试析尼克松政府对外政策决策机制、过程及主要人员

现已出版的关于尼克松政府的著作,大多试图破译尼克松和基辛格这两位历史人物的思维方式以及他们的个性缺陷。根据新解密的尼克松总统档案和现已发表的英文研究成果,通过研究尼克松政府对外政策决策新机制的确立及其特点,透视尼克松政府对外政策决策机制、过程及涉及的主要人员相关特点,能够加强人们对尼克松政府对外政策决策的认识和理解。从理论上讲,尼克松政府的对外政策决策机制,目的是保证总统的工作日程和时间;总统得到的是经过认真研究、分析和过滤后的情报信息。尼克松任内,确实取得了外交方面的重大成功。然而,这一机制是将美国对外政策决策的千斤重担压到了尼克松和基辛格两人的肩上,违背了美国政府决策民主程序的理念。     

Nonlinear Structural Performance of a Historical Brick Masonry Inverted Dome

ABSTRACT

Traditional domes are obtained by double curvature shells, which can be rotationally formed by any curved geometrical plane figure rotating about a central vertical axis. They are self-supported and stabilized by the force of gravity acting on their weight to hold them in compression. However, the behavior of inverted domes is different since the dome is downward and masonry inverted domes and their structural behaviors in the literature received limited attention. This article presents a nonlinear finite element analysis of historical brick masonry inverted domes under static and seismic loads. The brick masonry inverted dome in the tomb of scholar Ahmed-El Cezeri, town of Cizre, Turkey, constructed in 1508 is selected as an application. First, a detailed literature review on the masonry domes is given and the selected inverted dome is described briefly. 3D solid and continuum finite element models of the inverted masonry dome are obtained from the surveys. An isotropic Concrete Damage Plasticity (CDP) material model adjusted to masonry structures with the same tensile strength assumed along the parallel and meridian directions of the inverted dome is considered. The nonlinear static analyses and a parametric study by changing the mechanical properties of the brick unit of the inverted masonry dome are performed under gravity loads. The acceleration records of vertical and horizontal components of May 1, 2003 Bingöl earthquake (Mw = 6.4), Turkey, occurred near the region, are chosen for the nonlinear seismic analyses. Nonlinear step by step seismic analyses of the inverted dome are implemented under the vertical and horizontal components of the earthquake, separately. Static modal and seismic responses of the inverted masonry dome are evaluated using mode shapes, minimum and maximum principal strains and stresses, and damage propagations.     

近代英国工业城市的空间结构与城市规划（1848-1939）

以曼彻斯特、伯明翰和利兹为代表的新型工业城市在空间结构方面体现出鲜明特征:随着新型工业建筑的出现,土地功能实现区分;各类建筑交叉林立,城市布局混乱;新的社会阶层居所分离形成。这种空间结构特征,使得工业城市中的"城市病"问题尤为突出。在英国19世纪中叶兴起的近代城市规划运动中,工业城市积极开展规划实践,空间结构得到合理重组,"城市病"得以缓解,城市面貌显著改观。     

Reaction to Fire of Existing Timber Elements Protected With Fire Retardant Treatments: Experimental Assessment

Fire safety is an important issue of building safety, especially when the building’s fire load contents enhance the risks of fire deflagration. When existing timber structures are involved, the most usual way to improve its reaction to fire is to treat wood with fire retardants. This study focuses on the surface protection of existing timber roof structures against fire, through the use of fire retardant (FR) treatments applied on site. An experimental investigation was carried out to study the effect of FR treatments on timber reaction to fire, with a special emphasis on timber members with biological deterioration and previously treated with preservative products. The behaviour and effectiveness of intumescent and non-intumescent treatments was also investigated. The study showed that the application of FR treatments improved the reaction to fire of timber, even in the presence of previous preservative treatments. However, the choice of the specific FR treatment should take into account the substrate conditions. In addition, test results suggest that protection systems involving multi layers (intumescent and non-intumescent) with different functioning modes each are likely to have a good global performance on the protection of timber elements against fire.     

Crack Patterns Induced by Foundation Settlements: Integrated Analysis on a Renaissance Masonry Palace in Italy

This study presents some numerical results related to the analysis of the structural damage of a historic masonry building, Palazzo Gulinelli, in Ferrara, Italy. A detailed analysis of the inhomogeneities of the facade, historic documentation, and recent restoration interventions carried out in an adjacent building, suggest that the Palace underwent various modifications both on the structural configuration and on the borne loads. Such modifications might be the main cause of some differential settlements and of the consequent significant crack pattern on the load-bearing walls. Therefore, in the present paper the occurrence of a crack pattern on the facade is simulated by carrying out standard linear and non-linear finite element (FE) homogenized models; differential settlements are applied in order to reproduce the structural changes occurred over time. Previous experiences of the authors (for example, Acito and Milani in 2012 and Mallardo et al. in 2008), the current crack pattern of the building (of its facade in particular) and the monitoring data referring to some of them are the main references for the analysis carried out. The structural survey, the numerical results, and the data monitoring suggest two main conclusions: 1) a good correlation between numerical results and monitoring data is assessed, therefore the cracks can be reasonably related to past differential settlements; and 2) the cracks/damage that occurred as a consequence of differential foundation settlements reduce the ability of the facade to resist seismic actions.     

