Physical Sciences and Mathematics Commons^™

Automated Classification Of Stellar Spectra - I. Initial Results With Artificial Neural Networks, Ted Von Hippel, L.J. Storrie-Lombardi, M.C. Storrie-Lombardi, M.J. Irwin

Publications

We have initiated a project to classify stellar spectra automatically from high-dispersion objective prism plates. The automated technique presented here is a simple back propagation neural network and is based on the visual classification work of Houk. The plate material (Houk’s) is currently being digitized, and contains « 105 stars down to K æ 11 at æ 2-Â resolution from « 3850 to 5150 Â. For this first paper in the series, we report on the results of 575 stars digitized from 6 plates. We find that even with the limited data set now in hand we can determine the …

New Sources For The Hot Oxygen Geocorona, P. G. Richards, Michael P. Hickey Ph.D., D. G. Torr

Publications

This paper investigates new sources of thermospheric non thermal (hot) oxygen due to exothermic reactions involving numerous minor (ion and neutral) and metastable species. Numerical calculations are performed for low latitude, daytime, winter conditions, with moderately high solar activity and low magnetic activity. Under these conditions we find that the quenching of metastable species are a significant source of hot oxygen, with kinetic energy production rates a factor of ten higher than those due to previously considered O2+ and NO+ dissociative recombination reactions. Some of the most significant new sources of hot oxygen are reactions involving quenching of O+(²D), O(¹D), …

Comparison Of Theories For Gravity Wave Induced Fluctuations In Airglow Emissions, R. L. Walterscheid, G. Schubert, Michael P. Hickey Ph.D.

Publications

A comparison is undertaken of theories for the gravity wave induced fluctuations in the intensity of airglow emissions and the associated temperature of the source region. The comparison is made in terms of Krassovsky's ratio ηE for a vertically extended emission region (ηE is the ratio of the vertically integrated normalized intensity perturbation to the vertically integrated normalized intensity-weighted temperature perturbation). It is shown that the formulas for ηE in the works by Tarasick and Hines (1990) and Schubert et al. (1991) are in agreement for the case of an inviscid atmosphere. The calculation of ηE using the theory of …

The Multigraph Modeling Tool, Amy Apon, C A. Childers, W H. Hooper, K D. Gordon, L W. Dowdy

Publications

No abstract provided.

Automated Classification Of Stellar Spectra: Where Are We Now?, Ted Von Hippel, L.J. Storrie-Lombardi, M.C. Storrie-Lombardi, M.J. Irwin

Publications

We briefly review the work of the past decade on automated classification of stellar spectra and discuss techniques which show par­ticular promise. Emphasis is placed on Artificial Neural Network and Principle Component Analysis based techniques, due both to our greater familiarity with these and to their rising popularity. As an example of the abilities of current techniques we report on our automated classification work based on the visual classifications of N. Houk (Michigan Spectral Catalogue, Vol. 1 - 4, 1975, 1978, 1982, 1988).

Measuring The Effects Of Thread Placement On The Kendall Square Ksr1, Amy Apon, T D. Wagner, E Smirni, M Madhukar, L W. Dowdy

Publications

This paper describes a measurement study of the effects of thread placement on memory access times on the Kendall Square multiprocessor, the KSRl. The KSRl uses a conventional shared memory programming model in a distributed memory architecture. The architecture is based on a ring of rings of 64-bit superscalar microprocessors. The KSRl has a Cache-Only Memory Architecture (COMA). Memory consists of the local cache memoria attached to each processor. Whenever an address is accessed, the data item is automatically copied to the local cache memory module, 80 that access times for subsequent references will be minimal. If a local cache …

Gravity Wave-Driven Fluctuations In The O2 Atmospheric (0-1) Nightglow From An Extended, Dissipative Emission Region, Michael P. Hickey Ph.D., G. Schubert, R. L. Walterscheid

