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Showing 1 to 20 of 48 for “"Hydrogen content"”.
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Turbulent flame propagation characteristics of high hydrogen content fuels
… of modern combustors is the use of high hydrogen content (HHC) fuels. The objective of this research is to develop tools to better understand the physics of turbulent flame propagation in highly stretch sensitive premixed flames in order to predict their behavior at conditions realistic …
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Effects of hydrogen in an aluminium-magnesium-silicon alloy during the production of extrusion ingots
Hydrogen causes defects, for which aluminiurn alloy products are rejected. The behaviour of hydrogen in aluminium-magnesium-silicon alloy extrusion ingots, has been studied throughout the course of manufacture from freshly reduced aluminium. It is shown that hydrogen in the liquid metal is produced …
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Relationship between Microstructure, Properties and HICC Resistance of HSLA steel weld metals
… of microstructure, mechanical properties and hydrogen content on the hydrogen induced cold cracking (HICC) resistance of high strength low alloy (HSLA) steel weld metals were studied in this investigation. The weld metals were designed in a previous work. Their microstructures were …
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Ignition Delay Times of Natural Gas/Hydrogen Blends at Elevated Pressures
… of natural gases that contain high levels of hydrogen have become a primary interest in the gas turbine market. For reheat gas turbines, understanding of the ignition delay times of high-hydrogen natural gases is important for two reasons. First, if the ignition delay time is too short, …
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Understanding and improving hole transport in hydrogenated amorphous silicon photovoltaics
While hydrogenated amorphous silicon (a-Si:H) solar cells have been studied extensively for the previous four decades, the low performance of the devices is still not well understood. The poor efficiency (below 10%, even in research-scale devices) is believed to be mainly due to the low hole …
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Evaluation of fast neutron shielding effectiveness in light-element compounds
… of neutron absorbers relative to the hydrogen content may make a difference in the effectiveness of any shielding material. The superiority of such an approach lies in its capability to moderate neutrons via scattering process interaction with hydrogen after a small number of …
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The effect of hydration state, Fe, and spin state of Fe on the elasticity of mantle minerals at high pressure
… systematic errors in the determination of water content measured by different methods, I measured water content of wadsleyite using the Fourier Transform Infrared method. The results show that water content of wadsleyite is nearly half of that using Secondary Ion Mass spectroscope. This …
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The effect of activation on the deactivation of a precipitated iron based catalyst
… $4-13 billion to meet the proposed sulphur content requirements. Also, Fischer-Tropsch processes using coal as a feedstock could become and attractive alternative to oil refining due to the large differential between crude oil and coal prices...A study was undertaken in order to investigate …
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Development of a soft-landing system for space applications
… composition and density have limited importance. Hydrogen content influences the shape of the spectra, but it does not interfere with the backscatter peak. The simulation agrees with experiment data within 6.29%.
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In Process Measurement of Hydrogen In Welding
The deleterious effects of atomic, or diffusible, hydrogen dissolved in welds on their mechanical properties have been known for over four decades. However, post weld inspection and repair of hydrogen induced cracks in welds remains the only means of correcting the defects produced by excess …
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Development of a lithium hydride powered hydrogen generator for use in long life, low power PEM fuel cell power supplies
… due to cost, reliability, and the problem of hydrogen storage. This thesis focuses on the problem of hydrogen storage. Lithium hydride is selected for study because of its high hydrogen content and because it produces hydrogen through a chemical reaction with water. Control of the lithium …
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Polonium extraction techniques for a lead-bismuth cooled fast reactor
… species in contact with various argon and hydrogen gas streams. It was determined that the rate release of polonium hydride is slightly higher at lower temperatures. The kinetic response is also faster with increased hydrogen content, as evident by the determined equilibrium constant. In …
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Hydrogen effects on the point defect spectrum in Fe-C alloys
As part of a multi-scale approach for modeling hydrogen embrittlement in hardened steels we have investigated, employing density functional theory methods, the stability and concentrations of the point defect clusters present in metastable Fe-C-H alloys with vacancies. The defect spectrum is found …
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Density of gap states in hydrogenated amorphous silicon
… grown by an improved r.f. sputtering method in a hydrogen-argon atmosphere. Deposition parameters such as substrate temperature, gas flow rate, r.f. power, and argon partial pressure were kept constant, while hydrogen partial pressure was varied. The infrared vibrational modes, optical absorption, …
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First principles simulation of amorphous silicon bulk, interfaces, and nanowires for photovoltaics
… to generate structural models of amorphous and hydrogenated amorphous silicon and interfaces of amorphous and crystalline silicon, with the ultimate aim of understanding the photovoltaic properties of core-shell crystalline amorphous Si nanowire structures. We have shown, unexpectedly, from the …
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Hydrogen embrittlement: an interfacial phenomenon
Hydrogen transport during a test and hydrogen segregation to twins, second phase particles and precipitation products prior to testing are shown to adversely effect the mechanical properties of metals. Hydrogen embrittlement processes in austenitic stainless steel, mild steel and aluminum occurred …
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Radiation response and optical characterization of carbon based thin-films prepared by saddle field plasma enhanced chemical vapor deposition
… methods. It was found that, an increase in the hydrogen content in the gas mixture leads to a decrease in the crystallinity of the resultant film. A set of samples were selected with different crystalline content and defect DOS to investigate the impact of these parameters on the material’s …
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Evaluation of diamond-like carbon films for lubrication in space
… in space conditions. Specifically, high-hydrogenated siliconcontaining DLC coatings (a-CHSi or Si-DLC) were assessed. These coatings were produced by plasma-assisted chemical-vapour deposition (PACVD) by the supplier VITO, a Belgian research institute. Testing of the coatings was …
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Origins and implications of intrinsic stress in hydrogenated amorphous silicon thin films
Despite decades of research on hydrogenated amorphous silicon (a-Si:H), there remains much to be understood about the relationship between deposition conditions and the resulting structural, optical, and bulk properties of the material. In this work we investigate these correlations for a-Si:H …
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