May 20, 2013

A touch of Henry Moore and the Nits

Reclining figure, Henry Moore, Lincoln Center
New York could as well have been Dutch. In 1609, English explorer Henry Hudson (according to wikipedia): 
re-discovered the region, sailing for his employer the Dutch East India Company. He proceeded to sail up what he named the North River, also called the Mauritis River, and now known as the Hudson River, to the site of the present-day New York State capital of Albany in the belief that it might represent an oceanic tributary. When the river narrowed and was no longer saline, he realized it wasn't a sea passage and sailed back downriver. He made a ten-day exploration of the area and claimed the region for his employer. In 1614 the area between Cape Cod and Delaware Bay would be claimed by the Netherlands and called Nieuw-Nederland (New Netherland).
The capital of Nieuw-Nederland was located in the southern tip of Manhattan. A last proof is the New York City flag, derived from the Prince's flag, the flag of the Dutch republic (with the date of 1625).
There are many good reasons to go to New York City and send a lot of time strolling through this amazing city.  One of the reasons that led me to first ride on Greyhound on 1998 from Boston to New York is the album Nits in concert, which i bought earlier in a second-hand record shop in Boston. A relatively rare promo-CD where the Nits (a Dutch band) explain some of their songs' lyrics meanings. Which is a neat way to dive into their song writing atmosphere.

On Nits in concert,  there is a track called "A touch of Henry Moore", where they allude (lyrics) to a sculpture called "Reclining figure" (1965). It was 15 years ago at UNO headquarters, it now dwells at  the Lincoln Center. Here i was back again this Tuesday (picture on the top left).  I like this instrumentally minimalist version of "A touch of Henry Moore" (from album Omsk), which still evokes the hammering of a brass being. Another version used a large tube & pipe wall, My second best remains this one, in a more visually appealing vision with percussions on a  blocky squared wall.

May 16, 2013

Gas chromatography and 2D-gas chromatography for petroleum industry: The race for selectivity

Almost a follow-up to Signal Processing for Chemical Sensing: ICASSP 2013 Special session: the book Gas chromatography and 2D-gas chromatography for petroleum industry: The race for selectivity, edited by Fabrice Bertoncini, Marion Courtiade-Tholance, Didier Thiébaut (2013, éditions Technip) is out. Our contribution lies in Chapter 3: "Data processing applied to GCxGC. Applications to the petroleum industry.".
Detailed knowledge of petroleum products at molecular scale has always been essential to understand the mechanisms leading to their formation, to design thermodynamic and kinetic models employed in the refining processes and to predict their physical properties. In view of the complexity of petroleum products, very significant research efforts have been made over the past 15 years for improving relevant analytical techniques, especially in the field of Gas Chromatography in order to improve its separation power. The advent of comprehensive Two-dimensional Gas Chromatography (GC×GC) at the end of 1990's constitutes a true revolution allowing an unprecedented insight into very complex mixture at the molecular level.
This book aims at providing a complete review of the implementation of Gas Chromatography in the field of oil industry, with an important focus on GC×GC and related multidimensional systems. It is therefore organised into 8 chapters dealing with fundamental and experimental aspects as well as data processing challenges. Recent progress in the development of these chromatographic systems are discussed according to various applications: detailed molecular analysis of hydrocarbons, speciation of hetero-element, global properties calculation based on chromatographic data and simulated distillation. Specialists from IFP Energies nouvelles, CNRS and major companies leading important research in this field have contributed, reporting a synthesis of the knowledge acquired from research these last 15 years.
Thus, this book will be useful for anyone involved in the separation of oil and derivatives: the student starting a research project, the academic researcher and the refinery engineer willing to deepen their knowledge on advanced multidimensional Gas Chromatography, as well as molecular analysis of petroleum products.

 Contents: 1. Molecular analysis for petroleum products: challenges and future needs. 2. GCxGC: a disruptive technique. 3. Data processing applied to GCxGC. Applications to the petroleum industry. 4. Coupled systems with a CG or GCxGC dimension. 5. Detailed analysis of hydrocarbons. 6. Calculating properties from chromatographic data. 7. Speciation of heteroelements. 8. Simulated distillation. Index.
Related publications:  

