Field Testing of Stabilized Soil

Remediation of a Superfund site in Stratford, Conn., involved stabilization of the subgrade with portland cement. Part of the remediation site was to be used as a parking area. The stabilized soil was to be covered with natural base∕subbase course materials and capped with an asphalt concrete cover. During the course of the remediation, a base-course layer could not be placed prior to the onset of winter. A field study was conducted to quantify any changes in the mechanical properties of the open stabilized subgrade subjected to freeze-thaw cycling during the winter of 1996–97. Field evaluation was conducted with pavement industry tools: the Clegg impact hammer and the dynamic cone penetrometer. Evaluation results show the viability of the Clegg hammer as an instrument for quality assurance and also show that there can be up to 50% loss in compressive strength of the subgrade within the uppermost layer of the material caused by freeze-thaw cycling.     

Identification of inorganic pigments used in porcelain cards based on fusing Raman and X-ray fluorescence (XRF) data

Raman spectroscopy and X-ray fluorescence (XRF) spectroscopy are often used as complementary techniques that are well suited for the analysis of art objects because both techniques are fast, sensitive, and noninvasive and measurements can take place in situ. In most of these studies, both techniques are used separately, in the sense that the spectra are evaluated independently and single conclusions are obtained, considering both results. This paper presents a data fusion procedure for Raman and XRF data for the characterization of pigments used in porcelain cards. For the classification of the analyzed points of the porcelain cards principal component analysis (PCA) was used. A first attempt was made to develop a new procedure for the identification of the pigments using a database containing the fused Raman-XRF data of 24 reference pigments. The results show that the classification based on the fused Raman-XRF data is significantly better than the classifications based on the Raman data or the XRF data separately.     

Emittance measurements of solids above 2000 deg C

A method of measuring the emittance of solids above 2000 deg C through the use of a solar furnace has been developed. Two techniques involving specialized instrumentation, for performing the necessary measurements were investigated. Initial experiments showed that both techniques were suitable and that the specified instruments were adaptable for making the required measurements.     

Microstructural aspects of neutron embrittlement of reactor pressure vessel steels - A view from positron annihilation spectroscopy

A comprehensive review of positron annihilation studies of Cr---Mo---V reactor pressure vessel (RPV) steels (Soviet type 15Kh2MFA) in unirradiated and neutron irradiated states is presented. The influences of lattice defects, impurity atom distribution, irradiation temperature, flux and fluence of fast neutrons on positron annihilation parameters, especially during isochronal annealing, are discussed in terms of the positron trapping model. In contrast to the literature, where irradiation-enhanced Cu precipitates and solute coated microvoids are thought to be major defect types responsible for strengthening and hence embrittling of RPV steels, we suggest irradiation-induced precipitates, i.e. probably carbides, to play this role. Possibilities to probe this model are suggested.     

Stress computations for nearly incompressible materials by the p-version of the finite element method

In the case of nearly incompressible elastic materials the strain energy, the shear stress and the difference of normal stresses can be computed accurately by direct methods when the p-version of the finite element method is used. Computation of the sum of the normal stresses requires special procedures. In this paper such procedures are described and examples are presented.     

Interaction of nonionic polymers at a clay interface

The structure and dynamics at the interface of swelling clays (smectites) are crucial to such diverse applications as drilling for oil, cosmetics, paints, water treatment, or chemical reactions. From our previous NMR studies on clay suspensions, we have shown how the orientation of interfacial molecules is affected by the clay structure1, by the nature of counterions 2, or by the composition of the liquid phase3. These results have been mainly obtained from the analysis of residual quadrupolar splittings of nuclei from interfacial species. In this work, we report our studies on a clay montmorillonite suspended in aqueous solutions of non ionic polymers. The polymer perturbs the structure within the interfacial region as deduced from the variations of the splittings of water quadrupolar nuclei and of sodium-23 relaxation parameters in terms of the polymer concentration. Proton self-diffusion coefficients and carbon-13 relaxation times are measured to describe the influence of the clay on the polymer mobility. The dependence of the polymer nature on these parameters is also investigated.     

Zur Berechnung von Wirbelkernhalbmessern in rotationssymmetrischen Drallströmungen

Zusammenfassung Drei der bedeutendsten Verfahren zum Berechnen des Wirbelkernhalbmessers in rotationssymmetrischen Drallstr?mungen werden miteinander verglichen. Zwar liegt jedem dieser Verfahren eine Energieberechnung zugrunde; die Ergebnisse unterscheiden sich jedoch erheblich voneinander. Es wird die Ursache jener Abweichungen untersucht und festgestellt, da? das von K. Bammert vorgeschlagene Verfahren nur mit Berücksichtigung der Volumflu?verteilung die gleichen Ergebnisse wie die Berechnungsverfahren von E. Meldau und M. Strscheletzky liefert. Ferner geht aus der Untersuchung die Bedeutung der Axialgeschwindigkeitsverteilung hervor. Die Verwendbarkeit dieser Verfahren bleibt dadurch auf jene F?lle beschr?nkt, in denen der Drall und die Axialgeschwindigkeit in der betrachteten achsnormalen Ebene konstant sind.     

Compact spectrum splitting photovoltaic module with high efficiency

We have designed, fabricated, and tested a small, integrated photovoltaic module comprised of two separately‐contacted, high efficiency, multijunction solar cells and non‐imaging optics that both concentrate and spectrally split the incoming light. This hybrid design allows us to individually optimize the tandem cells and optical elements. The system has a measured module efficiency, including optical and packaging losses but not power combination losses, of 38.5 ± 1.9% under the AM1.5 direct terrestrial spectrum. The internal optics concentrate the light by a factor of approximately 20. We find excellent agreement between the modeled and measured performance. This is the highest confirmed conversion efficiency demonstrated for a photovoltaic module. Copyright © 2010 John Wiley & Sons, Ltd.