Interwall conductance in double-walled armchair carbon nanotubes

The dependence of the interwall conductance on distance between walls and relative positions of walls are calculated at the low voltage by Bardeen method for (n,n)@(2n,2n) double-walled carbon nanotubes (DWCNTs) with n=5,6,…,10. The calculations show that interwall conductance does not depend on temperature (for T?500 K) and current-voltage characteristic is linear. The conductance decreases by 6 orders of magnitude when the interwall distance is doubled. Thus, depending on the interwall distance, DWCNTs can be used as temperature stable nanoresistors or nanocapacitors.     

Large displacement analysis of shear deformable composite beams with interlayer slips

This paper presents a novel geometric non-linear finite element formulation for the analysis of shear deformable two-layer beams with interlayer slips. We adopt the co-rotational approach where the motion of the element is decomposed into two parts: a rigid body motion which defines a local coordinate system and a small deformational motion of the element relative to this local coordinate system. The main advantage of this approach is that the transformation matrices relating local and global quantities are independent to the choice of the geometrical linear local element. The effect of transverse shear deformation of the layers is taken into account by assuming that each layer behaves as a Timoshenko beam element. The layers are assumed to be continuously connected and partial interaction is considered by considering a continuous relationship between the interface shear flow and the corresponding slip. In order to avoid curvature and shear locking phenomena, the local linear element is formulated using “exact” displacement shape functions derived from the closed-form solution of the governing equations of a two-layer beam element. Finally, three numerical applications are presented in order to assess the performance of the proposed formulation.     

Exact buckling solution for two-layer Timoshenko beams with interlayer slip

This paper deals with the buckling behavior of two-layer shear-deformable beams with partial interaction. The Timoshenko kinematic hypotheses are considered for both layers and the shear connection (no uplift is permitted) is represented by a continuous relationship between the interface shear flow and the corresponding slip. A set of differential equations is obtained from a general 3D bifurcation analysis, using the above assumptions. Original closed-form analytical solutions of the buckling load and mode of the composite beam under axial compression are derived for various boundary conditions. The new expressions of the critical loads are shown to be consistent with the ones corresponding to the Euler–Bernoulli beam theory, when transverse shear stiffnesses go to infinity. The proposed analytical formulae are validated using 2D finite element computations. Parametric analyses are performed, especially including the limiting cases of perfect bond and no bond. The effect of shear flexibility is particularly emphasized.     

A single-camera technique for simultaneous measurement of large solid particles transported in rapid shallow channel flows

This paper describes a measurement technique that was successfully applied in a study of bed load transport of large spherical solid particles in a shallow and supercritical flow (Fr?=?2.59–3.17) down a steep slope. The experimental condition was characterized by the relatively large solid particle size compared to the flow depth (d _p /h?=?0.23–0.35), and compared to the tracer diameter (d _p /d _t ?≈?130). The technique incorporated particle image velocimetry and particle tracking velocimetry (PTV) to simultaneously measure the characteristics of the two phases. In order to detect true solid particles and to distinguish them from each other and the unwanted objects, a particle characterization (PCR) algorithm based on Hough transform was employed. The output from the PCR process was utilized for PTV, as well as to generate the corresponding tracer images for special needs. Validation tests have confirmed the pixel accuracy and high reliability of the combined technique. Experimental results obtained with the developed technique include flow velocities, particle velocities, and concentration. The analysis has shown that the particle concentration profile followed an exponential relationship of the form similar to that of Rouse’s profiles, despite the large d _p /h ratio. It also revealed the effect of phase interaction, as a low loading rate of light particles on the order of O(10^?3) could yield a noticeable slowdown in the streamwise fluid velocity.     

Pullback Attractors for Stochastic Young Differential Delay Equations

We study the asymptotic dynamics of stochastic Young differential delay equations under the regular assumptions on Lipschitz continuity of the coefficient functions. Our main results show that, if there is a linear part in the drift term which has no delay factor and has eigenvalues of negative real parts, then the generated random dynamical system possesses a random pullback attractor provided that the Lipschitz coefficients of the remaining parts are small.

     

Zur Kenntnis der μ-Peroxo-bis(pentacyanokobaltate(III)). Neuartige Darstellung,Beschreibung eines μ-Hydroperoxo-komplexes K5[Co2OOH(CN)10] · 2 H2O und eines μ-Peroxo-Carbonato-Komplexes K6[Co2CO4(CN)10] · 2 H2O

Investigations on Metal Catalysts. XXII. Chemisorption of Hydrogen on Pt? Ru and η-Al₂O₃ Supported Pt? Ru Catalysts Measurements of the H₂ chemisorption by volumetric method were carried out on several series of Pt? Ru and η-Al₂O₃ supported Pt? Ru catalysts. Addition of Ru to Pt and vice versa effects a remarkable influence on the sorption behaviour of the starting samples. For mixtures of carrier-free catalysts and η-Al₂O₃ as well as Pt? Ru/η-Al₂O₃ catalysts a hydrogen-spillover effect was found.     

Austauscher mit cyclischen Polyethern als Ankergruppen—II: Anwendungen

Exchangers with cyclic polyethers as anchor groups have a large range of applications such as separations of cations with a common anion, of anions with a common cation, and of neutral organic compounds, and the determination of water by elution chromatography. Some crown ether monomers, especially 4- and 4,4′-alkyl-substituted benzo-derivatives are suitable for extractions and their adducts with heteropoly acids are used as liquid ion-exchangers. The exchangers are also applied in thin-layer chromatography and thin-layer electrophoresis. Furthermore the exchangers are successfully used in preparative chemistry, e.g., in salt conversions in order to isolate salts which are difficult to prepare by other means, in isolation and purification of organic compounds, and for anion activation in organic reactions.     

On periodic subsolutions to steady second-order systems and applications

Bostan and Namah (Remarks on bounded solutions of steady Hamilton–Jacobi equations, C. R. Acad. Sci. Paris, Ser. I 347(15–16) (2009) 873–878) proved that constant functions are the only bounded solutions to $H(Du)=H(0)$ when H is superlinear and strictly convex. In this short note, we present a proof other than that of Bostan and Namah for equations that can be easily applied to some types of possibly degenerate parabolic systems. Our proof applies for periodic subsolutions instead of bounded solutions like that of Bostan and Namah; however, we need periodic subsolutions, which is quite restrictive. We do not consider Hopf–Lax's formula in our proof, so we can relax some restrictions on H. We also present an application to the large-time behavior of solutions to degenerate parabolic systems.