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181.
Four parameters are defined to measure the performance of a teletext system, namely, the probability of delivering a message within specified time, the transmission efficiency, the average number of errors per page, and the throughput. Each of them is derived and computational results are presented taking the UK teletext system as an example. These parameters are compared in their ability to characterize the performance of the teletext system 相似文献
182.
Bouferrache B. Krim G. Mejdoub N. Quanjer P.H. Freville M. Libert J.P. 《IEEE transactions on bio-medical engineering》1998,45(11):1305-1312
Dynamic modeling of lung C18O diffusion is used to measure the C18O transfer factor (TLco) of 14 newborns aged 1-4 mo. The model equation is based on the alveolar fractions of C18O and on changing alveolar ventilation induced by the rebreathing conditions. The model does not involve the volume of the rebreathing bag which is usually needed when applying rebreathing technique add which is a source of error. The equation is discretized and solved for recorded data obtained with equipment adapted to use in newborns. A least-square parameter calculation technique is applied to estimate TLco. Results show a strong relationship between this index and the biometrical ones and confirm those found in the literature featuring that the measurement duration can be considerably shortened 相似文献
183.
This work is devoted to the numerical solution of the Navier–Stokes equations for compressible viscous fluids. Finite element approximations and stabilization techniques are addressed. We present methods to implement discontinuous approximations for the pressure and the density. An upwinding methodology is being investigated which combines the ideas behind the stream line Petrov–Galerkin method and the flux limiter methods aiming to introduce numerical diffusion only where it is necessary. 相似文献
184.
The loss performance of tagged and normal ATM cells at a first-in-first-out (FIFO) buffer is studied. The authors show that if a partial buffer sharing mechanism is adopted the loss probability of normal cells can be firmly guaranteed, regardless of the traffic intensity of tagged cells 相似文献
185.
Saito M. Yoshitomi T. Hara H. Ono M. Akasaka Y. Nii H. Matsuda S. Momose H.S. Katsumata Y. Ushiku Y. Iwai H. 《Electron Devices, IEEE Transactions on》1993,40(12):2264-2272
A p-MOSFET structure with solid-phase diffused drain (SPDD) is proposed for future 0.1-μm and sub-0.1-μm devices. Highly doped ultrashallow p+ source and drain junctions have been obtained by solid-phase diffusion from a highly doped borosilicate glass (BSG) sidewall. The resulting shallow, high-concentration drain profile significantly improves short channel effects without increasing parasitic resistance. At the same time, an in situ highly-boron-doped LPCVD polysilicon gate is introduced to prevent the transconductance degradation which arises in ultrasmall p-MOSFETs with lower process temperature as a result of depletion formation in the p+-polysilicon gate. Excellent electrical characteristics and good hot-carrier reliability are achieved 相似文献
186.
This paper describes a fully integrated digital-spread spectrum transceiver chip fabricated through MOSIS in 1.2 μm CMOS. It includes a baseband spread spectrum transmitter and a coherent intermediate frequency (IF) receiver consisting of a Costas loop, an acquisition loop for the pseudo-noise (PN) sequence, and a clock recovery loop with a 406.4 MHz onchip numerically controlled oscillator (NCO). The transceiver is capable of operating at a maximum IF sampling rate of 50.8 MS/s and a maximum chip rate of 12.7 R Mchips/s (Mcps) with selectable data rates of 100, 200, 400, and 800 kbps. At the maximum operating speed of 50.8 R MS/s, it dissipates 1.1 W. In an additive white Gaussian noise channel the IF receiver achieves a receiver output SNR within 1 dB of theory and can acquire code with a wide range of input SNR from -17 dB to over 30 dB. The transceiver chip has been interfaced to an RF up/down converter to demonstrate a wireless voice/data/video link operating in the 902-928 MHz band 相似文献
187.
A novel method is presented for designing FIR linear phase filters with discrete coefficients using Hopfield neural networks. The proposed procedure is based on the minimisation of the energy function of the Hopfield neural network, and can produce a good solution to the design of FIR linear phase filters with discrete coefficients 相似文献
188.
The GaSb layers investigated were grown directly on GaAs substrates by molecular beam epitaxy (MBE) using SnTe source as the
n-type dopant. By using admittance spectroscopy, a dominant deep level with the activation energy of 0.23-0.26 eV was observed
and its concentration was affected by the Sb4/Ga flux ratio in the MBE growth. A lowest deep-level concentration together with a highest mobility was obtained for GaSb
grown at 550°C under a Sb4/Ga beam equivalent pressure (BEP) ratio around 7, which should correspond to the lowest ratio to maintain a Sb-stabilized
surface reconstruction. In the Hall measurement, an analysis of the temperature-dependent mobility shows that the ionized
impurity concentration increases proportionally with the sample’s donor concentration, suggesting that the ionized impurity
was introduced by an SnTe source. In addition, optical properties of an undoped p-, a lightly and heavily SnTe-doped GaSb
layers were studied by comparing their photoluminescence spectra at 4.5K. 相似文献
189.
Dynamic Programming (DP) applies to many signal and image processing applications including boundary following, the Viterbi algorithm, dynamic time warping, etc. This paper presents an array processor implementation of generic dynamic programming. Our architecture is a SIMD array attached to a host computer. The processing element of the architecture is based on an ASIC design opting for maximum speed-up. By adopting a torus interconnection network, a dual buffer structure, and a multilevel pipeline, the performance of the DP chip is expected to reach the order of several GOPS. The paper discusses both the dedicated hardware design and the data flow control of the DP chip and the total array.This work was supported in part by the NATO, Scientific and Environmental Affairs Division, Collaborative Research Grant SA.5-2-05(CRG.960201)424/96/JARC-501. 相似文献
190.
We study a generalization of the notion of the chromatic number of a graph in which the colors assigned to adjacent vertices are required to be, in a certain sense, far apart. © 1993 John Wiley & Sons, Inc. 相似文献