14,900 research outputs found
Field weed population models: a review of approaches and application domains
We evaluated models of weed population dynamics based on an analysis of their assumptions, biological rationale, flexibility, documentation, accessibility, demand for parameter estimation and documented validity. We arrived at general recommendations regarding which modelling approach should be applied in order to address different application domains
Tho2 dispersion-strengthened ni and ni-mo alloys produced by selective reduction
Preparation of nickel-thorium-molybdenum alloys by selective hydrogen reduction metho
Bulk and surface magnetoinductive breathers in binary metamaterials
We study theoretically the existence of bulk and surface discrete breathers
in a one-dimensional magnetic metamaterial comprised of a periodic binary array
of split-ring resonators. The two types of resonators differ in the size of
their slits and this leads to different resonant frequencies. In the framework
of the rotating-wave approximation (RWA) we construct several types of breather
excitations for both the energy-conserved and the dissipative-driven systems by
continuation of trivial breather solutions from the anticontinuous limit to
finite couplings. Numerically-exact computations that integrate the full model
equations confirm the quality of the RWA results. Moreover, it is demonstrated
that discrete breathers can spontaneously appear in the dissipative-driven
system as a results of a fundamental instability.Comment: 10 pages, 16 figure
Control of Cavity-Induced Drag Using Steady Jets
Separated shear layer oscillations in open cavities can
induce drag, noise and vibration. This issue has many
aerospace applications such as Landing gears and control
surfaces [1]. Recently, phase-cancellation [1] and offinstability
frequency excitation [2] & [3] approaches have
been incorporated in different open-loop and feedback control
systems. Despite the high control performance of these
systems, further enhancement is still possible.
In this study, steady jets, as shown in fig. 1, are forced
through 2mm, two-dimensional slots at the leading and trailing
edges of the cavity. In order to study the performance of this
novel approach, different cases will be examined, including:
jet combination (blowing from cavity leading edge, suction
from cavity leading edge and blowing-suction), jet angle
(parallel or deflected jet) and jet-to-free stream velocity
factor /.
Realizing time crystals in discrete quantum few-body systems
The exotic phenomenon of time translation symmetry breaking under periodic
driving - the time crystal - has been shown to occur in many-body systems even
in clean setups where disorder is absent. In this work, we propose the
realization of time-crystals in few-body systems, both in the context of
trapped cold atoms with strong interactions and of a circuit of superconducting
qubits. We show how these two models can be treated in a fairly similar way by
adopting an effective spin chain description, to which we apply a simple
driving protocol. We focus on the response of the magnetization in the presence
of imperfect pulses and interactions, and show how the results can be
interpreted, in the cold atomic case, in the context of experiments with
trapped bosons and fermions. Furthermore, we provide a set of realistic
parameters for the implementation of the superconducting circuit.Comment: 6 pages, 4 figure
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