Comprehensive Two-Dimensional Gas Chromatography for Detailed Characterisation of Petroleum Products ,Colombe Vendeuvre, R. Ruiz-Guerrero, Fabrice Bertoncini, Laurent Duval, Didier Thiébaut, Oil and Gas Science and Technology - Revue de l'IFP, Special issue on "Recent Advances in the Analysis of Catalysts and Petroleum Products", 2007, Vol. 62, n°01, p. 043-055
Comprehensive two-dimensional gas chromatography (GC xGC or GC2D) is a major advance for the detailed characterisation of petroleum products. This technique is based on two orthogonal dimensions of separation achieved by two chromatographic capillary columns of different chemistries and selectivities. High-frequency sampling between the two columns is achieved by a modulator, ensuring that the whole sample is transferred and analysed continuously in both separations. Thus, the peak capacity and the resoluting power dramatically increase. Besides, highly structured 2D chromatograms are obtained upon the volatility and the polarity of the solute to provide more accurate molecular identification of hydrocarbons. In this paper fundamental and practical considerations for implementation of GCxGC are reviewed. Selected applications obtained using a prototype of a GCxGC chromatograph developed in-house highlight the potential of the technique for molecular characterisation of middle distillates, sulphur speciation in diesel and analysis of effluents frompetrochemical processes
Characterization of middle-distillates by comprehensive two-dimensional gas chromatography (GCxGC): a powerful alternative for performing various standard analysis of middle distillates (pdf), Colombe Vendeuvre, Rosario Ruiz-Guerrero, Fabrice Bertoncini, Laurent Duval, Didier Thiébaut, Marie-Claire Hennion, Journal of Chromatography A, 1086 (2005) p. 21-28
The detailed characterisation of middle distillates is essential for a better understanding of reactions involved in refining process. Owing to higher resolution power and enhanced sensitivity, comprehensive two-dimensional gas chromatography (GCxGC) is a powerful tool for improving characterisation of petroleum samples. The aim of this paper is to compare GCxGC and various ASTM methods – gas chromatography (GC), liquid chromatography (LC) and mass spectrometry (MS) – for group type separation and detailed hydrocarbon analysis. Best features of GCxGC are demonstrated and compared to these techniques in terms of cost, time consumption and accuracy. In particular, a new approach of simulated distillation (SimDis-GCxGC) is proposed: compared to the standard method ASTM D2887 it gives unequal information for better understanding of conversion process.
Comparison of conventional gas chromatography and comprehensive two-dimensional gas chromatography for the detailed analysis of petrochemical samples (pdf), Colombe Vendeuvre, Fabrice Bertoncini, Laurent Duval, Jean-Luc Duplan, Didier Thiébaut, Marie-Claire Hennion, Journal of Chromatography A, 1056 (2004) p. 155-162
Comprehensive two-dimensional gas chromatography (GCxGC) has been investigated for the characterization of high valuable petrochemical samples from dehydrogenation of n-paraffins, Fischer–Tropsch and oligomerization processes. GCxGC separations, performed using a dual-jets CO2 modulator, were optimized using a test mixture representative of the hydrocarbons found in petrochemicals. For complex samples, a comparison of GCxGC qualitative and quantitative results with conventional gas chromatography (1D-GC) has demonstrated an improved resolution power of major importance for the processes: the group type separation has permitted the detection of aromatic compounds in the products from dehydrogenation of n-paraffins and from oligomerization, and the separation of alcohols from other hydrocarbons in Fischer–Tropsch products.

May 4, 2013

Signal Processing for Chemical Sensing: ICASSP 2013 Special session

ICASSP 2013 (International conference on acoustic, speech and signal processing) takes place at the end of May 2013 in Vancouver, Canada. The technical program is online.

Among the numerous tracks and sessions, there were a special session on Signal Processing for Chemical Sensing (Friday, May 31, 08:00 - 10:00). The chairpersons were: Leonardo T. Duarte, Laurent Duval, Christian Jutten. Here are posted the slides (all slides in a .zip file) presented at the conference and paper abstracts.

Typical chemical signals: 1D gas chromatogram
Summary of the Special Session:
This special session aims at showing some relevant problems in chemical engineering that can be addressed with classical or advanced methods of signal and image processing. It will be introduced by a tutorial paper, presented by the organizers, who will offer a large overview of issues which have been addressed in this application domain, like chemical analysis leading to PARAFAC/tensor methods, hyper spectral imaging, ion-sensitive sensors, artificial nose, chromatography, mass spectrometry, TEP imaging, etc. For enlarging and illustrating the points of view of the tutorial, the invited papers of the session consider other applications (NMR, Raman spectroscopy, recognition of explosive compounds, etc.) addressed  by various methods, e.g. source separation, Bayesian or EMD, and exploiting priors like positivity, unit-concentration or sparsity. 
Typical chemical signals: 2D comprehensive gas chromatogram (GCxGC)
Motivation and rationale of the Special Session:
With the advent of more affordable, higher resolution or innovative data acquisition techniques, chemical analysis has  been using progressively advanced signal and image processing tools. This crucial need is exemplified in the Savitzky-Golay filter, which recently was thoroughly revisited  by R. W. Schafer ("What Is a Savitzky-Golay Filter?", Signal Processing Magazine, Jul. 2011). Indeed, both specialities (analytical chemistry and signal processing) share similar values of best practice in carrying out identifications and comprehensive characterizations, albethey of chemical  samples or of numerical data. Signal and image processing, for instance, often breaks down data into atoms, molecules, with specific decompositions and priors, as common in chemistry.

