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81.
82.
This article points at some critical issues which are connected with the theoretical formulation of the thermodynamics of
solid–fluid mixtures of frictional materials. It is our view that a complete thermodynamic exploitation of the second law
of thermodynamics is necessary to obtain the proper parameterizations of the constitutive quantities in such theories. These
issues are explained in detail in a recently published book by Schneider and Hutter (Solid–Fluid Mixtures of Frictional Materials
in Geophysical and Geotechnical Context, 2009), which we wish to advertize with these notes. The model is a saturated mixture
of an arbitrary number of solid and fluid constituents which may be compressible or density preserving, which exhibit visco-frictional
(visco-hypoplastic) behavior, but are all subject to the same temperature. Mass exchange between the constituents may account
for particle size separation and phase changes due to fragmentation and abrasion. Destabilization of a saturated soil mass
from the pre- and the post-critical phases of a catastrophic motion from initiation to deposition is modeled by symmetric
tensorial variables which are related to the rate independent parts of the constituent stress tensors. 相似文献
83.
84.
G. W. Englert 《Applied Scientific Research》1972,25(1):201-214
A model of the random walk is formulated to allow a simple computing procedure to replace the difficult problem of solution
of the Fokker-Planck equation. The step sizes and probabilities of taking steps in the various directions are expressed in
terms of Fokker-Planck coefficients. Application is made to many particle systems with Coulomb interactions. The relaxation
of a highly peaked velocity distribution of particles to equilibrium conditions is illustrated.
Part I of a thesis submitted in partial fulfillment of Doctor of Philosophy requirements at Colorado State University. 相似文献
85.
The adsorption of CO and O on Ni (111) was studied by low-energy ion scattering (ISS) and low-energy electron diffraction (LEED). For the ordered (√7/2) × (√7/2) R19.1° CO layer ion scattering gives a coverage greater than monolayer, and for the (2 × 2) O layer a coverage of monolayer. The CO is non-dissociatively adsorbed, with the C bound to the Ni. The molecules are oriented parallel to the surface normal. Island formation at lower CO coverages is possible. 相似文献
86.
The three methoxycarbonyl-substituted quadricyclanones 7a , 7b and 7c have been synthesized in good to excellent yields. Some of their physical (UV., NMR.) and chemical properties (e.g. condensation and pyrolysis reactions) are discussed. 相似文献
87.
Reinterpretation of the pioneering work of Nielsen and Olesen and others on magnetic confinement in (electric) superconductors leads to simple models which exhibit electric confinement of the type hoped for in quantum chromodynamics. “Electric” flux tubes joining “quarks” arise at a semi-classical level as a result of the existence of (pseudo) particles. The theory can be described in terms of a classical action principle only upon suitable modification of the action; this modification has profound topological significance as it is intimately related to the quantization condition for (pseudo) particles. 相似文献
88.
Devos A Simonetti AW van der Graaf M Lukas L Suykens JA Vanhamme L Buydens LM Heerschap A Van Huffel S 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2005,173(2):218-228
This study investigated the value of information from both magnetic resonance imaging and magnetic resonance spectroscopic imaging (MRSI) to automated discrimination of brain tumours. The influence of imaging intensities and metabolic data was tested by comparing the use of MR spectra from MRSI, MR imaging intensities, peak integration values obtained from the MR spectra and a combination of the latter two. Three classification techniques were objectively compared: linear discriminant analysis, least squares support vector machines (LS-SVM) with a linear kernel as linear techniques and LS-SVM with radial basis function kernel as a nonlinear technique. Classifiers were evaluated over 100 stratified random splittings of the dataset into training and test sets. The area under the receiver operating characteristic (ROC) curve (AUC) was used as a global performance measure on test data. In general, all techniques obtained a high performance when using peak integration values with or without MR imaging intensities. For example for low- versus high-grade tumours, low- versus high-grade gliomas and gliomas versus meningiomas, the mean test AUC was higher than 0.91, 0.94, and 0.99, respectively, when both MR imaging intensities and peak integration values were used. The use of metabolic data from MRSI significantly improved automated classification of brain tumour types compared to the use of MR imaging intensities solely. 相似文献
89.
McGuinness DS Wasserscheid P Keim W Morgan D Dixon JT Bollmann A Maumela H Hess F Englert U 《Journal of the American Chemical Society》2003,125(18):5272-5273
Cr(III) complexes of tridentate SNS ligands have been prepared and evaluated as catalysts for ethylene trimerization, with several giving very high activity and excellent selectivity toward 1-hexene when activated with methylaluminoxane. The new complexes illustrate the potential of sulfur-based ligands on early transition metals for catalysis. 相似文献
90.