Front Rendering on the GPU

The glyphs described in a font are usually rendered using software that runs on the CPU. This can be done very quickly and is a well understood process. These techniques work well when the glyph is rendered such that each point on the rendered glyph maps one-to-one to pixels on the screen. When this one-to-one mapping is removed, visual quality can degrade dramatically. This thesis describes a method to avoid this degradation by moving the rendering of glyphs from the CPU to the Graphics Processing Unit (GPU). This method extracts glyph metrics from Truetype font files using the FreeType library, processes all glyph data in the font file and places it into a form that can be used by GPU shader programs to draw the glyphs such that the visual quality does not degrade regardless of the applied transformations

Effects of Food-Grade Nonionic Surfactants on the Iron-Catalyzed Oxidative Stability of Lycopene in Oil-in-Water Emulsions

In this research a novel method for the rapid, direct measurement of oxidative lycopene degradation in oil-in-water emulsions via colorimetric means was developed. This analytical method was used to conduct experiments monitoring the degradation of lycopene-containing oil-in-water emulsions of decane spontaneously formed in the presence of nonionic surfactants (Span and Tween) of different tail lengths and molar ratios. The structure and ratio of these nonionic surfactants was manipulated to probe the mechanism of lycopene stabilization when iron-catalyzed oxidation was the main pathway of degradation, as controlled by pH and oil phase selection. The effect of addition of chloride salts with different cations was also investigated. Optimum conditions for evaluation were developed using a Span 80/Tween 80 surfactant combination and lycopene extracted into decane from tomato paste. Using 0.5% FeCl3 concentration and ~2 millimoles surfactant at a pH of ~3, 2-hour degradation experiments were performed to evaluate various Span/Tween nonionic surfactant combinations for oxidative stability. Tails of lauryl (C12), myristyl (C14), stearyl (C18) and oleyl (C18:1 unsaturated) groups were evaluated. It was found that in general, for a fixed molar amount of surfactant, increasing the amount of Tween (hydrophilic surfactant) increased the stability of the lycopene emulsion. In addition, tail length of the surfactant plays a role in the stability of the emulsions with shorter, less hydrophobic tail lengths providing better oxidative stability. Lithium, sodium, and potassium chloride were added to emulsions of lycopene in decane made with Span 20 and Tween 20 surfactants and evaluated for oxidative stability in iron-catalyzed conditions. It was found that stability decreased according to the Hofmeister Series for cations. The order of stability was found to be: K+ \u3e Na+ \u3e Li+. Increasing concentration of cation resulted in decreased lycopene stability for all cations

Calculated performance, stability and maneuverability of high-speed tilting-prop-rotor aircraft

The feasibility of operating tilting-prop-rotor aircraft at high speeds is examined by calculating the performance, stability, and maneuverability of representative configurations. The rotor performance is examined in high-speed cruise and in hover. The whirl-flutter stability of the coupled-wing and rotor motion is calculated in the cruise mode. Maneuverability is examined in terms of the rotor-thrust limit during turns in helicopter configuration. Rotor airfoils, rotor-hub configuration, wing airfoil, and airframe structural weights representing demonstrated advance technology are discussed. Key rotor and airframe parameters are optimized for high-speed performance and stability. The basic aircraft-design parameters are optimized for minimum gross weight. To provide a focus for the calculations, two high-speed tilt-rotor aircraft are considered: a 46-passenger, civil transport and an air-combat/escort fighter, both with design speeds of about 400 knots. It is concluded that such high-speed tilt-rotor aircraft are quite practical

Wave combustors for trans-atmospheric vehicles

The Wave Combustor is an airbreathing hypersonic propulsion system which utilizes shock and detonation waves to enhance fuel-air mixing and combustion in supersonic flow. In this concept, an oblique shock wave in the combustor can act as a flameholder by increasing the pressure and temperature of the air-fuel mixture and thereby decreasing the ignition delay. If the oblique shock is sufficiently strong, then the combustion front and the shock wave can couple into a detonation wave. In this case, combustion occurs almost instantaneously in a thin zone behind the wave front. The result is a shorter, lighter engine compared to the scramjet. This engine, which is called the Oblique Detonation Wave Engine (ODWE), can then be utilized to provide a smaller, lighter vehicle or to provide a higher payload capability for a given vehicle weight. An analysis of the performance of a conceptual trans-atmospheric vehicle powered by an ODWE is given here

