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101.
We use the adiabatic hyperspheric expansion and the Faddeev decomposition of the wave function with only s-waves. We derive for a fixed hyperradius an integro-differential equation for the angular eigenvalue and wave function. The
correlations lower the interaction energy for N = 20 by about a factor of 5.
Received October 22, 2001; accepted for publication November 5, 2001 相似文献
102.
TOPOLOGY DESIGN OF STRUCTURES SUBJECTED TO PERIODIC LOADING 总被引:5,自引:0,他引:5
C.S. JOG 《Journal of sound and vibration》2002,253(3):687-709
Although a lot of attention in the topology optimization literature has focused on the optimization of eigenfrequencies in free vibration problems, relatively little work has been done on the optimization of structures subjected to periodic loading. In this paper, we propose two measures, one global and the other local, for the minimization of vibrations of structures subjected to periodic loading. The global measure which we term as the “dynamic compliance” reduces the vibrations in an overall sense, and thus has important implications from the viewpoint of reducing the noise radiated from a structure, while the local measure reduces the vibrations at a user-defined point. Both measures bring about a reduction in the vibration level by moving the natural frequencies which contribute most significantly to the measures, away from the driving frequencies, although, as expected, in different ways. Quite surprisingly, the structure of the dynamic compliance optimization problem turns out to be very similar to the structure of the static compliance optimization problem. The availability of analytical sensitivities results in an efficient algorithm for both measures. We show the effectiveness of the measures by presenting some numerical examples. 相似文献
103.
J. S. Chiou J. W. Barlow D. R. Paul 《Journal of Polymer Science.Polymer Physics》1987,25(7):1459-1471
The miscibility of bisphenol-A polycarbonate (PC) with poly(methyl methacrylate) (PMMA) has been reexamined using differential scanning calorimetry (DSC) and optical indications for phase separation on heating, i.e., lower critical solution temperature (LCST) behavior. Various methods have been used to prepare the blends including methylene chloride (CH2Cl2) and tetrahydrofuran (THF) solution casting, melt mixing, and precipitation of PC and PMMA simultaneously from THF solution by using the nonsolvents methanol and heptane. It is shown that the resulting phase behavior for PC/PMMA blends is strongly affected by the blend preparation method. However, these blends are miscible over the whole blend composition range (unambiguous single composition-dependent Tg's and LCST behavior) when prepared by precipitation from solution using heptane as the nonsolvent. To the contrary, solution-cast and melt-mixed PC/PMMA blends were all phase separated, which may be attributed to the “solvent” effect and LCST behavior, respectively, not discovered in previous reports. Methanol precipitation does not lead to fully mixed blends, which demonstrates the importance of the choice of nonsolvent when using the precipitation method. 相似文献
104.
The effects of surface preparation and illumination on electric parameters of Au/InSb/InP(100) Schottky diode were investigated, in the later diode InSb forms a fine restructuration layer allowing to block In atoms migration to surface. In order to study the electric characteristics under illumination, we make use of an He-Ne laser of 1 mW power and 632.8 nm wavelength. The current-voltage I(VG), the capacitance-voltage C(VG) measurements were plotted and analysed. The saturation current Is, the serial resistance Rs and the mean ideality factor n are, respectively, equal to 2.03 × 10−5 A, 85 Ω, 1.7 under dark and to 3.97 × 10−5 A, 67 Ω, 1.59 under illumination. The analysis of I(VG) and C(VG) characteristics allows us to determine the mean interfacial state density Nss and the transmission coefficient θn equal, respectively, to 4.33 × 1012 eV−1 cm−2, 4.08 × 10−3 under dark and 3.79 × 1012 eV−1 cm−2 and 5.65 × 10−3 under illumination. The deep discrete donor levels presence in the semiconductor bulk under dark and under illumination are responsible for the non-linearity of the C−2(VG) characteristic. 相似文献
105.
An experimental method for determining the real-time depth of laser-drilled holes is presented. The proposed method involves
detecting the laser-induced optoacoustic waves generated during the interaction of the laser beam with the material. Our optodynamic
study involved measuring the propagation times of these waves as they traveled through the material and analyzing their temporal
behavior during the drilling process. The experimental observations revealed an exponential relationship between the propagation
time of the longitudinal stress wave and the number of consecutive laser pulses.
Received: 25 October 2001 / Accepted: 27 October 2001 / Published online: 20 December 2001 相似文献
106.
107.
G. S. Asanov 《Foundations of Physics Letters》2002,15(2):199-207
Granted the post-Lorentzian relativistic kinematic transformations are described in the Finslerian framework, the uniformity between the actual light-velocity anisotropy change and the anisotropic deformation of measuring rods can be the reason proper for the null results of the Michelson-Morley-type experiments at the first-order level. 相似文献
108.
F. Ameli M. Bonori F. Massa 《The European Physical Journal C - Particles and Fields》2002,25(1):67-75
We describe the measurement of the deep sea optical background in some sites south of Capo Passero, Sicily. A continuous
flux of about 440 photons cm
-2
s
-1
in the wavelength interval 440-550 nm is estimated due to the decays of the 40K contained in the sea water. Bioluminescence light bursts are also observed and an example of time evolution is reported.
All the measurements were accomplished using a deep sea module also described in this article.
Received: 20 April 2002 / Published online: 26 July 2002 相似文献
109.
On mechanical characteristics of nanocrystals 总被引:2,自引:0,他引:2
The dependence of the elastic moduli of a nanocrystal on its size is investigated theoretically with reference to a two-dimensional single-crystal strip. It is shown that the uncertainty (of a fundamental nature) in the size of a nanocrystal causes the determination of many of its mechanical characteristics to be ambiguous. It is found that the Cauchy-Green relations are modified and the elastic-constant tensor ceases to be symmetric; the size and shape of a nanocrystal render its mechanical properties more anisotropic. For a single-crystal strip, the Poisson ratio decreases and the Young modulus increases with decreasing thickness of the strip; in the case of a very thin crystal film (two atomic layers thick), these elastic moduli can differ from their macroscopic values by a factor of two. The size effects which make the continuum elasticity theory inapplicable to nanocrystals are estimated. The size effects that occur when the molecular dynamics method is applied for modeling macroscopic objects are also discussed. 相似文献
110.
V. I. Vettegren V. A. Marikhin V. B. Kulik L. S. Titenkov 《Physics of the Solid State》2002,44(12):2341-2346
The temperature dependence of the expansion ?C of trans conformers of the carbon skeleton of macromolecules in crystallized and amorphous poly(ethylene terephthalate) (PET) due to zero-point and thermal atomic vibrations is investigated by IR spectroscopy. It is found that the thermal expansion coefficient βC jumpwise increases at the characteristic temperatures T t and T b. This increase is associated with the crossover from the quantum to classical statistics of torsional and bending vibration modes. The quantum and classical contributions to the expansion ?C are determined for each mode. The quantum and classical contributions of the torsional vibrational mode in the amorphous polymer are approximately 1.5 times larger than those in the crystallized polymer. This effect is caused by an increase in the anharmonicity of torsional vibrations in the amorphous polymer. 相似文献