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1.
We have studied the influence of surface fields H/sub p/ (generated by either direct or alternating core current) on soft magnetic properties of amorphous and nanocrystalline Fe/sub 73.5/Cu/sub 1/Nb/sub 3/Si/sub 15.5/B/sub 7/ ribbon. While in an amorphous ribbon the coercive field H/sub c/ decreases with H/sub p/, in the same optimally annealed ribbon (H/sub c/=1.3 A/m, M/sub m//spl ap/M/sub s/) H/sub c/ increases with H/sub p/ for all the explored types of H/sub p/ (static and dynamic with different phases with respect to that of the magnetizing field H). The unexpected increase of H/sub c/ in nanocrystalline ribbon is associated with the influence of H/sub p/ on the surface and main (inner) domain structure. Here, we develop a model that takes into account this influence and explains the experimental results. 相似文献
2.
Djordje Babic 《Circuits, Systems, and Signal Processing》2013,32(2):759-780
An efficient implementation for finding digitally the interpolated samples is the Farrow structure. It mimics digitally a hybrid system where a continuous-time (CT) signal is reconstructed using an analog reconstruction filter having a piecewise-polynomial impulse response. The interpolated samples are obtained by sampling reconstructed signal. This paper introduces a generalized design method for polynomial-based interpolation filters and Farrow structure. The proposed method also can be used to calculate the coefficients of Selva interpolator. In this approach, the ideal CT impulse response is truncated by using CT window functions. The obtained windowed impulse response is then approximated using the piecewise Taylor polynomial approximation. Length of the impulse response and degree of the approximating polynomial can be arbitrarily selected, and in this way the transition band width can be controlled. However, if CT fixed-window functions are used, the stopband attenuation is determined by window type and remains approximately constant with increase of length and order of the impulse response. The stopband attenuation can be controlled by using CT dynamic windows such as Kaiser window. The presented windowing design method is an effective tool for calculation of the Farrow structure coefficients, with filter performance that is comparable to the frequency domain design. 相似文献
3.
The authors derive an analytical formula for the change of propagation delay and phase penetration depth of a quarter-wave distributed Bragg reflector (DBR) owing to thickness and/or composition variations. The analytical expression provides a very good estimate of change in penetration depth with arbitrary thickness perturbation in one or more layers of the DBR. For a Fabry-Perot cavity clad on both sides by two quarter-wave DBRs, the shift in the Fabry-Perot mode due to thickness variations in one or both of the DBRs can be simply obtained by calculation using the change in penetration depths of the corresponding DBR or both DBRs 相似文献
4.
A notion of planar rearrangement of fullerenes is proposed as a general framework for all conceivable rearrangements of fullerenes satisfying a minimum physicochemical condition. The planar rearrangement is defined as an edge relocation such that the planarity of a given Schlegel diagram remains undisturbed. Graph-theoretical properties of planar rearrangements are discussed and characteristics for establishing a hierarchy between them are pointed out. A number of graph-theoretical concepts have been introduced to provide means for classification and systematic generation of fullerene rearrangements. The simpliest nontrivial rearrangements is shown to be the Stone-Wales rearrangement. 相似文献
5.
The Test Working Group of the ATM Forum is developing a specification for performance testing of ATM switches and networks. The emphasis is on the user-perceived frame-level performance. This article explains what is different about this new effort and describes its status 相似文献
6.
Up to now, C–V profiling through isotype heterojunctions has been performed assuming a uniform dielectric permittivity throughout the heterostructure. We extend the interpretation of C–V data to the case of a semiconductor with position-dependent dielectric permittivity, and we show that the variation of the dielectric permittivity across an isotype heterojunction interface has no effect on the determination of the heterojunction band discontinuity and the interface charge density. 相似文献
7.
8.
The present investigation deals with the effect of Al2O3 particle reinforcement on the lubricated sliding behavior of ZA-27 alloy. The composites with 3, 5, and 10 wt% of Al2O3 particles were produced by the compocasting procedure. Tribological properties of alloy and composites were studied, using
block-on-disk tribometer at different specific loads and sliding speeds. The test results revealed that composite specimens
exhibited significantly lower wear rate, but higher coefficient of friction than the matrix alloy specimens in all the combinations
of applied loads and sliding speeds. The improved antiwear characteristics of the composites were influenced by positive effects
of higher frictional heating on compatibility of the composite phases and suppressing micro-cracking tendency. Due to that,
effects of reinforcing hard particles were manifested through the reduced wear rate of composites, especially in conditions
of higher load, lower sliding speeds and higher Al2O3 particle content. In present wear tests, the significant forming of mechanically mixed layers was not noticed, what is confirmed
by the SEM microphotographs. 相似文献
9.
I-Hsing Tan Dudley J.J. Babic D.I. Cohen D.A. Young B.D. Hu E.L. Bowers J.E. Miller B.I. Koren U. Young M.G. 《Photonics Technology Letters, IEEE》1994,6(7):811-813
We demonstrate greater than 90% quantum efficiency in an In0.53Ga0.47As photodetector with a thin (900 Å) absorbing layer. This was achieved by inserting the In0.53 Ga0.47As/InP epitaxial layer into a microcavity composed of a GaAs/AlAs quarter-wavelength stack (QWS) and a Si/SiO2 dielectric mirror. The 900-Å-thick In0.53 Ga0.47As layer was wafer fused to a GaAs/AlAs mirror, having nearly 100% power reflectivity. A Si/SiO2 dielectric mirror was subsequently deposited onto the wafer-fused photodiode to form an asymmetric Fabry-Perot cavity. The external quantum efficiency and absorption bandwidth for the wafer-fused RCE photodiodes were measured to be 94±3% and 14 nm, respectively. To our knowledge, these wafer-fused RCE photodetectors have the highest external quantum efficiency and narrowest absorption bandwidth ever reported on the long-wavelength resonant-cavity-enhanced photodetectors 相似文献
10.