Showing papers on "Computation published in 1974"
Book•
01 Jan 1974
TL;DR: This outstanding introductory treatment of graph theory and its applications has had a long life in the instruction of advanced undergraduates and graduate students in all areas that require knowledge of this subject.
1,161 citations
TL;DR: In this paper, a new method for network analysis, the "force density method" is presented, which is based upon the force-length ratios or force densities which are defined for each branch of the net structure.
766 citations
TL;DR: In this paper, a numerical method for the computation of electrostatic fields is described, based on the use of fictitious line charges as particular solutions of Laplace's and Poisson's equations.
Abstract: A numerical method for the computation of electrostatic fields is described. The basis of the method is the use of fictitious line charges as particular solutions of Laplace's and Poisson's equations. Details are given of a digital computer program developed for field calculations by means of this method, and its application is illustrated by practical examples involving two-and three-dimensional geometries.
652 citations
01 Jul 1974
649 citations
TL;DR: The algorithm, introduced here, lends itself to computer programming and provides a method to compute evolutionary distance which is shorter than the other methods currently in use.
Abstract: This paper gives a formal definition of the biological concept of evolutionary distance and an algorithm to compute it. For any set S of finite sequences of varying lengths this distance is a real-valued function on $S \times S$, and it is shown to be a metric under conditions which are wide enough to include the biological application. The algorithm, introduced here, lends itself to computer programming and provides a method to compute evolutionary distance which is shorter than the other methods currently in use.
523 citations
TL;DR: Several theoretical results are developed to obtain an efficient branch-and-bound algorithm for the sequencing problem when all jobs are available to process at time zero and are independent (i.e., there are no precedence relationships among jobs).
Abstract: Several theoretical results are developed to obtain an efficient branch-and-bound algorithm for the sequencing problem when all jobs are available to process at time zero and are independent (i.e., there are no a priori precedence relationships among jobs). The branch-and-bound algorithm and its computational results are given for the case of linear penalty functions. The computational experiences are very encouraging. The computer times required to solve the problems are very short and for most problems the optimum is achieved at the early stages of computation.
127 citations
TL;DR: In this article, the authors describe several modified simulation techniques, based on the use of a space grid of variable dimensions and/or an implicit solution which are of equally general applicability but which reduce computation times by a factor of a hundred without significant loss of accuracy.
115 citations
Journal Article•
104 citations
TL;DR: In this paper, a computer-based method was described for generating a homogeneous assembly of randomly close-packed spheres of packing density 0.606, which is very similar to that of an unshaken pile of ballbearings and does not show the splitting of the second peak that is observed in shaken stacks of ball bearings.
Abstract: A computer-based method is described for generating a homogeneous assembly of randomly close-packed spheres of packing density 0.606. The pair distribution function of this assembly is very similar to that of an unshaken pile of ballbearings and does not show the splitting of the second peak that is observed in shaken stacks of ballbearings. The average number of contacts of the spheres in the computed assembly is 6.0.
99 citations
TL;DR: In this article, a theoretical formulation in terms of combined magnetic and electric field integral equations is presented for the class of electromagnetic problems in which one or more wire antennas are connected to a conducting body of arbitrary shape.
Abstract: A theoretical formulation, in terms of combined magnetic and electric field integral equations, is presented for the class of electromagnetic problems in which one or more wire antennas are connected to a conducting body of arbitrary shape. The formulation is suitable for numerical computation provided that the overall dimensions of the structure are not large compared to the wavelength. A computer program is described, and test runs on various configurations involving a cylindrical body with one or more straight wires are presented. The results obtained agree well with experimental data.
TL;DR: In this paper, a method for the calculation of rays and geometrical spreading of seismic body waves propagating in laterally inhomogeneous media with curved interfaces is suggested. But this method is based on a system of ordinary differential equations of the first order and the initial conditions for these quantities at the interface are derived.
Abstract: Summary
Methods for the calculation of rays and geometrical spreading of seismic body waves propagating in laterally inhomogeneous media with curved interfaces are suggested. Seismic rays and geometric spreading are described by a system of ordinary differential equations of the first order. When the ray impinges on an interface, certain quantities of the above system change discontinuously. The initial conditions for these quantities at the interface are derived. Once the geometrical spreading has been determined the computation of ray amplitudes is easy.
TL;DR: In this article, the authors review the principal methods of estimation of parameters in multivariate autoregressive moving average equations which have additional observable input terms in them and present some new methods of estimability as well.
