液氮制冷低气压试验箱的仿真设计

在采用液氮制冷的低气压试验箱的设计中,用常规工程设计方法计算的降温过程冷负荷过大,从而导致真空系统设计容量过大。本文采用分布参数模型对试验箱低气压条件下降温过程的冷负荷进行了精确仿真模拟,以此作为真空系统容量设计的基础,减小了设计规模,取得了良好的效果。     

A digital secure image communication scheme based on the chaotic Chebyshev map

In this paper, a simple image secure communication scheme based on the chaotic Chebyshev map and chaos synchronization is proposed. The scheme relies on the excellent correlation property of chaotic sequences, which is very desirable for secure image communication. The results obtained by computer simulation indicate that the transmitted source image can be correctly and reliably recovered using the proposed scheme, even through a noisy channel. Notably, the scheme possesses relatively high security and can be easily implemented. Moreover, the quality of the recovered image is satisfactory, quantified by such common criteria as the bit‐error rate performance. Copyright © 2004 John Wiley & Sons, Ltd.     

改进的深度脱木素的硫酸盐蒸煮：第一部分 用硫化钠预处理的桉树硫酸盐蒸煮

用硫化钠水溶液预处理桉树，接着进行改进的深度脱木素硫酸盐蒸煮。结果表明，在１６０℃预处理后脱木素的选择性较常规硫酸盐蒸煮有显著提高，可得到低Ｋａｐｐａ值（约为１０）的浆而没有明显的强度损失。     

宜昌地区下寒武统沉积环境分析

宜昌地区早寒武世除天柱山期(南部和西部称岩家河期)岩性变化较大外,其他依次沉积了以黑色炭质页岩夹灰岩、细碎屑岩、石灰岩、白云岩等为主的岩性组合,反映了中扬子区岩性四分的特点。晚震旦世灯影末期区内是一个东高西低、东北高西南低的浅海沉积区。在此背景上,早寒武世早期(即天柱山期)遭受了短暂而快速海进之后,依次经历了浅海盆地边缘、斜坡带、浅海陆棚及潮坪等沉积环境的缓慢演化,显示了有规律的海退序列。在区内天柱山组、岩家河组及水井沱组等均首次发现了重力流沉积;在水井沱组下部炭质页岩所夹的薄层粉晶云岩中,首次发现了沉积型重晶石富集层。根据区内天柱山期为浅海斜坡带(岩家河期为浅海盆地边缘)、水井沱期为浅海盆地边缘至斜坡带等沉积环境判断。天柱山组(岩家河组)与水井沱组之问应为连续沉积、整合接触。图3表1参7     

Convergence analysis of hybrid bi-directional associative memory neural networks with discrete delays

In this paper, the dynamical characteristics of hybrid bi-directional associative memory (BAM) neural networks with constant transmission delays are investigated. Without assuming the symmetry of synaptic connection weights and the monotonicity and differentiability of activation functions, the Lyapunov functionals are constructed and Halanay-type inequalities are respectively employed to derive the delay-independent sufficient conditions under which the networks converge exponentially to the equilibria associated with temporally uniform external inputs. Some examples are given to illustrate that the results are less conservative and less restrictive than the previously known results.     

汽油辛烷值智能调合系统

采取一种能够在线学习、不断提高、建立一系列模型的策略，提出了一种具有学习功能的汽油辛烷值智能调合系统。该系统可以根据成品汽油辛烷值指标、生产成本和市场价格等因素提供一个较好的油品调合调度方案。实际应用结果表明，利用参数学习的方法计算调合汽油辛烷值是可行的。     

毛细管微反应器中乙烯环氧化反应

在石英毛细管中涂覆α-Al2O3并负载银,制成微反应器,利用毛细管微反应器进行了乙烯环氧化反应的实验。考察了反应温度、乙烯含量、气态空速等因素对乙烯环氧化反应的影响。实验结果表明,在毛细管微反应器中可进行乙烯环氧化反应,在常压、不添加任何助催化剂和抑制剂的条件下,反应温度为230℃时,乙烯的转化率为69.54%,环氧乙烷的选择性和收率分别为82.00%和57.02%;毛细管微反应器的气态空速可达到5600h-1,超过工业装置的水平,缩短了反应时间,减小了深度氧化的几率。     

非洲爪蟾卵提取物中200nm膜泡与环形片层及核被膜上核孔复合体形成的关系

将ＬａｍｂｄａＤＮＡ引入活化的非洲爪蟾卵提取物中，在由磷酸肌酸与磷酸肌酸激酶构成的ＡＴＰ再生系统的参与下，在这种非细胞体系中能够围绕由ＬａｍｂｄａＤＮＡ诱导形成的染色质重建核被膜结构，同时在染色质外出现类似核被膜结构的环形片层。在这两种膜结构中核孔复合体的形成都与直径２００ｎｍ左右的单层圆形小膜泡密切相关，这些小膜泡可以附着在染色质表面或独立于染色质之外相互融合成扁平囊状的双层膜片层，双层膜进一步融合形成核孔，与此同时，核孔复合体在核孔上完成装配。     

Morphology and Forming Mechanism of Rare Earth Inclusions During Solidification of Steel

ＭｏｒｐｈｏｌｏｇｙａｎｄＦｏｒｍｉｎｇＭｅｃｈａｎｉｓｍｏｆＲａｒｅＥａｒｔｈＩｎｃｌｕｓｉｏｎｓＤｕｒｉｎｇＳｏｌｉｄｉｆｉｃａｔｉｏｎｏｆＳｔｅｅｌ￥ＺｈａｉＱｉ－Ｊｉｅ（ＤｅｐａｒｔｍｅｎｔｏｆＭｅｔａｌｌｕｒｇｙ，ＵｎｉｖｅｒｓｉｔｙｏｆＳ...