The Infrared Spectrograph on the Spitzer Space Telescope

The Infrared Spectrograph (IRS) instrument on the Spitzer Space Telescope covered the 5 to 38 micron wavelength range at low and medium spectral resolutions. The instrument was very popular during Spitzers 5.7 year-long cold mission. Every year it attracted the most proposals, and garnered more observing hours, of any of the science instruments. This success was the culmination of a very long development period, where the instrument design changed radically. When the instrument was first selected by NASA in 1984 it was very complicated. As part of the overall reduction of the size of the SIRTF Observatory following its recovery from the missions cancellation in 1991 the IRS became smaller and much, much simpler. The only aspect of the instrument that increased from the original design was the pixel count of the detectors. The new, lean, IRS based on eight axioms: (1) SIRTF is a cost-driven mission; (2) Only Boeing Si:As and Si:Sb 128x128 BIB arrays shall be used; (3) The IRS has all Aluminum housing and optics; (4) Simple optics consisting of surfaces of revolution, flat gratings, and bolt-and-go tolerances; (5) No moving parts; (6) Redundancy only for credible single-point failures; (7) Strive for an observing efficiency of 80%; (8) The IRS shall be capable of internal health assessment. This led to a simple, robust, but still extremely powerful final instrument composed of four distinct modules. Many of the features developed for the IRS were subsequently employed in other spacecraft and SOFIA science instrumentation. This presentation will cover the developmental history of the IRS instrument, its final design and performance, and will especially highlight the sage decisions that Jim Houck made along the way that led to its highly successful career on the Spitzer Space Telescope

Flight-testing of the self-repairing flight control system using the F-15 highly integrated digital electronic control flight research facility

Flight tests conducted with the self-repairing flight control system (SRFCS) installed on the NASA F-15 highly integrated digital electronic control aircraft are described. The development leading to the current SRFCS configuration is highlighted. Key objectives of the program are outlined: (1) to flight-evaluate a control reconfiguration strategy with three types of control surface failure; (2) to evaluate a cockpit display that will inform the pilot of the maneuvering capacity of the damage aircraft; and (3) to flight-evaluate the onboard expert system maintenance diagnostics process using representative faults set to occur only under maneuvering conditions. Preliminary flight results addressing the operation of the overall system, as well as the individual technologies, are included

A role for the developing lexicon in phonetic category acquisition

Infants segment words from fluent speech during the same period when they are learning phonetic categories, yet accounts of phonetic category acquisition typically ignore information about the words in which sounds appear. We use a Bayesian model to illustrate how feedback from segmented words might constrain phonetic category learning by providing information about which sounds occur together in words. Simulations demonstrate that word-level information can successfully disambiguate overlapping English vowel categories. Learning patterns in the model are shown to parallel human behavior from artificial language learning tasks. These findings point to a central role for the developing lexicon in phonetic category acquisition and provide a framework for incorporating top-down constraints into models of category learning

Three-dimensional multigrid algorithms for the flux-split Euler equations

The Full Approximation Scheme (FAS) multigrid method is applied to several implicit flux-split algorithms for solving the three-dimensional Euler equations in a body fitted coordinate system. Each of the splitting algorithms uses a variation of approximate factorization and is implemented in a finite volume formulation. The algorithms are all vectorizable with little or no scalar computation required. The flux vectors are split into upwind components using both the splittings of Steger-Warming and Van Leer. The stability and smoothing rate of each of the schemes are examined using a Fourier analysis of the complete system of equations. Results are presented for three-dimensional subsonic, transonic, and supersonic flows which demonstrate substantially improved convergence rates with the multigrid algorithm. The influence of using both a V-cycle and a W-cycle on the convergence is examined

Universal Properties of Galactic Rotation Curves and a First Principles Derivation of the Tully-Fisher Relation

