3,713 research outputs found
Labview-based FPGA implementation of sensor data acquisition for human body motion measurement
Measuring body motion is crucial to identify any abnormal neuromuscular control, biomechanical disorders and injury prevention in various applications such as rehabilitation [1], [2], sport science [3],[4], surveillance [5], and virtual reality [6]. The measurement can be performed by using vision-based [7]-[9] and non-vision-based [10]-[12] systems. The vision-based systems use optical sensors, such as cameras, to track human movements. Whilst the non-vision-based systems employ sensor technology, such as magnetic, and inertial, attached to the human body to collect human movement information. The vision-based systems offer a more accurate system, however, in this work, the non-vision-based systems are employed as it offers portability as one of the advantages
Residual effects of fallows on selected soil hydraulic properties in a kaolinitic soil subjected to conventional tillage (CT) and no tillage (NT)
Improved fallows have been used to reduce time required for soil fertility regeneration after cropping in low input agricultural systems. In semi-arid areas of Southern Africa, Acacia angustissima and Sesbania sesban are among some of the more widely used improved fallow species. However the residual effects of improved fallows on soil hydraulic properties during the cropping phase is not known. The aim of this study was to quantify the residual effects of fallows and tillage imposed at fallow termination on soil hydraulic properties (infiltration rates, hydraulic conductivity and soil porosity) during the cropping phase. Treatments evaluated were planted fallows of Acacia angustissima, Sesbania sesban and natural fallow (NF) and continuous maize as a control. Steady state infiltration rates were measured using a double ring infiltrometer and porosity was calculated as the difference between saturated infiltration rates and tension infiltration measurements on an initially saturated soil. Unsaturated hydraulic conductivity (K-o) and mean pore sizes of water conducting pores were measured using tension infiltrometer at tensions of 5 and 10 cm of water on an initially dry soil. While there was no significant difference in steady state infiltration rates from double ring infiltrometer measurements among the fallow treatments, these were significantly higher than the control. The steady state infiltration rates were 36, 67, 59 and 68 mm h(-1) for continuous maize, A. angustissima, S. sesban and NF respectively. Tillage had no significant effect on steady state infiltration rate. Pore density at 5 cm tension was significantly higher in the three fallows than in maize and varied from 285-443 m(-2) in fallows, while in continuous maize the pore density was less than 256 m(-2). At 10 cm tension pore density remained significantly higher in fallows and ranged from 4,521-8,911 m(-2) compared to 2,689-3,938 m(-2) in continuous maize. Unsaturated hydraulic conductivities at 5 cm tension were significantly higher in fallows than in continuous maize and were 0.9, 0.7, 0.8 cm and 0.5 cm h(-1) for A. angustissima, S. sesban, NF and continuous maize, respectively. However there were no significant treatment differences at 10 cm tension. Fallows improved infiltration rates, hydraulic conductivity and soil porosity relative to continuous maize cropping. Through fallowing farmers can improve the soils hydraulic properties and porosity, this is important as it affects soil water recharge, and availability for plant growt
Saturated hydraulic conductivity determined by on ground mono-offset Ground-Penetrating Radar inside a single ring infiltrometer
In this study we show how to use GPR data acquired along the infiltration of
water inside a single ring infiltrometer to inverse the saturated hydraulic
conductivity. We used Hydrus-1D to simulate the water infiltration. We
generated water content profiles at each time step of infiltration, based on a
particular value of the saturated hydraulic conductivity, knowing the other van
Genuchten parameters. Water content profiles were converted to dielectric
permittivity profiles using the Complex Refractive Index Method relation. We
then used the GprMax suite of programs to generate radargrams and to follow the
wetting front using arrival time of electromagnetic waves recorded by a
Ground-Penetrating Radar (GPR). Theoretically, the 1D time convolution between
reflectivity and GPR signal at any infiltration time step is related to the
peak of the reflected amplitude recorded in the corresponding trace in the
radargram. We used this relation ship to invert the saturated hydraulic
conductivity for constant and falling head infiltrations. We present our method
