Experimental Study on Seismic Performance of Through-Tenon Joints with Looseness in Ancient Timber Structures

ABSTRACT

In order to study the influence of looseness on seismic performance of through-tenon joints, six through-tenon joints specimens in 1:3.2 scale, including one tight-fitted joint and five loose joints, were fabricated according to the Engineering Fabrication Methods of Qing dynasty. The failure modes, mechanical behaviors such as the hysteresis and envelope curves, strength and stiffness degradations, energy dissipation, and deformation of the specimens under low cyclic reversed loading tests were analyzed. Results show that the failure modes of theses joints under positive and negative loadings are bending damage on the big tenon head and tearing damage on the variable cross-section, respectively. The hysteresis curves of joints appear to be anti-Z shape and present typical pinching effect. The greater the degree of looseness is, the more obvious the slippage is. The bending moment, stiffness and energy dissipation of loose joints are lower than those of the tight-fitted joint under the same rotation angle, and the increase in the loose degree cause them to gradually decrease. Meanwhile, the behavior of the through-tenon joints is further simulated by the nonlinear finite element analysis program, and the test results agree well with the numerical analysis results.     

Geographically Weighted Cox Regression for Prostate Cancer Survival Data in Louisiana

The Cox proportional hazard model is one of the most popular tools in analyzing time-to-event data in public health studies. When outcomes observed in clinical data from different regions yield a varying pattern correlated with location, it is often of great interest to investigate spatially varying effects of covariates. In this paper, we propose a geographically weighted Cox regression model for sparse spatial survival data. In addition, a stochastic neighborhood weighting scheme is introduced at the county level. Theoretical properties of the proposed geographically weighted estimators are examined in detail. A model selection scheme based on the Takeuchi’s model robust information criteria is discussed. Extensive simulation studies are carried out to examine the empirical performance of the proposed methods. We further apply the proposed methodology to analyze real data on prostate cancer from the Surveillance, Epidemiology, and End Results cancer registry for the state of Louisiana.     

一种基于形状和颜色特征的建筑彩画检索方法

为了能够在建筑彩画数据库系统中自动找出与所给事例彩画相似的彩画及各种相关数据资料,需要进行彩画图像检索。给出了一种基于形状和颜色特征的建筑彩画检索方法,第一步是对彩画基本类型进行检测识别,先对彩画图像进行边缘检测,再利用先验模板对边缘图像进行匹配,然后根据匹配结果来识别彩画的基本类型。第二步是在相同的基本类型中进行相似性匹配,主要是在HSV空间中统计颜色直方图特征矢量,以同类型彩画之间颜色直方图矢量的相似度大小作为检索依据,最后给出检索结果。实验表明,本方法的检索结果更符合人眼对相似性的感知。     

基于时空间行为的混合住房社区社会分异的研究框架

混合住房社区内的社会分异是城市社会分异的新形式，是城市地理学者面临的新研究议题，也是在促进社会融合过程中亟待解决的问题。以居住区分异为核心的研究范式平均化了“邻里效应”，无法揭示同一居住区内部的社会分异。居民时空间行为研究为揭示社区内部的社会分异提供了理论和方法支撑。本文首先回顾混合住房社区政策的起源、发展及学术界关于居住混合与社会融合关系的争议，然后对目前国内外关于混合住房社区的研究进行综述，接着讨论了从时空间行为视角透视社会分异问题的有效性，并基于已有研究进展构建了基于居民时空间行为的混合住房社区社会分异的研究框架，以期为混合住房社区政策制定和城市社区管理提供参考。     

Fast Nonlinear Analysis of Traditional Chinese Timber-Frame Building with Dou-Gon

ABSTRACT

This article presents a study of the applicability of fast nonlinear analytical (FNA) models in predicting the global response of Chinese traditional timber-frame building with Dou-Gon under seismic excitation. Efforts are made to overcome challenges in establishing simplified calculation models, and the corresponding dynamic equations are derived considering the mechanical behavior of sliding column root, mortise-tenon joint and Dou-Gon (bracket sets). Furthermore, nonlinear time-history analysis is conducted under different seismic excitations. Through a verification study, a good correspondence is obtained with previous shake-table test results. Seismic response analysis is also conducted to investigate the energy dissipation of column root sliding, mortise-tenon joint, and Dou-Gon. Subsequently, peak responses of column root and roof under increased values of peak ground acceleration (PGA) are also analyzed. And then, seismic isolation ability and damping characteristics of the model are discussed.     

中国传统村落文化景观研究进展与展望

传统村落文化景观作为特定地域范围内具有乡土文化气息的自然与人文因素综合体，承载着中华农耕文明的精髓，具有“传统村落”和“文化景观”研究的双重价值，是中国乡村地理学探究的热点领域。通过定量与定性相结合的研究方法，以中国知网为基础数据库，深入剖析1990—2020年中国传统村落文化景观的研究内容及进展，评述前人研究成果并展望未来研究方向，以期为拓展传统村落文化景观研究维度提供重要参考。研究发现，近30年传统村落文化景观研究随时代的发展愈发细化，研究内容主要集中于传统村落文化景观特征与价值、形成与演化、保护与发展等3方面。但现有研究深度和广度还有待加强，传统村落文化景观多尺度研究还需深化、研究议题有待丰富、学科融合与方法集成仍需强化。今后应注重系统化的理论分析，拓宽传统村落文化景观的研究尺度；深化与拓展研究内容，挖掘传统村落文化景观的研究议题；强化学科融合与方法集成，完善传统村落文化景观的研究框架。