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121.
S.-M. Kwon H.-S. Choi K.-Y. Lee 《Archive of Applied Mechanics (Ingenieur Archiv)》2002,72(2-3):160-170
Summary The steady-state of a propagation eccentric crack in a piezoelectric ceramic strip bonded between two elastic materials under
combined anti-plane mechanical shear and in-plane electrical loadings is considered in this paper. The analysis based on the
integral transform approach is conducted on the permeable crack condition. Field intensity factors and energy release rate
are obtained in terms of a Fredholm integral equation of the second kind. It is shown for this geometry that the crack propagation
speed has influence on the dynamic energy release rate. The initial crack branching angle for a PZT-5H piezoceramic structure
is predicted by the maximum energy release rate criterion.
Received 23 January 2001; accepted for publication 18 October 2001 相似文献
122.
C.H. Rendell T.A. Ford Mavis Redshaw W.J. Orville-Thomas 《Journal of Molecular Structure》1975,24(1):187-204
Absorption spectra and dispersion curves have been obtained for dichloro-, dibromo- and diiodomethane in the liquid phase between 500 and 20 cm?1 using interferometric and Fourier spectroscopic techniques. The refractive index data extend existing information on these molecules to include all infrared active fundamental modes. Dispersion curves have also been obtained for deuterated dichloro- and dibromomethane, in the liquid phase, between 5000 and 450 cm?1.The refractive indices have been used to calculate absolute band intensities, dipole moment derivatives and vibrational polarizations. 相似文献
123.
T. Åkesson M.G. Albrow S. Almehed O. Benary H. Bøggild O. Botner H. Brody V. Burkert A. Di Ciaccio D. Cockerill S. Dagan E. Dahl-Jensen I. Dahl-Jensen G. Damgaard W.M. Evans C.W. Fabjan S. Frankel C. Woody 《Nuclear Physics B》1982,209(2):321-335
Calorimeters downstream of the intersection of pα and αα beams in the ISR have been used to study the hadronization of excited nucleons. These data extend and support the conclusions from previous studies of the A-dependence of particle multiplicities in ultrarelativistic p-nucleus collisions, which provided evidence that the proton hadronizes outside the nuclear volume. 相似文献
124.
A mixed discrete Fourier transform-Finite difference algorithm is developed and used for the calculation of rapidly changing viscous fluid flows past a circular cylinder. The numerical approach has been designed to overcome certain difficulties arising for high Reynolds number simulations. The foremost advantage of the technique lies in its fast calculations of the convolution sums portraying the convective terms of the governing equations. Third-order spatial discretizations and fourth-order time marching are implemented. New schemes are proposed for the boundary conditions at the solid wall and at large distances. The techniques are tested on a case study with other schemes (summarized by Roache1) in order to obtain an optimal choice. Definite indications on the stability and accuracy of boundary condition schemes are achieved. Support for the statement of dominant importance of boundary conditions is also given. A comparison of computational results with experimental data is presented for the case study of the flow past an impulsively started cylinder at Reynolds number 20. The time development of the symmetrical zone of recirculation, which is formed at an early stage of the flow, has been studied for 300 ≤ Re ≤ 9500 by means of the proposed algorithm. Computational results, comparisons with experimental data2 and discussion of upper limits of validity of the procedure will be presented in a companion paper. 相似文献
125.
Nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI) have been applied to visualize physiological phenomena in plants and agricultural crops. Imaging sequences that result in contrast of a combination of parameters (e.g., proton density,
) cannot be used for a correct and unique interpretation of the results. In this study multiecho imaging together with monoexponential T2 decay fitting was applied to determine reliable proton density and T2 distributions over a mushroom. This was done at three magnetic field strengths (9.4, 4.7, and 0.47 T) because susceptibility inhomogeneities were suspected to influence the T2 relaxation times negatively, and because the inflences of susceptibility inhomogeneities increase with a rise in magnetic field strength. Electron microscopy was used to understand the different T2's for the various tissue types in mushrooms. Large influences of the tissue ultrastructure on the observed T2 relaxation times were found and explained. Based on the results, it is concluded that imaging mushrooms at low fields (around or below 0.47T) and short echo times has strong advantages over its high-field counterpart, especially with respect to quantitative imaging of the water balance of mushrooms. These conclusions indicate general validity whenever NMR imaging contrast is influenced by susceptibility inhomogeneities. 相似文献
126.
F. A. Ptashchenko 《Journal of Applied Spectroscopy》1998,65(3):469-472
The kinetics of the decay in the electroluminescence intensity after gating a rectangular pulse of current in the p-n-transition
with inhomogeneities, in particular, accumulations of dislocations is calculated. The basic assumptions are: on gating the
rectangular pulse of current, a portion of the electrons injected into the thin p-region is extracted into the n-region, whereas
the same number of electrons are injected into the inhomogeneity where they recombine without emission; the intensity of nonradiative
recombination on the inhomogeneity is limited by drift of majority charge carriers (by leakages). It is shown that nonradiative
recombination on inhomogeneities leads to nonexponential kinetics of electroluminescence, whose instantaneous relaxation time
decreases with time.
Odessa State Naval Academy, 8 Didrikhson St., Odessa, 270029, Ukraine. Translated from Zhurnal Prikladnoi Spektroskopii, Vol.
65, No. 3, pp. 450–453, May–June, 1998 相似文献
127.
1.3μm场助TE光阴极In1-xGaxAsyP1-y/InP的能带计算及外延层的设计 总被引:1,自引:1,他引:0
本文首先简述了1.3μm场助TE光阴极InP(衬底)/In1-xGaxAsyP1-y(光吸收层)/InP(发射层)/Ag/CsO的工作原理,并对其能带结构进行了计算,得到了In1-xGaxAsyP1-y(光吸收层)/InP(发射层)的势垒高度、掺杂、InP发射层厚度、组份、渐变区宽度,偏压及耗尽层宽度间的定量关系。并由此出发,对光阴极各参数的设计进行了分析讨论。 相似文献
128.
顾熙棠 《宁波大学学报(理工版)》1988,(1)
本文对工作机械的相对振动进行了理论和实验研究。分析了相对振动的激励和合成原理,提出了工件和工具同相振动和异相振动、同相域以及相对振动放大因子等概念。在此基础上指出了减小相对振动的途径,以作为设计和改造工作机械的参考。 相似文献
129.
Richard A. Ferrell 《Journal of statistical physics》1973,8(3):265-278
The Schultz-Mattis-Lieb fermion formulation of the two-dimensional Ising model is simplified by means of long-wavelength approximations which become exact in the critical region. The resulting continuum theory has a Hamiltonian density which is shown to be identical, to within a perfect derivative, to that of free, spinless particles satisfying the one-dimensional Dirac equation. Filling the negative-energy single-particle states of momentumq and mass gives an integral over the single-particle energies -(
2+k2)1/2. Because varies linearly with the temperature, differentiating twice gives Onsager's logarithmic singularity in the specific heat.Work supported in part by the Office of Naval Research. 相似文献
130.
Gavrilov DN Kosobokova O Khozikov V Stepukhovitch A Gorfinkel V 《Electrophoresis》2005,26(18):3430-3437
A novel design of the detection zone in multicapillary arrays used for electrophoretic separation is presented. The use of a detection gap (DG), in which the reflective surfaces separating the channels of the array are eliminated, is proposed to improve the illumination and detection of the separated DNA fragments. The electric field compression in the DG is achieved by optimization of the gap geometry. The results of the computer simulation and experiment demonstrate no substantial band-broadening in the DG. We believe that the proposed method will be useful for application in the microfabricated devices. 相似文献