Publications

The wave-driven fluctuations in the O2(0-1) atmospheric nightglow is modeled and the parameter (eta) is calculated using a model that accounts for either three-body recombination of atomic oxygen atoms alone to form the O2(b exp 1 Sigma(g)(+)) state directly, or by the further inclusion of the process that allows the formation of the O2(c exp 1 Sigma(u)(-)) intermediate state. The calculations are performed for a latitude of 18 deg N and for the months of March and June. The general results, which display how (eta) varies with wave period, horizontal wavelength, season, and chemical scheme, show that for given values …

An Alternative Representation Of The Ice Canopy For Calculating Microwave Brightness Temperatures Over A Thunderstorm, Bradley M. Muller, Henry E. Fuelberg, Eric A. Smith

Publications

Passive microwave brightness temperatures (T(B)'s) at 92 and 183 GHz from an aircraft thunderstorm overflight are compared with values calculated from radar-derived hydrometeor profiles and a modified proximity sounding. Two methods for modeling particles in the ice canopy are contrasted. The first is a ''traditional'' approach employing Marshall-Palmer ice spheres. The second, or ''alternative,'' method partitions 20% of the ice water content into a Marshall-Palmer component for graupel and hail, and 80% into a modified gamma spherical particle size distribution function representing ice crystals.

Results from the alternative approach are superior to those from the traditional method in the anvil …

The Ksr1: Experimentation And Modeling Of Poststore, Amy Apon, E Rosti, E Smirni, T D. Wagner, M Madhukar, L W. Dowdy

Publications

Kendall Square Research introduced the KSRl system in 1991. The architecture is based on a ring of rings of 64bit microprocessors. It is a distributed, shared memory system and is scalable. The memory structure is unique and is the key to understanding the system. Different levels of caching eliminates physical memory addressing and leads to the ALLCACHE TM scheme. Since requested data may be found in any of several caches, the initial access time is variable. Once pulled into the local (sub)cache, subsequent access times are fixed and minimal. Thus, the KSRl is a Cache-Only Memory Architecture (COMA) system. This …

Galactic Structure From Faint Stromgren Photometry: The Catalog Of Observations, Ted A. Von Hippel

Publications

We have initiated the faint photometric survey in the Stromgren system covering about 1 square degree and including 1238 objects in order to develop samples which best probe the thick disk population. The catalog of observations are presented here. They were acquired without kinematic or metallicity biases and are complete to V=17.3-18.5, depending on the field, for 810 early to relatively late type stars. Photometric metallicities were derived for 508 stars and indicate a metal-poor stellar population, consistent with a mixture of thick disk and halo stars. While the Stromgren u-band was not part of the survey, follow-up u-band observations …

Seasonal And Latitudinal Variations Of Gravity Wave-Driven Fluctuations In Oh Nightglow, Michael P. Hickey Ph.D., R. L. Walterscheid, G. Schubert

Publications

The seasonal and latitudinal variations of the gravity wave-driven fluctuations in the OH nightglow are investigated theoretically using a model that accounts for emission from an extended OH layer and includes the effects of eddy diffusivities in the gravity wave dynamics. The mean (unperturbed) state is obtained from a two-dimensional, nighttime model so that mean-state number densities, temperatures and eddy diffusivities are all self-consistent. Seasonal and latitudinal variations in the background OH nightglow emission and in the propagation and dissipation characteristics of the gravity waves influence how the OH nightglow modulations due to gravity waves depend on season and latitude. …

Sic Particles From Asymptotic Giant Branch Stars: Mg Burning And The S-Process, Lawrence E. Brown, Donald D. Clayton

Publications

The question of whether isotopically anomalous SiC particles found in meteorites originate in AGB stars is addressed. It is shown that if the peak helium shell flash temperatures of massive (6-9 solar masses) stars are about 10 percent larger than they are normally assumed to be, alpha particle reactions with the magnesium will become significant. Then the (Mg-29)(alpha, n)Si-29 reaction produces a large excess of Si-29. With a light element nuclear reaction network, the evolution of the silicon isotopic composition during AGB evolution is calculated. It is found that the experimentally determined correlation between excess Si-29 and excess Si-30 in …

