A backscattering model for ocean surface

A surface scattering model based on an approximate solution of the integral equations for the surface tangential fields has been developed for non-Gaussian distributed, finitely conducting surfaces. It consists of two parts. One part is proportional to the surface roughness spectrum, and the other to the surface bispectrum. The bispectrum part comes into the model when the third-order surface statistics are included. While the second-order statistics account for the wind directional dependence, the third-order statistics account for the dependence on the sense of direction of the wind. Thus, it is the critical part for explaining the difference between upwind and downwind observations. In general, the bispectrum is a complex quantity and the asymmetric effect of the sea surface is represented by its imaginary part. The model characteristics, such as polarization and azimuthal dependence, are illustrated through numerical calculations. The predictions of the model are compared with field measurements, and excellent agreement is obtained     

Amplitude dependence of frequency in oscillators

The lower part of the f.m. spectrum in oscillators is discussed and experimental results at 36 GHz are compared with Edson's theory. The discrepancy found is explained by Blaquière's frequency-amplitude dependence, and the parameter involved in this dependence is evaluated by equating experimental and theoretical linewidths. The signal-power spectrum is also presented.     

Schottky Barrier Impedance Measurements at UHF (Short Papers)

The observed frequency dependence of the real part of the small signal impedance of Schottky barrier varactor diodes has previously been explained via physical phenomena. A detailed experimental investigation shows that the frequency dependence is due to inevitable systematic errors in the measurement procedure used.     

Monte Carlo calculation of the drift velocity of electrons in n-GaAs

The drift velocity of electrons in n-GaAs has been calculated by a Monte Carlo technique for a nonparabolic central valley including the wave-vector dependence of the cell-periodic part of the Bloch functions in the     

Electrical properties of MnIn2Se4

Semiconductors - The temperature dependence of conductivity and current-voltage characteristics of MnIn2Se4 crystals have been studied. It is shown that the current in the nonlinear part of the...     

超标量微处理器研究与应用

首先介绍了超标量体系结构的基础，深入研究了超标量体系结构的基本特点和性能分析，详细地探讨了超标量体系中遇到的数据相关和结构相关的问题以及解决相关问题的Tomasulo算法及计分牌算法。在文章的最后，简单的讨论了动态转移预测和重排序缓冲机制。     

Modified theory of MISS,MIST and OMIST devices

The theory of MISS, MIST and OMIST devices are modified in order to get better fit with experimental data. Taking into account the generation current in the surface depletion layer and the voltage dependence of the neutral part of the base, the effect of temperature upon the threshold voltage is calculated explaining both a weak increasing and a strong decreasing dependence of it. Surface states, inhomogeneous tunnel oxide thickness and two-dimensional effects are also taken into account, resulting is significantly increased holding currents and decreased sensitivity of the device to gate currents.     

Simulation and modeling of the low-frequency base resistance ofbipolar transistors and its dependence on current and geometry

The current and geometry dependence of the low-frequency base resistance of high-speed bipolar transistors was investigated by means of quasi-three-dimensional numerical device simulations. It is shown that the total base resistance can be separated into a current- and geometry-dependent internal part and an only geometry-dependent external part. Both of these parts can be accurately approximated by simple analytical formulas which are well suited for compact transistor modeling. The investigations are based on sheet resistances and dimensions the values of which are typical for self-aligned double-polysilicon technology     

A Unified Finite-Element Solution From Zero Frequency to Microwave Frequencies for Full-Wave Modeling of Large-Scale Three-Dimensional On-Chip Interconnect Structures

It has been observed that a full-wave finite-element-based solution breaks down at low frequencies. This hinders its application to on-chip problems in which broadband modeling from direct current to microwave frequencies is required. Although a static formulation and a full-wave formulation can be stitched together to solve this problem, it is cumbersome to implement both static and full-wave solvers and make transitions between these two when necessary. In this work, a unified finite-element solution from zero frequency to microwave frequencies is developed for full-wave modeling of large-scale three-dimensional on-chip interconnect structures. In this solution, a single full-wave formulation is used. No switching to a static formulation is needed at low frequencies. This is achieved by first identifying the reason why a full-wave eigenvalue-based solution breaks down at low frequencies, and then developing an approach to eliminate the reason. The low frequency breakdown problem was found to be attributed to the discrepant frequency dependence of the real part and the imaginary part of the eigenvalues, which leads to an ill-conditioned eigenvalue system at low frequencies. The discrepant frequency dependence of the real part and the imaginary part is further attributed to the different scaling of the transverse and longitudinal fields with respect to frequency in a transmission-line type structure. By extracting transverse and longitudinal fields separately in the framework of a full-wave formulation, we avoid the numerical difficulty of solving an ill-conditioned eigen-system at low frequencies. The validity of the proposed approach is demonstrated by numerical and experimental results.      

