Making automated computer program documentation a feature of total system design

It is pointed out that in large-scale computer software systems, program documents are too often fraught with errors, out of date, poorly written, and sometimes nonexistent in whole or in part. The means are described by which many of these typical system documentation problems were overcome in a large and dynamic software project. A systems approach was employed which encompassed such items as: (1) configuration management; (2) standards and conventions; (3) collection of program information into central data banks; (4) interaction among executive, compiler, central data banks, and configuration management; and (5) automatic documentation. A complete description of the overall system is given

Structure determination of the reconstructed Au(110) surface

The LEED pattern of the Au(110) surface shows a (1 × 2) and also a (1× 3) superstructure. The (1 × 2) superstructure has been determined by comparison of LEED intensities with model calculations. The missing row model is the most probable model. A minimum of the averaged r-factor, , has been found for 15% contraction of the first layer spacing without atomic displacements in the second layer

P31 phosphor persistence at photopic mean luminance level.

P31 phosphor screens are frequently used for short-term presentation of dot and grating patterns, but experimental data obtained with this technique have been criticized because of possible parasitic effects of phosphor persistence on subjects' visual performance. Recently, this issue provoked a controversial discussion in Vision Research (Groner et al., 1993; Westheimer, 1993, 1994; Irwin, 1994; Di Lollo et al., 1994) which was concerned with persistence effects of P31 screens for dot patterns. Supplementing this discussion, the present work deals with the effects of different types of patterns (dot pattern vs. gratings) and background mean-luminance levels (scotopic vs. phototopic) on phosphor persistence. Physical measurements of P31 persistence occurring with grating patterns of a mean luminance of 20 cd m-2 (i.e. photopic range) were obtained by using an extremely linear photometer with high temporal resolution. Under this photopic condition, the measurements demonstrate a fast decay of residual grating contrast to 1.4% of its original value within 50 ms after pattern offset. This phosphor behavior must be considered when designing an experiment with a P31 screen though it certainly embodies no problems in many applications

Detecting planets in protoplanetary disks: A prospective study

We investigate the possibility to find evidence for planets in circumstellar disks by infrared and submillimeter interferometry. We present simulations of a circumstellar disk around a solar-type star with an embedded planet of 1 Jupiter mass. The three-dimensional (3D) density structure of the disk results from hydrodynamical simulations. On the basis of 3D radiative transfer simulations, images of this system were calculated. The intensity maps provide the basis for the simulation of the interferometers VLTI (equipped with the mid-infrared instrument MIDI) and ALMA. While MIDI/VLTI will not provide the possibility to distinguish between disks with or without a gap on the basis of visibility measurements, ALMA will provide the necessary basis for a direct gap detection.Comment: 5 page

The true complexity of a system of linear equations

It is well-known that if a subset A of a finite Abelian group G satisfies a quasirandomness property called uniformity of degree k, then it contains roughly the expected number of arithmetic progressions of length k, that is, the number of progressions one would expect in a random subset of G of the same density as A. One is naturally led to ask which degree of uniformity is required of A in order to control the number of solutions to a general system of linear equations. Using so-called "quadratic Fourier analysis", we show that certain linear systems that were previously thought to require quadratic uniformity are in fact governed by linear uniformity. More generally, we conjecture a necessary and sufficient condition on a linear system L which guarantees that any subset A of F_p^n which is uniform of degree k contains the expected number of solutions to L.Comment: 30 page

Linear forms and higher-degree uniformity for functions on Fpn\mathbb{F}_p^n

In [GW09a] we conjectured that uniformity of degree $k-1$ is sufficient to control an average over a family of linear forms if and only if the $k$th powers of these linear forms are linearly independent. In this paper we prove this conjecture in $\mathbb{F}_p^n$, provided only that $p$ is sufficiently large. This result represents one of the first applications of the recent inverse theorem for the $U^k$ norm over $\mathbb{F}_p^n$ by Bergelson, Tao and Ziegler [BTZ09,TZ08]. We combine this result with some abstract arguments in order to prove that a bounded function can be expressed as a sum of polynomial phases and a part that is small in the appropriate uniformity norm. The precise form of this decomposition theorem is critical to our proof, and the theorem itself may be of independent interest.Comment: 40 page

Adaptive wall technology for minimization of wall interferences in transonic wind tunnels

Modern experimental techniques to improve free air simulations in transonic wind tunnels by use of adaptive wall technology are reviewed. Considered are the significant advantages of adaptive wall testing techniques with respect to wall interferences, Reynolds number, tunnel drive power, and flow quality. The application of these testing techniques relies on making the test section boundaries adjustable and using a rapid wall adjustment procedure. A historical overview shows how the disjointed development of these testing techniques, since 1938, is closely linked to available computer support. An overview of Adaptive Wall Test Section (AWTS) designs shows a preference for use of relatively simple designs with solid adaptive walls in 2- and 3-D testing. Operational aspects of AWTS's are discussed with regard to production type operation where adaptive wall adjustments need to be quick. Both 2- and 3-D data are presented to illustrate the quality of AWTS data over the transonic speed range. Adaptive wall technology is available for general use in 2-D testing, even in cryogenic wind tunnels. In 3-D testing, more refinement of the adaptive wall testing techniques is required before more widespread use can be planned

Supersonic wind tunnel nozzles: A selected, annotated bibliography to aid in the development of quiet wind tunnel technology

This bibliography, with abstracts, consists of 298 citations arranged in chronological order. The citations were selected to be helpful to persons engaged in the design and development of quiet (low disturbance) nozzles for modern supersonic wind tunnels. Author, subject, and corporate source indexes are included to assist with the location of specific information

Spike Clustering and Neuron Tracking over Successive Time Windows

This paper introduces a new methodology for tracking signals from individual neurons over time in multiunit extracellular recordings. The core of our strategy relies upon an extension of a traditional mixture model approach, with parameter optimization via expectation-maximimization (EM), to incorporate clustering results from the preceding time period in a Bayesian manner. EM initialization is also achieved by utilizing these prior clustering results. After clustering, we match the current and prior clusters to track persisting neurons. Applications of this spike sorting method to recordings from macaque parietal cortex show that it provides significantly more consistent clustering and tracking results

Passenger ride quality response to an airborne simulator environment

The present study was done aboard a special aircraft able to effect translations through the center of gravity with a minimum of pitch and roll. The aircraft was driven through controlled motions by an on-board analog computer. The input signal was selectively filtered Gaussian noise whose power spectra approximated that of natural turbulence. This input, combined with the maneuvering capabilities of this aircraft, resulted in an extremely realistic simulation of turbulent flight. The test flights also included varying bank angles during turns. Subjects were chosen from among NASA Flight Research Center personnel. They were all volunteers, were given physical examinations, and were queried about their attitudes toward flying before final selection. In profile, they were representative of the general flying public. Data from this study include (1) a basis for comparison with previous commercial flights, that is, motion dominated by vertical acceleration, (2) extension to motion dominated by lateral acceleration, and (3) evaluation of various bank angles