The fully implicit stochastic-alpha method for stiff stochastic differential equations

A fully implicit integration method for stochastic differential equations with significant multiplicative noise and stiffness in both the drift and diffusion coefficients has been constructed, analyzed and illustrated with numerical examples in this work. The method has strong order 1.0 consistency and has user-selectable parameters that allow the user to expand the stability region of the method to cover almost the entire drift-diffusion stability plane. The large stability region enables the method to take computationally efficient time steps. A system of chemical Langevin equations simulated with the method illustrates its computational efficiency.

An Input Triggered Polymorphic ASIC for H.264 Decoding

This paper reports the design of an input-triggered polymorphic ASIC for H.264 baseline decoder. Hardware polymorphism is achieved by selectively reusing hardware resources at system and module level. Complete design is done using ESL design tools following a methodology that maintains consistency in testing and verification throughout the design flow. The proposed design can support frame sizes from QCIF to 1080p.

Soft gluon k(t)-resummation and the Froissart bound

We study soft gluon k(t)-resurnmation and the relevance of InfraRed (IR) gluons for the energy dependence of total hadronic cross-sections. In our model, consistency with the Froissart bound is directly related to the ansatz that the IR behaviour of the QCD coupling constant follows an inverse power law.

Fluorescence polarization as a tool to study lectin-sugar interaction. An investigation of the binding of 4-methylumbelliferyl beta-D-galactopyranoside to Abrus precatorious agglutinin

Polarization of ligand fluorescence was used to study the binding of 4-methylumbelliferyl beta-D-galactopyranoside (MeUmb-Galp) to Abrus precatorious agglutinin. The binding of the fluorescent sugar to the lectin led to considerable polarization of the MeUmb-Galp fluorescence, which was also quenched by about 30% on binding to the lectin. The binding of the fluorescent sugar was carbohydrate-specific, as evidenced by inhibition of both fluorescence polarization and quenching when lectin was preincubated with lactose. The association constant as determined by fluorescence polarization is 1.42 x 10(4) M-1 at 25 degrees C and is in excellent agreement with those determined by fluorescence quenching (Ka = 1.51 x 10(4) M-1) and equilibrium dialysis (Ka = 1.62 x 10(4) M-1) at 25 degrees C. The numbers of binding sites as determined by fluorescence polarization, quenching and equilibrium dialysis agree very well with one another, n being equal to 2.0 +/- 0.05. The consistency between the association constant value determined by fluorescence polarization, quenching and equilibrium dialysis shows the validity of this approach to study lectin-sugar interaction.

Performance Analysis of Reconstruction Techniques for Frequency-Domain Optical-Coherence Tomography

We address the issue of noise robustness of reconstruction techniques for frequency-domain optical-coherence tomography (FDOCT). We consider three reconstruction techniques: Fourier, iterative phase recovery, and cepstral techniques. We characterize the reconstructions in terms of their statistical bias and variance and obtain approximate analytical expressions under the assumption of small noise. We also perform Monte Carlo analyses and show that the experimental results are in agreement with the theoretical predictions. It turns out that the iterative and cepstral techniques yield reconstructions with a smaller bias than the Fourier method. The three techniques, however, have identical variance profiles, and their consistency increases linearly as a function of the signal-to-noise ratio.

Consistent quaternion interpolation for objective finite element approximation of geometrically exact beam

We explore an isoparametric interpolation of total quaternion for geometrically consistent, strain-objective and path-independent finite element solutions of the geometrically exact beam. This interpolation is a variant of the broader class known as slerp. The equivalence between the proposed interpolation and that of relative rotation is shown without any recourse to local bijection between quaternions and rotations. We show that, for a two-noded beam element, the use of relative rotation is not mandatory for attaining consistency cum objectivity and an appropriate interpolation of total rotation variables is sufficient. The interpolation of total quaternion, which is computationally more efficient than the one based on local rotations, converts nodal rotation vectors to quaternions and interpolates them in a manner consistent with the character of the rotation manifold. This interpolation, unlike the additive interpolation of total rotation, corresponds to a geodesic on the rotation manifold. For beam elements with more than two nodes, however, a consistent extension of the proposed quaternion interpolation is difficult. Alternatively, a quaternion-based procedure involving interpolation of relative rotations is proposed for such higher order elements. We also briefly discuss a strategy for the removal of possible singularity in the interpolation of quaternions, proposed in [I. Romero, The interpolation of rotations and its application to finite element models of geometrically exact rods, Comput. Mech. 34 (2004) 121–133]. The strain-objectivity and path-independence of solutions are justified theoretically and then demonstrated through numerical experiments. This study, being focused only on the interpolation of rotations, uses a standard finite element discretization, as adopted by Simo and Vu-Quoc [J.C. Simo, L. Vu-Quoc, A three-dimensional finite rod model part II: computational aspects, Comput. Methods Appl. Mech. Engrg. 58 (1986) 79–116]. The rotation update is achieved via quaternion multiplication followed by the extraction of the rotation vector. Nodal rotations are stored in terms of rotation vectors and no secondary storages are required.

Dynamics and control of buckling type devices using SMA wire integrated beam

An analysis and design study using Shape Memory Alloy (SMA) wire integrated beam and its buckling shape control are reported. The dynamical system performance is analyzed with a mathematical set-up involving nonlocal and rate sensitive kinetics of phase transformation in the SMA wire. A standard phenomenological constitutive model reported by Brinson (1993) is modified by considering certain consistency conditions in the material property tensors and by eliminating spurious singularity. Considering the inhomogeneity effects, a finite element model of the SMA wire is developed. Simulations are carried out to study the buckling shape control of a beam integrated with SMA wire.