一种基于路由扩散的大规模网络控管方法

针对已有的网络控管方法的缺点,提出一种基于路由扩散的大规模网络控管的新方法。阐述了其基本网络拓扑结构、动态路由协议的选取和配置等问题,并同已有的方法进行了详细对比。该方法具有路由器负担小、控制规则容量大、智能化、可扩展以及一处配置多处生效等优点,适用于大规模网络控管。     

A model of high-and low-temperature phosphorus diffusion in silicon by a dual pair mechanism

A model of phosphorus diffusion in silicon was developed on the basis of a dual pair mechanism; according to this model, the contribution of the impurity-vacancy (PV) and impurity-self-interstitial (PI) pairs to diffusion is accounted for directly in terms of the phosphorus diffusion coefficient. A violation of thermodynamic equilibrium in relation to native point defects occurs as a result of diffusion of the PI neutral pairs. At the high-temperature diffusion stage, the phosphorus diffusion is described by a single diffusion equation with the diffusion coefficient dependent on both the local and surface phosphorus concentrations; whereas at the next (occurring at lower temperatures) stage, the phosphorus diffusion is described by two diffusion equations for the total concentrations of the components containing phosphorus and self-interstitials. An anomalously high rate of the low-temperature diffusion is ensured by excess self-interstitials accumulated in the doped layer during the preceding high-temperature diffusion. The model makes it possible to quantitatively account for the special features of the phosphorus diffusion in a wide range of the surface concentrations at both the high (900–1100°C) and lower (500–700°C) temperatures.     

Shallow phosphorus diffusion profiles in silicon

Concentration profiles have been determined for phosphorus diffusion into silicon. These have been fitted to the solution of Fick's diffusion equations using a model where a moving boundary separates two distinct phases. Thus, it is concluded that the silicon surface region is part of a different phase from the rest of the diffused layer. For the short diffusion times studied, the phase boundary reaction is the rate limiting process and the phase boundary moves at a nearly constant rate. In the region beyond the phase boundary the transport of phosphorus is controlled by two diffusion species, characterized by two substantially different diffusion coefficients. The slow diffusant is present mainly in a transition region between the phase boundary and the fast diffusant dominated region. The fast diffusant has a maximum concentration at the phase boundary. The linear rates of movement of the phase boundary, the concentrations of the fast diffusant at the phase boundary, and the diffusion constants for the slow and the fast diffusants were obtained over the temperature range from 820 to 1100°C. As the diffusion temperature increases the diffusion constants for the slow and the fast diffusants approach each other. At 1100°C, the diffusion profile can be represented by a single diffusion constant. For long diffusion times the phase boundary became less distinct.     

A spectral Lanczos decomposition method for solving 3-Dlow-frequency electromagnetic diffusion by the finite-elementmethod

A very efficient three-dimensional (3-D) solver for the diffusion of the electromagnetic fields in an inhomogeneous medium is described. The proposed method employs either the node-based or the edge-based finite-element method (FEM) to discretize Maxwell's equations. The resultant matrix equation is solved by the spectral Lanczos decomposition method (SLDM), which is based on the Krylov subspace (Lanczos) approximation of the solution in the frequency domain. By analyzing some practical geophysical problems, it is shown that the SLDM is extremely fast and, furthermore, the electromagnetic fields at many frequencies can be evaluated by performing the SLDM iteration only at the lowest frequency     

Lifetime control by palladium diffusion in silicon

This paper will discuss the use of palladium for the control of lifetime in silicon power devices. It is shown that palladium has the advantage over platinum of lower solid solubility (by a factor of 20–50). As a result, greater process control can be achieved for lifetimes in the range that is desirable for power rectifiers and thyristors (0.1–1 μsec). Experiments, conducted on diodes made with both p- and n-type silicon, are used to establish the dominant lifetime controlling level in each case, together with its capture parameters. Finally, an assessment is made of the advantages and disadvantages of palladium doping for semiconductor power devices.     

