Space Telescope Imaging Spectrograph Parallel Observations of the Planetary Nebula M94-20

The planetary nebula M94--20 in the Large Magellanic Cloud was serendipitously observed with the Space Telescope Imaging Spectrograph on board the Hubble Space Telescope as part of the Hubble Space Telescope Archival Pure Parallel Program. We present spatially resolved imaging and spectral data of the nebula and compare them with ground based data, including detection of several emission lines from the nebula and the detection of the central star. We find the total H alpha + [NII] flux = 7.3e-15 erg s^-1 cm^-2 and we estimate the magnitude of the central star to be m_V = 26.0 +/- 0.2. Many other H alpha sources have been found in M31, M33 and NGC 205 as well. We discuss the use of the parallel observations as a versatile tool for planetary nebula surveys and for other fields of astronomical research.Comment: Latex, 14 pages, 2 JPEG figures, 2 tables. PASP Research Note, June 1999, in pres

A High-Speed X-Ray Detector System for Noninvasive Fluid Flow Measurements

The opaque nature of many multiphase flows has long posed a significant challenge to the visualization and measurement of desired characteristics. To overcome this difficulty, X-ray imaging, both in the form of radiography and computed tomography, has been used successfully to quantify various multiphase flow phenomena. However, the relatively low temporal resolution of typical X-ray systems limit their use to moderately slow flows and time-average values. This paper discusses the development of an X-ray detection system capable of high-speed radiographic imaging that can be used to visualize multiphase flows. Details of the hardware will be given and then applied to sample multiphase flows in which X-ray radiographic images of up to 1,000 frames per second were realized. The sample flows address two different multiphase flow arrangements. The first is a gas-liquid system representative of a small bubble column. The second is a gas-solid system typically found in a fluidized bed operation. Sample images are presented and potential challenges and solutions are discussed

Statistical analysis of focused beam radiographs taken from a coaxial airblast spray

Studying the near-field region of sprays is particularly challenging because it is optically dense. However, energy in the X-ray range is capable of penetrating this dense region and obtaining information that would otherwise be unavailable. Through time-resolved X-ray radiography, a better understanding of the near-field region is currently being developed. The 7-BM beamline at the Advanced Photon Source at Argonne National Lab was focused down to a 5 x 6 μm cross-sectional area. The attenuation in the beam, which is used to calculate the effective path length of liquid, was then collected at an effective rate of 270 kHz for 10 seconds. Various statistical measures were applied to the X-ray focused beam radiographs including average, standard deviation, skewness, and kurtosis, to quantify the spray from a canonical coaxial airblast nozzle. Results show that the average effective path length is useful in determining the intact length and spray angle. The capabilities of additional statistical measures in determining important spray characteristics are also discussed

Measurement of Liquid Core Length of a Coaxial Two-fluid Spray

Shadowgraphs, tube-source X-ray radiographs, and synchrotron X-ray radiographs from a coaxial two-fluid spray are analyzed to measure the liquid core length of the spray. Two flow conditions: Rel = 1,100, Reg = 21,300, We = 40, and Rel = 1,100, Reg = 46,700, We = 196 are investigated. The standard deviation of the fluctuating intensity values are calculated and analyzed to estimate the liquid core length. Additionally, the largest connected domain is used to find an instantaneous breakup position of the spray. The results show that the high standard deviation region is related to the ligament development region, and the instantaneous position identifies ligament formation in the spray

Optimization of High-Speed White Beam X-ray Imaging for Spray Characterization

The near-field region of a spray has a significant impact on the downstream dynamics. However, the near-field region remains one of the most difficult areas to characterize due to its optical density to visible light. One of the methods used to probe the near-field region is high-speed white beam (broad-spectrum) X-ray radiography, which generates path integrated, time sequenced images of the spray. While white beam imaging is effective at probing the near-field region, high intensity synchrotron sources are required to acquire high-speed time-resolved image sequences. The drawback to a synchrotron source is it emits a significant portion of its X-ray spectrum at energies that are minimally attenuated by most sprays. This paper will examine the various parameters that can be tuned to improve the characterization of sprays with white beam X-rays, and will assess their effects on the X-ray image quality. A representative spray conditions will be shown using a canonical coaxial gas-liquid atomizer imaged at the 7-BM beamline of the Advanced Photon Source at Argonne National Laboratory

Developing Tracer Particles for X-Ray Particle Tracking Velocimetry

X-ray imaging, as a noninvasive flow visualization technique, has been shown to be a useful method for observing and characterizing multiphase flows. One type of X-ray flow visualization technique, called X-ray Particle Tracking Velocimetry (XPTV), tracks an X-ray attenuating particle in an opaque fluid flow. A significant challenge with XPTV is identifying tracer particles with the desired fluid flow characteristics (e.g., small and neutrally buoyant) but yet differentially attenuate X-rays, which is based primarily on density differences. This paper describes the manufacturing of XPTV tracer particles that satisfy specific particle characteristics including high X-ray attenuation, uniform shape, specified effective density, and desired diameter. An example use of these particles as an intruder particle in a fluidized bed (to simulate biomass injection) is then demonstrated using X-ray stereographic imaging to determine intruder particle position as a function of time in a three-dimensional opaque system

Spatial dynamics in painting achieved through plane manipulation

In order to understand the thesis, a clear definition of terms is necessary. The idea of space as considered by the artist may consist of two concepts. One might deal with the greatly expanded space revealed in our contemporary action and thought. The other is definitely limited to the painting surface, whereon a small segment of a world, imagined or real, may be presented; or, the immensity of a universe boldly suggested. The modern painter can use pure space of controlled size (the painting surface), to create space of vast dimensions if he chooses. Or, as one critic, Aaron Berkman, says, "The canvas, too, is space. Within itself it is infinite; and the painter is a creator in the picture-space universe."

Quantitative genomics of locomotor behavior in Drosophila melanogaster

The locomotor behavior of Drosophila melanogaster was quantified in a large population of inbred lines derived from a single natural population, showing that many pleiotropic genes show correlated transcriptional responses to multiple behaviors