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  • Optics  (4)
  • Engineering (General)  (3)
  • Feature recognition  (1)
  • 1
    Digitale Medien
    Digitale Medien
    A method for recognising feature interactions and feature components within the interactions (1997)
    Springer
    The international journal of advanced manufacturing technology 13 (1997), S. 713-722 
    Details
    ISSN: 1433-3015
    Schlagwort(e): Attributed adjacency graph ; Convex hull ; Feature interaction ; Feature recognition
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Notizen: 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.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01179071
    Standort Signatur Erwartet Verfügbarkeit
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    Artikel (Nationallizenzen)
    Volltext
  • 2
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    Some Considerations for Precision Metrology of Thin X-Ray Mirrors (2008)
    In:  CASI
    Details
    Publikationsdatum: 2018-06-06
    Beschreibung: 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.
    Schlagwort(e): Optics
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
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    NASA TECHNICAL REPORTS
  • 3
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    Unbekannt
    Superpolishing and Precision Metrology on a Metal Mandrel and Replicated Segments for Constellation-X (1999)
    In:  Other Sources
    Details
    Publikationsdatum: 2019-07-13
    Beschreibung: We have superpolished a diamond-turned aluminum mandrel (coated with electroless Ni) to an axial roughness of 0.34 nm rms. The mandrel is made to the Astro-E secondary mirror design for the 81st shell. Precision metrology at 100 mm to submicron scales has established the power spectral density of the mandrel and ultralightweight gold coated replicated segments. Predicted image quality of a set of optimally aligned replicated segments of this and a matching primary is substantially improved as compared to the flight mirrors for Astro-E. This approach using metal mandrels, superpolishing, and replicated ultralightweight foil mirrors, may represent a cost-effective approach to meeting the 15 arcsec half-energy width and weight requirements for the Constellation-X mission. Descriptions of the polishing apparatus, the precision metrology instruments, and the surface data analysis are presented. The general methods described are applicable to precision optics for both normal incidence and grazing incidence optics.
    Schlagwort(e): Engineering (General)
    Materialart: Jul 01, 1999; Unknown
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
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    NASA TECHNICAL REPORTS
  • 4
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    High Angular Resolution and Lightweight X-Ray Optics for Astronomical Missions (2011)
    In:  CASI
    Details
    Publikationsdatum: 2019-07-13
    Beschreibung: 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.
    Schlagwort(e): Optics
    Materialart: GSFC.CP.5268.2011 , SPIE meeting; Aug 21, 2011 - Aug 25, 2011; San Diego, CA; United States
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
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    NASA TECHNICAL REPORTS
  • 5
    facet.materialart.
    Unbekannt
    Next Generation Astronomical X-ray Optics: High Angular Resolution, Light Weight, and Low Production Cost (2012)
    In:  CASI
    Details
    Publikationsdatum: 2019-07-13
    Beschreibung: 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.
    Schlagwort(e): Optics
    Materialart: GSFC.JA.7104.2012 , SPIE Proceedings; 8843
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
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    NASA TECHNICAL REPORTS
  • 6
    facet.materialart.
    Unbekannt
    Superpolishing and Precision Metrology on a Metal Mandrel and Replicated Segments for Constellation-X (1999)
    In:  Other Sources
    Details
    Publikationsdatum: 2019-07-17
    Beschreibung: We have superpolished a diamond-turned aluminum mandrel (coated with electroless Ni) to an axial roughness of 0.34 nm rms. The mandrel is made to the Astro-E secondary mirror design for the 81st shell. Precision metrology at 100 mm to submicron scales has established the power spectral density of the mandrel and ultralightweight gold coated replicated segments. Predicted image quality of a set of optimally aligned replicated segments of this and a matching primary is substantially improved as compared to the flight mirrors for Astro-E. This approach using metal mandrels, superpolishing, and replicated ultralightweight foil mirrors, may represent a cost-effective approach to meeting the 15 arcsec half-energy width and weight requirements for the Constellation-X mission. Descriptions of the polishing apparatus, the precision metrology instruments, and the surface data analysis are presented. The general methods described are applicable to precision optics for both normal incidence and grazing incidence optics.
    Schlagwort(e): Engineering (General)
    Materialart: SPIE Conference; Jul 01, 1999; United States
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    NASA TECHNICAL REPORTS
  • 7
    facet.materialart.
    Unbekannt
    Superpolishing and Precision Metrology on a Metal Mandrel and Replicated Segments for Constellation-X (1999)
    In:  Other Sources
    Details
    Publikationsdatum: 2019-07-13
    Beschreibung: We have superpolished a diamond-turned aluminum mandrel (coated with electroless Ni) to an axial roughness of 6.34 nm rms. The mandrel is made to the Astro-E secondary mirror design for the 81st shell. Precision metrology at 100 mm to submicron scales has established the power spectral density of the mandrel and ultralightweight gold coated replicated segments. Predicted image quality of a set of optimally aligned replicated segments of this and a matching primary is substantially improved as compared to the flight mirrors for Astro-E. This approach using metal mandrels, superpolishing, and replicated ultralightweight foil mirrors, may represent a cost-effective approach to meeting the 15 arcsec half-energy width and weight requirements for the Constellation-X mission. Descriptions of the polishing apparatus, the precision metrology instruments, and the surface data analysis are presented. The general methods described are applicable to precision optics for both normal incidence and grazing incidence optics.
    Schlagwort(e): Engineering (General)
    Materialart: Jul 01, 1999; Unknown
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
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    NASA TECHNICAL REPORTS
  • 8
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    Unbekannt
    Toward a Complete Metrological Solution for the Mirrors for the Constellation-X Spectroscopy X-ray Telescope (2007)
    In:  CASI
    Details
    Publikationsdatum: 2019-07-13
    Beschreibung: 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.
    Schlagwort(e): Optics
    Materialart: SPIE Conference: Optics and Photonics 2007; Aug 26, 2007 - Aug 30, 2007; San Diego, CA; United States
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
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