Thermodynamics of a Rotating Detonation Engine

A practical thermodynamic cycle model of a rotating detonation engine (RDE) is developed for the purpose of predicting performance and understanding flow field behavior. The cycle model is based on a heuristic analysis of a RDE numerical simulation. The model is compared to the simulation and to laboratory experiment with good results. The RDE constrains a detonation wave to rotate inside a cylindrical annulus, has no moving parts and requires a single ignition sequence. Thrust is produced continuously and at high frequency. The simplicity of the RDE offers the possibility of a practical detonation engine with efficiencies that exceed conventional Brayton cycles. A RDE numerical simulation (courtesy of the Naval Research Laboratory) is post-processed to yield the underlying thermodynamics. The time-accurate numerical simulation is averaged over many cycles. A Galilean transformation is applied to the time-averaged solution to produce a solution field in the rotating frame of reference. Streamlines are created in the transformed solution field. Velocity, pressure and temperature are extracted along the streamlines. Pressure-volume and enthalpy-entropy diagrams are plotted to expose the simulation thermodynamics. The results are found to be consistent with the conservation of rothalpy as the fundamental statement of the conservation of energy in a rotating frame of reference. The signature of rothalpy in the RDE is shown to be a small amount of azimuthal flow or swirl. The change in flow field swirl is shown to be proportional to the change in stagnation enthalpy and consistent with the Euler turbomachinery equation. The simulation analysis supports the construction of an analytical model based on a modified ZND (Zel’dovich-von Neumann-Döring) detonation theory. This theory is combined with the concept of rothalpy. The result is a realistic thermodynamic cycle model with a theoretical basis for performance prediction and an explanation of the flow field structure. The RDE cycle model is analytical, thermodynamically one-dimensional, steady-state, and independent of geometry and heat release rate. The performance of the modified ZND cycle model is within 3% of the numerical simulation and in good quantitative agreement with experimental test results at the Air Force Research Laboratory Detonation Engine Research Facility

The influence of high-amplitude acoustic deterrents on the distribution, abundance, and behaviour of baleen whales

The influence of high-amplitude acoustic deterrents (HAADs) on mysticetes, including humpback whales (Megaptera novaeangliae), fin whales (Balaenoptera physalus), and minke whales (B. acutorostrata), was investigated at Cape Saint Francis, Newfoundland, Canada during the summers of 1995 and 1996. The influence of HAADs on baleen whale distribution, abundance, and behaviour was evaluated by shore-based monitoring of a study site. A HAADs system was moored inshore at a water depth of 10m and the average sound pressure level of these pulses was 194 dB re luPa at 1 m with energy concentrated around 10 kHz and a single harmonic at 20 kHz. The acoustic device was randomly operated on a 24 hour basis (either 'on' or 'off). Observers stationed on a 60m cliff documented species, number of individuals, behaviour and presence/absence of vessels in the area with each whale sighting throughout the day. Whale movements were tracked with a theodolite and observers were unaware of the operating condition of HAADs. The distance between whale sightings and HAADs was quantified to determine whale distribution, sighting rate was calculated as a measure of abundance, and the proportion of behaviours were compared between operating condition of HAADS. Results indicated that operation of HAADs was significantly related to the distribution and abundance of baleen whales and may relate to transient and residential species differently. Despite considerable variation in the number of whale sightings between years, overall distance and sighting trends suggest that humpback and fin whales demonstrated an avoidance of operating HAADs while minke whales exhibited no influence and/or an attraction to operating HAADs. This result suggests that transient whale species are displaced from areas with operating HAADs, while resident species remain in areas with operating HAADs. To mitigate any possible influences on baleen whales from HAADs, deterrent usage could be seasonally adjusted to avoid biologically important habitats and high concentrations of whales

Systems Integration for the Kennedy Space Center (KSC) Robotics Applications Development Laboratory (RADL)

Robotics technology is a rapidly advancing field moving from applications on repetitive manufacturing processes toward applications of more variable and complex tasks. Current directions of NASA designs for the Space Station and other future spacecraft is moving toward the use of robotics for operational, maintenance and repair functions while the spacecraft is in orbit. These spacecraft systems will eventually require processing through KSC for launch and refurbishment. In the future, KSC will be called on to design ground processing facilities for new generation launch vehicles such as the Heavy Lift Launch Vehicle and the Second Generation Shuttle. The design of these facilities should take advantage of stateof- the-art robotics technology to provide the most efficient and effective vehicle processing. In addition to these future needs for robotics technology expertise, it is readily apparent that robotics technology could also have near-term applications to some of the existing hazardous and repetitive Shuttle and payload processing activities at KSC

Speech Perception Across the Lifespan: Using a Gaussian Mixture Model toUnderstand Changes in Cue Weighting Between Younger and Older Adults

In order to understand speech, listeners must weight and combine multiple acoustic cues. For example, voiceonset time (VOT) is a reliable cue to stop consonant voicing, while onset F0 provides information, but is much less reliable.Consequently, we would expect listeners to weight VOT higher than F0. This is the pattern observed for most listeners.However, these cue weights also change over time, and older adults tend to rely less on VOT than young adults, even inlisteners without hearing loss. One hypothesized mechanism for this change is a decreased ability to detect temporal differencesin sounds, which renders temporal cues (e.g., VOT) less reliable and leads to a greater reliance on spectral information (F0). Wesimulate this using a weighted Gaussian mixture model and find evidence in support of this mechanism: decreased temporalcue reliability leads to the same pattern of differences observed between younger and older listeners

Characterization of Bacteriophages of Pseudomonas syringae pv. tomato

Bacteriophages from supernatants of the plant pathogenic bacteria Pseudomonas syringae pv. tomato (P. tomato) were isolated, enriched, and purified by density block centrifugation in cesium chloride (CsCl) step gradients. The DNA from purified phage was isolated and digested with the restriction endonucleases EcoRl or HindIII. Three different DNA fingerprint patterns were determined indicating 3 unique phage isolates. Genome sizes of the phage ranged from 40 to 52 kilobases (kB). Buoyant densities of phage particles in CsCI varied from 1.36 to 1.51 glml. Electron microscopy revealed a single morphological type with an elongated polyhedral head and a long tail indicating the family Siphovirida

Design and Synthesis of Potential TLR7 and TLR8 Inhibitors

Toll-like receptors (TLRs) detect invading viral and bacterial pathogens and play a critical role in the initiation and regulation of the innate immune system. Over-active TLR signaling has been indicated in the disease pathology of numerous crippling inflammatory autoimmune disorders and inhibition of these receptors is of considerable interest for therapeutic intervention. TLR7 and TLR8 are the two TLRs that share the most similarity in both sequence and structure. Despite their similarity, selective inhibition represents a promising therapy for diseases such as systemic lupus erythematosus (lupus) and rheumatoid arthritis (RA). The goal of this master’s thesis is to identify small molecule inhibitors of TLR7 and TLR8 through the use of structure-activity relationship (SAR) studies and the synthesis of a diverse and complex library based around the native ligands of these receptors. Chapter 1 begins with a brief overview of TLR structure, function, and signaling. Next TLR7 and TLR8 will be discussed including the role they play in lupus and RA as well as the current state of TLR7/8 inhibitors. Chapter 2 discusses the synthesis of TLR8 inhibitors, identified from a cell-based high-throughput screen (HTS). A series of 14 analogs were synthesized with the aim of improving TLR8 inhibition. Chapter 3 focuses on the development of a diverse and complex library based around the native ligands of these receptors. The justification, feasibility, research design, and progress will be discussed. Finally, chapters 4 and 5 are the experimental and characterization of the compounds synthesized in these projects