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Variation of density-independent moisture calibration function c with moisture content and temperature at 8 GHz.
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A dielectric properties-based method is presented for rapid and nondestructive determination of moisture content in almonds independent of bulk density. The method relies on measurements of the dielectric properties at microwave frequencies. The dielectric properties of almonds were measured between 5 and 15 GHz, at 1-GHz increments, for samples wi...
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... the density-independent calibration function for moisture determina- tion is expressed in terms of the dielectric properties, there is need for temperature compensation. For this purpose, density-independent moisture calibration function c is plotted as a function of moisture content and temperature as shown in Figure 6. Moisture content ranged from 4.8% to 16.5% and temperature ranged from 5.2 to 45 C. The data lie in a plane that can be fitted with a regression of the form: ...
Similar publications
A new calibration algorithm is presented for instantaneous and nondestructive determination of moisture contents of in-shell nuts and kernels from measurement of the dielectric properties of in-shell nuts at a single microwave frequency. The new calibration algorithm relies on the use of a density-independent function, expressed in terms of the die...
Citations
... The above problems can be avoided by using dielectric parameters at multiple frequencies. For example, Cao, Lin, Trabelsi et al. [29][30][31] conducted non-destructive testing of the fruit SSC and hardness. The dielectric parameters were tested at multiple frequencies and good results were obtained. ...
This study provides a method for the rapid, non-destructive testing of the internal quality of Korla fragrant pears. The dielectric constant (ε′) and dielectric loss factor (ε″) of pear samples were tested at 100 frequency points (range = 0.1–26.5 GHz) using a vector network analyzer and coaxial probe. The variations in the dielectric parameters of fragrant pears were analyzed. The linear relationships between the dielectric parameters and internal quality were explored. Internal quality prediction models for Korla fragrant pears were built using partial least squares regression (PLSR), support vector regression (SVR) and particle swarm optimization–least squares support vector regression (PSO-LSSVR). The optimal model was then determined. There was a weak correlation between the dielectric parameters and soluble solid content (SSC) under a single frequency. The model based on PLSR and using ε′ as a variable predicted hardness the best, while the model based on PLSR using ε″ as a variable predicted SSC the best. Its R and MSE values were 0.77 and 0.073 in hardness prediction, respectively, and 0.91 and 0.087 in SSC prediction. This study provides a new method for the non-destructive online testing of the internal quality of Korla fragrant pears.
... These four studies represent the most relevant documentation of attempts to quantify the impact of naturally occurring VSW on microwave backscatter within forested environments. In contrast, the literature on microwave detection of the dielectric properties of vegetation and how moisture affects them, in relation to crop species and irrigation, is vast [27][28][29][30][31][32][33]. In light of this gap in silvicultural research, the authors believe there is a need to expand our collective understanding of the impact of VSW on forest canopies due to the growing importance of monitoring forest health and resilience to drought. ...
This study addresses the escalating challenges posed by forest drought and wildfires, emphasizing the critical need to monitor forest conditions to mitigate associated risks. While traditional optical sensors have proven valuable for vegetation surface water (VSW) assessment, their limitations in regions with persistent cloud cover prompt an exploration of the alternatives. The study advocates the efficacy of Synthetic Aperture Radar (SAR) systems, known for their cloud-penetrating capabilities and sensitivity to changes in dielectric properties. Leveraging Sentinel-1 C-band dual polarization SAR data, the research investigates the impact of Vegetation Surface Water (VSW) on backscatter coefficients in a temperate coniferous forest through the application of generalized linear models. Despite the challenges posed by precipitation and canopy characteristics, the study unveils detectable modulation in backscatter, particularly in VH polarization, indicating the potential of SAR-based methods in forest monitoring. The occurrence of rain on the day of Sentinel-1 image acquisition, and therefore the presence of VSW, triggers an increase of 0.35 dB in VV backscatter, and an increase of 0.45 dB in VH backscatter. The findings underscore the importance of considering surface water content in radar backscatter analyses for accurate biomass estimations and change detection, suggesting avenues for future research and potential correction mechanisms.
... Thanks to these methods, measurements are made especially for the storage of fruits, 5,8 and the heating/drying processes of plants. 9,10 Studies are also carried out to remove harmful insects from alfalfa by microwave heating/drying processes, and some researchers focus on wheat and corn, which are grain products. 1,3 Various models are developed by examining the stems and leaves of plants in terms of dielectric parameters. 2 The dielectric parameters of corn and tomato leaves are measured both in live, 3,11 and by detaching them from the branch and the water needs of these leaves are estimated in real-time. ...
