201 research outputs found
Humbert de Superville: Representing Theory
Medieval and Early Modern Studie
Modeling Affect Dynamics:State of the Art and Future Challenges
The current article aims to provide an up-to-date synopsis of available techniques to study affect dynamics using intensive longitudinal data (ILD). We do so by introducing the following eight dichotomies that help elucidate what kind of data one has, what process aspects are of interest, and what research questions are being considered: (1) single- versus multiple-person data; (2) univariate versus multivariate models; (3) stationary versus nonstationary models; (4) linear versus nonlinear models; (5) discrete time versus continuous time models; (6) discrete versus continuous variables; (7) time versus frequency domain; and (8) modeling the process versus computing descriptives. In addition, we discuss what we believe to be the most urging future challenges regarding the modeling of affect dynamics
Stiff Stability of the Hydrogen atom in dissipative Fokker electrodynamics
We introduce an ad-hoc electrodynamics with advanced and retarded
Lienard-Wiechert interactions plus the dissipative Lorentz-Dirac
self-interaction force. We study the covariant dynamical system of the
electromagnetic two-body problem, i.e., the hydrogen atom. We perform the
linear stability analysis of circular orbits for oscillations perpendicular to
the orbital plane. In particular we study the normal modes of the linearized
dynamics that have an arbitrarily large imaginary eigenvalue. These large
eigenvalues are fast frequencies that introduce a fast (stiff) timescale into
the dynamics. As an application, we study the phenomenon of resonant
dissipation, i.e., a motion where both particles recoil together in a drifting
circular orbit (a bound state), while the atom dissipates center-of-mass energy
only. This balancing of the stiff dynamics is established by the existence of a
quartic resonant constant that locks the dynamics to the neighborhood of the
recoiling circular orbit. The resonance condition quantizes the angular momenta
in reasonable agreement with the Bohr atom. The principal result is that the
emission lines of quantum electrodynamics (QED) agree with the prediction of
our resonance condition within one percent average deviation.Comment: 1 figure, Notice that Eq. (34) of the Phys. Rev. E paper has a typo;
it is missing the square Brackets of eq. (33), find here the correct e
Stationary probability density of stochastic search processes in global optimization
A method for the construction of approximate analytical expressions for the
stationary marginal densities of general stochastic search processes is
proposed. By the marginal densities, regions of the search space that with high
probability contain the global optima can be readily defined. The density
estimation procedure involves a controlled number of linear operations, with a
computational cost per iteration that grows linearly with problem size
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Hydrogen Fuel Cell Analysis: Lessons Learned from Stationary Power Generation Final Report
This study considered opportunities for hydrogen in stationary applications in order to make recommendations related to RD&D strategies that incorporate lessons learned and best practices from relevant national and international stationary power efforts, as well as cost and environmental modeling of pathways. The study analyzed the different strategies utilized in power generation systems and identified the different challenges and opportunities for producing and using hydrogen as an energy carrier. Specific objectives included both a synopsis/critical analysis of lessons learned from previous stationary power programs and recommendations for a strategy for hydrogen infrastructure deployment. This strategy incorporates all hydrogen pathways and a combination of distributed power generating stations, and provides an overview of stationary power markets, benefits of hydrogen-based stationary power systems, and competitive and technological challenges. The motivation for this project was to identify the lessons learned from prior stationary power programs, including the most significant obstacles, how these obstacles have been approached, outcomes of the programs, and how this information can be used by the Hydrogen, Fuel Cells & Infrastructure Technologies Program to meet program objectives primarily related to hydrogen pathway technologies (production, storage, and delivery) and implementation of fuel cell technologies for distributed stationary power. In addition, the lessons learned address environmental and safety concerns, including codes and standards, and education of key stakeholders
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