Ground‐Penetrating Radar Velocity Determination and Precision Estimates Using Common‐Midpoint (CMP) Collection with Hand‐Picking,Semblance Analysis and Cross‐Correlation Analysis: A Case Study and Tutorial for Archaeologists

The most crucial parameter to be determined in an archaeological ground‐penetrating radar (GPR) survey is the velocity of the subsurface material. Precision velocity estimates comprise the basis for depth estimation, topographic correction and migration, and can therefore be the difference between spurious interpretations and/or efficient GPR‐guided excavation with sound archaeological interpretation of the GPR results. Here, we examine the options available for determining the GPR velocity and for assessing the precision of velocity estimates from GPR data, using data collected at a small‐scale iron‐working site in Rhode Island, United States. In the case study, the initial velocity analysis of common‐offset GPR profile data, using the popular method of hyperbola fitting, produced some unexpectedly high subsurface signal velocity estimates, while analysis of common midpoint (CMP) GPR data yielded a more reasonable subsurface signal velocity estimate. Several reflection analysis procedures for CMP data, including hand and automated signal picking using cross‐correlation and semblance analysis, are used and discussed here in terms of efficiency of processing and yielded results. The case study demonstrates that CMP data may offer more accurate and precise velocity estimates than hyperbola fitting under certain field conditions, and that semblance analysis, though faster than hand‐picking or cross‐correlation, offers less precision.     

郑州商文化陶字符量化分析

对郑州商文化陶字符量化分析结果显示,早商文化陶字符使用以具有首都地位的郑州早商文化遗址最为集中,具有较强的地域性。郑州早商文化陶字符分期演进中出现一些分界现象,缘于商文化的兴盛和文化中心的转移。郑州商文化陶字符多出现于祭祀场所和手工业作坊遗址具有特殊意义的遗迹,表明其主要为生活、手工业生产、祭祀活动中有关数量、日期、位序、族属、地点等信息的记录遗存。     

舞阳贾湖墓葬的统计学初步分析

本工作旨在了解贾湖单人墓随葬品数量与墓主人性别、年龄以及墓葬分期之间的关系。根据墓葬样本的实际情况,本工作使用t-检验、单因素和双因素方差分析的方法进行了初步的统计学分析。结果显示,贾湖墓葬随葬品总量与性别无关,但与墓主人的死亡年龄有关,壮年随葬品较丰富。同时,随葬品数量受到性别和死亡年龄的交互影响比较显著,女性少年儿童的随葬品数量最多,男性壮年的随葬品次之。从随葬品的种类上看,除少年儿童组最多外,女性壮年墓葬占有石制品最多;男性壮年墓葬占有骨、牙制品最多。本工作还发现陶器和骨、牙制品的数量在不同时期存在着较显著变化,第二期时骨、牙制品和陶制品的数量较多。本工作认为,女孩随葬品数量较多的情况可能与母系氏族社会重女习俗有关,不同性别的壮年侧重随葬不同质地的物品则可能暗示着贾湖先民们已经出现了一定程度的社会分工,陶和骨、牙制品在第二期时比较丰富的现象可能与这一时期渔猎采集活动较活跃有关。     

“华光礁一号”南宋沉船船板中硫铁化合物分析

鉴于硫铁化合物对海洋出水木质文物的特殊危害,通过 X射线衍射(XRD)、等离子体发射光谱(ICP-AES)和 X射线光电子能谱(XPS)等分析手段,对“华光礁一号”南宋沉船船板残块中的硫铁化合物进行了分析研究。结果表明,所采集的样品中含有大量的 Fe和 S元素,并且其分布深度至少可达 4cm。两种元素的化学状态基本可分为铁的氧化物、硫铁化合物、硫酸盐和其它还原性硫四大类。其中,硫铁化合物主要以 FeS和 FeS₂形式存在,并已部分氧化成硫酸盐。因此,在后续的保护处理过程需着重对其酸化过程进行控制,以有利于文物的长期保存。     

The oldest evidence of painted furniture from Sweden – The 12th century chair from Suntak

The 12th century Suntak chair is one of the earliest pieces of furniture known from Sweden. A close examination revealed minute remnants of possible colour pigments on several parts of the chair. Chemical analyses of the pigments revealed the presence of several colours such as black, white and red. This paper attempts to shed light upon the identification and origin of the pigments as well as the time of painting. The original use and the setting of the chair will also be discussed.     