A Pre-Lapita Structure at Apalo,Arawe Islands,Papua New Guinea

Stilt structures in the inter-tidal zone or over shallow water on fringing reefs are widely accepted as a feature of settlements of the Lapita cultural complex in Near Oceania. Claims for similar structures in a pre-Lapita context at the Apalo site in the Arawe Islands, New Britain, Papua New Guinea, have been queried on several grounds. Re-evaluation of the Apalo evidence, together with 10 additional AMS radiocarbon dates, establishes human activity associated with some form of structure and possibly with a ground stone axe about 400–500 years before the Lapita pottery occupation. The paucity of occupational refuse suggests a non-residential structure perhaps associated with water transport. Comparisons with the older Dongan midden site in the Sepik-Ramu basin suggest stilt structures were probably used there as well. An apparent shift in depositional processes between the pre-Lapita and Lapita use of Apalo could reflect changed sea conditions arising from increased ENSO activity.     

旅游业循环经济:发展观、伦理观与产业范式

分析旅游业实施循环经济的理论与时代背景。将我国传统旅游经济归纳为资源中心发展观、产品中心发展观和顾客中心发展观等传统范式阶段,并主张以循环生态发展观来扬弃传统的人类中心型的发展方式。从环境观、资源观、社会观、科技观等层次对旅游业循环经济的伦理观进行了阐述。提出旅游业循环经济包括单体企业层次、企业群落层次、旅游业产业群落层次和国民经济的大生产群落层次等四个结构层次,总结了旅游六要素的循环经济运作观。最后,对比分析了传统旅游经济与循环型旅游经济的范式结构,提出旅游循环经济的实现还存在技术、观念和利益机制的障碍。     

The global city thesis — social polarization and changes in the distribution of wages

The global city thesis by which Sassen (1991) has linked globalization with increased social polarization has attracted much attention and caused considerable discussion over the past decade. This article illustrates divergent approaches that have been taken to the study of social polarization and provides an overview of the issues that have been discussed in relation to the polarization debate. I argue that the global city thesis has been misleading and that the empirical work underlying it has been too limited. Thereafter I test the empirical basis for Sassen's thesis in an analysis of the distribution of wages in the New York Metropolitan Area during the period 1970 to 1990.     

Tracing firing technology through clay properties in Cuzco,Peru

The purpose of this study was to identify changes in firing practices that occurred during a timeframe that saw the introduction of European kiln technology to the Andes (AD 900–1800). Pottery from an excavated context at the archaeological site of Aqnapampa in the southern highlands of Peru was examined for changes in paste recipes that adapted local materials to increased firing temperatures indicative of evolving firing technologies. Sherds (60) and fragments refired to 890 °C from 12 stratigraphic levels were compared by style, surface treatment, paste color, and vitrification structures (ESEM). Four technological phases of the Cuzco pottery sequence emerged and were used to evaluate the trajectory of a single decorative style (Killke). Previously thought to have been produced in pre-Inca times and curated into later periods, the Killke sherds presented evidence that the style was produced using technologies introduced in the Inca and Spanish Colonial Period.     

Water,Wind, Wood,and Trees: Interactions,Spatial Variations,Temporal Dynamics,and their Potential Role in River Rehabilitation

Recent Australian research has quantified the role of large wood (wood of any origin and length with a diameter greater than 0.1 m) in dissipating stream energy, forming pool habitats by local bed scour, protecting river banks from erosion, and damming rivers with long rafts causing avulsions. Large wood in Australian streams is sourced by a range of processes from the nearby riparian zone which has usually been degraded by post‐European settlement vegetation clearing. Large wood loadings within the bankfull channel are dependent not only on the type and quality of the riparian plant community but also on bankfull specific stream power, channel width, and the processes of large wood delivery to the stream. While bank erosion and floodplain stripping by catastrophic floods are obvious and important delivery mechanisms, treefall and trunk and branch breakage by strong winds during tropical cyclones and severe storms are also significant in the tropics. Furthermore, wood decay and downstream transport produce temporally dynamic large wood distributions. The longevity of natural large wood structures in rivers, such as rafts, debris dams, and log steps, requires determination. River rehabilitation programs need to not only include the reintroduction of large wood, but also carefully plan the spatial distribution of that wood, the most appropriate type and range of large wood structures, and, most importantly, the revegetation of the riparian zone to ensure a natural long‐term source of large wood. Exotic species management is an essential part of river rehabilitation.