack can be modeled independently from the meshes and a complex remeshing procedure can be avoided. However, the classical XFEM has an essential problem in the approximation of partially enriched elements, that is, blending elements, which causes a lack of accuracy. For the weighted XFEM, although the numerical results show the effective improvements, it was found that the issue of blending elements still remains upon detailed examination. In the present paper, the PU‐XFEM is formulated as an explicit application of the partition of unity (PU) approach to the XFEM, in order to precisely reproduce a priori knowledge of the solution by enrichment. The PU‐XFEM is applied to two‐dimensional linear fracture mechanics, and its effectiveness is verified. It is consequently found out that the PU‐XFEM precisely reproduces a priori knowledge of the solution and is therefore effective to completely solve the problem of the blending elements. Copyright © 2013 John Wiley & Sons, Ltd.     

等离子体散射分析的改进型交替隐式时域方法

提出了一种改进的交替隐式时域有限差分(FDTD)方法,运用该方法分析了等离子体涂覆导体圆柱的散射特性,为等离子体隐身技术的运用提供了一定的理论指导.该方法在整个问题空间采用完整场形式的场量进行迭代计算,并运用中心差分格式离散极化电流密度辅助方程.仿真实验表明,提出的算法具有无条件稳定特性,其计算效率明显优于以往文献提出的交替隐式FDTD方法,在精度和效率上也稍高于普通的显式FDTD方法.     

浅谈入世后我国农产品质量安全和标准体系建设

<正> 随着农业发展进入新的阶段,农产品质量安全已成为制约我国农业和农村经济发展的突出问题。特别是WTO成立以来,伴随着农产品贸易的自由进程,传统的关税壁垒作用在逐步减弱,以控制农产品质量安全为中心的技术性壁垒的作用在逐步加强,围绕农产品质量安全而产生的贸易摩擦乃至争端呈增长趋势。我国加入WTO之后,无论是农产品的国内市场,还是面对国际农产品贸易,都不可避免地要被卷入这场新的国际角逐。     

Lattice diffusion coefficient of oxygen in lithium oxide

Lattice diffusion coefficients of the oxygen ion in antifluorite-cubic Li₂O were determined employing polycrystalline samples, in the temperature range of 920 ~ 1130°C, by means of the gas-solid isotope exchange and solid-phase analysis technique; use was made of the relationship between the particle-size and grain-size dependences of the grain-boundary enhanced diffusion. The results were described by D = 1.52 × 10³ exp$\text{(?83.3 × 10}{}^3\text{/RT)}\text{cm}{}^2\text{s}$ and showed a good agreement with the previously reported results determined by the gas-phase analysis technique. Diffusion characteristics of the constituent ions in the antifluorite-cubic structure were discussed in comparison with those in fluorite-cubic crystals.     

Ti-Co氧化物中间相的形成与组织结构

采用深胶凝胶工艺技术,以ＣｏＣ１２、Ｔｉ（Ｃ４Ｈ６Ｏ）为原料,经混合、水解、缩聚、固化、氧化制备中间相ＣｏＴｉＯ３的超细粉末,并用扫描差热分析（ＤＴＡ）、Ｘ－射线衍射分析（ＸＲＤ）及航向电子分析（ＴＥＭ）等手段分析了ＣｏＴｉＯ３的形成、原子间键合、晶体结构与组织形貌。     

Crosslinking of PVC and NBR blends

The purpose of our work is to control the interfacial bonds between PVC and NBR using the ammonium salts of triazine thiols and dithiodimorpholine (DTDM) and thereby reveal the relation between the interfacial bonds and the final mechanical properties of products. In the experimental work a two-stage process was used. At first, an NBR/PVC blend was mixed with a mono-tetra-n-butylammonium salt of triazine trithiol at a temperature of 100°C on a two-roll mill to give the branching structure of triazine thiols into PVC. In the second stage branched NBR/PVC reacted with DTDM to afford the branched PVC containing trithiomorphonyl groups. In the presence of ZnO at 160°C trithiomorphonyl groups react with NBR to form a crosslinking structure between NBR and PVC. The mechanical properties of cured NBR/PVC blends were markedly improved by the treatment process and after addition of tetramethylthiuram monosulphide also. The mechanical properties were not improved by increasing the concentration of TT-TBA (tetrabutylammonium salt of 1,3,5-triazine-2,4,6-trithiol) over 4.2 phr.     

Effects of stimulus information and number of stimuli on sequential dependencies in absolute identification.

Three absolute identification experiments examined the effects on sequential dependencies of 2 factors: stimulus information and the number of stimuli used. Data were analyzed by multivariate information analysis. In Exp 1 with 5 university studentswith experience in absolute identification experiments, the stimulus modality was pure tone frequency under masking and no-masking conditions and 4, 6 10, and 16 tones were used. In Exp 2 with 5 university students, luminance levels of light circles were used as stimuli and number of luminance levels was 10 or 16. In Exp 3 with 6 university students, the stimuli were pointer positions along a horizontal line and they were presented either within a small or a large range to manipulate the stimulus information available. Results show that the sequential dependencies became larger as the stimulus information was decreased and as the number of stimuli was increased. Results are discussed in the context of models of sequential dependencies. Results of a multiple regression analysis on the data were compared with those of the information analysis. (PsycINFO Database Record (c) 2010 APA, all rights reserved)