柔性铰链微操作机构的误差源分析

深入分析了微操作机构的各种误差源机理及作用规律 ,提出了减小微操作机构误差、提高操作精度的措施 ,为高精密的柔性微操作机构设计、加工及装配提供了理论依据 ,也为进行精度测试及实现控制算法打下基础     

任意铰链四杆机构运动识别与连杆曲线的实现

本文应用VisualBasic面向对象的方法,建立了任意铰链四杆机构的运动学计算模型。介绍了任意铰链四杆机构运动识别及利用鼠标事件实现其任意点连杆曲线的方法。实现了任意铰链四杆机构的运动仿真。     

基于现场总线的楼宇自动化系统研究

就基于现场总线的楼宇自动化系统所适用的硬件拓扑结构和通讯软件及控制软件的特点进行了分析,提出了较为合理的方案。对使用过程中所存在的问题做了提示,从应用的角度来讲较为实用。     

资水梯级电站施工期闸孔通航方式工程实践

有通航要求的水利水电工程施工期通航问题,是施工导流设计和工程实施期间需要妥善解决的问题之一。以资水柘溪电站以下河段修建的修山水电站、东坪水电站和株溪口水电站工程为例,介绍了施工期利用工程既有的闸孔通航并取得较好技术经济效果的实际做法。工程实践表明,利用闸孔通航,技术上是可行的,并具有导流程序简单、施工期通航工程措施费用低、电站发电时间可提前等优点,经济效益显著。其工程经验可在类似工程中推广应用。     

Robust exponential stability of uncertain discrete time impulsive switching systems with state delay

A new class of hybrid impulsive and switching models are introduced and their robust exponential stability and control synthesis are addressed. The proposed switched system is composed of stable subsystems and unstable subsystems, which not only involves state delay and norm-bounded time-varying parameter uncertainties, but also contains the impulsive switching effects between the subsystems. Based on the extension of the system dimension and the concept of average dwell time, a kind of practically useful switching rule is presented which guarantees the desired robust exponential stability. A switched state feedback controller is also given.     

Osteogenic responses to extraskeletally implanted synthetic porous calcium phosphate ceramics: an early stage histomorphological study in dogs

In this experiment, synthetic porous calcium phosphate ceramics (hydroxyapatite–tricalcium phosphate) were prepared and implanted in dorsal muscles of dogs. The purpose was to study the biological processes prior to and during the morphogenesis of bone in extraskeletally implanted porous calcium phosphate ceramics. Specimens were harvested after implantation for 7, 15, 30, 45, 60, 90 and 120 days. Decalcified and undecalcified sections were prepared for alkaline phosphatase (ALP) histochemical localization and comparative histological analysis. The results show that bone morphogenesis in the pore regions of the extraskeletally implanted ceramics follows a complex process involving clot formation, vascular invasion, granulation-like tissue formation, polymorphic cell aggregation, osteoblast differentiation and bone formation. The characteristic feature preceding bone formation was polymorphic cell aggregation on the pore inner surface and near the invading capillaries or small venules. These cells were of various sizes and shapes, and some of them were positive for ALP activity. ALP-positive cell aggregates were more numerous where capillaries or venules were close to the pore inner surface. Osteoblast differentiation occurred within the cell clusters aggregated on the pore inner surface and bone matrix was secreted in direct contact with the ceramics. During bone formation, capillaries or small venules were always found close to the developing fronts of the osseous nidi. It is suggested that those cells which first appeared near the invading vasculature, the cells which aggregated on the pore inner surface and those cells which finally differentiated into osteoblasts may be interrelated in some way.     

电解法合成高铁酸钠的实验研究

通过改变传统电极设置位置,评定影响电解效率的各因素以实现电流效率的最大化.在简化电解装置的同时,不影响电流效率的提高.实验结果表明,将传统左右式设置电极改为上下式设置电极,阴极距液面2cm,阳极距底面4cm,电流密度2mA/cm2,NaOH浓度14mol/L,温度60℃,电解1.5h,并加入搅拌的情况下电流效率最大达到58%.     

Exponential stability of switched systems with imp ulsive effect

The exponential stability of a class of switched systems containing stable and unstable subsystems with impulsive effect is analyzed by using the matrix measure concept and the average dwell- time approach. It is shown that if appropriately a large amount of the average dwell- time and the ratio of the total activation time of the subsystems with negative matrix measure to the total activation time of the subsystems with nonnegative matrix measure is chosen , the exponential stability of a desired degree is guaranteed. Using the proposed switching scheme ,we studied the robust exponential stability for a class of switched systems with impulsive effect and structure perturbations. Simulations validate the main results.     

中国镍资源全球配置研究

中国镍需求快速增长,资源缺口不断扩大,大量进口红土镍矿冶炼镍铁的配置方式受印尼禁矿令影响难以持续.境外镍资源丰富,镍产品多样且普遍过剩,中国应缩减镲铁产能,合理配置国内生产与国外进口比例,原料级产品与消费级产品进口并举,多渠道、多品种的配置镍资源.     

改性蒙脱土定型复合材料及热湿性能实验

利用十六烷基三甲基溴化铵(CTAB)对钠基蒙脱土进行改性,以优选改性蒙脱土为主体材料,以月桂酸为客体材料,通过熔融插层法制备定型复合材料.采用步冷曲线法和饱和盐溶液法分别测试复合材料的热性能和湿性能,利用“归一法”对热湿综合性能进行量化.利用XRD,FT-IR和SEM等技术对定型复合材料的孔径分布、微观形貌和组成结构进行测试和表征.结果表明:在改性阶段,改性剂(CTAB)与钠基蒙脱土的质量比为0.4∶1,加热温度70℃,加热时间为120 min时,改性效果最好;在熔融插层阶段,月桂酸质量百分比为28.6％、加热温度为70 ℃、加热时间为120 min时,定型复合材料的热湿综合性能最优.