Palaeoenvironmental analysis based on alluvial ostracod assemblages of the Cenicero section (lower Miocene, NW Ebro Basin)

In this work we perform for the first time a palaeoenvironmental and biostratigraphic analysis of the lower Miocene alluvial deposits of the Cenicero section (NW sector of the Ebro Basin; N Iberian Peninsula), based on the ostracod and micromammal assemblages. One of the main characteristics of this section is the unusual abundance on non-reworked ostracods present in the studied samples compared to other European sequences of similar age and sedimentary environment. This fact has allowed us to develop precise palaeoenvironmental reconstructions. The variations of the identified ostracod assemblages, defined by species such as Cyclocypris laevis, Ilyocypris bradyi, Ilyocypris gibba, Limnocythere sp. or Pseudocandona parallela, record the development of small, ephemeral and shallow ponds in a distal alluvial and/or floodplain environment. Towards the upper part of the section the ponds appear to be less ephemeral, being the aquatic systems more stable for ostracods development. Variations in the water temperature and salinity have been observed along the section, which are related to changes in the local pluviometric regime. On the other hand, the presence of micromammals in one of the studied samples has allowed the precise dating of this section. Thus, the presence of Armantomys daamsi dates the Cenicero section as Agenian (lower Miocene), local zone Y2 (MN2).

Detached-eddy simulation of transonic flow past a fan-blade section

Detached-eddy simulation of transonic flow past a thin section of a fan blade has been carried out. The inflow Mach number is 1.03, and a bow shock forms upstream of the blade. The shock (corresponding to an adjacent blade) impinges on the suction-side boundary layer which causes separation and rapid transition to turbulence. The boundary layer later re-attaches near the trailing edge. The pressure-side boundary layer transitions near the leading edge and remains attached. Mean surface pressure shows basic agreement with a steady RANS calculation; strong shock motion in the DES is the major cause of discrepancy. Surface pressure spectra are investigated, and low-frequency two-dimensional disturbances associated with the shock motion are dominant. Removing the two-dimensional component from the spectra, the pressure-side three-dimensional spectra reproduce the spectral shape given by a correlation for flat-plate boundary layer wall-pressure spectra developed by Goody. 1 The suction-side disturbances produce similar high- and intermediate-frequency scalings despite substantially different boundary layer development. Near-wake results show that disturbance kinetic energy peaks at the suction-side inflection point of the mean profile, and that the energy is concentrated at low frequencies relative to the near-trailing edge surface pressure. Copyright © 2009 by the authors.

Some new bounds on eigenvalues of the Hadamard product and the Fan product of matrices

Let A and B be nonsingular M-matrices. A lower bound on the minimum eigenvalue q(B circle A(-1)) for the Hadamard product of A(-1) and B, and a lower bound on the minimum eigenvalue q(A star B) for the Fan product of A and B are given. In addition, an upper bound on the spectral radius rho(A circle B) of nonnegative matrices A and B is also obtained. These bounds improve several existing results in some cases and the estimating formulas are easier to calculate for they are only depending on the entries of matrices A and B. (C) 2009 Elsevier Inc. All rights reserved.