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100. Whalley W.R.: Considerations on the use of time-domain reflectometry (TDR) for measuring soil water content. Journal of Soil Science. 44:1-9. 1993. 101. White, I., Zegelin S.J., Topp G.C., Fish A.: Effect of bulk electrical conductivity on TDR measurement of water content in porous media. Special Publication SP 19- 94. Symposium and Workshop on TDR in Environmental, Infrastructure, and Mining Ap-plications. Northwestern University, Evanston, USA. 1994. 102. Whitney M., Gardner F., Briggs L.J.: An electrical method of determining the moisture content of arable soils. U.S. Dept. Agr., Div. Soils, Bull. 6. 1897. 103. Wiczer J.: Connectivity: smart sensors or smart interfaces. ISA 2001 Emerging Technologies Conference, Huston, TX, Sept. 10-13, 2001. 104. Wilczek A., Mazurek W., Skierucha M.: Application of wireless communication in automatic monitoring of temperature in soil profile (in Polish). Acta Agrophysica 93:123-133, 2003. 105. Wright J.M., Or D: Temperature effects on soil bulk dielectric permittivity measured by time domain Reflectometry: Experimental evidence and hypothesis development. Water Res. Res., 35, No.2: 361-369. 1999. 106. Zegelin S.J., White I., Jenkins D.R.: Improved field probes for soil water content and electrical conductivity measurement using Time Domain Reflectometry. Water Res. Res., 25, No.11: 2367-2376. 1989. 143
14. INDEX OF FIGURES Fig. 1. Hardware setup for simultaneous measurement of soil water content and electrical conductivity using Time Domain Reflectometry method .........................................................................16 Fig. 2. Relation between the soil refractive index, n, and its water content, θ, for mineral and organic soil samples as well as their mixtures. A - experimental data, B - regression n(θ). .........................18 Fig. 3. Relations between the refractive index, n = ε , and volumetric water content, θ, and related regression lines......................................20 Fig. 4. Relative refractive index, n = ε , as the function of water content for selected wood types .......................................................................21 Fig. 5. Bulk electrical conductivity, EC a-TDR , of the investigated soil samples obtained using TDR pulse attenuation method accordingly to Eq. (3), versus reference data, EC a-4p , determined using four-electrode reference method................................................23 Fig. 6. Comparison of the bulk electrical conductivity of the investigated soils, EC a-TDR , with the reference data, EC a-4p , after correction accordingly do the polynomial of Fig. 5 .............................................24 Fig. 7. Frequency dispersion of the real part, ε’, and module, k, of the complex dielectric constant of the electrolyte for different conductivities.......................................................................................27 Fig. 8. Frequency dispersion of the real part, ε’, of the complex dielectric constant and the loss angle, δ, for the electrolyte for its various electrical conductivities, EC w ..............................................................29 Fig. 9. The relation n(θ ) for soil samples moistened by KCl solutions of different electrical conductivities, EC w ...............................................32 Fig. 10. TDR interpretation of soil as a tree phases medium in dielectric mixing model α ...................................................................................33 Fig. 11. Determination of the dielectric constant of soil solid phase using extrapolation and three-phase soil dielectric mixing model α. ...........37 Fig. 12. Relation between the soil relative dielectric constant, ε, and soil volumetric water content, θ, for the investigated mineral soils. The solid line represents the empirical model (31) calculated for the average bulk density of the soil samples 1.42 [gcm -3 ]...................38 Fig. 13. Comparison of soil relative dielectric constants of the investigated soil samples measured by TDR method (horizontal axis) and 144
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TDR METHOD FOR THE MEASUREMENT OF W
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PREFACE The importance of water for
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CONTENTS 1. Status of water as an s
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12.2. New prototype version of FOM/
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that stimulate the phenomena and pr
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The solution to the problem of elec
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3. ELECTRICAL MEASUREMENTS METHODS
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v = c 1 2L = = ( θ ) n ∆t ε (2)
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The TDR probe consists of two waveg
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ε a =1 and φ=0.5 the Eq. (10) has
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The experiment description is given
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Results obtained with the discussed
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Notice that at C s = 0, ie when dis
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water orientation polarization [s],
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Fig. 8. Frequency dispersion of the
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The measurements were performed in
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5. EVALUATION OF DIELECTRIC MIXING
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ε α = ∑V α iε i (29) i where
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where SAND and CLAY are percents of
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Below the transition value, the soi
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To verify the observations concerni
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6. TEMPERATURE EFFECT ON SOIL DIELE
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chamber and the freezer, only one w
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The user interface on the main comp
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soil sample volumetric water conten
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close vicinity of the analyzed obje
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process of measurement is non-destr
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dielectric permittivity change caus
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The values of the refractive index
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The relative, ∆n/∆T, and absolu
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Fig. 25. The temperature effect on
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The temperature effect of TDR soil
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The purpose of the above discussion
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( ,25 + T )( 45 + T ) 49 9 f rel =
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8. THE ACCURACY OF SOIL WATER CONTE
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gravimetric method and the soil ref
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where: a 0 ÷ a 6 are coefficients
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values of p F calculated for the re
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eason of this is the fact that wate
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9 ∆θ = 0,2 ⋅10 ⋅ ∆t = 0.00
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values of θ rel for lower values o
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9. COMPARISON OF OPEN-ENDED COAX AN
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ε" = EC ε d " + (82) 2π fε wher
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dielectric permittivity, the dielec
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The applied lumped capacitance mode
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stainless steel wires soldered to t
Page 94 and 95: ε’ Open Coax and ε b-TDR , exce
Page 96 and 97: − − The difference of the imagi
Page 98 and 99: Integrated Circuit) recently introd
Page 100 and 101: 10.2. Electromechanical microwave s
Page 102 and 103: RF1. Two PIN diodes in series in ea
Page 104 and 105: The significant aspect of the proto
Page 106 and 107: visible for lower values of soil el
Page 108 and 109: In the TDR method the signal propag
Page 110 and 111: description of functional and techn
Page 112 and 113: MASTER modules are wireless transce
Page 114 and 115: time the Real Time Clock module wak
Page 116 and 117: ase station distinguishes A SLAVE d
Page 118 and 119: sensor, format the data received fr
Page 120 and 121: 12. SOIL WATER STATUS MONITORING DE
Page 122 and 123: D-LOG/mpts is a moisture/pressure/t
Page 124 and 125: For compatibility reasons it uses t
Page 126 and 127: D-LOG/mts (Fig. 59) is a TDR (Time-
Page 128 and 129: 12.4. FP/m, FP/mts - Field Probe fo
Page 130 and 131: inside of a separate polyethylene b
Page 132 and 133: differential water capacity and the
Page 134 and 135: − maximum number of LP/p probes t
Page 136 and 137: 12.7. LP/t - Laboratory Probe for s
Page 138 and 139: From the collected data set, after
Page 140 and 141: 25. de Loor G.P.: Dielectric proper
Page 142 and 143: TDR. Symposium on Time Domain Refle
Page 146 and 147: Fig. 14. Fig. 15. Fig. 16. Fig. 17.
Page 148 and 149: Fig. 38. The three-rod TDR probe -
Page 150 and 151: Fig. 67. A set of LP/ms and LP/p LO
Page 152: Table 17. An example of the executa
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