Bearing Signal Separation of Commercial Helicopter Main Gearbox

Gears are significant component in a multiplicity of industrial applications such as machine tool and gearboxes. An unforeseen failure of gear may result in significant economic losses. Therefore this research propose fault detection improvement throught series of vibration signal processing techuiques. These techniques have been tested experimentally using vibration data collected from the transmission system of a CS-29 ‘Category A’ helicopter gearbox under different bearing damage severity of the second planetary stage. Results showed successful improvement of bearing fault detection

Helicopter gearbox bearing fault detection using separation techniques and envelope analysis

The main gearbox (MGB) is a crucial part of a helicopter. MGB bearings suffer intensively from stress and friction during flights hence concerns for their health condition and detecting potential defects become critical for the sake of operation safety and system reliability. In this study, bearing defects were seeded in the second epicyclic stage bearing of a commercial Class A helicopter MGB. Vibration and tachometer signals were recorded simultaneously for the purpose of fault diagnosis. The tests were carried out at different power and speed conditions for various seeded bearing defects. This paper presents a comparison of signal processing techniques employed to identify the presence of the defects masked by strong background noise generated from an operation helicopter MGB

Sub-millimeter images of a dusty Kuiper belt around eta Corvi

We present sub-millimeter and mid-infrared images of the circumstellar disk around the nearby F2V star eta Corvi. The disk is resolved at 850um with a size of ~100AU. At 450um the emission is found to be extended at all position angles, with significant elongation along a position angle of 130+-10deg; at the highest resolution (9.3") this emission is resolved into two peaks which are to within the uncertainties offset symmetrically from the star at 100AU projected separation. Modeling the appearance of emission from a narrow ring in the sub-mm images shows the observed structure cannot be caused by an edge-on or face-on axisymmetric ring; the observations are consistent with a ring of radius 150+-20AU seen at 45+-25deg inclination. More face-on orientations are possible if the dust distribution includes two clumps similar to Vega; we show how such a clumpy structure could arise from the migration over 25Myr of a Neptune mass planet from 80-105AU. The inner 100AU of the system appears relatively empty of sub-mm emitting dust, indicating that this region may have been cleared by the formation of planets, but the disk emission spectrum shows that IRAS detected an additional hot component with a characteristic temperature of 370+-60K (implying a distance of 1-2AU). At 11.9um we found the emission to be unresolved with no background sources which could be contaminating the fluxes measured by IRAS. The age of this star is estimated to be ~1Gyr. It is very unusual for such an old main sequence star to exhibit significant mid-IR emission. The proximity of this source makes it a perfect candidate for further study from optical to mm wavelengths to determine the distribution of its dust.Comment: 22 pages, 4 figures. Scheduled for publication in ApJ 10 February 2005 issu

Discovery of the Fomalhaut C debris disc

Fomalhaut is one of the most interesting and well studied nearby stars, hosting at least one planet, a spectacular debris ring, and two distant low-mass stellar companions (TW PsA and LP 876-10, a.k.a. Fomalhaut B & C). We observed both companions with Herschel, and while no disc was detected around the secondary, TW PsA, we have discovered the second debris disc in the Fomalhaut system, around LP 876-10. This detection is only the second case of two debris discs seen in a multiple system, both of which are relatively wide ($\gtrsim$3000 AU for HD 223352/40 and 158 kAU [0.77 pc] for Fomalhaut/LP 876-10). The disc is cool (24K) and relatively bright, with a fractional luminosity $L_{\rm disc}/L_\star = 1.2 \times 10^{-4}$, and represents the rare observation of a debris disc around an M dwarf. Further work should attempt to find if the presence of two discs in the Fomalhaut system is coincidental, perhaps simply due to the relatively young system age of 440 Myr, or if the stellar components have dynamically interacted and the system is even more complex than it currently appears.Comment: Published in MNRAS Letters. Merry Xma

Mössbauer spectroscopic study of some iron and antimony – containing minerals

Iron-57 Mössbauer spectra have been recorded from three minerals containing both iron and antimony. Schafarzikite of composition FeSb2O4 contains Fe2+. The 121Sb Mössbauer spectrum shows only the presence of Sb3+. The 57Fe Mössbauer spectrum corresponds with that recorded from a material of identical composition synthesised by a solid state reaction during the course of this work. Apuanite of formulation Fe20Sb16O48S4 contains both Fe2+ Fe3+ in the ratio 1:3.35 The result is consistent with crystal structure determinations and the formulation of apuanite as Fe42+Fe163+Sb16O48S4. Versiliaite of composition Fe12Sb12O32S2 contains Fe2+and Fe3+ in the ratio 1:2.12 and, also consistent with structural characterisations, can be formulated Fe42+Fe83+Sb123+O32S2

JC and BK virus sequences are not detectable in leukaemic samples from children with common acute lymphoblastic leukaemia

Epidemiological evidence suggests that childhood leukaemia, and possibly common acute lymphoblastic leukaemia in particular, may have an infectious aetiology. Smith (1997 J Immunother20: 89–100) recently suggested that the critical infectious event occurs during pregnancy, and identified the polyoma virus JC as a candidate agent. In the present study we investigated whether genomes from the JC virus, and closely related BK virus, could be detected in leukaemic cells. No positive results were obtained suggesting that JC virus is unlikely to play a direct role in leukaemogenesis. © 1999 Cancer Research Campaig