The use of FDTD for the analysis of magnetoplasma channelwaveguides

The finite-difference time-domain (FDTD) method is used for the analysis of magnetoplasma rectangular channel waveguides. Single and parallel-coupled waveguides are considered. The effect of varying the amplitude and the orientation of the bias magnetic field B₀ on the dispersion characteristics of the first modes is examined. However, the FDTD formulation, does not excite evanescent modes for a sufficiently long time interval, particularly when in the presence of the propagating or dynamic modes. As a result, the nonreciprocal properties of these structures, primarily associated with the evanescent modes, could not be investigated     

Understanding the Efficiency of kD-tree Ray-Traversal Techniques over a GPGPU Architecture

Current GPU computational power enables the execution of complex and parallel algorithms, such as ray tracing techniques supported by kD-trees for 3D scene rendering in real time. This work describes in detail the study and implementation of eight different kD-tree traversal algorithms using the parallel framework NVIDIA Compute Unified Device Architecture, in order to point their pros and cons regarding performance, memory consumption, branch divergencies and scalability on multiple GPUs. In addition, two new algorithms are proposed by the authors based on this analysis, aiming to performance improvement. Both of them are capable of reaching speedup gains up to 3 × when compared to recent and optimized parallel traversal implementations. As a consequence, interactive frame rates are possible for scenes with 1,408 × 768 pixels of resolution and 3.6 million primitives.     

Output feedback control of Markov jump linear systems incontinuous-time

This paper addresses the dynamic output feedback control problem of continuous-time Markovian jump linear systems. The fundamental point in the analysis is an LMI characterization, comprising all dynamical compensators that stabilize the closed-loop system in the mean square sense. The H₂ and H_∞-norm control problems are studied, and the H₂ and H_∞ filtering problems are solved as a by product     

Characterization and activity of vanadia-promoted Pt/ZrO2 catalysts for the water–gas shift reaction

Pt/ZrO₂ catalysts for the water–gas shift (WGS) were promoted with various amounts of vanadia. Analyses by XRD, N₂ adsorption, Raman, and UV–vis DRS showed that vanadia is present below monolayer coverage as monovanadate and polyvanadate, with the former dominating at lower loadings, and that following monolayer formation, VO₅ species appear, with the eventual generation of V₂O₅ and ZrV₂O₇ for a vanadia weight loading of 13%. Though in all cases vanadia induced an enhancement in WGS activity, the best catalyst, that contained 3 wt.% of vanadia, gave a rate that was nearly double that of the unpromoted Pt/ZrO₂. That superior global activity probably results from the monovanadate that is the main species at low loadings. It is believed that monovanadate promotes the WGS by rendering the support's surface more oxidizing through its VOZr bonds.     

Analytical optimal solution of the extension of the depth of field using cubic-phase wavefront coding. Part I. Reduced-complexity approximate representation of the modulation transfer function

In this paper we derive an approximate analytical representation for the modulation transfer function (MTF) of an imaging system possessing a defocused cubic-phase pupil function. This expression is based on an approximation using the Arctan function and significantly reduces the computational time required to calculate the resulting MTF. We derive rigorous bounds on the minimum and average accuracy of our approximation. Using this approximate representation of the MTF, the analytical solution of the problem of calculating the extension of the depth of field for a circular aperture with a cubic phase mask becomes possible. We also comment on how one can modify our method to construct a lower-bound or an upper-bound approximate analytical expression for the MTF.     

Functionalized Multiwalled Carbon Nanotube Electrochemical Sensor for Determination of Anticancer Drug Flutamide

An electrochemical sensor based on functionalized multiwalled carbon nanotubes (MWCNT_f) has been developed and applied for determination of anticancer drug flutamide in pharmaceutical and artificial urine samples. The electrode was prepared by modifying a glassy carbon electrode with MWCNT_f, denoted herein as MWCNT_f/GCE. The MWCNT_f/GCE electrode exhibited high catalytic activity, high sensitivity, and high stability and was applicable over a wide concentration range for flutamide. The effects of the scan rate, pH, and nature of the electrolyte on the electrochemical behavior of flutamide on the MWCNT_f/GCE were investigated. The results showed that this electrode presented the best square-wave voltammetric response to flutamide in Britton–Robinson buffer solution at pH 5.0 at frequency of 50 Hz and amplitude of 0.06 V. The proposed sensor presents a wide linear response range from concentration of 0.1 μmol L^?1 up to 1000 μmol L^?1 (or 27.6 μg L^?1 up to 0.27 g L^?1), with limit of detection, limit of quantification, and sensitivity of 0.03 μmol L^?1, 0.1 μmol L^?1, and 0.30 μA μmol^?1 L, respectively. The MWCNT_f/GCE electrode was successfully applied for determination of flutamide in pharmaceutical formulations and artificial urine samples, giving results in agreement with those obtained by a comparative method described in literature. A paired Student’s t-test revealed no statistical difference between the reference and proposed method at 95% confidence level. The average recovery for fortified samples was 101 ± 1%.