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71.
72.
For a real Enriques surface Y we prove that every homology class in H1(Y (R), Z/2) can be represented by a real algebraic curve if and only if all connected components of Y(R) are orientable. Furthermore, we give a characterization of real Enriques surfaces which are Galois-Maximal and/or Z-Galois-Maximal and we determine the Brauer group of any real Enriques surface Y. 相似文献
73.
Tetsuya Okuyama Masaru Nakayama Yoshitsugu Tomokiyo Omer Van Der Biest 《Microscopy and microanalysis》2002,8(1):11-15
Lattice strains around a platelet oxygen precipitate in Si wafer is studied by energy filtering convergent-beam electron diffraction (CBED) and calculations based on the finite element method (FEM). Local lattice strains are measured from CBD patterns obtained with a probe size less than 2 nm in a specimen thicker than 450 nm. Strains measured are compressive along a direction normal to a plate of the precipitation and tensile along a direction parallel to the plate. Two-dimensional stress fields near the precipitate are obtained with FEM computer analyses by fitting the measured strains. It appears that shear stresses are concentrated at the end of the precipitate edge and the maximum shear stress at an interface between the precipitate and the Si-matrix is 1.9 GPa. It is demonstrated that a combination of the energy filtering CBED and FEM is very useful for the study of local strains near interfaces in semiconductor devices, in particular for the study of stress fields that are too steep for application of the conventional CBED technique. 相似文献
74.
Supported by a Heisenberg-scholarship of the DFG 相似文献
75.
Der‐Jang Liaw Ching‐Cheng Huang En‐Tang Kang 《Journal of polymer science. Part A, Polymer chemistry》2006,44(9):2901-2911
Diblock copolymers of 5‐(methylphthalimide)bicyclo[2.2.1]hept‐2‐ene (NBMPI) and 1,5‐cyclooctadiene were synthesized by living ring‐opening metathesis polymerization with a well‐defined catalyst {RuCl2(CHPh)[P(C6H11)3]2}. Unhydrogenated diblock copolymers showed two glass transitions due to poly(NBMPI) and polybutadiene segments, such as two glass‐transition temperatures at ?86.5 and 115.3 °C for poly 1a and ?87.2 and 115.3 °C for poly 1b . However, only one melting temperature could be observed for hydrogenated copolymers, such as 119.8 °C for poly 2a and 121.7 °C for poly 2b . The unhydrogenated diblock copolymer with the longer poly(NBMPI) chain (poly 1a ; temperature at 10% mass loss = 400 °C) exhibited better thermal stability than the one with the shorter poly(NBMPI) chain (poly 1b ; temperature at 10% mass loss = 385 °C). Two kinds of hydrogenated diblock copolymers, poly 2a and poly 2b , exhibited relatively poor solubility but better thermal stability than unhydrogenated diblock copolymers because of the polyethylene segments. Poly[(hydrochloride quaternized 2‐norbornene‐5‐methyleneamine)‐b‐butadiene]‐1 (poly 3a ) was obtained after the hydrolysis and quaternization of poly 1a . Dynamic light scattering measurements indicated that the hydrodynamic diameters of the cationic copolymer (poly 3a ) in water (hydrodynamic diameter = 1580 nm without salt), methanol/water (4/96 v/v; hydrodynamic diameter = 1500 nm without salt), and tetrahydrofuran/water (4/96 v/v; hydrodynamic diameter = 1200 nm without salt) decreased with increasing salt (NaCl) concentration. The effect of temperature on the hydrodynamic diameter of hydrophobically modified poly 3a was also studied. The inflection point of the hydrodynamic diameter of poly 3a was observed at various polymer concentrations around 30 °C. The critical micelle concentration of hydrophobically modified poly 3a was observed at 0.018 g dL?1. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 2901–2911, 2006 相似文献
76.
Asymptotic expansions for the exponential growth rate, known as the Lyapunov exponent, and rotation numbers for two coupled oscillators driven by real noise are constructed. Such systems arise naturally in the investigation of the stability of steady-state motions of nonlinear dynamical systems and in parametrically excited linear mechanical systems. Almost-sure stability or instability of dynamical systems depends on the sign of the maximal Lyapunov exponent. Stability conditions are obtained under various assumptions on the infinitesimal generator associated with real noise provided that the natural frequencies are noncommensurable. The results presented here for the case of the infinitesimal generator having a simple zero eigenvalue agree with recent results obtained by stochastic averaging, where approximate ItÔ equations in amplitudes and phases are obtained in the sense of weak convergence.Dedicated to Thomas K. Caughey on the occasion of his 65th birthday. 相似文献
77.
78.
79.
C L Van Doren G A Gescheider R T Verrillo 《The Journal of the Acoustical Society of America》1990,87(5):2201-2206
The ability of subjects to detect temporal gaps between bursts of sinusoids or bursts of bandlimited noise was measured to evaluate the phenomenon of tactile "sensory persistence" in older persons. Vibratory stimuli were delivered to the right thenar eminence of 27 subjects ranging in age from 8-75 years. The subjects' task was to detect the presence of a silent interval or "gap" between flanking 350-ms vibrotactile stimuli. The gap-detection threshold, expressed as the amplitude of vibration relative to the absolute detection threshold, decreased as the gap duration increased and was higher for gaps in noise than for gaps in sinusoids. The threshold for detecting short gaps increased with age for noise stimuli, but not for sinusoidal stimuli. Furthermore, the gap-detection threshold recovered more rapidly in older subjects for noise stimuli, but less rapidly in older subjects for sinusoidal stimuli. Because of these differences, it appears that the effects of age on gap detection cannot be due to a simple increase in sensory persistence, but may be due to multiple processes. 相似文献
80.
In this paper, we adapt the octahedral simplicial algorithm for solving systems of nonlinear equations to solve the linear complementarity problem with upper and lower bounds. The proposed algorithm generates a piecewise linear path from an arbitrarily chosen pointz
0 to a solution point. This path is followed by linear programming pivot steps in a system ofn linear equations, wheren is the size of the problem. The starting pointz
0 is left in the direction of one of the 2
n
vertices of the feasible region. The ray along whichz
0 is left depends on the sign pattern of the function value atz
0. The sign pattern of the linear function and the location of the points in comparison withz
0 completely govern the path of the algorithm.This research is part of the VF-Program Equilibrium and Disequilibrium in Demand and Supply, approved by the Netherlands Ministry of Education, Den Haag, The Netherlands. 相似文献