Paleointensity estimates from ignimbrites: An evaluation of the Bishop Tuff

Ash flow tuffs, or ignimbrites, typically contain fine-grained magnetite, spanning the superparamagnetic to single-domain size range that should be suitable for estimating geomagnetic field intensity. However, ignimbrites may have a remanence of thermal and chemical origin as a result of the complex magnetic mineralogy and variations in the thermal and alteration history. We examined three stratigraphic sections through the ~0.76 Ma Bishop Tuff, where independent information on postemplacement cooling and alteration is available, as a test of the suitability of ignimbrites for paleointensity studies. Thermomagnetic curves suggest that low-Ti titanomagnetite (Tc = 560°C–580°C) is the dominant phase, with a minor contribution from a higher Tc phase(s). Significant remanence unblocking above 580°C suggests that maghemite and/or (titano)maghemite is an important contributor to the remanence in most samples. We obtained successful paleofield estimates from remanence unblocked between 440°C and 580°C for 46 of 89 specimens (15 sites at two of three total localities). These specimens represent a range of degrees of welding and have variable alteration histories and yet provide a consistent paleofield estimate of 43.0 µT (±3.2), equivalent to a VADM of 7.8 × 1022 Am2. The most densely welded sections of the tuff have emplacement temperatures inferred to be as high as ~660°C, suggesting that the remanence may be primarily thermal in origin, though a contribution from thermochemical remanence cannot be excluded. These results suggest that ignimbrites may constitute a viable material for reliable paleointensity determinations

Skylon Aerodynamics and SABRE Plumes

An independent partial assessment is provided of the technical viability of the Skylon aerospace plane concept, developed by Reaction Engines Limited (REL). The objectives are to verify REL's engineering estimates of airframe aerodynamics during powered flight and to assess the impact of Synergetic Air-Breathing Rocket Engine (SABRE) plumes on the aft fuselage. Pressure lift and drag coefficients derived from simulations conducted with Euler equations for unpowered flight compare very well with those REL computed with engineering methods. The REL coefficients for powered flight are increasingly less acceptable as the freestream Mach number is increased beyond 8.5, because the engineering estimates did not account for the increasing favorable (in terms of drag and lift coefficients) effect of underexpanded rocket engine plumes on the aft fuselage. At Mach numbers greater than 8.5, the thermal environment around the aft fuselage is a known unknowna potential design and/or performance risk issue. The adverse effects of shock waves on the aft fuselage and plumeinduced flow separation are other potential risks. The development of an operational reusable launcher from the Skylon concept necessitates the judicious use of a combination of engineering methods, advanced methods based on required physics or analytical fidelity, test data, and independent assessments

Paleointensity Estimates From Ignimbrites: The Bishop Tuff Revisited

Volcanic ash flow tuffs (ignimbrites) may contain single domain‐sized (titano) magnetite that should be good for recording geomagnetic field intensity, but due to their complex thermal histories also contain other magnetic grains, which can complicate and obscure paleointensity determination. An initial study of the suitability of the ~767 ka Bishop Tuff for measuring paleointensity found an internally consistent estimate of 43.0 ± 3.2 μT. This initial study also showed a spatial heterogeneity in reliable paleointensity estimates that is possibly associated with vapor‐phase alteration and fumarolic activity, which motivated resampling of the Bishop Tuff to examine spatial changes in magnetic properties. Three new stratigraphic sections of the Bishop Tuff within the Owens River gorge were sampled, and the paleointensity results from the initial study in the same locality were reinterpreted. The mean of all sites is 41.9 ± 11.8 μT; this agrees with the initial study\u27s finding but with substantially greater scatter. Two sections show evidence of vapor‐phase alteration where the presence of titanohematite, likely carrying a thermochemical remanence, produces nonideal behavior. This thermochemical remanence in the upper portion of the section also produces some paleointensity estimates of technically high quality that have significantly higher intensity than the rest of the tuff. Our best estimate for paleointensity, 39.6 ± 9.9 μT, comes from the densely welded ignimbrite that was emplaced above the Curie temperature of magnetite. The low permeability of this unit likely shielded it from vapor‐phase alteration. Our results suggest that care must be taken in interpreting paleointensity data from large tuffs as nonthermal remanence may be present

