Effect of composition on gelation kinetics of unfilled and nanoapatite-filled poly(lactide-ethylene oxide-fumarate) hydrogels

Oscillatory shear rheometry at small strains was used to investigate the effects of composition (concentration of macromer, crosslinker, initiator/accelerator, and filler) on the gel point and ultimate storage modulus of poly(l-lactide-co-ethylene oxide-co-fumarate) (PLEOF) hydrogels. PLEOF in situ polymerizing hydrogels can be used as biodegradable scaffolds for cell encapsulation and tissue regeneration. The time evolution of the viscoelastic properties of the polymerizing mixture during the sol-gel transition was monitored using mechanical rheometry. According to the results, while the ultimate storage modulus linearly increased with the concentration of methylene bisacrylamide (BISAM) crosslinker, the values of the storage and loss moduli at the gel point were insensitive to the concentration of BISAM. Similar behavior was observed for PLEOF hydrogels reinforced with hydroxyapatite nanoparticles.     

基于可拓学模型的大批量定制实施方法分析

简要阐述了当前企业环境的特点，分析了大批量定制及其可拓学模型；然后，从可拓学中的可拓工程出发，以“系列化”、“变型结构设计”和“变型工艺设计”为例，说明了可拓学在实施大批量定制中的应用，为企业寻找新的、有效的大批量定制实施方法提供料新的思路和工具。     

“两步法”求取双目视觉传感器中摄象机位置关系

根据平行线“消隐点”理论，提出了用于双目视觉传感器自标定的“两步法”。该方法仅需４对消隐点象面坐标便可线性求解出旋转矩阵，再用２个空间点坐标便可线性求解出平移矢量。     

直流系统接地探测的微机集散监测系统的开发

文中介绍了根据低频信号变频探测原理和计算机控制技术研制开发的直流系统接地计算机集散监测系统。该系统的开发解决了我国电力系统中直流系统接地点探测长期不能自动监测的难题。     

KINEMATIC VISCOSITY-TEMPERATURE BEHAVIOR OF HEAVY TBP-FRACTIONS (455°C+) OF ARABIAN CRUDE OILS

A generalized kinematic viscosity-temperature correlation for undefined liquid heavy petroleum fractions has been developed to represent the data for a wide range of temperature from 100°C to 200°C. The correlation is based on the experimental kinematic viscosity data of true boiling point fractions of four Arabian crude oils. The characterization property required for estimation is 50% boiling point. The proposed correlation fits the experimental data with an overall absolute error of 6.1%. Experimental measurements of kinematic viscosity of heavy true boiling point fractions of Arabian crude oils were also obtained in order to develop the proposed correlation.     

钻石型分形晶格上BEG模型的临界行为

应用实空间重整化群方法研究了分形结构 -钻石型分级晶格上BEG(Blume Emery Griffith)模型的相变和临界现象 ,得到了重整化变换的递推关系 ,确定了重整化变换的不动点 ,并且计算了临界点附近关联长度的临界指数 发现钻石型分级晶格上BEG模型的相变温度为无穷大 ,这表明系统永远处于有序态     

Development and implementation of a NURBS curve motion interpolator

This paper deals with the issues of development and implementation of a real-time NURBS interpolator for a six-axis robot. Using an open-architecture controller system as a testbed, a real-time NURBS curve interpolator was developed, implemented and tested. Sample runs were conducted with the resulting trajectories measured in real-time during robot motion. The resulting trajectories are analyzed, discussed and compared with those from a commonly used point-to-point approximation technique. The real-time NURBS curve interpolator's feasibility, advantages and related issues are also discussed.     

布尔函数的对偶性和线性点

本文主要讨论了部分自对偶和部分反自对偶函数、部分线性函数以及具有线性点的函数的性质。     

Cubic Bézier approximation of a digitized curve

In this paper we present an efficient technique for piecewise cubic Bézier approximation of digitized curve. An adaptive breakpoint detection method divides a digital curve into a number of segments and each segment is approximated by a cubic Bézier curve so that the approximation error is minimized. Initial approximated Bézier control points for each of the segments are obtained by interpolation technique i.e. by the reverse recursion of De Castaljau's algorithm. Two methods, two-dimensional logarithmic search algorithm (TDLSA) and an evolutionary search algorithm (ESA), are introduced to find the best-fit Bézier control points from the approximate interpolated control points. ESA based refinement is proved to be better experimentally. Experimental results show that Bézier approximation of a digitized curve is much more accurate and uses less number of points compared to other approximation techniques.