Engineering topics

Lochner, James C.

Publications and source records attributed to Lochner, James C..

9 records

NASA NTRS2007

Motivating Reluctant Learners with a Big Bang

We present results of a collaboration between a media specialist, a science teacher, and an astronomer to bring a modern astronomy topic to at-risk, emotionally disabled students who have experienced little success. These normally unengaged students became highly motivated because they were given an authentic task of presenting research on an intriguing science topic, and because they witnessed a collaboration brought together on their behalf This experience demonstrates that sophisticated astronomy topics can be used to motivate at-risk students.

Lochner, James C.↗

NASA NTRS2002

The Imagine the Universe! E/PO Program

Since 1996, the Imagine the Universe! E/PO program has brought information and curriculum support materials to upper middle school, high school, and lower undergraduate students and their teachers on topics in the Structure and Evolution of the Universe (SEU) theme. The Imagine E/PO program consists of a web site, a series of posters and information/activity booklets, and a repertoire of educator workshops. We involve both scientists and educators in the development and testing of the materials. We describe here the various aspects of this program.

Lochner, James C.↗

NASA NTRS2000

Imagine the Universe: The Hidden Lives of Galaxies

Welcome to the fourth in a series of posters and activity booklets produced in conjunction with the Imagine the Universe! web site. The poster/booklet sets are intended to provide additional curriculum support materials for some of the subjects presented in the web site. The information provided for the educator in the booklet is meant to give the necessary background information so that the topic can be taught confidently to the students. The activities can be used to engage and excite students about the topic of galaxies in a number of disciplines and ways. The booklet and all activities can be photocopied and distributed for educational, non-commercial purposes.

Lochner, James C.↗

NASA NTRS1998

Imagine the Universe!

Imagine the Universe! gives students, teachers, and the general public a window on how high-energy astrophysics is used to probe the structure and evolution of the Universe. This is the universe as revealed by X-rays, gamma-rays and cosmic rays. Information about this exciting branch of astronomy is available in Imagine the Universe! at a variety of reading levels, and is illustrated with on-line graphics, animations, and movies. Information is presented on topics ranging from the Sun to black holes to X-ray and gamma-ray satellites. Imagine! also features a Teacher's Corner with study guides, lesson plans, and information on other education resources. Further descriptions of features of the Imagine! site and the other sites included on the CD-ROM may be found in sections V and VI of the booklet file.

Whitlock, Laura A.↗

NASA NTRS1994

Observations of the Small Magellanic Cloud by the Vela 5B X-ray monitor

We present Vela 5B observations of the Small Magellanic Cloud (SMC) region obtained during the years 1969 - 1979. We detect the 3.89 day orbital modulation of SMC X-1 with a false alarm probability of 4.3 x 10(exp -3) and observe a high state beginning in 1970 September and lasting approximately 100 days. We also detect three outbursts by a transient source consistent with the position of the candidate Be-neutron star system H0107-750 (= 1H 0103-762). These events occur roughly 100 days apart and last for approximately 35 days. No detections of SMC X-2 or SMC X-3 are apparent above a limit of approximately 7 x 10(exp 37) ergs/s.

Whitlock, L.↗

NASA NTRS1994

Recurrence times and periodicities in 4U 1608-52 as observed by Vela 5B

We report on the Vela 5B 10 year history of the soft X-ray transient 4U 1608-52, and on the characteristics of its soft X-ray outbursts. The Vela 5B satellite observed the four known outbursts in 1975, 1977, and 1979, and four new outbursts in 1970 and 1971, altering the recurrence pattern of outbursts from this source. One of the 1970 outbursts is symmetric in its intensity profile, while the two outbursts in 1971 have short exponential profiles separated by 80 days. Despite suggestive recurrence periods of approximately 85 and approximately 150 days evident in the time intervals between the outbursts, there is no single statistically significant recurrence time on which the outbursts recur consistently. In the 1970 symmetric event, there is evidence for a period of either 4.10 or 5.19 days. Drawing upon the analogy with SU Ursa Majoris dwarf novae, we suggest that the short period is orbital and any longer period would be associated with a precession period of the accretion disk.

Lochner, James C.↗

NASA NTRS1992

Long-term variability in low-mass X-ray binaries - A study using data from Vela 5B

A complete sample of low-mass X-ray binaries in uncrowded fields obtained from Vela 5B is studied here for periodic and aperiodic time variability on time scales of more than one day. The strong 176-day periodicity in X1820 - 303 is confirmed, and evidence is found for a significant 77-day period in Cyg X-2 and for variability on time scales of less than about 200 days in Cyg X-3. Limits are set on the possible amplitude of candidate periodicities in the literature for Ser X-1 and X0614 + 091. The evidence reported here suggests that while long-term cyclic variability is common among high-mass binaries, it is a rare occurrence in low-mass systems.

Smale, Alan P.↗

NASA NTRS1991

Shot model parameters for Cygnus X-1 through phase portrait fitting

Shot models for systems having about 1/f power density spectrum are developed by utilizing a distribution of shot durations. Parameters of the distribution are determined by fitting the power spectrum either with analytic forms for the spectrum of a shot model with a given shot profile, or with the spectrum derived from numerical realizations of trial shot models. The shot fraction is specified by fitting the phase portrait, which is a plot of intensity at a given time versus intensity at a delayed time and in principle is sensitive to different shot profiles. These techniques have been extensively applied to the X-ray variability of Cygnus X-1, using HEAO 1 A-2 and an Exosat ME observation. The power spectra suggest models having characteristic shot durations lasting from milliseconds to a few seconds, while the phase portrait fits give shot fractions of about 50 percent. Best fits to the portraits are obtained if the amplitude of the shot is a power-law function of the duration of the shot. These fits prefer shots having a symmetric exponential rise and decay. Results are interpreted in terms of a distribution of magnetic flares in the accretion disk.

Lochner, James C.↗

NASA NTRS1989

A search for a dynamical attractor in Cygnus X-1

A method used for searching for low-dimensional attractors in fluctuating signals is applied to the aperiodicity observed in Cyg X-1. The analysis technique for determining the dimension of an attractor given its light curve, and the practical limitations in applying the technique, are described. The requirement of large amounts of low-noise data is found to be very important in using the technique. No low-dimensional attractor is found for the set of Cyg X-1 data used, but evidence of an attractor with large dimension may be present.

Lochner, James C.↗