An equation to predict the leaching of surface-applied nitrate

1975 ◽  
Vol 85 (3) ◽  
pp. 443-454 ◽  
Author(s):  
I. G. Burns
Keyword(s):  
Soil Profile ◽  
Field Capacity ◽  
Weather Conditions ◽  
Published Data ◽  
Wide Range ◽  
The Mean ◽  
New Equation ◽  
Image Position ◽  
Good Agreement

SUMMARYThe fraction (f) of surface-applied nitrate leached below any depth h cm in a uniform soil profile may be calculated from the equationwhere P is the quantity of water draining through the soil (in cm) and Vm is the percentage volumetric field capacity. The fraction of nitrate retained is then (1—f).This equation has been tested using published data. Values of h corresponding to the mean displacement (f = 0·5) were calculated for a wide range of soil and weather conditions and the results compared with mean displacements measured in the field. Similar comparisons were made with the leaching equation of Rousselle (1913) and Levin (1964). The new equation gives good agreement with the observed data, whereas the Rousselle-Levin equation generally overestimates the mean displacement of nitrate. Methods of applying the equations to field situations are discussed.

Equations to predict the leaching of nitrate uniformly incorporated to a known depth or uniformly distributed throughout a soil profile

1976 ◽  
Vol 86 (2) ◽  
pp. 305-313 ◽  
Author(s):  
I. G. Burns
Keyword(s):  
Soil Profile ◽  
Field Capacity ◽  
Approximate Form ◽  
Field Soils ◽  
The Mean ◽  
Image Position

SummaryEquations to predict the leaching of nitrate either uniformly incorporated to a known depth or uniformly distributed in field soils can be reduced to the approximate form:where f is the fraction of nitrate leached below h cm in a soil of field capacity Vm (% by volume) after P cm of drainage has passed through the profile. If nitrate is initially incorporated uniformly to a depth of w cm, then x = h – ½w(where h ≥ w); if nitrate is distributed uniformly throughout the whole profile, then x = ½h. For surface-applied nitrate x = h (Burns, 1975).Observed mean displacements in published experiments have been compared with predictions from the equations and from equations in which the mean movement of nitrate and water are assumed equal. The new equations give better agreement with the observed data.

Analytical Prediction of Tubular Light-Pipe Performance Under Arbitrary Sky Conditions

2019 ◽  
Vol 141 (5) ◽  
Author(s):  
Jaromír Petržala ◽  
Ladislav Kómar
Keyword(s):  
Analytical Solution ◽  
Light Guide ◽  
Analytical Prediction ◽  
Optical Efficiency ◽  
Deep Interior ◽  
Wide Range ◽  
The Mean ◽  
Light Guides ◽  
Sky Conditions ◽  
Good Agreement

The tubular light guides are devices allowing deliverance of solar light into deep interior rooms, offices, or underground spaces. Due to considerable costs of such systems, the reasonable assessment of their lighting performance is desirable. To predict accurately their efficiency, precise numerical computations have to be performed. Such computations may be strongly time consuming, mainly when mass calculations are required as it is in case of the so-called climate-based daylight modeling. This paper presents an analytical solution to the optical efficiency of cylindrical straight pipes that is applicable over a wide range of pipe’s parameters and under arbitrary sky luminance conditions. The proposed method gives results in good agreement with ray-tracing numerical simulations—the mean absolute percentage errors are less than 3%—but unlike them, the calculations are much faster. Therefore, it appears to be convenient for daylight modeling, which takes into account utilization of tubular light guide systems in buildings.

scholarly journals Using Decagon EC-5sensors for monitoring soil moisture

2021 ◽  
Vol 4 (3) ◽  
pp. 1-9
Author(s):  
N. A. Shaporina ◽  
E. A. Sayb
Keyword(s):  
Soil Moisture ◽  
Soil Profile ◽  
Technical Specification ◽  
Moisture Flux ◽  
Weather Conditions ◽  
Forest Steppe ◽  
Research Station ◽  
Deep Soil ◽  
High Data ◽  
Wide Range

