Fluid mechanics of turbomachines: a review

Future development of more efficient turbomachinery depends on improving understanding of the fluid mechanics. This paper reviews advances made in the last five years in calculation methods for steady flow, unsteady flows and stability, and instrumentation and its applications. Fundamental problems which need further study are also indicated     

Determination of submicromolar amounts of uranium(VI) by compleximetric titration with pyridine-2,6-dicarboxylic acid

Uranium(VI) is selectively determined by a compleximetric titration with pyridine-2,6-dicarboxylic acid, using arsenazo-I indicator and hexamethylenetetramine buffer at pH 4.9. Cyclohexanediaminetetraacetic acid and diethylenetriaminepentaacetic acid provide masking of interfering metal ions. A probe colorimeter apparatus is recommended for end-point detection. The relative standard deviation is 0.6% for 0.17–0.76 μmol of uranium.     

The concawe model for calculating the propagation of noise from open-air industrial plants

This paper describes a propagation model for calculating neighbourhood-noise from open-air industrial plants such as oil refineries and petrochemical plants. It was developed from a preliminary model derived from a comprehensive survey of the literature on noise propagation. The aim was to develop a model which used parameters and procedures available to engineers engaged in plant design. An experimental programme of measurements was carried out around three industrial plants over a period of about one year and this was used to modify the original model. The final model is based on six meteorological categories and contains separate attenuation values for spherical spreading, atmospheric absorption, ground effects, meteorological category, source/receiver height, and barrier effects. They are given as a function of frequency and distance, either as graphs or as polynomial equations for computer calculations.A statistical assessment has been made to establish the confidence limits of the predictions in dB(A) and in octave bands from 63 Hz to 4 kHz. They are compared with the confidence limits of predictions by two other propagation models frequently used in Europe (OCMA and VDI) and are found to be significantly better.     

Spin-Label EPR for Determining Polarity and Proticity in Biomolecular Assemblies: Transmembrane Profiles

Hyperfine couplings and g-values of nitroxyl spin labels are sensitive to polarity and hydrogen bonding in the environment probed. The dependences of these electronic paramagnetic resonance (EPR) properties on environmental dielectric permittivity and proticity are reviewed. Calibrations are given, in terms of the Block–Walker reaction field and local proton donor concentration, for the nitroxides that are commonly used in spin labeling of lipids and proteins. Applications to studies of the transverse polarity profiles in lipid bilayers, which constitute the permeability barrier of biological membranes, are reviewed. Emphasis is given to parallels with the permeation profiles of oxygen and nitric oxide that are determined from spin-label relaxation enhancements by using nonlinear continuous-wave EPR and saturation recovery EPR, and with permeation profiles of D₂O that are determined by using ²H electron spin echo envelope modulation spectroscopy.     

Event excess in the MiniBooNE search for ¯νμ→¯νe oscillations

The MiniBooNE experiment at Fermilab reports results from a search for ˉν_{μ}→ˉν_{e} oscillations, using a data sample corresponding to 5.66×102? protons on target. An excess of 20.9±14.0 events is observed in the energy range 475相似文献   

Charge, Geometry, and Effective Mass

Charge, like mass in Newtonian mechanics, is an irreducible element of electromagnetic theory that must be introduced ab initio. Its origin is not properly a part of the theory. Fields are then defined in terms of forces on either masses—in the case of Newtonian mechanics, or charges in the case of electromagnetism. General Relativity changed our way of thinking about the gravitational field by replacing the concept of a force field with the curvature of space-time. Mass, however, remained an irreducible element. It is shown here that the Reissner-Nordström solution to the Einstein field equations tells us that charge, like mass, has a unique space-time signature.