Iterative approaches for solving a multi-objective 2-dimensional vector packing problem

In this paper, we address a bi-objective 2-dimensional vector packing problem (Mo2-DBPP) that calls for packing a set of items, each having two sizes in two independent dimensions, say, a weight and a height, into the minimum number of bins. The weight corresponds to a “hard” constraint that cannot be violated while the height is a “soft” constraint. The objective is to find a trade-off between the number of bins and the maximum height of a bin. This problem has various real-world applications (computer science, production planning and logistics). Based on the special structure of its Pareto front, we propose two iterative resolution approaches for solving the Mo2-DBPP. In each approach, we use several lower bounds, heuristics and metaheuristics. Computational experiments are performed on benchmarks inspired from the literature to compare the effectiveness of the two approaches.     

Crack arrest and stress dependence of laser-induced surface damage in fused-silica and borosilicate glass

Results of experiments on stress-inhibited laser-driven crack growth and stress-delayed laser-damage initiation thresholds in fused silica, borosilicate glass (BK-7), and cleaved bulk silica are presented. A numerical model is developed to explain the crack arrest in fused silica. Good agreement is obtained between the model and a finite-element code. The crack arrest is demonstrated to be the result of the breaking of a hoop-stress symmetry that is responsible for crack propagation in fused silica.     

Effect of surface roughness and complex indices of refraction on polarized thermal emission

We present a series of measurements characterizing the dependence of polarized thermal emission on surface roughness. In particular, we measure the spectrally resolved degree of linear polarization (DOLP) for a series of roughened borosilicate (Pyrex) glass substrates as a function of the roughness parameter Ra, the root-mean-square slope distribution, and observation angle theta. Also measured are a series of smooth glass substrates coated with two particular polymers of interest, i.e., a common commercially available Krylon paint and a chemical-agent-resistant coating paint. The DOLP is measured over a 4-13 microm wave band by using a modified Fourier transform IR spectrometer in which a wire-grid polarizer and a quarter-wave Fresnel rhomb are used in conjunction to measure all four Stokes parameters. In addition, we show an enhanced DOLP due to anomalous dispersion exhibited by the surface material.     

In situ infrared aerosol spectroscopy for a variety of nerve agent simulants using flow-through photoacoustics

We present newly measured results of an ongoing experimental program established to measure optical cross sections in the mid- and long-wave infrared for a variety of chemically and biologically based aerosols. For this study we consider only chemically derived aerosols, and in particular, a group of chemical compounds often used as simulants for the detection of extremely toxic organophosphorus nerve agents. These materials include: diethyl methylphosphonate (DEMP), dimethyl methylphosphonate (DMMP), diisopropyl methylphosphonate (DIMP), and diethyl phthalate (DEP). As reported in a prior study [Appl. Opt. 44, 4001 (2005)], we combine two optical techniques well suited for aerosol spectroscopy [i.e., flow-through photoacoustics and Fourier transform infrared (FTIR) emission spectroscopy], to measure in situ the absolute extinction and absorption cross sections over a variety of wavelengths spanning the IR spectral region from 3 to 13 mum. Aerosol size distribution(s), particle number density, and dosimetric measurements are recorded simultaneously in order to present optical cross sections that are aerosol mass normalized, i.e., m(2)/gram. Photoacoustic results, conducted at a series of CO(2) laser lines, compare well with measured broadband FTIR spectral extinction. Both FTIR and photoacoustic data also compare well with Mie theory calculations based on measured size distributions and previously published complex indices of refraction.     

Improvements of the reactivity devices modeling for the advanced CANDU reactor

In the context of the ACR™ (Advanced CANDU Reactor), 3D transport calculations are required in order to simulate the reactivity devices located perpendicularly to the fuel channels. The computational scheme that is usually used for CANDU-6 and ACR reactors is based on a simplified supercell geometry in which the fuel clusters and devices are replaced by annuli. Recently, an exact modeling of 3D supercell configurations was introduced within the framework of the ACR calculations. However, with such a model, fine meshing requirements lead to problems that are very demanding in terms of computational resources.