The aim of the study. To assess the possibilities of using the Decagon EC-5 sensor in research practice, especially under the conditions of its stationary installation; and to study with its help the dynamics of soil profile moistening and moisture migration under different weather conditions. Location and time of the study. The study was carried out on the territory of the Ust-Kamensky (forest-steppe) research station of the Institute of Soil Science and Agrochemistry of the Siberian Branch of the Russian Academy of Sciences (55.005507 N, 83.858635 E). The object of the study was the dark gray forest soil (Luvic Greyzemic Phaeozem). Five Decagon EC-5 sensors were installed at 9, 13, 18, 22 and 27cm depths in a small (30cm deep) soil pit and connected to the Em50 recorder. The necessary calibration was carried out beforehand. The sensors functioned from June 13 to July 7, 2017. Main results. The study showed that this device is suitable for a wide range of applications. According to the sensor readings, it was possible to trace the migration of moisture within the soil profile, as well as to differentiate it into gravitational and capillary water, as well as to establish the fact of precipitation with an accuracy of an hour and to calculate the precipitated amount. Statistical analysis of the obtained data showed low values of data variance and the coefficient of variation, which indicated high data homogeneity. The use of these sensors can improve the traditional flood method for determining the maximum soil water holding capacity. Moreover, detailed recording of soil moisture, provided by Decagon EC-5 sensors, in combination with Thermochron sensors for soil temperature recording, allows to study quantitative indicators of thermal gradient moisture flux at a new level. Conclusions. The study showed that Decagon EC-5 sensors comply with their technical specification and have good prospects for usage both in research and agricultural production. Provided its preliminary calibration and producing the calibration curves for the studied soils, the sensors allow quick and accurate measurement of the soil volumetric moisture content. The frequency and rate of sensor readings takes research on the dynamics and migration of moisture in soils to an entirely new level.

scholarly journals Convective Heat Transfer in a Rotating Cylindrical Cavity

1982 ◽  
Author(s):  
J. M. Owen ◽  
H. S. Onur
Keyword(s):  
Heat Transfer ◽  
Flow Visualization ◽  
Laser Doppler Anemometry ◽  
Reynolds Numbers ◽  
Nusselt Numbers ◽  
Gap Ratio ◽  
Wide Range ◽  
The Mean ◽  
Radial Outflow ◽  
Good Agreement

In order to gain an understanding of the conditions inside air-cooled gas-turbine rotors, flow visualization, laser-doppler anemometry and heat-transfer measurements have been made in a rotating cavity with either an axial throughflow or a radial outflow of coolant. For the axial throughflow tests, a correlation has been obtained for the mean Nusselt number in terms of the cavity gap ratio, the axial Reynolds number and rotational Grashof number. For the radial outflow tests, velocity measurements are in good agreement with solutions of the linear (laminar and turbulent) Ekman layer equations, and flow visualization has revealed the destabilizing effect of buoyancy forces on the flow structure. The mean Nusselt numbers have been correlated, for the radial outflow case, over a wide range of gap ratios, coolant flow rates, rotational Reynolds numbers and Grashof numbers. As well as the three (forced convection) regimes established from previous experiments, a fourth (free convection) regime has been identified.

Convective Heat Transfer in a Rotating Cylindrical Cavity

1983 ◽  
Vol 105 (2) ◽  
pp. 265-271 ◽  
Author(s):  
J. M. Owen ◽  
H. S. Onur
Keyword(s):  
Heat Transfer ◽  
Flow Visualization ◽  
Laser Doppler Anemometry ◽  
Reynolds Numbers ◽  
Nusselt Numbers ◽  
Gap Ratio ◽  
Wide Range ◽  
The Mean ◽  
Radial Outflow ◽  
Good Agreement

In order to gain an understanding of the conditions inside air-cooled, gas-turbine rotors, flow visualization, laser-doppler anemometry, and heat-transfer measurements have been made in a rotating cavity with either an axial throughflow or a radial outflow of coolant. For the axial throughflow tests, a correlation has been obtained for the mean Nusselt number in terms of the cavity gap ratio, the axial Reynolds number, and rotational Grashof number. For the radial outflow tests, velocity measurements are in good agreement with solutions of the linear (laminar and turbulent) Ekman layer equations, and flow visualization has revealed the destabilizing effect of buoyancy forces on the flow structure. The mean Nusselt numbers have been correlated, for the radial outflow case, over a wide range of gap ratios, coolant flow rates, rotational Reynolds numbers, and Grashof numbers. As well as the three (forced convection) regimes established from previous experiments, a fourth (free convection) regime has been identified.

