Nonsmooth stabilizability and feedback linearization of discrete-time nonlinear systems

We consider the problem of stabilizing a discrete-time nonlinear system using a feedback which is not necessarily smooth. A sufficient condition for global dynamical stabilizability of single-input triangular systems is given. We obtain conditions expressed in terms of distributions for the nonsmooth feedback triangularization and linearization of discrete-time systems. Relations between stabilization and linearization of discrete-time systems are given

Control design for an overactuated wheeled mobile robot

In order to simulate road vehicles in a hardware-in-the-loop test setup, TNO has developed a wheeled mobile robot with independently driven and steered wheels. This robot is overactuated, i.e. the number of actuators exceeds the number of spatial degrees of freedom to be controlled. A position controller based on feedback linearization is presented. This controller takes the overactuatedness into account by using the so-called multicycle approach, which essentially regards the robot as a combination of independent unicycles. As a result, the robot is position controlled while the redundant actuators are used to compensate for weight transfer during acceleration and cornering

Collective Almost Synchronization in Complex Networks

This work introduces the phenomenon of Collective Almost Synchronization (CAS), which describes a universal way of how patterns can appear in complex networks even for small coupling strengths. The CAS phenomenon appears due to the existence of an approximately constant local mean field and is characterized by having nodes with trajectories evolving around periodic stable orbits. Common notion based on statistical knowledge would lead one to interpret the appearance of a local constant mean field as a consequence of the fact that the behavior of each node is not correlated to the behaviors of the others. Contrary to this common notion, we show that various well known weaker forms of synchronization (almost, time-lag, phase synchronization, and generalized synchronization) appear as a result of the onset of an almost constant local mean field. If the memory is formed in a brain by minimising the coupling strength among neurons and maximising the number of possible patterns, then the CAS phenomenon is a plausible explanation for it.Comment: 3 figure

Onset of chaotic advection in open flows

Non peer reviewedPublisher PD

Controlling surface morphologies by time-delayed feedback

We propose a new method to control the roughness of a growing surface, via a time-delayed feedback scheme. As an illustration, we apply this method to the Kardar-Parisi-Zhang equation in 1+1 dimensions and show that the effective growth exponent of the surface width can be stabilized at any desired value in the interval [0.25,0.33], for a significant length of time. The method is quite general and can be applied to a wide range of growth phenomena. A possible experimental realization is suggested.Comment: 4 pages, 3 figure

In-phase and anti-phase synchronization of oscillators with Huygens' coupling

In this experimental study, the synchronized motion observed in pairs of nonlinear oscillators coupled through a suspended rigid bar, is analyzed. In particular, the dynamics of two mass-spring-damper oscillators and the dynamics of two van der Pol oscillators are considered. It is shown that in both cases, the oscillators may exhibit in-phase and anti-phase synchronization. The experiments are executed in an experimental setup, consisting of two mass-spring-damperoscillators coupled through a suspended rigid bar. A relation between the obtained results and Huygens’ experiment of pendulum clocks is emphasized

Direct Visualization of Single Nuclear Pore Complex Proteins Using Genetically-Encoded Probes for DNA-PAINT

The nuclear pore complex (NPC) is one of the largest and most complex protein assemblies in the cell and, among other functions, serves as the gatekeeper of nucleocytoplasmic transport. Unraveling its molecular architecture and functioning has been an active research topic for decades with recent cryogenic electron microscopy and super-resolution studies advancing our understanding of the architecture of the NPC complex. However, the specific and direct visualization of single copies of NPC proteins is thus far elusive. Herein, we combine genetically-encoded self-labeling enzymes such as SNAP-tag and HaloTag with DNA-PAINT microscopy. We resolve single copies of nucleoporins in the human Y-complex in three dimensions with a precision of circa 3 nm, enabling studies of multicomponent complexes on the level of single proteins in cells using optical fluorescence microscopy