3,752 research outputs found
Participatory plant breeding in Denmark
Plant breeding gets more and more concentrated on a couple of multinational companies, and financing plant breeding via the traditional royalty founded certification system exclusive for the specific needs in organic farming is not profitable in most field crops. The seed certification system only allows pure line varieties, and the royalty funded breeding system tend to focus on monogenic resistance with s short durability on the marked. To develop new plant genetic material for organic farmers with durable stability and resistance, the Danish Organic Farmers Association has initiated a participatory plant breeding program with the aim to develop varieties and diverse populations for the organic farmers. The project is based within the advisory service in the organisation in cooperation with plant breeding research projects. In this way, it is the hope to overcome the economic and legal barrier for implementation of crop diversity and targeted selection for the different needs in the diverse organic sector
Four results on phi^4 oscillons in D+1 dimensions
We present four results for oscillons in classical phi^4 theory in D+1
space-time dimensions, based on numerical simulations. These include the
oscillon lifetime and the dependence on D; evidence for the uniqueness of the
oscillon; evidence for the existence of oscillons beyond D=7; and a brief study
of the spectrum of the radiation emitted from the oscillons before, during and
after its ultimate demise.Comment: 12 pages, 16 figure
Distributed Robustness Analysis of Interconnected Uncertain Systems Using Chordal Decomposition
Large-scale interconnected uncertain systems commonly have large state and
uncertainty dimensions. Aside from the heavy computational cost of solving
centralized robust stability analysis techniques, privacy requirements in the
network can also introduce further issues. In this paper, we utilize IQC
analysis for analyzing large-scale interconnected uncertain systems and we
evade these issues by describing a decomposition scheme that is based on the
interconnection structure of the system. This scheme is based on the so-called
chordal decomposition and does not add any conservativeness to the analysis
approach. The decomposed problem can be solved using distributed computational
algorithms without the need for a centralized computational unit. We further
discuss the merits of the proposed analysis approach using a numerical
experiment.Comment: 3 figures. Submitted to the 19th IFAC world congres
Distributed Robust Stability Analysis of Interconnected Uncertain Systems
This paper considers robust stability analysis of a large network of
interconnected uncertain systems. To avoid analyzing the entire network as a
single large, lumped system, we model the network interconnections with
integral quadratic constraints. This approach yields a sparse linear matrix
inequality which can be decomposed into a set of smaller, coupled linear matrix
inequalities. This allows us to solve the analysis problem efficiently and in a
distributed manner. We also show that the decomposed problem is equivalent to
the original robustness analysis problem, and hence our method does not
introduce additional conservativeness.Comment: This paper has been accepted for presentation at the 51st IEEE
Conference on Decision and Control, Maui, Hawaii, 201
Robust Stability Analysis of Sparsely Interconnected Uncertain Systems
In this paper, we consider robust stability analysis of large-scale sparsely
interconnected uncertain systems. By modeling the interconnections among the
subsystems with integral quadratic constraints, we show that robust stability
analysis of such systems can be performed by solving a set of sparse linear
matrix inequalities. We also show that a sparse formulation of the analysis
problem is equivalent to the classical formulation of the robustness analysis
problem and hence does not introduce any additional conservativeness. The
sparse formulation of the analysis problem allows us to apply methods that rely
on efficient sparse factorization techniques, and our numerical results
illustrate the effectiveness of this approach compared to methods that are
based on the standard formulation of the analysis problem.Comment: Provisionally accepted to appear in IEEE Transactions on Automatic
Contro
Surface tension and the origin of the circular hydraulic jump in a thin liquid film
It was recently claimed by Bhagat et al. (J. Fluid Mech. vol. 851 (2018), R5)
that the scientific literature on the circular hydraulic jump in a thin liquid
film is flawed by improper treatment and severe underestimation of the
influence of surface tension. Bhagat {\em et al.} use an energy equation with a
new surface energy term that is introduced without reference, and they conclude
that the location of the hydraulic jump is determined by surface tension alone.
We show that this approach is incorrect and derive a corrected energy equation.
Proper treatment of surface tension in thin film flows is of general interest
beyond hydraulic jumps, and we show that the effect of surface tension is fully
contained in the Laplace pressure due to the curvature of the surface.
Following the same approach as Bhagat et al., i.e., keeping only the first
derivative of the surface velocity, the influence of surface tension is, for
thin films, much smaller than claimed by them. We further describe the
influence of viscosity in thin film flows, and we conclude by discussing the
distinction between time-dependent and stationary hydraulic jumps.Comment: 9 pages, 1 figur
Distributed Interior-point Method for Loosely Coupled Problems
In this paper, we put forth distributed algorithms for solving loosely
coupled unconstrained and constrained optimization problems. Such problems are
usually solved using algorithms that are based on a combination of
decomposition and first order methods. These algorithms are commonly very slow
and require many iterations to converge. In order to alleviate this issue, we
propose algorithms that combine the Newton and interior-point methods with
proximal splitting methods for solving such problems. Particularly, the
algorithm for solving unconstrained loosely coupled problems, is based on
Newton's method and utilizes proximal splitting to distribute the computations
for calculating the Newton step at each iteration. A combination of this
algorithm and the interior-point method is then used to introduce a distributed
algorithm for solving constrained loosely coupled problems. We also provide
guidelines on how to implement the proposed methods efficiently and briefly
discuss the properties of the resulting solutions.Comment: Submitted to the 19th IFAC World Congress 201
Inverse magnetic catalysis and regularization in the quark-meson model
Motivated by recent work on inverse magnetic catalysis at finite temperature,
we study the quark-meson model using both dimensional regularization and a
sharp cutoff. We calculate the critical temperature for the chiral transition
as a function of the Yukawa coupling in the mean-field approximation varying
the renormalization scale and the value of the ultraviolet cutoff. We show that
the results depend sensitively on how one treats the fermionic vacuum
fluctuations in the model and in particular on the regulator used. Finally, we
explore a -dependent transition temperature for the Polyakov loop potential
using the functional renormalization group. These results show that
even arbitrary freedom in the function does not allow for a decreasing
chiral transition temperature as a function of . This is in agreement with
previous mean-field calculations.Comment: 13 pages, 5 figure
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