1,035,534 research outputs found

    NPEFix: Automatic Runtime Repair of Null Pointer Exceptions in Java

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    Null pointer exceptions, also known as null dereferences are the number one exceptions in the field. In this paper, we propose 9 alternative execution semantics when a null pointer exception is about to happen. We implement those alternative execution strategies using code transformation in a tool called NPEfix. We evaluate our prototype implementation on 11 field null dereference bugs and 519 seeded failures and show that NPEfix is able to repair at runtime 10/11 and 318/519 failures

    The canonical Luminous Blue Variable AG Car and its neighbor Hen 3-519 are much closer than previously assumed

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    The strong mass loss of Luminous Blue Variables (LBVs) is thought to play a critical role in massive-star evolution, but their place in the evolutionary sequence remains debated. A key to understanding their peculiar instability is their high observed luminosities, which often depends on uncertain distances. Here we report direct distances and space motions of four canonical Milky Way LBVs---AG~Car, HR~Car, HD~168607, and (candidate) Hen~3-519---from the Gaia first data release. Whereas the distances of HR~Car and HD~168607 are consistent with previous literature estimates within the considerable uncertainties, Hen~3-519 and AG~Car, both at ∌\sim2~kpc, are much closer than the 6--8~kpc distances previously assumed. As a result, Hen~3-519 moves far from the locus of LBVs on the HR Diagram, making it a much less luminous object. For AG~Car, considered a defining example of a classical LBV, its lower luminosity would also move it off the S~Dor instability strip. Lower luminosities allow both AG~Car and Hen~3-519 to have passed through a previous red supergiant phase, lower the mass estimates for their shell nebulae, and imply that binary evolution is needed to account for their peculiarities. These results may also impact our understanding of LBVs as potential supernova progenitors and their isolated environments. Improved distances will be provided in the Gaia second data release, which will include additional LBVs. AG~Car and Hen~3-519 hint that this new information may alter our traditional view of LBVs.Comment: 15 pages, 2 figures, 1 table. Accepted by Astronomical Journa

    Optimal sizing of C-type passive filters under non-sinusoidal conditions

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    In the literature, much attention has been focused on power system harmonics. One of its important effects is degradation of the load power factor. In this article, a C-type filter is used for reducing harmonic distortion, improving system performance, and compensating reactive power in order to improve the load power factor while taking into account economic considerations. Optimal sizing of the C-type filter parameters based on maximization of the load power factor as an objective function is determined. The total installation cost of the C-type filter and that of the conventional shunt (single-tuned) passive filter are comparatively evaluated. Background voltage and load current harmonics are taken into account. Recommendations defined in IEEE standards 519-1992 and 18-2002 are taken as the main constraints in this study. The presented design is tested using four numerical cases taken from previous publications, and the proposed filter results are compared with those of other published techniques. The results validate that the performance of the C-type passive filter as a low-pass filter is acceptable, especially in the case of lower short-circuit capacity systems. The C-type filter may achieve the same power factor with a lower total installation cost than a single-tuned passive filter

    Missing Persons Bulletin, Iowa Department of Public Safety, January 2001

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    Monthly newsletter for public safet

    Inkjet4Tex: Creative implications of 3D inkjet printing technologies for textiles

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    This project expands future applied-design capabilities for textiles as a function of inkjet deposition technology. The project investigates 3D inkjet rapid-production tools’ potential, focusing on creative gaps in the developing technology in its application to the textile design process. As such, the research investigates future design possibilities for inkjet printing technology in the creation of 3D textile structures and surfaces. The research “demonstrates how tacit knowledge can be employed, observed and created in a methodical way, with new artefacts playing a role in provoking insights based on tacit understanding”
 [with a ] focus on developing and employing tacit insights that would not be revealed in situations where nothing has been changed.” (Rust, 2007) As inkjet textile technology evolves past a rapid prototyping tool into a series of responsive manufacturing techniques for textile products, designers, textile technology developers and soft goods industries will be able to use the results of this research to maximize their creative development. By developing and employing modified 2D/3D textile design processes with the technology future creators will be assisted to conceptualise and manufacture locally, creatively and with more accessible technologies. Keywords: 3D textiles, surface design, technology-driven design process, inkjet printing, fused deposition modelling, novel textile design</p

    Irish nationalism and the Israel-Palestinian conflict

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    Mme de Graffigny’s story

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    This article argues that Graffigny's "Lettres d'une PĂ©ruvienne" and "CĂ©nie" tell essentially the same story, that of a woman sundered from her high estate and her betrothed. The pattern of interpersonal relations is present already in Graffigny's "Nouvelle espagnole" and "La Princesse Azerolle". Graffigny's correspondence shows that this is a mythical version of her own story. Crises in 1743–44 involving her lover, her confidant, and her niece immediately precede the creation of her principal works. Her discovery in 1743 of Garcilaso's "Histoire des Incas" is associated with ‘amitié’ and with ‘amour’

    Your Right as a Trans Person

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    A guide to creating authentic space

    On vector potential of the Coulomb gauge

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    The question of an instantaneous action (A M Stewart 2003 Eur. J. Phys. 24, 519) can be approached in a systematic way applying the Helmhotz vector decomposition theorem to a two-parameter Lorenz-like gauge. We thus show that only the scalar potential may act instantaneously.Comment: REVTEX4, 7 page