Thèse : Sciences physiques : Université, Faculté des sciences de Paris : 1832. / Titre provenant de l'écran-titre.

Thesis (M.S. in Applied Physics)--Naval Postgraduate School, June 2003. / Thesis advisor(s): William B. Maier II, Richard Harkins. Includes bibliographical references (p. 45-46). Also available online.

archives@tulane.edu / Abstract Condensation of 1,8,13-tris(mercaptomethyl)triptycene and tris(bromomethyl)methane yields the in,in-cyclophane 30 in 8% yield with two inwardly directed methine groups. The X-ray analysis clearly shows that it is the in,in-isomer. The proton NMR spectrum displays an obvious coupling between the two methine hydrogens, which was proved by selectively irradiation one of the apical methine proton. The coupling constant is 2.0 Hz, which is the largest through-space coupling observed so far. Based on DFT and MP2 calculations, the hydrogen-hydrogen non-bonded contact distance is estimated to be 1.50-1.53 Å. Two in,in-cyclophanes 31 and 56, containing one or two methyl groups in their central cavities, have been synthesized, crystallized and fully characterized by ¹H and ¹³C NMR spectroscopy, MALDI-TOF mass spectrometry, IR spectroscopy, and X-ray crystallography. Cyclophane 31 is the first example of an in,in-cyclophane with a methyl group inside the cavity. The IR spectrum clearly shows that the Si-H stretch is blue-shifted from 2177 cm-1 in an acyclic model to 2269 cm-1. Based on computational studies, cyclophane 31 has a very short non-bonded H---CH3 distance of about 2.30 Å. Cyclophane 56 does not have short non-bonded contact distance, but it is the first example of a macrobicyclic compound that contains two inwardly directed methyl groups. Three cyclophanes with the formula (C28H31PS3)n, where n = 1 or 2, were isolated from the base-promoted macrocyclization of tris(2-mercaptophenyl)phosphine and tris(3-bromopropyl)methane. Spectroscopic and X-ray analysis showed them to be the in,in-isomer 32, the in,out-isomer 60, and a dimeric in,out,in,out-isomer 61. Compounds 32 and 61 display approximately C3-symmetric and Ci-symmetric structures, respectively, in the crystal, but compound 60 adopts two distinct low-symmetry conformations in the solid state. In each case, the observed structures correspond to the lowest energy conformations of their respective isomers as calculated at the B3PW91/6-31G(d) level of theory. The in,in-isomer 32 displays a close contact between the phosphine in-lone pair and the in-methine group, with through-space spin-spin coupling constants of JPH = 9 Hz and JPC = 24 Hz, the latter of which appears to be the largest reported phosphorus-carbon through-space coupling constant. Dodecaphenyltetracene (75), the largest perphenylacene yet prepared, was synthesized from known tetraphenylfuran, hexaphenylisobenzofuran, and 1,2,4,5-tetrabromo-3,6-diphenylbenzene in three steps. The X-ray structure of the deep red, highly luminescent 75 shows it to be a D2-symmetric molecule with an end-to-end twist of 97o. The central acene is encapsulated by the peripheral phenyl substituents, and as a result, the molecule is relatively unreactive and even displays reversible electrochemical oxidation and reduction. Decaphenylphenanthrene (77), the first nonlinear perphenyl polycyclic aromatic hydrocarbon to be prepared so far, has been made from tetraphenylfuran and 1,2,3,4-tetrabromo-5,6-diphenylbenzene in two steps. The X-ray structure contains two independent molecules of 77, and each of them ppssesses approximate C2 symmetry in the crystal. / 1 / yonglong xiao

