Efficient Simulation Algorithm Research Articles

An efficient algorithm for parametric fault simulation of monolithic IC's

An efficient methodology for performing fault simulation experiments as part of an IC failure diagnosis system is described. The methodology uses regression models that relate IC performance directly to process disturbances inherent in all IC fabrication processes. An efficient algorithm for establishing the structure of such models based on data obtained from coupled process and circuit simulators is developed. It selects a minimum number of significant input parameters and automatically establishes an optimum order polynomial regression model. Moreover. the regression models obtained contain information about the structure of the dependence of IC performances on the process disturbances, which can be coded in a dependency tree for each IC performance and used directly for diagnostic purposes. The algorithm belongs to the class of artificial neural network approaches and has been implemented in a program called MULREG (multilayer regression). Two examples of analyzing MULREG are given. >

Real-Time Multibody System Dynamic Simulation: Part II. A Parallel Algorithm and Numerical Results

ABSTRACT This paper presents a computational algorithm that exploits inherent parallelism in the modified recursive formulation presented in Part I of the paper. Computational data flows to implement the algorithm are defined. By combining the topological analysis method presented in Part 1 of the paper, an efficient general purpose dynamic simulation algorithm is developed. Examples using the code developed show that real-time simulation can be achieved for moderately complex mechanical systems using a shared memory multiprocessor.

Dynamic simulation of autonomous legged locomotion

Accurate simulation of Newtonian mechanics is essential for simulating realistic motion of joined figures. Dynamic simulation requires, however, a large amount of computation when compared to kinematic methods, and the control of dynamic figures can be quite complex. We have implemented an efficient forward dynamic simulation algorithm for articulated figures which has a computational complexity linear in the number of joints. In addition, we present a strategy for the coordination of the locomotion of a six-legged figure - a simulated insect - which has two main components: a gait controller which sequences stepping, and motor programs which control motions of the figure by the application of forces. The simulation is capable of generating gait patterns and walking phenomena observed in nature, and our simulated insect can negotiate planar and uneven terrain in a realistic manner. The motor program techniques should be generally applicable to other control problems.

Geometric properties of random disk packings

Random packings ofN⩽2000 rigid disks in the plane, subject to periodic boundary conditions on a square primitive cell, have been generated by a concurrent construction which treats all disks on an equal footing, as opposed to previously investigated sequential constructions. The particles start with random positions and velocities, and as they move about they grow uniformly in size, from points to jammed disks. The collection of packings displays several striking geometric features. These include (for largeN) typically polycrystalline textures with irregular grain boundaries and linear shear fractures. The packings occasionally contain monovacancies and trapped but unjammed “rattler” disks. The latter appear to be confined to the grain boundaries. The linear shear fractures preserve bond orientational order, but disrupt translational order, within the crystalline grains. A new efficient event-driven simulation algorithm is employed to generate the histories of colliding and jamming disks. On a computer which can process one million floating-point instructions per second the algorithm processes more than one million pairwise collisions per hour.

An integration method for dynamic simulation of cycled processes

An integration method of Petzold (SIAM J. Numer. Analysis 18, 455–479, 1981) is modified to yield an efficient algorithm for dynamic simulation of nonsingular periodically cycled chemical processes. Application of the algorithm is demonstrated on a dynamic simulation of controlled cycling distillation. The computer time expenditure is only around 10% of the time required to evaluate the transient using a conventional integration method.

Interacting binary galaxies. II - Matching models to observations

view Abstract Citations (26) References (25) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Interacting Binary Galaxies. II. Matching Models to Observations Borne, Kirk D. Abstract This paper presents an efficient numerical simulation algorithm for the study of interacting elliptical galaxies. Each model galaxy, represented by a collection of gravitating particles, can be (1) endowed with arbitrary degrees of flattening and rotation, (2) oriented in any spatial direction, (3) evolved along any chosen orbital trajectory for an arbitrary length of time, and (4) projected onto the "sky" of a randomly oriented observer. How "observations" of simulated tidal interactions between model galaxies are best matched to the measured properties of real binaries is discussed in detail. Rotation curves, radial variations in velocity dispersion, and surface density maps are all matched to the data in an effort to determine the physical state of an observed pair. Strong support is given to the acquisition of velocity measurements and to their application in any model-matching efforts. That the combined spectroscopic and photometric data for specific binaries can be reproduced by appropriate projections of select numerical simulations of the pairs is demonstrated in the companion papers (Papers III and IV). Each matching simulation constrains the masses of the galaxies, their internal dynamics, the properties of their relative orbit, and the three-dimensional orientation of the pair in space. The uniqueness of such dynamical solutions is discussed in detail in the context of a particular representation of the binary orbits: the specification of their speed and separation at pericenter. It is shown that tidal impulse and duration of pericenter passage are the relevant physical parameters affecting the observed tidal distortions in colliding galaxies. Provided that the images of such systems are supplemented with detailed kinematic data, the study of tidally distorted binary galaxies thus represents a fertile avenue to the direct measurement of galaxy masses. Publication: The Astrophysical Journal Pub Date: July 1988 DOI: 10.1086/166453 Bibcode: 1988ApJ...330...38B Keywords: Astronomical Models; Computerized Simulation; Elliptical Galaxies; Galactic Clusters; Galactic Mass; Galactic Structure; Interacting Galaxies; Algorithms; Dark Matter; Dynamical Systems; Velocity Distribution; Astrophysics; GALAXIES: CLUSTERING; GALAXIES: INTERNAL MOTIONS; GALAXIES: STRUCTURE full text sources ADS | Related Materials (6) Part 1: 1984ApJ...287..503B Part 3: 1988ApJ...330...51B Part 4: 1988ApJ...330...61B Part 5: 1988ApJ...333..567B Part 6: 1989ApJ...336..655B Part 7: 1994ApJ...435...79B

