Density Independent and Temperature Compensated Moisture Prediction Model for Agricultural Products Using Impedance Analyzer: A Review

Agricultural products play an essential role in stabilizing the country economy. Third largest sector of Indian economy is agricultural products. In agricultural products the important factor for post harvesting, processing, storage and transport, is moisture, which affect their quality. In modern agriculture fast, non-destructive and reliable sensing technique for determination of moisture content in agricultural crops is required to prevent the losses and to improve efficiency of production. Various techniques are available for moisture sensing in agricultural products and better results have been achieved with use for these techniques. The performance of developed method for moisture sensing is comparable with that of commercial moisture meter. The most reliable solution for measuring the moisture content of agricultural products and non-destructive method is use of bulk density dielectric function. This paper reviews the area of moisture determination methods for various agricultural products and summarizing the various electrical methods for moisture determination

Microwave density – independent permittivity functions as soybean seeds’ moisture calibrators: A new approach

 Priyanka Das, Zeeshan Ahmad, H. N. Singh, Ashutosh Prasad(University Dept. of Physics, Tilkamanjhi Bhagalpur University, Bhagalpur – 812007, India) Abstract: The present work makes use of data for real part of microwave complex permittivity as function of moisture content measured at 2.45 GHz and 24℃, as extracted from the literature.  The data were individually converted to those for solid materials using seven independent mixture equations for effective permittivity of random media.  Moisture dependent quadratic models, as developed by the present group, were used to evaluate the dielectric loss factor of soybean seeds.  Using these data, a number of density – independent permittivity functions were evaluated and plotted as a function of moisture content of the samples.  Second and third order polynomial and first order exponential growth type of curve fittings with these data have been tried and their performances are reported.  Coefficients of determination (r2) approaching unity (»0.989 – 0.999) and very small Standard Deviation (SD) up to 3.45×10–4 for these models possess good acceptability.  The regularity in the nature of these variations revealed the usefulness of these densities – independent permittivity functions as indicators/calibrators of moisture content of soybean seeds.  Keeping in view the fact that moisture content of grains and seeds is an important factor determining quality and affecting the storage, transportation, and milling of grains and seeds, the work has the potentiality of its practical applications.Keywords: microwave complex permittivity, density-independent permittivity functions, soybean, Dielectric Mixture equations, moisture meters, least–squares fit analysis Citation: Priyanka Das, Zeeshan Ahmad, H.N.Singh, Ashutosh Prasad.  Microwave density – independent permittivity functions as soybean seeds’ moisture calibrators: A new approach.  Agric Eng Int: CIGR Journal, 2010, 12(3): 107-114. &nbsp

Frequency, moisture content, bulk density and hybrid effects on grain sorghum dielectric properties

The interest in the dielectric properties of grains has been increasing over the years due to their potential utilization in advanced technologies such as the density-independent on-line estimation of moisture content in automatic control processes in grain drying operations. A capacitive sensor was used with a LCR meter to obtain a better understanding of the variation of relative permittivity and dielectric loss factor of four hybrids of grain sorghum in the frequency range from 75 kHz to 5 MHz, at 23°C and 62% relative humidity. Curves that are presented illustrate the variation of these dielectric properties on moisture content (7% to 23% w.b.), bulk density (575 to 819 kg/m3) and hybrid. The obtained results should provide a firm basis for future accurate, fast and non-destructive determination of grain moisture content and bulk density in automated industrial drying and storage processes

Dielectric Spectroscopy in Biomaterials: Agrophysics

Being dependent on temperature and frequency, dielectric properties are related to various types of food. Predicting multiple physical characteristics of agri-food products has been the main objective of non-destructive assessment possibilities executed in many studies on horticultural products and food materials. This review manipulates the basic fundamentals of dielectric properties with their concepts and principles. The different factors affecting the behavior of dielectric properties have been dissected, and applications executed on different products seeking the characterization of a diversity of chemical and physical properties are all pointed out and referenced with their conclusions. Throughout the review, a detailed description of the various adopted measurement techniques and the mostly popular equipment are presented. This compiled review serves in coming out with an updated reference for the dielectric properties of spectroscopy that are applied in the agrophysics fiel

Inline 3D volumetric measurement of moisture content in rice using regression-based ML of RF tomographic imaging

The moisture content of stored rice is dependent on the surrounding and environmental factors which in turn affect the quality and economic value of the grains. Therefore, the moisture content of grains needs to be measured frequently to ensure that optimum conditions that preserve their quality are maintained. The current state of the art for moisture measurement of rice in a silo is based on grab sampling or relies on single rod sensors placed randomly into the grain. The sensors that are currently used are very localized and are, therefore, unable to provide continuous measurement of the moisture distribution in the silo. To the authors’ knowledge, there is no commercially available 3D volumetric measurement system for rice moisture content in a silo. Hence, this paper presents results of work carried out using low-cost wireless devices that can be placed around the silo to measure changes in the moisture content of rice. This paper proposes a novel technique based on radio frequency tomographic imaging using low-cost wireless devices and regression-based machine learning to provide contactless non-destructive 3D volumetric moisture content distribution in stored rice grain. This proposed technique can detect multiple levels of localized moisture distributions in the silo with accuracies greater than or equal to 83.7%, depending on the size and shape of the sample under test. Unlike other approaches proposed in open literature or employed in the sector, the proposed system can be deployed to provide continuous monitoring of the moisture distribution in silos

Electromagnetic heating for industrial kilning of malt: a feasibility study

Industrial malting operations use ~800kWh/t of energy to produce the heat required to kiln malt. Electromagnetic heating technologies are suggested as a way to potentially improve the energy efficiency of the kilning processing. In this work, the potential for using electromagnetic heating to dry malt to commercially acceptable moisture levels, whilst preserving the activity of enzymes critical for downstream brewing processes is investigated. The 2450 MHz bulk dielectric properties of malt at moisture contents consistent with those occurring at different points in the kilning process are evaluated; 12% is shown to be a critical moisture level below which drying becomes more energy intensive. Calculated penetration depths of electromagnetic energy in malt at radio frequency are 100 fold higher than at microwave frequencies, showing a significant advantage for commercial scale batch processing. The moisture contents and alpha and beta amylase activity of malt subjected to RF heating at different temperatures, treatment times and RF energy inputs in the intermediate and bound water drying regions were determined. It is shown for the first time that whilst significantly reduced process times are attainable, significant energy efficiency improvements compared to conventional kilning can only be achieved at higher product temperatures and thus at the expense of enzyme survival. It is suggested that RF heating may be feasible where higher bulk temperatures are not critical for downstream use of the material or when used in hybrid systems

Microwave Indices from Active and Passive Sensors for Remote Sensing Applications

Past research has comprehensively assessed the capabilities of satellite sensors operating at microwave frequencies, both active (SAR, scatterometers) and passive (radiometers), for the remote sensing of Earth’s surface. Besides brightness temperature and backscattering coefficient, microwave indices, defined as a combination of data collected at different frequencies and polarizations, revealed a good sensitivity to hydrological cycle parameters such as surface soil moisture, vegetation water content, and snow depth and its water equivalent. The differences between microwave backscattering and emission at more frequencies and polarizations have been well established in relation to these parameters, enabling operational retrieval algorithms based on microwave indices to be developed. This Special Issue aims at providing an overview of microwave signal capabilities in estimating the main land parameters of the hydrological cycle, e.g., soil moisture, vegetation water content, and snow water equivalent, on both local and global scales, with a particular focus on the applications of microwave indices