Abstract: We will review the principal methods of estimation of parameters in multivariate autoregressive moving average equations which have additional observable input terms in them and present some new methods of estimation as well. We begin with the conditions for the estimability of the parameters. In addition to the usual method of system representation, the canonical form I, we will present two new representations of the system equation, the so-called canonical forms II and III which are convenient for parameter estimation. We will mention, in some detail, the various methods of estimation like the various least-squares methods, the maximum likelihood methods, etc., and discuss them regarding their relative accuracy of the estimate and the corresponding computational complexity. We will introduce a new class of estimates, the so-called limited information estimates which utilizes the canonical forms II and III. The accuracy of these estimates is close to that of maximum likelihood, but their computation time is only a fraction of the computation time for the usual maximum likelihood estimates. We will present a few numerical examples to illustrate the various methods.
TL;DR: An algorithm is presented here which implies that every polynomial of degree n with at most s distinct coefficients can be realized with O(n/\log _s n) operations.
Abstract: Many problems, including matrix-vector multiplication and polynomial evaluation, involve the computation of linear forms An algorithm is presented here which offers a substantial improvement on the conventional algorithm for this problem when the coefficient set is small In particular, this implies that every polynomial of degree n with at most s distinct coefficients can be realized with $O(n/\log _s n)$ operations It is demonstrated that the algorithm is sharp for some problems
TL;DR: DiscreteLp-approximation, especially for 1≤p≤2 is useful for practical purposes and the experience with an algorithm for its numerical computation is described.
Abstract: DiscreteL p -approximation, especially for 1≤p≤2 is useful for practical purposes. We describe the experience with an algorithm for its numerical computation.
01 Jul 1974
TL;DR: A comprehensive power system analysis package, PSS/2, is described which has been developed specifically for use with dedicated computers and allows load flow, short-circuit, and dynamic simulation work, data base maintenance, and printed report preparation to be handled in the interactive mode at lower cost than could be possible by alternative batch or time-shared computing methods.
Abstract: The analysis of power system performance has always been enhanced by close interaction between engineer and computation, and recent developments in high-speed displays, minicomputer capacity, and computational technology are encouraging major revisions of computing practices for power system analysis. A comprehensive power system analysis package, PSS/2, is described which has been developed specifically for use with dedicated computers. This dedicated computer approach allows load flow, short-circuit, and dynamic simulation work, data base maintenance, and printed report preparation to be handled in the interactive mode at lower cost than could be possible by alternative batch or time-shared computing methods. The subjects covered are data organization, computational techniques, user interface, and operational experience.
TL;DR: In this article, an approximation theory for Coulombic potential energy integrals was discussed, which led to rigorous error bounds on the difference between exact integrals and proposed approximations.
Abstract: In a previous study of Coulombic potential energy integrals, an approximation theory was discussed which led to rigorous error bounds on the difference between exact integrals and proposed approximations. The simple structure of the bound provides a favorable context for introducing approximations of two‐particle electron repulsion integrals which occur in molecular structure theory. Studies of the ethylene and pyridine molecules are reported in an investigation of the utility of the approximations. Comparisons of exact and approximate integrals and theoretical error bounds and analysis of entire integral distributions are presented. Ground state SCF total energies, orbital energies, and molecular orbitals show excellent agreement with the results of computations using exact integrals.
TL;DR: In this article, the linear digital filtering technique developed for the computation of standard curves for conventional resistivity and electromagnetic depth soundings is applied to the determination of filter coefficients for the computations of dipole curves from the resistivity transform function by convolution.
Abstract: The technique of linear digital filtering developed for the computation of standard curves for conventional resistivity and electromagnetic depth soundings is applied to the determination of filter coefficients for the computation of dipole curves from the resistivity transform function by convolution. In designing the filter function from which the coefficients are derived, a sampling interval shorter than the one used in the earlier work on resistivity sounding is found to be necessary. The performance of the filter sets is tested and found to be highly accurate. The method is also simple and very fast in application.
TL;DR: In this paper, fast computer simulation of the electron spin resonance and adiabatic rapid passage spectra of spin labels characterized by rotational correlation times ranging from the fast motion to the rigid lattice limits is demonstrated.
01 Jan 1974
TL;DR: A computationally simple map projection is derived and is shown to have a correspondingly direct inverse, a single empirical parameter, and modest distortional properties, appropriate for rapidly and inexpensively displaying geographical data on an electronic tube under computer control.
Abstract: A computationally simple map projection is derived and is shown to have a correspondingly direct inverse, a single empirical parameter, and modest distortional properties. This is especially appropriate for rapidly and inexpensively displaying geographical data on an electronic tube under computer control, assuming that any computation is to be done using spheroidal formulae but that the computer is to recognize positions pointed at electronically.