Biodegradation Of Dichloromethane And Its Utilization As A Growth Substrate Under Methanogenic Conditions, David L. Freedman, James M. Gossett

Publications

Biodegradation of dichloromethane (DCM) to environmentally acceptable products was demonstrated under methanogenic conditions (35 degrees C). When DCM was supplied to enrichment cultures as the sole organic compound at a low enough concentration to avoid inhibition of methanogenesis, the molar ratio of CH4 formed to DCM consumed (0.473) was very close to the amount predicted by stoichiometric conservation of electrons. DCM degradation was also demonstrated when methanogenesis was partially inhibited (with 0.5 to 1.5 mM 2-bromoethanesulfonate or approximately 2 mM DCM) or completely stopped (with 50 to 55.5 mM 2-bromoethanesulfonate). Addition of a eubacterial inhibitor (vancomycin, 100 mg/liter) greatly reduced …

Gravity Wave-Driven Fluctuations In Oh Nightglow From An Extended, Dissipative Emission Region, G. Schubert, R. L. Walterscheid, Michael P. Hickey Ph.D.

Publications

The theory of gravity wave-driven fluctuations in the OH nightglow from an extended source region is generalized to account for effects of eddy kinematic viscosity ν and eddy thermal diffusivity κ. In the nondiffusive case, the amplitudes and phases of vertically integrated normalized intensity 〈δI〉/〈Ī〉 and temperature 〈δTI〉/〈ĪI〉perturbations and vertically integrated Krassovsky's ratio 〈η〉 as functions of period are influenced by the upper limit of vertical integration of the extended source, especially at long periods when vertical wavelengths λᵥ are small. The effects, which include oscillations in 〈δT〉/〈Ī〉 , and 〈η〉, particularly at long …

The Luminosities Of Bright H N Regions In Ngc 628 And Its O Star Formation Rate, Ted Von Hippel, Greg Bothun

Publications

Using narrow band CCD imaging we have identified 183 bright H n regions in the Sc galaxy NGC 628. These H n regions have luminosities which indicate that they are powered by young star clusters which contain ^ 100 ionizing stars. We attempt to reproduce the H ii region LF with and without models including stellar evolution. We find stellar evolution an important parameter in understanding the H n region LF and find that it allows star-forming galaxies to be more robust to star bursting episodes. Ranking the H n regions by luminosity and assuming that luminosity evolution is due …

A Simulation And Diagnostic Study Of Water Vapor Image Dry Bands, Bradley M. Muller, Henry E. Fuelberg

Publications

A Limited Area Mesoscale Prediction System (LAMPS) model simulation and special 3-hour radiosonde dataset are used to investigate warm (dry) bands in 6,7 μm water vapor satellite imagery on 6–7 March 1982. The purpose is to reveal processes resulting in the formation and evolution of the dry features that appear as curving dark streaks in the imagery. Model soundings are input to a radiative transfer algorithm to generate synthetic 6.7 μm equivalent blackbody temperatures (TB) which are compared with those from the Visible infrared Spin Scan Radiometer Atmospheric Sounder aboard the Geostationary Operational Environmental Satellite. Simulated and radiosonde-derived vertical velocity …

Biological Reductive Dechlorination Of Tetrachloroethylene And Trichloroethylene To Ethylene Under Methanogenic Conditions, David L. Freedman, James M. Gossett

Publications

A biological process for remediation of groundwater contaminated with tetrachloroethylene (PCE) and trichloroethylene (TCE) can only be applied if the transformation products are environmentally acceptable. Studies with enrichment cultures of PCE- and TCE-degrading microorganisms provide evidence that, under methanogenic conditions, mixed cultures are able to completely dechlorinate PCE and TCE to ethylene, a product which is environmentally acceptable. Radiotracer studies with [14C]PCE indicated that [14C]ethylene was the terminal product; significant conversion to 14CO2 or 14CH4 was not observed. The rate-limiting step in the pathway appeared to be conversion of vinyl chloride to ethylene. To sustain reductive dechlorination of PCE and …

A Working Catalogue Of Herbig Haro Objects, Ted Von Hippel, S.J. Bell Burnell, P.M. Williams

Publications

We present a catalogue of 184 Herbig Haro objects from a literature search complete to 1987.5. It is intended to update the 1974 catalogue of Herbig. The catalogue contains accurate co-ordinates, proper motions, radial velocities and spectral information for these objects. A cross-reference to the two best finding charts is included. A grouping of Herbig Haro objects into is also listed.

