Blind separation of vibration signals and source change detection – Application to machine monitoring

The paper presents a new approach for machine vibration analysis and health monitoring combining blind source separation (BSS) and change detection in source signals. So, the problem is transferred from the original space of the measurements to the space of independent sources, where the reduced number of components is going to simplify the monitoring problem while the change detection methods are going to be applied for scalar signals. The assessment of the approach on a real machine is presented in this paper.     

XPS study on surface modification of NiTi alloy by acidic solution immersion and subsequent heating in air

Changes in the surface chemical state of a nearly equiatomic nickel–titanium (NiTi) alloy caused by immersion in aqueous solutions of HNO₃ and H₂SO₄ as well as subsequent heating in air at 723 K were analyzed using X-ray photoelectron spectroscopy (XPS). An XPS analysis using angle-resolved technique and a mathematical deconvolution technique revealed that a passive layer formed in an ambient atmosphere contained TiO₂ as a major state and Ni(OH)₂ and NiO as minor states. The Ni(OH)₂ on the alloy remained in the region even when heated in air at 723 K. Therefore, the resulting layer became a Ti-oxide layer with Ni segregated region at the surface, which was NiO formed via dehydration of Ni(OH)₂. However, immersion in an aqueous solution of HNO₃ or H₂SO₄ enables Ni(OH)₂ state to dissolve in the passive layer of a NiTi alloy; thereby, the Ni segregated region rarely appeared in the oxide layer by heating. The Ni segregated region at the surface becomes an obstacle for the inward diffusion of oxygen; thus, the annihilation of such a segregated region results in an increase in the thickness of the oxide layer.     

Atomic resolution imaging of oxygen atoms close to heavy atoms by HRTEM and ED,using the superconductor SmFeAsO0.85F0.15 as an example

Imaging of light atoms has always been a challenge in high-resolution electron microscopy. Image resolution is mainly limited by lens aberrations, especially the spherical aberration of the objective lens. Image deconvolution could correct for the image distortion by lens aberrations and restore the structure projection, the resolution of which is limited by the information limit of the microscope. Electron diffraction unrestricted by lens aberrations could overcome this resolution limit. Here we show a combination of electron diffraction and image deconvolution to reveal simultaneously the atomic columns of O and considerably heavier Sm at a very close distance (1.17 Å) in iron-based superconductor SmFeAsO_0.85F_0.15 using a conventional 200 kV electron microscope. The approach used here, starting from an image and an electron diffraction pattern, has an advantage for those radiation-sensitive samples. Besides, it can be applied to simultaneously imaging light and heavy atoms, even though they have a big difference in atomic number and a much smaller atomic distance than the microscope resolution.     

On the convergence of an approximate deconvolution model to the 3D mean Boussinesq equations

In this paper, we study an LES model for the approximation of large scales of the 3D Boussinesq equations. This model is obtained using the approach first described by Stolz and Adams, based on the Van Cittern approximate deconvolution operators, and applied to the filtered Boussinesq equations. Existence and uniqueness of a regular weak solution are provided. Our main objective is to prove that this solution converges towards a solution of the filtered Boussinesq equations, as the deconvolution parameter goes to zero. Copyright © 2014 John Wiley & Sons, Ltd.     

Energy analysis and improved regularity estimates for multiscale deconvolution models of incompressible flows

This paper presents new analytical results and the first numerical results for a recently proposed multiscale deconvolution model (MDM) recently proposed. The model involves a large‐eddy simulation closure that uses a novel deconvolution approach based on the introduction of two distinct filtering length scales. We establish connections between the MDM and two other models, and, on the basis of one of these connections, we establish an improved regularity estimate for MDM solutions. We also prove that the MDM preserves Taylor‐eddy solutions of the Navier–Stokes equations and therefore does not distort this particular vortex structure. Simulations of the MDM are performed to examine the accuracy of the MDM and the effect of the filtering length scales on energy spectra for three‐dimensional homogeneous and isotropic flows. Numerical evidence for all tests clearly indicates that the MDM gives very accurate coarse‐mesh solutions and that this multiscale approach to deconvolution is effective. Copyright © 2015 John Wiley & Sons, Ltd.     

