Robustness and Adaptiveness Analysis of Future Fleets

Making decisions about the structure of a future military fleet is a challenging task. Several issues need to be considered such as the existence of multiple competing objectives and the complexity of the operating environment. A particular challenge is posed by the various types of uncertainty that the future might hold. It is uncertain what future events might be encountered; how fleet design decisions will influence and shape the future; and how present and future decision makers will act based on available information, their personal biases regarding the importance of different objectives, and their economic preferences. In order to assist strategic decision-making, an analysis of future fleet options needs to account for conditions in which these different classes of uncertainty are exposed. It is important to understand what assumptions a particular fleet is robust to, what the fleet can readily adapt to, and what conditions present clear risks to the fleet. We call this the analysis of a fleet's strategic positioning. This paper introduces how strategic positioning can be evaluated using computer simulations. Our main aim is to introduce a framework for capturing information that can be useful to a decision maker and for defining the concepts of robustness and adaptiveness in the context of future fleet design. We demonstrate our conceptual framework using simulation studies of an air transportation fleet. We capture uncertainty by employing an explorative scenario-based approach. Each scenario represents a sampling of different future conditions, different model assumptions, and different economic preferences. Proposed changes to a fleet are then analysed based on their influence on the fleet's robustness, adaptiveness, and risk to different scenarios

Dispersion-cancelled imaging with chirped laser pulses

This thesis deals with chirped-pulse interferometry, an interferometric imaging technique with a resolution which is unaffected by the normally detrimental effects of sample dispersion. The thesis begins with some important background definitions and concepts. The properties of ultrafast laser pulses are discussed, and the nonlinear process of sum-frequency generation is defined. Three different interferometric imaging systems introduced, namely optical coherence tomography, quantum optical coherence tomography, and chirped-pulse interferometry. Understanding the first two techniques is key to realizing the benefits provided by the third. In the first experiment a chirped-pulse interferometer is used to image the cells of an onion. This is the first time that a dispersion-cancelled technique has been used to image the interior structure of a biological sample. Laser pulses centred on 810 nm with 90 nm full-width at half-maximum bandwidth are chirped with a spatial light modulator in a 4f-system to create a superposition of frequency-anticorrelated pulses. The chirped pulses are sent into a cross-correlator with a sample of onion in one arm. The cellular structure of the onion is imaged to a depth of 0.5 mm with a resolution of 3.2 ± 0.6 μm. The introduction of 132 fs² of quadratic dispersion in front of the sample does not affect the resolution of the image. A three-dimensional image of the sample's internal structure is created. The second experiment uses a nonlinear chirping function to produce a narrower interference signal in a chirped-pulse interferometer than that given by linearly-chirped pulses; this competes with the inherently narrower signal seen in quantum optical coherence tomography systems. The nonlinear chirping function theoretically narrows the interference signal by 30%, matching the width of the quantum signal. Experimentally, a narrowing of 17% was observed. The nonlinear chirping function was shown to cancel the 132 fs² of unbalanced quadratic dispersion as effectively as the linear function. One of the main sources of background noise in a chirped-pulse interferometer is a narrow-band component of sum-frequency generated light from the interferometer's intense reference beam. This background is at the same frequency and has the same bandwidth as the signal. A third experiment is proposed in which the light in the sample and reference arms of the interferometer is chirped independently. If the light in both arms is a superposition of frequency-anticorrelated pulses with different average frequencies the interferometer should still be dispersion-cancelling, but the narrowband background will shift spectrally from the signal

Robustness and Adaptability Analysis of Future Military Air Transportation Fleets

Making decisions about the structure of a future military fleet is challenging. Several issues need to be considered, including multiple competing objectives and the complexity of the operating environment. A particular challenge is posed by the various types of uncertainty that the future holds. It is uncertain what future events might be encountered and how fleet design decisions will influence these events. In order to assist strategic decision-making, an analysis of future fleet options needs to account for conditions in which these different uncertainties are exposed. It is important to understand what assumptions a particular fleet is robust to, what the fleet can readily adapt to, and what conditions present risks to the fleet. We call this the analysis of a fleet’s strategic positioning. Our main aim is to introduce a framework that captures information useful to a decision maker and defines the concepts of robustness and adaptability in the context of future fleet design. We demonstrate our conceptual framework by simulating an air transportation fleet problem. We account for uncertainty by employing an explorative scenario-based approach. Each scenario represents a sampling of different future conditions and different model assumptions. Proposed changes to a fleet are then analysed based on their influence on the fleet’s robustness, adaptability, and risk to different scenarios

Impact of Decmedetomidine on Opioid and Benzodiazepine Dosing Requirements in Children.

Poster presented at: Annual Update on Pediatric Cardiovascular Disease; February 2008; Scottsdale Arizona

Visibility-reducing organic aerosols in the vicinity of Grand Canyon National Park: Properties observed by high resolution gas chromatography

Fine particle and total airborne particle samples were collected during August 1989 within the Grand Canyon (Indian Gardens (IG)) and on its south rim (Hopi Point (HP)) to define summertime organic aerosol concentration and composition as a function of elevation at Grand Canyon National Park. Inorganic chemical constituents were analyzed also to help place the relative importance of organics in perspective. Fine particle organic aerosols were approximately equal in concentration to sulfate aerosols at both sites. Monthly average mass concentrations for fine aerosol organics ranged from 1.1 μg m(−3) (IG) to 1.3 μg m^(−3) (HP), while the organic aerosol concentration within total suspended particulate matter samples ranged from 1.9 μg m^(−3) (IG) to 2.1 μg m^(−3) (HP). Aerosol organics that could be evaluated by gas chromatography with flame ionization detection (GC-FID) (elutable organics) constituted 27% to 53% of the total organics mass collected as fine or total aerosol. At each site, roughly half of the elutable organics fine aerosol fraction was composed of highly polar organic compounds. Distributions of the elutable organics were compared to Los Angeles fine aerosol samples and to distributions of authentic sources of aerosol organics. It was found that the Grand Canyon organic aerosol during August 1989 did not resemble diluted aged Los Angeles organic aerosol, indicating that most of the organic particulate matter at the Grand Canyon at the time studied originated from other sources