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11.
We introduce a solver and preconditioning technique based on Domain Decomposition and the Fast Diagonalization Method that can be applied to tensor product based discretizations of the steady convection–diffusion equation. The method is based on a Robin–Robin interface preconditioner coupled to a fast diagonalization solver which is used to efficiently eliminate the interior degrees of freedom and perform subsidiary subdomain solves. Using a spectral element discretization, we first apply our technique to constant wind problems, and then propose a means for applying the technique as a preconditioner for variable wind problems. We demonstrate that iteration counts are mildly dependent on changes in mesh size and convection strength. © 2009 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2011  相似文献   
12.
It has been shown that the use of submonolayer InAs insertions as an active region of AlGaAs vertical cavity surface emitting lasers make it possible to attain resonant frequencies as high as 17 GHz. In this case, single-mode devices with a smaller diameter of the current aperture make it possible to attain higher frequencies at lower current densities than those of multimode devices with a larger aperture diameter. The maximum error-free data transmission rate in the direct modulation mode in NRZ format is 20 Gb/s and is limited by the parasitic cutoff frequency. The high resonant frequency suggests that further optimization of the device design, directed to decreasing the electrical capacitance and resistances, the data transmission rate in lasers based on submonolayer insertions can be increased to 40 Gb/s.  相似文献   
13.
The characteristics of 25.5 MHz one-hop mode propagation on a 950 km Alaskan path, over a one-year period shortly after sunspot maximum are presented as a function of the “planetary geomagnetic index-Kp”. The location of the E-region reflection point lies within the auroral oval for 3相似文献   
14.
As the aperture size of oxide-apertured vertical-cavity surface-emitting lasers (VCSELs) shrinks, the lasing wavelength blueshifts. We have calculated this effect using both a scalar effective index model and a full-vector weighted index model. Results were compared against experimental data for two different VCSEL designs emitting near 780 and 850 nm. We find that the full-vector weighted index calculation matches the data remarkably well, while the scalar effective index calculation underestimates the blueshift  相似文献   
15.
Visible (670-nm) resonant cavity light-emitting diodes (RCLEDs) composed entirely of AlGaInP alloys are discussed. The devices consist of a strained quantum well optical cavity active region surrounded by AlInP/(AlGa)InP distributed Bragg reflectors (DBRs). The bottom DBR is a 60.5 period high reflector while the top partial reflector, which determines the emission linewidth, is a five-period output coupling DBR with a reflectance of about 57%. The devices exhibit linewidths of 4.8 nm (13.3 meV) at 300 K and are promising for plastic fiber communication systems and monochromatic displays  相似文献   
16.
The analysis of thermal insulation materials by optical microscopy has centered on the identification of fibrous constituents and not the bulk insulation. To enhance the identification of insulation, procedures were developed using chemical spot tests and microscopical observations that included dispersion staining to characterize the matrix material.  相似文献   
17.
Inclusive neutron multiplicity distributions were measured by means of 4π liquid-scintillator detectors for Ar and Kr-induced reactions at 44 MeV/nucleon and 32 MeV/nucleon, respectively. For all the systems studied, the observed distributions exhibit a bump structure at large multiplicity, corresponding to highly dissipative collisions. For Ar-induced reactions, the excitation energies necessary to explain the most probable neutron multiplicity associated with these dissipative collisions are estimated, the correspondence between excitation energy and neutron multiplicity being calculated in the framework of the statistical model. The so-obtained values of excitation energies, which are systematically lower than those predicted using the massive-transfer picture, are discussed.  相似文献   
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The construction of relatively simple and inexpensive apparatus for the determination of the operating conditions for electrochemical detectors in high-pressure liquid chromatography systems is described. A procedure has been developed for the characterization of electrochemically active compounds.  相似文献   
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