scholarly journals Experimental and Simulation Study of n-Heptane Adsorption on Rutile

2007 ◽  
Vol 25 (7) ◽  
pp. 517-530 ◽  
Author(s):  
G.U. Rakhmatkariev ◽  
A.J. Palace Carvalho ◽  
J.P. Prates Ramalho
Keyword(s):  
Bulk Liquid ◽  
Grand Canonical Monte Carlo ◽  
Differential Heat ◽  
Wide Range ◽  
Adsorption Entropy ◽  
The Mean ◽  
Differential Heat Of Adsorption ◽  
Grand Canonical ◽  
Good Agreement

The adsorption of n-heptane on microcrystalline rutile has been studied experimentally by thermodynamic techniques (adsorption isotherms and microcalorimetry) over a wide range of coverage at 303 K and complemented by Grand Canonical Monte Carlo simulations. The differential heat of adsorption exhibited three descending segments corresponding to the adsorption of n-heptane on three types of surfaces. The mean molar adsorption entropy of n-heptane in the monolayer was less than the entropy of the bulk liquid by ca. −23 J/(mol K), thus revealing a hindered state of motion for the n-heptane molecules on the surface of rutile. Simulations of the adsorption of n-heptane were performed on the three most abundant crystallographic faces of rutile. The adsorption isotherm obtained from the combination of the isotherm for each face weighted by the respective abundance was found to be in good agreement with experimental data. A structural characterization of n-heptane near the surface was also conducted which indicated that the substrate strongly perturbed the distribution of the n-heptane conformations relative to the situation found for the gaseous phase. Adsorbed molecules are predominantly orientated with their long axes, with the zig-zag planes of their backbones parallel to the surface and preferentially aligned along the five-fold cus Ti4+ ions of the faces. Fewer gauche conformations were observed for molecules near the surface than was characteristic of the bulk phase.

scholarly journals Effect of Geometry and Operating Conditions on Spur Gear System Power Loss

1981 ◽  
Vol 103 (1) ◽  
pp. 151-159 ◽  
Author(s):  
N. E. Anderson ◽  
S. H. Loewenthal
Keyword(s):  
Power Loss ◽  
Ball Bearing ◽  
Large Diameter ◽  
Spur Gear ◽  
Operating Conditions ◽  
Published Data ◽  
Wide Range ◽  
Low Torque ◽  
System Power ◽  
Good Agreement

The results of an analysis of the effects of spur gear size, pitch, width and ratio on total mesh power loss for a wide range of speeds, torques and oil viscosities are presented. The analysis uses simple algebraic expressions to determine gear sliding, rolling and windage losses and also incorporates an approximate ball bearing power loss expression. The analysis shows good agreement with published data. Large diameter and fine-pitched gears had higher peak efficiencies but lower part-load efficiency. Gear efficiencies were generally greater than 98 percent except at very low torque levels. Tare (no-load) losses are generally a significant percentage of the full-load loss except at low speeds.

An examination of the sampling observations on wheat of the crop-weather scheme

1936 ◽  
Vol 26 (3) ◽  
pp. 456-487 ◽  
Author(s):  
M. M. Barnard
Keyword(s):  
Soil Temperature ◽  
Growth Rates ◽  
Meteorological Factors ◽  
Weather Conditions ◽  
Wheat Crop ◽  
Quadratic Regression ◽  
Shoot Number ◽  
The Mean ◽  
Good Agreement

