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991.
992.
Within the framework of modal control of large systems, a simple approach is advanced for the determination of optimal control configuration under an energy constraint, i.e., optimal locations of a limited number of controllers such that the total energy requirement for control is minimized. It is shown that the resulting design criterion is a simple function of projections of the control matrix onto components of eigenvectors associated with the affected eigenvalues. Furthermore, it is applicable to both single-input and multi-input systems. Systems possessing distinct complex eigenvalues are considered but the approach is equally applicable to other types of systems. Examples show that the minimum-energy control configuration also tends to be the most effective in terms of accomplishing control objectives. 相似文献
993.
B.K. Min 《Journal of the mechanics and physics of solids》1981,29(4):327-352
A plane stress analysis of the elastic-plastic deformation of unidirectional composites is presented. A continuum model based on the solid-mixture concept is selected as the basis for the analysis. Model parameters, including process-dependent variables, are deduced from experiments performed on unidirectional composites. A computer program MET1MAT has been developed accordingly and tested for a few simple in-plane loading cases. Experimental data for uniaxial tests performed in longitudinal and transverse directions and for a few biaxial tests are presented to substantiate the analysis. And, finally, application of the results to laminated metal matrix composites is discussed. 相似文献
994.
J. Badier J. Boucrot J. Bourotte G. Burgun O. Callot Ph. Charpentier M. Crozon D. Decamp P. Delpierre B. Gandois R. Hagelberg M. Hansroul Y. Karyotakis W. Kienzle P. Le D? J. Lefran?ois Th. Leray J. Maillard A. Michelini Ph. Miné G. Rahal O. Runolfsson P. Siegrist A. Tilquin R. Vanderhaghen S. Weisz NA Collaboration 《Zeitschrift fur Physik C Particles and Fields》1985,26(4):489-494
995.
G. M. Min’kov A. I. Ponomarev A. A. Sherstobitov S. G. Novokshonov A. A. Ivanov 《Physics of the Solid State》2005,47(10):1972-1979
Temperature and magnetic field dependences of the resistivity and Hall coefficient in layered single-crystal Nd2?xCexCuO4 (x = 0.12) films are experimentally investigated and analyzed. It is shown that this material clearly exhibits quantum effects characteristic of 2D semiconductor structures: negative magnetoresistance caused by suppression of the interference quantum correction by a magnetic field, a near-logarithmic temperature dependence of the conductivity, and a temperature dependence of the Hall coefficient related to e-e interaction. It is shown that, when analyzing experimental data, it is necessary to take interlayer transitions into account. Such an approach provides quantitative agreement between experiment and the standard theory of quantum corrections. 相似文献
996.
Ying?HeEmail author Wenbin?Sang Jun’an?Wang Ruofeng?Wu Jiahua?Min 《Journal of nanoparticle research》2005,7(2-3):307-311
The growth of the oriented zinc oxide (ZnO) nanorods on silicon substrates based on a simple novel chemical transformation and thermal hydrolysis by using polyvinyl alcohol (PVA) as self-assembling complex polymer was introduced in this paper. All the polymers were removed after chemical oxidation and only the carbonized grid backbones remained that confines the ZnO nanorod’s diameter and enhance the absorption and diffusion of ZnO at the tips of the nanorods during growth. The ZnO nanorods are investigated by FTIR, XRD and FE-SEM. The results indicated that these nanorods have fine hexagonal wurtzite crystal structure and their diameter varies from 20 to 90 nm and the length up to about 1 μm. A polymer-localized ZnO growth model is proposed, which well explains the growth behavior of ZnO nanorods.This revised version was published online in August 2005 with a corrected issue number. 相似文献
997.
A signal due to coherently excited vibrational motion has been observed in polydisperse silver nanoparticle samples. The particles were synthesized via a wet chemistry seed mediated method, which yields different particle shapes, including spheres, rods, and irregular triangular-shaped particles. The measured vibrational periods were compared to the results from continuum mechanics calculations. This analysis shows that the observed signal arises from the triangular-shaped particles, rather than the rods or spheres. The period of vibration increases as the dimensions of the triangular-shaped particles increase; specifically, we find that the period is given by 2h/c(l), where h is the bisector of the triangle and c(l) is the longitudinal speed of sound in silver. 相似文献
998.
We have experimentally investigated dynamical hysteresis behavior by changing the sweeping frequency of the cavity input field in the optical bistability of rubidium atoms (in a three-level atomic-type configuration) inside an optical cavity. The shape, width (or area), and direction of the hysteresis cycle are sensitive functions of the sweeping frequency for such an optical bistable system. 相似文献
999.
We propose and demonstrate a photonic phase shifter based a on vector-sum technique that uses polarization-maintaining fibers (PMFs). We achieved a continuous and full phase shift up to 2pi at 30.48 GHz by controlling the polarization state of the light injected into two pieces of PMF of different lengths and applying two different modulator bias voltages. 相似文献
1000.
We report the integration of inorganic nanotubes into metal-oxide-solution field effect transistors (FETs) which exhibit rapid field effect modulation of ionic conductance. Surface functionalization, analogous to doping in semiconductors, can switch the nanofluidic transistors from p-type to ambipolar and n-type field effect transistors. Transient study reveals the kinetics of field effect modulation is controlled by ion-exchange step. Nanofluidic FETs have potential implications in subfemtoliter analytical technology and large-scale nanofluidic integration. 相似文献