Form selection of concomitant polymorphs: A case study informed by crystallization kinetics modeling

Molecular mechanisms and process kinetics of crystallizing concomitant polymorphs remain poorly understood. Solvent-mediated phase transformation and concomitant crystallization are difficult to be distinguished in practice, as multiple forms can be detected at the same time. Herein, we developed a population balance model to simulate a concomitant crystallization process of two polymorphs of tolfenamic acid. Our kinetic modeling aims to understand concomitant crystallization and help guide form selection of such a molecular system. Crystallization kinetics of ethanolic solutions were uncovered from induction time measurements, as well as seeded and unseeded crystallization experiments. Experimental and simulation results demonstrate that the stable form I crystallizes concomitantly with the metastable form II. The faster growing form II results in an intermediate decline in the composition of form I in crystallized samples, a characteristic feature of the concomitantly crystallized system. A four-quadrant scheme of attainable polymorph outcome was simulated under various crystallization conditions.     

基于Cortex-M4的环面蜗杆检测仪的全闭环控制系统

针对环面蜗杆检测仪系统控制及定位精度的需要,采用Cortex M4作为主控制器,控制步进电机驱动载物台运动,步进电机采用闭环控制。光栅尺实时检测XYZ导轨的位置信息,并把光栅信号作为反馈信号,构成闭环运动控制系统,实现坐标系中XYZ轴的运动和时栅转台旋转的高精度定位。步进电机的驱动采用软硬件细分方法,克服了步进电机爬行和丢步现象。实验表明：该系统采用全闭环控制、步进电机软硬件细分方法,实现了三坐标轴±2 μm 的精密定位,保证了环面蜗杆检测仪的准确测量。     

基于遗传算法的蜗杆蜗轮优化设计

以蜗轮的有色金属齿圈体积最小为目标函数,并从设计经验本身、运动性能、边界条件等方面建立合理的约束条件,建立了蜗轮齿圈的优化设计数学模型。应用MATLAB遗传算法工具箱寻求全局最优解。优化结果表明,采用遗传算法能够快捷有效地对蜗杆齿轮进行优化设计,是对蜗杆齿轮优化设计的一种有效方法。     

面向多样化服务定制的多态路由机制研究

如何基于有限且确定的路由结构来支持多样化服务是当前研究面临的问题,采用路由结构的自组织和自调节来实现路由与业务的“自适配”,提出一种面向多样化服务定制的多态路由机制。该机制通过自适配网络路由结构的基本“微内核”,实现到个性化定制寻址路由结构的派生与重载,使网络具有动态适应多样化业务的路由服务功能,并且支持多样网络寻址与路由的多模多态共存。     

基于马尔可夫链的网络蠕虫传播模型

提出了网络蠕虫的随机传播模型。首先,基于马尔可夫链对于网络蠕虫进行了建模,并且讨论了模型的极限分布以及平稳分布的存在性。然后,讨论了网络蠕虫在传播初期灭绝的充要条件以及在传播后期灭绝的必要条件。最后,讨论了网络蠕虫的传播规模。仿真实验对于模型进行了验证,讨论了模型中传播参数,时间参数以及漏洞主机数等相关参数对于网络蠕虫传播的影响,并且与G-W模型进行了数据对比,说明了本模型的优势。     

Development of insertion-type peristalsis pump using pneumatic artificial muscles

This study aims to develop a new type of peristaltic pump that transports high-viscosity and solid–liquid mixture fluids. Pumps capable of transporting such fluids are essential in various situations such as factory transportation, outdoors, and emergencies. These fluids are conventionally transported by positive-displacement and rotodynamic pumps. However, solid–liquid fluids could collide with the impeller of the rotodynamic pump and thereby damage the pump, whereas the positive-displacement pump must be sufficiently large to apply high pressure to the transported fluid. A small pump that can transport these fluids would save factory space and enable outdoor applications such as dredging operations. Thus, we adopted earthworm peristalsis as a model mechanism of fluid transport within a standard plumbing infrastructure. The insertion-type peristaltic pump developed in this study uses an artificial rubber muscle to achieve an earthworm-like mechanism. The capability and energy efficiency of the mechanism is evaluated in water transportation experiments.     

分度蜗杆副制造品质的提高方案

介绍了某厂滚齿机、插齿机、数控回转工作台等产品的关键部件——分度蜗杆副的制造,系统地分析了从设计图样、工艺路线、加工设备直至刀具、检验测量各个环节存在的问题,提出了攻关方案并付诸实施,取得了很好的成绩,制造精度由6~5级提高至4级。     

蜗杆斜齿轮传动重合度的研究

以汽车座椅角度调节驱动器为例介绍金属蜗杆与塑料斜齿轮传动副的应用。在参考文献的基础上推导出蜗杆斜齿轮传动重合度公式,分别绘制出压力角an、齿顶高系数han、变位系数x、蜗杆分度圆导程角γ、斜齿轮齿数z2对重合度的曲线图并分析各参数对重合度的影响。     

平面包络环面蜗杆理论及技术发展综述

平面二次包络环面蜗杆副由于其优异的性能成为当代蜗杆传动的皇冠,新型传动的代表.曲率修型原理的提出,解决了平面包络环面蜗杆的核心理论和最优齿形的问题;计算机技术在平面包络环面蜗杆的设计、制造中的应用取得了突破性的成果,优化设计和数字仿真解决了平面包络环面蜗杆副几何参数和工艺参数设计的难题;多年来一直成为平面包络环面蜗杆副推广障碍的参数系列化、标准化得到初步解决;滚刀CAD和辅助工艺设计极大地提升了工作效率;成套加工设备和工装的开发为平面包络环面蜗杆副的制造提供了良好的硬件;数控加工软件和技术的开发必将成就平面包络环面蜗杆的智能制造.新的理论和技术对环面蜗杆的推广应用将起到很好的促进作用.