基于奇偶树型交互学习机与遗传算法的密文优化系统

为使图像加密系统具备优化功能,并解决当前遗传算法无法实现全局最优、收敛速率慢等问题,提出奇偶树型交互学习机耦合全局离散遗传算法的密文优化系统。定义权值更新机制,耦合混沌映射,构造奇偶树型交互学习机及其互扰模型。将切断型轮盘赌择取机制引入均匀交叉算子中,以图像分块的相邻像素相关系数和密文信息熵为目标,根据权重理论设计加权适应度函数,提出一种全局离散遗传算法,最终形成"初始加密-密文优化"的加密结构。实验结果表明,与超混沌算法、离散遗传算法、元胞自动机相比,该系统的加密质量较好,并且具备全局优化功能,可优化所有迭代结果,使最终输出密文的信息熵最大,相关系数最小。     

FO-CA:一种基于距离差异度组合权重的多属性数据分类方法

为了解决多属性数据分类问题,提出了一种基于模糊优选模型与聚类分析的分类方法(FO-CA)。首先由模糊优选模型得到有序综合指标数据集,其中在权重阶段提出了距离差异度并以此为依据构建了一种组合主客观权重的赋权方法;然后采用聚类分析将有序综合指标数据集聚类为几个簇进而分类;最后选取UCI中的Iris、Wine和Ruspini 3个数据集进行仿真实验。实验结果表明,该分类方法相比模糊优选方法及K-Means算法能获得更好的分类结果,对决策者有一定的参考价值。     

Thermal properties measurements of renatured gelatin using conventional and temperature modulated differential scanning calorimetry

The thermal properties of amorphous gelatin films and gelatin films with renatured structural order were measured by using conventional and temperature modulated differential scanning calorimetry (DSC). Different amounts of gelatin structural order associated with a melting enthalpic change in the DSC measurement were prepared based on different gelatin drying conditions. Two consecutive heating and cooling DSC measurements on the gelatin films showed that there was no change in the glass‐transition temperature (T_g) for the amorphous gelatin but there was a decrease in the T_g for the structural gelatin on the second DSC scan. This decrease was attributed to the plasticizing effect from the release of originally hydrogen‐bonded water associated with the structural gelatin. In addition, a reversing endotherm observed upon melting of the structural gelatin during a temperature modulated DSC measurement indicated that the transition of bound water to free water occurred as the partial triple‐helix gelatin melted. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 1795–1801, 2006     

Oxygen enrichment from air through multilayer thin low‐density polyethylene films

Several multilayer thin low‐density polyethylene (LDPE) films were fabricated by blown thin film having a thickness of 7 μm and an area of 130 cm². They were characterized for their oxygen‐enrichment performance from air by a constant pressure–variable volume method in a round permeate cell with an effective area of 73.9 cm². The relationship between oxygen‐enrichment properties, including oxygen‐enriched air (OEA) flux, oxygen concentration, permeability coefficients of OEA, oxygen, nitrogen, as well as separation factor through the multilayer LDPE films, and operating parameters, including transfilm pressure difference, retentate/permeate flux ratio, temperature, as well as layer number, are all discussed in detail. It is found that all of the preceding oxygen‐enrichment parameters increase continuously with an increase of transfilm pressure difference from 0.1 to 0.65 MPa, especially for the trilayer and tetralayer LDPE films. The oxygen concentration and separation factor appear to rapidly increase within the retentate/permeate flux ratio below 200, and then become unchangeable beyond that, whereas the OEA flux and the permeability coefficients of OEA, oxygen, and nitrogen seem to remain nearly constant within the whole retentate/permeate flux ratio investigated, especially for the monolayer and bilayer LDPE films. The selectivity becomes inferior, whereas the permeability becomes superior, as the operating temperature increases from 23 to 31°C. The highest oxygen concentration was found to be 44.8% for monolayer LDPE film in a single step with air containing oxygen of 20.9% as a feed gas and operating pressure of 0.5 MPa at a retentate/permeate flux ratio of 340 and 23°C. The results demonstrate a possibility to prepare an oxygen‐enriching membrane directly from air, based on the easily obtained thin LDPE films. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 3013–3021, 2002; DOI 10.1002/app.2331     

预加氢反应器的制造和检验

本文介绍了预加氢反应器的典型结构,分析了制造上的难点,有针对性地提出了解决难点的特殊工艺方案,记录了实际制造经验数据,对类似设备的制造有着重要的参考价值。     

Biochemical,functional, and histochemical effects of essential fatty acid deficiency in rat kidney

