ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Your email was sent successfully. Check your inbox.

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

Proceed reservation?

Export
Filter
  • FLUID MECHANICS AND HEAT TRANSFER  (7)
  • SOLID-STATE PHYSICS  (3)
  • 2020-2022
  • 2005-2009
  • 1990-1994  (10)
  • 1990  (10)
  • 1
    facet.materialart.
    Unknown
    Direct spectroscopy of electron and hole scattering (1990)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: A new spectroscopy has been developed for the first direct probe of carrier-carrier scattering in materials. This spectroscopy provides spatial and energy resolution of the scattering process and has been used to investigate transport, scattering phenomena, and hot-carrier creation in two important metal-semiconductor systems. A theoretical treatment of this scattering spectroscopy yields excellent agreement with experimental spectra and provides direct evidence that carrier-carrier scattering is a dominant energy-loss mechanism in hot-carrier transport.
    Keywords: SOLID-STATE PHYSICS
    Type: Physical Review Letters (ISSN 0031-9007); 64; 2679-268
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 2
    facet.materialart.
    Unknown
    Long-wave morphological instabilities in the directional solidification of a dilute binary mixture (1990)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: Long-wave instabilities in a directionally-solidified binary mixture may occur in several limits. Sivashinsky (1983) identified a small-segregation-coefficient limit and obtained a weakly nonlinear evolution equation governing subcritical two-dimensional bifurcation. Brattkus and Davis (1988) identified a near-absolute-stability limit and obtained a strongly nonlinear evolution equation governing supercritical two-dimensional bifurcation. The present investigation identifies a third strongly nonlinear evolution equation, arising in the small-segregation-coefficient, large-surface-energy limit. This equation links both of the former and describes the change from the sub- to super-critical bifurcations. This study sets the previous long-wave analyses into a logical framework.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: SIAM Journal on Applied Mathematics (ISSN 0036-1399); 50; 420-436
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 3
    facet.materialart.
    Unknown
    Hydrodynamic interactions in directional solidification (1990)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: A binary liquid undergoes unidirectional solidification. The one-dimensional steady state is susceptible to morphological instability that causes the solid/liquid interface to change from a planar state to a cellular pattern. This paper examines the effects on this transition of volume-change convection, buoyancy-driven convection or forced flows. It emphasizes how flows alter stability limits, create scale and pattern changes in morphology, and create, through coupling, new instabilities. Emphasis is placed on the physical mechanisms of the interactions.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Journal of Fluid Mechanics (ISSN 0022-1120); 212; 241-262
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 4
    facet.materialart.
    Unknown
    Long-wave interactions in morphological and convective instabilities (1990)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: A binary liquid that undergoes directional solidification is susceptible to morphological and solutal-convective instabilities that cause the solid/liquid interface to change from a planar to a cellular state. This paper gives derivations for those long-wave evolution equations that describe the weak couplings between convection and interface morphology and gives some analytical results obtainable from these.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: IMA Journal of Applied Mathematics (ISSN 0272-4960); 45; 3, 19; 267-285
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 5
    facet.materialart.
    Unknown
    Experimental investigation of turbulent flow through a circular-to-rectangular transition duct (1990)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: An incompressible, turbulent, swirl-free flow through a circular-to-rectangular transition duct was studied experimentally. The cross-sectional geometry all along the duct was defined using the equation of a superellipse. The three mean velocity components and the six Reynolds stress components were measured at two axial stations downstream from the transition. It is shown that a secondary flow vortex pair which develops along the duct sidewalls significantly distorts the mean and turbulence fields. At the duct exit, the flow is not in local equilibrium, but recovers to local equilibrium conditions in the rectangular extension duct. Analysis demonstrates that conventional wall functions are not applicable at all streamwise locations in the duct.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: AIAA PAPER 90-1505
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 6
    facet.materialart.
    Unknown
    Dependence of millimeter wave surface resistance on the deposition parameters of laser ablated YBa2Cu3O(x) thin films (1990)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: Measurements of millimeter-wave surface resistance versus temperature have been performed for YBa2Cu3O(x) thin films on 100 line-type SrTiO(3) substrates using a TE(011) cylindrical copper cavity at 80 GHz. The 0.6-micron thick films were grown at several deposition temperatures in the range 690 C to 810 C by means of a pulsed excimer laser ablation technique. A surface resistance minimum (60 milliohm at 77 K) near 770 C is shown to correlate with a minimum in c-axis lattice parameter (11.72 A). The highest value of Tc also occurs near this temperature. The surface resistance of films deposited at 790 C on 110 line-type LaAlO3 subtrates is lower, reaching 8 milliohm at 98 GHz and 80 K, demonstrating the influence of substate material on film quality.
