3,794 research outputs found
Semiconductor optical amplifiers in avionics
RSOAs have been demonstrated to operate within a WDM PON architectures over a >;60nm wavelength range with large path loss capabilities. Two RSOAs enable contiguous operation over the S, C and L bands; results indicate clearly that WDM architectures suitable for avionics with a PLC of >;25dB are possible with only two devices. Performance at extended temperature ranges will be reported later in detai
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Energy production and COâ‚‚ storage through multiphase flow experiments in hydrate systems
Gas hydrate is a solid ice-like compound composed of water and gas. In porous media at low temperatures, high pressures, and with sufficient gas, hydrate will form. Hydrate will occupy a fraction of the pore space, which greatly impacts the petrophysical and geomechanical properties of the system. This study investigates the morphology of gas hydrate within porous media and its impact on multiphase fluid flow behavior in these systems. To explore these impacts, I develop a method for forming hydrates in porous media and then perform systematic flow experiments on the hydrate-bearing samples. I first perform two-phase (water and hydrate) and three-phase (gas, water, and hydrate) relative permeability experiments. Through these experiments, I show that in hydrate systems water will always be the wetting phase and gas and hydrate will be the non-wetting phases. I then present a modeling framework for relative permeability in the presence of hydrate that is based on the porous media's characteristics and thermodynamically preferred pore occupancy, unlike most previous models that have fixed pore and tube geometry assumptions. By using the pore occupancy and treating hydrate as a fluid phase, the relative permeability of hydrate-bearing systems can be predicted from measurements of hydrate-free sediment. Lastly, I explore the potential of CHâ‚„ hydrate reservoirs for simultaneous energy production and COâ‚‚ storage. Using a sand-packed 7.6-meter tube saturated with CHâ‚„ hydrate and water, I inject flue gas (COâ‚‚+CHâ‚„) and observe the dissociation of CHâ‚„ hydrate and subsequent formation of COâ‚‚ hydrate. Chromatographic analysis of the effluent gas unveils the formation of distinct compositional zones during this reactive transport process. These experiments illuminate a solidification and dissociation process where hydrate replacement is composed of a complex series of steps that is driven by the combination of fluid flow and thermodynamics. This dissertation advances the understanding of multiphase flow dynamics that are critical to the lifecycle of hydrate systems on both geologic and production timescales. It offers enhanced modeling of multiphase fluid flow and carbon exchange within hydrate systems, which are relevant to other geologic systems like permafrost.Geological Science
Mr. Justice Jackson, Free Speech, and the Judicial Function
All free speech cases decided by the United States Supreme Court are hard cases; and, if they do not, according to the old saw, make bad law, they do make law which is both fragile and fascinating. Wrapped up inside the kernel of each of these cases are many of the most troublesome problems which confront a democratic government: the relation of majority rule to minority rights, the necessity of peace and order but the equally imperative necessity of open discussion, and, not least, the paradoxical role of an appointive judiciary in curbing, in the name of democracy and freedom, popularly elected legislative and executive officials. In the determination of this area of public policy, legal precedent is more shadow than substance; and the political philosophy of the individual justice becomes a matter not only of interest, but of paramount importance
Life and The Wall
I spent four years living in Berlin, Germany and I have always been fascinated by the idea of the Berlin wall. Not the historic significance of the wall – that is more than well documented – but it’s significance on the life and mentality of Berliners and Germans from both sides. My school was located in Potsdam, former East Germany, but my home was located in Mitte, former West Berlin. For four years I travelled to the former East almost daily. Although the country has long since reunified, something about the former East and the former West still feels very different. Because of this, I have always wondered how different it was when the wall was up. I have also always been fascinated and puzzled by the resentment I have heard toward “Ossis” that was widespread in West Berlin. Kids with whom I was friends who had no reason to resent former citizens of East Berlin used the term as a regular insult. Where did this come from? These were the driving questions that initiated and helped me form this project. I set out to learn what life in a Siamese city actually looked like, and how it was possible for two distant worlds to come together again
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