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51.
Nernst R Antreasyan D Aschman D Besset D Bienlein JK Bloom ED Brock I Cabenda R Cartacci A Cavalli-Sforza M Clare R Conforto G Cooper S Cowan R Coyne D de Judicibus D Edwards C Engler A Folger G Fridman A Gaiser J Gelphman D Godfrey G Heimlich FH Hofstadter R Irion J Jakubowski Z Keh S Kilian H Kirkbride I Kloiber T Koch W König AC Königsmann K Kraemer RW Lee R Leffler S Lekebusch R Lezoch P Litke AM Lockman W Lowe S Lurz B Marlow D Maschmann W Matsui T Messing F Metzger WJ Monteleoni B 《Physical review letters》1985,54(20):2195-2198
52.
John R. Porter 《General Relativity and Gravitation》1982,14(11):1023-1033
The nonlinear graviton construction of Penrose is given explicitly for the nonlinear superposition of a finite number of plane waves with arbitrary propagation directions, phase, and amplitude profiles. These are realized as generalizedH-spaces for which the asymptotic data are distributional and have singular support on a finite number of null generators ofI
+. 相似文献
53.
54.
Tong Sun Subrata K. Bhattacharya Robert W. Lenz Roger S. Porter 《Journal of Polymer Science.Polymer Physics》1990,28(10):1677-1684
The copolyester containing 40 mol % ethylene terephthalate (PET) and 60 mol % p-hydroxybenzoate (HB) units has been reported by several investigators to be biphasic in the solid and the liquid states. The reported thermal transitions in the two phases, however, are in part contradictory, perhaps partly due to different polymerization conditions. The present work is a study of the transitions in each of the two phases of this copolyester by polarized light microscopy and by light transmission measurements. By light transmission measurements, the two phases were found to have two different glass transition temperatures for the onset of segmental motion, consistent with two assignable temperatures (T.). Cold crystallization and melting in each of the two different phases was also detected. The results help clarify the nature of transitions and agree with the results of dynamic mechanical analysis on the same thermotropic liquid crystalline copolyester. 相似文献
55.
Thompson I.; Linton C. M.; Porter R. 《The Quarterly Journal of Mechanics and Applied Mathematics》2008,61(3):333-352
The scattering of water waves by a long array of evenly spaced,rigid, vertical circular cylinders is analysed under the usualassumptions of linear theory. These assumptions permit the reductionof the problem to that of solving the Helmholtz equation intwo dimensions, with appropriate circular boundaries. Our primarygoal is to show how solutions obtained for semi-infinite arrayscan be combined to provide accurate and numerically efficientsolutions to problems involving long, but finite, arrays. Theparticular diffraction problem considered here has been chosenboth for its theoretical interest and for its applicability.The design of offshore structures supported by cylindrical columnsis commonplace and understanding how the multiple interactionsbetween the waves and the supports affect the field is clearlyimportant. The theoretical interest comes from the fact that,for wavelengths greater than twice the geometric periodicity,the associated infinite array can support Rayleigh–Blochsurface waves that propagate along the array without attenuation.For a long finite array, we expect to see these surface wavestravelling back and forth along the array and interacting withthe ends. For particular sets of parameters, near-trapping haspreviously been observed and we provide a quantitative explanationof this phenomenon based on the excitation and reflection ofsurface waves by the ends of the finite array. 相似文献
56.
57.
Summary The relationships between steady shear flow and dynamic rheology are investigated at relatively high shear rates and frequencies. A useful empirical relationship in this region predicts that the magnitude of the complex dynamic viscosity |
*| should be compared with the shear viscosity at equal values of frequency and shear rate (Cox-Merz-rule). Polystyrenes (PS) and Polyacrylamides (PAAm) have been investigated over a wide range of concentration and molecular weight. Only in case of PAAm/H2O solutions we have found that the results do not coincide with Cox-Merz-rule. As far as we know this is the first time that deviations from Cox-Merz-rule were observed in a homogeneous system. A molecular interpretation is given.
Presented at the IUPAC 26th International Symposium on Macromolecules, Mainz, September 17–21, 1979.
With 4 figures and 1 table 相似文献
Zusammenfassung Die Beziehung zwischen der Scherviskosität und der komplexen (dynamischen) Viskosität bei relativ hohen Schergeschwindigkeiten und Frequenzen wurde untersucht. Eine geeignete empirische Beziehung in diesem Bereich sagt aus, daß der Betrag der komplexen Viskosität | *| mit der Scherviskosität bei gleichen Werten von Frequenz und Schergeschwindigkeit vergleichbar ist (Cox-Merz-Regel). Polystyrole (PS) and Polyacrylamide (PAAm) wurden über einen weiten Bereich der Konzentration und des Molekulargewichts untersucht. Nur im Fall der PAAm/H2O-Lösungen wurden Abweichungen von der Cox-Merz-Regel gefunden. Soweit uns bekannt, ist es das erste Mal, daß Abweichungen von der Cox-Merz-Regel in einem homogenen System gefunden wurden. Eine molekulare Erklärung wird gegeben.
Presented at the IUPAC 26th International Symposium on Macromolecules, Mainz, September 17–21, 1979.
With 4 figures and 1 table 相似文献
58.
Filippo Cammaroto Andrei Catalioto Jack Porter 《Central European Journal of Mathematics》2011,9(6):1242-1251
In this article, we extend the work on minimal Hausdorff functions initiated by Cammaroto, Fedorchuk and Porter in a 1998
paper. Also, minimal Urysohn functions are introduced and developed. The properties of heredity and productivity are examined
and developed for both minimal Hausdorff and minimal Urysohn functions. 相似文献
59.
M. Gharebaghi K.J. Hughes R.T.J. Porter M. Pourkashanian A. Williams 《Proceedings of the Combustion Institute》2011,33(2):1779-1786
In this study, a mechanism for mercury chlorination in flue gases resulting from the combustion of pulverised coal has been presented. Arrhenius parameters of the gas-phase elementary reactions in the Hg–Cl sub-mechanism have been updated and are mainly based on recent experimental and quantum mechanical rate determinations. The mechanism is validated by comparison to accurate experimental data that is unbiased by Hg oxidation in the impinger solutions of aqueous chemistry methods. Solid-phase retention of Hg0 has been studied in parallel to char combustion; the heterogeneous model describes condensation of mercury on fly ash particles. The combined homogeneous–heterogeneous model predictions show comparable trends to those of power plant data. This approach aims to provide an improved prediction of mercury speciation from coal-fired power plants and to shed light on the chemical kinetic changes encountered during oxy-coal operation. 相似文献
60.