132 research outputs found
"Buona Domenica" (1980-1995). The Linguistic Phenomena in the letters of Italians in Luxembourg and Great Region
Precursor Experiments Regarding the Generation of High- Frequency Gravitational Waves (HFGW) by Means of Using an Array of Micro-and Nano-Devices
Abstract. In this paper a series of proof-of-concept, precursor experiments are identified. Three specific componentvalidation, laboratory experimental tasks are described: the f irst involves the generation of a series of microsecond, nanosecond, and picosecond current pulses utilizing off-the-shelf pulse generators and even shorter pulses utilizing stateof-the-art equipment. It is recognized that the power of the HFGW generation is inversely proportional to the square of the pulse length, ?t, so that short pulse length (and high frequency of a train of pulses) is most desirable. The second task is to utilize the aforementioned pulses to energize, jerk, or otherwise cause a third-time-derivative change in motion of a test mass, termed an energizable element. The third task involves the ability to measure the motion of the test mass at megahertz, gigahertz, terahertz and other higher vibrational or jerk frequencies. Specific off-the-shelf laboratory equipment and their cost are listed. The energizing elements will involve small coils, activated by current pulses and/or electromagnetic pulses, to energize a small magnet and laser pulses to energize a small mirror or other target and other energizing elements to energize other energizable nano-or micro-devices. Once the mechanism for producing the jerk is validated in these tasks (by verifying that the energizing pulses or elements energize or jerk of the energizable element), then that mechanism can be replicated. Those replicated mechanisms can be utilized as micro-or nano-elements in devices that will be now capable of generating HFGW. In this regard, an attosecond-pulse-duration, 6 kW HFGW generator, consisting of stacks of rings of juxtaposed energizable elements, is discussed
Characterisation of the porous structure of Gilsocarbon graphite using pycnometry, cyclic porosimetry and void-network modeling
file: :C:/pdf/1-s2.0-S000862231400164X-main.pdf:pdfThe cores of the fourteen Advanced Gas-cooled nuclear Reactors (AGRs) within the UK comprise Gilsocarbon graphite, a manufactured material surrounded predominantly by CO2 at high pressure and temperature to provide heat exchange. The intense ionising radiation within the reactors causes radiolytic oxidation, and the resulting mass loss is a primary factor in determining reactor lifetime. The void structure of the porous Gilsocarbon graphite affects the permeability and diffusion of the carbon dioxide, and the sites of oxidation. To model this void structure, the porosities and densities of ten virgin Gilsocarbon graphite samples have been measured by powder and helium pycnometry. For comparison, results are also presented for highly ordered pyrolytic graphite (HOPG), and a fine-grained Ringsdorff graphite. Samples have been examined at a range of magnifications by electron microscopy. Total porosities and percolation characteristics have been measured by standard and cyclic mercury porosimetry up to an applied mercury pressure of 400MPa. Inverse modelling of the cyclic intrusion curves produces simulated void structures with characteristics which closely match those of experiment. Void size distributions of the structures are presented, together with much Supplementary Information. The simulated void networks provide the bases for future simulations of the radiolytic oxidation process itself
Dense Antihydrogen: Its Production and Storage to Envision Antimatter Propulsion
We discuss the possibility that dense antihydrogen could provide a path
towards a mechanism for a deep space propulsion system. We concentrate at
first, as an example, on Bose-Einstein Condensate (BEC) antihydrogen. In a
Bose-Einstein Condensate, matter (or antimatter) is in a coherent state
analogous to photons in a laser beam, and individual atoms lose their
independent identity. This allows many atoms to be stored in a small volume. In
the context of recent advances in producing and controlling BECs, as well as in
making antihydrogen, this could potentially provide a revolutionary path
towards the efficient storage of large quantities of antimatter, perhaps
eventually as a cluster or solid.Comment: 12 pages, 3 figure
Microstructural Evolution of Cr-Rich ODS Steels as a Function of Heat Treatment at 475 °C
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Development of design and simulation model and safety study of large-scale hydrogen production using nuclear power.
Before this LDRD research, no single tool could simulate a very high temperature reactor (VHTR) that is coupled to a secondary system and the sulfur iodine (SI) thermochemistry. Furthermore, the SI chemistry could only be modeled in steady state, typically via flow sheets. Additionally, the MELCOR nuclear reactor analysis code was suitable only for the modeling of light water reactors, not gas-cooled reactors. We extended MELCOR in order to address the above deficiencies. In particular, we developed three VHTR input models, added generalized, modular secondary system components, developed reactor point kinetics, included transient thermochemistry for the most important cycles [SI and the Westinghouse hybrid sulfur], and developed an interactive graphical user interface for full plant visualization. The new tool is called MELCOR-H2, and it allows users to maximize hydrogen and electrical production, as well as enhance overall plant safety. We conducted validation and verification studies on the key models, and showed that the MELCOR-H2 results typically compared to within less than 5% from experimental data, code-to-code comparisons, and/or analytical solutions
International Forum on Space Technology and Applications: Embarking on the New Age of Exploration Together
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