An Overview of the Role of Systems Analysis in NASA's Hypersonics Project

NASA's Aeronautics Research Mission Directorate recently restructured its Vehicle Systems Program, refocusing it towards understanding the fundamental physics that govern flight in all speed regimes. Now called the Fundamental Aeronautics Program, it is comprised of four new projects, Subsonic Fixed Wing, Subsonic Rotary Wing, Supersonics, and Hypersonics. The Aeronautics Research Mission Directorate has charged the Hypersonics Project with having a basic understanding of all systems that travel at hypersonic speeds within the Earth's and other planets atmospheres. This includes both powered and unpowered systems, such as re-entry vehicles and vehicles powered by rocket or airbreathing propulsion that cruise in and accelerate through the atmosphere. The primary objective of the Hypersonics Project is to develop physics-based predictive tools that enable the design, analysis and optimization of such systems. The Hypersonics Project charges the systems analysis discipline team with providing it the decision-making information it needs to properly guide research and technology development. Credible, rapid, and robust multi-disciplinary system analysis processes and design tools are required in order to generate this information. To this end, the principal challenges for the systems analysis team are the introduction of high fidelity physics into the analysis process and integration into a design environment, quantification of design uncertainty through the use of probabilistic methods, reduction in design cycle time, and the development and implementation of robust processes and tools enabling a wide design space and associated technology assessment capability. This paper will discuss the roles and responsibilities of the systems analysis discipline team within the Hypersonics Project as well as the tools, methods, processes, and approach that the team will undertake in order to perform its project designated functions

Caddisflies (Trichoptera) of the Buffalo National River, Arkansas

We report 106 species of caddisflies (Trichoptera) representing 44 genera and 16 families that were collected across 50 sampling sites in the Buffalo River watershed. The species collected represent about 45% of the known Interior Highlands caddisfly fauna. The most speciose families collected were the Hydroptilidae (30), Leptoceridae (21), and Hydropsychidae (17). Two species found during this study, Paduniella nearctica and Ochrotrichia contorta, are listed as species of special concern in the state of Arkansas due to their relative rarity. Similarity analysis values among collection sites ranged from 9% to 77%. Seriation analysis of caddisfly genera and species showed that most are distributed throughout the entire Buffalo National River but some are restricted to either the upper or lower river or its tributaries. This represents the first comprehensive survey of caddisflies completed for the Buffalo National River

Cooling rate effects on paleointensity estimates in submarine basaltic glass and implications for dating young flows

Cooling rate effects on the intensity of thermoremanent magnetization (TRM) have been well documented in ceramics. In that case, laboratory cooling is generally more rapid than the initial cooling, leading to an overestimate of the paleofield by 5-10% in Thellier-type paleointensity experiments. The reverse scenario, however, has never been tested. We examine the effects of cooling rate on paleointensity estimates from rapidly quenched submarine basaltic glass (SBG) samples from 13 sites at 17°30'-18°30'S on the East Pacific Rise. Absolute cooling rates determined by relaxation geospeedometry at five of these sites range from ~10 to ~330°C min⁻¹ at the glass transition (~650°C). Over the dominant range of remanence blocking temperatures (~200-400°C), the natural cooling rates are approximately equal to or slightly slower than the laboratory cooling rates during the Thellier experiment. These results suggest that while the cooling rate effect might introduce some within-site scatter, it should not result in a systematic bias in paleointensity from SBG. Paleointensity estimates from the 15 sites range from ~29 to 59μT, with an average standard error of ~1μT. Comparison with models of geomagnetic field intensity variations at the site indicate the youngest group of samples is very recent (indistinguishable from present-day) and the oldest is at least 500, and probably several thousand, years old. These age estimates are consistent with available radiometric ages and geologic observations