Effects Of Eddy Viscosity And Thermal Conduction And Coriolis Force In The Dynamics Of Gravity Wave Driven Fluctuations In The Oh Nightglow, Michael P. Hickey Ph.D.

Publications

Recently, Walterscheid et al. (1987) have described a dynamical-chemical model of wave-driven fluctuations in the OH nightglow which incorporated a five-reaction photochemical scheme and the dynamics of linearized acoustic-gravity waves in an isothermal, motionless atmosphere. The intensity oscillation (δI) about the time-averaged intensity (I0) and the temperature oscillation (δT) about the time-averaged temperature (T0) were related by means of the complex ratio η ≡ (δI/I0)/(δT/T0). One of the main conclusions of their work was that the inclusion of dynamical effects is absolutely essential for …

Wavelength Dependence Of Eddy Dissipation And Coriolis Force In The Dynamics Of Gravity Wave Driven Fluctuations In The Oh Nightglow, Michael P. Hickey Ph.D.

Publications

The theory of Walterscheid et al. (1987) to explain internal gravity wave induced oscillations in the emission intensity I and rotational temperature T of the OH nightglow was modified by Hickey (1988) to include the effects of eddy dissipation and Coriolis force. In the theory of Walterscheid et al. (1987) the ratio η = (δI/I0)/(δT/T0) (δ refers to a perturbation quantity, and a zero subscript refers to an average) was found to be independent of horizontal wavelength at long periods, while in the extended theory of Hickey (1988) some such dependence was …

Earth Observing System, Volume Iia: Data And Information System, Report Of The Eos Data Panel, Raymond Arvidson, Frederick Billingsley, Robert Chase, Pat Chavez Jr., Michael Devirian, Frederick Mosher, Et Al.

Publications

The purpose of this report is to provide NASA with a rationale and recommendations for planning, implementing, and operating an Earth Observing System data and information system that can evolve to meet the Earth Observing System's needs in the 1990s. The Earth Observing System (EOS), defined by the EOS Science and Mission Requirements Working Group, consists of a suite of instruments in low Earth orbit acquiring measurements of the Earth's atmosphere, surface, and interior; an information system to support scientific research; and a vigorous program of scientific research, stressing study of global-scale processes that shape and influence the Earth as …

Periods Of Eo And Fv Comae Berenices And The Functional Forms Of Their O-C Diagrams, Mark Anthony Reynolds

Publications

New elements are given for the RRab Lyrae variables EO Comae Berenices and FV Comae Berenices. The statistical significance of higher order terms in a polynomial least squares fit is discussed.

The Frontal Hydraulic Head: A Micro-Α Scale (~1 Km) Triggering Mechanism For Mesoconvective Weather Systems, M. A. Shapiro, Tamara Hampel, Doris Rotzoll, F. Mosher

Publications

Measurements from the NOAA Boulder Atmospheric Observatory (BAO) 300 m tower, the National Center for Atmospheric Research (NCAR) Sabreliner aircraft, and the NOAA GOES-5 satellite, give evidence for the cross-front scale collapse of nonprecipitating surface cold-frontal zones to horizontal distances of ∼1 km or less. The leading edges of these frosts possess the characteristic structure of density current flows: an elevated hydraulic head followed by a turbulent wake. Vertical motions at the frontal heads exceed 5 m s−1 at 300 m (AGL). The ascent at the frontal head may act as a (∼1 km-scale) triggering mechanism for the release of …

Lessons Learned From The Csis [Centralized Storm Information System] (Appendix D), Frederick R. Mosher, Joseph T. Schaefer

Publications

Various attempts have been made to give up-to-the-minute meteorological observations to forecasters. However, the meteorologist's inability to assimilate all the real-time data is a significant barrier to the improvement of short-term forecasts and warnings. Historically, failure to resolve this problem has plagued mesoscale forecast experiments. This article discusses the joint effort of NWS, NESS, NASA, and SSEC to develop a system to aid the forecaster in evaluating data.

