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Neutron method for measuring soil moisture content and its future
ABSTRACTS
103
81. M. van der Westbedzm. On the possibility of measuring soil moisture with highfrequency electro-magnetic waves. S. Atr. J. agric. Sci., 1964, 7 (3) 589-590; bibL 2, illus. Two parallel wires 2 in. apart were stretched over ~ , 38 ft. and one end was connected to a specially constructed oscillator having a frequency of 7 mc/s, the other end being left open. The wires passed through the centre of a box 140× 14"5× 12 crn filled with a calculated volume of sand. The voltage minimum was determined with a sfiding contact connected through a germanium diode to a d.c. voltmeter. Water was added to 10 per cent by volume of the sand and the distance determined between the voltage minimum and an optional reference point. Daily determinations made while the sand was drying out and over several more drying cycles indicated that this method could be useful for determining the m.c. of large volumes of soil. [N.I.A.E.] 82. C . P . Wroth and R. EL Bmsett. A Stress-Strain Relationship for the Shearing Behaviour of a Sand. Geotechnique, Vol. XV, No. 1, March 1965. Mathematical equations based on exponential functions are proposed for describing the shear stress-strain characteristics of a sand. As well as fitting accurately the experimental results obtained from tests on cohesionless granular media in the simple shear apparatus, these equations also have the virtue of taking fully into account the relatively large changes of volume and/or pressure that always accompany the deformation of granular materials. This is achieved by considering the progress of any test in terms of a new parameter which, in effect, is a direct measure of the difference between the state of the sample (at a particular stage of the test) and the ultimate critical state to which it aspires. The equations are applicable to an infinite variety of tests each with a different degree of volume change (or drainage) ranging from the fully drained to the completely undrained condition. Three basic equations are used to obtain a complete specification of the relevant stress and strain parameters observed throughout a tesL [Author's summary.] 83. V . A . Yemalyuov, L. I, l k s k ~ sad V, L Osipov. [Neutron method for measuring soil moisture content and its future]. Soviet Soil Sci., 1963, (7) 708-714; bibl. 4, illus. The neutron scattering moisture meters consist of a probe, a pulse recorder, a power supply and a standard moderator-box. The detectors in the probes of the neutron moisture meters are boron proportional and scintillation counters of thermal neutrons with semiconductor diodes and triodes. Thermal neutrons can also be detected with ordinary gas-discharge gamma-beta counters (especially halogen counters operating at 400 V) using cadmium screens and activation indicators. Super thermal neutrons are detected by slowing them down using a cadmium filter. The effect is studied of the chemical composition, density and particle size composition of the soil, the design of the probe, and the geometry of the measurements. Probe designs investigated include beta-gamma counters with cadmium screen, a boron slow neutron detector and a scintillation detector. The theory is expounded. [N.I.A.E.] These abstracts have been collected by P. E. R. Cook of the Department of Agricultural Engineering, The University of Newcastle upon Tyne. Most of the literature in Agricultural and Automotive engineering from all over the world is reviewed in the Abstracts published by the National Institute of Agricultural Engineering, Silsoe, Bedford and in the Monthly Summaries prepared by the Motor Industry Research Association, Lindley, Warwickshire. A selection from these lists are included in the above abstracts. The following is a list of the publications searched in addition with a view to covering the remaining large field of Civil Engineering. The relevant and important field of Military Engineering is not covered because the abstractor has no access to it. (I) American Soc. Civil Eng.--J. Soil Mech Foundations Divn, New York. (2) Geotechnique--Inst Civil Eng., London. (3) Road Abstracts, Road Research Lab., West Drayton, Middlesex. (4) Engineering---36 Bedford St., London. (5) The Engineer---28 Essex St, London. (6) The Overseas Engineer--Bowling Green Lane, London. (7) The Charted Mech. Engr.--Inst. Mech. Eng., London. (8) Mechanical Engineering---Am. Soc. Mech. Engnr.0 New York. (9) Journal of App. Mech.--Am. Soc. Mech. Engnr., New York. (10) Applied Mechanics Review--Am. Soc. Mech. Engineers, New York. (11) Agricultural Engineering---Am. Soc. Agric. Engnr., Michigan, U.S.A. (12) J. Agric. Eng. Res.--N.I.A.E., Bedford.
104
ABSTRACTS
(13) U$. Govt. Res. Dev. Repts.--Dept. of Commerce, Springfield, Va. (14) Technical Translations---U.S. Dept. of Comm., Sprinsfield, Va. (15) Civil Engineering, Buckingham St., London. (16) Excavating En gineer--Barrington, Illinois. (17) Roads and Road Const.--Victoria St., London. (18) Civil Engineerins--Am. Soc. Civil Engnrs., New York. (19) Automotive Design Engineering--Rowse Muir Publications, London.