An Efficient Algorithm for the Time-Domain Simulation of Regulated Energy-Storage DC-to-DC Converters

An algorithm is presented for the efficient and accurate simulation of switched-mode piecewise-linear systems, a subclass of which includes regulated energy-storage dc-to-dc converters. Three key features of the new algorithm that lead to significant improvements in computational efficiency and accuracy are 1) a state-transition-matrix table-lookup scheme to solve differential equations describing the system, 2) a modified binary-search strategy to obtain an initial estimate of the instant at which the system topology switches, and 3) a quadratic extrapolation for the accurate final determination of the switching instant. The computational efficiency of a program using the new algorithm is demonstrated by comparing its execution time with that of a program employing a standard fixed-step-size integration algorithm. The accuracy of the new algorithm is verified by comparing results obtained from the simulations with results obtained analytically, and by comparing data from the simulation of two different regulated converters with data measured experimentally.

An analysis of ternary simulation as a tool for race detection in digital MOS circuits

Recently, Bryant developed a new switch level model for the functional simulation of race-free digital MOS circuits. The model establishes a formal correspondence to classical circuit theory. Thus the correctness of any simulation algorithm w.r.t. this model is a strong justification for using the algorithm. In [4,12] correct and efficient algorithms have been reported for simulating circuits that do not have internal race conditions. In [1] Bryant suggests to use ‘ternary’ simulation for detecting race conditions in MOS circuits. He justifies his simulation method with a couple of example circuits; however, he does not extend the simulation model to cover circuits that have internal races. In this paper we develop a general framework for simulating MOS circuits that may have race conditions. We use this framework to prove Bryant's conjecture in a suitable extension of his simulation model. We give efficient simulation algorithms for the model and remark on its limitations.

An efficient algorithm for the brownian dynamics simulation of aggregation

Computer simulation techniques have proven to be quite useful for studying the structure of particulates produced by the process of growth through the aggregation of smaller particles. In this paper we introduce an efficient algorithm for use in the computer simulation of the kinetics of the growth of particulates. The new algorithm is based on sorting and data structures for set manipulations. Computer tests indicate that running time is reduced by a factor of four as compared to “conventional” methods.

An efficient DC fault simulation algorithm for nonlinear circuits

An efficient DC fault simulation algorithm for nonlinear circuits is proposed in which Householder’s transform and the method of partitioned matrices are used to minimize the number of operations for fault simulation. The algorithm is also applicable to DC analysis for nonlinear circuits.

Filter approaches to wave kinematics approximation

Time invariant analog filters are presented which are appropriate for approximating ocean wave kinematics described stochastically. The JONSWAP spectrum is used for the statistical characterization of the wave elevation. Further, linear (Airy) theory results are invoked for the variation with depth of the wave spectra. It is shown that these approximations allow closed form calculations of wave related statistics, and lead to efficient digital simulation algorithms of wave kinematics records.

Thermodynamical approach to the traveling salesman problem: An efficient simulation algorithm

We present a Monte Carlo algorithm to find approximate solutions of the traveling salesman problem. The algorithm generates randomly the permutations of the stations of the traveling salesman trip, with probability depending on the length of the corresponding route. Reasoning by analogy with statistical thermodynamics, we use the probability given by the Boltzmann-Gibbs distribution. Surprisingly enough, using this simple algorithm, one can get very close to the optimal solution of the problem or even find the true optimum. We demonstrate this on several examples. We conjecture that the analogy with thermodynamics can offer a new insight into optimization problems and can suggest efficient algorithms for solving them.

An efficient algorithm for simulation on transients in large power systems

The simulation of the transient response of a large interconnected power system involves the solution of a very large system of differential-algebraic equations under a great variety of initial conditions and disturbances. The demands imposed on a digital transient stability program to i) study larger power system interconnections, ii) provide a more detailed representation of the power system components, and iii) permit the simulation of longer time periods, have the effect of increasing the computing time. The importance of, and the need for, efficient computational schemes is apparent. The method presented in this paper makes detailed use of the structural properties of the differential-algebraic system representation. The nonlinear differential-algebraic system is split into a nonstiff part with long time constants coupled to a stiff part with a sparse Jacobian matrix whose longest time constant is shorter than that of the first part. These two parts are linear in their respective states, i.e., the system is semilinear. With the nonstiff part removed, a smaller set of stiff equations with a smaller conditioning number than the original system is obtained. Consequently, longer stepsizes can be used so as to reduce the computation time. The proposed multistep integration schemes exploit the stiffness and semilinearity properties. Numerical results on a small test problem indicate that these schemes operate with good accuracy at stepsizes as large as 100 times those necessary to ensure numerical stability by more conventional schemes.