... with six inputs and two outputs (MAE), root mean squared error (RMSE), mean absolute percentage error (MAPE), and R-squared (R 2 ) that are given in Equations (7) to (10). ...
In this paper, dielectric properties of citrus leaves are predicted with long short‐term memory (LSTM) which is one of the well‐known deep neural network (DNN) models and real‐time measurements for any moisture content (MC) values in the range of 4.90 to 7.05 GHz at a fixed temperature of 24°C for microwave applications, as a novelty. Firstly, S‐parameters of samples are measured with WR‐159 waveguide and Waveguide Transmission Line Method. In addition, the MCs of samples depending on their weights are calculated. Thus, the dataset depending on various MC and frequency is obtained with the measurement results to both training and testing the DNN model. Secondly, a total of 4000 datasets are obtained, 80% of which is used for training, and 20% for testing. The proposed DNN model consists of four inputs (f, MC, S11, and S21) and two outputs (ε′ and ε″). Finally, the dielectric parameters for the desired MC and f are displayed with the graphical user interface in real‐time. Success criteria for the prediction such as mean absolute error, root mean squared error, mean absolute percentage error, and R‐squared are calculated. The results indicated that there is good agreement between the measured and predicted ones. R‐squared are calculated as 0.962 and 0.968 for ε′ and ε″, respectively.
... Electrical properties of grain, guava, mameyi, sapote, prickly pears, nopal, corn seeds, rapeseed, almonds, dates, hazelnuts, and nuts such as dielectric constant is also utilize to determine moisture content using the method called capacitance technique [14][15] [16][17] [18][19] [20]. Conveniently, instantaneous measurement of moisture content using free space transmission were also apply using the phase shift, attenuation, and dielectric properties of the grains, almond kernels, peanut kernels, jamun, and fresh vegetables [21] [31]. ...
... Besides enabling under storage monitoring of agricultural products, the measurements are made for the storage of the agricultural products (Nelson 2006;Nelson 1991). Microwave power is also used in the heating and drying processes of plant (Trabelsi et al. 2016;Kamaruddin et al. 2017). Through these heating/drying processes, harmful insects are removed from alfalfa. ...
In order to exploit the use of remote sensing, microwave heating/drying and water stress in the agricultural sector, it is necessary to determine the dielectric properties of plant materials (branches, leaves, roots, fruits). In this way, the yield and quality of
agricultural products can be increased. In this study, dielectric parameters of the sweet cherry and sour cherry leaves are measured by waveguide transmission line Method.
The dielectric properties of the leaves (varying moisture content) are measured over a frequency ranging from (3.30-7.05GHz) using WR229 (3.30-4.90GHz) and WR159 (4.90-7.05GHz) waveguide structures. A novel curve fitting technique is used to characterize dielectric properties of sweet cherry leaves. In order to verify the accuracy
of the model the data obtained using this methodology is compared with measurement data of sour cherry leaves belonging to the same family. The determination coefficient R 2 of the model for WR229 and WR159 are 0.996 and 0.998, respectively. Similarly, the Root Mean Square Error (RMSE) values of the model for WR229 and WR159 are
0.852 and 0.236, respectively.
... İlk çalışmalarda genelde kapasitif ölçme tekniği kullanılarak bitkilerin dielektrik özellikleri belirlenirken [7], sonraki çalışmalarda daha geniş frekans aralıklarında mikrodalga ölçüm yöntemleri kullanılarak birçok ürünün dielektrik parametreleri ortaya konulmuştur. Bu yöntemler sayesinde, özellikle meyvelerin depolanmasına yönelik ölçümler yapılmış olup [5,8], bitkilerin ısıtma/kurutma süreçlerinde de bu yöntemlerin kullanılmıştır [9,10]. Mikrodalga ısıtma/kurutma işlemleri ile yoncalardan zararlı böcekleri arındırmaya yönelik çalışmalar da yapılmıştır. ...