La robotique souple s’inspire de la nature, de la manière dont les organismes vivants se déplacent et adaptent leur forme à leur environnement. Contrairement aux robots traditionnels, les robots souples accomplissent des tâches avec plus de flexibilité. Les matériaux souples avec lesquels ils sont construits les rendent plus sûrs pour des environnements fragiles.Cependant, le domaine de la robotique souple pose de nouveaux défis, en particulier pour la modélisation et le contrôle. Dans cette thèse, nous visons à fournir des méthodes génériques pour leur modélisation. Les méthodes sont basées sur la méthode des éléments finis pour capturer les déformations de la structure du robot, et de son environnement, quand il est déformable. Nous formulons le problème de leur cinématique inverse et dynamique inverse comme un programme d’optimisation, permettant de gérer facilement des contraintes aux actionneurs et des problèmes de singularité. Nous sommes en mesure de contrôler plusieurs types d’actionnement, tels que les actionnements par câbles, pneumatiques et hydrauliques.De plus, la plupart des applications impliquent une interaction du robot avec des obstacles. Or, la cinématique des robots souples dépend fortement des facteurs environnementaux. Nous proposons ainsi de nouvelles méthodes qui prennent en compte les contacts dans le processus d’optimisation. Enfin, nous proposons de contrôler certaines tâches de locomotion et de préhension nécessitant l’utilisation de contacts frottants (statique). Nous accordons une attention particulière à fournir des solutions avec des performances temps réel, permettant un contrôle en ligne des robots dans des environnements changeant. / Soft robotics draws its inspiration from nature, from the way living organisms move and adapt their shape to their environment. In opposition to traditional rigid robots, soft robots are built from highly compliant materials, allowing them to accomplish tasks with more flexibility. They are safer when working in fragile environment, which allows for potential use of soft robotics in the fields of manufacturing and medicine.Yet, the field of soft robotics brings new challenges, in particular for modeling and control. Within this thesis we aim at providing generic methods for soft robot modeling, without assumptions on the geometry. The methods are based on the finite element method to capture the deformations of the robot’s structure and of its environment when deformable. We formulate the problem of their inverse kinematics and dynamics as optimization programs, allowing easy handling of constraints on actuation and singularity problems. We are able to control several types of actuation, such as cable, pneumatic and hydraulic actuations.Moreover, most of the applications involve interaction of the robot with obstacles. Yet soft robots kinematics is highly dependent on environmental factors. We propose new methods that include contacts into the optimization process. These methods make an important step as we think that the knowledge of contacts in the modeling is all the more important. Finally, we propose to control some soft robots during locomotion and grasping tasks which require the use of contact with static friction. We give a particular attention to provide solutions with real-time performance, allowing online control in evolving environments.

Thèse de doctorat : Physique de la matière condensée : Metz : 2007. / Thèse soutenue sur ensemble de travaux. Bibliogr. p. 136-138.

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The non-equilibrium operation of narrow energy-gap semiconductor devices has been studied in the context of infrared detection. The fundamental mechanisms which determine medium and long wavelength infrared detector sensitivities have been reviewed, and it is proposed that the dominant factors which have necessitated the cooling of such devices in order to minimise thermal noise can be suppressed. This is contrary to previous assumptions, and is a consequence of the operation of detectors in a non-equilibrium mode where the free carrier densities are held substantially below their normal values. The prospect is offered, therefore, of the removal of the cooling requirement with less than a factor of two loss in performance. The properties of non-equilibrium minority carrier current phenomena in wide-gap semiconductors have been reviewed. The first application of these phenomena to narrow-gap devices is presented here and, specifically, the effects of minority carrier accumulation, exclusion and extraction in cadmium mercury telluride infrared detectors are demonstrated. Accumulation has been studied in swept-out extrinsic devices, where it has been shown that the responsivity can be increased by a factor of five, without loss of frequency response. Consequently, the SPRITE photoconductors have been re-designed to optimise the effects of accumulation, giving a 50% Improvement in spatial resolution. Minority carrier exclusion has been examined in intrinsic devices, where non-equilibrium carrier reductions by a factor of forty have been demonstrated at room temperature, with electric fields sufficiently low to prevent carrier heating. Increases in responsivity of up to a factor of twenty and improvements in detectivity by a factor of three have been observed, confirming that the dominant Auger generation mechanism can be suppressed. Observation of the maximum performance improvement was prevented, however, by excess surface generation and 1/f noise. Photovoltaic devices for the suppression of Auger generation through the use of extraction have been described, and the phenomena has been demonstrated at room temperature. Bipolar transistor operation has also been demonstrated for the first time in CMT. This was observed both under low temperature, extrinsic conditions and near ambient temperature where performance is maintained by extraction.

Thesis, (Ph. D.)--Oregon Graduate Institute, 2000.