ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Publication Date: 2011-08-19
    Description: A singular perturbation analysis valid for small grain-boundary slopes is used with the one-sided model for solidification to show that grain boundaries introduce imperfections into the symmetry of the developing cellular interfaces which rupture the junction between the family of planar shapes and the bifurcating cellular families. Undulating interfaces are shown to develop first near grain boundaries, and to evolve with decreasing temperature gradient either by a smooth transition from the almost planar family or by a sudden jump to moderate-amplitude cellular forms, depending on the growth rate.
    Keywords: SOLID-STATE PHYSICS
    Type: Physical Review B, 3rd Series (ISSN 0163-1829); 30; 3993-399
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 2
    Publication Date: 2019-07-13
    Description: Herein we report on a preliminary study to assess the use of the Hubble Space Telescope (HST) for the direct detection and spectroscopic characterization of exoplanets and debris disks - an application for which HST was not originally designed. Coronagraphic advances may enable the design of a science instrument that could achieve limiting contrasts approx.10deg beyond 275 milli-arcseconds (4 lambda/D at 800 nm) inner working angle, thereby enabling detection and characterization of several known jovian planets and imaging of debris disks. Advantages of using HST are that it already exists in orbit, it's primary mirror is thermally stable and it is the most characterized space telescope yet flown. However there is drift of the HST telescope, likely due to thermal effects crossing the terminator. The drift, however, is well characterized and consists of a larger deterministic components and a smaller stochastic component. It is the effect of this drift versus the sensing and control bandwidth of the instrument that would likely limit HST coronagraphic performance. Herein we discuss the science case, quantifY the limiting factors and assess the feasibility of using HST for exoplanet discovery using a hypothetical new instrument. Keywords: Hubble Space Telescope, coronagraphy, exoplanets, telescopes
    Keywords: Astronomy
    Type: GSFC.CPR.4894.2011 , SPIE 7731, Astronomical Telescopes and Instrumentation, San Diego CA, June 2010; Jun 01, 2010; San Diego, CA; United States
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 3
    Publication Date: 2019-07-18
    Description: The planned testing of the Advanced Mirror System Demonstrator program being performed by Ball Aerospace are presented.
    Keywords: Instrumentation and Photography
    Type: 2nd Annual Technology Days; May 22, 2002 - May 24, 2002; Huntsville, AL; United States
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 4
    Publication Date: 2019-07-18
    Description: The Sub-scale Beryllium Mirror Demonstrator that was successfully tested to demonstrate cryogenic figuring of a bare mirror has been coated with a protected gold reflective surface and retested at cryogenic temperatures. Results showing less than 9 nm rms surface distortion attributable to the added coating are presented.
    Keywords: Instrumentation and Photography
    Type: 2nd Annual Technology Days; May 22, 2002 - May 24, 2002; Huntsville, AL; United States
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 5
    Publication Date: 2019-07-18
    Description: The current status of the Advanced Mirror System Demonstrator program being performed by Ball Aerospace is presented. The hexagonal low-areal density Beryllium mirror blank has been fabricated and undergoing polishing at the time of this presentation.
    Keywords: Instrumentation and Photography
    Type: 2nd Annual Technology Days; May 22, 2002 - May 24, 2002; Huntsville, AL; United States
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 6
    Publication Date: 2019-07-19
    Description: Recent near-infrared spectroscopy of Kuiper Belt objects and Centaurs indicates considerable spectral diversity among them. Some have entirely bland spectra with no discernible spectral features (e.g., Chiron), while 5145 Pholus has a very active spectrum with absorption bands of H2O, CH3OH, and probably the mineral olivine present. In addition, the strong red color of Pholus indicates the presence of organic solids. Among the KBOs, 1993 SC has an active spectrum with the probably presence of hydrocarbons and possibly the ices of H2O and N2. The diversity among these spectra and the implications that such diversity has for models of the formation of the formation of the planets will be discussed.
    Keywords: Astronomy
    Type: Protostars and Planets IV Conference; Jul 06, 1998 - Jul 10, 1998; Santa Barbara, CA; United States
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 7
    Publication Date: 2019-08-28
    Description: The wide range of length and time scales involved in industrial scale solidification processes is demonstrated here by considering the Czochralski process for the growth of large diameter silicon crystals that become the substrate material for modern microelectronic devices. The scales range in time from microseconds to thousands of seconds and in space from microns to meters. The physics and chemistry needed to model processes on these different length scales are reviewed.
    Keywords: SOLID-STATE PHYSICS
    Type: In: Heat and mass transfer in materials processing (A93-10826 01-31); p. 137-153.
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 8
    facet.materialart.
    Unknown
    In:  Other Sources
    Publication Date: 2019-07-13
    Description: Overall program completeness is optimized by selecting the ordered set of observations and targets that maximizes the efficiency for the ensemble of stars. We describe the optimization approach and report on completeness sensitivity to instrument throughput, inner working angle, instrument sensitivity, observational overhead, exo-zodiacal brightness, and target revisit constraints.
    Keywords: Instrumentation and Photography
    Type: Terrestrial Planet Finder - Coronagraph STDT #5; Nov 30, 2005; Pasadena, CA; United States
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 9
    Publication Date: 2019-07-13
    Description: The Terrestrial Planet Finder Coronagraph (TPF-C) is a NASA pre-phase. A orbiting telescope with the goal of detecting and characterizing visible and near-IR light refelected from terrestrial planets. We use observational completeness, defined as the fraction of potentially observable planets that are detected, to determine how well the proposed telescope meets the mission goals. Single visit completeness is optimized by slecting the length of observation per target that maximizes the completeness for the ensemble of stars. In this memo we describe the integration time calculations and two approaches to single visit optimization.
    Keywords: Instrumentation and Photography
    Type: Terrestrial Planet Finder - Coronagraph STDT #5; Nov 30, 2005; Pasadena, CA; United States
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 10
    Publication Date: 2019-07-12
    Description: Meniscus-defined techniques for the growth of thin silicon sheets fall into two categories: vertical and horizontal growth. The interactions of the temperature field and the crystal shape are analyzed for both methods using two-dimensional finite-element models which include heat transfer and capillarity. Heat transfer in vertical growth systems is dominated by conduction in the melt and the crystal, with almost flat melt/crystal interfaces that are perpendicular to the direction of growth. The high axial temperature gradients characteristic of vertical growth lead to high thermal stresses. The maximum growth rate is also limited by capillarity which can restrict the conduction of heat from the melt into the crystal. In horizontal growth the melt/crystal interface stretches across the surface of the melt pool many times the crystal thickness, and low growth rates are achievable with careful temperature control. With a moderate axial temperature gradient in the sheet a substantial portion of the latent heat conducts along the sheet and the surface of the melt pool becomes supercooled, leading to dendritic growth. The thermal supercooling is surpressed by lowering the axial gradient in the crystal; this configuration is the most desirable for the growth of high quality crystals. An expression derived from scaling analysis relating the growth rate and the crucible temperature is shown to be reliable for horizontal growth.
    Keywords: SOLID-STATE PHYSICS
    Type: Journal of Crystal Growth (ISSN 0022-0248); 82; 1-2; 1-9
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...