基于显微CT的地下工程SBS防水卷材微观研究

利用X射线CT技术对地下工程SBS改性沥青防水卷材的微观结构进行研究,探讨该技术在微观研究中的适用性。通过剪取SBS防水卷材原状试样置于显微CT系统上进行扫描,获得一系列的2D显微CT切片图像,借助图像处理软件进行3D图像的重构,并进行图像处理,最后基于重构图像进行数据的统计和分析。结果表明:对试样的3D重构图像进行分析可以获得添加物颗粒的相关参数,同时可以清楚观察到试样的层状分布形态;试样各区域材料的差异性较大;等效直径60 μm是颗粒数目分布的转折点,其两侧表现出不同的分布规律;中等颗粒和大颗粒对颗粒总体积有很大贡献。研究结果证实了采用显微CT技术对地下工程防水卷材进行微观研究的可行性,为地下工程防水材料损伤及其耐久性研究提供了一种新的途径。     

Some microwave applications of BaSrTiO3 and high temperature superconductors

Abstract

The group at the University of Colorado has been working on the applications of BaSrTiO₃ and high temperature superconductors to microwave circuits and systems with support from Superconducting Core Technologies, NASA and ONR. This work has included the development of a voltage tunable oscillator, a phase shifter, and a voltage tunable phased array antenna system. An important aspect of this program is the lattice match between the high temperature superconductor and the ferroelectric materials which enables us to grow thin films of either material on each other. By choosing the appropriate barium stronium ratio we are able to obtain changes in the dielectric constant of 5 to 1 in bulk capacitors at 77 K, the liquid nitrogen boiling temperature. Phase shifts of a little less than 126° at 10 Ghz have been obtained by applying 5 volts on a one centimeter coplanar line. The proposed phased array systems should enable us to point the beam radiated from the antenna in an arbitrary direction using two control voltages of less than 50 volts. We believe this approach leads to the possibility of inexpensive electronically scannable antenna systems which could be used for mobile communications with satellites and cellular systems.     

"Effects of interest—major congruence, motivation, and academic performance on timely degree attainment": Correction to Allen and Robbins (2010).

Reports an error in "Effects of interest–major congruence, motivation, and academic performance on timely degree attainment" by Jeff Allen and Steve Robbins (Journal of Counseling Psychology, 2010[Jan], Vol 57[1], 23-35). The link to the supplemental material was incorrect. The correct link is provided in the erratum. (The following abstract of the original article appeared in record 2010-00483-007.) Using longitudinal student data from 15 four-year (n = 3,072) and 13 (n = 788) two-year postsecondary institutions, the authors tested the effects of interest–major congruence, motivation, and 1st-year academic performance on timely degree completion. Findings suggest that interest–major congruence has a direct effect on timely degree completion at both institutional settings and that motivation has indirect effects (via 1st-year academic performance). The total effects of both interest–major congruence and motivation on timely degree completion underscore the importance of both constructs in understanding student adjustment and postsecondary success. Implications for theory and counseling practice are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)