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Changes in the mechanical properties of a blood vessel when it remodels itself under stress are reviewed. One of the recent findings about blood vessels is the rapidity of tissue remodeling when the blood pressure is changed. When the tissue structure and material composition remodel, the zero-stress state of the vessel changes. The mechanical properties change also in the remodeling process. If the elastic behavior is expressed in terms of a pseudo-elastic strain-energy function, then the constants in the function will change in the course of the remodeling. With all these changes taking place, the scope of constitutive equations broadens: it should now include a mass-and-structure growth-stress relationship as well as a stress-strain-relationship. To obtain the mass-and-structure growth-stress relationship, one must be able to determine the mechanical properties of the different layers of the vessel wall, as well as the chemical composition and morphology. For the blood vessels, new methods of mechanical testing must be introduced. A key thought is to use bending of the blood vessel wall. By bending, different layers of the vessel wall are subjected to different stresses, leading to equations that can be used to solve the inverse problem of determining the stress-strain law from measured stress and strain. In vitro and in vivo experiments and theoretical prospectives are presented.

Discrete Global Grid Systems (DGGSs) are an emerging data model for integration and analysis of big Earth data. Current research on hexagonal DGGSs focuses mainly on the pure aperture, which limits application of resolution and may cause data redundancy. The mixed aperture hexagonal DGGS provides a new and flexible scheme that can optimize data precision by designing the most suitable grid resolution. This paper proposes a generic encoding and operation scheme for the mixed aperture 3 and 4 hexagonal DGGSs. A planar mathematical model with unique location representation was constructed. Based on this model, this paper designed an encoding scheme and gave relevant operational properties and rules. A generic method of extending the planar scheme to the surface of an icosahedron was then designed and spherical grids were obtained by projection. The conversion between geographical coordinates and codes was also provided. The proposed scheme has a more complete theoretical basis than existing schemes and can be applicable to different aperture sequences. Experiments show that the code addition efficiency of the proposed algorithm is superior to existing hexagonal grid systems. A case study with ocean salinity hexagonal data demonstrated the flexibility of the proposed scheme. [ABSTRACT FROM AUTHOR]

A series of composites of Ti5Si3/TiAl were synthesized by combination of mechanical alloying (MA) and hot isostatic pressing (HIPing). 20 h-milled powders of 65Ti–17Al–18Si (at.%) and 58Ti–21Al–21Si (at.%) were used as precursors incorporated into elemental 50Ti–50Al (at.%) powder matrices, followed by HIPing at 1100 °C and 150 MPa. Analyses by X-ray diffraction (XRD) as well as energy dispersive spectrometer (EDS) revealed the presence of three phases, namely, TiAl, Ti3Al and Ti5Si3. Observations by optical microscopy (OM) and scanning electron microscopy (SEM) showed features of equiaxed grain matrix (TiAl) with a number of distributed large clusters and small particles of Ti5Si3. The size of scattered distributed particles was estimated to be less than 1 μm while the large clusters and matrix grains are in the range of 10–50 μm. The mechanical properties of composites were evaluated by micro- and nano-hardness measurements and compression tests at ambient temperature. The alloys exhibited significant compressive deformability (10–20%) and pronounced strain hardening. While the matrices exhibited hardness of 4–7 GPa, the distributed Ti5Si3 particles indicated hardness of 10–12 GPa. [Copyright &y& Elsevier]

Based on the thermodynamic concept of exergy as a unified measure for environmental resources and economic products, a framework for systems assessment is presented for ecological economies. With a typical systems diagram devised for a general ecological economy with four arm fluxes for free local natural resources, purchased economic investment, environmental impact and economic yield, system indices of the renewability index, exergy yield ratio, exergy investment ratio, environmental resource to yield ratio, system transformity and environmental stress index are defined for a congregated systems ecological assessment with essential implications to sustainability. As a detailed case study to the Chinese agriculture from 1980 to 2000 with cropping, forestry, stockbreeding and fishery sectors, extensive exergy account and systems assessment are carried out with emphasis on annual and structural variations against social political transitions. For the overall agriculture as a congregated ecological stage, the value of the system transformity is found around 10, the typical value for the general ecological hierarchy as well devised by Odum associated with Lindeman''s Tenth Law. [Copyright &y& Elsevier]