    Keywords: SOLID-STATE PHYSICS
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 7
    facet.materialart.
    Unknown
    Unsteady analysis of hot streak migration in a turbine stage (1990)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: Two- and three-dimensional Navier-Stokes analyses are used to predict unsteady viscous rotor-stator interacting flow in the presence of a combustor hot streak. Predicted results are presented for a two-dimensional three-stator/four-rotor, a two-dimensional one-stator/one-rotor, and a three-dimensional one-stator/one-rotor simulation of hot streak migration through a turbine stage. Comparison of these results with experimental data demonstrates the capability of the three-dimensional procedure to capture most of the flow physics associated with hot streak migration including the effects of combustor hot streaks on turbine rotor surface temperatures. It is noted that blade count ratio has little effect on predicted time-averaged surface pressure and temperature distributions, but a substantial effect on the unsteady flow characteristics. It is shown that high-temperature hot streak fluid accumulates on the pressure surface of the rotor blades, resulting in a high time-averaged surface temperature 'hot spots'.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: AIAA PAPER 90-2354
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 8
    facet.materialart.
    Unknown
    Silicon carbide semiconductor device fabrication and characterization (1990)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: A number of basic building blocks i.e., rectifying and ohmic contacts, implanted junctions, MOS capacitors, pnpn diodes and devices, such as, MESFETs on both alpha and beta SiC films were fabricated and characterized. Gold forms a rectifying contact on beta SiC. Since Au contacts degrade at high temperatures, these are not considered to be suitable for high temperature device applications. However, it was possible to utilize Au contact diodes for electrically characterizing SiC films. Preliminary work indicates that sputtered Pt or Pt/Si contacts on beta SiC films are someways superior to Au contacts. Sputtered Pt layers on alpha SiC films form excellent rectifying contacts, whereas Ni layers following anneal at approximately 1050 C provide an ohmic contact. It has demonstrated that ion implantation of Al in substrates held at 550 C can be successfully employed for the fabrication of rectifying junction diodes. Feasibility of fabricating pnpn diodes and platinum gated MESFETs on alpha SiC films was also demonstrated.
    Keywords: SOLID-STATE PHYSICS
    Type: NASA-CR-186354 , NAS 1.26:186354 , AD-A231299
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 9
    facet.materialart.
    Unknown
    On the buoyancy-driven motion of a drop towards a rigid surface or a deformable interface (1990)
    In:  Other Sources
    Details
    Publication Date: 2019-07-12
    Description: The deformation of a viscous drop, driven by buoyancy toward a solid surface or a deformable interface, is analyzed in the asymptotic limit of small Bond number, for which the deformation becomes important only when the drop is close to the solid surface or interface. Lubrication theory is used to describe the flow in the thin gap between the drop and the solid surface or interface, and boundary-integral theory is used in the fluid phases on either side of the gap. The evolution of the drop shape is traced from a relatively undeformed state until a dimple is formed and a long-time quasi-steady-state pattern is established. A wide range of drop to suspending phase viscosity ratios is examined. It is shown that a dimple is always formed, independently of the viscosity ratio, and that the long-time thinning rates take simple forms as inverse fractional powers of time.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Journal of Fluid Mechanics (ISSN 0022-1120); 217; 547-573
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 10
    facet.materialart.
    Unknown
    Experimental investigation of a single flush-mounted hypermixing nozzle (1990)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The results of an experimental wind tunnel investigation of a circular supersonic jet (m sub j = 3.47) injected at a 10 degree angle into a supersonic freestream. The jet penetrates a boundary layer, which has a thickness approximately the same as the jet nozzle exit diameter. Measurements were made for nominal freestream Mach numbers of 1.6, 2.0, 2.5, and 3.0. Three jet total pressures were run at each freestream Mach number, resulting in twelve separate operating conditions. Mean data accumulated by means of static and total pressure probe instrumentation are presented at two axial stations: seven jet nozzle diameters upstream and 15 jet nozzle diameters downstream from where the centerline of the nozzle intersects the wind tunnel wall. For one condition at each freestream Mach number, the jet air was seeded with a hydrocarbon trace gas and the flow was sampled at the downstream measurement plane to quantify the mean mixing of the two streams. Surface oil flow visualization was also used to investigate the flow interaction. All results are for air-to-air mixing. The measurements indicate the presence of two pairs contra-rotating vortices. One pair follows the jet trajectory and tends to split the jet into two streams. A smaller pair, rotating in an opposite sense, develops in the near wall region. Reported results include Mach number and volume fraction distributions in the cross plane, as well as jet penetration and mixing efficiency.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-TM-103726 , E-5960 , NAS 1.15:103726 , AIAA PAPER 90-5240 , Second International Aerospace Planes Conference; Oct 29, 1990 - Oct 31, 1990; Orlando, FL; United States
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...