Dimensional Codes Research Articles

Combined application of surface flow visualization and laser-Doppler anemometry to engine intake flows

Flow visualization using oil streak techniques and laser-Doppler anemometry were carried out to provide detailed information on the flow through the intake valve of a research (model) engine head under steady flow conditions. The work was partially undertaken to develop the techniques as useful tools for engine research. On the other hand, variations of the flow field with valve lift and with valve location were of interest. In the present paper it is shown that a symmetric geometry does not necessarily result in symmetric flow patterns inside the cylinder; the tendency to asymmetry increases with increasing valve lift. These characteristics of the flow should be taken into account when flow computations are performed necessitating the use of three dimensional codes in the entire flow field, not in a symmetrical half-geometry.

Numerical Integration--Recent Developments, Software and Applications.

Theoretical Aspects of One-Dimensional Quadrature.- The convergence of noninterpolatory product integration rules.- Some quadrature rules for finite trigonometric and related integrals.- Modified Clenshaw-Curtis integration and applications to numerical computation of integral transforms.- Fast generation of quadrature rules with some special properties.- Quadrature methods for the determination of zeros of transcendental functions - a review.- Computation of the index of an analytic function.- Approximate computation of strongly oscillatory integrals with compound precision.- Bounds and approximations for the zeros of classical orthogonal polynomials. Their use in generating quadrature rules..- Indefinite integration formulas based on the sinc expansion.- On positive quadrature rules.- Quadrature rules with end-point corrections - comments on a paper by Garloff, Solak and Szydelko.- Comparison of Gauss-Hermite and midpoint quadrature with application to the Voigt function.- Theoretical Aspects of Multiple Quadrature.- On sequences of imbedded integration rules.- Asymptotic expansions and their applications in numerical integration.- Construction of three-dimensional cubature formulae with points on regular and semi-regular polytopes.- Construction of sequences of embedded cubature formulae for circular symmetric planar regions.- On the construction of higher degree three dimensional embedded integration rules.- Fully symmetric integration rules for the unit four-cube.- On the construction of cubature formulae with few nodes using Groebner bases.- Quasi-random sequences for optimization and numerical integration.- Non-fortuitous, non-product, non-fully symmetric cubature structures.- Algorithms, Software and Applications.- A parallelization of adaptive integration methods.- The numerical evaluation of multiple integrals on parallel computers.- Vectorisation of one dimensional quadrature codes.- Performance of self-validating adaptive quadrature.- Using weight functions in self-validating quadrature.- On the construction of a practical Ermakov-Zolotukhin multiple integrator.- Interactive numerical quadrature.- The design of a generic quadrature library in Ada.- The integration of the multivariate normal density function for the triangular method.- Numerical integration in scalar wave scattering, with application to acoustic scattering by fish.- Software Classification and Testing.- Testing multiple integrators.- A package for testing multiple integration subroutines.- A test of some well known one dimensional general purpose automatic quadrature routines.- Development of useful quadrature software, with particular emphasis on microcomputers.- Appendix I: Final Program.- Appendix II: Discussion.- List of Participants.- List of Contributors.

Computer Modelling of Two- and Three-Dimensional Cavities

The rf accelerating system is the heart of many low, medium and high energy particle accelerators and in many cases, it is also a major drain of investement money and operational costs. In order to increase efficiency, many computer codes have been developed in the last few decades. Recently, it has been realized that parasitic collective effects can also present serious problems in the most expensive front line high energy physics accelerators. Nowadays, cavity design is no longer only a question of optimizing the shunt impedance but also of optimizing the overall effect of the system. Also, all other non-rf cavities in an accelerator are found to cause many problems. For cylindrically symmetric structures well tested computer codes are in widespread routine use as design tools. Fully three dimensional codes are just coming into common operation. At the present time, we are able to solve almost every two or three dimensional cavity problem either by mode computation or by transient wake field computation.

Penetration of RF Fields into Holes in Cavity Walls

Measurements of magnetic fields in cavity wall penetrations were made to provide engineering data for practical cavity design. The data were normalized to cavity wall fields and, as expected, when all coordinates were scaled by the transverse dimension of the penetration, the measured field distributions were similar and differed by only small systematic amounts. These data are thus generally applicable to any standard rf cavity, independent of frequency, provided only that the penetration, when regarded as a waveguide, is well below cutoff frequency. Until the results of three dimensional rf cavity codes are commonly available, these numbers should assist design engineers in detailing the properties of tuning plungers, drive loops, pumping ports and view ports.

