X射线不透性体温固化聚氨酯髓核假体材料的研究

为了制备X光可显影且可以体温固化的聚氨酯,合成了N,N'-双(1,3-二羟基丙基)-2,3,5,6-四碘对苯二甲酰胺(BDTIP)含碘四元醇,将其作为聚氨酯固化的交联剂和X光显影剂,与聚氨酯预聚物混合反应得到一种新的可用于人工髓核假体的材料.利用红外光谱监测BDTIP的反应程度;利用X射线对不同BDTIP含量的聚氨酯材料的显影效果进行评定;利用噻唑蓝(MTT)比色法测试材料细胞毒性,并对具有不同碘含量聚氨酯材料的力学性能进行了对比研究.结果表明,碘的加入对聚氨酯的显影效果有很好的促进作用,较低碘含量(0.2 wt%)的聚氨酯材料即有较好的X光显影效果,而且此时聚氨酯依然保持较好的力学性能;MTT法测试表明含BDTIP的聚氨酯材料不具有细胞毒性.     

A problem of Baernstein on the equality of the -harmonic measure of a set and its closure

A. Baernstein II (Comparison of -harmonic measures of subsets of the unit circle, St. Petersburg Math. J. 9 (1998), 543-551, p. 548), posed the following question: If is a union of open arcs on the boundary of the unit disc , then is , where denotes the -harmonic measure? (Strictly speaking he stated this question for the case .) For the positive answer to this question is well known. Recall that for the -harmonic measure, being a nonlinear analogue of the harmonic measure, is not a measure in the usual sense.

The purpose of this note is to answer a more general version of Baernstein's question in the affirmative when . In the proof, using a deep trace result of Jonsson and Wallin, it is first shown that the characteristic function is the restriction to of a Sobolev function from .

For it is no longer true that belongs to the trace class. Nevertheless, we are able to show equality for the case of one arc for all , using a very elementary argument. A similar argument is used to obtain a result for starshaped domains.

Finally we show that in a certain sense the equality holds for almost all relatively open sets.

     

大理岩动态劈裂拉伸的SHPB实验研究

利用直径100 mm的Hopkinson压杆和薄圆形铝片作为波形整形器,用不同弹速径向冲击平台巴西圆盘试样以研究大理岩的动态拉伸强度。分析了试样的应变率、破坏时间、破坏模式,以及破坏过程中的载荷-应变关系,得到了关于大理岩在高应变率下拉伸强度及弹性模量的一些结论。考虑了试样的尺寸大小及两个平台附近应力的时间不均匀性与空间不均匀性对实验结果的影响。同时,利用有限元法对平台巴西圆盘试样的动态应力分布进行了数值模拟,验证了动态劈裂拉伸实验的有效性。     

Mathematical Analysis of the Formation of Molecule Sizes on a Spinning Disc Reactor

A mathematical analysis of the behaviour of the molecular weights of addition polymers during a polymerisation process is described. Spinning disc reactor (SDR) technology has been shown to yield significant improvements in terms of polymerisation rates whilst retaining close control of the molecular weights and the molecular weight distributions^[1,2]. However, understanding of the kinetics of the polymerisation process on a SDR remains unresolved. One of the questions to be addressed concerns the sizes of the macromolecules preferably formed during the polymerisation process. To address this question, a mathematical analysis of the observed trends in number and weight average molecular weight, monomer concentration and polydispersity during the polymerisation process on a SDR has been undertaken. To validate the results, experimental data obtained from benzoyl peroxide initiated free radical polymerisation of styrene on a SDR^[2] was used. It was concluded that most of the monomers consumed are in the growth of smaller size chains.     

Phase optical elements for widening a minimum diffraction spot

An iterative technique has been developed for calculating phase radial optical elements characterized by a small number of phase gradations and aimed at stretching a minimum diffraction spot. The proof of the algorithm convergence is given and the results of computer simulation are reported.     

油罐光纤传感液位测量系统的研究

采用先进的光纤传感技术在人工浮子液位计的基础上研制了一种新型的液位测量系统。系统利用力平衡原理测量液位,利用光纤传感器探测和传输信号,采用自制的光学编码盘实现光信号的调节。测试结果表明,在0~1000mm测量范围内,测量误差≤±6mm,相对误差<2%。现场应用表明,该系统的各项性能指标符合生产要求,运行稳定,性能可靠。