Engineering topics
Publications and source records attributed to Dougherty, D..
Titan's atmosphere produces a wealth of organic products from methane and nitrogen. These products, deposited on the surface in liquid and solid form, may interact with surface ices and energy sources to produce compounds of exobiological interest. Additional information is contained in the original extended abstract.
Saturn's largest moon Titan has a cold, very dense nitrogen atmosphere rich in methane and the hydrocarbon and nitride products of methane photolysis. Sources of energy for atmospheric chemistry include solar ultraviolet radiation, Saturn magnetospheric particles, and galactic cosmic rays. The chemistry of Titan's atmosphere, while interesting from the point of view of planetary photochemistry, is largely free radical driven and therefore not particularly suited to the synthesis of polymeric biomolecules or even their precursors. However, the nature of Titan's atmosphere, in particular its redox state (hydrogen escapes rapidly and is under abundant compared to in the giant planets), and the presence of a variegated surface make consideration of surface chemistry on Titan interesting from an astrobiological viewpoint. Additional information is contained in the original extended abstract.
A multiple-write electron beam lithography techniques is described as linear filter on the grating spatial frequency spectrum.
This work discusses results using the self-heterodyne delay atechnique to measure 1.3 um InP based DFB lasers. We will also address practical issues concerning detection and elimination of back reflections, choice of fiber length and resolution, and measurement of laser 1/f and current supply noise.
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The continued need for increased bandwidth is driving the pursuit of both increased speed in TDM and more channels in WDM for fiber optic communication systems.
Multi-wavelength arrays of colliding pulse mode-locked (CPM) lasers have been demonstrated for wavelength division multiplexing (WDM) applications. The need for increased bandwidth is driving the development of both increased speed in time division multiplexing (TDM) and more channels in WDM for fiber optic communication systems.
The current status of tunable diode lasers (TDLs) for spectroscopy and metrology systems is reviewed.
Through the use of a constrained Newton-Raphson time stepping finite element scheme, the inelastic thermomechanical response of ceramic coated gas turbine parts is considered. Due to the generality of the solution procedure developed, the combined thermoelastic-plastic-creep properties associated with ceramics is treated. This includes the handling of temperature-dependent elastic-plastic creep and thermal material properties. To illustrate the procedure, the thermomechanical response of ceramic coated outer gas path seals is considered. This includes the evaluation of time-dependent thermal ratcheting and its concomitant residual stress and strain fields.
This paper investigates the thermomechanical response of ceramically coated metal parts in elevated thermal environments. This is made possible through the development of an improved finite element algorithm that enables the efficient and stable solution of the inherently nonlinear elastic-creep (inelastic) type thermomechanical field equations associated with high temperature. Based on the improved algorithm, the results of several numerical experiments are presented. These illustrate the significant influence of inelastic behavior in generating residual stress fields.
V/STOL cockpit information advances and cockpit design problems
Dynamic response of rigid bearing, simple rotor system subjected to impact loads applied to rotor or pedestal support