INSTANTANEOUS OPTIMAL CONTROL FOR SEISMIC ANALYSIS OF NON-LINEAR STRUCTURES

In this paper, an effective active control algorithm is developed for the vibration control of non-linear structural systems subjected to earthquake excitation. It is an attempt to include the non-linear characteristics of the structural behaviour throughout the entire analysis (design and validation), accounting for the eventual cumulative structural damage and energy dissipation. This is a very important factor since, in current design practice, structures are assumed to behave nonlinearly when subjected to strong ground motion. The proposed algorithm focusses on the instantaneous optimal control approach for the development of the control algorithm where the nonlinearities are brought into the analysis through a non-linear state vector and a non-linear open loop term. A performance index that is quadratic in the control force and in the non-linear states and is subjected to a non-linear constraint equation, is minimised at every time step. The effectiveness of the proposed non-linear instantaneous optimal control (NIOC) strategy is critically evaluated in comparison with currently available active control techniques. Numerical simulation results indicate that the proposed approach provides a significant reduction of the peak response quantities, such as maximum response deformation, maximum response acceleration, ductility of the system, associated with a reduced maximum control force.     

SEISMIC ENERGY DEMAND IN STEEL MOMENT FRAMES

The present paper investigates the seismic energy demand in steel moment-resisting frames. The frames, with 3, 6 and 10 storeys, and 4 and 8 spans, are designed according to current seismic code provisions. The energy response (energy quantities and their distributions) in the frames subjected to an ensemble of six earthquake ground motions recorded on different soil conditions, is investigated by nonlinear time history analysis. The study concludes that (1) the results of energy response can be developed into a rational method of seismic evaluation and design for steel moment-resisting frames; (2) the energy concept based on the single-degree-of-freedom has limitations when extended to the realistic structural system for design purposes; and (3) it is necessary to develop the energy-based approach for seismic evaluation and design based on the seismic response of a realistic multi-degree-of-freedom structural system.     

Ivane Tarkhnishvili (Tarchanoff): A Major Georgian Figure from the Russian Physiological School

This article is dedicated to one of the outstanding scientists of the nineteenth century: Ivane Tarkhnishvili (Tarchanoff), a Russian physiologist of Georgian origin who graduated from the St. Petersburg Medico-Surgical Academy and worked under the supervision of the founder of Russian physiology, Ivan Sechenov. Among his numerous contributions was the discovery of the skin galvanic reflex; however, Tarkhnishvili's most significant contribution was the discovery of the influence of X-rays on the central nervous system, animal behavior, the heart and circulation, and embryonic development. Indeed, these works have given rise to a new field in science (radiobiology).     

新中国成立初期的灾害救助工作

1949～1952年,为战胜严重的自然灾害,中国共产党和人民政府通过采取临灾救济、生产救灾、安置灾民等措施遏制了灾害的进一步恶化,巩固了新生的人民政权,提高了中国共产党的执政能力。新中国成立初期,党和政府积累了一定的灾害救助经验,即:加强对灾害救助工作的领导,实行抗灾工作总动员;制定切实的灾害救助方针;注意加强灾害管理;及时向灾区派出视察组、慰问团;发挥非政府救济组织的作用。     

Technical Strategies for Conservation of Earthen Archaeological Architecture

The preservation of earthen architectural heritage is extremely complex due to the diversity of its constituent materials and potentially rapid physical deterioration. Interventions on historic earthen architecture throughout the world have shown very distinct levels of success, but there is no single procedure or combination of conservation procedures that guarantee success. One of the problems is the lack of knowledge about the behaviour of soil as the material component, and its relationships both with other materials, and associated natural and cultural environments. This article analyses some technical considerations that have influenced the preservation of earthen archaeological remains, through critical analysis of the existing bibliographic references from the proceedings of specialized international conferences that have taken place in the last twenty years.     

