Simple evaluation of aortic arch calcification by chest radiography in hemodialysis patients

Vascular calcification is associated with a poor prognosis in dialysis patients. It can be assessed with computed tomography but simple inoffice techniques may provide useful information. We compared the results obtained with a simple noninvasive technique with those obtained using multidetector computed tomography for aortic arch calcification volume (AoACV) in chronic hemodialysis (HD) patients. The enrolled study subjects were 63 (32 men and 31 women) maintenance HD patients. Calcification of the aortic arch was semiquantitatively estimated with a AoAC score (AoACS) on plain chest radiology. The AoACV was increased, with a mean value of 6.6 ranging from 0% to 36.5%. The coefficient of intraobserver variation was less than 2.5%. Aortic arch calcification score was highly correlated with AoACV (r=0.635, P<0.001). Multiple regression analysis showed age (F value=12.62, P<0.001) and pulse pressure (F value=4.54, P=0.037) to be significant independent determinants of AoACS. In conclusion, a simple measurement of AoACS may be useful for inoffice imaging to choose a therapeutic regimen in HD patients.     

转体施工拱桥合龙误差对全桥影响可靠度分析

探讨了转体施工拱桥合龙误差的成因,深入研究了转动轴的定位误差分析,推导出转动轴定位偏差产生跨中合龙偏差的计算公式。通过结构力学方法和平面有限元模型相结合分析了合龙误差对钢箱拱肋的力学性能影响。     

两河口水电站白孜大桥主桥设计

指出两河口水电站白孜大桥主桥为上承式钢筋混凝土空腹箱形无铰拱桥，较详细地介绍了该桥的设计及构造特点，上部结构内力计算及上、下部结构设计等，以期为类似条件下拱桥的设计积累经验。     

H型薄壁变异钢拱架施工吊装技术

基于实际工程,阐述分析了H型薄型变异钢拱架施工工程的安装工艺、吊装方案优选和验算以及支撑胎架设计与主要连接节点的施工.     

铁路特大桥单箱三室三向预应力箱梁施工技术

主要介绍了铁路双线系杆拱大跨度现浇箱梁（主跨56m、双线铁路桥）的支架、混凝土施工、预应力施工方案，并对方案进行了深入的探讨，从而找出了施工跨路现浇箱梁的最优方案，以指导类似工程的施工。     

《自承式给水钢管跨越结构设计规程》简介

本文简要介绍《自承式给水钢管跨越结构设计规程》的编写背景、主要内容、适用范围及其力学特点。同时指出规程尚有待进一步讨论的若干问题，以资修编时参考。     

均匀受压工字型等截面三铰圆弧钢拱的平面内稳定性和极限强度

采用大挠度弹塑性有限单元法对均匀受压等截面三铰圆弧钢拱的平面内稳定性和极限强度进行研究,考虑了材料非线性、残余应力、初始几何缺陷和矢跨比的影响,得到了均匀受压工字型等截面三铰圆弧钢拱的平面内稳定性设计曲线,并与国内外钢结构设计规范轴心受压构件的稳定曲线进行了对比,得出了轴心受压构件的稳定曲线不能直接用于拱的稳定性设计的重要结论。     

圆的奇特性质与应用

本文首先介绍圆是具有周长最短面积最大这一奇特性质,利用它解决多边形边长固定面积最大,及周长固定面积最大等实际问题。     

Solving Ertha Diggs’s Ancient Stone Arch Mystery

According to legend, when the Romans made an arch, they would make the architect stand under it while the wooden support was removed. That was one way to be sure that architects carefully designed arches that wouldn’t fall! Educator Michael Serra led AAAS symposium participants in a surprising and fun hands-on arch construction project using familiar objects—Chinese take-out cartons—in an unfamiliar way: “these are stone voussoirs from an ancient miniature bridge uncovered by my friend, archaeologist Ertha Diggs. She has asked us to determine the number of stones in the original bridge.” This makes it possible to understand both arch mechanics and the mathematics behind the arch through actually constructing them.     

A knowledge-based system for maintenance planning of highway concrete bridges

This paper presents a knowledge-based system that is used for maintenance planning of highway concrete bridges. The system includes functions for maintenance priority setting among bridges, feasible treatment assessment in each case, and maintenance planning for a bridge stock. Maintenance priorities are set using a scoring model with decision parameters appropriately weighted. Feasible treatments are determined based on bridge condition and other factors that accelerate deterioration. Decisions for maintenance planning result from a linear programming model and are based on priority ranking, cost and effectiveness characteristics of feasible treatments, and existing budget constraints. The system has been successfully evaluated with actual and simulated data.