Vibration modes and electron-phonon interaction in semiconductor nanotubes

Vibration eigenmodes of a III-V semiconductor nanotube are found taking into account the crystal structure and piezoelectric effect. Electron-phonon interaction is studied, and it is shown that, in contrast to bulk samples, its piezoelectric part has a complicated dependence on the phonon frequency.     

A KIND OF HYBRID LANGUAGE MODEL EMPLOYED IN POST PROCESSING OF CHINESE SPEECH RECOGNITION

A kind of Chinese combined language model, that takes into account POS(part of speech) information in a trigram-based statistical language model, is presented in the paper. The theoretical analysis and experiments all show that the model not only is lower than trigram model in PP(perplexity), but also is superior to trigram model in dependence on testing text domain.     

Frequency Dependence of the Conductivity of Disordered Semiconductors in the Region of the Transition to the Fixed-Range Hopping Regime

The effect of hybridization of electron states on the high-frequency conductivity of disordered semiconductors is studied. It is shown that the dependence of the pre-exponential factor of the resonance integral on the intercenter separation in a pair determines the abruptness of the change in conductivity mechanisms near the transition of the frequency dependence of the real part of the conductivity σ₁(ω) from sublinear to quadratic. The abruptness of the change of the conductivity regimes is associated with a rapid decrease in hopping distance with increasing frequency near the transition, which leads to a substantial relative decrease in the contribution from the phononless conductivity component in the variable-range hopping regime with increasing frequency and transition to the fixed-range hopping conductivity regime.     

On the high-frequency characteristics of substrate resistance in RF MOSFETs

The high-frequency (HF) behavior of substrate components in MOSFETs is studied at different bias conditions for a 0.35 /spl mu/m BICMOS technology in the frequency range up to 10 GHz. It was found that the observed strong bias dependence of the real part of admittance y/sub 22/, Re{y/sub 22/}, is mainly contributed by the channel conductance. A very weak bias dependence of substrate resistance was found after deembedding the measured y/sub 22/ to remove the influence of channel resistance R/sub ds/ and gate-to-drain capacitance C/sub gd/. The results are key to the understanding and modeling of the HF behavior of MOSFET substrate components for RF IC design.     

Temperature dependence of gate and substrate currents in the CHEcrossover regime

This paper presents new experimental data on the bias and temperature dependence of gate (I_G) and substrate (I_B ) currents in submicrometer n-MOSFET's at drain voltages much smaller than the Si-SiO₂ energy barrier (V_DS≪Φ_B/q≃3.15 V). In particular, we report simultaneous measurements of I_G and I_B in that part of the bias range conventionally defined “channel hot electron” regime (CHE) where I_B decreases for decreasing temperature (substrate current crossover regime). It is found that, at low V_DS, the two currents exhibit an opposite temperature dependence, unexplained by present models     

On the optimality of linear schedules

An algorithm can be modeled as a set of indexed computations, and a schedule is a mapping of the algorithm index space into time.Linear schedules are a special class of schedules that are described by a linear mapping and are commonly used in many systolic algorithms.Free schedules cause computations of an algorithm to execute as soon as their operands are available. If one computation uses data generated by another computation, then a data dependence exists between these two computations which can be represented by the difference of their indices (calleddependence vector). Many important algorithms are characterized by the fact that data dependencies areuniform, i.e., the values of the dependence vectors are independent of the indices of computations. There are applications where it is of interest to find an optimal linear schedule with respect to the time of execution ofa specific computation of the given algorithm. This paper addresses the problem of identifying optimal linear schedules for uniform dependence algorithms so that the execution time ofa specific computation of the algorithm is minimized and proposes a procedure to solve this problem based on the mathematical solution of a linear optimization problem. Also, linear schedules are compared with free schedules. The comparison indicates that optimal linear schedules can be as efficient as free schedules, the best schedules possible, and identifies a class of algorithms for which this is always true. This research was supported in part by the National Science Foundation under Grant DCI-8419745 and in part by the Innovative Science and Technology Office of the Strategic Defense Initiative Organization and was administered through the Office of Naval Research under contracts No. 00014-85-k-0588 and No. 00014-88-k-0723.     

