Edge damage distribution at the assemblage level on Middle Stone Age lithics: an image-based GIS approach

Lithic artifacts represent the most abundant cultural remains from Middle Stone Age sites in southern Africa. Of these, pointed forms (under a variety of names), blades, and flakes have long been recognized as the three most abundant general types, and retouch on all three is rare relative to similar forms of equivalent age elsewhere. Here we offer a new technique for documenting concentrations of edge damage on an assemblage level to infer taphonomic processes and to record usewear and retouch. This approach is specifically aimed at patterning on the assemblage scale, rather than on individual artifacts. We use points from a Middle Stone Age assemblage from Pinnacle Point Cave 13B, near Mossel Bay, South Africa, to illustrate the technique. Combining GIS, rose diagrams, and polar statistics, we were able to visually and statistically summarize lithic artifacts for patterns of edge damage. For the points made on quartzite in this assemblage, edge damage was found to be significantly patterned and taphonomic causes of the damage were rejected. The technique also opens avenues for many other quantitative analyses that are either impossible or difficult with current non-visual systems of recording, such as measurements of distance, angle, and area of edge damage.     

重庆钓鱼城遗址悬空卧佛彩绘颜料初步分析

钓鱼城悬空卧佛造像系创作于晚唐时期的一尊巨型石刻,具有极高的历史、艺术、科学、宗教价值,但造像保存现状较差,存在颜料脱落、酥碱粉化、起甲等病害,亟待保护修复。为了解悬空卧佛彩绘颜料层的成分与结构,采用金相显微镜、拉曼光谱、X射线荧光(XRF)、X射线衍射(XRD)、扫描电镜-能谱仪(SEM-EDS)等多种现代方法与技术对彩绘样品进行了分析。结果表明:所用红色颜料为铁红、铅丹;蓝色颜料为群青;绿色颜料为碱式氯化铜;青色颜料为墨绿砷铜矿;白色颜料为硫酸铅;局部有贴金。结果还表明,该造像历史上曾多次重绘。本研究成果以期填补钓鱼城悬空卧佛研究的空白,同时为修复工作的开展提供科学依据。     

A Probability-based Approach for the Definition of the Expected Seismic Damage Evaluated with Non-linear Time-History Analyses

The seismic damage evaluated through Nonlinear Time-History Analyses is significantly affected by the response quantity chosen to represent the seismic responses. Starting from the theory of tolerance regions, a generic upper limit of the seismic responses is proposed. The method is applied to a reinforced concrete structure subjected to different record combinations. For each considered damage index and record combination, the upper limit damage is compared with the average value suggested by seismic codes. The proposed method yields a higher seismic damage than the average response and an increase in the damage indices as the number of records decreases.     

Some Discussions on Data-Driven Testing of Ground-Motion Prediction Equations under the Turkish Ground-Motion Database

Data-driven testing of ground-motion prediction equations (GMPEs) can help researchers in the ranking and selection of GMPEs for seismic hazard assessment. This paper presents and discusses the details of the major features of well-known testing methods which employ likelihood and Euclidean distance concepts. A set of local, regional, and global GMPEs are assessed under a ground-motion database. The data-driven testing of GMPEs is supported by thorough residual analyses under the database, providing valuable insights into the testing of GMPEs. The researchers are advised to evaluate all options together instead of focusing on a specific tool to build well-structured ground-motion logic trees.     

A Single-Run Dynamic-Based Approach for Pushover Analysis of Structures Subjected to Near-Fault Pulse-Like Ground Motions

In this paper, a fairly effective procedure called dynamic load pattern (DLP), is proposed to account for the effects of near-fault ground motions in estimating the seismic demands of structures from pushover analyses. The seismic demands are obtained by enveloping the results of single-run conventional first-mode and single-run DLP pushover analyses. Improving the estimation of target displacement is another objective, implemented by performing response-spectrum analysis. Three special steel moment-resisting frames are considered and the seismic demands resulting from DLP are compared to those from the nonlinear time-history analysis as a benchmark solution, as well as to those predicted from modal pushover analysis.     

