Spectroscopic ellipsometry characterization of high-k gate stacks with Vt shift layers

We have used spectroscopic ellipsometry (SE) to measure layer thicknesses of HfO₂/La₂O₃ and La₂O₃/HfO₂ stacks on SiO₂/p-Si. Two approaches to extract layer thicknesses from a single SE measurement were shown to be inaccurate, possibly due to similarities in the optical dispersions of HfO₂ and La₂O₃. The approach where SE data was collected after deposition of each layer and only the thickness of the top layer was determined by modeling was found to be capable of accurately measuring the thickness of each layer. These conclusions are supported by angle resolved X-ray photoelectron spectroscopy (ARXPS), X-ray reflectivity (XRR) and Rutherford backscattering spectroscopy (RBS) measurements.     

沥青面层厚度对路面结构力学指标影响分析

通过拟定不同的半刚性沥青路面结构组合,利用Bisar3.0软件进行路面结构力学计算,着重分析了路面沥青层厚度的变化对基层层底拉应力、基顶压应变以及面层剪应力的影响规律,为相关路面结构力学指标的研究提供指导。     

冰蓄冷中央空调技术的应用

结合西北某机场制冷站工程,介绍了冰蓄冷中央空调技术的实际应用,分别阐述了冰蓄冷系统的工艺原理,结构组成及施工工艺,并通过经济性分析,总结了冰蓄冷中央空调技术的优点,指出该技术前景广阔,值得推广。     

二氧化碳改造空心钢管混凝土性能研究Ⅰ:试验研究

本文考虑将干冰放置于空心钢管混凝土构件的内部空心中,干冰将逐步气化,变为二氧化碳气体,通过设计一定的试验设备来控制其压力,使得该高压气体能在较短时间内有效地渗透进混凝土中,与混凝土中的Ca(OH)2发生碳化反应.试验研究表明,该试验装置安全可靠,能使空心钢管混凝土内表面发生一定深度的碳化,为二氧化碳在改良混凝土性能的应用方面提供了一种新思路.本试验的研究内容,目前国内外还没有相关报道,属国内外首创.     

水源热泵与蓄能结合系统的评价体系研究

针对水源热泵和冰蓄冷的技术特点,确定了水源热泵与蓄能结合的系统的评价指标。对系统的经济性、节能性、安全性、环境效益、特性进行分析,提出该系统的综合评价体系。采用模糊综合评价方法,建立了评价模型,并得到相应的评价步骤。结合工程实例,分析了综合评价体系的应用结果,研究表明,综合评价体系可以全面反映该系统的特性,为方案决策和系统设计提供了量化依据。     

对地下室顶板上消防车活荷载合理取值的探讨

针对2006年版《建筑结构荷载规范》( GB 50009-2001)第4.1.1条对消防车活荷载规定的缺陷,分别以板和梁为研究对象,考虑车台数、覆土厚度、计算跨度等因素,按内力(弯矩)等值的原则,计算出不同条件下的消防车等效均布活荷载,进而归纳出适于设计应用的取值.研究表明:覆土对qe有明显的折减作用,是影响qe取值的...     

The influence of profiled sheeting thickness and shear connector’s position on strength and ductility of headed shear connector

A three-dimensional finite element model is developed, validated and used in the parametric study to investigate the influence of shear stud’s position and profiled sheeting thickness on the strength, ductility and failure modes of the headed shear stud welded to the modern profiled sheeting. A total of 240 push tests were analysed with different sheeting thicknesses, positions of the shear stud in the trough, concrete strengths and transverse spacings. The results showed that the sheeting thickness influenced the shear connector resistance of studs placed in the unfavourable position more than studs placed in favourable and central positions. The strength of the shear connector placed in the unfavourable position increased by as much as 30% when the sheeting thickness was increased. The shear connector resistance of the unfavourable stud was found to be primarily a function of the strength and the thickness of the profiled sheeting rather than the concrete strength. The strength prediction equations for unfavourable and central studs were also proposed. The results suggested that the strength of the shear connector increased as the distance of the shear stud increased from the mid-height of the deck rib in the load bearing direction of the stud. The load-slip behaviour of the studs in the unfavourable position was more ductile than the studs in the favourable position, with slip of 2-4 times higher. It was found that the increase in sheeting thickness and transverse spacing improved the ductility of the stud in unfavourable position, but had no effect on the stud in the favourable position. The failure modes suggested that the favourable and central studs failed by concrete cone failure and unfavourable studs failed by rib punching together with crushing of the narrow strip of the concrete in front of the stud.     

大管径直埋供热管道局部稳定性验算方法比较

对大管径直埋供热管道局部稳定性验算方法进行了分析比较,欧洲EN13941标准验算方法偏于保守,建议采用临界应力推导法。在满足不发生局部失稳的条件下,增大壁厚可采用冷安装。当增大壁厚后管道增加的造价低于电预热安装费用时,可采用冷安装。     

钢筋混凝土保护层厚度的控制

对混凝土保护层的主要作用进行了介绍,包括增强钢筋与混凝土之间的粘结锚固、防锈、防火等,分析探讨了混凝土结构中钢筋保护层厚度存在的各种问题,并提出了具体的质量控制措施,以确保工程的安全性和耐久性。     

浅谈沥青混合料面层的施工方法及质量控制

结合工作实践,以阳冀高速公路工程为例,对沥青混合料面层的施工方法及质量控制进行了介绍,分别对拌和、摊铺、碾压及工作缝的处理等工序作了具体阐述,对今后同类工程项目具有一定指导意义。