Automated instrumental method for on-line fraction analysis and peak deconvolution in gradient multicomponent overloaded high performance liquid chromatography

An automated method for deconvolution of overloaded band profiles in gradient elution is described. The instrumental set-up consists of a pseudo-bidimensional HPLC system, where overloaded band profiles generated in the first direction are sampled on the second one. The method, previously employed under isocratic conditions, has been now extended to gradient elution, where one has to face the problem of band compression (and possibly band interference) during gradient, which decreases the time-window available along the first direction for sampling the overloaded profiles. The effect of the gradient steepness on the problem of defining a minimum number of sampling points to reconstruct single component bands from overloaded profiles is investigated. This approach is particularly useful in the framework of using inverse method (IM) to determine adsorption isotherm parameters for preparative gradient elution. In fact, it allows for the gathering of the information necessary to run IM calculations with minimum efford, also in cases where the individual component forming the mixture have different UV spectra.     

One‐dimensional small‐angle X‐ray scattering tomography of dip‐coated polyamide 6 monofilaments

A synchrotron study is presented in which the concept of one‐dimensional tomographic reconstruction of small‐angle X‐ray scattering patterns is applied to investigate polyamide 6 monofilaments, dip‐coated with alumina particles. The filaments are scanned with a focused synchrotron beam and the resulting scattering patterns are recorded with a PILATUS 2M detector. The reconstructed sequence of SAXS images reflects the local nanostructure variation along the filament radius. In particular, the influence of coating process parameters on the polyamide 6 is investigated.     

Estimation of speed of sound in dual-layered media using medical ultrasound image deconvolution

The speed of sound in soft tissues is usually assumed to be 1540 m/s in medical pulse-echo ultrasound imaging systems. When the true speed is different, the mismatch can lead to distortions in the acquired images, and so reduce their clinical value. Previously we reported a new method of sound-speed estimation in the context of image deconvolution. Unlike most other sound-speed estimation methods, this enables the use of unmodified ultrasound machines and a normal scanning pattern. Our approach was validated for largely homogeneous media with single sound speeds. In this article, we demonstrate that sound speeds of dual-layered media can also be estimated through image deconvolution. An ultrasound simulator has been developed for layered media assuming that, for moderate speed differences, the reflection at the interface may be neglected. We have applied our dual-layer algorithm to simulations and in vitro phantoms. The speed of the top layer is estimated by our aforesaid method for homogeneous media. Then, when the layer boundary position is known, a series of deconvolutions are carried out with dual-layered point-spread functions having different lower-layer speeds. The best restoration is selected using a correlation metric. The error level (e.g., a mean error of −9 m/s with a standard deviation of 16 m/s) for in vitro phantoms is found to be not as good as that of our single-speed algorithm, but is comparable to other local speed estimation methods where the data acquisition may not be as simple as in our proposed method.     

Sequential stir bar extraction,thermal desorption and retention time locked GC–MS for determination of pesticides in water

A method based on sequential stir bar sorptive extraction followed by automated thermal desorption–GC–MS for the determination of pesticides in underground and superficial water samples has been developed. Retention time locked GC–MS and deconvolution Automated Mass Spectral Deconvolution and Identification System software allows the use of pesticide databases for identification and quantification in routine applications. Quantitation limits and repetitivity using full scan mass spectrometric determination guarantee the applicability of the method, which enables considerable savings to be made in total analysis time, with data processing times of around 2 min/sample.     

Combined Wavelet Transform with Curve‐fitting for Objective Optimization of the Parameters in Fourier Self‐deconvolution

Fourier self‐deconvolution was the most effective technique in resolving overlapping bands, in which deconvolution function results in deconvolution and apodization smoothes the magnified noise. Yet, the choice of the original half‐width of each component and breaking point for truncation is often very subjective. In this paper, the method of combined wavelet transform with curve fitting was described with the advantages of an enhancement of signal to noise ratio as well as the improved fitting condition, and was applied to objective optimization of the original half‐widths of components in unresolved bands for Fourier self‐deconvolution. Again, a noise was separated from a noisy signal by wavelet transform, therefore, the breaking point of apodization function can be determined directly in frequency domain. Accordingly, some artifacts in Fourier self‐deconvolution were minimized significantly.