Exact Solutions for Sound Radiation from a Circular Duct

This paper presents a method of evaluation of Wiener-Hopf technique solutions for sound radiation from an unflanged circular duct with infinitely thin duct wall, including mean flows

PERUBAHAN RETENSI AIR PADA ZONE PERAKARAN TANAMAN JAGUNG AKIBAT APLIKASI BAHAN ORGANIK ECENG GONDOK (EICHORNIA CRASSIPES)

Management system implemented aimed to preventing land degradation and improve water availability in the rooting zone of Zea mays plantation. Increased availability of high water as inplikasi ability of organic matter in binding water. The research method using field experiments with Completely Random Design with five levels, ie, P0 = without Eichornia crassipess organic matter or control, P1 = 3 ton.ha-1 E. crassipess organic matter, P2 = 6 ton.ha-1 E. crassipess organic matter, P3 = 9 ton.ha-1 E. crassipess organic matter, and P4 = 12 ton.ha-1 E. crassipess organic matter. The results obtained showed that the treatment of E. crassipess organic matter 12 ton ha-1 can increase water retention at pF pF 1.00 and 2.00 times respectively at 1.19 and 1.17 times larger compared with the untreated organic matter (P0). Key words: E. crassipess, water retention, Zea may

Effects of carbon incorporation on doping state of YBa2Cu3Oy

Effects of carbon incorporation on the doping state of YBa2Cu3Oy (Y-123) were investigated. Quantitative carbon analysis revealed that carbon could be introduced into Y-123 from both the precursor and the sintering gas. Nearly carbon-free (< 200 ppm) samples were prepared from a vacuum-treated precursor by sintered at 900 &#730;C and cooling with 20 &#730;C /min in flowing oxygen gas. The lower Tc (= 88 K) and higher oxygen content (y = 6.98) strongly suggested the overdoping state, which was supported by the temperature dependence of resisitivity and thermoelectric power. The nuclear quadrapole resonance spectra and the Raman scattering spectra indicated that there was almost no oxygen defect in the Cu-O chain in these samples. On the other hand, in the same cooling condition, the samples sintered in air stayed at optimal doping level with Tc = 93 K, and the intentionally carbon-doped sample was in the underdoping state. It is revealed that about 60% of incorporated carbon was substituted for Cu at the chain site in the form of CO32+, and the rest remains at the grain boundary as carbonate impurities. Such incorporation affected the oxygen absorption process in Y-123. It turned out that the oxygen content in Y-123 cannot be controlled only by the annealing temperature and the oxygen partial pressure but also by the incorporated carbon concentration.Comment: 16pages, 9figure

Performance of a Low Noise Front-end ASIC for Si/CdTe Detectors in Compton Gamma-ray Telescope

Compton telescopes based on semiconductor technologies are being developed to explore the gamma-ray universe in an energy band 0.1--20 MeV, which is not well covered by the present or near-future gamma-ray telescopes. The key feature of such Compton telescopes is the high energy resolution that is crucial for high angular resolution and high background rejection capability. The energy resolution around 1 keV is required to approach physical limit of the angular resolution due to Doppler broadening. We have developed a low noise front-end ASIC (Application-Specific Integrated Circuit), VA32TA, to realize this goal for the readout of Double-sided Silicon Strip Detector (DSSD) and Cadmium Telluride (CdTe) pixel detector which are essential elements of the semiconductor Compton telescope. We report on the design and test results of the VA32TA. We have reached an energy resolution of 1.3 keV (FWHM) for 60 keV and 122 keV at 0 degree C with a DSSD and 1.7 keV (FWHM) with a CdTe detector.Comment: 6 pages, 7 figures, IEEE style file, to appear in IEEE Trans. Nucl. Sc