The Solar Neighborhood XV: Discovery of New High Proper Motion Stars with mu >= 0.4"/yr between Declinations -47 degrees and 00 degrees

We report the discovery of 152 new high proper motion systems (mu >= 0.4"/yr) in the southern sky (Declination = -47 degrees to 00 degrees) brighter than UKST plate R_{59F} =16.5 via our SuperCOSMOS-RECONS (SCR) search. This paper complements Paper XII in The Solar Neighborhood series, which covered the region from Declination = -90 degrees to -47 degrees and discussed all 147 new systems from the southernmost phase of the search. Among the total of 299 systems from both papers, there are 148 (71 in Paper XII, 77 in this paper) new systems moving faster than 0.5"/yr that are additions to the classic ``LHS'' (Luyten Half Second) sample. These constitute an 8% increase in the sample of all stellar systems with mu >= 0.5"/yr in the southern sky. As in Paper XII, distance estimates are provided for the systems reported here based upon a combination of photographic plate magnitudes and 2MASS photometry, assuming all stars are on the main sequence. Two SCR systems from the portion of the sky included in this paper are anticipated to be within 10 pc, and an additional 23 are within 25 pc. In total, the results presented in Paper XII and here for this SCR sweep of the entire southern sky include five new systems within 10 pc and 38 more between 10 and 25 pc. The largest number of nearby systems have been found in the slowest proper motion bin, 0.6"/yr > mu >= 0.4"/yr, indicating that there may be a large population of low proper motion systems very near the Sun.Comment: 36 pages, 5 figures, accepted for publication in Astronomical Journa

The Solar Neighborhood XII: Discovery of New High Proper Motion Stars with 1.0"/yr > mu >= 0.4"/yr between Declinations -90 degrees and -47 degrees

We report the discovery of 141 new high proper motion systems (1.0"/yr > mu >= 0.4"/yr) in the southern sky (Declination = -90 degrees to -47 degrees) brighter than UKST plate R_{59F} = 16.5 via our SuperCOSMOS-RECONS (SCR) search. When combined with the nine systems having mu >= 1.0"/yr and/or late spectral type from the initial phases of this effort (Hambly et al. 2004, Henry et al. 2004), we find that 73 of the 150 total systems are moving faster than 0.5"/yr, and are therefore new members of the classic "LHS" (Luyten Half Second) sample. These constitute a 21% increase in the sample of stars with mu >= 0.5"/yr in the declination region searched, thereby comprising an important addition to this long-neglected region of the sky. Distance estimates are provided for the entire sample, based upon a combination of photographic plate magnitudes and 2MASS photometry, using the relations presented in Hambly et al. (2004) for the presumed main sequence stars. Three systems are anticipated to be within 10 pc, and an additional 15 are within 25 pc. Eight of these 18 nearby systems have proper motions falling between 0.4"/yr and 0.6"/yr, hinting at a large population of nearby stars with fast, but not extremely high, proper motions that have not been thoroughly investigated.Comment: 45 pages, 6 figures, accepted for publication in Astronomical Journal (January 2005

Powder diffraction in the range of milliseconds

Powder diffraction studies with synchrotron radiation were performed on a time scale down to 2.5 ms at the HASYLAB beamline B2 with a commercial 1024 pixel linear photodiode-array detector system (OMA III, EG&G-PARC). The flux rate of 2 x 108 photons s-1 at a wavelength of 1.26 Å achieved by using a toroidal mirror and a standard double-crystal Si(111) monochromator was measured with an ionization chamber at the focus. With a synthetic multilayer to select the desired wavelength instead of the standard monochromator, a flux rate of 1.5 x 1010 photons s-1 was measured at a wavelength of 1.31 Å. The shortest possible recording times for a complete powder pattern of calcium fluoride were 200 ms with the crystal monochromator and 2.5 ms with the multilayer. The angular resolution for both cases is discussed. The high-speed data collection was successfully applied with the double-crystal and multilayer monochromators to the recording of more-complex patterns and to monitor a phase transformation in order to demonstrate the feasibility of kinetic studies on the millisecond time scale

Rotor Model Updating and Validation for an Active Magnetic Bearing Based High-Speed Machining Spindle

This paper presents an experimentally driven model updating approach to address the dynamic inaccuracy of the nominal finite element (FE) rotor model of a machining spindle supported on active magnetic bearings. Modeling error is minimized through the application of a numerical optimization algorithm to adjust appropriately selected FE model parameters. Minimizing the error of both resonance and antiresonance frequencies simultaneously accounts for rotor natural frequencies as well as for their mode shapes. Antiresonance frequencies, which are shown to heavily influence the model’s dynamic properties, are commonly disregarded in structural modeling. Evaluation of the updated rotor model is performed through comparison of transfer functions measured at the cutting tool plane, which are independent of the experimental transfer function data used in model updating procedures. Final model validation is carried out with successful implementation of robust controller, which substantiates the effectiveness of the model updating methodology for model correction

Detecting Cracked Rotors Using Auxiliary Harmonic Excitation

Cracked rotors are not only important from a practical and economic viewpoint, they also exhibit interesting dynamics. This paper investigates the modelling and analysis of machines with breathing cracks, which open and close due to the self-weight of the rotor, producing a parametric excitation. After reviewing the modelling of cracked rotors, the paper analyses the use of auxiliary excitation of the shaft, often implemented using active magnetic bearings to detect cracks. Applying a sinusoidal excitation generates response frequencies that are combinations of the rotor spin speed and excitation frequency. Previously this system was analysed using multiple scales analysis; this paper suggests an alternative approach based on the harmonic balance method, and validates this approach using simulated and experimental results. Consideration is also given to some issues to enable this approach to become a robust condition monitoring technique for cracked shafts

Demonstration Advanced Avionics System (DAAS) function description

The Demonstration Advanced Avionics System, DAAS, is an integrated avionics system utilizing microprocessor technologies, data busing, and shared displays for demonstrating the potential of these technologies in improving the safety and utility of general aviation operations in the late 1980's and beyond. Major hardware elements of the DAAS include a functionally distributed microcomputer complex, an integrated data control center, an electronic horizontal situation indicator, and a radio adaptor unit. All processing and display resources are interconnected by an IEEE-488 bus in order to enhance the overall system effectiveness, reliability, modularity and maintainability. A detail description of the DAAS architecture, the DAAS hardware, and the DAAS functions is presented. The system is designed for installation and flight test in a NASA Cessna 402-B aircraft