农业生态区的数值划分——以桂西南为例

农业生态区划是土地承载力研究的重要内容,生态区划的数值分类,可避免传统方法主观性和任意性的弱点,桂西南山区16县(市)在系统聚类分析基础上划分为三个农业生态区:左江及右江下游河谷区,右江上游河谷区和靖西山原区。     

大气环境对岭南传统灰塑装饰的危害及相应的保护研究——以广州陈氏书院灰塑为例

本文以全国重点文物保护单位广州陈氏书院内的灰塑装饰为研究对象,针对灰塑的物理化学性质和主要损坏情况,结合广州地区大气环境常年变化情况,分析了大气环境对灰塑装饰的危害,拟定了岭南地区古建筑灰塑装饰保护的全年性和季节性保护措施,在一定程度上填补了岭南地区灰塑艺术在保养和维护方面的空白。     

Seismic Vulnerability Analysis of RC Bridges Based on Kriging Model

This paper presents a Kriging model-based method for seismic vulnerability analysis of reinforced concrete (RC) bridges. It aims at reducing the computational effect when the Monte Carlo technique is used for establishing the structural vulnerability curves. The general procedure of the proposed method is put forward firstly. In the procedure, the uncertainties existing in the structures and ground motions are both taken into account, and the uniform design (UD) technique is adopted for generating the random samples. The reliability of the proposed method is demonstrated by the vulnerability analysis of an single degree of freedom (SDOF) system using the Latin hypercube simulation (LHS) method. Vulnerability analysis of an RC bridge system is then carried out using the proposed method. The vulnerability curves of the bridge obtained by the Kriging model-based method are compared with those obtained by the LHS method. Additionally, three simulation schemes adopting different UD tables are employed to investigate the convergence and stability of the proposed method. The results show that the proposed method used for the seismic vulnerability analysis of RC bridges can reduce the computational effort and time to a large extent without much compromise on the accuracy.     

陕西历史博物馆藏汉代“华仓”瓦当表面析出物的分析研究

陶质文物表面析出物中含有机酸盐的现象在国内鲜有报道。本研究采用离子色谱仪(IC)、扫描电子显微镜-能谱仪(SEM-EDS)、X射线衍射仪(XRD)、傅里叶变化显微红外光谱仪(FTIR)、超景深显微镜(DM)对一件馆藏汉代“华仓”瓦当表面析出物进行了表征和检测。结果表明,瓦当表面析出物主要由少量的二水硫酸钙和大量有机酸钙盐[Ca₃(CH₃COO)₃Cl(NO₃)₂·6H₂O]组成,两种盐的形成与瓦当的制作过程、埋藏环境和灰尘有关,有机酸盐的形成还与馆藏环境中的乙酸有关。这种析出物不仅影响瓦当表面的真实文物信息,还会进一步腐蚀瓦当本体,建议从展柜中取出瓦当进行脱盐处理,存放在无酸的环境中。本检测分析为这件瓦当的保护修复方案的制定提供理论依据,也为类似文物样品的分析提供借鉴。     

中国主要城市旅游效率的区域差异与空间格局

追求更高的资源利用效率是城市旅游发展的目标。利用数据包络分析方法,对2005年58个中国主要城市的旅游效率进行了评价。结果显示:东部地区城市的旅游效率水平明显高于中部、西部和东北地区;分解效率中,规模效率的差距较大,而技术效率和利用效率的差距则较小,高效率城市主要集中在大城市和沿海经济发达地区;规模效率是影响总效率的直接原因,而区域经济发展的不平衡性是导致不同城市资源投入水平差异,并最终导致规模效率空间差异和总效率空间差异的根本原因。文章最后讨论了提高不同地理空间上城市旅游效率的建议。