Today, in the agricultural sector, the use of remote sensing and automation systems is increased to increase the yield and quality of the product. One of the main determinant parameters in the technologies used in microwave heating/drying and remote monitoring/control an application is the dielectric properties of plants. Therefore, it is important to determine the dielectric characteristics of plant materials for proper operation of the systems to be used in these applications. In this study, dielectric parameters of the peach and quince leaves produced in Isparta region are measured by Waveguide Transmission Line Method. Measurements are conducted between 3.30-4.90 GHz (for WR229 waveguide) and the dielectric characteristics of the leaves are examined depending on the moisture content and frequency. A new model with a curve fitting method based on frequency and moisture content (MC) is proposed used dielectric measurement data of peach leaves. This model is compared with the dielectric measurement results of quince leaves which belong to the same family with peach type to see the accuracy of the proposed model is tested. To obtain the performance of the model, the coefficient of regression R2 and Mean Square Root of Errors (RMSE) are obtained as 0.995 and 0.755, respectively.
... Bu yöntemlerle bitkisel ürünler, hasat sonrası sağlıklı ve uzun süreli depolanabilirler. Ayrıca bu ürünlerin, zararlı haşerattan korunmaları da sağlanır (Trabelsi, 2016;Shrestha, 2011). Günümüzde, soğurucu malzeme olarak kullanılan polimer tabanlı materyallerin zamanla soğurma özelliğini kaybetmesi ve sağlık/çevre açısından riskler barındırması, organik bitkisel malzemelerden soğurucu malzemesi üretme çalışmalarını hızlandırmıştır. ...
... Bitkisel malzemelerle ilgili tüm çalışmalarda temel motivasyon, bu malzemelerin dielektrik özelliklerinin belirlenmesidir. Yapılan çalışmalarda bu malzemelerinin dielektrik geçirgenliğinin, büyük oranda bitkinin içerdiği su miktarına bağlı olduğu görülmüştür (Trabelsi, 2016;Kraszewski ve Nelson, 2004). Ayrıca ortaya konulan modellerde bitkisel malzemelerin (yaprak, dal, meyve, vb.) ortalama dielektrik geçirgenliğinde yaprakların daha baskın olduğu gözlenmiştir (Chuah, 1997) Kayıplı ortamlarda kompleks dielektrik sabitinin reel kısmı (ε'), EM enerjinin malzeme içerisinde ne kadar depo edildiğini belirlerken, sanal kısmı ise EM yayılım hızını, zayıflamayı ve iletim parametrelerini belirler. ...
Gelişen teknolojiyle birlikte tarımsal ürünlerdeki uygulamalar gün geçtikçe yaygınlaşmaktadır. Bu uygulamalarda temel belirleyici parametre, bitkisel malzemenin dielektrik özelliğinin belirlenmesidir. Çünkü malzemeye nüfuz eden elektromanyetik (EM) dalganın malzemeyle nasıl etkileşeceği dielektrik özelliklerine de bağlıdır. Üretimde verim ve kalitenin artmasını sağlayan uzaktan algılama (UA) ile kurutma ve ısıtma teknolojilerinin etkin çalışabilmesi, malzemenin dielektrik karakteristiğiyle ilişkilidir. Bu çalışmada, Türkiye’de çok yaygın olarak üretimi yapılan kayısı ve erik ağaçlarının yapraklarının dielektrik parametreleri iletim hattı yöntemi kullanılarak ölçülmüştür. Ölçümler 3,30-4,90 GHz arasında (WR229 dalga kılavuzu için) yapılmış ve nem oranı ve frekansa bağlı kayısı ve erik yapraklarının dielektrik karakteristikleri incelenmiştir. Kayısı yapraklarının dielektrik ölçüm verilerini kullanarak frekans ve nem oranına bağlı, eğri uydurma yöntemiyle yeni bir model önerilmiştir. Bu model, kayısı türüyle aynı aileden olan erik yaprağının dielektrik ölçüm sonuçlarıyla karşılaştırılarak önerilen modelin doğruluğu test edilmiştir. Modelin performansını görmek için determinasyon katsayısı R2 ve Hataların Ortalama Kare Kökü (RMSE) değerleri sırasıyla 0.996 ve 0.653 olarak elde edilmiştir.
... Processing of peanuts requires rapid testing methods for accurate and efficient determination of physical properties such as moisture content. Dielectric properties have been proven useful in the determination of physical properties of cereal grain, oilseed, nuts, and biomass (Boldor et al., 2004;Ellison et al., 2017;Kaatze and Hübner, 2010;Trabelsi et al., 2016b;Trabelsi and Nelson, 2016). ...