Impacts Of Interactive Processing Systems On The Forecasting Ability Of The National Severe Storms Forecast Center (Appendix E), Frederick R. Mosher

Publications

The National Severe Storms Forecast Center (NSSFC) in Kansas City has the most modern interactive processing equipment of any operational forecast office in the United States. As such, the experiences of the NSSFC serve as the indication of some of the benefits which will be derived from interactive technology when it is applied in other forecast situations. The forecast products issued by the NSSFC have become more accurate and more timely. The forecaster's efficiency and productivity has noticeably improved. These improvements have been made without the introduction of any new data sources, any major advances in meteorology, or any major …

Functional And Performance Requirements Of The Next Noaa-Kansas City Computer System (Appendix G), Frederick R. Mosher

Publications

The NOAA computer system in Kansas City, Missouri, was scheduled for a computer upgrade and this is part of the report listing the critical functional and performance requirements for that system in 1984. The system needed to communicate with all the other offices at that center in Kansas City.

Characteristics Of Water Vapor Tracked Winds, Frederick R. Mosher

Publications

Wind measurements were obtained by tracking water vapor features on Meteosat and GOES-VAS 6.7 micron water vapor images. While pure water vapor features are fuzzy, there are discernible features which can be tracked. An investigation of preprocessing algorithms designed to bring out the features to be tracked showed that high pass filters tended to bring out the noise in the image, while low pass filters washed out the features. Sliced linear gray scale stretching under operator control gave the best enhancement to the water vapor features.

Meteorological Significance Of Cloud Tracked Winds During Dst-5 And Dst-6, H. M. Goodman, Frederick Mosher, Tod Stewart, Verner Suomi

Publications

A study has been conducted to determine the meteorological significance of satellite derived cloud drift winds using data from the Data Systems Test (DST). Three synoptic weather events were chosen during DST-6 (January 5-March 5) for weather analysis and comparison. The three events each contained a prominent weather feature over the north Pacific Ocean. Two satellite sources (NESS and the University of Wisconsin), radiosonde and commercial aircraft reports combined to produce a wind set covering the target area.

A Model For Calculating Desert Aerosol Turbidity Over The Oceans From Geostationary Satellite Data, Carl C. Norton, Frederick R. Mosher, Barry Hinton, David W. Martin, David Santek, William Kuhlow

Publications

A technique has been developed to infer the optical thickness of Saharan dust from Synchronous Meteorological Satellite (SMS) brightness measurements at visible wavelengths. The scattering model consists of an air layer, a dust layer and a lower boundary of variable albedo. Single-scatter properties of the dust computed from Mie theory were the basis for calculations by plane-parallel theory of radiative transfer in the dust layer. Radiative interactions between air and dust layers and the lower boundary were calculated with an adding version of the doubling scheme. Optical thickness was determined from satellite brightness measurements through a lookup table produced by …

Shallow Convection On Day 261 Of Gate: Mesoscale Arcs, C. Warner, J. Simpson, D. W. Martin, D. Suchman, F. R. Mosher, R. F. Reinking

Publications

On 18 September 1974, a cloud cluster growing in the GATE [Global Atmospheric Research Program] ship array was examined using aircraft flying close to one another at different heights, the geostationary satellite SMS-1, and radar, rawinsonde and ship data, with a view to elucidating mechanisms of convection. In this paper we concentrate analysis on cloudy convection in the moist layer.

In and above southerly surface monsoon flow approaching the cluster, clouds indigenous to the moist layer took the form of rows of tiny cumulus, and of arcs of cumulus mediocris, with patterns different from those of deeper clouds. From satellite …