Model of cold crystallization of uniaxially oriented poly(ethylene terephthalate) fibers

The differential scanning calorimeter heating curves of uniaxially oriented poly(ethylene terephthalate) (PET) fibers with three peaks were analyzed by using a newly proposed equation. The diffusion-controlled crystallization theory is suitable for describing cold crystallization of uniaxially oriented PET fibers. A crystallization model was proposed based on the kinetic parameters obtained. The model embraces the three sub-processes of crystallization corresponding to different growth geometries. The first sub-process corresponds to the nucleation of ordered molecular segments or the radial growth of preformed nucleus, resulting in the shorter bundle-like entities. The second sub-process corresponds to further growth of the bundle-like crystallites along chain direction, resulting in the longer bundle-like entities. The third sub-process corresponds to the three-dimensional growth of crystallites relating to the random segments, resulting in the spherical entities.     

Characterization of konjac glucomannan–quaternized poly(4‐vinyl‐N‐butyl) pyridine blend films and their preservation effect

Novel polymer blends were prepared from a mixture of 2 wt % konjac glucomannan and 4 wt % quaternized poly(4‐vinyl‐N‐butyl) pyridine (QPVP) in aqueous solution and dried at room temperature for 72 h. Their structure and properties were studied by infrared, wide‐angle X‐ray diffraction, scanning electron microscopy, thermogravimetric analysis, and differential scanning calorimetry. Thermal stability in the dry state was reduced with increasing content of QPVP. Compared with QPVP film, the tensile strength of the films was improved in the dry state. The maximum value of 12.74% tensile break elongation was reached when the content of QPVP was 30%. Structural analysis indicated that clear phase separation was observed when the content of QPVP was only 50%. Results from the filmcoating preservation experiments with lychee showed that this blend film had water‐holding ability. The fruit weight loss rate and rot rate both decreased in various degrees. The potential uses of these novel polymer films could be as preservative films. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 1868–1875, 2004     

气升式内环流反应器中油滴的分散特性

本文研究了气升式内环流反应器中油滴的分散特性。以对数正态分布密度函数为油滴尺寸的分散模型,导出了油滴的Sauter平均直径解析式。对模型作了实验验证,关联了模型参数。提出了油滴的尺寸分布密度函数和Sauter平均直径的半经验式。结果表明计算值与实验值吻合良好。     

快速高吸油性丙烯酸酯树脂的合成研究

以丙烯酸丁酯与甲基丙烯酸甲酯为共聚单体，在聚合体系中引入致孔剂和大分子增容剂，采用悬浮聚合法合成了快速高吸油性树脂，考察了致孔剂用量、增容剂用量、乙酸乙酯／异戊醇混合致孔剂质量比等对高吸油性树脂吸油性能的影响。结果表明：通过引入致孔剂乙酸乙酯，不仅使树脂对甲苯和汽油的吸油率分别达到了3300％和1000％，而且吸油速度加快，2h内可达到饱和吸油；在致孔的基础上引入增容剂，可使树脂对汽油的吸收率显著提高，达到了1500％。     

嵌入式消毒柜门内衬板拉深模具设计

通过对嵌入式消毒柜门内衬板工艺分析，确定其模具加工方案，同时对试模过程中存在的问题作进一步的剖析。     

导磁体在汽车零件感应加热中的应用技术

本文简单介绍了导磁体工作的基本原理，并给出在汽车零件大规模生产中所积累的导磁体应用的一些经验，以阐明如何更有效地使用导磁体。     

EL-CID电磁铁心故障检测试验的应用研究

为了检验发电机定子铁心质量,在制造过程中和安装现场,对发电机定子铁心进行试验是必不可少的.目前国内针对定子铁心更多地是采用常规试验方法,但是常规铁损试验所需的设备容量大、试验线路复杂,而且经济性较差、效率低下.而采用电磁定子铁芯故障探测仪(EL-CID)铁心试验只需提供约4％的额定磁通量,即可完成对铁心故障的诊断,其所需的励磁电源容量较小且容易配备和携带.为了更好地利用EL-CID检测方式进行铁心质量的判定,本文通过模拟多种故障状况下的试验,论证了EL-CID的使用条件和影响因素,为实际工作中EL-CID的应用提供更好的参考依据.     

研究合金定向凝固组织的脉冲磁场设备的研制

介绍了脉冲电磁场发生设备的工作原理 ,设计等。并介绍了其如何与合金的定向凝固设备结合 ,以实现对合金的定向凝固组织在脉冲电磁场作用下的研究。     

Pure spatial rich model features for digital image steganalysis

The SRM (Spatial Rich Model) is a very effective steganalysis method. It uses statistics of neighboring noise residual samples as features to capture the dependency changes caused by embedding. Because the noise residuals are the high-frequency components of image and closely tied to image content, the residuals of different types of image regions have different statistical properties and effectiveness for steganalysis. In this paper, the effectiveness of the residuals is investigated. Then the effectiveness of the statistics collected from different types of neighboring residual samples is investigated from the FLD (Fisher Linear Discriminant) viewpoint, and ineffective, effective and high-effective neighboring residual samples are defined. The ineffective neighboring residual samples are not likely to change during embedding, and if they are counted in statistics, they may mix the features with noise and make the features impure. Pure SRM features are extracted based on neighboring noise residual sample selection strategy. Furthermore, multi-order statistical features are proposed to increase the statistical diversity. Steganalysis performances of the statistical features collected from different types of neighboring residual samples are investigated on three content adaptive steganographic algorithms. Experimental results demonstrate that the proposed method can achieve a more accurate detection than SRM.