Time‐dependent algorithms for viscoelastic flow: Finite element/volume schemes

Hybrid finite volume/element methods are investigated within the context of transient viscoelastic flows. A finite volume algorithm is proposed for the hyperbolic constitutive equation, of Oldroyd‐form, whereas the continuity/momentum balance is accommodated through a Taylor‐Galerkin finite element method. Various finite volume combinations are considered to derive accurate and stable implementations. Consistency of formulation is key, embracing fluctuation distribution and median‐dual‐cell constructs, within a cell‐vertex discretisation on triangles. In addition, we investigate the effect of treating the time‐term in a finite element fashion, using mass‐matrix iteration instead of the standard finite volume mass‐lumping approach. We devise an accurate transient scheme that captures the analytical solution at short and long time, both in core flow and near shear boundaries. In this respect, some difficulties are highlighted. A new method emerges, with the Low Diffusion B (LDB, with or without mass‐matrix iteration) as the optimal choice. We progress to a complex flow application and demonstrate some provocative features due to the influence of true transient boundary conditions on evolutionary flow‐structure in a 4:1 start‐up rounded‐corner contraction problem. © 2004 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2005     

Screen and Capacity of Predominant Strain for Toluene Biodegradation in Groundwater

The soil nearby a gas station was collected, from which we isolated a series of strains by means of enrichment and screening technigues. The most effective strain for the degradation of toluene, i.e.,.JYZ0315 was screened by the further mutation of the above strains. The degradation capacity experiment was carried out in simulated groundwater. Under the optimal conditions, the degradation rate could reach 93.5%. During the extend application experiments with a percolation tank, the degradation of toluene reached 87.3% in 11 d and 95.2% in 15 d. which was close to that of the microenvironment, and this proves that JYZ0315 is one of the oredominant strains to degrade toluene in groundwater.     

Bis(salicylaldiminate) copper(II) and palladium(II) complexes: towards columnar mesophases

Copper and palladium complexes of new salicylaldimines derived from 3,4,5-tridecyloxyaniline, 2,3,4-tridecyloxyaniline and 4-decyloxyaniline have been synthesized and characterized. All the ligands bear four or more aliphatic chains with the aim of inducing columnar mesophases at low temperatures. In particular, metal complexes derived from 4-(3,4,5-tridecyloxybenzoyloxy)-salicyliden-3,4,5-tridecyloxyaninile display rectangular columnar mesophases at (or near) room temperature. These mesophase assignments have been confirmed by X-ray diffraction. A significant decrease of the melting points of the compounds is observed in the tridecyloxyaniline derivatives compared with those of similar complexes derived from mono- or di-decyloxyaniline.     

A weighted eigencurve for Steklov problems with a potential

In this work, we study the existence of the principal eigencurves for a Steklov problem with an indefinite weight for homogeneous perturbation of the p-Laplacian operator. We then establish many properties of these eigencurves: continuity, differentiability and asymptotic behaviors. We also use our approach to get similar result when mixed Dirichlet–Steklov boundary condition is considered.