Highlights
Real-time, free-space transmission measurements of relative complex permittivity in unshelled peanuts during drying
Dynamic application: temperature, density and moisture content changing during drying
Three density-independent calibration functions evaluated for accuracy in real-time moisture content determination
Real-time moisture content determination with standard error of performance ( SEP ) = 0.55% moisture content for all calibration functions
Calibration function most commonly used with microwave moisture sensor was determined to be most accurate; SEP = 0.448% moisture content
Abstract . A microwave moisture sensor, developed within USDA ARS, has been used to determine moisture content in unshelled peanuts during drying. Relative complex permittivities of the peanuts obtained from free-space transmission measurements at 5.8 GHz are used for the moisture determination. Due to variations in density caused by drying, it is advantageous to estimate moisture content independent of bulk density. Therefore, moisture content was estimated with three density-independent calibration functions to assess which one provided optimal accuracy. One of the functions is based on the measured attenuation and phase shift, and the other two are permittivity based (one of which is commonly used with the microwave moisture sensor). The sensor was calibrated for peanut pod moisture content determination over a temperature range of 10°C to 40°C and a moisture content range of 6.5% to 19% wet basis (w.b.). Statistical analysis showed high coefficients of determination (r2), = 0.97 for the calibration with each function. Peanut pod moisture content was determined with the sensor in real-time as peanuts dried, and estimated moisture content was compared to the reference oven drying method. While the standard error of performance (SEP) for the three functions was = 0.55% moisture content, the calibration function most commonly used with the microwave sensor was observed to be the most accurate (SEP = 0.448% moisture content). Microwave sensing is a viable solution for nondestructive, real-time determination of moisture content in peanuts in dynamic situations such as drying. Keywords: Complex permittivity, Dielectric properties, Free-space measurements, Microwave sensing, Moisture content, Peanut drying.
... In agriculture, moisture content is used in preharvest and postharvest operations to assess the quality of a given commodity, its fair value, and safe storage conditions [4], [5]. For instance, moisture content is used in the grading of peanuts [6], [7], almonds [8], and other in-shell nuts. It is also used to determine the shelf life of these commodities and to monitor the drying process [9]. ...
... While this function is independent of bulk density, there is still need for correction for temperature [15], [16]. The densityindependent ψ was applied successfully to determine moisture content in cereal grains, oil seeds, nuts, and other granular and particulate materials [6], [8], [17], [18]. ...
A new calibration algorithm is presented for instantaneous and nondestructive determination of moisture contents of in-shell nuts and kernels from measurement of the dielectric properties of in-shell nuts at a single microwave frequency. The new calibration algorithm relies on the use of a density-independent function, expressed in terms of the dielectric properties, and the existence of a direct relationship between the in-shell nut oven moisture content and kernel oven moisture content. Results of measurement by using a microwave moisture sensor operating at 5.8 GHz are presented, and kernel moisture calibration equations are established for peanuts and almonds.
... Thanks to this scattering and absorption, the studies that include the dielectric properties of the vegetation cover and the studies that evaluate the loss factor are limited. 4 Therefore, there is no general model measuring the dielectric constant accurately according to the physical characteristics of the plant. In literature, environments of vegetative materials on dielectric parameters are studied. ...
Remote sensing technology is useful for detecting agricultural and fruit regions. In this way, the world map can be determined in terms of the vegetation canopy. Contrary to this case, the vegetation canopies can also be used in areas such as intelligence and military regions that are required to be hidden and invisible. The use of microwave remote sensing technology is more sensitive to radiation than other methods, so it allows us to have knowledge about the volumetric information of the target object. However, this method is based on obtaining the dielectric properties of the samples. The aim of this paper is to examine the effect of the moisture content on relative dielectric constant and dielectric loss of banana leaves at X‐band as a novelty. In this study, transmission line technique is used to measure dielectric properties of the samples (banana leaves) in 8.2 to 12.4 GHz. The initial natural moisture content of the fresh banana leaves before drying is calculated to be approximately 82%. The moisture content of the banana leaves is dried from about 82% to 40%. As a result, the relative dielectric constant of it decreases with increasing frequency. In addition, increased moisture content increases both real and imaginary parts of dielectric constant. Correspondingly, unlike literature, a model that calculates the relative dielectric constant and dielectric loss value of the banana leaves is obtained. Root mean square error (RMSE) and R‐squared (R2) are calculated to see regression performance of the proposed model.
