Thermal cycling and hot corrosion behavior of a novel LaPO4/YSZ double-ceramic-layer thermal barrier coating

LaPO₄ powders were produced by a chemical co-precipitation and calcination method. The ceramic exhibited a monazite structure, kept phase stability at 1400?°C for 100?h, and had low thermal conductivity (~ 1.41?W/m?K, 1000?°C). LaPO₄/Y₂O₃ partially stabilized ZrO₂ (LaPO₄/YSZ) double-ceramic-layer (DCL) thermal barrier coatings (TBCs) were fabricated by air plasma spray. The LaPO₄ coating contained many nanozones. Thermal cycling tests indicated that the spallation of LaPO₄/YSZ DCL TBCs initially occurred in the LaPO₄ coating. The failure mode was similar to those of many newly developed TBCs, probably due to the low toughness of the ceramics. LaPO₄/YSZ DCL TBCs were highly resistant to V₂O₅ corrosion. Exposed to V₂O₅ at 700–900?°C for 4?h, La(P,V)O₄ formed as the corrosion product, which had little detrimental effect on the coating microstructure. At 1000?°C for 4?h, a minor amount of LaVO₄ was generated.     

某高速匝道独柱墩连续箱梁桥横向抗倾覆稳定性分析

针对独柱墩连续箱梁桥在汽车超载或偏载作用下横向易失稳的问题，总结了横向失稳坍塌的过程，分析了其失稳机理，然后阐述了独柱墩桥横向失稳的判别准则和计算方法，并对某高速匝道独柱墩连续箱梁桥进行分析，验算了其横向倾覆安全系数、支座脱空和支座转角，验算结果表明其横向倾覆稳定性满足安全运营的要求。     

钢桥静载试验结果偏差原因分析

某钢结构人行天桥的静载试验结果与理论分析结果偏差较大,为查找原因,首先深入分析试验结果的特征,推断出其主要原因,然后通过进一步的有限元理论分析证明了这种推断的准确性,最后还讨论了这种偏差导致结构受力的变化。     

Air exchange rates and migration of VOCs in basements and residences

Basements can influence indoor air quality by affecting air exchange rates (AERs) and by the presence of emission sources of volatile organic compounds (VOCs) and other pollutants. We characterized VOC levels, AERs, and interzonal flows between basements and occupied spaces in 74 residences in Detroit, Michigan. Flows were measured using a steady‐state multitracer system, and 7‐day VOC measurements were collected using passive samplers in both living areas and basements. A walk‐through survey/inspection was conducted in each residence. AERs in residences and basements averaged 0.51 and 1.52/h, respectively, and had strong and opposite seasonal trends, for example, AERs were highest in residences during the summer, and highest in basements during the winter. Airflows from basements to occupied spaces also varied seasonally. VOC concentration distributions were right‐skewed, for example, 90th percentile benzene, toluene, naphthalene, and limonene concentrations were 4.0, 19.1, 20.3, and 51.0 μg/m³, respectively; maximum concentrations were 54, 888, 1117, and 134 μg/m³. Identified VOC sources in basements included solvents, household cleaners, air fresheners, smoking, and gasoline‐powered equipment. The number and type of potential VOC sources found in basements are significant and problematic, and may warrant advisories regarding the storage and use of potentially strong VOCs sources in basements.     

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。     

大流动性混凝土在系杆钢管拱桥中的施工控制

结合北澄子河大桥的施工着重介绍自密实混凝土的配合比设计、原材料、模板质量、浇筑方法、预埋件固定等一系列施工控制措施，以确保浇筑的顺利进行和构件的施工质量。     

广义铰接板法分析弯桥

本文基于铰接板法原理,考虑各曲板梁的弯扭耦合效应及其跨长的横桥向变化,导出弯板桥荷载横向分布的简化分析公式。其计算值与模型桥加载试验结果相符较佳。     

逆变器短路控制式串级调速系统在发电厂排煤粉机90kW绕线式异步电动机上的应用

本文介绍了逆变器短路控制式串级调速系统在本钢发电厂排煤粉机00kW绕线式异步电机上的应用,文中介绍了该串调系统的工作原理,实际构成,工业实验结果及体会。     

一种不失控的三相桥式半控整流电路

本文叙述了在三相桥式半控整流电路的基础上由整流二极管、电阻及电容组成的零线电路构成的一种不失控的三相桥式半控整流电路的工作原理。该电路线路简单,元件少,造价低,它在发电机的可控硅励磁系统中有着广阔的应用前景。     

冲天炉气氛监控仪的研制与应用

本仪器以惠斯登电桥原理的热导式气体检测装置为主要部件，并附有连续抽气、过滤冷却和排除干扰气体的吸附装置等组成部分．它不仅能对熔炼全过程的炉气中ＣＯ２的成份进行准确而迅速地测量与显示，而且能通过排除干扰气体的测量，间接地测出气氛中氢气含量的多少．本仪器在生产实践中使用证明：炉气中ＣＯ２含量的相对变化与铁水过热温度有明显的对应关系，用本仪器所指示的ＣＯ２含量的变化规律对炉况进行监控是行之有效的手段．