In this paper, we present improvements introduced in the ACR context to reduce the cost of the 3D supercell calculations. Two avenues of investigations are reported. First, the introduction of an accelerated characteristics method permits to reduce the computational burden of such calculations involving a large number of regions. In addition, contrarily to CANDU-6 supercell configurations, the ACR 3D geometry is prismatic and consequently a special tracking procedure can be used. This approach introduces no approximation and is significantly faster than the general 3D tracking technique. Thanks to these modifications in the computational procedure, 3D supercell calculations with a level of mesh discretization comparable to 2D cell configurations become affordable for industrial applications.     

A simplified αβ based Gaussian sum filter

State estimation is a major problem in many fields, such as target tracking. For a linear Gaussian dynamic system, the KF provides the optimal state estimate, in the minimum mean square error sense. In general, however, real-world systems are governed by the presence of non-Gaussian noise and/or nonlinear systems. In this paper, the problem of state estimation in the case of a linear system affected by a non-Gaussian measurement noise is addressed. Based on the theoretical framework of the Gaussian sum filters (GSF), we propose a novel static version of this filter that uses the well known αβ filter. The simulation results show that the proposed filter has acceptable performances in terms of RMSE and a reduced computational load, compared to the classical GSF.     

Exponential inequalities for Mann’s stochastic algorithm

Abstract

In this article, we investigate the problem of approximating the fixed point for some function using a Mann iterative process with random errors. After establishing some exponential inequalities, we prove the complete convergence of Mann’s algorithm toward the fixed point and deduce a confidence interval for this one. In addition, we establish the convergence rate of Mann’s algorithm. Several numerical examples are sketched to illustrate the performance of the proposed algorithm.     

Antioxidant Activity of the Essential Oil and Oleoresin of Zingiber Officinale Roscoe as Affected by Chemical Environment

Three different biochemical test systems were chosen based on their solubility to study the antioxidant activity of ginger extracts. Reducing power and DPPH^. scavenging activity tests were considered to produce hydrophilic environments and the H₂O₂ test was considered as creating a lipophilic environment. The average yields were 10.23 ± 1.02% and 0.48 ± 0.19% for oleoresin and essential oil, respectively. The content of total phenols was 67.6 ± 1.08 mg GAE/g of dry extract. In terms of EC₅₀, in hydrophilic environment standards, it showed the highest effects compared to ginger extracts, with oleoresin presenting more activity than essential oil. In contrast, except for quercetin, essential oil showed the best scavenging activity in inhibiting H₂O₂ compared to all other antioxidants. The present work demonstrated that, when using reducing power, DPPH· free radical scavenging and H₂O₂ scavenging assays, the same ginger extracts exhibit different antioxidant activities, which were affected not only by the extract itself but also by the chemical environment (hydrophilic/lipophilic).     

Using speech rhythm knowledge to improve dysarthric speech recognition

We introduce a new framework to improve the dysarthric speech recognition by using the rhythm knowledge. This approach builds speaker-dependent (SD) recognizers with respect to the dysarthria severity level of each speaker. This severity level is determined by a hybrid classifier combining class posterior distributions and a hierarchical structure of multilayer perceptrons. To perform this classification, rhythm-based features are used as input parameters since the preliminary evidence from perceptual experiments shows that rhythm troubles may be the common characteristic of various types of dysarthria. Then, a speaker-dependent dysarthric speech recognition is performed by using Hidden Markov Models (HMMs). The Nemours database of American dysarthric speakers is used throughout experiments. Results show the relevance of rhythm metrics and the effectiveness of the proposed framework to improve the performance of dysarthric speech recognition.     

Biosorption of mercury from aqueous solutions by powdered leaves of castor tree (Ricinus communis L.)

A new biosorbent produced from castor leaves powder [Ricinus communis L.] was used to remove mercury(II) from aqueous solutions. The initial mercury concentrations, contact time and initial pH were evaluated. The ability of castor leaves to remove mercury at various pH (2-8) was studied. The maximum capacity (Qmax) of biomass was found to be 37.2mg Hg(II)/g at pH 5.5. Biosorption equilibrium was established in approximately 1h. The equilibrium data were described well by Langmuir and Freundlich models. The adsorbed mercury on biomass was desorbed using 10 ml of 4M HCl solution. The biomass could be reused for other biosorption assays. The ability of biomass to adsorb mercury(II) in a column was investigated. These studies consider the possibility of using leaves of castor tree as an inexpensive adsorbent for the removal of Hg(II) from contaminated chemical and mining industry wastewaters. It is also suggested that the dried biomass might be simply kept and used in a very low cost metal ion removal system.