Ring‐opening polymerization of lactones initiated by diphenylzinc–coinitiator systems

Diphenylzinc, alone or in combination with water and butanone as coinitiators, was used as a polymerization initiator system for a variety of lactones at varying temperatures. The resulting data indicate that the course of the polymerization is greatly influenced by the lactone structure, as well as by the molar ratio of coinitiator to diphenylzinc. When used alone, diphenylzinc exhibited high activity as an initiator in δ‐valerolactone polymerizations, although it was less efficient when used in the β‐butyrolactone and the β‐propiolactone polymerizations. Activity in the polymerization of β‐lactones was increased by adding small amounts of butanone or water. It was also observed that the diphenylzinc–butanone combination was more effective than the diphenylzinc–water mixture in the polymerizations of β‐butyrolactone and β‐propiolactone. Copyright © 2003 Society of Chemical Industry     

Acquisition and pattern recognition of spectrum information of welding metal transfer

With the creation of a pattern recognition system for metal transfer mode, this article has collected five kinds of spectrum signals in gas metal arc welding (MIG, MAG and CO₂) and take them as training samples. These samples have been pretreated by computer, several key characteristic parameters of the spectrum signal have been creatively extracted, and a corresponding recognition function and a minimum-distance-classifier have been constructed. The results show that the pattern recognition of several kinds of metal transfer modes for the metal gas arc welding can be done successfully, and relative important parameters in welding process, such as the frequency of droplet transfer and the approximate diameter of each droplet, can also be obtained.     

通用绘图软件NuSlides中的面向对象的用户界面设计

本文描述在Ｕｎｉｘ环境下开发的通用绘图软件ＮｕＳｌｉｄｅ中的图形用户界面的设计思想和实际方法。其特点是基子面向对象的技术，提供多窗口、菜单驱动、选择面板、键盘输入等多种才法。该图形用户界面具有灵活性、可扩充性和易使用性。     

Ring‐opening polymerization of D,L‐lactide by rare earth 2,6‐dimethylaryloxide

Ring‐opening polymerization of D,L ‐lactide (LA) has been successfully carried out by using rare earth 2,6‐dimethylaryloxide (Ln(ODMP)₃) as single component catalyst or initiator for the first time. The effects of different rare earth elements, solvents, monomers and catalyst concentration as well as polymerization temperature and time on the polymerization were investigated. The results show that La(ODMP)₃ exhibits higher activity to prepare poly(D,L ‐lactide) (PLA) with a viscosity molecular weight of 4.5 × 10⁴ g mol^?1 and the conversion of 97 % at 100 °C in 45 min. The catalytic activity of Ln(ODMP)₃ has following sequence: La > Nd > Sm > Gd > Er > Y. A kinetic study has indicated that the polymerization is first order with respect to both monomer and catalyst concentration. The apparent activation energy of the polymerization of LA with La(ODMP)₃ is 69.6 kJ mol^?1. The analyses of polymer ends indicate that the LA polymerization proceeds according to ‘coordination–insertion’ mechanism with selective cleavage of the acyl–oxygen bond of the monomer. Copyright © 2004 Society of Chemical Industry     

火焰图像特征在火灾数字图像识别中的运用

火焰尖角数目和圆形度是早期火灾火焰的主要特征,本文主要论述了如何在数学形态学基础上,利用火灾火焰的两个特点判断和识别早期火情。实验中,对火焰的二值图像进行开运算,即先腐蚀,再膨胀,目的是为了对火焰图像进行形态学滤波,去噪。从实验结果可以看出,该算法可以很好的识别火焰和干扰源。     

苯并口恶嗪-环氧化合物-胺类催化剂体系开环聚合反应的研究

采用TLC，GPC，1H－NMR及IR等分析方法，对苯并恶嗪－环氧化合物－胺类催化剂体系的聚合反应进行了研究，表征了产物结构，并探讨了聚合反应机理，结果表明，苯并恶唪－环氧化合物体系在胺类催化剂如苄胺，咪唑的作用下，能发生开环聚合反应，生成低分子量的聚合物。     

Determining stress intensity factors of composites using crack opening displacement

The main purpose of this paper is to find the mixed-mode stress intensity factors of composite materials using the crack opening displacement (COD). First, a series solution of the composite material with a crack was used to evaluate COD values. Then, the least-squares method was used to calculate mixed-mode stress intensity factors. This algorithm can be applied to any method that generates or measures COD values. The major advantage of this method is that COD values very near the crack tip are not necessary. Both finite element simulations and laboratory experiments were applied to validate this least-squares method with acceptable accuracy if the even terms of the series solution are removed.     

浅谈侧窗采光和门窗节能措施

充分利用天然光，改善门窗的绝热性能，是建筑节能的重点手段。     

轻便型γ能谱测井仪几个关键技术问题的探讨

为研制性能好，功能强，微机化学程度高的轻便型γ能谱测井仪，针对非油气测井工作的井口径小（〈φ６０ｍｍ）井身浅（〈１０００ｍ）等特点，探讨了γ能谱测井仪的轻便化，测量精度，信号传输技术，稳谱技术及微机化等关键技术问题。     

δ掺杂样品中空穴态的新行为

用有效质量理论研究了δ掺杂势中电子和空穴的行为。发现能量接近于δ势垒峰的空穴穿越势垒时能产生一系列谐振态。这些状态中的空穴波函数汇聚在势垒峰周围而同量子限制在势阱中的电子波函数交叠,产生光跃迁。用MBE生长的δ掺杂样品进行光调制光谱测量,发现明显的带间跃迁峰。测得的光谱峰同理论计算的能级相吻合,证实了δ势垒中空穴的新行为。