Impact wave propagation in tall buildings using advanced spectral element method

One of the major divisions in analysis and design of tall buildings is to account for forces induced by flying‐object impact and the subsequent progressive collapse. During the past three decades, problems of contact mechanics have been considered by some authors, and special attention has been devoted to high‐speed impact. Impact wave propagation in tall buildings may be analysed using the conventional finite element method. However, in order to guarantee stability and accuracy of the solution, the number of elements used to model the structure may be very large indeed; more precisely, accurate results can be obtained after a substantial computational effort. In this respect, an improved complex spectral element method is developed for analysing the wave propagation problems in large structures. The purpose of this paper is to obtain the resulting dynamic responses of a tall building induced by a high‐speed impact of a flying object. Copyright © 2003 John Wiley & Sons, Ltd.     

Stable lead isotopes and lake sediments--a useful combination for the study of atmospheric lead pollution history

Analysis of stable lead isotopes and lead concentrations in lake-sediment deposits, not least in varved (annually-laminated) sediments, is a useful method to study lead pollution history. This paper presents details from a study of 31 lakes in Sweden. Using a strong acid digestion of sediment samples and ICP-MS analyses, we have found that Swedish lake sediments have a high natural (pre-pollution) 206[Pb]207[Pb] ratio (mean 1.52+/-0.18, range 1.28-2.01, n=31 lakes). In contrast, atmospheric lead pollution derived from metal smelting processes, coal burning and from alkyl-lead added to petrol has a lower ratio (< 1.2). Consequently, when pollution lead deposition began approximately 3500 years ago, the lead isotope ratio of the sediments started to decline, and in modern sediments it is typically < 1.2. Using the isotope and concentration values and a mixing model, the relative contribution of pollution and natural lead in sediment samples can be calculated. The pollution lead records of the Swedish lake sediments show a consistent picture of the atmospheric lead pollution history. Some noticeable features are the Roman peak (approx. 0 AD), the large and permanent Medieval increase (approx. 1000 AD), peaks at approximately 1200 and 1530 AD, the rapid increase after World War II, the peak in the 1970s, and the large modern decline.     

Long-term geophysical observations on the inguri dam rock foundation

Bulletin of Engineering Geology and the Environment - It has been found that during construction of the dam, prior to the filling of the reservoir, compaction and loading of the rocks under the...     

Experience with algal blooms and the removal of phosphorus from sewage

The growth of algae and occurrence of algal “blooms” in a number of different waters are described.They cover the period 1930–1940 when only natural phosphates would be present.The waters were drawn from either protected catchments or from a fully treated domestic supply.Spasmotic blooms in a fully treated domestic supply suggest that the mechanism which “triggers” the start of an algal bloom may be neither nutrient concentration nor the concentration of organic matter.It is considered that the pH, alkalinity, carbon dioxide equilibrium condition is a major factor, not only in promoting, but also in maintaining algal blooms.     

行动导向的棚户区改造规划编制方法探讨——以南京江北新区为例

在分析棚户区改造主要难点基础上,认为传统清单式的棚户区改造计划已经无法适应新的棚户区改造要求,需要探索兼具理性价值、统筹能力与可操作性的棚户区改造规划新范式。结合《南京江北新区棚户区改造行动规划》的实践,提出了棚户区改造规划编制需要解决的4项关键任务,以及需要贯穿编制过程的3条技术逻辑线。     

Technique for measuring metallic salt effects upon the indigenous heterotrophic microflora of a natural water

The effects of several concentrations of the metallic salts Ag₂SO₄, NaAsO₃, BaCl₂2H₂O, CdCl₂2.5 H₂O, CrCl₂6H₂O, CuCl₂, HgCl₂, NaCl, NiCl₂6H₂O, PbCl₂ and ZnCl₂ upon the indigenous heterotrophic microflora of a natural water were studied. Effects of these salts upon the heterotrophic activity of the microbes were assayed using the heterotrophic technique whereas lethal effects upon the heterotrophic bacteria were determined using nutrient agar plate counts. The heterotrophic activity method is based upon the uptake and mineralization of a radioactively labeled metabolite (in these experiments ¹⁴C-glucose) by the indigenous aquatic microbes and data analysis is by Michaelis—Menten enzyme kinetics equations. Concentrations of metallic salts which resulted in bacterial death also caused erratic uptake and mineralization rates of ¹⁴C-glucose whereas sub-lethal concentrations, as determined by nutrient agar plate counts, caused a non-competitive inhibition of maximum heterotrophic activity and markedly increased the turnover time of the glucose substrate.     

Earthquake analysis of isotropic asymmetric multistory buildings

Isotropic multistory buildings are the ones characterized by the property: all load‐resisting planar frames have proportional lateral stiffness matrices. In the present paper it is proved that the modal analysis of an N‐story isotropic asymmetric, torsionally coupled, building (a problem of order 3N) can be separated into two independent sub‐problems: (a) a sub‐problem that corresponds to a single‐story asymmetric, torsionally coupled, building (a problem of order 3); and (b) a sub‐problem that corresponds to an N‐story, torsionally uncoupled, planar frame (a problem of order N). It is also demonstrated that the orientation of peak modal seismic forces of the building is independent of the orientation of seismic excitation, which affects only their size. The separation provides a better insight into the structural behavior of asymmetric multistory buildings under earthquake ground motion. Copyright © 2006 John Wiley & Sons, Ltd.     

舟山桃花岛桃花湾景观旅游规划探析

近些年大量游客涌入以及由此引出的各种服务设施建设造成了风景区自然景观严重的破坏，使风景区内原定的自然审美功能严重丧失。以浙江舟山群岛桃花岛桃花湾景观旅游规划为例，探析风景区规划新思路。在对舟山桃花湾现状和景观资源进行的科学分析基础上，规划着重探讨了旅游度假风景区的规划布局以及沿海沙滩景观的保护和利用，力求达到规划的生态效益、经济效益、人文效益和社会效益的统一。     

The Italian national survey of indoor radon exposure

An investigation is being developed by the Camitato Nazionale per la Ricerca e per lo Sviluppo dell'Energia Nucleare e delle Energie Alternative, ENEA, to assess the indoor exposure of the Italian population. The programme, which started in 1982, includes regional and local surveys in all the administrative districts and intensive investigations of factors which influence indoor radon levels. The survey is organized by statistical areas of sampling to obtain representative samples of houses. The definition of the areas takes into account basic parameters e.g. geolithological environments, radon soil gas from underlying soils and rocks, specific activities of local building materials, climatic and seasonal variations, building technology, types of houses and town planning. The collected data may also be used for the compilation of radon risk maps to plan special monitoring and remedial actions if needed. Preliminary results concerning the above items are discussed.