This special session will gather a representative sample of recent works in chemical sensing, aiming at introducing its  specific challenges to a broader signal processing audience, for the benefits of both domains.

Papers (upcoming)

Laurent Duval, Leonardo Duarte, Christian Jutten (paper)
Abstract: This tutorial paper aims at summarizing some  problems, ranging  from  analytical chemistry to novel chemical sensors, that can be addressed with classical or advanced methods of signal and image processing. We gather them under the denomination of "chemical sensing". It is meant to introduce the special session "Signal Processing for Chemical Sensing" with a large overview of issues which have been and remain to be addressed in this application domain, including chemical analysis leading to PARAFAC/tensor methods, hyper spectral imaging, ion-sensitive sensors, artificial nose, chromatography, mass spectrometry, etc.  For enlarging and illustrating the points of view of this tutorial, the  invited papers of the session consider other applications (NMR, Raman spectroscopy, recognition of explosive compounds, etc.) addressed  by various methods, e.g. source separation, Bayesian, and exploiting typical chemical signal priors like positivity, linearity, unit-concentration or sparsity.
Keywords: Chemical analysis, Chemical sensors, Gas chromatography, Signal processing algorithms, Spectroscopy
Paper: An overview of signal processing issues in chemical sensing (HAL)
Slides: ICASSP-2013-Duarte-overview-signal-processing-chemical-sensing.pdf

Abstract: This paper deals with the reconstruction of relaxation time distributions in Nuclear Magnetic Resonance (NMR) spectroscopy. This large scale and ill-posed inverse problem is solved by the iterative minimization of a regularized objective function allowing to encode some prior assumptions on the sought distribution. The numerical optimization of the criterion is performed using a primal-dual interior point algorithm allowing to handle the non-negativity constraint. The performances of the proposed approach are illustrated through the processing of real data from a two-dimensional NMR experiment.
Keywords: T1-T2 relaxation times, Laplace transform inversion, interior-point, primal-dual, preconditioning
Paper: Primal-DualInterior Point Optimization for a Regularized Reconstruction of NMRRelaxation Time Distributions
Slides: ICASSP-2013-Moussaoui-NMR-Primal-Dual.pdf
Abstract: We propose a sparse modal estimation approach for analyzing 2-D NMR signals. It consists in decomposing the 2-D problem into two 1-D modal estimations. Each 1-D problem is formulated in terms of simultaneous sparse approximation which is efficiently solved using the Simultaneous Orthogonal Matching Pursuit method associated with a multi-grid dictionary refinement. Then, we propose a new criterion for mode pairing which comes down to solve a sparse approximation problem involving a low dimensional dictionary. The effectiveness of the method is demonstrated on real NMR data.
Keywords: Modal retrieval, sparse approximation, multi-grid, 2-D NMR
Paper: Sparse modal estimation of 2-D NMR signals
Slides: ICASSP-2013-Brie-Sparse-Modal-2d-NMR.pdf
Abstract: New sensor technologies such as Fabry-Pérot interferometers (FPI) offer low-cost and portable alternatives to traditional infrared absorption spectroscopy for chemical analysis. However, with FPIs the absorption spectrum has to be measured one wavelength at a time. In this work, we propose an active-sensing framework to select a subset of wavelengths that best separates the specific components of a chemical mixture. Compared to passive feature selection approaches, in which the subset is selected offline, active sensing selects the next feature on-the-fly based on previous measurements so as to reduce uncertainty. We propose a novel multi-modal non-negative least squares method (MM-NNLS) to solve the underlying linear system, which has multiple near optimal solutions. We tested the framework on mixture problems of up to 10 components from a library of 100 chemicals. MMNNLS can solve complex mixtures using only a small number of measurements, and outperforms passive approaches in terms of sensing efficiency and stability.
Keywords: Active sensing, tunable sensors, multi-modal optimization, chemical mixture analysis
Paper:  Active analysis of chemical mixtures with multi-modal sparse non-negative least squares
Slides: ICASSP-2013-Gutierrez-Osuna-active-multi-modal.pdf
Abstract: In this paper, a novel gas identification approach based on the Recursive Least Squares (RLS) algorithm is proposed. We detail some adaptations of RLS to be applied to a sensor matrix of several technologies in optimal conditions. The low complexity of the algorithm and its ability to process online samples from multi-sensor make the real-time identification of volatile compounds possible. The effectiveness of this approach to early detect and recognize explosive compounds in the air has been successfully demonstrated on an experimentally obtained dataset.
Keywords: Electronic nose, Pattern recognition, Multidimensional analysis, Recursive Least Squares
Slides: ICASSP-2013-Mayoue-recursive-least-squares.pdf
Three others ICASSP 2013 papers are closely related to the topic of chemical sensing and signal processing:
Earlier post: ICASSP 2013: Special sessions   

Related post :  Gas chromatography and 2D-gas chromatography for petroleum industry: The race for selectivity