Improved Si piezo-transistors for mechano-electrical transducers

Piezo-transistors with stresses applied to the emitter region by means of small hard styli for application as mechano-electric transducers have been improved. High signal-to-noise ratios were obtained in gold-doped n-p-n Si planar transistors. New designs for emitter electrodes have been devised which make the fabrication of the transducer units easy. Rather large stressing areas (60-µm diameter) which are surrounded by ring-type emitter electrodes with overlay bonding pads are provided in the central part of the emitter region (90-µm diameter). Signal-to-noise ratios are high and independent of the position of the stylus over the stressing area. By using these transistors mechano-electrical transducer units were fabricated with higher stabilities. It was found that noise decreases with increasing stress. Life-test results of the transducer units are also indicated. The stress dependence of transistors were explained by the combined effects of the stress dependence of the emitter efficiency and the stress dependence of the base transport factor. Gold-doping seemed to enhance the stress dependence of the base transport factor due to a very short minority carrier lifetime.     

Effect of bit-to-bit dependence on packet error rate using asynchronous DS-CDMA for mobile packet radio networks

The probability of packet success for asynchronous direct sequence code division multiple access (DS-CDMA) over the multipath fading channel is investigated under different fading conditions and for different cases. We studied the bit-to-bit dependence caused by the multipath fading and by the multiple access interference (MAI) originating from the chip and phase offsets between the desired and interfering signals. We investigated the effect of using the Gaussian versus the improved Gaussian process on the computation of probability of packet success as well as the effect of the bit-to-bit dependence within a packet. The improved Gaussian approximation provides more accurate values for the probability of bit error for any number of simultaneous users, while it also allows us to incorporate the effects of bit-to-bit dependence into the calculations of the probability of packet success.This paper was presented in part at the 17th Biennial Symposium on Communiations, Kingston, June 1994. This work was supported by a strategic grant (STR-0100720) from the Natural Sciences and Engineering Research Council (NSERC) of Canada.     

Quantifying cognitive state from EEG using dependence measures

The exquisite human ability to perceive facial features has been explained by the activity of neurons particularly responsive to faces, found in the fusiform gyrus and the anterior part of the superior temporal sulcus. This study hypothesizes and demonstrates that it is possible to automatically discriminate face processing from processing of a simple control stimulus based on processed EEGs in an online fashion with high temporal resolution using measures of statistical dependence applied on steady-state visual evoked potentials. Correlation, mutual information, and a novel measure of association, referred to as generalized measure of association (GMA), were applied on filtered current source density data. Dependences between channel locations were assessed for two separate conditions elicited by distinct pictures (a face and a Gabor grating) flickering at a rate of 17.5?Hz. Filter settings were chosen to minimize the distortion produced by bandpassing parameters on dependence estimation. Statistical analysis was performed for automated stimulus classification using the Kolmogorov-Smirnov test. Results show active regions in the occipito-parietal part of the brain for both conditions with a greater dependence between occipital and inferotemporal sites for the face stimulus. GMA achieved a higher performance in discriminating the two conditions. Because no additional face-like stimuli were examined, this study established a basic difference between one particular face and one nonface stimulus. Future work may use additional stimuli and experimental manipulations to determine the specificity of the current connectivity results.     

Comment on `Numerical check on the accuracy of spherical-wave expansions?

A convergence criterion for the Laurent spherical-wave expansion is discussed, with particular emphasis on its dependence on the nature of the radiating source. Both an inappropriate choice of truncation point of the series and of the integration surface for the determination of the spherical-wave coefficients may introduce errors in near-field antenna calculations. However, a procedure is outlined which ensures that an accuracy of the order of one part in 105 is achieved.     

Josephson admittance spectroscopy of log-periodic antenna at the submillimeter wavelength range

Application of Josephson admittance spectroscopy for the spectral analysis of a broad-band log-periodic antenna was demonstrated at the frequency range from 50 to 700 GHz. A real part of the antenna admittance was reconstructed as a function of the frequency, when the antenna was connected to a Josephson junction. Small-scale features were observed on this dependence. They demonstrated a periodicity in the logarithmic frequency scale and were related to the antenna resonances.