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  • Optics  (4)
  • Astronomy; Instrumentation and Photography; Optics  (1)
  • Attributed adjacency graph  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    The international journal of advanced manufacturing technology 13 (1997), S. 713-722 
    ISSN: 1433-3015
    Keywords: Attributed adjacency graph ; Convex hull ; Feature interaction ; Feature recognition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Handling feature interaction is an outstanding issue in the feature recognition approach. This paper presents a method for recognising the presence of feature interactions and for determining the feature components within the interactions. First, two general feature types, namely depression and protrusion features, are identified from B-rep models based on a modified convex hull concept. Secondly, the identified features are represented by a modified AAG (Attributes Adjacency Graph) for facilitating their classification into low-level feature components, such as slots, pockets and bosses. Any unrecognisable features that remain after this second step are regarded as interacting features and they are finally recognised as low-level features via a process of virtual face building and volume adding.
    Type of Medium: Electronic Resource
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  • 2
    Publication Date: 2018-06-06
    Description: Determination of the shape of very thin x-ray mirrors employed in spaced-based telescopes continues to be challenging. The mirrors shapes are not readily deduced to the required accuracy because the mount induced distortions are often larger than the uncertainty tolerable for the mission metrology. In addition to static deformations, dynamic and thermal considerations are exacerbated for this class of mirrors. We report on the performance of one temporary mounting scheme for the thin glass mirrors for the Constellation-X mission and prospects for deducing their undistorted shapes.
    Keywords: Optics
    Format: application/pdf
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  • 3
    Publication Date: 2019-07-13
    Description: X-ray optics with both high angular resolution and lightweight is essential for further progress in x-ray astronomy. High angular resolution is important in avoiding source confusion and reducing background to enable the observation of the most distant objects of the early Universe. It is also important in enabling the use of gratings to achieve high spectral resolution to study, among other things, the myriad plasmas that exist in planetary, stellar, galactic environments, as well as interplanetary, inter-stellar, and inter-galactic media. Lightweight is important for further increase in effective photon collection area, because x-ray observations must take place on space platforms and the amount of mass that can be launched into space has always been very limited and is expected to continue to be very limited. This paper describes an x-ray optics development program and reports on its status that meets these two requirements. The objective of this program is to enable Explorer type missions in the near term and to enable flagship missions in the long term.
    Keywords: Optics
    Type: GSFC.CP.5268.2011 , SPIE meeting; Aug 21, 2011 - Aug 25, 2011; San Diego, CA; United States
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  • 4
    Publication Date: 2019-07-13
    Description: X-ray astronomy depends on the availability of telescopes with high resolution and large photon collecting areas. Since x-ray observation can only be carried out above the atmosphere, these telescopes must be necessarily lightweight. Compounding the lightweight requirement is that an x-ray telescope consists of many nested concentric shells, which further require that x-ray mirrors must also be geometrically thin to achieve high packing efficiency. This double lightweight and geometrically thin requirement poses significant technical challenges in fabricating the mirrors and in integrating them into mirror assemblies. This paper reports on the approach, strategy and status of our x-ray optics development program whose objective is to meet these technical challenges at modest cost to enable future x-ray missions, including small Explorer missions in the near term, probe class missions in the medium term, and large flagship missions in the long term.
    Keywords: Optics
    Type: GSFC.JA.7104.2012 , SPIE Proceedings; 8843
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  • 5
    Publication Date: 2019-07-13
    Description: Future x-ray astronomical missions require x-ray mirror assemblies that provide both high angular resolution and large photon collecting area. In addition, as x-ray astronomy undertakes more sensitive sky surveys, a large field of view is becoming increasingly important as well. Since implementation of these requirements must be carried out in broad political and economical contexts, any technology that meets these performance requirements must also be financially affordable and can be implemented on a reasonable schedule. In this paper we report on progress of an x-ray optics development program that has been designed to address all of these requirements. The program adopts the segmented optical design, thereby is capable of making both small and large mirror assemblies for missions of any size. This program has five technical elements: (1) fabrication of mirror substrates, (2) coating, (3) alignment, (4) bonding, and (5) mirror module systems engineering and testing. In the past year we have made progress in each of these five areas, advancing the angular resolution of mirror modules from 10.8 arc-seconds half-power diameter reported (HPD) a year ago to 8.3 arc-seconds now. These mirror modules have been subjected to and passed all environmental tests, including vibration, acoustic, and thermal vacuum. As such this technology is ready for implementing a mission that requires a 10-arc-second mirror assembly. Further development in the next two years would make it ready for a mission requiring a 5-arc-second mirror assembly. We expect that, by the end of this decade, this technology would enable the x-ray astrophysical community to compete effectively for a major x-ray mission in the 2020s that would require one or more 1-arc-second mirror assemblies for imaging, spectroscopic, timing, and survey studies.
    Keywords: Astronomy; Instrumentation and Photography; Optics
    Type: GSFC-E-DAA-TN31207 , Proceedings of SPIE; 9144
    Format: text
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  • 6
    Publication Date: 2019-07-13
    Description: We present an overview update of the metrological approach to be employed for the segmented mirror fabrication for Constellation-X spectroscopy x-ray telescope. We compare results achieved to date with mission requirements. This is discussed in terms of inherent capability versus in-practice capability.
    Keywords: Optics
    Type: SPIE Conference: Optics and Photonics 2007; Aug 26, 2007 - Aug 30, 2007; San Diego, CA; United States
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