The flow of the viscous fluid around the sphere in the range Re ⪝ 2

Summary An improved and more correct solution of Oseen's equations, when the flow of the incompressible viscous fluid around the sphere is concerned, has been suggested. The new Oseen's correction term of the Stokes solution for the resistant force and drag coefficient has been derived. The dependencec _w(Re), together with the relative deviations, has been plotted considering three types of solutions (Oseen's, Stokes' and our's).     

Ellipsometrische Charakterisierung von C‐Schutzschichten für die Speichertechnologie

Spectroscopic Ellipsometry is a fast, non‐destructive and reliable method for characterizing thin films, based on interaction between incident light and a multilayer system. For our investigations, light in the visible spectral range has been used to characterize protective carbon coatings with thicknesses of 2‐7nm on magnetic hard disks. The specific disk layer stack has been described with an adequate one‐layer model. With regard to an accurate analysis of the covering carbon coating a reproducible procedure for determining the underlying metallic material has been developed. The measured ellipsometric parameters (ψ, Δ) display a linear dependence on carbon film thickness which shows an appropriate application of the used model down to a thickness of 2 nm. By means of simulation calculations, criteria for the selection of optimized wavelengths with respect to film characterization has been established. Furthermore, an increasing extinction coefficient κ with rising nitrogen content in the carbon coating could be stated. Apparent time instabilities in the determination of layer thickness d and extinction coefficient κ of the carbon film could be explained as due to adsorption processes on the surface.     

承上启下：50年代生中国建筑师

《时代建筑》计划在2012—2013年这两年时间的3期杂志里,以10年为剖切面,对＂50后＂、＂60后＂和＂70后＂3个中国当代建筑师群体（以下简称＂50、60、70年代生建筑师＂）进行系统且整体的梳理与研究。这批建筑师经历了中国轰轰烈烈的改革开放带来的经济快速发展的浪潮,参与了中国30年城市快速扩张背景下的大规模建设,成就了无数的新城新区和高楼大厦,也创作了一批具有时代意义的作品。无疑,这是一群对当代中国建筑发展具有重要作用,并且正在发生影响的一线建筑师。我们不仅会对这批建筑师进行群体研究,而且会对其中的优秀代表进行个体分析,关注他们30多年来的成长,关注他们对当代中国建筑问题的思索,关注他们的建筑实践。     

Einführung in die Neuausgabe von DIN 1045-1

Introduction in the New Edition of DIN 1045-1 Resulting from editing of the National Annex of the new European design standard for concrete structures Eurocode 2 and under consideration of experiences with the use and interpretation of the German design standard a consolidated new edition of DIN 1045-1 is published in 2008. In this paper the changes and their backgrounds in the new edition of DIN 1045-1 are explained. This paper will clarify the new or changed rules for – the moisture classes because of alkali-silica-reaction (ASR) – the concrete cover – the effective creep coefficient – the temperature intervals for steel characteristics – the minimum shear resistance – the shear interfaces – the increase of shear for punching at wall-end and -corner – the reinforcing steel fatigue characteristics – the crack width limiting minimum reinforcement for thick members – the transverse reinforcement in the lap zone and at columns – the ductility reinforcement     

Research program on the selection of materials and processes for component parts

It is now widely accepted that the final cost of a manufactured product is largely determined at the design stage. The research programme described in this paper addresses decisions that must be made early in the design procedure, namely the selection of suitable processes and materials for the proposed component parts of the product. Generally, designers will tend to conceive parts in terms of the processes and materials with which they are familiar and may, as a consequence, exclude from consideration process and process/material combinations that may have proved more economic. A satisfactory method for the systematic selection of suitable process/material combinations for part manufacture is not currently available. Such a method is being developed and implemented in a computer environment for use during the early stages of product design.     

Model based prognosis of contaminant leaching for reuse of demolition waste in construction projects

In this study, groundwater contamination from recycled demolitian waste in road constructions is assessed using predictions of leachate concentrations. Numerical transport simulations are performed for three scenarios (a parking lot, a noise protection barrier, and road), and using a number of characteristic subsoils of Germany, to estimate the breakthrough of different contaminant classes at the groundwater table. Conservative tracer breakthrough times (BTT) primarily depend on subsoil hydraulic properties, for organic pollutants KOC and subsoil OC are the controlling parameters. Significant concentration reductions from dispersion only occur when source concentrations decrease prior to contaminant breakthrough. If source concentrations remain high for long periods relative to peak BTT, concentration breakthrough is undamped. Accounting for biodegradation reduces breakthrough concentrations significantly. For the “noise protection barrier” and “road” scenarios, capillary barrier effects cause the seepage water to partially bypass the recycling material. Accounting for this bypass flow and spatial averaging across the constructions reduces concentrations by about 30–40?%.     

Influence of mineral precipitation on the performance and long-term stability of Fe 0 -permeable reactive barriers: A review on the basis of 19 Fe 0 -reactive barrier sites

A comparative evaluation of the monitoring results from 19 Fe⁰-permeable reactive barriers (PRBs) is presented which considers changes of groundwater composition within the Fe⁰-PRBs, the type and distribution of mineral phases that precipitate, porosity reductions, extent of the load of inorganic groundwater constituents and the overall performance. The findings show that the changes in groundwater composition within the PRBs are extremely similar, independent of flow velocities, residence times, and concentrations of inorganic substances. In addition, the type and distribution of mineral precipitates do not show great variances with the largest mineral accumulations within the first 10 to 30 cm from the entrance face of the PRBs. From these comparisons it can be concluded that loads of dissolved inorganic species higher than 200 kg?·?a^–1?·?m^–2 limit the long-term performance of Fe⁰-PRBs up to a few years due to porosity losses caused by mineral precipitation, independent of the type of construction. Moreover, detailed calculations of porosity and hydraulic conductivity decreases of the PRBs at the Rheine and Tübingen sites show that the influence of mineral fouling on the hydraulic permeability of a PRB can only be estimated by accounting for the interaction between reduction in porosity, permeability and flow rate. The findings suggest that it is possible to pre-estimate the porosity and permeability development for a potential PRB.     

Are more restrictive food cadmium standards justifiable health safety measures or opportunistic barriers to trade? An answer from economics and public health

In the past, Cd regulations have imposed trade restrictions on foodstuffs from some developing countries seeking to access markets in the developed world and in recent years, there has been a trend towards imposing more rigorous standards. This trend seems to respond more to public and private sectors strategies in some developed countries to create disguised barriers to trade and to improve market competitiveness for their industries, than to scientifically justified health precautions (sanitary and phytosanitary measures) and/or technical barriers to trade acceptable under the Uruguay Round Agreement of the WTO. Applying more rigorous Cd standards in some developed countries will not only increase production costs in developing countries but it will also have a large impact on their economies highly dependent on international agricultural markets. In the current literature there are large uncertainties in the cause-effect relationship between current levels of Cd intakes and eventual health effects in human beings; even the risk of Cd to kidney function is under considerable debate. Recent works on the importance of zinc:Cd ratio rather than Cd levels alone to determine Cd risk factors, on the one hand, and on the declining trends of Cd level in foods and soils, on the other, also indicate a lack of scientific evidence justifying more restrictive cadmium standards. This shows that developing countries should fight for changing and making more transparent the current international structures and procedures for setting sanitary and phytosanitary measures and technical barriers to trade.