Applications of Kalman filtering to real-time trace gas concentration measurements.

Rice Quantum Institute, Rice University, Houston, TX 77251-1892, USA.
Applied Physics B (Impact Factor: 1.63). 02/2002; 74(1):85-93. DOI: 10.1007/s003400100751
Source: PubMed

ABSTRACT A Kalman filtering technique is applied to the simultaneous detection of NH3 and CO2 with a diode-laser-based sensor operating at 1.53 micrometers. This technique is developed for improving the sensitivity and precision of trace gas concentration levels based on direct overtone laser absorption spectroscopy in the presence of various sensor noise sources. Filter performance is demonstrated to be adaptive to real-time noise and data statistics. Additionally, filter operation is successfully performed with dynamic ranges differing by three orders of magnitude. Details of Kalman filter theory applied to the acquired spectroscopic data are discussed. The effectiveness of this technique is evaluated by performing NH3 and CO2 concentration measurements and utilizing it to monitor varying ammonia and carbon dioxide levels in a bioreactor for water reprocessing, located at the NASA-Johnson Space Center. Results indicate a sensitivity enhancement of six times, in terms of improved minimum detectable absorption by the gas sensor.

1 Bookmark
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Climacteric fruit ripening, as it occurs in many fruit crops, depends on a rapid, autocatalytic increase in ethylene production. This agriculturally important process has been studied extensively, with tomato simultaneously acting both as a model species and target crop for modification. In tomato, the ethylene biosynthetic genes ACC SYNTHASE2 (ACS2) and ACS4 are highly expressed during fruit ripening, with a combined loss of both ACS2 and ACS4 activity preventing generation of the ethylene burst necessary for fruit ripening. However, the individual roles and importance of ACS2 and ACS4 have not been determined. In this study, we examined specifically the role of ACS4 by comparing the phenotype of an acs4 mutant firstly with that of the wild-type, and secondly with two novel ripening-inhibitor (rin) mutants. Ethylene production during ripening was significantly reduced in both acs4-1, and rin lines, with rin genotypes showing the weaker ethylene burst. Also i) the time between anthesis and the start of fruit ripening and ii) the time required to progress through ripening were significantly longer in acs4-1 than in the wild type, but shorter than in the strongest rin mutant. The delay in ripening was reflected in the lower expression of ripening-related transcripts during the mature green and light red ripening stages. Furthermore, expression of ACS2 and ACS4 was strongly dependent on a functional RIN gene, while ACS2 expression was largely independent of ACS4. Altogether, we show that ACS4 is necessary for normal progression of tomato fruit ripening and that mutation of this gene may provide a useful means for altering ripening traits.
    Frontiers in Plant Science 09/2014; · 3.64 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: In the current paper a non-linear load control method is developed and implemen-ted for a permanent magnet linear synchronous motor (PMLSM) with a flexible load. The pro-posed controller tracks a flexible load to the desired reference position as fast as possible and without awkward oscillation. The control method is based on an adaptive backstepping algo-rithm whose stability is ensured by the Lyapunov stability theorem. The unknown parameters of the controller were estimated by means of a differential evolution algorithm. The needed states of the system that are used by controller are estimated by using the Kalman filter. The proposed controller is implemented and tested in a linear motor test drive and responses are presented.
    Proceedings of the Institution of Mechanical Engineers Part I Journal of Systems and Control Engineering 02/2011; 226(2). · 0.78 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: A compact isotope ratio laser spectrometry (IRLS) instrument was developed for simultaneous measurements of the D/H, 18O/16O and 17O/16O isotope ratios in water by laser absorption spectroscopy at 2.73 μm. Special attention is paid to the spectral data processing and implementation of a Kalman adaptive filtering to improve the measurement precision. Reduction of up to 3-fold in standard deviation in isotope ratio determination was obtained by the use of a Fourier filtering to remove undulation structure from spectrum baseline. Application of Kalman filtering enables isotope ratio measurement at 1 s time intervals with a precision (<1‰) better than that obtained by conventional 30 s averaging, while maintaining a fast system response. The implementation of the filter is described in detail and its effects on the accuracy and the precision of the isotope ratio measurements are investigated.
    Sensors 05/2014; 14(5):9027-45. · 2.05 Impact Factor

Full-text (2 Sources)

Available from
May 31, 2014