THE γ-FUNCTION PSEUDODYNAMIC ALGORITHM

Practical applications of the γ-function dissipative explicit method to pseudodynamic tests are thoroughly investigated herein. Detailed implementation of this pseudodynamic algorithm is schematically sketched. Numerical experiments and verification tests strongly indicate that the γ-function dissipative explicit method can effectively filter out the spurious participation of high frequency responses while the lower mode responses can be obtained very accurately. In addition, error propagation analysis also shows that the γ-function dissipative explicit method possesses much better error propagation characteristics when compared to the Newmark explicit method. Thus, this pseudodynamic algorithm is very suitable for the test system where the responses are dominated by the low frequency modes and the high frequency responses are of no interest.     

TECHNICAL NOTE A FRAMEWORK FOR MULTI-SITE DISTRIBUTED SIMULATION AND APPLICATION TO COMPLEX STRUCTURAL SYSTEMS

In this technical note, the development of a framework for multi-site distributed simulations is presented. The algorithm is suitable for any combination of physical (laboratory) and analytical (computer) distributed simulations of structures, their foundations and the underlying sub-strata subjected to static and dynamic loading. Two examples of multi-site testing and multi-platform simulation are given. The main contribution in this note is the separation between time-step integration and stiffness formulation, which enables the use of static analysis and testing as modules of the main control module referred to as the simulation coordinator. The approach proposed is intuitive, simple and efficient. It is therefore recommended for use in distributed analysis using different programs, distributed testing facilities (e.g. the NEES equipment sites) or a combination of analysis and testing.     

A Tale of Two Train Journeys: Lawrence Bragg,C. P. Snow and The ‘Two Cultures’

It was during two train-journey meetings with the physicist William Lawrence Bragg (1890–1971) that both Charles Percy Snow's (1905–1980) civil service career and, if the anecdotal evidence is to be believed, the ‘two cultures’ metaphor originated. The first part of this paper is concerned with the background, consequences and significance of the first of these journeys: Kettering station in 1939. It will address the somewhat hazy record of Snow's wartime work found in existing accounts, and argue that Snow's wartime experience helped shape his characterisation of the scientific side of his ‘two cultures’. The second part of this paper deals with Bragg's intellectual influence on Snow, tracing the former's interest in ‘two cultures’ arguments prior to probable encounters between the two on the Cambridge to London train in the late 1940s and early 1950s, including a historically hazy one in which together they allegedly coined the famous phrase. In examining their early relationship, it becomes clear that Bragg was a key influence and support in Snow's career as an administrator and as a cultural commentator.     

Polarized light microscopy casts new light on plants used to make tapa

Information about plant materials of construction in artefacts advances knowledge about human history, agriculture, trade, migration and adaptation to new environments. Typically, materials identification in artefacts made from plants is problematic, since processing, age, dirt and surface treatments can mask identifying features, while ethical considerations relating to sampling limit the use of some analytical techniques. The study tests the usefulness of polarized light microscopy for identifying the New Zealand and Pacific plant species used to make tapa, indicating birefringent and morphological characteristics that can be used to differentiate fibres at the level Moraceae (Pacific; from genera Artocarpus, Broussonetia and Ficus) and Malvaceae (New Zealand; from genera Hoheria and Plangianthus).     

单檐歇山式木构古建抵抗极端烈度地震试验调查研究

为更好地保护我国古建筑,基于《单檐歇山式古建筑抗震性能振动台试验》的相关成果,研究了强震作用下我国明清官式木构古建的抗震性能,制作了与该论文相同的试验模型,进行了振动台试验。通过对模型输入烈度逐渐增强的1940年El-centro波,并考虑地震波为水平双向作用,分析了强震作用下不同构造的试验现象,开展了详细的震后调查,获得了不同构造在强震作用下的抗震性能和震害机制。结果表明:强震作用下,我国明清官式木构古建的振动形式表现为柱架、斗拱、梁架及屋顶的近似同步往复摇摆;主要震害包括柱底偏移、榫卯节点开裂、拔榫、斗拱偏移及错位、额枋-垫板分离、墙体倒塌等,但承重木构架受损不严重,结构未产生倒塌。其良好抗震性能的原因与古建筑的构造特征密切相关。     

