SIMPLE EXPRESSION OF THE DYNAMIC STIFFNESS OF GROUPED PILES IN SWAY MOTION

A simplified expression is derived for the dynamic stiffness of grouped piles subjected to lateral loading. A computer program, based on the Thin Layered Element Method, is used for this purpose. The results of the program are compared with rigorous solutions. The simplified expression of the dynamic stiffness of grouped piles, where the mass, damping and stiffness parameters are frequency invariant, will be particularly useful for an equivalent linear analysis of the interaction between nonlinear soil and grouped piles in real time.     

SHAKING TABLE DYNAMICS: RESULTS FROM A TEST-ANALYSIS COMPARISON STUDY

This paper presents the results of a comprehensive comparison study between the analytically predicted and experimentally identified dynamics of the shaking table system built recently in the Structural Engineering Laboratory at Rice University in Houston, Texas. The primary objectives of the research presented here are two-fold: (1) to shed light into the dynamic performance of asmall-tc-medium size, uni-axial, servo-hydraulic, displacement-controlled shaking table system, and (2) to validate a linearised dynamic model of the system (in the form of the total shaking table transfer function) developed earlier by the authors from basic principles. The analytical model incorporates the inherent dynamic characteristics of the various components of the shaking table system (i.e. controller, servovalve, actuator, test specimen, and reaction mass) and their dynamic interaction.

The test-analysis correlation study performed over a wide range of operating and payload conditions provides useful information on the sensitivity of the shaking table transfer function to control gain parameters and how it can be used to tune the shaking table controller for optimum performance under various payload conditions. The good test-analysis correlation results obtained validate the analytical shaking table model, show its robustness, and provide keen insight into the underlying coupled dynamics of a shaking table system. In order to achieve this good test-analysis correlation, it was crucial to include a time delay in the analytical model of the shaking table system (innovative feature of the model to account for the time lag in the response of the servovalve-actuator system). The expected significant dynamic interaction between payload and shaking table is also confirmed by this study.     

泛珠三角中心城市互动的动力、模式及合作领域分析

中心城市之间的互动,可以有力促进泛珠三角区域合作与发展,符合城市发展的内在需求和区域合作与发展的潮流,同时也符合中心城市与区域合作的发展历程。泛珠三角中心城市互动的重要动力是政府推动、市场机制、资源共享以及区域发展的差异性、互补性。有效的互动模式包括政府和企业双主体互动、产业对接、城市圈互动、友城战略等。泛珠三角中心城市互动可以在规划、加工制造业的分工与合作、口岸合作和大通关平台建设、社会资源等重点领域展开。     

Trepanation in the Chachapoya region of northern Perú

This paper discusses trepanation frequency data from the Chachapoya region of the northern highlands of Perú. New data from three skeletal samples are presented: Kuelap, Laguna Huayabamba, and Los Pinchudos, as well as isolated crania housed at the Chachapoya Museo Instituto Nacional de Cultura. The vast majority of the trepanations are circular in shape, except for one individual exhibiting as many as three roughly square trepanations. Evidence for healing is prevalent, with examples of both associated periosteal reaction of nearby outer table bone, as well as for healing of the insult itself. Only one case demonstrates a clear association between a traumatic injury and a trepanation event. The purpose or function of the remaining cases of trepanation, however, remains elusive. Copyright © 2006 John Wiley & Sons, Ltd.     

近代旅美华侨华人与中美文化的双向交流

鸦片战争强制性地拉开了中西文化交流的序幕。1848年以后,随着北美至中国航线的开通,一部分居住在珠江三角洲的广东人在多种原因的驱使下,远渡重洋来到北美。在美国西部形成了一个又一个的华侨华人社区,使中国的古老文明渐次播散到美国西部各州。随着北美华侨华人的不断扩展,不同类型的华侨华人在不同的领域里(商业、建筑、科技教育、宗教伦理、风俗习惯等许多文化领域里)对中华传统文化进行了被动和主动传播。被动的传播形成了美国多元文化的文化飞地,主动的传播使中国传统文化在美国文化的大熔炉里形成了一种鲜明的、交叉式的边缘文化。文化的传播是一个双向互动的过程。随着大批旅美华侨华人陆续返回故乡,他们也把西方文明带回侨乡。它们与本土文化发生碰撞、冲突、融合,从而在珠江三角洲一带的侨乡形成了新鲜的、西方式的边缘文化。     

郑国青铜礼乐器祭祀坑相关问题讨论

新郑祭祀遗址出土青铜礼乐器作为祭祀重器,是春秋中期郑国特殊祭祀文化的具体表现.不同遗址出土器物组合的差异,从器物层面体现了当时郑国高等级贵族间的微妙关系,轮流执政的卿大夫已经掌控了包括土地所有权在内的多项国家权力,拥有和国君同等级的礼器、乐器使用权,仅在用鼎数量方面存在着差异.作为祭器的祭祀坑出土青铜礼乐器和同时期墓葬出土器物有着本质上的区别,表明当时祭祀礼仪仍然严格遵循着传统礼制,也正是由于这个原因,不能将遗址出土青铜乐器与"郑卫之声"简单地等同分析.     

西周初期墓葬铜礼器器用区位研究——以随州叶家山为中心

随葬礼器在墓中的区位特征对于判断随葬品的性质与用途,探求墓葬器用观念等都具有重要意义。随州叶家山、宝鸡石鼓山墓地可分别作为西周初期诸侯国与王畿地区随葬青铜礼器组合的特点的代表。结合过去发现的同时期墓葬资料可以发现早在西周初期周人已建立起一套较完备的以食器为中心的器用组合关系。就其在墓葬中的区位而言,存在着(1)按大类分置;(2)食、酒水器分置;(3)酒水器聚置,食器分置于酒、水器两端等三种情形,前两种体现出周人重食的文化特征,后一种强调酒器似与周初西迁的殷遗民有关。     

Displacement Ductility Limits for Pile Foundations in Cohesionless Soils

The displacement ductility limit for seismic design of concrete piles is determined for the range of cohesionless soils expected in practice. The curvature ductility capacity associated with specified performance limit states, namely, the “serviceability” and “damage-control” limits, is determined based on the current provisions for confining steel. An analytical model is applied to assess the displacement ductility factor at the specified curvature ductility level. The investigated parameters include the soil stiffness, pile diameter, longitudinal reinforcement ratio, axial force level, and pile above-ground height. A set of design displacement ductility factors is recommended and verified to ensure the satisfactory seismic performance.     

Ritual Mutilation of Europeans on the Torres Strait Maritime Frontier

Passage through the Torres Strait during the late 18th and early 19th centuries was a dangerous exercise for European mariners. Apart from a maze of largely unmapped reefs, mariners had to negotiate passage through waters inhabited by resident Indigenous communities who had acquired a reputation for brutal attacks and cruel treatment of castaways. This paper explores circumstances behind the murder and mutilation of crew and passengers by Torres Strait Islanders from five ships attempting to transit the Strait – Shaw Hormuzear/Chesterfield (1793), Charles Eaton (1834), Thomas Lord (1846), and Sperwer (1869). Using anthropological recordings from the late 19th century, these mutilations are recast as acts of ritual processing explicable with reference to Torres Strait Islander ontology. The circumstances that coalesced to precipitate these mutilations were complex and rare and ultimately unrepresentative of the majority of frontier interactions between European mariners and Torres Strait Islanders, which were generally friendly and mutually beneficial.