Integral MRAC with Minimal Controller Synthesis and bounded adaptive gains: The continuous-time case

Model reference adaptive controllers designed via the Minimal Control Synthesis (MCS) approach are a viable solution to control plants affected by parameter uncertainty, unmodelled dynamics, and disturbances. Despite its effectiveness to impose the required reference dynamics, an apparent drift of the adaptive gains, which can eventually lead to closed-loop instability or alter tracking performance, may occasionally be induced by external disturbances. This problem has been recently addressed for this class of adaptive algorithms in the discrete-time case and for square-integrable perturbations by using a parameter projection strategy [1]. In this paper we tackle systematically this issue for MCS continuous-time adaptive systems with integral action by enhancing the adaptive mechanism not only with a parameter projection method, but also embedding a s-modification strategy. The former is used to preserve convergence to zero of the tracking error when the disturbance is bounded and L2, while the latter guarantees global uniform ultimate boundedness under continuous L8 disturbances. In both cases, the proposed control schemes ensure boundedness of all the closed-loop signals. The strategies are numerically validated by considering systems subject to different kinds of disturbances. In addition, an electrical power circuit is used to show the applicability of the algorithms to engineering problems requiring a precise tracking of a reference profile over a long time range despite disturbances, unmodelled dynamics, and parameter uncertainty.Postprint (author's final draft

Polyoxometalate (POM)-layered double hydroxides (LDH) composite materials: design and catalytic applications

Layered double hydroxides (LDHs) are an important large class of two-dimensional (2D) anionic lamellar materials that possess flexible modular structure, facile exchangeability of inter-lamellar guest anions and uniform distribution of metal cations in the layer. Owing to the modular accessible gallery and unique inter-lamellar chemical environment, polyoxometalates (POMs) intercalated with LDHs has shown a vast array of physical properties with applications in environment, energy, catalysis, etc. Here we describe how polyoxometalate clusters can be used as building components for the construction of systems with important catalytic properties. This review article mainly focuses on the discussion of new synthetic approaches developed recently that allow the incorporation of the element of design in the construction of a fundamentally new class of materials with pre-defined functionalities in catalytic applications. Introducing the element of design and taking control over the finally observed functionality we demonstrate the unique opportunity for engineering materials with modular properties for specific catalytic applications

Effect of environmental variables on financial performance: the case of electrical industry

Nowadays, companies at the electrical industry have to meet numerous environmental requirements which involve a large increment in their costs. However, it is considered that these investments made by organizations may affect positively to their reputation and therefore to their profits. So the aim of this paper is to analyze the influence that some Environmental variables related to the emission and resource reductions have on the Financial Performance of the electrical firms through a data panel methodology. The sample was composed by 72 electrical companies over the world, during the period 2008-2010

Shrink wrapping redox-active crystals of polyoxometalate open frameworks with organic polymers via crystal induced polymerisation

We report examples of crystal surface modification of polyoxometalate open frameworks whereby the use of pyrrole or aniline as monomers leads to the formation of the corresponding polymers via an oxidative polymerization process initiated by the redox active POM scaffolds. Guest-exchange experiments demonstrate that the polymers can finely tune the guest exchange rate and their structural integrity is retained after the surface modifications. In addition, the formation of polyoxometalate-based self-fabricating tubes by the dissolution of Keggin-based network crystals were also modulated by the polymers, allowing a new type of hybrid inorganic polymer with an organic coating to be fabricated

Sustainability drivers, barriers and outcomes: Evidence from European High Performance Manufacturing Industries

Implementing sustainability practices has become a requirement to be able to operate in several markets since the legal requirements are increasing and society (as well as customers) values sustainability behaviors more. The aims of this paper are (1) to analyze the impact that drivers and barriers have on Environmental practices implemented in the high performance manufacturing industries, (2) to identify the relevant drivers and barriers for these environmental practices, and finally, (3) to study the influence that Environmental practices have on companies´ Financial Performance. To carry out our research, we shall consider a European database of companies involved in the High Performance Manufacturing project. Partial Least Squares (PLS) will be used to test our hypotheses

Self-assembly in polyoxometalate and metal coordination-based systems: synthetic approaches and developments

Utilizing new experimental approaches and gradual understanding of the underlying chemical processes has led to advances in the self-assembly of inorganic and metal–organic compounds at a very fast pace over the last decades. Exploitation of unveiled information originating from initial experimental observations has sparked the development of new families of compounds with unique structural characteristics and functionalities. The main source of inspiration for numerous research groups originated from the implementation of the design element along with the discovery of new chemical components which can self-assemble into complex structures with wide range of sizes, topologies and functionalities. Not only do self-assembled inorganic and metal–organic chemical systems belong to families of compounds with configurable structures, but also have a vast array of physical properties which reflect the chemical information stored in the various “modular” molecular subunits. The purpose of this short review article is not the exhaustive discussion of the broad field of inorganic and metal–organic chemical systems, but the discussion of some representative examples from each category which demonstrate the implementation of new synthetic approaches and design principles

Didactique interdisciplinaire musique-langue: Pour une appropriation de la sphère oro-audiale