Breccia verde di Sparta,an elusive decorative stone used in antiquity

Breccia verde di Sparta is the traditional name given by the Roman marmorarii of the 19th century to a brecciated volcanic rock whose unknown precise provenance has been determined here for the first time through exploration of the broader area of Psefí (south of Krokees, province of Sparta, Peloponnese, Greece). This location was well known in antiquity and in modern times for having been exploited by the Romans for an important green porphyry named lapis lacedaemonius, nowadays also known as porfido verde antico. This breccia has been seldom used in Roman times for opera sectilia; in contrast, it appears more frequently reused in medieval floors; it is also frequently present in historical lithotecs formed in the 19th and 20th centuries. To fully characterise it and determine its relationships with green porphyry, breccia verde di Sparta samples from the newly discovered source have been thoroughly studied minero-petrographically and geochemically, and their complex genesis has been reconstructed. It appears that after extrusion the original brecciated basaltic andesite underwent extensive hydrothermal low-grade metamorphism, with a complete alteration of the igneous assemblage and minerals that preserved only part of the clinopyroxene phenocrysts. Alteration was accompanied by crystallisation of abundant epidote and chlorite, which imparted its predominant green colour to the rock. These breccias intruded in the lithoclases of the porphyry.     

贯入法原位测试夯土遗址表面强度的适用性和方法研究

表面强度是夯土遗址重要的测试指标和加固效果的评价依据。常规的强度测试方法受到取样和运输等因素的制约，不适用于作为夯土遗址如夯土补筑、表面加固等措施的效果评估方法。贯入法是成熟的砂浆强度检测方法，通过改装砂浆贯入仪降低了仪器量程；制作夯土样、室内试验验证了测试的较高精度；标定了夯土样贯入深度测量值与抗压强度的幂函数关系，确定了测强曲线。在夯土遗址现场开展原位测试，分析了布点密度对测试结果精度的影响，并利用测强曲线推算了测试区域的表面抗压强度。本研究提出了一套集“仪器改装-室内标定-现场高密度布点测试”为一体的夯土遗址表面强度评估方法，为土遗址加固效果的评价体系建设提供了参考价值。     

中俄双边旅游与进出口贸易互动关系的实证研究

以1998-2011年中俄两国旅游与贸易数据为基础,利用格兰杰因果关系检验发现俄国出境旅游是进出口贸易的单向格兰杰原因,中国进出口贸易是出境旅游的单向格兰杰原因。旅游与贸易互动关系研究结果表明:俄国出境旅游对进出口中国贸易均有着明显的推动作用,并对进口贸易的推动作用要明显强一些;中国进出口贸易对出境俄旅游都有明显的促进作用,进口贸易的促进作用要略强一点。俄罗斯断面看,占中国入境旅游比对对华贸易依存度有一定影响;中国断面看,中国对俄贸易依存度对出境俄旅游偏好和占俄入境旅游比影响均较大。两国旅游与贸易的互动性差异特征分析能为两国双边旅游与贸易良性互动发展提供相应参考。     

Natural‐gradient tracer experiments in epikarst: a test study in the Acqua dei Faggi experimental site,southern Italy

Two natural‐gradient tracer experiments were carried out using borehole fluorometers in order to characterize the internal structure of epikarstic horizons and analyze subsurface flow within these high‐conductivity layers. The experiments were carried out in a test site in southern Italy where the epikarst is made up of an upper part with pervasive karstification and a lower part without pervasive karstification. Injection and observation boreholes were 6.9 m apart. An initial experiment demonstrated that wider (conduits) and narrower (fractures and bedding planes) openings coexist in a well‐connected network within the lower epikarst. The adjusted aperture of the opening network (105 μm) suggests that conduits are subordinately developed. The lower epikarstic horizon is hydraulically similar to granular porous media and Darcy’s law can be applied to describe groundwater flow. A small value of longitudinal dispersivity (0.13 m) shows that variations in the velocity field in the direction of flow are less significant than those typical of carbonate systems at the same experiment scale. A second experiment demonstrated that longitudinal dispersivity (2.42 m) in the upper epikarst is in agreement with findings in other carbonates at the same experiment scale. However, despite the higher dispersivity and more pervasive karstification, the mean tracer velocity (3.7 m day^?1) in the upper epikarst is slightly lower than the velocity in the lower epikarst (13.6 m day^?1).     

自贡盐业铁工具的防锈保护

通过对馆藏盐业铁工具的锈层性状及结构的检测分析,并结合当地环境气候特征,认为其继续锈蚀的机制是电化学循环机制,提出除去有害锈、涂料封护的CLFJ防锈法。CLFJ防锈法处理生成的表面膜经防锈性检测,耐CuSO_4滴液、耐盐水性及耐水性指标全部合格,经模拟自然暴露3年条件下工业大气浸蚀的加速实验表明,馆藏条件下防锈时效性指标达5年以上;同时,表面膜呈现出贴近原貌的铁锈色。