441 research outputs found
Boundary controllability and source reconstruction in a viscoelastic string under external traction
Treatises on vibrations devote large space to study the dynamical behavior of
an elastic system subject to known external tractions. In fact, usually a
"system" is not an isolated body but it is part of a chain of mechanisms which
disturb the "system" for example due to the periodic rotation of shafts. This
kind of problem has been rarely studied in control theory. In the specific case
we shall study, the case of a viscoelastic string, the effect of such external
action is on the horizontal component of the traction, and so it affects the
coefficients of the corresponding wave type equation, which will be time
dependent. The usual methods used in controllability are not naturally adapted
to this case. For example at first sight it might seem that moment methods can
only be used in case of coefficients which are constant in time. Instead, we
shall see that moment methods can be extended to study controllability of a
viscoelastic string subject to external traction and in particular we shall
study a controllability problem which is encountered in the solution of the
inverse problem consisting in the identification of a distributed disturbance
source
Boundary controllability problems for the wave equation in a parallelepiped
AbstractThe wave equation in an N-dimensional parallelepiped with boundary control equal zero everywhere except of an edge of dimension N − 2 is considered. The other case which is investigated is the boundary control acting on a face of dimension N − 1 and depending on N − 1 independent variables (including t). It is proved that, in both cases, the system is not approximately controllable for any T > 0
Rational in silico design of aptamers for organophosphates based on the example of paraoxon
The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link.Poisoning by organophosphates (OPs) takes one of the leading places in the total
number of exotoxicoses. Detoxication of OPs at the first stage of the poison entering the
body could be achieved with the help of DNA- or RNA-aptamers, which are able to
bind poisons in the bloodstream. The aim of the research was to develop an approach to
rational in silico design of aptamers for OPs based on the example of paraoxon. From
the published sequence of an aptamer binding organophosphorus pesticides, its threedimensional
model has been constructed. The most probable binding site for paraoxon
was determined by molecular docking and molecular dynamics (MD) methods. Then
the nucleotides of the binding site were mutated consequently and the values of free
binding energy have been calculated using MD trajectories and MM-PBSA approach.
On the basis of the energy values, two sequences that bind paraoxon most efficiently
have been selected. The value of free binding energy of paraoxon with peripheral
anionic site of acetylcholinesterase (AChE) has been calculated as well. It has been
revealed that the aptamers found bind paraoxon more effectively than AChE. The
peculiarities of paraoxon interaction with the aptamers nucleotides have been analyzed.
The possibility of improving in silico approach for aptamer selection is discussed
Shape, Velocity, and Exact Controllability for the Wave Equation on a Graph with Cycle
Exact controllability is proven on a graph with cycle. The controls can be a
mix of controls applied at the boundary and interior vertices. The method of
proof first uses a dynamical argument to prove shape controllability and
velocity controllability, thereby solving their associated moment problems.
This enables one to solve the moment problem associated to exact
controllability. In the case of a single control, either boundary or interior,
it is shown that exact controllability fails
Exact controllability for wave equation on general quantum graphs with non-smooth controls
In this paper we study the exact controllability problem for the wave
equation on a finite metric graph with the Kirchhoff-Neumann matching
conditions. Among all vertices and edges we choose certain active vertices and
edges, and give a constructive proof that the wave equation on the graph is
exactly controllable if Neumann controllers are placed at the
active vertices and Dirichlet controllers are placed at the active
edges. The proofs for the shape and velocity controllability are purely
dynamical, while the proof for the exact controllability utilizes both
dynamical and moment method approaches. The control time for this construction
is determined by the chosen orientation and path decomposition of the graph
- …