10,452 research outputs found

    Aditional Ultra-High-Resolution Observations of Ca+ Ions in the Local Insterstellar Medium

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    We present ultra-high-resolution (0.35 km sāˆ’1 FWHM) observations of the interstellar Ca K line towards seven nearby stars. The spectral resolution was sufficient to resolve the line profiles fully, thereby enabling us to detect hitherto unresolved velocity components, and to obtain accurate measurements of the velocity dispersions (b values). Absorption components with velocities similar to those expected for the Local Interstellar Cloud (LIC) and the closely associated ā€˜G cloudā€™ were identified towards six of the seven stars. However, in most cases the b values deduced for these components were significantly larger than the b ā‰ˆ 2.2 km sāˆ’1 (i.e. Tk ā‰ˆ 7000 K, vt ā‰ˆ 1 km sāˆ’1) expected for the LIC, and it is argued that this results from the presence of additional, spectrally unresolved, components having similar velocities and physical conditions. For two stars (Ī“ Vel and Ī± Pav) we detect interstellar components with much smaller b values (1.1 Ā± 0.3 and 0.8 Ā± 0.1 km sāˆ’1, respectively) than are expected for low-density clouds within the Local Bubble. In the case of the narrow Ī± Pav component, we also find an anomalously large Na i/Ca ii column density ratio, which is indicative of a relatively high density. Thus it is possible that, in addition to LIC-type clouds, the local interstellar medium contains a population of previously undetected cooler and denser interstellar clouds

    Solar energy conversion through the interaction of plasmons with tunnel junctions. Part A: Solar cell analysis. Part B: Photoconductor analysis

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    A solar cell utilizing guided optical waves and tunnel junctions was analyzed to determine its feasibility. From this analysis, it appears that the limits imposed upon conventional multiple cell systems also limit this solar cell. Due to this limitation, it appears that the relative simplicity of the conventional multiple cell systems over the solar cell make the conventional multiple cell systems the more promising candidate for improvement. It was discovered that some superlattice structures studied could be incorporated into an infrared photodetector. This photoconductor appears to be promising as a high speed, sensitive (high D sup star sub BLIP) detector in the wavelength range from 15 to over 100 micrometers

    Space shuttle engineering and operations support. Avionics system engineering

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    The shuttle avionics integration laboratory (SAIL) requirements for supporting the Spacelab/orbiter avionics verification process are defined. The principal topics are a Spacelab avionics hardware assessment, test operations center/electronic systems test laboratory (TOC/ESL) data processing requirements definition, SAIL (Building 16) payload accommodations study, and projected funding and test scheduling. Because of the complex nature of the Spacelab/orbiter computer systems, the PCM data link, and the high rate digital data system hardware/software relationships, early avionics interface verification is required. The SAIL is a prime candidate test location to accomplish this early avionics verification

    Gas Absorption Detected from the Edge-on Debris Disk Surrounding HD32297

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    Near-infrared and optical imaging of HD32297 indicate that it has an edge-on debris disk, similar to beta Pic. I present high resolution optical spectra of the NaI doublet toward HD32297 and stars in close angular proximity. A circumstellar absorption component is clearly observed toward HD32297 at the stellar radial velocity, which is not observed toward any of its neighbors, including the nearest only 0.9 arcmin away. An interstellar component is detected in all stars >90 pc, including HD32297, likely due to the interstellar material at the boundary of the Local Bubble. Radial velocity measurements of the nearest neighbors, BD+07 777s and BD+07 778, indicate that they are unlikely to be physically associated with HD32297. The measured circumstellar column density around HD32997, log N(NaI) ~ 11.4, is the strongest NaI absorption measured toward any nearby main sequence debris disk, even the prototypical edge-on debris disk, beta Pic. Assuming that the morphology and abundances of the gas component around HD32297 are similar to beta Pic, I estimate an upper limit to the gas mass in the circumstellar disk surrounding HD32297 of ~0.3 M_Earth.Comment: 13 pages, 2 figures; Accepted for publication in ApJ Letter

    Property Insurance for Ohio\u27s Urban Areas

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    Thirty-eight million dollars damage to property occurred in Watts in 1965, 49,000,000inDetroit,and49,000,000 in Detroit, and 10,000,000 in Newark, New Jersey in 1967, plus many others that have resulted in about $187,000,000 being paid in the five years ending in 1968. Until Watts, riot coverage was provided as an afterthought by the insurance industry with little or no additional charge. Besides this problem, insurers were faced with loss of reinsurance by foreign reinsurers alarmed by inability of Government authorities to maintain law and order

    Property Insurance for Ohio\u27s Urban Areas

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    Thirty-eight million dollars damage to property occurred in Watts in 1965, 49,000,000inDetroit,and49,000,000 in Detroit, and 10,000,000 in Newark, New Jersey in 1967, plus many others that have resulted in about $187,000,000 being paid in the five years ending in 1968. Until Watts, riot coverage was provided as an afterthought by the insurance industry with little or no additional charge. Besides this problem, insurers were faced with loss of reinsurance by foreign reinsurers alarmed by inability of Government authorities to maintain law and order

    Reweighted nuclear norm regularization: A SPARSEVA approach

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    The aim of this paper is to develop a method to estimate high order FIR and ARX models using least squares with re-weighted nuclear norm regularization. Typically, the choice of the tuning parameter in the reweighting scheme is computationally expensive, hence we propose the use of the SPARSEVA (SPARSe Estimation based on a VAlidation criterion) framework to overcome this problem. Furthermore, we suggest the use of the prediction error criterion (PEC) to select the tuning parameter in the SPARSEVA algorithm. Numerical examples demonstrate the veracity of this method which has close ties with the traditional technique of cross validation, but using much less computations.Comment: This paper is accepted and will be published in The Proceedings of the 17th IFAC Symposium on System Identification (SYSID 2015), Beijing, China, 201
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