一种新的扩散混合机制

本文针对扩散混合新机制扩压函数，提出了它的基本设计原则。引入了级连布尔函数的概念，给出并证明了它的一些性质，在此基础上提出了单比特扩压函数的一种构造方法，并给出了一个具体的具有良好密码学性能且结构简单易于软硬件实现的单比特扩压函数实例。     

A direct control method for matrix converters

Until now, direct control methods have been mainly investigated and used in conjunction with voltage source converters. In this paper, the authors develop a direct current control method for matrix converters. There are two objectives for the direct current control: the desired current has to be impressed into the load, and the current, drawn from the mains, should be in phase with the voltage and should be (nearly) sinusoidal. This implies active damping of the 400 Hz resonance or the line filter. The method is implemented on a DSP and tested on a 10 kVA matrix converter     

一种柔性曲柄滑块机构的解耦控制方法

基于对柔性机构运动学和动力学模型的分析与解耦,提出一种解耦控制方法。这种方法有效地利用了模型信息,将反馈划分为由刚性和柔性运动两路反馈,通过两组不同的控制器分别计算各自的输出量,并在控制器输出端叠加输出。针对曲柄滑块机构进行柔性动力学建模并实施了轨迹跟踪仿真。与同样基于动力学模型的计算力矩法进行了对比,结果证明本方法的可行性和高效性。     

A passivity-based method for induction motor control

The control of an induction motor is a difficult problem, since the dynamics of the induction motor are nonlinear, the rotor electrical state variables (i.e., rotor fluxes or currents) are usually unavailable for measurement, and the motor parameters can vary significantly from their nominal values. The main purpose of this paper is to develop a control algorithm that forces the induction motor to track time-varying speed, position, and flux trajectories without knowledge of the rotor electrical state variables. To achieve this, a passivity-based method is developed. The key point with this method is the identification of terms, known as workless forces, which appear in the dynamic equations of the induction motor but do not have any effect on the energy balance equation of the induction motor. These terms do not influence the stability properties of the induction motor and, hence, there is no need to cancel them with feedback control. This leads to a simpler control structure and enhances the robustness of the control system. Experimental results show that the passivity-based method provides close tracking of time-varying speed, position, and flux trajectories without knowledge of the rotor electrical state variables     

A new method for computing nonlinear carrier diffusion insemiconductor optical devices

The solution of carrier diffusion equations typically associated with semiconductor optical devices has been achieved by combining a function expansion scheme, using the Hermite-Gauss functions as the basis set, with the collocation numerical procedure. Results for a wide range of cases obtained by this new scheme compare very favorably with those calculated with other methods. Not only is the present process computationally fast and efficient, but it has the added attraction of providing the basis for conveniently solving also the nonlinear electromagnetic wave equation for the self-consistent modeling of such devices     

On phosphorus diffusion in silicon under oxidizing atmospheres

Phosphorus diffusion in silicon has been carried out in both inert (nitrogen) and oxidizing (90% nitrogen plus 10% oxygen, dry oxygen, steam) atmospheres, over a wide temperature range (1000–1200°C) and for doping concentrations usually encountered in the silicon planar technology. The experimental data, interpreted on the basis of the Kato and Nishi theoretical model taking into account the redistribution phenomena at the moving oxide-silicon interface, show that the phosphorous diffusion coefficient is strongly influenced by the nature of the ambient atmosphere in which the diffusion is carried out. Two different values for the activation energy of the diffusion process, E_i = 3·5 eV for the inert and E₀ = 2·5 eV for the oxidizing conditions, have been found. These values seem to confirm the phosphorous diffusion mechanism based on E-centers for the inert case, while for the oxidizing case a different diffusion mechanism should be considered.     

Silicon dioxide masking of phosphorus diffusion in silicon

Doped oxide diffusion condition was used to diffuse P-32 radioisotope into 1100°C thermal SiO₂. Two phosphorus containing diffusing species were identified. Their diffusion characteristics were used with the literature data on the kinetics of phosphosilicate glass formation to construct a multiple-zone model of P₂O₅ diffusion into thermal SiO₂. This physical model was quantitatively verified by several types of masking experiments. In addition, the effects of dry-wet and dry-wet-dry oxidations (at 1100 and 1200°C) on the masking capability of the thermal oxides were examined.     

Silicon nitride as a mask in phosphorus diffusion

By means of tracer and activation experiments it is shown that during phosphorus diffusion in silicon nitride diffusion profiles are produced, which are very similar to the profiles in silicon dioxide processed in the same experiment. When oxygen was used as part of the carrier gas as is customary in semiconductor technology, a glass was produced in both cases which consisted of SiO₂ and P₂O₅ and whose identity was proved by i.r. absorption and determination of the refractive index. When the medium does not contain oxygen, part of the nitride is transformed to silicon phosphide which is incorporated in the glass or escapes at higher temperatures. When oxygen is present, the silicon phosphide occurs briefly in an intermediate reaction. In this way the normal, slow oxidation of the nitride is accelerated and phosphorus pentoxide acts as a catalyst. The analogous formation of glass from oxide and nitride is the reason why silicon nitride exhibits a similar masking effect as silicon dioxide in phosphorus diffusion, even though it masks better than silicon dioxide against the diffusion of a number of other elements.     

