Showing papers by "Alberto Sangiovanni-Vincentelli published in 1979"

A multilevel Newton algorithm with macromodeling and latency for the analysis of large-scale nonlinear circuits in the time domain

Abstract: Analysis techniques which take advantage of the structural properties of large-scale electrical networks are discussed. Exact macromodels of a subnetwork are defined and a sufficient condition on the subnetwork equations for the existence of a macromodel is given. A multilevel Newton algorithm based on macromodels is presented. The algorithm is shown to have local quadratic convergence provided that suitable conditions on the continuity and nonsingularity of the Jacobian of the network equations are satisfied. The concept of latency for the analysis of large-scale networks in the time domain is discussed. The relationship between latency and numerical integration methods is investigated.

Theoretical and computational aspects of the optimal design centering, tolerancing, and tuning problem

Abstract: The optimal design centering, tolerancing, and tuning problem is transcribed into a mathematical programming problem of the form P_g: \min\{f(x)|\max_{\omega\in\Omega}\min_{\tau\in\Gamma} \zeta^{j}(x,\omega, \tau) \leq 0\} , x \geq 0, x, \omega, \tau \in R^{n} , f: R^n \rightarrow R^1 , \zeta: R^n \times R^n \times R^n \rightarrow R^1 , continuously differentiable, \Omega and T compact subsets of R^n , J=\{1, \cdots , p\} . A simplified form of P_g , P: \min \{f(x) \Psi (x) \underset{=}{\triangle} \max_{omega\in \Omega \min_{\tau \in T} \zeta(x,\omega, \tau ) \leq 0 \} is discussed. It is shown that $\Psi(\cdot ) is locally Lipschitz continuous but not continuously differentiable. Optimality conditions for P based on the concept of generalized gradients are derived. An algorithm, consisting of a master outer approximations algorithm proposed by Gonzaga and Polak and of a new subalgorlthm for nondifferentiable problems of the form P_{i}: \min\{f(x)| \max_{\omega\in\Omega_i\} \min_{\tau \in T} \zeta (x, \omega, \tau ) \leq 0 \} , where \Omega_i is a discrete set, is presented. The subalgorlthm, an extension of Polak's method of feasible directions to nondifferentlable problems, is shown to converge under suitable assumptions. Moreover, the optimality function used in the subalgorithm is proven to satisfy a condition which guarantees that the overall algorithm converges.

Via assignment problem in multilayer printed circuit board

Abstract: In the routing of a multilayer printed circuit board an important phase is the via assignments. In this paper, the via assignment problem is given a graph theoretic formulation. Some related optimization problems are proven to belong to a particular class of hard combinatorial problem: the class of nondeterministic polynomial (NP)-complete problems. This result suggests that the only way to solve efficiently the optimization problems is to introduce heuristic algorithms. Hence, some heuristic algorithms a proposed and their performances are evaluated.

Bipartite graphs and an optimal bordered triangular form of a matrix

Abstract: The problem of determining row and column permutations to transform a nonsingular (not necessarily symmetric) matrix to a minimum k k -bordered lower triangular form is shown to be an NP -complete (Intrinsically difficult) problem by treating an equivalent bipartite graph problem-determine a minimum essential dumbbell set. A (sequential, rather than backtrack oriented) algorithm is described by which to obtain a minimal (local minimum, rather than minimum) essential dumbbell set, hence, also a minimal k k -bordered lower triangular form of a matrix. The performance of an APL realization of the algorithm is illustrated and data to justify an embedded heuristic is provided.

Optimal printed circuit board ordering via hart‐nilsson‐raphael‐algorithm

Abstract: A layout problem, the optimal ordering of printed circuit boards equally spaced on a straight line, is investigated. An optimal algorithm whose structure is based on the Hart, Nilsson and Raphael algorithm is presented and its complexity evaluated. Since the intrinsic complexity of the problem is shown to be very high, an approximated algorithm is introduced and its performances are evaluated. Experimental results are discussed to emphasize the efficiency of the approximated algorithm.

An edge‐oriented adjacency list for undirected graphs

Abstract: A new data structure, called the Edge-Oriented Adjacency List (EOAL), for representing undirected graphs is presented. It provides more information on the edges and requires less storage space than the conventional adjacency list. Furthermore, it is superior to the conventional adjacency list in both insertion and deletion operations.

Models for thyristors and diode in digital simulations

Abstract: Two models are proposed for digital simulations involving power diodes and thyristors. The models simulate all operating regions of the devices, and include transient and thermal behavior. Particular emphasis has been placed on reverse recovery behaviors, to improve simulation accuracy in high frequency and multiple device applications. Either model can be completely specified from standard data sheet parameters.