The present study was designed to examine the effects of EFA deficiency (EFAD) on biochemical, functional, and structural aspects of the kidney in growing and adult rats fed a normal or EFAD diet for 9 wk after weaning. Food and fluid intake (FI), urine volume, and Na⁺ and K⁺ excretions were measured weekly from weeks 4 to 8 by placing the rats in individual metabolic cages for 24 h. At week 9, Li⁺ and a 5% water load, respectively, were administered at 14 and 1.5 h prior to glomerular and proximal tubular function studies, as assessed by 3-h creatinine (C_Cr) and Li⁺ (C_Li+) clearances. Hematocrit and urine volume; serum and urine [Cr], [Li⁺], [Na⁺], and [K⁺]; and renal FA distribution were also measured. Data [corrected to 100 g/body weight (bw) and presented as means ±SEM] were significant, at P<-0.05. Despite a similar ingestion of solids from weeks 4 to 7 (weeks 7 to 10 of life), the rats on the EFAD diet showed a decreased body weight from week 5. From weeks 4 to 8, Fl and urine volume were similar for both groups, but the Fl increased at week 6 in the EFAD group; 24-h Na⁺ and K⁺ excretions were similar at all weeks, except for an increase in the EFAD group for both ions at week 7. In the EFAD group, C_Cr and C_Li+ decreased by 27 and 56.3%, respectively (385.7±33.4 vs. 280±21.1, and 21.0±2.1 vs. 9.2±1.1 μL/min/100 g; n=9 vs. 10), the latter result suggesting increased proximal reabsorption. The 3-h Na⁺ and K⁺ excretions were similar, but the Li⁺ decreased (0.78±0.06×10⁻² vs. 0.32±0.03×10⁻² μeq/min/100 g) in the EFAD group, giving additional support to the suggestion. Renal structure was normal and similar for both groups, but the EFAD group showed a more prominent proximal tubule brush border, together with heavier periodic acid-Schiff staining in all specimens from weeks 5 to 9. In the EFAD group, FA of the n−9 and n−7 series were higher, but most of the n−6 series were lower as a percentage of total lipids in the medulla and cortex. Medullary levels of 20∶4n−6 were maintained, 22∶4n−6 declined twice, arachidonic acid was maintained, and 20∶5n−3 was lower. The EFAD diet affected glomerular function, proximal tubular structure and function, and FA distribution in the rat kidney.     

橡胶注射成型机的特点与进展

对橡胶注射成型机主要部分的结构进行了评述，并对橡胶注射成型工艺的发展状况了简述。     

Deformation behavior of styrene-block-butadiene-block-styrene triblock copolymers having different morphologies

Deformation behavior of styrene-block-butadiene-block-styrene (SBS) triblock copolymers having different morphologies was investigated. Due to the combination of different methods which provide information on different deformation levels (macroscopic, microscopic and molecular) complex deformation mechanisms for each type of SBS block copolymer (including glassy-rubber alternating lamellae, rubber cylinders in glassy matrix and hard domains in soft matrix morphology) could be revealed. In combination with tensile tests, Fourier transform infrared (FTIR) spectroscopy was successfully applied to study the change of orientation in individual phases using the absorption bands at 1493 and 966 cm⁻¹ for polystyrene (PS) and polybutadiene (PB) phases, respectively. For all the block copolymers investigated the PB phase always oriented stronger than the PS phase because of its lower Young's modulus. However, differences in orientation in both phases were influenced by an appropriate stress distribution within the specimens during deformation, which, in fact, depends on the morphology of the polymers. Additionally, atomic force microscopy revealed local morphological changes during uniaxial stretching, which, in fact, depend on the arrangement of the structural units.     

Preparation and characterizations of interpenetrating polymer network hydrogels of poly(ethylene oxide) and poly(methyl methacrylate)

Interpenetrating polymer network (IPN) hydrogels based on poly(ethylene oxide) and poly(methyl methacrylate) were prepared by radical polymerization using 2,2‐dimethyl‐2‐phenylacetophenone and ethylene glycol dimethacrylate as initiators and crosslinkers, respectively. The IPN hydrogels were analyzed for sorption behavior at 25°C and at a relative humidity of 95% using dynamic vapor sorption. The IPN hydrogels exhibited a relatively high equilibrium water content in the range of 13–68%. The state of water in the swollen IPN hydrogels was investigated using differential scanning calorimetry. The free water in the hydrogels increased as the hydrophilic content increased. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 258–262, 2003     

测量值量化的时滞系统的输出反馈控制

为了解决无线网络带宽限制的问题,信号在传输之前需要进行量化,但是量化器的引入会给信号带来一定的误差.针对时滞系统,研究测量值量化的基于观测器的输出反馈控制问题.考虑对数量化器,为了研究量化器对系统的影响,引入上行界的方法,将对数量化问题转化成鲁棒不确定问题.为了讨论系统的收敛速度,采用带有衰减系数的Lyapunov函数,得到了闭环系统的指数衰减率.采用线性矩阵不等式(LMI)的方法给出了系统满足指数稳定的充分条件以及控制器和观测器增益的表达式.应用数值仿真证明了本文算法的有效性.