Concentration-dependent diffusion of boron and phosphorus in silicon

A calculation is made of the tail of the impurity concentration profile resulting from concentration-dependent diffusion from a constant surface concentration into a semi-infinite medium. The calculation predicts that if the concentration dependence at low impurity concentrations is negligible, the low concentration portion of the doping profile should still take the familiar form,C = C'_{s} erfc (x/2 D_{i^{frac{1}{2}}}t^{frac{1}{2}}). Diis the commonly known diffusion coefficient at low impurity concentrations, whileC'_{s}is the "apparent" surface concentration.C'_{s}depends on the actual surface concentration and also depends on how the diffusion coefficient varies with impurity concentration at high concentrations. It is a constant for a given diffusion system but could be orders of magnitude higher than the actual surface concentration. Empirical data have been obtained for boron and phosphorus diffusions in silicon and found to be in good agreement with this prediction.     

Double-step annealing and ambient effects on phosphorus implanted emitters in silicon

Emitters of npn silicon bipolar transistors have been made by a phosphorus implantation at 50 keV P⁺ to a dose of 1×10¹⁶ cm^?2. This was followed by high temperature processes to reduce lattice disorder, to drive-in the phosphorus atoms, and to form oxide layers. The first process step was carried out by using single- and double-step anneals in various ambients (dry N₂, dry O₂ and steam) while the drive-in and oxidation steps were common for all structures. Electrical measurements on emitter/base leakage current, low frequency (popcorn) noise and current gain showed that the annealing ambient had a major influence. The transistors with implanted emitters annealed in a dry N₂ ambient are comparable to commercial ones with thermally-diffused emitters. TEM observations on samples annealed in steam ambients revealed dislocatons extending into the sidewall of the emitter/base junction. This sidewall penetration of dislocations is the main origin of the degradation of the emitter/base junction characteristics.     

Approximations to two-step diffusion process by Prony's method

A simple two-term approximation that is accurate over a wide range of drive-in ratios is given for the two-step diffusion process. Comparison with earlier approximations are graphically given. The final approximation is simple and convenient in evaluating the device performance. The Prony's method adopted to approximate erfc(x) is useful in approximating other profiles as well, such as anomalous diffusion profile of phosphorus, ion-implanted profile, etc.     

A method for suppressing torque ripple of an AC motor by currentamplitude control

The authors examine a thyristor motor torque ripple suppression method that is simple in configuration. A simplified method of calculating motor torque ripple is introduced. This method enables calculation of velocity fluctuation due to torque ripple in the vicinity of the resonant frequency. Calculation results show that operation around the resonant frequency constitutes a problem. The current amplitude control method is effective for suppressing the torque ripple at the resonant frequency. This method detects the velocity fluctuation component and controls the current amplitude to eliminate that component. The velocity fluctuation component is detectable by using a filter that has a differential element. In addition, it is shown that the characteristic of the control system can be calculated with the aid of a Bode diagram, and its effectiveness is confirmed through simulation. From simulation results, this suppression method is found to be effective in reducing the velocity fluctuation to a practical level     

一种智能手机获取监测环境温度、湿度的实现方法

本文介绍一种利用智能手机耳机接口音频传输,来实现智能手机拓展监测环境温度、湿度的应用设计与实现方案,同时提出了可兼容2种不同耳机接口标准的解决方案,增强了智能手机拓展应用价值。本文网络版地址：http：//www.eepw.com.cn/article/274760.htm     

Adaptive error diffusion method for image quantisation

An adaptive error diffusion method for image quantisation is presented. The error filter coefficients are adapted using a generalised two-dimensional LMS algorithm and the quantisation scale is calculated on the basis of the image histogram. The developed method provides a minimum reconstruction error, a decrease in false contours in the homogeneous areas and precise reproduction of the edges in the output image.<>     

The kinetics of open tube phosphorus diffusion in silicon

Using a novel liquid-phase dilution technique, open-tube diffusion of radiophosphorus into silicon was carried out for the first time under intrinsic oxide non-accumulation conditions. The existence of the surface-barrier rate control of the deposition process in the open-tube technique was established from the concentration profiles. An in-depth analysis of the vapor-solid partition coefficient of the phosphorus-silicon system showed the dramatic contribution of oxygen in the incorporation of phosphorus into silicon in the open-tube process. The fitted deposition and redistribution profiles of phosphorus in silicon supported the concept of equivalent diffusion kinetics in both the deposition and redistribution steps. The present study also supported the Kennedy-Murley redistribution kinetics model quantitatively.