Institution
Sandia National Laboratories
Facility•Livermore, California, United States•
About: Sandia National Laboratories is a facility organization based out in Livermore, California, United States. It is known for research contribution in the topics: Laser & Thin film. The organization has 21501 authors who have published 46724 publications receiving 1484388 citations. The organization is also known as: SNL & Sandia National Labs.
Topics: Laser, Thin film, Hydrogen, Combustion, Silicon
Papers published on a yearly basis
Papers
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TL;DR: In this article, the effects of charge dilution on low-temperature diesel combustion and emissions were investigated in a small-bore single-cylinder diesel engine over a wide range of injection timing.
Abstract: The effects of charge dilution on low-temperature diesel combustion and emissions were investigated in a small-bore single-cylinder diesel engine over a wide range of injection timing. The fresh air was diluted with additional N 2 and CO 2 , simulating 0 to 65% exhaust gas recirculation in an engine. Diluting the intake charge lowers the flame temperature T due to the reactant being replaced by inert gases with increased heat capacity. In addition, charge dilution is anticipated to influence the local charge equivalence ratio Φ prior to ignition due to the lower O 2 concentration and longer ignition delay periods. By influencing both Φ and T, charge dilution impacts the path representing the progress of the combustion process in the Φ-T plane, and offers the potential of avoiding both soot and NO x formation. In-cylinder pressure measurements, exhaust-gas emissions, and imaging of combustion luminosity were performed to clarify the path of the combustion process and the effects of charge dilution and injection timing on combustion and fuel conversion efficiency. Based on the findings, a postulated combustion process in the Φ-T plane is presented for different dilution levels and injection timings. Although the ignition delay increased with high dilution and early injection, the heat release analysis indicated that a large portion of the combustion and emissions formation processes was still dominated by the mixing-controlled phase rather than the premixed phase. Because of the incomplete premixing, and the need to mix a greater volume of charge with unbumed or partially-burned fuel to complete combustion, the diluted mixtures increased CO emissions. Injecting the fuel at earlier timings to extend the ignition delay helped alleviate this problem, but did not eliminate it. Fuel conversion efficiencies calculated for each dilution level and start of injection provide guidance as to the appropriate combustion phasing and practical levels of charge dilution for this low-temperature diesel combustion regime.
350 citations
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TL;DR: In this article, a vertical-cavity surface emitting laser fabricated using selective oxidation to form a current aperture under a top monolithic distributed Bragg reflector mirror is reported.
Abstract: Novel vertical-cavity surface emitting lasers fabricated using selective oxidation to form a current aperture under a top monolithic distributed Bragg reflector mirror are reported. Large cross-sectional area lasers (259 µm2) exhibit threshold current densities of 150 A/cm2 per quantum well and record low threshold voltage of 1.33 V. Smaller lasers (36 µm2) possess threshold currents of 900 µA with maximum output powers greater than 1 mW. The record performance of these oxidised vertical-cavity lasers arises from the low mirror series resistance and very efficient current injection into the active region.
349 citations
01 Nov 1978
TL;DR: The testability of a digital circuit is directly related to the difficulty of controlling and observing the logical values of internal nodes from circuit inputs and outputs, respectively as discussed by the authors, and the testability is also related to how well the internal nodes can be controlled and observed.
Abstract: The testability of a digital circuit is directly related to the difficulty of controlling and observing the logical values of internal nodes from circuit inputs and outputs, respectively. This paper presents a method for analyzing digital circuits in terms of six functions which characterize combinational and sequential controllability and observability.
349 citations
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TL;DR: The development of current soft magnetic materials and opportunities for improving their performance in high-frequency operation are reviewed, including soft ferrites, amorphous and nanocrystalline alloys, and powder cores or soft magnetic composites.
Abstract: Soft magnetic materials are key to the efficient operation of the next generation of power electronics and electrical machines (motors and generators). Many new materials have been introduced since Michael Faraday's discovery of magnetic induction, when iron was the only option. However, as wide bandgap semiconductor devices become more common in both power electronics and motor controllers, there is an urgent need to further improve soft magnetic materials. These improvements will be necessary to realize the full potential in efficiency, size, weight, and power of high-frequency power electronics and high-rotational speed electrical machines. Here we provide an introduction to the field of soft magnetic materials and their implementation in power electronics and electrical machines. Additionally, we review the most promising choices available today and describe emerging approaches to create even better soft magnetic materials.
349 citations
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TL;DR: In this paper, a thermodynamische Theorie of nichteinfachen, elastischen Stoffen wird gezeigt, dass Substanzen vom Grade hoher als eins vorkommen konnen; vorausgesetzt, man das eventuelle Vorhandensein zweier verschiedener Temperaturen in Betracht zieht.
Abstract: Diese Arbeit behandelt eine thermodynamische Theorie von nichteinfachen, elastischen Stoffen Es wird gezeigt, dass Substanzen vom Grade hoher als eins vorkommen konnen; vorausgesetzt, dass man das eventuelle Vorhandensein zweier verschiedener Temperaturen in Betracht zieht
349 citations
Authors
Showing all 21652 results
Name | H-index | Papers | Citations |
---|---|---|---|
Lily Yeh Jan | 162 | 467 | 73655 |
Jongmin Lee | 150 | 2257 | 134772 |
Jun Liu | 138 | 616 | 77099 |
Gerbrand Ceder | 137 | 682 | 76398 |
Kevin M. Smith | 114 | 1711 | 78470 |
Henry F. Schaefer | 111 | 1611 | 68695 |
Thomas Bein | 109 | 677 | 42800 |
David Chandler | 107 | 424 | 52396 |
Stephen J. Pearton | 104 | 1913 | 58669 |
Harold G. Craighead | 101 | 569 | 40357 |
Edward Ott | 101 | 669 | 44649 |
S. Das Sarma | 100 | 951 | 58803 |
Richard M. Crooks | 97 | 419 | 31105 |
David W. Murray | 97 | 699 | 43372 |
Alán Aspuru-Guzik | 97 | 628 | 44939 |