Treatment of Natural Geometry in Finite Volume River Flow Computations

A method is proposed for the treatment of irregular bathymetry in one-dimensional finite volume computations of open-channel flow. The strategy adopted is based on a reformulation of the Saint-Venant equations. In contrast with the usual treatment of topography effects as source terms, the method accounts for slope and nonprismaticity by modifying the momentum flux. This makes it possible to precisely balance the hydrostatic pressure contributions associated with variations in valley geometry. The characteristic method is applied to the revised equations, yielding topographic corrections to the numerical fluxes of an upwind scheme. Further adaptations endow the scheme with an ability to capture transcritical sections and wetting fronts in channels of abrupt topography. To test the approach, the scheme is first applied to idealized benchmark problems. The method is then used to route a severe flood through a complex river system: the Tanshui in Northern Taiwan. Computational results compare favorably with gauge records. Discrepancies in water stage represent no more than a fraction of the magnitude of typical bathymetry variations.     

High-Throughput Experimentation in Oxidation Catalysis

High-throughput experimentation in catalysis comprises the following components: (i) automated high-throughput synthesis, (ii) testing in Stage I and Stage II, for which to some extent novel assays are necessary, (iii) data handling and experimental design tools, and (iv) robotics. This contribution covers these topics, using examples from the research of the authors, but also from the literature, in order to illustrate the problems and opportunities associated with high-throughput experimentation in catalysis, focusing particularly on heterogeneous catalysis.     

Nuclear orientation of recoil-implanted52Mn in Au down to 3 mK

Measurements of the -ray anisotropy of recoil-implanted⁵²Mn ions in pure Au down to 3 mK indicate marked deviations from free-ion behavior in low applied fields. The effective hyperfine field that explains the anisotropy is found to decrease below 10 mK. Although this behavior could be a signature of a bound Kondon state with a lower effective hyperfine coupling constant, it is better explained as arising from a combination of Kondo and relaxation effects. The data indicate that the Mn local moment relaxation timeT ₁ is comparable to or larger than the Larmor precession time of the Mn nuclei at 3 mK. Other possible reasons for an attenuated -ray anisotropy, such as nuclear quadrupole and second-order crystal field effects, are also considered.This work was supported by the Bundesministerium für Forschung und Technologie.     

Measurement technique for pump and signal background absorption oferbium-doped fibres

An explicit analytical expression for the transmission of pump and signal power through an erbium-doped fibre in the presence of background loss is given. Because the solution is explicit, it can easily be fitted to measurement results. This leads to a simple method For determining the erbium absorption constant, saturation power and fibre background absorption constant. The technique is demonstrated for wavelengths of the signal range     

Single Crystals of HgBa2Can−1CunO2n+2+δ (n=1−5) and Layers of HgBa2CuO4+δ Grown at Gas Pressure 10 kbar

Single crystals of Hg-12(n?l) have been grown using high-pressure gas-technique. Due to the high density of Ar gas at 10 kbar the evaporation of Hg is strongly suppresed. An influence of structure defects on magnetic properties will be discussed. Superconducting parameters λ _ab ,ξ _ab and γ have been studied using torque magnetometry. Layers of Hg-1201 compound have been grown from flux.     

Does disclosure of emotions facilitate recovery from bereavement? Evidence from two prospective studies.

Two longitudinal studies assessed whether disclosure of emotions facilitates recovery from bereavement. Study 1 tested prospectively over a 2-year period whether the extent to which bereaved persons talked about their loss to others and disclosed their emotions was associated with better adjustment to the loss of a marital partner. There was no evidence that disclosure facilitated adjustment. Study 2 randomly assigned recently bereaved individuals either to the Pennebaker writing task (J. W. Pennebaker & S. K. Beall, 1986) or to no-essay control conditions. The writing task did not result in a reduction of distress or of doctors visits either immediately after the bereavement or at a 6-month follow-up. Beneficial effects were not demonstrated for bereaved persons who had suffered an unexpected loss or who at the time of the study still expressed a high need for emotional disclosure. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Measurement technique for the quotient of cross sections /spl sigma//sub e/(/spl lambda//sub s/)//spl sigma//sub a/(/spl lambda//sub s/) of erbium-doped fibers

A method for the measurement of the quotient of the emission and absorption cross section of erbium-doped fibers is presented which utilizes the spontaneous emission perpendicular to the fiber axis. The maximum population of the first excited state achievable through illumination by signal light (/spl lambda//sub s/=1530 nm) is fixed by the quotient of the absorption and the emission cross section. This fact is used to determine the desired quotient. First measurements show that this method is very simple and highly accurate.<>