从张四墩遗址看薛家岗文化的去向

采用ICP等离子体发射光谱方法,测试分析了安徽张四墩遗址和薛家岗遗址出土陶器的微量元素,并运用热膨胀法测定了低温古陶器的烧成温度。在此基础上,结合考古发掘资料,将测试数据作多元统计分析,系统讨论了张四墩遗址不同文化风格古陶的矿料来源,并探讨了张四墩遗址与薛家岗遗址陶器的产地、渊源的关系和制陶工艺方面烧成温度的变化关系,研究结果表明:张四墩遗址反映的文化是一种多元性的文化。一方面,它承继了本地薛家岗文化的部分因素,另一方面,受到东部的良渚文化,特别是北方大汶口文化的强烈影响。     

Thermodynamic study of capillary pressure curves based on free energy minimization

This paper presents a new method for pore level network simulation of the distribution of two immiscible phases in a permeable medium. The method requires that the Helmholtz free energy of the system — the medium and the two phases contained within the pore space — be a minimum at all saturation states. We describe the method here and show some typical results from a computer algorithm that implements it. The results include (i) an explanation of the ‘scanning’ behaviour of capillary pressure curves based wholly on the free energy minimization, (ii) predictions of capillary pressure at arbitrary wetting states, including negative capillary pressures, and (iii) illustrations of how the minimized free energy changes along the scanning curves. The method also predicts the known dependency of the capillary pressure on the pore size distribution and interfacial tension. The current work is restricted to two‐dimensional networks, but the free energy minimization appears to be generalizable to three dimensions and to more than two fluid phases. Moreover, functions generated through the minimization, specifically contact areas between the medium surface and the phases, appear to have applications predicting other multiphase petrophysical properties.     

Numerical models of petroleum migration via buoyancy-driven porosity waves in viscously deformable sediments

The apparent ability of petroleum to migrate rapidly through low permeability sediments in sedimentary basins has led to many questions about the manner of its transport. One possible explanation is suggested from observations of the compaction of viscously deformable porous media. These systems have been found in some cases to give rise to regions of locally elevated liquid fraction, in the form of fluid‐filled porosity waves that can ascend at rates much greater than that of the background flow. Previous research on the phenomenon has focused on its implications for magma transport, but recognition of the fact that the compaction of viscous porous media can take place in sedimentary basins has suggested the possibility that porosity waves could similarly be important for hydrocarbon transport. The purpose of the present study was to test this hypothesis by quantifying the transport that would occur as the result of porosity waves initiated during the conversion of kerogen to petroleum. A one‐dimensional numerical model was constructed solving equations for the mechanics of viscous compaction and for the kinetics of reactions describing the formation of petroleum from kerogen. The results showed that porosity waves would develop readily in viscously deformable regions of sedimentary basins, but would not necessarily provide enhanced transport over that of the background flow regime. In order for the waves to achieve this enhanced transport, they must develop high amplitudes, i.e. high porosities relative to the background porous medium. To achieve the high wave amplitudes, the background porosity must be very low in absolute terms. In addition, high kerogen contents are needed in the source layer, and the source layer needs to be buried rapidly to a high temperature region of the oil window. Considerable uncertainty exists as to the value of the matrix shear viscosity of sediments in basins. However, the wave volumetric transport capacity was not found to be significantly altered as a result of variations in the value of this parameter. The physical form of the waves was strongly altered by the matrix shear viscosity, with higher values leading to lower amplitudes and generation frequency, but higher wavelengths. Thus the waves become less recognizable physically at higher values of the matrix shear viscosity. As the waves ascend to higher stratigraphic levels, where the porosity is higher, they gradually lose their physical definition and become absorbed into the background.     

Models of settlement hierarchy based on partial evidence

The modelling of past settlement and landscape structure from incomplete evidence is a well-established archaeological agenda. This paper highlights a model of spatial interaction and settlement evolution that has long been popular in urban geography and which was first applied to model historical settlement hierarchies some twenty-five years ago, but whose use since then for archaeological purposes has been very limited. Via a case study from Bronze Age Crete, we extend the analytical range of this model by suggesting ways in which it can (a) remain effective in the presence of missing data, (b) be given a stronger grounding in the physical landscape, and/or (c) be used to consider the evolutionary trajectory of settlements and physical routes over time.     

公共危机治理主体的多元化及结构分析

政府失败理论、治理理论、利益相关者理论和协同理论为公共危机治理主体多元化提供了强有力的理论支撑。在多元主体结构中,政府是公共危机治理的主导力量,也是核心主体;民间组织是公共危机治理的重要力量,也是联系政府与公民的纽带;企业和公民是公共危机治理的基础;媒体是公共危机治理的重要媒介,也是政府与其他主体合作互助信息平台的主要搭建者。     

中国旅游业资本流动与生产率演化——基于DSSA方法的结构效应分析

在中国旅游业转型升级的重要时期,开展全国及31个省份旅游产业结构变动与生产率演化的研究具有显著的理论与现实意义。鉴于结构变动是影响生产率增长的一个重要因素,本文运用DSSA方法对全国及31个省份2000年—2016年旅游业资本生产率增长率进行分解,测度产业结构变动的生产率增长效应。结果发现,不同地区或省份之间表现出较大差异。在年度静态结构效应上,东部地区开放型旅游经济较为发达,各省份总体发展态势较为稳定,伴有阶段性波动;中部地区旅游经济相对闭塞,各省份总体发展的平稳性最差,波动性介于东部地区与西部地区之间;西部地区在大开发背景下旅游经济增长较快,各省份总体发展的平稳性介于东部地区与中部地区之间,波动性最大。在年度动态结构效应上,全国大部分省份在大部分年份都出现“结构负利”,动态结构能力亟须改善。尽管各省份表现出差异化的静态结构能力和动态结构能力,但是我国整体旅游产业结构升级与旅游经济增长的发展态势相耦合。本文的结构效应分析结果可为东部、中部和西部地区及不同省份旅游业转型升级提供理论依据和决策参考。     

Cyclical downturn or structural disease? The decline of the Italian economy in the last twenty years

Italy is experiencing at present the most serious economic recession of the post-war period. Between 2008 and 2013 national income fell by 9 per cent, per capita incomes by 11 per cent, and industrial production by 25 per cent; and unemployment doubled. In this essay we argue that, while this dramatic situation has been made worse by the policies of ‘expansive austerity’, its origins can be traced back to changes that took place in the 1990s (notably globalization, competition for emerging new markets and the diffusion of new technologies – ICT) to which Italy failed to react speedily or effectively by reorganizing its entire productive system. Instead, many of the reforms that have been introduced with respect to the labour market, for example, have reduced costs but in ways that have encouraged firms to stay in traditional sectors where products are poorly differentiated and of low technology content. If the Italian economy is not to become even weaker, new reforms are urgently needed to encourage innovative investment and push through to completion a restructuring of the industrial system that can no longer be deferred.