Flight testing the fixed-wing configuration of the Rotor Systems Research Aircraft (RSRA)

The Rotor Systems Research Aircraft (RSRA) is a unique research aircraft designed to flight test advanced helicopter rotor system. Its principal flight test configuration is as a compound helicopter. The fixed wing configuration of the RSRA was primarily considered an energy fly-home mode in the event it became necessary to sever an unstable rotor system in flight. While it had always been planned to flight test the fixed wing configuration, the selection of the RSRA as the flight test bed for the X-wing rotor accelerated this schedule. This paper discusses the build-up to, and the test of, the RSRA fixed wing configuration. It is written primarily from the test pilot's perspective

Some recursive formulas for Selberg-type integrals

A set of recursive relations satisfied by Selberg-type integrals involving monomial symmetric polynomials are derived, generalizing previously known results. These formulas provide a well-defined algorithm for computing Selberg-Schur integrals whenever the Kostka numbers relating Schur functions and the corresponding monomial polynomials are explicitly known. We illustrate the usefulness of our results discussing some interesting examples.Comment: 11 pages. To appear in Jour. Phys.

The Spectra and Variability of X-ray Sources in a Deep Chandra Observation of the Galactic Center

We examine the X-ray spectra and variability of the sample of X-ray sources with L_X = 10^{31}-10^{33} erg s^{-1} identified within the inner 9' of the Galaxy. Very few of the sources exhibit intra-day or inter-month variations. We find that the spectra of the point sources near the Galactic center are very hard between 2--8 keV, even after accounting for absorption. When modeled as power laws the median photon index is Gamma=0.7, while when modeled as thermal plasma we can only obtain lower limits to the temperature of kT>8 keV. The combined spectra of the point sources is similarly hard, with a photon index of Gamma=0.8. Strong line emission is observed from low-ionization, He-like, and H-like Fe, both in the average spectra and in the brightest individual sources. The line ratios of the highly-ionized Fe in the average spectra are consistent with emission from a plasma in thermal equilibrium. This line emission is observed whether average spectra are examined as a function of the count rate from the source, or as a function of the hardness ratios of individual sources. This suggests that the hardness of the spectra may in fact to due local absorption that partially-covers the X-ray emitting regions in the Galactic center systems. We suggest that most of these sources are intermediate polars, which (1) often exhibit hard spectra with prominent Fe lines, (2) rarely exhibit either flares on short time scales or changes in their mean X-ray flux on long time scales, and (3) are the most numerous hard X-ray sources with comparable luminosities in the Galaxy.Comment: 27 pages, including 13 figures. To appear in ApJ, 1 October 2004, v613 issue. An electronic version of table 2 is on http://astro.ucla.edu/~mmuno/sgra/table2_electronic.txt and reduced data files for each source are available on http://www.astro.psu.edu/users/niel/galcen-xray-data/galcen-xray-data.htm

The H1 Forward Track Detector at HERA II

In order to maintain efficient tracking in the forward region of H1 after the luminosity upgrade of the HERA machine, the H1 Forward Track Detector was also upgraded. While much of the original software and techniques used for the HERA I phase could be reused, the software for pattern recognition was completely rewritten. This, along with several other improvements in hit finding and high-level track reconstruction, are described in detail together with a summary of the performance of the detector.Comment: Minor revision requested by journal (JINST) edito

A numerical investigation on the vortex formation and flow separation of the oscillatory flow in jet pumps

A two-dimensional computational fluid dynamics model is used to predict the oscillatory flow through a tapered cylindrical tube section (jet pump) placed in a larger outer tube. Due to the shape of the jet pump, there will exist an asymmetry in the hydrodynamic end effects which will cause a time-averaged pressure drop to occur that can be used to cancel Gedeon streaming in a closed-loop thermoacoustic device. The performance of two jet pump geometries with different taper angles is investigated. A specific time-domain impedance boundary condition is implemented in order to simulate traveling acoustic wave conditions. It is shown that by scaling the acoustic displacement amplitude to the jet pump dimensions, similar minor losses are observed independent of the jet pump geometry. Four different flow regimes are distinguished and the observed flow phenomena are related to the jet pump performance. The simulated jet pump performance is compared to an existing quasi-steady approximation which is shown to only be valid for small displacement amplitudes compared to the jet pump length.Comment: The following article has been accepted by the Journal of the Acoustical Society of America. After it is published, it will be found at: http://scitation.aip.org/JAS

Speech Analysis

Contains reports on two research projects

Application of Tomography to the Nuclear Industry

While tomographic methods of reconstructing three~dimensional x-ray images are becoming more common in the medical field, their application to industrial problems has only started. Some of the features that differentiate industrial tomography from medical tomography are x-ray energies may vary from\u3c 10 keV to\u3e 22 MeV radiation dose to the object is not a constraint inspection times (within economic constraints) are not as important the anomalies to be detected offer sharp, high contrast boundaries to the inspection system high spatial resolution rather than high contrast sensitivity is the primary design goal, and the number of views may be limited by other (mechanical) constraints. This paper will describe the effort the Los Alamos Scientific Laboratory (LASL) is making to define the design parameters that affect the constraints listed above. A tomographic test bed in which various design features may be evaluated will be described. The computational facilities at LASL, which include a versatile modeling code that can simulate tomographic systems with various types of radiation, geometries, and detector types, will also be discussed

Effect of a Platinum Chemotherapy Drug on Intracellular Elements During the Cell Cycle, Using X-Ray Microanalysis

Intracellular elemental concentrations were measured in the cytoplasm, nucleus and nucleolus of cultured Chinese hamster ovary (CHO) cells, using energy dispersive electron probe X-ray microanalysis and transmission electron microscopy. Synchronous CHO cell populations were analyzed at different times during the growth cycle. The elements K, P, Mg and Zn were all more concentrated in the nucleus and nucleolus than in the cytoplasm, while no specific subcellular compartmentalization was evident for the elements Na, Cl, Ca, Fe and S. Significant changes in intracellular elemental concentrations were associated with the progression of cells from G1 phase to S phase of the growth cycle. Most significant were the effects on the monovalent ions, Na, K and Cl. The effect of a second generation platinum chemotherapy agent, cis-dichloro-bis (isopropylamine) trans-dihydroxy platinum IV (iproplatin) on intracellular elements was investigated by analyzing subcellular compartments of drug-treated synchronous CHO cell populations. Changes in intracellular elemental levels occurred, most notably in the nucleus of G1 phase cells, when a general depletion of most essential elements was evident. Attempts to analyze cells for their Pt content proved disappointing, since quantitation for Pt was not possible. However, measurement of Pt peak/background ratio yielded significant Pt peaks on analyzing lysosomes of cells treated with high concentrations of iproplatin. These Pt peaks were associated with high levels of S and Fe

Anarchism, individualism and communism: William Morris's critique of anarcho-communism

This collection of essays, showing how the boundaries between Marxism and anarchism have been more porous and fruitful than is conventionally recognised, charts a history of radical socialist collaborations from the late 19th ..