Sets of One and Higher Dimensional Welti Codes and Complementary Codes

A Welti code is a binary sequence with an impulse-like autocorrelation function. A set of such codes may possess vanishing cross-correlation functions. The elements of Welti codes must be members of a set of at least two orthogonal vectors or subcodes. First, methods for synthesizing sets of one-dimensional Welti codes with vanishing cross-correlation functions, and conditions upon their existence are discussed. Then, construction methods of sets of two and higher dimensional Welti codes are presented. Based on these constructions, further sets of mutually orthogonal complementary codes in one or more dimensions can be derived. The use of such signals relates to various topics such as communication, radar and navigation systems, measuring and identification in one or higher dimensional systems, synchronization and spatial alignment, or coded aperture imaging.

Gravitational radiation from nonspherical infall into black holes

view Abstract Citations (36) References (17) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Gravitational radiation from nonspherical infall into black holes Shapiro, S. L. ; Wasserman, I. Abstract Strong-field perturbation calculations are performed of the gravitational radiation emitted when spheroidal dust shells of mass m and arbitrary eccentricity fall radially into Schwarzschild black holes of mass M much greater than m. The scaling laws obeyed by the numerical results in limiting eccentricity regimes are derived analytically. It is demonstrated that the total energy emitted in gravitational radiation by a nonspherical dust cloud falling into a black hole is always less than the energy radiated by a point particle of the same mass falling into the hole. The suppression results from interference between waves emitted from different regions of the extended, infalling mass. Nonspherical, radial dust calculations suggest that efficient gravitational wave generation from collapse requires either matter pressure sufficiently strong to induce bounces and shocks or angular momentum. Both the numerical and analytic results should prove useful for the testing of general relativistic, 2+1 dimensional (axisymmetric) hydrodynamical codes which treat both matter and fields. Publication: The Astrophysical Journal Pub Date: September 1982 DOI: 10.1086/160302 Bibcode: 1982ApJ...260..838S Keywords: Black Holes (Astronomy); Gravitational Collapse; Gravitational Waves; Cosmology; Mass Distribution; Scaling Laws; Schwarzschild Metric; Spheroids; Astrophysics full text sources ADS |

A format for DSM-III diagnostic formulation: experience with 1,111 consecutive patients.

The authors present a format that organizes DMS-III diagnoses according to its five axes. For each axis, it provides an ordered listing of several diagnostic categories, their qualification as principal or provisional diagnoses, and alternative categories to be ruled out. For each dimensional axis, the terms and codes of the scale are specified and arranged linearly. This format was used with 1,111 new patients who consecutively applied for care at a comprehensive psychiatric facility during a 6-month period. The authors report on the frequency of use of specific diagnostic categories and dimensional levels along provisional, and rule-out diagnoses were noted.

The smallest length of binary 7–dimensional linear codes with prescribed minimum distance

Let n( k, d) denote the smallest value of n for which a binary ( n, k, d) code exists. Then n( k, d) was known for all d, when k ⩽6. All values of n(7, d) will now be presented.

Comparison of Redundancy Reducing Codes for Facsimile Transmission of Documents

A comparison and a valuation of different redundancy reducing coding techniques for the digital transmission of facsimile documents on telephone lines is presented. Especially taken into account are those codes which have been submitted to the International Telegraph and Telephone Consultative Committee (CCITT) for standardization of digital group 3 facsimile machines. The reduction factor and the sensitivity of channel errors of these one- and two- dimensional codes have been investigated by computer simulations using the CCITT test documents and burst error patterns of real telephone lines. For a resolution of 1728 picture elements per line and 3.85 lines per mm one-dimensional run length coding proves to be the most economical solution. Using a higher vertical resolution of 7.7 lines per mm the effects of transmission errors are less visible in the received document and two-dimensional codes become more efficient. To achieve a transmission time of 1 min or less for a size A4 document a transmission bit rate of 4800 bits/s is required. For the higher vertical resolution a transmission time of 1 min cannot be guaranteed for all types of documents with this bit rate even if two-dimensional coding is used.

Perfect Codes in the Lee Metric and the Packing of Polyominoes

Perfect Codes in the Lee Metric and the Packing of Polyominoes