18,076 research outputs found
An accurate formula for the period of a simple pendulum oscillating beyond the small-angle regime
A simple approximation formula is derived here for the dependence of the
period of a simple pendulum on amplitude that only requires a pocket calculator
and furnishes an error of less than 0.25% with respect to the exact period. It
is shown that this formula describes the increase of the pendulum period with
amplitude better than other simple formulas found in literature. A good
agreement with experimental data for a low air-resistance pendulum is also
verified and it suggests, together with the current availability/precision of
timers and detectors, that the proposed formula is useful for extending the
pendulum experiment beyond the usual small-angle oscillations.Comment: 15 pages and 4 figures. to appear in American Journal of Physic
Awaking the vacuum with spheroidal shells
It has been shown that well-behaved spacetimes may induce the vacuum
fluctuations of some nonminimally coupled free scalar fields to go through a
phase of exponential growth. Here, we discuss this mechanism in the context of
spheroidal thin shells emphasizing the consequences of deviations from
spherical symmetry.Comment: 10 pages, 7 figures. Minor changes, version published on Phys. Rev.
Explainable Metamodels for ATM Performance Assessment
Fast-time simulation constitutes a well-known and
long-established technique within the Air Traffic Management
(ATM) community. However, it is often the case that simulation input and output spaces are underutilized, limiting the full understandability, transparency, and interpretability of the obtained results.
In this paper, we propose a methodology that combines simulation metamodeling and SHapley Additive exPlanations (SHAP) values, aimed at uncovering the intricate hidden relationships among the input and output variables of a simulated ATM system in a rather practical way. Whereas metamodeling provides explicit functional approximations mimicking the behavior of the simulators, the SHAP-based analysis delivers a systematic framework for improving their explainability. We illustrate our approach using a state-of-the-art ATM simulator across two case studies in which two delay-centered performance metrics are analyzed. The results show that the proposed methodology can effectively make simulation and its results more explainable, facilitating the interpretation of the obtained emergent behavior, and additionally opening new opportunities towards novel performance assessment processes within the ATM research field
Avaliação da ferrugem da videira em variedades uvas de vinho.
O objetivo deste trabalho foi avaliar a ocorrência da ferrugem da videira em variedades de uva para vinho
Reação de cultivares e clones de batata a Meloidogyne javanica. reaction of potato cultivars and clones to Meloidogyne javanica.
Avaliação da atividade antimicrobiana do óleo essencial de Lippia alba frente ao Staphylococcus aureus, à Salmonella choleraesuis, Echerichia coli e Pseudomona aeruginosa.
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