Late medieval copper alloying practices: a view from a Parisian workshop of the 14th century AD

161 late medieval copper-based day-to-day items have been analysed, mostly consisting of small artefacts such as dress fittings. The items were all recently excavated from a 14th century AD metallurgical workshop located in Paris. Eight well-defined copper alloys have been identified that refer to various constraints, the most important one being economics. According to the model proposed, most of the alloys were obtained by dilution of a fresh brass master alloy by scrap metal containing small amounts of zinc, tin and lead. Pure lead was added separately in relatively large quantities, with a limit of 6 wt% Pb marking the boundary between leaded and unleaded alloys. It has been found that the less the cost of the artefact, the more the fresh brass is diluted. For the medium-size castings such as cast vessels, alloys containing large quantities of lead or alloys rich in antimony were used. Such complex alloying strategy pertains more to a small industrial-like plant organisation rather than to craftsman activity, as further supported by a variety of archaeological and historical evidence.     

Inelastic Demand Spectra of Bi-Linear Models for Capacity Spectrum Method and Response of Simple Structures under Near-Source Records

A very useful tool for the preliminary design of structures is the elastic demand spectrum that can be used in the capacity spectrum method. A pseudo-acceleration relationship has to be assumed when constructing a demand spectrum. This assumption results in large errors for long period structures with large damping ratios and the conventional demand spectra require a substitute elastic structure. In the present study, the conventional demand spectra are extended to bi-linear models. Pseudo-acceleration is still assumed but results in acceptably small errors, when a constant viscous damping coefficient for a single-degree-of-freedom (SDF) structure is calculated from the tangent stiffness and the damping ratio is set at 5% in both elastic and yield phases. For nonlinear structures, tangent stiffness dependency of damping force could be acceptable because energy absorption is primarily the result of structural nonlinear deformation. To extend the conventional demand spectra to a bi-linear model, effective period calculated from the secant stiffness has to be used. The use of effective period introduces no approximation because the peak displacement of the SDF structure is computed from nonlinear analysis in the time domain. The method presented in this study is also valid if damping coefficient proportional to initial elastic spectra is used. In this case, the pseudo-acceleration is defined as the base shear coefficient that is required to produce the peak displacement of the SDF structure in a static manner. We present demand spectra of bi-linear models for a number of near-source records from large earthquakes, and spectral ratios of two horizontal components. The effects of different types of ground motion on the response reduction factor due to inelastic deformation are investigated.     

Lightly Reinforced Walls Subjected to Seismic Excitations: Interpretation of CAMUS 2000–1 and 2000–2 Dynamic Tests

In this article a study is presented of the inelastic seismic performance of two 5-story reinforced concrete wall specimens, which were tested in the context of the CAMUS 2000 program. The structure has been sized and detailed following the French PS92 code. To investigate the simplifying assumptions made in design, a 3-D refined nonlinear analysis was conducted. Particular aspects of the behavior of the two tested specimens are presented and then test results are compared with numerical predictions. The experimental-analytical comparisons not only demonstrate the accuracy of the time-history analysis model, but also allow obtaining more detailed information about the behavior of the specimen when it is subjected to seismic excitation. The significant effect of degradation of the stiffness and strength of the wall suggests that it is always important that design procedures are derived from numerical modeling and experimental observations.     

Seismic Response of Secondary Systems Supported by Torsionally Yielding Structures

Substantial damage sustained during several recent earthquakes was non structural in nature. The economic consequence in terms of non structural component damage far exceeded the structural damage. Currently, there are several analytical studies that address the interaction between non structural components or Secondary systems (S-systems) and the main supporting structure or Primary system (P-system). Only a few of these analytical approaches have been proposed to evaluate and characterize the response of the S-systems attached to torsionally coupled P-systems. In addition, the experimental verification for the analytical approaches is scarce.

In the current study, the results and observations of an experimental research program conducted to characterize the behavior of both stiffness eccentric and mass eccentric torsionally coupled Primary-Secondary systems (PS-systems) are presented. From this experimental investigation it was found that the torsional yielding of the primary system has significant implications on the deamplification of near tuned secondary system response. The location of the S-system mounted on the P-system affects the peak response amplification, and interaction with the coupled P-system.