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81.
A set of chaotic attractors is observed on a boost converter model. The union of their Poincare maps is strange. The attractors are densely packed such that they are sensitive to initial conditions. However every attractor in the set is stable with a finite (may be long) period 相似文献
82.
Lei Shan Meghelli M. Joong-Ho Kim Trewhella J.M. Oprysko M.M. 《Advanced Packaging, IEEE Transactions on》2002,25(2):248-254
A 50 Gb/s package for SiGe BiCMOS 4:1 multiplexer and 1:4 demultiplexer targeting SONET OC-768 serial communication systems is introduced in this work. The package was designed to facilitate bit-error-rate tests and constructed with high-speed coaxial connectors, transmission lines on ceramic substrate, ribbon bonds for chip-to-package interconnects, and a metal composite housing. Numerical simulations were conducted to guide the package design, and both small signal measurements and operational tests were performed thereafter to verify the design and modeling concepts. To keep the model structure under the existing computing capability, the simulation was segmented into three sections - coaxial connector to transmission line, transmission line alone, and transmission line to ribbon bond, and then the results were assembled to predict the performance of the entire package. The package was operated up to 50 Gb/s with low degradation to input digital waveforms and free of error. 相似文献
83.
同等功率和照射时间条件下,在14只家兔大脑皮质运用伊文思蓝染料和超微结构观察方法进行血脑屏障改变的研究。结果表明:CO_2激光作用十分表浅,且激光作用后的水肿层血脑屏障改变是可逆的。 相似文献
84.
用614.3nm染料激光照射以Ne为缓冲气体的Ca空心阴极灯,观察到了Ca原子的Pen-ning离化效应。对比在Li空心阴极灯中获得的光电流信号,解释了Ca原子的彭宁离化。 相似文献
85.
Y. Yang B. F. Wang J. Xiong Y. Zeng Z. P. Chen X. Y. Yang 《Metallurgical and Materials Transactions A》2006,37(10):3131-3137
The microstructure and microtexture in adiabatic shear bands (ASBs) on the titanium side in the titanium/mild steel explosive
cladding interface are investigated by means of optical microscopy, scanning electron microscopy/electron backscattered diffraction
(SEM/EBSD), and transmission electron microscopy (TEM). Highly elongated subgrains and fine equiaxed grains with low dislocation
density are observed in the ASBs. Microtextures (25 deg, 75 deg, 0 deg), (70 deg, 45 deg, 0 deg), and (0 deg, 15 deg, 30 deg)
formed within the ASBs suggest the occurrence of the recrystallization. The grain boundaries within ASBs are geometrically
necessary boundaries (GNBs) with high angles. Finite element computations are performed to obtain the effective strain and
temperature distributions within the ASBs under the measured boundary conditions. The rotation dynamic recrystallization (RDR)
mechanism is employed to describe the kinetics of the nanograins’ formation and the recrystallized process within ASBs. During
the deformation time (about 5 to 10 μs), the following processes take place: dislocations accumulate to form elongated cell
structures, cell structures break up to form subgrains, and subgrains rotate and finally form recrystallized grains. The small
grains within ASBs are formed during the deformation and do not undergo significant growth by grain boundary migration after
deformation. 相似文献
86.
在本试验中,采用智能同步广播激励器和CCTV传输的1MHz标频,实现了中波同步广播同频保护率趋于0dB.并提出了自适应相位跟踪同步的概念。 相似文献
87.
Shye Lin Wu Chung Len Lee Tan Fu Lei Chen C.F. Chen L.J. Ho K.Z. Ling Y.C. 《Electron Device Letters, IEEE》1994,15(4):120-122
In this study, it is demonstrated that the incorporation of fluorine can enhance poly-Si/Si interfacial oxide break-up in the poly-Si emitter contacted p+-n shallow junction formation. The annealing temperature for breaking up the poly-Si/Si interfacial oxide has been found to be as low as 900°C. As a result, the junction depth of the BF2-implanted device is much larger than that of the boron-implanted device 相似文献
88.
Performance analysis of adaptive interleaving for OFDM systems 总被引:7,自引:0,他引:7
We proposed a novel interleaving technique for orthogonal frequency division multiplexing (OFDM), namely adaptive interleaving, which can break the bursty channel errors more effectively than traditional block interleaving. The technique rearranges the symbols according to instantaneous channel state information of the OFDM subcarriers so as to reduce or minimize the bit error rate (BER) of each OFDM frame. It is well suited to OFDM systems because the channel state information (CSI) values of the whole frame could be estimated at once when transmitted symbols are framed in the frequency dimension. Extensive simulations show that the proposed scheme can greatly improve the performance of the coded modulation systems utilizing block interleaving. Furthermore, we show that the adaptive interleaving out performs any other static interleaving schemes, even in the fast fading channel (with independent fading between symbols). We derived a semi-analytical bound for the BER of the adaptive interleaving scheme under correlated Rayleigh fading channels. Furthermore, we discussed the transmitter-receiver (interleaving pattern) synchronization problem 相似文献
89.
Pd-Ge based ohmic contact to n-GaAs with a TiW diffusion barrier was investigated. Electrical analysis as well as Auger electron
spectroscopy and the scanning electron microscopy were used to study the contact after it was subjected to different furnace
and rapid thermal annealing and different aging steps. All analyses show that TiW can act as a good barrier metal for the
Au/Ge/Pd/n-GaAs contact system. A value of 1.45 × 10−6 Ω-cm2 for the specific contact resistance was obtained for the Au/TiW/Ge/Pd/n-GaAs contact after it was rapid thermally annealed
at 425°C for 90 s. It can withstand a thermal aging at 350°C for 40 h with its ρc increasing to 2.94 × 10−6Ω-cm2 and for an aging at 410°C for 40 h with its ρc increasing to 1.38 × 10−5 Ω-cm2. 相似文献
90.