3,940 research outputs found
The Distribution of Loads Between the Wings of a Biplane Having Decalage
It is known that in a biplane the load is not distributed equally between the wings. The presence of one wing will affect the lift characteristics of the other wings. A designer must know the total load that each wing carries in order that he may design an adequate structure. The purpose here is to determine the distribution of loads between the wings of a biplane at various angles of decalage, when the gap/chord ratio is one, and there is no stagger. The effective lift of each wing was first investigated, using the vortex theory, and later by wind tunnel experiments. The results are given in tabular form
Anisotropy, phonon modes, and lattice anharmonicity from dielectric function tensor analysis of monoclinic cadmium tungstate
We determine the frequency dependence of four independent CdWO Cartesian
dielectric function tensor elements by generalized spectroscopic ellipsometry
within mid-infrared and far-infrared spectral regions. Single crystal surfaces
cut under different angles from a bulk crystal, (010) and (001), are
investigated. From the spectral dependencies of the dielectric function tensor
and its inverse we determine all long wavelength active transverse and
longitudinal optic phonon modes with and symmetry as well as their
eigenvectors within the monoclinic lattice. We thereby demonstrate that such
information can be obtained completely without physical model line shape
analysis in materials with monoclinic symmetry. We then augment the effect of
lattice anharmonicity onto our recently described dielectric function tensor
model approach for materials with monoclinic and triclinic crystal symmetries
[Phys. Rev. B, 125209 (2016)], and we obtain excellent match between all
measured and modeled dielectric function tensor elements. All phonon mode
frequency and broadening parameters are determined in our model approach. We
also perform density functional theory phonon mode calculations, and we compare
our results obtained from theory, from direct dielectric function tensor
analysis, and from model lineshape analysis, and we find excellent agreement
between all approaches. We also discuss and present static and above
reststrahlen spectral range dielectric constants. Our data for CdWO are in
excellent agreement with a recently proposed generalization of the
Lyddane-Sachs-Teller relation for materials with low crystal symmetry [Phys.
Rev. Lett. 117, 215502 (2016)].Comment: arXiv admin note: text overlap with arXiv:1512.0859
Anisotropy and phonon modes from analysis of the dielectric function tensor and inverse dielectric function tensor of monoclinic yttrium orthosilicate
We determine the frequency dependence of the four independent Cartesian
tensor elements of the dielectric function for monoclinic symmetry YSiO
using generalized spectroscopic ellipsometry from 40-1200 cm. Three
different crystal cuts, each perpendicular to a principle axis, are
investigated. We apply our recently described augmentation of lattice
anharmonicity onto the eigendielectric displacement vector summation approach
[A. Mock et al., Phys. Rev. B 95, 165202 (2017)], and we present and
demonstrate the application of an eigendielectric displacement loss vector
summation approach with anharmonic broadening. We obtain excellent match
between all measured and model calculated dielectric function tensor elements
and all dielectric loss function tensor elements. We obtain 23 A
and 22 B symmetry long wavelength active transverse and
longitudinal optical mode parameters including their eigenvector orientation
within the monoclinic lattice. We perform density functional theory
calculations and obtain 23 A symmetry and 22 B
transverse and longitudinal optical mode parameters and their orientation
within the monoclincic lattice. We compare our results from ellipsometry and
density functional theory and find excellent agreement. We also determine the
static and above reststrahlen spectral range dielectric tensor values and find
a recently derived generalization of the Lyddane-Sachs-Teller relation for
polar phonons in monoclinic symmetry materials satisfied [M. Schubert, Phys.
Rev. Lett. 117, 215502 (2016)]
WeakSATD: Detecting Weak Self-admitted Technical Debt
Speeding up development may produce technical debt, i.e., not-quite-right code for which the effort to make it right increases with time as a sort of interest. Developers may be aware of the debt as they admit it in their code comments. Literature reports that such a self-admitted technical debt survives for a long time in a program, but it is not yet clear its impact on the quality of the code in the long term. We argue that self-admitted technical debt contains a number of different weaknesses that may affect the security of a program. Therefore, the longer a debt is not paid back the higher is the risk that the weaknesses can be exploited. To discuss our claim and rise the developers' awareness of the vulnerability of the self-admitted technical debt that is not paid back, we explore the self-admitted technical debt in the Chromium C-code to detect any known weaknesses. In this preliminary study, we first mine the Common Weakness Enumeration repository to define heuristics for the automatic detection and fix of weak code. Then, we parse the C-code to find self-admitted technical debt and the code block it refers to. Finally, we use the heuristics to find weak code snippets associated to self-admitted technical debt and recommend their potential mitigation to developers. Such knowledge can be used to prioritize self-admitted technical debt for repair. A prototype has been developed and applied to the Chromium code. Initial findings report that 55% of self-admitted technical debt code contains weak code of 14 different types
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