1,066 research outputs found
Particle creation by moving spherical shell in the dynamical Casimir effect
The creation of massless scalar particles from the quantum vacuum by
spherical shell with time varying radius is studied. In the general case of
motion the equations are derived for the instantaneous basis expansion
coefficients. The examples are considered when the mean number of particles can
be explicitly evaluated in the adiabatic approximation.Comment: 9 pages, LaTeX, no figures, typos corrected, discussion added.
Journal-ref adde
Quantum field between moving mirrors: A three dimensional example
The scalar quantum field uniformly moving plates in three dimensional space is studied. Field equations for Dirichlet boundary conditions are solved exactly. Comparison of the resulting wavefunctions with their instantaneous static counterpart is performed via Bogolubov coefficients. Unlike the one dimensional problem, 'particle' creation as well as squeezing may occur. The time dependent Casimir energy is also evaluated
Rotational dynamics induced by low energy binary collisions of quantum droplets
A theoretical analysis of the rotational dynamics induced by off axis binary
collisions of quantum droplets constituted by ultracold atoms is reported. We
focus on quantum droplets formed by degenerate dilute Bose gases made up from
binary mixtures of alkaline atoms under feasible experimental conditions. The
stability of the ground state is known to be longer for the chosen
heteronuclear gases than for the homonuclear ones. In both cases, we find out
that the dynamics seems to privilege a high similarity of the density of each
atomic species. However, the evolution of the phase of the corresponding order
parameter differs significantly for heteronuclear admixtures. We evaluate the
fidelity as a figure of merit for the overlap between the order parameters of
each atomic species. Dynamical evidence of the differences between the phase of
the order parameters are predicted to manifest in their corresponding linear
and angular momenta. We numerically verify that the total angular and linear
momenta are conserved both during the collision. Some direct correlations
between the Weber number and the impact parameter with the distribution of the
dynamical variables are established.Comment: 12 pages, 6 figure
Finding robust investments for the Dutch gas distribution infrastructure in 2050 by a scenario study
In the changing Dutch energy market, the ageing gas distribution grid needs investments. There is,
however, a large uncertainty regarding certain aspects that affect the future role of this gas distribution grid, such as the eventual share of biomethane in the gas mix, whether power-to-gas will take-off and the expected lifetime of the grid. Hence, it is currently unclear what investments need to be made for the gas distribution infrastructure in order to cope with future changes. To find out how the future may unfold for the Dutch gas distribution infrastructure in 2050, four scenarios have been developed. Two key forces – a key force is a factor that has a large impact on the gas distribution grid but great uncertainty exists regarding its outcome – were chosen, namely “perceived energy resource scarcity” and “willingness and ability to reduce greenhouse gas emissions”. Each scenario sketches the future Dutch gas infrastructure by defining, among others, the extent to which biomass will be used to produce biomethane, whether fossil fuel is allowed to be burned locally, and what types of gas will flow through the gas grid. With these scenarios at our disposal, in the next research step, we will establish the impact of the scenarios on the gas distribution grid – i.e. what the layout will be and the corresponding costs – and the accompanying biomethane infrastructure. For this, 3 typical locations were chosen: a rural region, an urban region, and an intermediate region. Through a multi-objective optimization – with maximizing net present value, maximizing biomethane production, and maximizing CO2 emission reduction as objectives – the possible layout of the gas distribution grid and the biomethane infrastructure will be determined for each region. The study’s aim is to find similarities in investments among the different layouts, to come to robust investments for the gas distribution infrastructure
Particle creation in an oscillating spherical cavity
We study the creation of massless scalar particles from the quantum vacuum
due to the dynamical Casimir effect by spherical shell with oscillating radius.
In the case of a small amplitude of the oscillation, to solve the infinite set
of coupled differential equations for the instantaneous basis expansion
coefficients we use the method based on the time-dependent perturbation theory
of the quantum mechanics. To the first order of the amplitude we derive the
expressions for the number of the created particles for both parametric
resonance and non-resonance cases.Comment: 8 pages, LaTeX, no figure
Supporting industrial equipment development through a set of design-for-maintenance guidelines
This paper presents a leaflet with design-for-maintenance guidelines. It aims at supporting developers of industrial equipment in their design-for-maintenance practices. The use of this leaflet should lead to increased attention for design-for-maintenance aspects and to improve idea generation. The way of presenting the guidelines to the user should ensure that the support will be adopted in practice. The feedback that we have received from industrial partners indicates that the support is useful in practice. A thorough evaluation study has been planned in order to confirm this
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