10,371 research outputs found
Metal shearing energy absorber
A metal shearing energy absorber is described. The absorber is composed of a flat thin strip of metal which is pulled through a slot in a cutter member of a metal, harder than the metal of the strip. The slot's length, in the direction perpendicular to the pull direction, is less than the strip's width so that as the strip is pulled through the slot, its edges are sheared off, thereby absorbing some of the pulling energy. In one embodiment the cutter member is a flat plate of steel, while in another embodiment the cutter member is U-shaped with the slot at its base
Metal-shearing energy absorber
Device, consisting of tongue of thin aluminum alloy strip, pull tab, slotted steel plate which serves as cutter, and steel buckle, absorbs mechanical energy when its ends are subjected to tensile loading. Device is applicable as auxiliary shock absorbing anchor for automobile and airplane safety belts
Harmonic Maa{\ss}-Jacobi forms of degree 1 with higher rank indices
We define and investigate real analytic weak Jacobi forms of degree 1 and
arbitrary rank. En route we calculate the Casimir operator associated to the
maximal central extension of the real Jacobi group, which for rank exceeding 1
is of order 4. In ranks exceeding 1, the notions of H-harmonicity and
semi-holomorphicity are the same.Comment: 28 page
Integrating TV/digital data spectrograph system
A 25-mm vidicon camera was previously modified to allow operation in an integration mode for low-light-level astronomical work. The camera was then mated to a low-dispersion spectrograph for obtaining spectral information in the 400 to 750 nm range. A high speed digital video image system was utilized to digitize the analog video signal, place the information directly into computer-type memory, and record data on digital magnetic tape for permanent storage and subsequent analysis
Energy-momentum diffusion from spacetime discreteness
We study potentially observable consequences of spatiotemporal discreteness
for the motion of massive and massless particles. First we describe some simple
intrinsic models for the motion of a massive point particle in a fixed causal
set background. At large scales, the microscopic swerves induced by the
underlying atomicity manifest themselves as a Lorentz invariant diffusion in
energy-momentum governed by a single phenomenological parameter, and we derive
in full the corresponding diffusion equation. Inspired by the simplicity of the
result, we then derive the most general Lorentz invariant diffusion equation
for a massless particle, which turns out to contain two phenomenological
parameters describing, respectively, diffusion and drift in the particle's
energy. The particles do not leave the light cone however: their worldlines
continue to be null geodesics. Finally, we deduce bounds on the drift and
diffusion constants for photons from the blackbody nature of the spectrum of
the cosmic microwave background radiation.Comment: 13 pages, 4 figures, corrected minor typos and updated to match
published versio
Polarization Diffusion from Spacetime Uncertainty
A model of Lorentz invariant random fluctuations in photon polarization is
presented. The effects are frequency dependent and affect the polarization of
photons as they propagate through space. We test for this effect by confronting
the model with the latest measurements of polarization of Cosmic Microwave
Background (CMB) photons.Comment: 4 pages, 1 figur
Isotropisation of Generalized Scalar-Tensor theory plus a massive scalar field in the Bianchi type I model
In this paper we study the isotropisation of a Generalized Scalar-Tensor
theory with a massive scalar field. We find it depends on a condition on the
Brans-Dicke coupling function and the potential and show that asymptotically
the metric functions always tend toward a power or exponential law of the
proper time. These results generalise and unify these of De Sitter in the case
of a cosmological constant and of Cooley and Kitada in the case of an
exponential potential.Comment: 10 page
Determinação de herbicidas em água por enriquecimento em discos de extração.
Visando à identificação e quantificação de dezenove (19) herbicidas supostamente presentes em águas da bacia do rio Corumbataí, estado de São Paulo, Brasil, por causa do uso de agrotóxicos no cultivo predominante da região, cana de açúcar, foi desenvolvido método multiresíduos para análise desses herbicidas. A detecção e separação dos compostos foi efetuada por cromatografia gasosa com detector específico de nitrogênio e fósforo (NPD) para 8 dos herbicidas, com a utilização de coluna DB-5 30,0m x 0,25mm x 1.0µm, a qual apresentou a melhor resposta dentre as utilizadas. Por cromatografia líquida com detector ultravioleta-visível (UV-VIS) os demais herbicidas, foram separados utilizando coluna Lichrosorb RP-18, 5µm x 250mm x 4,6mm. A intenção de estabelecer método único de extração de resíduos de herbicidas trouxe a vantagem da rapidez no processo e permitiu o uso de volumes adequados de amostras, assim como a utilização de dois sistemas de detecção facilitou a separação dos analitos
Otimização da separação cromatográfica de dissulfeto de carbono para aplicação na análise de resíduos de ditiocarbamatos por CG/FPD.
Foram otimizadas as condições para separação cromatográfica de CS2 na análise de ditiocarbamatos por cromatografia gasosa utilizando detector fotométrico de chama no modo enxofre. Foram utilizadas as colunas capilares: Chrompack CP-SIL 8-CB de 5% fenil 95% metilpolisiloxano de 50m x 0,32mm x 1,2mm; Restek RTX-1, 100% dimetilpolisiloxano com 30m x 0,32mm x 4mm e a megabore de poliestireno divinilbenzeno, HP PLOT-Q de 30m x 0,53mm x 40mm. Para cada coluna foi obtido o limite de detecção de 0,05mg mL-1; 0,27mg mL-1 e 0,03mg mL-1, respectivamente. A coluna HP Plot-Q foi a que permitiu melhor quantificação do dissulfeto de carbono tendo apresentado resolução e simetria de pico muito superior as demais colunas avaliadas
Factorization of the Two Loop Four-Particle Amplitude in Superstring Theory Revisited
We study in detail the factorization of the newly obtained two-loop
four-particle amplitude in superstring theory. In particular some missing
factors from the scalar correlators are obtained correctly, in comparing with a
previous study of the factorization in two-loop superstring theory. Some
details for the calculation of the factorization of the kinematic factor are
also presented.Comment: 11 pages, 1 figure; v2, minor corrections and references update
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