103
81. M. van der Westbedzm. On the possibility of measuring soil moisture with highfrequency electro-magnetic waves. S. Atr. J. agric. Sci., 1964, 7 (3) 589-590; bibL 2, illus. Two parallel wires 2 in. apart were stretched over ~ , 38 ft. and one end was connected to a specially constructed oscillator having a frequency of 7 mc/s, the other end being left open. The wires passed through the centre of a box 140× 14"5× 12 crn filled with a calculated volume of sand. The voltage minimum was determined with a sfiding contact connected through a germanium diode to a d.c. voltmeter. Water was added to 10 per cent by volume of the sand and the distance determined between the voltage minimum and an optional reference point. Daily determinations made while the sand was drying out and over several more drying cycles indicated that this method could be useful for determining the m.c. of large volumes of soil. [N.I.A.E.] 82. C . P . Wroth and R. EL Bmsett. A Stress-Strain Relationship for the Shearing Behaviour of a Sand. Geotechnique, Vol. XV, No. 1, March 1965. Mathematical equations based on exponential functions are proposed for describing the shear stress-strain characteristics of a sand. As well as fitting accurately the experimental results obtained from tests on cohesionless granular media in the simple shear apparatus, these equations also have the virtue of taking fully into account the relatively large changes of volume and/or pressure that always accompany the deformation of granular materials. This is achieved by considering the progress of any test in terms of a new parameter which, in effect, is a direct measure of the difference between the state of the sample (at a particular stage of the test) and the ultimate critical state to which it aspires. The equations are applicable to an infinite variety of tests each with a different degree of volume change (or drainage) ranging from the fully drained to the completely undrained condition. Three basic equations are used to obtain a complete specification of the relevant stress and strain parameters observed throughout a tesL [Author's summary.] 83. V . A . Yemalyuov, L. I, l k s k ~ sad V, L Osipov. [Neutron method for measuring soil moisture content and its future]. Soviet Soil Sci., 1963, (7) 708-714; bibl. 4, illus. The neutron scattering moisture meters consist of a probe, a pulse recorder, a power supply and a standard moderator-box. The detectors in the probes of the neutron moisture meters are boron proportional and scintillation counters of thermal neutrons with semiconductor diodes and triodes. Thermal neutrons can also be detected with ordinary gas-discharge gamma-beta counters (especially halogen counters operating at 400 V) using cadmium screens and activation indicators. Super thermal neutrons are detected by slowing them down using a cadmium filter. The effect is studied of the chemical composition, density and particle size composition of the soil, the design of the probe, and the geometry of the measurements. Probe designs investigated include beta-gamma counters with cadmium screen, a boron slow neutron detector and a scintillation detector. The theory is expounded. [N.I.A.E.] These abstracts have been collected by P. E. R. Cook of the Department of Agricultural Engineering, The University of Newcastle upon Tyne. Most of the literature in Agricultural and Automotive engineering from all over the world is reviewed in the Abstracts published by the National Institute of Agricultural Engineering, Silsoe, Bedford and in the Monthly Summaries prepared by the Motor Industry Research Association, Lindley, Warwickshire. A selection from these lists are included in the above abstracts. The following is a list of the publications searched in addition with a view to covering the remaining large field of Civil Engineering. The relevant and important field of Military Engineering is not covered because the abstractor has no access to it. (I) American Soc. Civil Eng.--J. Soil Mech Foundations Divn, New York. (2) Geotechnique--Inst Civil Eng., London. (3) Road Abstracts, Road Research Lab., West Drayton, Middlesex. (4) Engineering---36 Bedford St., London. (5) The Engineer---28 Essex St, London. (6) The Overseas Engineer--Bowling Green Lane, London. (7) The Charted Mech. Engr.--Inst. Mech. Eng., London. (8) Mechanical Engineering---Am. Soc. Mech. Engnr.0 New York. (9) Journal of App. Mech.--Am. Soc. Mech. Engnr., New York. (10) Applied Mechanics Review--Am. Soc. Mech. Engineers, New York. (11) Agricultural Engineering---Am. Soc. Agric. Engnr., Michigan, U.S.A. (12) J. Agric. Eng. Res.--N.I.A.E., Bedford.
104
ABSTRACTS
(13) U$. Govt. Res. Dev. Repts.--Dept. of Commerce, Springfield, Va. (14) Technical Translations---U.S. Dept. of Comm., Sprinsfield, Va. (15) Civil Engineering, Buckingham St., London. (16) Excavating En gineer--Barrington, Illinois. (17) Roads and Road Const.--Victoria St., London. (18) Civil Engineerins--Am. Soc. Civil Engnrs., New York. (19) Automotive Design Engineering--Rowse Muir Publications, London.