Fruit and Vegetable Quality Assessment via Dielectric Sensing

Khaled, Dalia El; Novas, Nuria; Gázquez, José Antonio; Manzano‐Agugliaro, Francisco

doi:10.3390/s150715363

Cited by 84 publications

(57 citation statements)

References 90 publications

(112 reference statements)

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“…The variations in reflected voltage, V r of tea leaves bulk with the percentage of m.c at various operating frequencies, respectively, are plotted in Figure 5a-e. As expected, the reflected voltage, V r of tea leaves increases exponentially with m.c, since relative permittivity, ε r of agricultural product normally increases exponentially with its m.c [20] at higher operating frequencies. From Figure 5, we found that the measurement frequency at 1.529 GHz is able to provide stable and sensitive measurement with respect to m.c of the all tea leaves.…”

Section: Resultssupporting

confidence: 74%

Monitoring Moisture Content for Various Kind of Tea Leaves in Drying Processes Using RF Reflectometer-Sensor System

et al. 2018

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This paper presents tea leaves moisture monitoring system based on RF reflectometry techniques. The system was divided into two parts which are the sensor and reflectometer parts. The large coaxial probe was used as a sensor for the system. The reflectometer part plays a role as signal generator and also data acquisition. The reflectometer-sensor system was operated with a graphical user interface at 1.529 GHz at room temperature. The system was able to measure the moisture content of tea leaves ranging 0% m.c to 50% m.c on a wet basis. In this study, up to five kinds of tea leaves bulk were tested. The mean of absolute errors in the moisture measurement for tea leaves was ±2.

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Section: Resultssupporting

confidence: 74%

Monitoring Moisture Content for Various Kind of Tea Leaves in Drying Processes Using RF Reflectometer-Sensor System

et al. 2018

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“…The complex permittivity measures the ability of a material to absorb and store potential electrical energy and is composed of a real permittivity (ϵ′) part, that describes the ability of a material to store energy when it is subjected to an electric field and influences the electric field distribution and the phase of waves travelling through the material, and an imaginary permittivity (ϵ′′) part, that influences both energy absorption and attenuation and describes the ability to dissipate energy in response to an applied electric field through various polarization mechanisms that commonly result in heat generation . Loss tangent

(t a n δ = ϵ^{^{'}^{'}} / ϵ^{^{'}})

indicates the ability of the material to transform energy into heat.…”

Section: Electromagnetic Shielding Materialsmentioning

confidence: 99%

Electromagnetic Shielding Materials in GHz Range

González

Pozuelo

Baselga

2018

The Chemical Record

126

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The state-of-the art in the design and the manufacture methods of the different electromagnetic shielding materials has been reviewed. This topic has become a mainstream field of research because of the electromagnetic pollution generated by telecommunication technology development. The review is centred in absorbent materials and shows a general overview of how the absorption properties of such composites can be tailored through changes in geometry, composition, morphology, and the filler particles content. Although different types of materials are explained, the text is mainly focused on carbon materials such as graphene and carbon nanotubes. In this way, the importance of the dispersion of the conductive fillers in different polymer matrices is discussed. In addition, an extensive study on new complex architectures such as foam-based materials is presented. Finally, the combination of carbon fillers with other constituents such as metallic nanoparticles is mentioned. In all these studies, the efficiency of the composites as absorbent or reflective of electromagnetic radiation is discussed.

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“…The interaction of electromagnetic waves with matter is sensitive to various physical and chemical parameters ([1,2]). Hence, high frequency (radio and microwave) electromagnetic methods (HF-EM) present a strong potential for quantitative estimation for water content for porous media in geoenvironmental engineering [3].…”

Section: Introductionmentioning

confidence: 99%

Error Analysis of Clay-Rock Water Content Estimation with Broadband High-Frequency Electromagnetic Sensors—Air Gap Effect

Boré

Wagner

Lesoille

et al. 2016

Sensors

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Broadband electromagnetic frequency or time domain sensor techniques present high potential for quantitative water content monitoring in porous media. Prior to in situ application, the impact of the relationship between the broadband electromagnetic properties of the porous material (clay-rock) and the water content on the frequency or time domain sensor response is required. For this purpose, dielectric properties of intact clay rock samples experimental determined in the frequency range from 1 MHz to 10 GHz were used as input data in 3-D numerical frequency domain finite element field calculations to model the one port broadband frequency or time domain transfer function for a three rods based sensor embedded in the clay-rock. The sensor response in terms of the reflection factor was analyzed in time domain with classical travel time analysis in combination with an empirical model according to Topp equation, as well as the theoretical Lichtenecker and Rother model (LRM) to estimate the volumetric water content. The mixture equation considering the appropriate porosity of the investigated material provide a practical and efficient approach for water content estimation based on classical travel time analysis with the onset-method. The inflection method is not recommended for water content estimation in electrical dispersive and absorptive material. Moreover, the results clearly indicate that effects due to coupling of the sensor to the material cannot be neglected. Coupling problems caused by an air gap lead to dramatic effects on water content estimation, even for submillimeter gaps. Thus, the quantitative determination of the in situ water content requires careful sensor installation in order to reach a perfect probe clay rock coupling.

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Fruit and Vegetable Quality Assessment via Dielectric Sensing

Cited by 84 publications

References 90 publications

Monitoring Moisture Content for Various Kind of Tea Leaves in Drying Processes Using RF Reflectometer-Sensor System

Monitoring Moisture Content for Various Kind of Tea Leaves in Drying Processes Using RF Reflectometer-Sensor System

Electromagnetic Shielding Materials in GHz Range

Error Analysis of Clay-Rock Water Content Estimation with Broadband High-Frequency Electromagnetic Sensors—Air Gap Effect

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