Investigation on Resonant Vibration Performances of Fe‐Doped BiScO3–PbTiO3 Ceramics in High‐Temperature Environment

The high‐temperature performance of a series of Fe‐doped BiScO₃‐PbTiO₃ (BSPT) piezoelectric ceramics at the morphotropic phase boundary was investigated. The effects of different Fe contents on the piezoceramics were assessed with regard to variations in structure, morphology, dielectric properties, piezoelectric properties, and high‐temperature resonant vibration. X‐ray diffraction (XRD) results indicated that the Fe‐doped BSPT ceramics show a single perovskite structure and that the c/a ratio undergoes a slight increase with increasing Fe concentrations. It was also found that, as the proportion of Fe in the ceramics was increased, the grain size was enlarged somewhat, the dielectric loss (tan δ) decreased, the mechanical quality factor (Q_m) was gradually improved, and the Curie temperature (T_C) was increased from 426°C to approximately 460°C. Despite these complex effects, it was evident that Fe doping can improve the high‐temperature resonant vibration performance of BSPT ceramics, and that these materials exhibit stable resonant vibration velocities at temperatures as high as 225°C. Our results indicate that Fe‐doped BSPT ceramics have the potential to be used as piezoelectric power devices intended for high‐temperature environments.     

地铁站域公交车换乘研究的关键问题及解决思路

地铁与公交车换乘作为地铁站域集散行人的重要交通行为,在该换乘路径上存在着换乘距离模糊、相关功能业态布局杂乱、安全性与便捷性不佳等问题.从单一评价指标切入的既有研究难以提供全面性的解决方案,致使对地铁站域空间和公交换乘行为的系统性评价和精细化研究迫在眉睫.文章以地铁站域公交换乘的空间与行为角度出发,提出技术方面、行为方面、评价体系和路径优化的研究问题,运用计算机技术对换乘空间与行为进行分析,并总结换乘优化的基本思路与方法,以期为相关规范的制定提供理论参考,助力交通基础设施建设工程研究.     

PBT非等温热分解动力学的研究

考察了聚对苯二甲酸丁二酯(PBT)在空气和氮气中的热稳定性,采用Kissinger与Ozawa法计算出PBT在空气和N_2中的热分解活化能。结果表明:PBT在空气和N_2中的热分解活化能分别为132.75,164.56 kJ/mol;热分解反应级数均在0.9以上。随着质量损失率的增大,热分解活化能增大。     

南京南郊景观调查、评价与规划研究

南京南郊生态环境优越,历史文化遗存丰富.随着南京城市发展的南移,城市建设对南郊景观的影响将逐渐加强,对南郊景观进行科学的规划迫在眉睫.该文在对南郊现状景观调查与生态评价的基础上,按照景观生态规划总体格局原理以及"斑块-廊道-基质"模式,来研究构建南郊的生态化廊道体系和开敞空间景观格局,以期使其廊道、斑块及基质等景观要素的数量结构和空间分布趋于科学合理.     

某低品位金矿石选矿试验研究

对山东某低品位金矿石进行了选矿试验研究,通过对浮选指标各影响因素的优化,得出了适合该金矿石开发的提金工艺,确定了一粗一精二扫的单一浮选工艺,可使精矿金品位达到56.25g/t、回收率达到93.31%;精矿银品位86.50g/t、回收率达到86.10%的较好指标。     

压缩载荷下复合材料整体加筋板渐进损伤非线性数值分析

建立了考虑脱粘的复合材料整体加筋板渐进损伤有限元分析模型。该模型采用界面单元模拟筋条与壁板之间的连接界面, 连接界面和复合材料层板分别采用Quads准则和Hashin准则作为失效判据, 基于ABAQUS软件, 建立了含连续损伤状态变量的材料刚度退化方案。基于该模型, 采用非线性有限元方法研究了压缩载荷下复合材料整体加筋壁板在考虑初始几何缺陷时的破坏过程, 分析了结构相应失效模式的细观损伤机制; 详细讨论了轴向刚度比对结构承载能力及破坏模式的影响。结果表明: 考虑脱粘损伤的有限元模型能有效模拟加筋板的破坏过程; 在加筋板铺层设计合理的情况下, 增加筋条与壁板刚度比能有效提高加筋板截面单位面积的承载能力。      

保障性住房设计探索

回顾和总结了自政府出台推行小户型住宅政策以来,建筑师对小面积住宅设计技术途径的探索,对典型户型的设计进行了分析总结,为中低收入的保障性住房提供借鉴。