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71.
Ülo Lepik 《International Journal of Non》1981,16(1):19-26
A rigid plastic beam under implusive loading is considered. In order to increase the stiffness of the beam, some additional supports are applied. The locations of these supports must be selected so as to minimize the maximal permanent deflection of the beam. This problem is solved with the aid of the optimal control theory of distributed parameter systems. Optimality conditions are deduced. The case where the problem is self-conjugate is examined. An example is given. 相似文献
72.
The heat transfer from a surface heated with constant heat flux to an oscillating vertical annular liquid column having an
interface with the atmosphere is investigated experimentally in the present paper. The analysis is carried out for the case
of different oscillation frequencies while the displacement amplitude remains constant. Based on the experimental data a correlation
equation is obtained for the cycle-averaged Nusselt number as a function of kinetic Reynolds number. 相似文献
73.
74.
Glass-Maujean M Jungen Ch Roudjane M Tchang-Brillet WÜ 《The Journal of chemical physics》2011,134(20):204305
New experimental energy levels for the 2pπC(1)Π(u)(-) state of D(2) are reported extending up to the dissociation limit and including rotational quantum numbers up to N = 10. These data are extracted from recent high resolution optical emission spectra, and they are used for a detailed comparison of two theoretical approaches, both of which are fully ab initio and are based on the same state-of-the-art clamped-nuclei potential energy curves. These are the coupled differential equations (CE) and the multichannel quantum defect theory (MQDT) approaches, each of which accounts for adiabatic corrections and non-adiabatic couplings. Both theoretical approaches reproduce the experimental levels to within a fraction of a wavenumber unit (cm(-1)) for the lower vibrational quantum numbers, with the MQDT surpassing the CE method. As the dissociation limit is approached, the residuals observed-calculated increase up to several cm(-1) and the MQDT method is up to a factor of two less accurate than the CE method. The same analysis is carried out with existing data for the H(2) isotopomer and yields similar results. An analogous comparison is also made for the 3pπD(1)Π(u)(-) and 4pπD('1)Π(u)(-) states for both isotopomers, where the MQDT is found to be superior to the CE approach. 相似文献
75.
J. BOIDEN PEDERSEN MARTIN J. HANSEN ANATOLE A. NEUFELD MASANOBU WAKASA HISAHARU HAYASHI 《Molecular physics》2013,111(9):1349-1354
Magnetic field effects on the hydrogen abstraction reaction of 4-methoxybenzophenone with thiophenol in several solvents of different viscosity have been reported, and the observed magnetic field dependence was explained as caused by the Δg and a polarized initial triplet radical pair state. The present work reports a quantitative analysis of the data based on a recently derived general analytical formula. It is found that the observed magnetic field dependence can be explained as originating from an unpolarized triplet state, if both the coherent mixing caused by different g values of the two radicals and the incoherent mixing due to spin relaxation are included. Several different expressions for the magnetic field dependence of the longitudinal and transverse relaxation rates were applied. Rather surprisingly, the different models gave almost identical fits. However, the values obtained of the microscopic parameters depended significantly on the model. Physically sensible parameter values were obtained only when the complete magnetic field dependence of the two relaxation times were used. For this model it was found that both the anisotropy factor of the g tensors and the diffusion coefficient agreed with expectations. 相似文献
76.
The Helmholtz free energy of highly charged plates immersed in an electrolyte solution in a finite container is investigated using mean field theory. Exact solutions of the Poisson-Boltzmann equation under Dirichlet and Neumann boundary conditions lead to analytical expressions for the free energies. Adiabatic potentials of the charged plates, which are derived from the free energy, have long-range weak attractive parts and medium-range strong repulsive parts, irrespective of the type of boundary conditions. The repulsion results mainly from the osmotic pressure of the excess ions trapped between the plates by the large surface charges and the attraction arises essentially from an electric pull from the intermediate cloud of excess counterions shared by the plates. 相似文献
77.
K. Ünlü C. Rios-Martinez B. W. Wehring 《Journal of Radioanalytical and Nuclear Chemistry》1995,193(1):145-154
A Prompt Gamma Activation Analysis (PGAA) facility is being developed at The University of Texas at Austin (UT). The UT-PGAA facility will utilize a focused cold-neutron beam from the Texas Cold Neutron Source (TCNS). the TCNS consists of a cold source cryostat and a curved neutron guide. the use of a guided focused cold-neutron beam will provide a high capture reaction rate and low background. The UT-PGAA facility will be used in the nondestructive determination of B, Cd, Gd and S in biological and environmental samples. 相似文献
78.
Nuri Ünal 《Foundations of Physics》1997,27(5):747-758
Barut's classicalzitterbewegung model includes the internal dynamical variables and the quantization of this system gives a general transition amplitude
between the different space-time points and internal coordinates and momentum. It includes the transition amplitude between
the half integer and integer spin eigenvalues. Spin eigenfunctions lead to all sets of relativistic wave equations, as well
as the Dirac equation. 相似文献
79.
CLAIRE BOISSET HENRI CHANZY MARTIN SCHULEIN BERNARD HENRISSAT 《Cellulose (London, England)》1997,4(1):7-20
Because cellulases are finding more applications in the textile and detergent industries, their effect on cotton fibres must
be evaluated. For this purpose, the action of a recombinant cellulase, endoglucanase V from the fungus Humicola insolens,
has been followed by scanning electron microscopy (SEM) in classical longitudinal views as well as in cross-sections of cotton
fibres. The experiments were conducted at large enzyme dilution typical of conditions where cellulases are used for biopolishing,
i.e. for the removal of defects created by mechanical abrasion. Endoglucanase V appears to restrict its action to the hydrolysis
of the loose fibrils created at the surface of the fibres and no indication of extensive enzyme penetration and damage to
the interior of the fibres could be detected by SEM. The adsorption sites for endoglucanase V on cotton fibres were examined
by transmission electron microscopy (TEM) on ultrathin cross-sections after immuno-gold labeling of the enzyme. This approach
showed that the enzymes did not penetrate the fibres but remained at their surface. The use of an immuno-gold labeled cellulase
provides a new way to probe the surface features of cotton fibres
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
80.