In a recent paper McGaugh, Lelli, and Schombert showed that in an empirical plot of the observed centripetal accelerations in spiral galaxies against those predicted by the Newtonian gravity of the luminous matter in those galaxies the data points occupied a remarkably narrow band. While one could summarize the mean properties of the band by drawing a single mean curve through it, by fitting the band with the illustrative conformal gravity theory with fits that fill out the width of the band we show here that the width of the band is just as physically significant. We show that at very low luminous Newtonian accelerations the plot can become independent of the luminous Newtonian contribution altogether, but still be non-trivial due to the contribution of matter outside of the galaxies (viz. the rest of the visible universe). We present a new empirical plot of the difference between the observed centripetal accelerations and the luminous Newtonian expectations as a function of distance from the centers of galaxies, and show that at distances greater than 10 kpc the plot also occupies a remarkably narrow band, one even close to constant. Using the conformal gravity theory we provide a first principles derivation of the empirical Tully-Fisher relation.Comment: 6 pages, 15 figures. The paper is a comment on S. S. McGaugh, F. Lelli, and J. M. Schombert, Phys. Rev. Lett. 117, 201101 (2016). Updated to include a first principles derivation of the Tully-Fisher relation using the conformal gravity theory. Submitted to Physics Letters

Multimodal Observation and Interpretation of Subjects Engaged in Problem Solving

In this paper we present the first results of a pilot experiment in the capture and interpretation of multimodal signals of human experts engaged in solving challenging chess problems. Our goal is to investigate the extent to which observations of eye-gaze, posture, emotion and other physiological signals can be used to model the cognitive state of subjects, and to explore the integration of multiple sensor modalities to improve the reliability of detection of human displays of awareness and emotion. We observed chess players engaged in problems of increasing difficulty while recording their behavior. Such recordings can be used to estimate a participant's awareness of the current situation and to predict ability to respond effectively to challenging situations. Results show that a multimodal approach is more accurate than a unimodal one. By combining body posture, visual attention and emotion, the multimodal approach can reach up to 93% of accuracy when determining player's chess expertise while unimodal approach reaches 86%. Finally this experiment validates the use of our equipment as a general and reproducible tool for the study of participants engaged in screen-based interaction and/or problem solving

Computation of laminar viscous-inviscid interactions in high-speed internal flows

A review is given of computations for a series of nominally 2-D laminar viscous-inviscid interactions. Comparisons were made with detailed experimental shock tunnel results. The shock wave boundary layer interactions considered were induced by a compression ramp in one case and by an externally generated incident shock in the second case. In general, good agreement was reached between the grid refined calculations and experiment for the incipient and small separation conditions. For the highly separated flow, 3-D calculations which included the finite span effects of the experiment were required in order to obtain agreement with the data

Space physics analysis network node directory (The Yellow Pages): Fourth edition

The Space Physics Analysis Network (SPAN) is a component of the global DECnet Internet, which has over 17,000 host computers. The growth of SPAN from its implementation in 1981 to its present size of well over 2,500 registered SPAN host computers, has created a need for users to acquire timely information about the network through a central source. The SPAN Network Information Center (SPAN-NIC) an online facility managed by the National Space Science Data Center (NSSDC) was developed to meet this need for SPAN-wide information. The remote node descriptive information in this document is not currently contained in the SPAN-NIC database, but will be incorporated in the near future. Access to this information is also available to non-DECnet users over a variety of networks such as Telenet, the NASA Packet Switched System (NPSS), and the TCP/IP Internet. This publication serves as the Yellow Pages for SPAN node information. The document also provides key information concerning other computer networks connected to SPAN, nodes associated with each SPAN routing center, science discipline nodes, contacts for primary SPAN nodes, and SPAN reference information. A section on DECnet Internetworking discusses SPAN connections with other wide-area DECnet networks (many with thousands of nodes each). Another section lists node names and their disciplines, countries, and institutions in the SPAN Network Information Center Online Data Base System. All remote sites connected to US-SPAN and European-SPAN (E-SPAN) are indexed. Also provided is information on the SPAN tail circuits, i.e., those remote nodes connected directly to a SPAN routing center, which is the local point of contact for resolving SPAN-related problems. Reference material is included for those who wish to know more about SPAN. Because of the rapid growth of SPAN, the SPAN Yellow Pages is reissued periodically