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| 2. |
- Cerullo, Livia, 1982, et al.
(author)
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Concurrent estimation of space and frequency variation for dielectrics: a microwave tomography system for process sensing applications
- 2011
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In: Proceedings of the 9th International Conference on Electromagnetic Wave Interaction with Water and Moist Substances, Kansas City, MO USA, May 31 - June 3, 2011. - 9781629934556 ; , s. 177-184
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Conference paper (peer-reviewed)abstract
- In many powder processing operations, the effective complex permittivity of the material under processing yields important information concerning the state of the process. This complex permittivity varies in general with respect to both space and frequency. For an accurate estimation of the process material parameters, it is important to be able to incorporate these dependencies in the estimation algorithm. Here, we present a rather general type of parameterization that is tailored for this type of situation. The parameterization is described in terms of a parameterization mesh, which makes it feasible to refine the computational mesh without influencing the number of degrees of freedom in the estimation problem. A test case demonstrates that our approach can yield accurate reconstructions.
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| 3. |
- Cerullo, Livia, 1982, et al.
(author)
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Inverse scattering for a closed cavity equipped with microwave antenna sensors
- 2012
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In: AntennEMB, 5-8 March, Stockholm.
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Conference paper (other academic/artistic)abstract
- Pharmaceutical processes are often hosted by completely closed vessels that are difficult of access by means of measurement equipment. In particular, it is challenging to assess the interior or global process state with sensors placed on the vessel enclosing the process. This information about the process would allow for a better process monitoring and control. Here, a novel application of microwave sensing for process tomography is presented.
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| 4. |
- Cerullo, Livia, 1982, et al.
(author)
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Microwave measurement system for dispersive dielectric properties of densely packed pellets
- 2017
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In: Measurement: Journal of the International Measurement Confederation. - : Elsevier BV. - 0263-2241. ; 106, s. 179-189
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Journal article (peer-reviewed)abstract
- We present a microwave measurement system that is intended for the estimation of the dispersive dielectric properties for densely packed pellets. In particular, we estimate the Debye parameters for the effective permittivity of a mixture of air and densely packed moist microcrystalline cellulose pellets for the frequency band 2.7–5.1 GHz. The Debye parameters are estimated by means of minimizing the misfit between the measured scattering parameters and the corresponding computed response given a model of the measurement system. This minimization is performed by means of a nonlinear iterative optimization procedure, which is supported by continuum sensitivities, and the optimum is found in 10–60 iterations for the cases presented in this article. We find that increasing moisture content yields an increase in the static permittivity and a decrease in the relaxation time.
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| 5. |
- Cerullo, Livia, 1982, et al.
(author)
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Microwave Measurements for Metal Vessels
- 2013
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In: 7th European Conference on Antennas and Propagation, EuCAP 2013, Gothenburg, Sweden, 8-12 April 2013. - 2164-3342. - 9781467321877 ; , s. 3869 - 3873
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Conference paper (peer-reviewed)abstract
- We present two different measurement techniques intended for closed metal vessels, where the objective is to measure the permittivity inside the metal vessel. This problem is relevant for many applications found in e.g. process industry. The first approach exploits the measurement of resonance frequencies, where the metal vessel is used as a microwave resonator. In the second approach, we let the boundary of the metal vessel be equipped with aperture antennas, where the aperture antennas are implemented in terms of rectangular waveguides. The waveguide apertures loads the cavity significantly and we exploit the scattering matrix parameters for the solution of the inverse problem.
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| 6. |
- Garcia Wernersson, Joakim, et al.
(author)
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Non-destructive density measurements of pharmaceutical products by THz imaging
- 2016
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In: International Conference on Infrared, Millimeter, and Terahertz Waves, IRMMW-THz. - 2162-2027 .- 2162-2035. - 9781467384858 ; 2016-November, s. Art. no 7758615-
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Conference paper (peer-reviewed)abstract
- In this paper, measurements with a THz imaging system at 346 GHz together with electromagnetic simulations have demonstrated the capability of THz sensing for the non-destructive density determination of intermediate products in the pharmaceutical industry. The results confirm the ability of THz imaging to detect density changes in pharmaceutical samples by measuring the phase variation of the wave transmitted through the sample.
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| 7. |
- Gradinarsky, Lubomir, 1970, et al.
(author)
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A method for detection of powder materials in metallic hollow structures using microwaves
- 2008
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In: Measurement: Journal of the International Measurement Confederation. - : Elsevier BV. - 0263-2241. ; 41:6, s. 637-646
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Journal article (peer-reviewed)abstract
- This paper presents a method for detection of the presence of small amounts of solids (powders, granules, etc.) inside metallic structures such as process vessels and containers. The method is based on propagation of microwave electromagnetic (EM) energy inside the structures and analysing the complex reflection coefficient Gamma represented by the scattering parameter S-11. 3D EM simulations were used to predict the behaviour of S for structures of rectangular, circular, and conical shapes, contaminated with materials with weak dielectric properties. The suggested method sensitivity and the effects of the material size and its distribution were assessed and results presented of comparisons of simulations and measurements. This paper demonstrates the ability to detect very low levels of contamination, e.g. of the order of 0.01-0.03 parts of a reference vessel's volume of one (e.g. length = 1 cm, width = 0.5 cm, and height = 2 cm) for materials with weak dielectric properties. This sensitivity is even better in terms of volume ratio (contamination/vessel's volume) for structures with bigger volumes and contaminants with stronger dielectric properties e.g. wet powders. The method is fully scalable for vessels with different sizes. Therefore industrial application of the method to physical processing of pharmaceutics, food, agriculture and others is envisioned. (C) 2007 Elsevier Ltd. All rights reserved.
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| 8. |
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| 9. |
- Gradinarsky, Lubomir, 1970, et al.
(author)
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Horizontal gradients in the wet path delay derived from four years of microwave radiometer data
- 2000
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In: Geophysical Research Letters. - 1944-8007 .- 0094-8276. ; 27:16, s. 2521-2524
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Journal article (peer-reviewed)abstract
- We have analyzed four years of inferred wet path delay data from a microwave radiometer operating at 21.0 and 31.4 GHz. We have applied a four parameter gradient model to the wet delays, using different lengths of the time series for the gradient estimation. The mean gradient, averaged over 15 to 1440 minutes, varies between 0.9 and 0.4 mm End has a preferred direction towards the north-east. Increasing the averaging time causes the estimated gradient to decrease. The 15 minutes mean gradient is 1.3 mm for the summer months and 0.7 mm for the winter months. Structure function results are also presented.
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