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191.
For fairly high concentrations, the effective arsenic diffusioncoefficient is known to grow linearly with the concentration.In this paper, we consider the strongly enhanced diffusion ofarsenic by asymptotic methods, and extend the results of a previouspaper (King & Please, 1987) in three ways: we characterizean additional (low-concentration) region; we consider the influenceof the initial data; and we consider the case of constant surfaceconcentration. 相似文献
192.
A monolithic grating surface-emitting, GaAs/AlGaAs, separate-confinement-heterostructure, single-quantum-well diode laser has been fabricated on a Si substrate using a single-step metalorganic chemical vapour deposition process. An output power of 30 mW has been obtained under pulsed operation with a peak emission wavelength of 885 nm.<> 相似文献
193.
Many analyses of boxed microstrip discontinuities require the location of large numbers of high-order modes. Using Sturm-Liouville theory, this letter derives a relationship between microstrip modes and slab-loaded guide modes, leading to an efficient mode location algorithm for microstrip, including microstrip with finite strip thickness.<> 相似文献
194.
195.
Grobnic D. Mihailov S.J. Smelser C.W. Ramos R.T. 《Photonics Technology Letters, IEEE》2008,20(12):973-975
Strong fiber Bragg gratings were written through the standard polymer coatings of "off-the-shelf" high numerical aperture single-mode optical fibers after a few seconds exposure with femtosecond pulse durations of infrared radiation through a phase mask. While writing through the acrylate coating, we obtained index modulations of up to 1.4 x 10-3 and 7 x 10-4 with and without H2 -loading, respectively. 相似文献
196.
Russomanno D.J. de Jongh Curry A.L. Atanasova G.S. Hunt L.C. Goodwin J.C. 《IEEE transactions on information technology in biomedicine》2008,12(1):76-86
DefibViz is a software application developed for defibrillation simulation and visualization. It exploits both surface techniques and methods for the interactive exploration of volumetric datasets for the analysis of transthoracic defibrillation simulation results. DefibViz has a graphical user interface for the specification of the shape, size, position, and applied voltage of a defibrillator's electrodes. An option is provided for using 3D slice plane widgets, which operate on the volumetric datasets, such that the distribution of the voltage gradient induced by an electric shock can be visually inspected in various tissues throughout the myocardium and torso. One goal of DefibViz is to enhance understanding of how electrode parameters relate to the change of the voltage gradient distribution throughout the heart, which may help lead to optimal defibrillator design. DefibViz is significant, in that, it is built by using an open-source graphics and visualization framework providing a platform for subsequent modifiability and extensibility. Moreover, it integrates simulation and visualization techniques, which previously required the running of several independent software executables, into an enhanced, seamless, and comprehensive software application. 相似文献
197.
Moore J.R. Collings N. Crossland W.A. Davey A.B. Evans M. Jeziorska A.M. Komarcevic M. Parker R.J. Wilkinson T.D. Xu H. 《Photonics Technology Letters, IEEE》2008,20(1):60-62
Polarization-insensitivity is achieved in a reflective spatial light modulator by laying a quarter-wave plate (QWP) at the incident wavelength directly over the mirror pixels of a silicon backplane, and forming a nematic Freedrickcz cell over the QWP to modulate the reflected phase. To achieve the highest drive voltage from the available silicon process, a switched voltage common front electrode design is described, with variable amplitude square wave drive to the pixels to maintain constant root-mean-square drive and minimize phase fluctuations during the dc balance refresh cycle. The silicon has been fabricated and liquid-crystal-on-silicon cells both with and without the QWP assembled; applications include optically transparent switches for optical networks, beam steering for add-drop multiplexers for wavelength-division-multiplexing telecommunications, television multicast, and holographic projection. 相似文献
198.
Carballo V.M.B. Chefdeville M. Fransen M. van der Graaf H. Melai J. Salm C. Schmitz J. Timmermans J. 《Electron Device Letters, IEEE》2008,29(6):585-587
An unpackaged microchip is used as the sensing element in a miniaturized gaseous proportional chamber. This letter reports on the fabrication and performance of a complete radiation imaging detector based on this principle. Our fabrication schemes are based on wafer-scale and chip-scale postprocessing. Compared to hybrid-assembled gaseous detectors, our microsystem shows superior alignment precision and energy resolution, and offers the capability to unambiguously reconstruct 3D radiation tracks on the spot. 相似文献
199.
Aji P. Mathew Gabriel Groeninckx G. H. Michler H. J. Radusch Sabu Thomas 《Journal of Polymer Science.Polymer Physics》2003,41(14):1680-1696
The effects of the blend ratio and initiating system on the viscoelastic properties of nanostructured natural rubber/polystyrene‐based interpenetrating polymer networks (IPNs) were investigated in the temperature range of ?80 to 150 °C. The studies were carried out at different frequencies (100, 50, 10, 1, and 0.1 Hz), and their effects on the damping and storage and loss moduli were analyzed. In all cases, tan δ and the storage and loss moduli showed two distinct transitions corresponding to natural rubber and polystyrene phases, which indicated that the system was not miscible on the molecular level. However, a slight inward shift was observed in the IPNs, with respect to the glass‐transition temperatures (Tg's) of the virgin polymers, showing a certain degree of miscibility or intermixing between the two phases. When the frequency increased from 0.1 to 100 Hz, the Tg values showed a positive shift in all cases. In a comparison of the three initiating systems (dicumyl peroxide, benzoyl peroxide, and azobisisobutyronitrile), the dicumyl peroxide system showed the highest modulus. The morphology of the IPNs was analyzed with transmission electron microscopy. The micrographs indicated that the system was nanostructured. An attempt was made to relate the viscoelastic behavior to the morphology of the IPNs. Various models, such as the series, parallel, Halpin–Tsai, Kerner, Coran, Takayanagi, and Davies models, were used to model the viscoelastic data. The area under the linear loss modulus curve was larger than that obtained by group contribution analysis; this showed that the damping was influenced by the phase morphology, dual‐phase continuity, and crosslinking of the phases. Finally, the homogeneity of the system was further evaluated with Cole–Cole analysis. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 1680–1696, 2003 相似文献
200.
R.J Hand 《Journal of Non》2003,315(3):276-287
Glass may be strengthened by epoxy coatings although the strengthening mechanisms remain unclear. Possible strengthening mechanisms are reviewed and are used to analyse strength data for both a solvent based and a water based coating system. The coatings either fill (solvent based coatings), or partially fill (water based coatings) surface cracks and it is shown that closure stresses arising from the thermal expansion mismatch of the coating within these cracks can account for the observed degrees of strengthening. It is also demonstrated that other suggested mechanisms such as flaw healing cannot fully account for the observed degree of strengthening. 相似文献