1,721,097 research outputs found
Simultaneous determination of benzene and total aromatic fraction of gasoline by HPLC-DAD
No full text
Misura dei parametri necessari per la valutazione della probabilità di condensa superficiale ed interstiziale delle murature
No full textAn Active Control Device for Electric Power Plant
No full textThe large electric power generators are powered by diesel engines which produce very high noise levels, usually attenuated by passive mufflers systems, installed along the engines exhaust channels. In this paper, a new active noise control device is proposed, designed to be used in addition to the common passive mufflers ssystems, in order to achive a more elevated attenuation of noise. The device is made up by a box, which contains two power loudspeakers fed by a control circuit, that generates an electrical signal, teh spectral features of which are derived by picking up the electricity produced by the power generator. The acoustic signal emitted by the loudspeakers has the same shape but opposite phase of the signal produced by the engine. The two signals interfere across the final section of the engine exhaust pipe. The device has been installed on a power generator of a telephone exchange station: a noise reduction of about 20 dB was obtained. Furthermore, the mostly attenuated frequency range is 40-200 Hz, where the common passive mufflers systems show a very low efficiency
Young massive stars in the ISOGAL survey. I. VLA observations of the ISOGAL l=+45 field
No full textWe present VLA radio continuum observations at 3.6 and 6 cm of a ~ 0.65 sq. deg. field in the galactic plane at l=+45(deg) . These observations are meant to be used in a comparison with ISO observations at 7 and 15 mu m of the same region. In this paper we compare the radio results with other radio surveys and with the IRAS-PSC. At 3.6 and/or 6 cm we detect a total of 34 discrete sources, 13 of which are found in five separate extended complexes. These are all multiple or single extended thermal ultra-compact HII (UCHII) regions. While for each of these complexes an IRAS counterpart could be reliably found, no IRAS counterpart could be reliably identified for any of the remaining 21 sources. Of these 21 compact sources, six are candidate UCHII regions, and the other 15 are most probably background extragalactic non-thermal sources. The five IRAS sources associated with the radio continuum complexes all satisfy the \cite[Wood & Churchwell (1989a]{WC89}; WC89) color criteria for UCHII. None of the other 38 IRAS point sources present in our surveyed field show the same colors. This fraction of WC89 type to total IRAS sources is consistent with what is found over the entire galactic plane. The fact that, when observed with a compact VLA configuration, the IRAS sources with ``UCHII colors'' are found to be associated with arcminute-scale extended sources, rather than with compact or unresolved radio sources, may have important implications on the estimated lifetime of UCHII regions
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