排序方式: 共有15条查询结果,搜索用时 15 毫秒
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U. K. Chettiar P. Nyga M. D. Thoreson A. V. Kildishev V. P. Drachev V. M. Shalaev 《Applied physics. B, Lasers and optics》2010,100(1):159-168
We have employed a parallelized 3D FDTD (finite-difference time-domain) solver to study the electromagnetic properties of
random, semicontinuous, metal films. The structural features of the simulated geometries are exact copies of the fabricated
films and are obtained from SEM images of the films themselves. The simulation results show good agreement with the experimentally
observed far-field spectra, allowing us to also study the nonlinear moments of the optical responses for these realistic nanostructures. 相似文献
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R. B. Nielsen M. D. Thoreson W. Chen A. Kristensen J. M. Hvam V. M. Shalaev A. Boltasseva 《Applied physics. B, Lasers and optics》2010,100(1):93-100
We report on the fabrication of two types of adjustable, near-field superlens designs: metal–dielectric composites and metal–dielectric
multilayer films. We fabricated a variety of films with different materials, thicknesses and compositions. These samples were
characterized physically and optically to determine their film composition, quality, and optical responses. Our results on
metal–dielectric composites indicate that although the real part of the effective permittivity generally follows effective
medium theory predictions, the imaginary part does not and substantially higher losses are observed. Going forward, it appears
that multilayer metal–dielectric designs are more suitable for sub-diffraction imaging applications because they could provide
both tunability and low loss. 相似文献
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Convection in chemical fronts enhances the speed and determines the curvature of the front. Convection is due to density gradients across the front. Fronts propagating in narrow vertical tubes do not exhibit convection, while convection develops in tubes of larger diameter. The transition to convection is determined not only by the tube diameter, but also by the type of chemical reaction. We determine the transition to convection for chemical fronts with quadratic and cubic autocatalysis. We show that quadratic fronts are more stable to convection than cubic fronts. We compare these results to a thin front approximation based on an eikonal relation. In contrast to the thin front approximation, reaction-diffusion models show a transition to convection that depends on the ratio between the kinematic viscosity and the molecular diffusivity. (c) 2002 American Institute of Physics. 相似文献
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Fritsch JM Thoreson KA McNeill K 《Dalton transactions (Cambridge, England : 2003)》2006,(40):4814-4820
An acyclic monoanionic tetradentate nitrogen ligand was prepared through the condensation of 2-(4-tolyl)-malondialdehyde and 8-aminoquinoline to give (BDI(QQ))H where (BDI(QQ))H = (8-quinolyl)-NCHC(4-tolyl)CHNH-(8-quinolyl). Metal complexes, (BDI(QQ))MX, were prepared where MX = MgBr 2, ZnCl 3, and CdOAc 4. The spectroscopic and crystallographic properties of compounds 2, 3, and 4 were explored. Structures of complexes 2, 3, 4, and the tridentate ligand, (BDI(Q))OH, 5, are reported. 相似文献
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Nedialko B. Dimitrov Dennis P. Michalopoulos David P. Morton Michael V. Nehme Feng Pan Elmira Popova Erich A. Schneider Gregory G. Thoreson 《Annals of Operations Research》2011,187(1):207-228
We describe a model for deploying radiation detectors on a transportation network consisting of two adversaries: a nuclear-material smuggler and an interdictor. The interdictor first installs the detectors. These installations are transparent to the smuggler, and are made under an uncertain threat scenario, which specifies the smuggler??s origin and destination, the nature of the material being smuggled, the manner in which it is shielded, and the mechanism by which the smuggler selects a route. The interdictor??s goal is to minimize the probability the smuggler evades detection. The performance of the detection equipment depends on the material being sensed, geometric attenuation, shielding, cargo and container type, background, time allotted for sensing and a number of other factors. Using a stochastic radiation transport code (MCNPX), we estimate detection probabilities for a specific set of such parameters, and inform the interdiction model with these estimates. 相似文献
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The surface roughness of a few asperities and their influence on the work of adhesion is of scientific interest. Macroscale and nanoscale adhesion data have seemingly given inconsistent results. Despite the importance of bridging the gap between the two regimes, little experimental work has been done, presumably due to the difficulty of the experiment needed to determine how small amounts of surface roughness might influence adhesion data lying in between the two scales. To investigate the role of few-asperity contacts in adhesion, the pull-off force was measured between different sized atomic-force microscope (AFM) tips (with different roughnesses) and sample surfaces that had well-controlled material properties. There were seventeen tips of four different types, with radii from 200 nm to 60 microm. The samples were unpatterned single crystal silicon with a chemical silicon dioxide surface resulting from a standard silicon wafer clean. Some of the samples were treated with a few angstroms of vapor deposited diphenylsiloxane. We observed that the uncorrected (for surface roughness) pull-off force was independent of the radius of the AFM tip, which was contrary to all continuum-mechanics model predictions. To explain this behavior, we assumed that the interactions between the AFM tip and sample were additive, material properties were constant, and that the AFM tip, asperities, and sample surfaces were of uniform density. Based on these assumptions, we calculated a simple correction due to the measured root mean square (RMS) surface roughness of the AFM tips. The simple correction for the RMS surface roughness resulted in the expected dependence of the pull-off force on radius, but the magnitudes were higher than expected. Commercial and heat-treated AFM tips have minimal surface roughness and result in magnitudes that are more reliable. The relative uncertainty for the pull-off force was estimated to be 10%. In this paper, we derive how the cantilever and tip parameters contribute to the measured pull-off force and show how the corrected results compare with theory. Although much work is still needed, the work presented here should advance the understanding of adhesion between the macroscale and nanoscale regimes. 相似文献
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P. Nyga V. P. Drachev M. D. Thoreson V. M. Shalaev 《Applied physics. B, Lasers and optics》2008,93(1):59-68
The optical properties of semicontinuous silver films have been studied in the mid infrared. The film extinction spectra are
shown to be well tailored by the deposition conditions and post-fabrication photomodification with both nanosecond and picosecond
laser pulses at 10.6 μm. The photomodification results in a decrease of the extinction above the laser wavelength. We find
that the induced changes in the optical responses of the films are both wavelength and polarization selective. This technique
allows the creation of long-pass filters for the mid-IR range in accord with the earlier theory. 相似文献