Dielectric Properties of Agricultural Materials and Their Applications This pageintentionallyleftblank Dielectric Properties of Agricultural Materials and Their Applications Stuart O. Nelson U.S. Department of Agriculture Richard B. Russell Agricultural Research Center Athens, GA USA AMSTERDAM(cid:129)BOSTON(cid:129)HEIDELBERG(cid:129)LONDON NEWYORK(cid:129)OXFORD(cid:129)PARIS(cid:129)SANDIEGO SANFRANCISCO(cid:129)SINGAPORE(cid:129)SYDNEY(cid:129)TOKYO AcademicPressisanimprintofElsevier AcademicPressisanimprintofElsevier 32JamestownRoad,LondonNW17BY,UK 525BStreet,Suite1800,SanDiego,CA92101-4495,USA 225WymanStreet,Waltham,MA02451,USA TheBoulevard,LangfordLane,Kidlington,OxfordOX51GB,UK r2015ElsevierInc.Allrightsreserved. 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This page intentionallyleftblank Contents Foreword.............................................................................................................................................xiii Preface.................................................................................................................................................xv Acknowledgments..............................................................................................................................xix CHAPTER 1 Theory and Fundamental Principles..............................................1 1.1 Dielectric Properties ofMaterials..............................................................................1 1.2 Variation ofDielectric Properties..............................................................................3 1.2.1 Frequency Dependence.....................................................................................3 1.2.2 TemperatureDependence.................................................................................6 1.2.3 Density Dependence.........................................................................................6 References...................................................................................................................8 CHAPTER 2 Measurement of Dielectric Properties.........................................11 2.1 General Principles.....................................................................................................11 2.1.1 AudioFrequencies..........................................................................................14 2.1.2 1to 50MHz....................................................................................................15 2.1.3 50to 250MHz................................................................................................20 2.1.4 200to 500MHz..............................................................................................21 2.1.5 Microwave Frequencies..................................................................................22 2.1.6 BroadbandMeasurements..............................................................................26 References.................................................................................................................28 CHAPTER 3 General Agricultural Applications...............................................33 3.1 Dielectric Heating.....................................................................................................33 3.2 Microwave Heating..................................................................................................34 3.3 Basic Differences......................................................................................................35 3.4 Product Quality Sensing...........................................................................................36 3.5 TreatingSeed-Borne Pathogens...............................................................................37 3.5.1 Loose Smut in Barley.....................................................................................37 3.5.2 Bacteria on Alfalfa Seed................................................................................38 References.................................................................................................................39 CHAPTER 4 Insect Control Applications........................................................41 4.1 Stored-GrainInsects.................................................................................................41 4.1.1 Selective Dielectric Heating...........................................................................41 4.1.2 Experimental Findings....................................................................................42 4.1.3 Entomologic Factors.......................................................................................43 4.1.4 Physical Factors..............................................................................................45 4.1.5 Practical Aspects.............................................................................................50 vii viii Contents 4.2 Pecan Insects.............................................................................................................51 4.3 Summary...................................................................................................................53 References.................................................................................................................53 CHAPTER 5 Seed Treatment Applications......................................................57 5.1 BackgroundInformation...........................................................................................57 5.2 Alfalfa Seed Studies.................................................................................................58 5.2.1 Basic Factors...................................................................................................59 5.2.2 Experimental Findings....................................................................................60 5.2.3 Aspectsof Practical Application....................................................................63 5.3 SweetcloverSeed......................................................................................................64 5.4 Other Small-Seeded Legumesand Some Cereals...................................................65 5.5 Vegetable Seed.........................................................................................................65 5.6 Tree Seed..................................................................................................................66 5.6.1 Pine Seed........................................................................................................66 5.6.2 Other Tree andWoody Plant Seeds...............................................................67 5.7 Summary...................................................................................................................68 References.................................................................................................................69 CHAPTER 6 Product Conditioning Applications..............................................73 6.1 BackgroundInformation...........................................................................................73 6.2 Drying of Chopped Alfalfa......................................................................................73 6.3 Improving Nutritional Value of Soybeans...............................................................74 6.4 Quality Maintenance inPecans................................................................................74 References.................................................................................................................76 CHAPTER 7 Grain and Seed Moisture Sensing Applications............................77 7.1 BackgroundInformation...........................................................................................77 7.2 Early History.............................................................................................................77 7.3 DielectricProperties.................................................................................................78 7.4 Moisture ContentSensing........................................................................................83 7.5 Summaryof Grain Moisture Sensing Development................................................88 7.6 Single Kernel orSeed Moisture Sensing.................................................................89 7.6.1 Single-Kernel Grain Moisture Measurements on Corn.................................90 7.6.2 Single Soybean Seed Moisture Measurements..............................................93 7.6.3 MeasuringMoisture Content inSingle Kernels ofPeanuts..........................94 7.6.4 Comparison ofFour Single-Kernel Moisture Sensing Techniquesfor Corn.......................................................................................95 7.6.5 Single Nut andKernel Pecan Moisture Sensing............................................97 7.6.6 Single-Kernel Microwave-Resonator Moisture Sensing...............................99 References...............................................................................................................103 Contents ix CHAPTER 8 Assessment of Soil Treatment for Pest Control........................... 109 8.1 SoilMicroorganisms andNematodes....................................................................109 8.2 SoilTreatment for Weed Control..........................................................................110 8.3 Initial Assessment...................................................................................................111 8.4 Basic Principles......................................................................................................112 8.5 Further Assessment.................................................................................................113 8.5.1 Attenuation....................................................................................................113 8.5.2 Selective Heating..........................................................................................115 8.5.3 Soil Insect and Nematode Treatment...........................................................117 8.6 Discussion...............................................................................................................118 8.7 Conclusions.............................................................................................................120 References...............................................................................................................120 CHAPTER 9 Quality Sensing in Fruits and Vegetables .................................. 123 9.1 Background Information.........................................................................................123 9.2 Studieson the Use of Dielectric Properties...........................................................123 9.2.1 Melon Studies...............................................................................................124 9.2.2 Apple Studies................................................................................................125 9.2.3 OnionStudies................................................................................................126 9.2.4 Sensing the Moisture Contentof Dates.......................................................127 References...............................................................................................................129 CHAPTER 10 Mining Applications............................................................... 131 10.1 BackgroundInformation—Coal...........................................................................131 10.2 DielectricProperties Measurements on Coal......................................................131 10.3 DielectricHeating of Coal(cid:1)Pyrite Mixtures.......................................................132 10.4 BackgroundInformation—Minerals....................................................................134 10.5 Measurements of the DielectricProperties of Minerals......................................134 10.6 Coal and Limestone Measurements.....................................................................136 10.7 Sensing Pulverized Material Mixture Proportions...............................................142 10.7.1 Principles ofResonantCavityMeasurement..........................................143 10.7.2 MeasuringMixture Proportions..............................................................143 References............................................................................................................145 CHAPTER 11 Dielectric Properties of Selected Food Materials..................... 147 11.1 Measurement of the DielectricProperties of Some Food Materials......................................................................................................147 11.2 Measurements on Hydrocolloid Food Ingredients...............................................159 11.3 DielectricProperties of Chicken Meat for Quality Sensing................................159 References............................................................................................................164
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