The paper gives an account of the results obtained from the data provided by the first three years of the Sampling Observations on Wheat of the Crop-Weather Scheme.Section I describes the Sampling Observations on Wheat of the Crop Weather Scheme which have been initiated in order that the effect of weather conditions may be studied at all stages of the wheat crop’s growth from germination to maturity.In Section II several curves are given which illustrate the progress of the wheat crop. The shoot-number curves bear a marked resemblance to one another subsequent to the period when the shoot number is a maximum in spite of the wide divergences which exist between the maximum shoot numbers themselves.Section III indicates the statistical processes involved in the analyses given in the succeeding sections.Sections IV-VIII are devoted primarily to discussions of the effects of various meteorological factors on specific stages of the crop’s growth. The following results have emerged:The length of the interval from sowing to appearance above ground is shown to be largely dependent on the mean soil temperature during this interval, the relation being well expressed by a quadratic regression. The growth rates of the plants at this time are shown to be in good agreement with those which would be obtained by applying Van ‘t Hoff’s law. Neither the rainfall nor the variation in temperature during the period appear to affect its length.Squarehead’s Master appears above ground consistently later than Yeoman, but the amount of this lag is apparently uninfluenced by variations in soil temperature.

Compression of a Single Transverse Ridge in a Circular Elastohydrodynamic Contact

2003 ◽  
Vol 125 (2) ◽  
pp. 275-282 ◽  
Author(s):  
R. P. Glovnea ◽  
J. W. Choo ◽  
A. V. Olver ◽  
H. A. Spikes
Keyword(s):  
Thin Film ◽  
Film Thickness ◽  
Local Perturbation ◽  
Local Pressure ◽  
Numerical Predictions ◽  
Pure Rolling ◽  
Wide Range ◽  
The Mean ◽  
Theoretical Results ◽  
Good Agreement

A detailed experimental study has been made of the behavior of a 100 nm high transversely oriented ridge in an elastohydrodynamic (EHD) contact. Ultra-thin film interferometry has been used to measure film profiles accurately over a very wide range of lubricant film thicknesses, from a few nanometers up to nearly one micron. This enables the recovery of the amplitude of the inlet perturbation geometry with increasing EHD film thickness to be quantified and compared with numerical predictions. In pure rolling under very thin film conditions, corresponding to a smooth surface EHD film thickness of 10 nm, the surfaces near the ridge were squashed down, leading to a constriction in the film of only about 9 percent of the height of the un-deformed ridge. As the EHD film thickness increased, this deformation recovered until the ridge constriction regained about 90 percent of its original height at film thicknesses of about 1 μm. However this relatively rapid recovery only occurred in pure rolling and is attributed to the local perturbation of film convergence which the ridge generates while in the inlet region. This propagates through the contact at the mean speed of the surfaces and—in pure rolling—acts to diminish the effect of local squeeze. When sliding was present, the ridge remained almost fully deformed even when the mean film thickness was as much as twice the height of the original ridge. In this case, the ridge travels through the contact at a different speed from the mean of the two surfaces. The consequent decoupling of the ridge and the convergence perturbation results in a large local pressure due to squeeze which acts to inhibit recovery of the ridge. The general trend of the behavior of the lubricated ridge is shown to be in good agreement with earlier theoretical results.

Three-fold astigmatism: An important TEM aberration

1993 ◽  
Vol 51 ◽  
pp. 972-973 ◽  
Author(s):  
O.L. Krivanek ◽  
M.L. Leber
Keyword(s):  
High Resolution ◽  
Spatial Frequency ◽  
Field Emission ◽  
Azimuthal Angle ◽  
Hollow Cone ◽  
Small Probe ◽  
Wide Range ◽  
High Resolution Images ◽  
Image Position

Three-fold astigmatism resembles regular astigmatism, but it has 3-fold rather than 2-fold symmetry. Its contribution to the aberration function χ(q) can be written as:where A3 is the coefficient of 3-fold astigmatism, λ is the electron wavelength, q is the spatial frequency, ϕ the azimuthal angle (ϕ = tan-1 (qy/qx)), and ϕ3 the direction of the astigmatism.Three-fold astigmatism is responsible for the “star of Mercedes” aberration figure that one obtains from intermediate lenses once their two-fold astigmatism has been corrected. Its effects have been observed when the beam is tilted in a hollow cone over a wide range of angles, and there is evidence for it in high resolution images of a small probe obtained in a field emission gun TEM/STEM instrument. It was also expected to be a major aberration in sextupole-based Cs correctors, and ways were being developed for dealing with it on Cs-corrected STEMs.

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