Na0.5Bi0.5TiO3-K0.5Bi0.5TiO3系无铅压电陶瓷的制备工艺研究

利用XRD、SEM等分析技术 ,研究了Na0 .5Bi0 .5TiO3 -K0 .5Bi0 .5TiO3 系无铅压电陶瓷的合成温度 ,烧成工艺条件对陶瓷晶体结构、压电性能的影响。结果表明 ,合成温度提高有利于主晶相的形成 ,适当延长保温时间有利于材料的压电性能。该体系随着KBT含量的增加 ,烧结温度提高 ,烧结温度范围变窄。同时研究了极化工艺条件对材料压电性能的影响表明 ,提高极化电场和适当提高极化温度有利于压电性能的提高 ,但过高的温度由于受到材料高温下退极化的影响而导致材料压电性能变差     

Preparation and Catalytic Performance of Mesostructured Aluminosilicate Nano-particles with Wormhole-Like Framework Structure

A facile two-step sol–gel method has been developed for the preparation of mesostructured aluminosilicate nano-particles (Si/Al = 7.5) with wormhole-like but uniform pore structures and highly catalytic activities towards bulky hydrocarbon cracking. It is desirable that, as this synthesis takes place in the absence of alkali cations, the mesoporous nano-particulate material is directly obtained in the acid form, making a subsequent ion-exchange and calcination treatment superfluous.     

PMN-PZT压电陶瓷的凝胶注模研究

对三元系PMN—PZT压电陶瓷的凝胶注模成形工艺进行了研究,重点讨论了分散剂加入量、pH值、球磨时间与注模浆料流变之间的关系,当分散剂用量为0 .95 %～1 .0 5 % ,pH值为10 .5～11 .5 ,球磨时间为8h时,可以制备出固相含量为5 5 % ,粘度小于1Pa·s的PMN -PZT压电陶瓷悬浮体。将凝胶注模与传统模压成形工艺制备的样品进行了比较,通过扫描电镜(SEM )显微形貌分析和电学性能测定。结果表明:凝胶注模工艺制备的样品与模压工艺制备的样品相比较,其显微结构均匀致密、晶粒大小与晶界分布均匀,气孔率更小,电学性能更均匀。     

工业烧嘴冷却水管路阻力损失的计算

分析了影响工业烧嘴冷却水管道沿程阻力损失的因素,明确了沿程阻力系数是主导因素,计算了工业烧嘴冷却水管路阻力损失。检验表明,计算值与实测数据符合较好,说明计算方法可用于阻力损失的实际计算,指出螺旋管的盘绕方式和几何因素对流动阻力的影响不可低估。研究结果可为烧嘴的设计和烧嘴冷却水泵选型等提供科学依据。     

复配釜温度控制系统的DMC-PID控制

针对常规PID控制策略在复配釜內化学反应的吸热升温阶段和放热保温阶段的转折处难以取得满意控制效果的问题,提出了利用多变量动态矩阵控制(DMC)算法实现对设定温度的跟踪控制.进一步引入了DMC-PID控制策略,以改善系统的控制性能,实现了对设定温度的有效跟踪控制.最后通过试验研究,验证了本文方法的有效性.     

直接法合成甲基（氢）二氯硅烷新工艺研究

本文通过催化作用原理研究，提出了以Ｓｉ、ＣＨ＿３Ｃｌ为原料，直接法合成ＣＨ＿３ＳｉＨＣｌ＿２的新工艺．采用ＣｕＣｌ－Ｎｉ－Ｚｎ催化体系不但能使ＣＨ＿３Ｃｌ适量分解产生ＨＣｌ．而且还能促进ＨＣｌ与Ｓｉ、ＣＨ＿３Ｃｌ反应并有效地转化为目的产物ＣＨ＿３ＳｉＨＣｌ＿２，由小试和４００ｍｍ流化床中试所得的混合单体中，ＣＨ＿３ＳｉＨＣｌ＿２含量＞１５％，（ＣＨ＿３）＿２ＳｉＣｌ＿２＞５０％，为工业化生产有机硅含氢单体开辟了新的途径。     

泡沫夹层结构的模压共固化成型工艺及参数选定

在分析夹层结构的基础上,概述了常用芯材包括铝蜂窝、NOMEX蜂窝和聚甲基丙烯酰亚胺泡沫塑料的性能和特点,介绍了刚性泡沫夹层结构常用的成型工艺,详细阐述了刚性泡沫夹层结构的模压共固化成型工艺及相关参数的选定。     

环氧丙烯酸酯合成及应用的研究进展

介绍了环氧丙烯酸酯从双酯合成到双酯的改性,以及近几年新提出的单酯合成及应用的研究现状,评述了环氧丙烯酸酯,尤其是环氧丙烯酸单酯合成的研究进展。     

Bench-scale processing of amaranth seed for oil

Amaranth seed (Amaranthus hypochondriacus cv. K432) was processed to obtain oil, reported to be a promising source of squalene. The amaranth seed was ground using a stone mill, then separated into oil-rich embryonic tissue (or “bran”) and starchy perisperm. Amaranth bran was much more stable than rice bran when free fatty acid (FFA) content and peroxide value were monitored. Milling at a gap of 0.755 mm did not result in excessive damage to the starch in the perisperm fraction and yielded a bran fraction that contained more than three-fourths of the oil and a starchy fraction consisting of more than two-thirds of the seed weight. The bran particles were too fine for effective bench-scale extraction of the oil. Consequently the bran was extruded into collects prior to extraction. Two extrusion settings were evaluated regarding the rate of moisture injection, while the bran feed rates were constant. There was no significant difference in appearance or size between the two dried collets. Collets were extracted with hexane using an Armfield Extraction/Desolventizing Unit (Model FT 29, Armfield, Ltd., Hampshire, England). Oil recovery averaged 97.7 and 80.0%, respectively. Oil was extracted at high yield from the bran when the bran was extruded into collets. Oil can be obtained as a coproduct of amaranth starch by milling and separating the fractions of amaranth seed. Milling, extrusion, and extraction did not decrease significantly the squalene content in amaranth oil, but increased FFA content and peroxide value and changed tocopherol content of the oil.     

Secure and robust image hashing via compressive sensing

Image hash functions find extensive applications in content authentication, database search. This paper develops a novel algorithm for generating a secure and robust image hash based on compressive sensing and Fourier-Mellin transform. Firstly, we incorporate Fourier-Mellin transform into our method to improve its performance under rotation, scale, transition attacks. Secondly, we exploit the property of dimension reduction inherent in compressive sensing for hash design. The statistic structure and sparse of the wavelet coefficients assure efficient compression in situation of including maximum the image features. The hashing method is computationally secure without additional randomization process. Such a combined approach is capable of tackling all types of attacks and thus can yield a better overall performance in multimedia identification. To demonstrate the superior performance of the proposed schemes, receiver operating characteristics analysis over a large image database is performed. Experimental results show that the proposed image hashing is robust to a wide range of distortions and attacks. When compared with the current state-of-the-art methods, the proposed method yields better identification performances under geometric attacks such as rotation attacks and brightness changes.