A new IMM algorithm using fixed coefficients filters (fastIMM)

In this paper we present an new approach based on two filters αβ$\alpha \beta$ and αβγ$\alpha \beta \gamma$ using Interacting Multiples Models (IMM) design instead of a Kalman filter second and third order for the tracking a single maneuver target. The comparison between the proposed filter and the IMM improves the computing time amount about 60% while having a high accuracy.     

Measured infrared optical cross sections for a variety of chemical and biological aerosol simulants

We conducted a series of spectral extinction measurements on a variety of aerosolized chemical and biological simulants over the spectral range 3-13 microm using conventional Fourier-transform IR (FTIR) aerosol spectroscopy. Samples consist of both aerosolized particulates and atomized liquids. Materials considered include Bacillus subtilis endospores, lyophilized ovalbumin, polyethylene glycol, dimethicone (SF-96), and three common background materials: kaolin clay (hydrated aluminum silicate), Arizona road dust (primarily SiO2), and diesel soot. Aerosol size distributions and mass density were measured simultaneously with the FTIR spectra. As a result, all optical parameters presented here are mass normalized, i.e., in square meters per gram. In an effort to establish the utility of using Mie theory to predict such parameters, we conducted a series of calculations. For materials in which the complex indices of refraction are known, e.g., silicone oil (SF-96) and kaolin, measured size distributions were convolved with Mie theory and the resultant spectral extinction calculated. Where there was good agreement between measured and calculated extinction spectra, absorption, total scattering, and backscatter were also calculated.     

Mechanical stresses and crack analysis of concrete under the hygrothermic effect

The hygrothermal process can change the porosity and the permeability of concrete, causing the initiation and the growth of the cracks, and thus deteriorating the integrity of the concrete structure. A numerical formulation based on the finite element method is developed to carry out the simulation of the initiation and the propagation of the cracks caused by the coupled field of thermal transfer and moisture transport. An original concept based on three-dimensional stress state of the integration points in each finite element is described. The global relative crack density is used to denote the cracking state of the entire concrete structure, which may serve as an appropriate index to evaluate the overall deterioration level of the structure.     

In situ measurement of the infrared absorption and extinction of chemical and biologically derived aerosols using flow-through photoacoustics

In an effort to establish a more reliable set of optical cross sections for a variety of chemical and biological aerosol simulants, we have developed a flow-through photoacoustic system that is capable of measuring absolute, mass-normalized extinction and absorption cross sections. By employing a flow-through design we avoid issues associated with closed aerosol photoacoustic systems and improve sensitivity. Although the results shown here were obtained for the tunable CO2 laser waveband region, i.e., 9.20-10.80 microm, application to other wavelengths is easily achievable. The aerosols considered are categorized as biological, chemical, and inorganic in origin, i.e., Bacillus atrophaeus endospores, dimethicone silicone oil (SF-96 grade 50), and kaolin clay powder (alumina and silicate), respectively. Results compare well with spectral extinction measured previously by Fourier-transform infrared spectroscopy. Comparisons with Mie theory calculations based on previously published complex indices of refraction and measured size distributions are also presented.     

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.     

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.     

Combining scanning probe microscopy and x-ray spectroscopy

A new versatile tool, combining Shear Force Microscopy and X-Ray Spectroscopy was designed and constructed to obtain simultaneously surface topography and chemical mapping. Using a sharp optical fiber as microscope probe, it is possible to collect locally the visible luminescence of the sample. Results of tests on ZnO and on ZnWO4 thin layers are in perfect agreement with that obtained with other conventional techniques. Twin images obtained by simultaneous acquisition in near field of surface topography and of local visible light emitted by the sample under X-Ray irradiation in synchrotron environment are shown. Replacing the optical fibre by an X-ray capillary, it is possible to collect local X-ray fluorescence of the sample. Preliminary results on Co-Ti sample analysis are presented.     

Modeling reactivity devices for advanced CANDU reactors using the code DRAGON

Full core analysis of typical power reactors generally performed uses few group diffusion theory, it is necessary to generate beforehand, using a lattice code, the required few group cross-sections and diffusion coefficients associated with each region in the core.

For the ACR™ (Advanced CANDU Reactor), the problem is more complex because these reactors contain vertical reactivity devices that are located between two horizontal fuel bundles. The usual calculation scheme relies in this case on a 2D fuel cell calculation to generate the few group fuel properties and on a 3D supercell calculation for the analysis of the reactivity devices present in the core. Because of its complexity, the supercell calculations have usually been performed using simplified fuel geometries. The development of new geometry features in DRAGON and the availability of faster computers have made it possible to improve the 2D cell and 3D supercell models by using explicitly 3D assemblies of clusters to simulate the reactivity devices in CANDU reactors, including the ACR. These studies will thus improve the fine reactor core results by generating more accurate and appropriate reactor databases.

In this paper, we will review the lattice-cell/supercell calculation procedure using the code DRAGON by introducing a new supercell model. The use of such an explicit 3D geometry implies a very fine spatial mesh discretization that can generate a large number of regions leading to problems that cannot be solved by the collision probability (CP) method. The method of characteristics (MoC) is then the only alternative for such cases. A comparison of results using these two methods will also be presented for 3D models with a coarse mesh discretization.