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We consider the problem of stabilizing a class of systems formed by a set of decoupled subsystems (nodes) interconnected through a set of controllers (arcs). Controllers are network-decentralized, i.e., they use information exclusively from the nodes they interconnect. This condition requires a block-structured feedback matrix, having the same structure as the transpose of the overall input matrix
A novel approach to the problem of inverse kinematics for redundant manipulators has been recently introduced: by considering the joints as point masses in a fictitious gravity field, and by adding proper constraints to take into account the length of the links, the kinematic inversion may be cast as a convex programming problem. Such a problem can be solved in an efficient way and may be easily m
This paper deals with set invariance for time delay systems. The first goal of the paper is to review the known necessary or sufficient conditions for the existence of invariant sets with respect to dynamical systems described by discrete-time delay difference equations (dDDEs). Secondly, we address the construction of invariant sets in the original state space (also called D-invariant sets) by ex
The paper analyses some continuous-time dynamic models that describe the evolution of social systems characterized by the possibility of changing the alliances among the parties involved or damaging one's competitors. At any time each participant, either an individual or a coalition, can decide to form or terminate a bond, or to start or stop damaging an opponent (i.e., to switch from a network co
In this chapter, a control design approach based on linear parametervarying (LPV) systems, which can be exploited to solve several problems typically encountered in control engineering, is presented. By means of recent techniques based on Youla–Kucera parametrization, it is shown how it is possible not only to design and optimize stabilizing controllers, but also to exploit the structure of the Yo
Most of the existing techniques for palmprint recognition are based on metrics that evaluate the distance between a pair of features. These metrics are typically based on static functions. In this paper we propose a new technique for palmprint recognition based on a dynamical system approach, focusing on preliminary experimental results. The essential idea is that the procedure iteratively elimina
Due to the intrinsic uncertainty and variability affecting biochemical reaction networks, it is fundamental to assess their structural stability, i.e., to establish if all the networks having a given structure are stable independent of specific parameter values. For basic motifs in biochemical networks, we show that stability cannot be structurally proved by quadratic Lyapunov functions. However,
We design a new negative feedback molecular oscillator and study its properties analytically and numerically. This oscillator is composed of two synthetic genes interconnected through their RNA outputs. Regulation of the genes activity is achieved by controlling the activity of the enzymes rather than the activity of the promoters. We show that a simple model of this system has the potential to os
We propose a negative feedback architecture that regulates activity of artificial genes, or "genelets", to meet their output downstream demand, achieving robustness with respect to uncertain open-loop output production rates. In particular, we consider the case where the outputs of two genelets interact to form a single assembled product. We show with analysis and experiments that negative autoreg
Molecular systems are uncertain: The variability of reaction parameters and the presence of unknown interactions can weaken the predictive capacity of solid mathematical models. However, strong conclusions on the admissible dynamic behaviors of a model can often be achieved without detailed knowledge of its specific parameters. In systems with a sign-definite Jacobian, for instance, cycle-based cr
We consider a traffic control problem defined on a network graph, whose nodes represent buffers and whose arcs represent flow channels. We consider network models with a peculiar aspect: each element of the flow arriving at each node must be redirected towards a precise other node of the network, hence each buffer is naturally split in several queues, characterized according to statistics about th
We consider the problem of assessing structural stability of biochemical reaction networks with monotone reaction rates, namely of establishing if all the networks with a certain structure are stable regardless of specific parameter values. We investigate stability by absorbing the network equations in a linear differential inclusion and seeking for a polyhedral Lyapunov function proper to the con
This paper focuses on the regulation of RNA production for in vitro synthetic gene networks. We consider the problem of matching the production rate of several RNA species concurrently transcribed to form RNA complexes. We design regulatory feedback loops based on two schemes: negative auto-regulation (which can minimize the potentially harmful amount of molecules not used to form products) and cr
In this paper we consider a set of dynamically decoupled systems interconnected by control agents. We can visualize this architecture as a graph where subsystems are associated to nodes and control agents are associated to arcs. The interconnection between subsystems is determined by their input matrix. The decisions of each control agent can directly affect only the nodes connected by the corresp
A property for a class of systems is said to be structural if it is met by any system in the class regardless of the adopted parameters. In this paper we investigate the structural nature of oscillatory behaviors, adaptation and monotonicity in a class of sign-invariant systems, capturing a wide variety of biological models. We employ standard robustness analysis tools, suitably tailored to the ca
This paper addresses set invariance properties for linear time-delay systems. More precisely, the first goal of the article is to review known necessary and/or sufficient conditions for the existence of invariant sets with respect to dynamical systems described by linear discrete time-delay difference equations (dDDEs). Secondly, we address the construction of invariant sets in the original state
Seeds of clover and lucerne were sown in equal proportions in mixtures at high densities. Thinning started earlier in clover but in both species, after thinning commenced, it proceeded at the same rate. Both species underwent collective self-thinning in accordance with the -3/2 power law but although the slopes for the species were the same the intercepts differed strongly. Plants of lucerne of a
To evaluate hypotheses explaining intraspecific variation in migratory behavior in partial migrants, a local population of Blue Tits (Parus caeruleus) was studied in southern Sweden. Birds born in the study area and recaptured there in winter were compared with birds recaptured at a nearby bird station where a large number of migrant Blue Tits were passing. By comparing sex ratios among migrants a
Male pied flycatches Ficedula hypoleuca regularly feed their mates during incubation. By experimentally supplying some females with extra food we studied how the female's nutritional state affected her incubation schedule and the rate at which her mate fed her. Females that received extra food spent more time on the nest and shorter periods away from it, compared with control females. This suggest
