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991.
Bruno Romeira Ricardo Avó Julien Javaloyes Salvador Balle Charles N. Ironside José M. L. Figueiredo 《Optical and Quantum Electronics》2014,46(10):1391-1396
We investigate the dynamics of optoelectronic oscillator (OEO) systems based on resonant tunneling diode photodetector (RTD-PD) and laser diode hybrid integrated circuits. We demonstrate that RTD-based OEOs can be noise-activated in either monostable or bistable operating conditions, providing a rich variety of signal outputs—spiking, square pulses, bursting—and behaviours—stochastic and coherence resonances—that are similar to that of biological systems such as neurons. The potential for fully monolithic integration of our OEO confers them a great potential in novel neuromorphic optoelectronic circuits for signal processing tasks including re-timing and re-shaping of pulsed signals exploiting either the monostable or the bistable operating conditions. 相似文献
992.
Christelle Der Loughian Loïc Tadrist Jean-Marc Allain Julien Diener Bruno Moulia Emmanuel de Langre 《Comptes Rendus Mecanique》2014,342(1):1-7
Model plants are extensively used in biological studies, and their mechanical behaviour needs to be better understood, in relation to studies in mechanoperception for instance. We present here the first approach to derive experimentally the modal parameters of two of these plants, Arabidopsis thaliana and Populus tremula × alba. A classical sinusoidal sweep excitation is used, with a measurement of displacements based on LKT optical flow tracking, followed by a bi-orthogonal decomposition (BOD). This allows us to estimate several modal frequencies for each plant, as well as the corresponding spatial localizations of deformation. Analyzing the modal frequencies, we show that global and local modes correspond to distinct ranges of frequencies and depend differently on plant size. Possible phenotyping applications are then discussed. 相似文献
993.
Matheus Palhares Viana Bruno A.N. Traven?olo Esther Tanck Luciano da Fontoura Costa 《Physica A》2010,389(8):1771-1778
The properties of complex networks are highly influenced by border effects frequently found as a consequence of the finite nature of real-world networks as well as network sampling. Therefore, it becomes critical to devise effective means for sound estimation of network topological and dynamical properties while avoiding these types of artifacts. In the current work, an algorithm for minimization of border effects is proposed and discussed, and its potential is illustrated with respect to two real-world networks, namely bone canals and air transportation. 相似文献
994.
Jean-Paul Douliez Bérénice Houinsou-Houssou Anne-Laure Fameau Bruno Novales Cédric Gaillard 《Journal of colloid and interface science》2010,341(2):386-389
A mixture between 1% sodium myristate and guanidine hydrochloride at a molar ratio of 1 in water forms a gel of membranes below a phase transition of ca. 21 °C and a viscous limpid and isotropic solution above. As observed by both TEM and AFM, we report the formation of interconnected superstructures in that latter phase. Those assemblies exhibit a size of ca. 4–40 nm width and several tens of μm length with unexpected disconnections and re-connections between them having the appearance of an anastomosis-like superstructure. 相似文献
995.
The component-mode synthesis method is usually adopted in order to reduce the number of degrees-of-freedom of structures composed of two or more substructures without loosing the main physical characteristics of the whole structure. Many approaches of this method have been proposed in the literature. These approaches differ from each other for the boundary conditions which are imposed at the interface of the two substructures. In this paper four variants of interface boundary conditions are examined. For each set of conditions a suitable coordinate transformation, compatible with the conditions at the boundary degrees-of-freedom between the two substructures, is presented. Moreover, in the numerical applications a comparison between the four component-mode synthesis variants here proposed with respect to the same variants proposed in the literature is presented. The better accuracy of the proposed approach is shown. 相似文献
996.
Paula V. Messina Olga Pieroni Bruno Vuano Juan Manuel Ruso Gerardo Prieto Félix Sarmiento 《Journal of inclusion phenomena and macrocyclic chemistry》2010,67(3-4):343-352
The behavior of insoluble calix[n]arene and resorcinol[n]arene derivatives monolayers were studied through the use of a constant surface Langmuir balance based on Axisymmetric Drop Shape Analysis (ADSA). In each case, a stable monolayer was obtained and different transitions (induced for lateral compression) could be identified. Thermodynamic parameters were computed through two dimensional Clausius–Clayperon equations and used to valuate the monolayer stability. A noticeable reduction of thermodynamic parameters occurred at highly tested temperatures (328 and 338 K) for those compounds that had hydrocarbon tails or benzene rings attached to one side of macrocyclic rim. Such fact was related to a monolayer rearrangement where the macrocyclic ring changed from a parallel to a perpendicular orientation. In this orientation the hydrophobic interactions between hydrocarbon chains and benzene rings were maximized. At highly temperature, where vigorous molecular motion existed, those interactions were superior to the stabilization effect through hydrogen bond. 相似文献
997.
In the present paper the authors propose a portable and low-cost speckle interferometer for evaluating 3D deformation fields. The interferometer was designed and realized with the aim of carrying out measurements on small areas, hence it can be used to approach problems characterized by displacement field with highly localized gradients, such as the strain relief occurring in residual stress evaluation or the displacements which arise around notches or crack tips. The costs of the experimental equipment were reduced by employing laser diodes as light sources, a PZT actuator designed and calibrated by the authors and a control electronics realized on purpose. Moreover the configuration which was adopted allows further saving on optical components. The experimental results reported at the end of the paper, and obtained by a specimen subjected to 3D rigid body motions, show a high repeatability and accuracy. Furthermore the experimental results have shown that the geometry of the optical setup implies the variation of the sensitivity vectors on the inspected area, but this effect can be evaluated (analytically and/or experimentally) and taken into account in order to increase the accuracy of the measurements. 相似文献
998.
Maria Inês Bruno Tavares 《Polymer Testing》2000,19(8):899-904
Analysis of the dynamic behaviour of two highly crystalline polymers, polyethylene (HDPE) and polypropylene (iPP) was carried out by solution and solid state nuclear magnetic resonance (NMR) to obtain the response of the behaviour of both polymers with respect to the molecular chain dynamics, the chain ordination and the molecular packing. The proton spin-lattice relaxation time in the rotating frame (T1Hρ) showed that HDPE is more rigid than iPP, because the chain orientation and the molecular packing are different. T1Hρ parameter also depends on the molecular chain dynamics, as a result of the different sequence distribution in the domains 相似文献
999.
1000.
The sulfone 2 , and the sulfoxides (S)‐ 3 and (R)‐ 3 were obtained by oxidation of the thiomethylene‐linked A*[s ]U dinucleoside 1 . Conformational analysis and association studies of 2 , (S)‐ 3 , and (R)‐ 3 reveal a strong influence of the configuration on the conformation of the linking unit and on the self‐association of the dinucleosides. 相似文献