共查询到20条相似文献,搜索用时 140 毫秒
1.
2.
目前集约建模的趋势是由基于阈值电压的模型转向基于表面势的模型,而后者需要一个对非线性Pao-Sah电压方程的精确解,作为隐含数方程,Pao-Sah电压方程必须数值求解以求得表面势。牛顿算法是一个收敛较快而常用的算法,但却易收敛到错误的根,提出一个能保证牛顿算法收敛到正确的表面势解、且具有可控的高精度及运算速度的初始值,由该初始值计算并分析了数值计算结果。高精度的数值解可作为其它近似解的检验。 相似文献
3.
绝对值方程Ax-|x|=b,A∈Rn×n,b∈Rn是一类特殊的非线性方程,且是NP-Hard问题。文中根据其半光滑的特性,通过构造光滑逼近函数,提出了求解绝对值方程的光滑牛顿算法。理论分析表明方程有解,A的奇异值>1时,算法具有全局收敛性,收敛速度为二次,实验结果表明了该算法的可行性。最终在总结中提出了光滑牛顿法可供改进的地方。 相似文献
4.
5.
用数值方法对泊松方程求解时,往往要对迭代的中间结果作适当的压缩处理,以加快收敛速度和避免溢出。本文提出一种单一指数因子的非线性压缩法。一维数值模拟结果表明,平衡态时不必进行压缩处理。而在非平衡态时,最佳指数压缩因子的大小与杂质浓度有关。参考本文给出的数值计算结果,根据给定器件的杂质浓度分布,选定一最佳指数压缩因子,可以使泊松方程的数值求解过程具有最快的收敛速度。 相似文献
6.
薛舫时 《固体电子学研究与进展》2014,(6)
<正>3短栅长HFET在高漏压下的能带畸变在一般的异质结能带计算中,都只考虑异质结材料生长方向的势垒变化。现在表面电势在x方向产生很大的电场梯度,该表面电场会扩展到整个异质结内,形成复杂的二维电场分布。于是在自洽求解泊松方程和薛定谔方程时就必须求解二维泊松方程 相似文献
7.
AlGaN/GaN一维模型自洽求解和二维电子气特性研究 总被引:1,自引:1,他引:0
实现了一维Poisson-Schrodinger方程的自洽求解,在此基础上求出了AlGaN/GaN异质结导带结构和二维电子气分布。计算结果表明极化效应是形成高浓度电子面密度的主要因素。研究了AlGaN/GaN系统中隔离层厚度对二维电子气浓度的影响,并对计算结果进行了分析。 相似文献
8.
9.
《固体电子学研究与进展》2015,(1)
在忽略二维电子气波函数对势垒层渗透的前提下提出了直接求解无电子势垒层泊松方程来计算势垒层能带的新思路,提出了把势垒层以外的极化电荷、杂质电荷及电子电荷作为势垒层边界上的界面电荷来解势垒层泊松方程的新方法。由此计算出的势垒层能带和自洽能带计算结果相吻合。用电子气密度多项式来拟合沟道阱子带能级随电子气密度变化的曲线,推算出新的二维电子气密度的超越方程。对于各种不同异质结构,从超越方程解出的电子气密度和势垒层能带同自洽能带计算结果相吻合,从而创立了一种自洽求解沟道阱泊松方程和薛定谔方程的新方法。研究了二维电子气密度与势垒层异质结构的相互作用,讨论了电子气密度随异质结构的变化,提出了异质结能带剪裁的新思路。 相似文献
10.
11.
This paper presents a comparison of the following algorithms for accelerated determination of periodic steady state of switched networks: Newton's method with analytically determined Jacobian; Newton's method with numerically determined Jacobian; Newton's method with Broyden updates of an initial numerically determined Jacobian; Newton's method with a globally convergent strategy (and numerical Jacobian); Bukowski's method; and Skelboe's method. Each algorithm is incorporated into a very accurate power electronics' simulator (PECS) at source-code level and compared on a common basis. The results on several switching converters suggest the analytical Newton's method to be the most accurate and fastest. When analytical derivatives are not available, both Broyden's and Skelboe's methods are competitive. 相似文献
12.
