| 1. |
- Cerullo, Livia, 1982, et al.
(författare)
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Microwave measurement system for dispersive dielectric properties of densely packed pellets
- 2017
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Ingår i: Measurement: Journal of the International Measurement Confederation. - : Elsevier BV. - 0263-2241. ; 106, s. 179-189
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Tidskriftsartikel (refereegranskat)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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| 2. |
- Cerullo, Livia, 1982, et al.
(författare)
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Microwave Measurements for Metal Vessels
- 2013
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Ingår i: 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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Konferensbidrag (refereegranskat)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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| 3. |
- Nohlert, Johan, 1987, et al.
(författare)
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Global monitoring of fluidized-bed processes by means of microwave cavity resonances
- 2014
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Ingår i: Measurement: Journal of the International Measurement Confederation. - : Elsevier BV. - 0263-2241. ; 55, s. 520-535
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Tidskriftsartikel (refereegranskat)abstract
- We present an electromagnetic measurement system for monitoring of the effective permittivity in closed metal vessels, which are commonly used in the process industry. The measurement system exploits the process vessel as a microwave cavity resonator and the relative change in its complex resonance frequencies is related to the complex effective permittivity inside the vessel. Also, thermal expansion of the process vessel is taken into account and we compensate for its influence on the resonance frequencies by means of a priori information derived from a set of temperature measurements. The sensitivities, that relate the process state to the measured resonance frequencies, are computed by means of a detailed finite element model. The usefulness of the proposed measurement system is successfully demonstrated for a pharmaceutical fluidized-bed process, where the water and solid contents inside the process vessel is of interest.
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| 4. |
- WINGES, JOHAN, 1987, et al.
(författare)
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A Microwave Measurement System for Measurement of Dielectric Properties
- 2014
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Ingår i: AntennEMB, 11-12 March, Göteborg.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- We present a prototype of a microwave measurement system for the estimation of dispersive dielectric properties. The measurement system consists of a metal cavity that features a measurement region in the center formed by the intersection of six rectangular waveguides. The waveguides are terminated by adapters connected to coaxial cables. We exploit the frequency band 2.7-5.1 GHz and a connected network analyzer and switch allows for automatic measurements of the 6-by-6 scattering matrix S.We estimate the complex effective permittivity of densely packed MCC (micro-crystalline-cellulose) pellets over frequency for different moisture contents. This material is used in pharmacutical processes.
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