L'écrit en tant que support éducatif précoce et généralisé prouve son efficacité dans l'établissement chez l'apprenant d'un statut de lecteur/scripteur. Cette position ne se limite pas à une capacité : savoir écrire, mais influence largement les caractéristiques d'abstraction et de conceptualisation de l'oral dans le domaine d'apprentissage. Faire intervenir la question de " bonne prononciation " dans les cours de langue étrangère revient à dépasser les clivages inter- et intra-personnels afin de réfléchir sur la capacité à conceptualiser l'objet oral. Les méthodes communicatives pures dans le domaine de la phonétique " corrective " ont pour effet de " sollicit[er] chez les apprenants, dès les premières heures de cours, une forte implication affective souvent disproportionnée par rapport à leurs modestes ressources d'expression "1. Musique instrumentale et langage sont intrinsèquement liés de par leurs propriétés acoustiques. Ces deux réalisations sonores se voient traitées de manière différente sur le plan social: la position humaniste met en avant la capacité communicative et sociale du langage en opposition à celle affective de la musique. Le rapport à l'écrit de l'individu crée en quelque sorte une représentation mentale hybride du langage entre objet visuel et objet sonore. L'enseignant peut jouer sur cette double représentation lorsque R. Dubé affirme que: "le meilleur moyen d'apprendre à écrire un mot n'est pas de l'épeler cent fois de suite, c'est de l'emmagasiner dans son esprit comme une image ". Il est dès lors important de réfléchir sur les moyens didactiques qui peuvent permettre à l'enseignant de langue étrangère, notamment dans la prononciation et grâce à la musique instrumentale, à venir se poser comme médiateur entre des structures écrites peu spontanées et un système oral affectivement déstabilisant. La recherche portera sur les liens qui unissent musique et langue sur les plans segmentaux, cognitifs et didactiques afin de voir sous le prisme de la didactique musicale, quelles sont les utilisations possible de la musique instrumentale en cours de phonétique " corrective ". De plus, à travers la notion de " bonne " prononciation et des construits épistémologiques que cela implique, nous verrons comment la position d'interprète (en opposition à exécutant en musique) peut être transférée à celle d'orateur en L2. De ce constat, il sera donc envisagé de théoriser sur la notion de sphère oro-audiale dans le but d'induire une approche ne visant pas à imiter la prononciation d'un locuteur " natif " mais bien à amener l'apprenant à se sentir bien dans cette nouvelle langue. En ce sens, il nous faudra rappeler les avancées neurocognitives entre musique et langage en s'appuyant notamment sur les recherches de A. Patel, B. Tillmann, L. Hoch, D. Levitin, H. Gardner, etc... A travers les principes généraux de la méthode verbo-tonale, nous verrons en quoi l'utilisation de la musique instrumentale en classe, et plus particulièrement en classe de phonétique corrective, permet de développer la question de l'orateur comme exécutant ou interprète via l'ineffable4 et les questions d'intuition, confiance, bien-être. La notion de sphère oro-audiale sera à la base de la réflexion visant à considérer l'univers conceptuel de chacun dans l'appropriation du monde oral pour l'apprentissage des langues. Les problèmes d'abstraction des concepts5 et de la notion de crible6 seront plus particulièrement traités. Enfin, il pourra être montré une théorisation possible sous forme d'activité phonétique mêlant unités musicales et langagière en fonction de l'avancée des données empiriques. Cette dernière met en relation intervalles de notes (do, ré, mi, fa, etc...) et les intervalles articulatoires des continua phonémiques du français ( /a/, /ε /, /e/, /i/, etc...) en faisant écho au " bonhomme sonore "7 de Guimbretière. L'intérêt reposant sur une appropriation du trapèze vocalique pour une imprégnation de la musicalité du français, mais aussi travailler sur l'accès mémoriel des espaces sonores des langues

Analysis of the dynamics of an active control of the surface potential in metal oxide gas sensors

Postprint (author's final draft

Modular polyoxometalate-layered double hydroxide composites as efficient oxidative catalysts

The exploitation of intercalation techniques in the field of two-dimensional layered materials offers unique opportunities for controlling chemical reactions in confined spaces and developing nanocomposites with desired functionality. In this paper, we demonstrate the exploitation of the novel and facile ‘one-pot’ anion-exchange method for the functionalization of layered double hydroxides (LDHs). As a proof of concept, we demonstrate the intercalation of a series of polyoxometalate (POM) clusters, Na3[PW12O40]•15H2O (Na3PW12), K6[P2W18O62]•14H2O (K6P2W18), and Na9LaW10O36•32H2O (Na9LaW10) into tris(hydroxymethyl)amino-methane (Tris) modified layered double hydroxides (LDHs) under ambient conditions without the necessity of degassing CO2. Investigation of the resultant intercalated materials of Tris-LDHs-PW12 (1), Tris-LDH-P2W18 (2), and Tris-LDH-LaW10 (3) for the degradation of methylene blue (MB), rhodamine B (RB) and crystal violet (CV) has been carried out, where Tris-LDH-PW12 reveals the best performance in the presence of H2O2. Additionally, degradation of a mixture of RB, MB and CV by Tris-LDH-PW12 follows the order of CV > MB > RB, which is directly related to the designed accessible area of the interlayer space. Also, the composite can be readily recycled and reused at least ten cycles without measurable decrease of activity