《Proceedings of the IEEE. Institute of Electrical and Electronics Engineers》1967,55(11):1819-1826
A new iteration method for nonlinear dc analysis, based on Broyden's modification of the Newton-Raphson method, is described. Broyden introduces a variable correction factor which is chosen so as to minimize, or at least reduce, the size of the error vector at each iteration. This completely precludes divergence of the algorithm. Broyden also develops a means for updating the inverse Jacobian matrix without ever having to compute or invert it explicitly. Two algorithms are described, one for solving a single nonlinear problem and the other for solving a large number of neighboring problems such as are encountered in statistical (Monte Carlo) analysis. Timing measurements on these two algorithms are reported. Application of these algorithms to statistical ac analysis and to frequency response calculations is proposed and a possible method of improving the basic algorithm by means of a sparse matrix technique is described. 相似文献
13.
Sparse linear arrays provide better performance than the filled linear arrays in terms of direction estimation and resolution with reduced size and low cost. However, they are subject to manifold ambiguity. A method based on the Multiple Signal Classification (MUSIC) algorithm to solve the manifold ambiguity of uncorrelated sources for sparse array is proposed in this paper. The method consists of two steps. The first step is to obtain all the directions of arrivals (DOAs), including true and spurious DOAs, using traditional MUSIC. The second step is to estimate the power values of the all DOAs by substituting all the DOAs to a cost function. The well-known Davidson Fletcher Powell (DFP) and Broyden Fletcher Goldfarb Shanno (BFGS) algorithms are used to estimate the power values. The power values of spurious DOAs are very small or tend to zero compared with the values of the true DOAs. The true DOAs are then discriminated easily from the spurious DOAs with the power values. Simulation results demonstrate the effectiveness and the feasibility of the method. 相似文献
14.
15.
José María Cabero Ignacio Olabarrieta Sergio Gil-López Javier Del Ser José Luis Martín 《Wireless Networks》2014,20(8):2287-2305
Information about the position of entities is very valuable in many fields. People, animals, robots and sensors are some examples of entities that have been targeted as nodes of interest for localization purposes. Technical advances in ubiquitous computing and wireless communications properties are very valuable means to obtain localization information. This paper presents a novel range-free localization algorithm based on connectivity and motion (LACM). The core of the algorithm is an error function that measures the error of the obtained trajectories with respect to the localization solution space, a multi-dimensional space that encompasses all solutions that satisfy completely the constraints of a range-free localization problem. LACM is a centralized method that can be used standalone or as a refinement phase for other localization methods. Limited-memory Broyden–Fletcher–Goldfarb–Shanno, an unconstrained optimization algorithm, is the numerical method used to minimize the error function. The performance of LACM is validated both through extensive simulations with excellent results in scenarios with irregular communications and by transforming real Bluetooth connectivity traces into localization information. 相似文献
16.
《Selected Areas in Communications, IEEE Journal on》2006,24(8):1571-1580
This paper presents efficient multiuser margin optimization algorithms suitable for multicarrier digital subscriber line (DSL) systems using Dynamic Spectrum Management (DSM). The favorable monotonicity and fairness properties of multiuser margin are employed to formulate a box-constrained nonlinear least squares (NLSQ) problem for multiuser margin maximization, which is efficiently solved by using a scaled-gradient trust-region approach with Broyden Jacobian update. Based on this NLSQ formulation, a multiuser harmonized margin (MHM) optimization algorithm for resource allocation is developed. A Newton–Raphson method is also developed for fast margin estimation and used within the MHM. The MHM algorithm converges efficiently to a solution for the best common equal margin to all users, while explicitly guaranteeing their target rate requirements. (This is the reason for the term harmonized.) Furthermore, its predominantly distributed structure can be implemented in DSL/DSM scenarios with only Level 1 coordination. Simulation results of various cases verify the convergence to the unique optimal solution within 5–10 iterations. 相似文献
17.
18.
19.
20.
Bandler J.W. Zhang Q.J. Song J. Biernacki R.M. 《Microwave Theory and Techniques》1990,38(11):1701-1710
Yield optimization of nonlinear microwave circuits operating in the steady state under large-signal periodic excitations is studied. Two novel high-speed methods of gradient calculation, the integrated gradient approximation technique (IGAT) and the feasible adjoint sensitivity technique (FAST) are introduced. IGAT utilizes the Broyden formula with special iterations of Powell to update the approximate gradients. FAST combines the efficiency and accuracy of the adjoint sensitivity technique with the simplicity of the perturbation technique. IGAT and FAST are compared with the simple perturbation approximate sensitivity technique (PAST) on the one extreme and the theoretical exact adjoint sensitivity technique (EAST) on the other. A FET frequency doubler example treats statistics of both linear elements and nonlinear device parameters. This design has six optimizable variables, including input power and bias conditions, and 34 statistical parameters. Using either IGAT or FAST, yield is driven from 40% to 70%. FAST exhibits superior efficiency 相似文献