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From the collected data set, after further processing, one can obtain a complete set of the unsaturated water flow characteristics of the soil, that is: water retention (PF-curve), unsaturated water conductivity (k-function), differential water capacity and unsaturated water diffusivity. Features of LP/p: • Sensor: − pressure diaphragm: a 15 mm long ceramic − − cup, 3 mm in diameter pressure transducer: an integrated, fully active Wheatstone bridge with four piezoresistive strain gauge resistors diffused into a silicon diaphragm − air entry pressure: about 900 mbar • Offset drift: ± 20 mbar/month • Relative error: ± 15 % • Resolution: 1 mbar • Delay: 0 to 800 mbar in about 120 s, 800 to 0 mbar in about 3 s • Cable length: 2 m • Installation hole: 8 mm diameter tapped with 8x1 mm thread. Fig. 70. Reading instantaneous profiles of soil water capillary pressure, water content and salinity from arrays of the LP/p and LP/ms miniprobes 137
13. REFERENCES 1. Agilent Application Note 922: Applications of PIN Diodes. 1999. 2. Agilent Application Note 1304-2: Time Domain Reflectometry Theory. 2002. 3. Alharthi A., Lange J.: Soil water saturation: dielectric determination. Water Resour. Res. 23(4), 591-595. 1987. 4. Analog Devices: AD7705/AD7706 2/3 Channel 16-Bit Sigma-Delta ADC. 1998. 5. Annan A.P.: Report of activities, Part B, Geol. Surv. Can. Paper 77-1B. 1979. 6. Arble W.C., Shaw M.D.: Bibliography on the methods for determining soil moisture. Eng. Res. Bull. B-78, Coll. Of Eng. End. Arch., Univ. Park, Penn., 1959. 7. Baker J.M., Allmaras R.W.: System for automating and multiplexing soil moisture measurementby time-domain reflectometry. Soil Sci. Soc. Am. J. 54: 1-6. 1990. 8. Baranowski J., Rusek A., Ramotowski M., Misiaszek S., Nowakowski W.: Wide bandwidth stroboscope synchroscopes (in Polish). WNT, Warsaw, 1972. 9. Birchak J.R., Gardner C.G., Hipp J.E., Victor J.M.: High dielectric constant microwave probes for sensing soil moisture. Proc. of the IEEE. 62:(1):93-98. 1974. 10. Blackham D.V., Pollard R.D.: 1997. An Improved Technique for Permittivity Measurements Using a Coaxial Probe. IEEE Trans. Instr. Meas., 46(5), 1093-1099. 11. Bohl, H., Roth K.: Evaluation of dielectric mixing models to describe the θ(ε) relation. Symposium in Evanston. Sept. 8-9, 1994. 12. Boyarskii D.A., Tikhonov V.V., Komarova N.Yu.: Model of dielectric constant of bound water in soil for applications of microwave remote sensing. Progress In Electromagnetic Research, 35:251-269, 2002. 13. Campbell G.S., Gee G.W.: Water potential miscellaneous methods. Agronomy 9, Part 1, 2-nd Ed, 619-633, 1986. 14. Chełkowski A. Physics of dielectrics (in Polish). PIW, Warsaw. 1972. 15. Chipcon Smart RF CC1000 - Single Chip Very Low Power RF Transceiver (http://www.chipcon.com/files/CC1000_Data_Sheet_2_2.pdf), 2004. 16. COTO Technology: Technical and Application Information (Relays), Coto Technology Website: www.cotorelay.com 17. CRC handbook of chemistry and physics (ed. R.C. Wheast). CRC Press Inc. Boca Raton. Florida. USA. 1979. 18. DS18B20: Programmable Resolution 1-Wire Digital Thermometer Data Sheet, Dallas Semiconductors – Maxim. 19. Dalton F.N., Herkelrath W.N., Rawligs D.S., Rhoades J.D.: Time-domain reflectometry simultaneous measurement of soil water content and electrical conductivity with a single probe. Science. 224:989-990. 1984. 20. Dalton, F. N., van Genuchten M. Th.: The time-domain reflectometry method for measuring soil water content and salinity. Geoderma. 38:237-250. 1986. 21. Dasberg S., Dalton F.N.: Time Domain Reflectometry field measurements of soil water content and electrical conductivity. Soil Sci. Soc. Am. J., Vol. 49, 293-297, 1985. 22. Davis, J.L., Annan A.P.: Electromagnetic detection of soil moisture: progress report I. Canadian Journal of Remote Sensing. 3:76-86. 1977. 23. Davis J. L., W. J. Chudobiak: In situ meter for measuring relative permittivity of soils, Geol. Surv. Can., Paper 75-1, Part A, 1985. 24. Debye P.: Polar Molecules. Dover. Mineola. N.Y., 1929. 138
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TDR METHOD FOR THE MEASUREMENT OF W
Page 4 and 5:
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
Page 88 and 89: dielectric permittivity, the dielec
Page 90 and 91: The applied lumped capacitance mode
Page 92 and 93: 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 140 and 141: 25. de Loor G.P.: Dielectric proper
Page 142 and 143: TDR. Symposium on Time Domain Refle
Page 144 and 145: 100. Whalley W.R.: Considerations o
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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