中部地区典型煤炭城市接续产业响应模式分析及比较

在煤炭城市转型的基础上采取适宜的转型路径和适当的响应模式,是煤炭城市实现可持续发展的必须条件。本文基于产业生命周期发展理论,在确定中部地区典型煤炭城市接续产业的前提下,利用SOFM模型,将中部地区典型煤炭城市发展接续产业响应模式进行了系统分类,并确定了具体的四类响应模式及相应阶段的特征,最后针对城市煤炭城市接续产业响应模式提出了相应的政策建议。     

蒙东地区与东北三省煤炭资源开发的区域合作研究

我国蒙东地区与东北三省煤炭资源开发的区域合作是建设新兴的蒙东资源基地和振兴东北老工业基地的必然要求。通过在蒙东地区及东北三省的深入调查,发现这两大区域煤炭资源开发的区域合作已经形成一些典型案例,可以分别从上级政府强势干预、地方政府积极推动、中央、地方、企业联动、企业自发参与这四种模式来认识这些案例所反映的区域合作特征、效应与问题。为深入推进蒙东与东北三省煤炭资源开发的区域合作,政府干预应着重协调区域合作的地区格局,促进企业的多元参与,建设跨地区运输通道与生态工程,推进地方政府间的配合与协调。     

建国以来女性教育的成果、问题及对策

女性的教育状况是衡量女性在社会中地位高低的主要标志之一.新中国建立后制定的有关法律和法规,新的教育体制的确立以及开展的女性扫盲运动、女性基础教育、高等教育、研究生教育、留学教育和继续教育等实践,使中国女性在提高了政治和社会地位的同时,也提高了文化知识水平和科学技术的应用能力.教育是立国之本,而女性教育更关系到民族的兴亡和国家的盛衰.占中国人口一半以上的女性自身素质和文化水平曾对建国以来的社会发展产生过很大影响,并将继续对21世纪中国科技、经济、社会的走向产生巨大的影响.     

传统村落文化对城乡一体化的统筹性响应机理

后改革时代中国的城乡发展亟需改变以往城市偏向型发展观导向下忽视甚至漠视乡村的发展,逐步转向区域同步发展观下的城乡统筹协调发展。城乡一体化实质上是城乡联动发展中不断实现城乡文化共融的过程。传统村落是整体上延续并传承了我国优秀传统文化的典型乡村聚落,乡土文化是其区别于城市文化的独特价值所在。本文从文化地理学视角,从"地方性"角度重新定义传统村落并剖析其文化空间和空间的文化价值,探讨城乡一体化对传统村落文化及其空间演变的综合影响,最后提出传统村落文化对城乡一体化的统筹性响应策略。     

Climate change and Zhou relocations in early Chinese history

In Chinese history, the development of the Zhou tribes and the dynasties that succeeded them between 3550 and 2200 BP in the middle reaches of the Yellow River is known as the period of ‘Five Relocations’. Most of these relocations appear to have been forced by the pressure of nomadic invasions and occupations from the northern steppe. Historians simply attributed these relocations to political and military causes. However, palaeoclimatic studies show that the Zhou tribes and their successor dynasties developed at the demise of the Holocene Climatic Optimum when regional climate became highly variable and unstable. An integrated analysis of environmental change over the Loess Plateau and the Mongolian steppe facilitates a credible understanding of the linkage between climatic events and these relocations. It indicates that the relocations caused an expansion or contraction of the settled regions over the drought-prone semi-arid lands. During climatic amelioration, dry farming societies pushed upward to the Loess Plateau where increased precipitation and soil moisture allowed cereals to be cultivated. When hit by droughts and the associated disasters, both the dry farming societies and the nomadic tribes had to move southward to find an environment suitable for their food production. Migration and relocation were, therefore, basic strategies to secure the resources necessary to sustain an agricultural economy. The settled frontier was pulled back as dry farming societies from the upland plateau retreated to the lowland riverbanks of the Guanzhong Basin. Even though there were political and military intentions, climatic events played an essential role in the relocations of the Zhou tribes and the successive dynasties.