一种可并行的消息认证码

提出并分析了一种确定的、可并行的消息认证码--DPMAC(deterministic parallelizable message authentication code).它基于分组长度为128-bit的分组密码来构造.使用一个密钥,可以处理任意长度的消息.在底层分组密码是伪随机置换的假设下,使用Game-Playing技术量化了攻击者成功伪造的概率,从而证明了其安全性.

Replacement of methane from quartz sand-bearing hydrate with carbon dioxide-in-water emulsion

The replacement of CH4 from its hydrate in quartz sand with 90:10, 70:30, and 50:50 (W-CO2:W-H2O) carbon dioxide-in-water (C/W) emulsions and liquid CO2 has been performed in a cell with size of empty set 36 x 200 mm. The above emulsions were formed in a new emulsifier, in which the temperature and pressure were 285.2 K and 30 MPa, respectively, and the emulsions were stable for 7-12 h. The results of replacing showed that 13.1-27.1%, 14.1-25.5%, and 14.6-24.3% of CH4 had been displaced from its hydrate with the above emulsions after 24-96 It of replacement, corresponding to about 1.5 times the CH4 replaced with high-pressure liquid CO2. The results also showed that the replacement rate of CH4 with the above emulsions and liquid CO2 decreased from 0.543, 0.587, 0.608, and 0.348 1/h to 0.083, 0.077, 0.069, and 0.063 1/h with the replacement time increased from 24 to 96 h. It has been indicated by this study that the use of CO2 emulsions is advantageous compared to the use of liquid CO2 in replacing CH4 from its hydrate.

南海南部水体和沉积物中的浮游有孔虫氧碳同位素分析

通过对2002年南海南部春季水体和表层沉积物中浮游有孔虫的δ^18O和δ^13C分析，初步探讨该区有孔虫氧碳

Far-field and beam characteristics of vertical-cavity surface-emitting lasers

We have determined the far-field patterns and beam parameters of vertical-cavity surface-emitting lasers (VCSELs) with different structures. The results show that the window diameter and the active-layer aperture of VCSELs strongly influence laser far-field distributions and beam characteristics; for VCSELs with small window omega=5 mu m, only one dominant lobe has been observed in the far-field profiles, even though injected current was increased up to 2 Ith; and the smaller the ratio of the window diameter to the active-layer aperture, the larger is the far-field divergence. The laser structure dependence of the K factor has also been studied. (C) 1996 American Institute of Physics.

Optimization of Global Signal Networks for Island-Style FPGAs

We present a staggered buffer connection method that provides flexibility for buffer insertion while designing global signal networks using the tile-based FPGA design methodology. An exhaustive algorithm is used to analyze the trade-off between area and speed of the global signal networks for this staggered buffer insertion scheme, and the criterion for determining the design parameters is presented. The comparative analytic result shows that the methods in this paper are proven to be more efficient for FPGAs with a large array size.

Analysis for temperature and pressure fields in process of hydrate dissociation by depressurization

An improved axisymmetric mathematic modeling is proposed for the process of hydrate dissociation by depressurization around vertical well. To reckon in the effect of latent heat of gas hydrate at the decomposition front, the energy balance equation is employed. The semi-analytic solutions for temperature and pressure fields are obtained by using Boltzmann-transformation. The location of decomposition front is determined by solving initial value problem for system of ordinary differential equations. The distributions of pressure and temperature along horizontal radiate in the reservoir are calculated. The numeric results indicate that the moving speed of decomposition front is sensitively dependent on the well pressure and the sediment permeability. Copyright (C) 2010 John Wiley & Sons, Ltd.

汾河景区垂柳主要虫害的生态防治对策

在研究汾河景区垂柳柳厚壁叶蜂生物学特征的基础上,通过对柳厚壁叶蜂种群数量的调查,分析了该虫在羽化产卵阶段与垂柳生长期的耦合过程、新老树种虫害程度的差异及其与环境的关系.结果表明:柳厚壁叶蜂对垂柳最大危害的枝条是从第1叶片到第6叶片的生长期;柳厚壁叶蜂种群在草地覆盖条件下密度较大.最后对汾河景区防治柳厚壁叶蜂的危害,提出了生态防治对策.

含油废水处理工艺中细菌多样性

从辽河油田曙光污水处理厂含油废水样品中直接抽提细菌总DNA,并对总DNA中16SrRNAV3可变区序列作PCR扩增、变性梯度凝胶电泳(DGGE),与常规水质分析相结合对系统中不同处理阶段细菌种群多样性和水质之间的关系进行分析。结果表明,处理系统的不同处理阶段细菌的多样性有明显差异,既存在共同的细菌种属,也存在着各自独特的细菌种属,且细菌种群的多样性与水质CODcr和总石油烃(TPH)的浓度呈负相关,细菌种群的多样性越高,CODcr和TPH的浓度越低,反之则越高。在处理过程中,随着样品中细菌多样性的增加,种群结构之间的相似性指数(Cs)逐渐升高,最后形成了稳定的种群结构。