Structural analysis of hollow blades: Torsional stress analysis of hollow fan blades for aircraft jet engines

A torsional stress analysis of hollow fans blades by the finite element method is presented. The fans are considered to be double circular arc blades, hollowed 30 percent, and twisted by a component of the centrifugal force by the rated revolution. The effects of blade hollowing on strength and rigidity are discussed. The effects of reinforcing webs, placed in the hollowed section in varying numbers and locations, on torsional rigidity and the convergence of stresses, are reported. A forecast of the 30 percent hollowing against torsional loadings is discussed

Near-Solar-Circle Method for Determination of the Galactic Constants

We propose a method to determine the galactic constants R_0 (distance to the Galactic Center) and V_0 (rotation velocity of the Sun) from measurements of distances, radial velocities and proper motions of objects near the solar circle. This is a modification of the solar-circle method to a more practical observational method. We apply the method to determine R_0 using data from the literature with known distances and radial velocities, and obtain R_0 = 7.54 +/- 0.77 kpc.Comment: 5 pages, 4 figures, accepted for PASJ (Vol. 63 No. 5

Bipolar-Hyper-Shell Galactic Center Statrburst Model: Further Evidence from ROSAT Data and New Radio and X-ray Simulations

Using the all-sky ROSAT soft X-ray and 408-MHz radio continuum data, we show that the North Polar Spur and its western and southern counter-spurs draw a giant dumbbell-shape necked at the galactic plane. We interpret these features as due to a shock front originating from a starburst 15 million years ago with a total energy of the order of $\sim 10^{56}$ ergs or $10^5$ type II supernovae. We simulate all-sky distributions of radio continuum and soft X-ray intensities based on the bipolar-hyper-shell galactic center starburst model. The simulations can well reproduce the radio NPS and related spurs, as well as radio spurs in the tangential directions of spiral arms. Simulated X-ray maps in 0.25, 0.75 and 1.5 keV bands reproduce the ROSAT X-ray NPS, its western and southern counter-spurs, and the absorption layer along the galactic plane. We propose to use the ROSAT all-sky maps to probe the physics of gas in the halo-intergalactic interface, and to directly date and measure the energy of a recent Galactic Center starburst.Comment: To appear in ApJ, Latex MS in ApJ macro, 8 figures in jpg (original quality ps figs available on request

CO observations of galaxies with the Nobeyama 45-M telescope

High-resolution (15 inch), filled aperture maps of the CO (J = 1-0) line emission were obtained for several nearby, CO-bright galaxies like M82, M83, IC342, and NGC891 in order to study star forming activity in these galaxies

CO Observations of Luminous IR Galaxies at Intermediate Redshift

We present new measurement of $^{12}$CO($J=1-0$) emission from 16 luminous infrared galaxies (LIGs) at intermediate redshift ($cz \sim 10,000 - 50,000 {\rm km s^{-1}}$). These new data were selected by isolated and normal morphology. The CO observations were performed using the NRO 45-m telescope. Comparison of the CO and dust properties of the new result with those from other CO measurements revealed characteristics of this sample: (1) It is the deepest CO observations of IRAS galaxies at intermediate redshift without strong interaction features. (2) It has typical properties of normal IRAS galaxies in terms of star-formation efficiency, color-color diagrams and galactic nuclear activity. (3) It has smaller gas-to-dust ratio than normal IRAS galaxies. This can be explained by two-component dust model, and our sample consists of most of warm dust.Comment: To appear in PASJ, text 9 pages, 5 tables, and 12 figure

Optical and CO Radio Observations of Poor Cluster Zwicky 1615.8+3505

The cluster Zwicky 1615.8+3505 is considered to be a dynamically young poor cluster. To investigate the morphology and star-formation activity of galaxies under the environment of a dynamically young poor cluster, we have performed V, R, and I surface photometry, optical low-resolution spectroscopy, and 12CO (J=1-0) line observations for member galaxies. Our data show that more than 90% of the observed galaxies show regular morphologies and no star-formation activities, indicating that the environment does not affect these galaxy properties. Among sixteen galaxies observed, only NGC 6104 shows a significant star-formation activity, and shows a distorted morphology, indicating a tidal interaction. This galaxy contains double knots, and only one knot possesses Seyfert activity, though the sizes and luminosities are similar to each other; we also discuss this feature.Comment: LaTeX manuscript (text.tex, use PASJ style files), four PS figures (fig[a-d].ps), and three PASJ style files. text.tex, figb.ps, and figd.ps are up-dated. To be appeared in The Publications of the Astronomical Society of Japan, Vol. 51, No. 3 (1999 June issue

The Large-scale Bipolar Wind in the Galactic Center

During a 9-month campaign (1996--1997), the Midcourse Space Experiment (MSX) satellite mapped the Galactic Plane at mid-infrared wavelengths (4.3--21.3um). Here we report evidence for a spectacular limb- brightened, bipolar structure at the Galactic Center extending more than a degree (170 pc at 8.0 kpc) on either side of the plane. The 8.3um emission shows a tight correlation with the 3, 6 and 11 cm continuum structure over the same scales. Dense gas and dust are being entrained in a large-scale bipolar wind powered by a central starburst. The inferred energy injection at the source is ~10^54/kappa erg for which \kappa is the covering fraction of the dusty shell (kappa <= 0.1). There is observational evidence for a galactic wind on much larger scales, presumably from the same central source which produced the bipolar shell seen by MSX. Sofue has argued that the North Polar Spur -- a thermal x-ray/radio loop which extends from the Galactic Plane to b = +80 deg -- was powered by a nuclear explosion (1-30 x 10^55 erg) roughly 15 Myr ago. We demonstrate that an open-ended bipolar wind (~10^55 erg), when viewed in near-field projection, provides the most natural explanation for the observed loop structure. The ROSAT 1.5 keV diffuse x-ray map over the inner 45 deg provides compelling evidence for this interpretation. Since the faint bipolar emission would be very difficult to detect beyond the Galaxy, the phenomenon of large-scale galactic winds may be far more common than has been observed to date.Comment: 24 pages, 6 figures, aastex. High resolution figures are available at ftp://www.aao.gov.au/pub/local/jbh/astro-ph/GC/. Astrophysical Journal, accepte