Development of a propulsion system for a biomimetic thruster

We studied theoretically and experimentally a biomimetic propulsion system inspired by the motility mechanisms of bacteria such as E. coli. Our goal was to investigate the effect of the "complex" filament of Rhizobium Meliloti bacteria on thrust force. The complex filament is a helically perturbed filament,similar to a plain filament threaded through a small helix. The propulsive performance of this system was estimated by modeling the dynamics of helical wave motion in viscous fluid. The model consists of a helical filament which is axially rotated at angular velocity ω. Resistive force theory(RFT) was applied to this model to calculate the thrust force and required torque. The Buckingham PI theorem(non-dimensional analysis) was also used to analyze the theoretical results. The procedure for making a complex filament with various pitch angles θs from a small helix and plain filament is explained in detail. To validate the theoretical results for helical wave propulsion and compare the characteristics of complex and plain filaments together,an experiment was performed to measure the thrust forces in silicone oil. The experimental results agreed with the theoretical values predicted by RFT. The thrust forces of complex filaments depended on the shape of small helix winding. The maximum thrust force was achieved at a small helix pitch angle of θs = 45°. In addition,we found that the thrust force generated by a complex filament had a value about 10% higher than that of a plain filament with the same equivalent diameter de.     

丁苯酞-羟丙基-β-环糊精包合物的制备与表征

设计正交试验确定冷冻干燥法制备丁苯酞—羟丙基-β-环糊精包合物的最佳条件,通过薄层色谱法(TLC)、紫外光谱法(UV)、红外光谱法(IR)、差示扫描量热法(DSC)、热重分析法(TGA)考察所制备的丁苯酞与羟丙基-β-环糊精(HP-β-CD)包合前后的变化.结果表明:TLC,UV,IR,DSC,TGA可以表征包合物的形...     

从参考咨询到信息咨询的转型服务

介绍了信息咨询的分类及服务内容，探讨了了参考咨询服务的深化问题。     

数学认知结构与数学概念的学习——以高等数学的概念学习为例

随着教育理念由行为主义到认知主义的发展,数学能力的提高有待于对概念理解的强化越来越成为共识。数学概念是数学的逻辑起点,是学生认知的基础,是数学思维的核心。基于数学认知结构与数学概念学习的关系,探讨了高等数学概念学习的理论与实践,以期促进高等数学概念的学习。     

历史性住区改造适宜技术措施探讨

以北京京棉二厂职工宿舍区的保护性改造为例,集中研究与讨论了有历史保存价值的既有住宅的保护与改造,以及轻型木结构建造技术在旧住宅改造中的应用.从建筑学的角度探索解决问题的对策,以推进城市的发展与社会文明的进步.     

直觉模糊集熵的一种计算公式

为进一步精确度量直觉模糊集的模糊性,改进了直觉模糊集的模糊度的公理化形式,并给出了直觉模糊集的模糊度计算公式.利用直觉模糊集的模糊度和犹豫度,给出了直觉模糊集熵的计算公式,并举例验证了该计算公式的有效性.     

用于多电压域设计的双向全摆幅电平转换器

提出了一种无静态漏电流的高性能电平转换器．与现有的电平转换器不同,此设计能够在无静态功耗的情况下,将阈值电压转换为全摆幅输出,只要输入电平高于输出端电压域的NMOS的阂值电压即可正常工作,并且具有更短的传播延时和更低的动态功耗．此设计具有通用性,其电平转换范围仅受限于半导体工艺．针对40nm工艺实现了该电平转换器电路,并且用SPICE模型进行了仿真．仿真结果显示：该电平转换器能够在无静态功耗的情况下,将0．9V的输入电平转换为输出端电压域的工作电平1．8V,传播延时仅为200ps．     

电子-空穴气屏蔽影响下有限深量子阱中电子与空穴的本征态

考虑电子-空穴气屏蔽的影响,研究了有限深量子阱中电子和空穴的本征能量及其相应的各级本征态.电子-空穴气引起的极化电场由泊松方程给出,而电子和空穴则满足考虑极化电场下的薛定谔方程,因此本文自洽计算了泊松方程与薛定谔方程.数值结果表明,内电场使电子和空穴向相反方向靠近势垒,而电子-空穴气将屏蔽内电场使得电子和空穴向阱中心靠近;势垒、内电场和屏蔽之综合效应将影响电子和空穴的本征能量和本征波函数.本文的方法还可推广到求解任意势中的定态薛定谔方程.     

PET纤维上SuMA的紫外光接枝及对蛋白质的固定化

通过使用ＮａＩＯ４而不需除氧的条件下,利用紫外光接枝技术,成功地将ＳｕＭＡ或ＳｕＭＡ和ＨＥＭＡ二元单体共接枝到ＰＥＴ纤维上。在相同ＳｕＭＡ单体浓度下,ＨＥＭＡ的加入能显著提高ＳｕＭＡ的接支率。