on synthetic examples and on two experiments carried out on sand soil. We
further discuss on the uncertainties on the retrieved saturated hydraulic
conductivity computed by our algorithm from the van Genuchten parameters
Optional Soil Infiltration Protocol
The purpose of this resource is to determine the rate at which water soaks into the ground. Students place two cans into the soil and add water to them to a depth of at least 5 cm. Students measure and record the time it takes the water level to drop a fixed 2 - 4 cm distance. Students repeat the measurement to determine how easily water moves vertically through the soil. Educational levels: Primary elementary, Intermediate elementary, Middle school, High school
Artificial recharge – measurement of soil infiltration in Rožnov pod Radhoštěm
The purpose of this study is to evaluate the potential for infiltration in a study area – Rožnov pod Radhoštěm, the Czech Republic. The results are important for the future design of an artificial recharge structure as a method to store water underground in times of water surplus. A total of six measurements of infiltration were made using a double ring infiltrometer on selected prospective sites for the future application of artificial recharge. The results of infiltration tests were analysed based on the Philip`s model. The steady soil infiltration rates ranged from 28 cm∙h-1 to 70.38 cm∙h-1and the cumulative soil infiltration ranged from 58 cm to 68 cm
Surface Water Infiltration in Loess Soils of the Lower Mississippi River Valley: An Emphasis on Land Use
The Alluvial Aquifer is the shallowest and most heavily used groundwater aquifer in the Lower Mississippi River Valley, particularly in the Delta region of eastern Arkansas. However, the Alluvial Aquifer is being depleted faster than the rate of recharge, primarily due to excessive withdrawals for irrigated crop production. Since extensive irrigation in the highly agriculturally productive Delta region of eastern Arkansas has been a main culprit in the groundwater depletion issues the region faces, a better understanding of how ecological factors and/or agricultural best management practices could possibly increase infiltration, to consequently increase recharge, are needed in order to either slow down or reverse the declining aquifer levels through the Delta region of eastern Arkansas. Therefore, the objective of this study was to evaluate the effects of landuse on surface water infiltration into alluvial and loessial soils in the Delta region of eastern Arkansas. Landuse combinations of interest included conventional and no-tillage agricultural practices, deciduous and coniferous forests, and native/natural grasslands. Replicate infiltration measurements were conducted using a double-ring infiltrometer, with a 15-cm inner-ring diameter, across multiple sites representing each of the five landuses. Despite the initial soil water content being greater (P \u3c 0.05) in the grassland than in all other ecosystems, the overall infiltration rate into the deciduous forest ecosystem (1.2 cm hr-1) was greater (P \u3c 0.05) than all other landuse types, which did not differ and averaged 0.10 cm hr-1. In addition, though the slope of the relationship between the natural logarithm of the infiltration rate versus the mid-point of time was unaffected (P \u3e 0.05) by landuse, the intercept parameter differed (P \u3c 0.05) among landuses. Results of this study demonstrated that landuse significantly affects infiltration processes in the fine-textured loessial and alluvial soils in the Delta region of eastern Arkansas; thus, further research is warranted into factors that can increase surface infiltration and potentially groundwater recharge
Determination of hydrophobicity index: standard and mini disk infiltrometers
Non-Peer ReviewedSoil hydrophobicity drastically impacts water infiltration, retention and transport.
Hydrophobicity index, a ratio of the sorptivity of water to ethanol, is a common measure
of soil hydrophobicity. The sorptivity may be measured using the disk infiltrometer. The
standard disk infiltrometer is large, cumbersome and expensive while the mini disk
infiltrometer is compact and readily accessible. The objective of this study was to
determine if the mini disk infiltrometer is comparable to the standard disk infiltrometer as
a means of analyzing the soil hydrophobicity index. The soil hydrophobicity index was
calculated from the sorptivities of water and ethanol as determined by both infiltrometer
methods. Results indicate no statistical difference between soil hydrophobicity indices
calculated from the standard and mini disk infiltrometer methods
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