TL;DR: In this article, the spherical harmonic analysis (SHA) of scalar intensity F was used for the analysis of simulated data, derived by adding pseudorandom noise to surface values synthesized from existing spherical harmonic coefficients (SHC).
Abstract: We have investigated the spherical harmonic analysis (SHA) of scalar intensity F. The method used was the analysis of simulated data, derived by adding pseudorandom noise to surface values (with equiangular spacing) synthesized from existing spherical harmonic coefficients (SHC). An advantage of using simulated data is that this makes possible the computation of vector as well as scalar residuals. In general, similar results were obtained regardless of whether the number of input SHC used in the synthesis of simulated data was less than, equal to, or greater than the number of output SHC. The main result was that the largest vertical intensity residuals occurred in the equatorial region, the foci following the magnetic dip equator rather than the geographic equator. On account of the equiangular spacing, sine colatitude (sinθ ) weighting was usually used in the SHA. Analyses with other weights at θ = 85° and 95° resulted in no improvement. Substitution of vector for scalar data at these colatitudes gave a much better result. This offers some hope that an improved vector model might be obtained from a real data set composed chiefly of F measurements if it incorporated additional vector measurements in selected areas. Complete vector measurements would of course be still better.
01 Jan 1974
TL;DR: In the case of nilpotent groups, the authors showed that these are more efficiently handled by building the group via the lower central series using the Schur multiplicator than by using a computer.
Abstract: Classical methods of dealing with groups using a computer prove to be unsatisfactory in the case of nilpotent groups Recent work by Macdonald shows that these are more efficiently handled by building the group via the lower central series using the Schur multiplicator
TL;DR: Calculations of the velocity profile, force, moment and bending moment using a theoretical model for the three-dimensional “conical-helical” beat of a cilium of Paramecium multimicro-nucleatum find the mean velocity profile is found to be twisted in form.
01 Jan 1974
TL;DR: In this paper, a direct Cauchy-Riemann solver is used for the nonlinear transonic small-disturbance equations for a biconvex airfoil.
Abstract: Rapid iterative (or semidirect) computation methods are developed for the finite-difference solution of the nonlinear equations of subsonic and transonic aerodynamics. At each iteration, a fast, direct elliptic algorithm solves the entire computation field. In an application to subsonic flow over a lifting airfoil, the full nonlinear stream-function equation is solved. Finally, a direct Cauchy-Riemann solver is used for the nonlinear transonic small-disturbance equations for a biconvex airfoil. At M = 0.7, t/c = 0.1 (subcritical), three iterations on a 39 x 32 mesh (totaling 2.45 sec on an IBM 360/67 computer) obtain convergence within 0.1%. A slightly supercritical case requires seven iterations (6.75 sec) for convergence within 1%.
TL;DR: A brief review of the various methods for the stress computation in finite elements by displacement approximation is given in this article, where the equilibrium equations in the nodal points, the stress resultants are obtained.
TL;DR: This note describes improvements to the assignment algorithm Dial presented to implement his multipath assignment method and illustrates the advantages of Robillard's refinement over the original Dial approach in terms of savings in computation time as well as in core storage.
Abstract: This note describes improvements to the assignment algorithm Dial presented to implement his multipath assignment method. It illustrates the advantages of Robillard's refinement over the original Dial approach in terms of savings in computation time as well as in core storage. Moreover, the note provides some figures on the necessary amount of computation time on a particular computer.
20 Aug 1974
TL;DR: Techniques are described for implementing the hyperplane method for an array computer with a limited form of memory-processor interconnection, such as the Illiac IV, and a new pipelined hyperplanes method is introduced.
Abstract: Techniques are described for implementing the hyperplane method for an array computer with a limited form of memory-processor interconnection, such as the Illiac IV. A new pipelined hyperplane method is introduced. It is useful for compiling a convergent iterative computation, if the computation is programmed with a non-deterministic end of loop test.
TL;DR: The increase in the complexity of the recurrence relations for πn and n more than offset the advantages of Hosemann's proposed redefinition, so the potential savings of a recurrence of Hosesmann's type is not completely realized.
Abstract: Hosemann's recurrence relation for n using Eq. (3) is a considerable improvement over Deirmendjian's entirely different kind of recurrence using Eq. (4). However, it is worth noting that distinct from the intrinsic difference in these recurrences, Hosemann's motivation for redefining n and πn using Eq. (3) rather than Eq. (4) is to contrib ute to his development of a more efficient numerical scheme. But on the contrary, this makes his scheme somewhat less efficient than possible. The increase in the complexity of the recurrence relations for πn and n more than offset the advantages of Hosemann's proposed redefinition, so the potential savings of a recurrence of Hosemann's type is not completely realized. The equations, corresponding to Hosemann's using Eq. (4) are