نتایج جستجو برای: soil behavior
تعداد نتایج: 795067 فیلتر نتایج به سال:
Land aridity has been projected to increase with global warming. Such projections are mostly based on off-line aridity and drought metrics applied to climate model outputs but also are supported by climate-model projections of decreased surface soil moisture. Here we comprehensively analyze soil moisture projections from the Coupled Model Intercomparison Project phase 5, including surface, tota...
Soil complexity and environmental heterogeneity may be viewed as a consequence of deterministic chaotic dynamics and therefore highly irregular patterns with so-called multifractal behavior should be common. This approach introduces a distinct viewpoint as compared with fractal models for soil surface roughness based on fractional Brownian motion. It suggests that it would be useful to move awa...
The fine-grained surface material at the Apollo 11 landing site is a brownish, medium-gray, slightly cohesive granular soil, with bulky grains in the silt-to-fine-sand range, having a specific gravity of 3.1 and exhibiting adhesive characteristics. Within the upper few centimeters, the lunar soil has an average density of about 1.6 grams per cubic centimeter and is similar in appearance and beh...
We studied effects of parasitism by two Tiphia species (Hymenoptera: Tiphiidae) on burrowing behavior of their respective scarabaeid hosts and tested the hypothesis that parasitoid alteration of host hormones accounts for the observed behavioral change. In turf Þeld-plots, thirdinstar masked chafer grubs, Cyclocephala sp., parasitized by native Tiphia pygidialis Allen burrowed to depths of 12Ð1...
An extensive ice body is buried under less than 20 cm to several meters of debris in Beacon Valley (Dry Valleys, Antarctica). The thermal behavior of the upper 20 m of permafrost, including the annually freezing and thawing surface (active layer) in this region of low relative humidity and very low annual precipitation, has great scientific interest. Distinctly different behavior from wet, arct...
Dynamic properties of the soils at the Lotung test site, Lotung, Taiwan, are estimated from seismic vertical array measurements (input± output data sets) using both time-invariant and time-variant parametric modeling methods (system identi®cation). Soil properties are directly mapped from model parameters to an equivalent lumped mass model of the soil interval. Shear stiffness and damping ratio...
This paper investigates kinetic behavior of a planetary rover with attention to tire-soil traction mechanics and articulated body dynamics, and thereby study the control when the rover travels over natural rough terrain. Experiments are carried out with a rover test bed to observe the physical phenomena of soils and to model the traction mechanics, using the tire slip ratio as a state variable....
Hydraulic coefficients of a porous media such as hydraulic conductivity K(θ) and diffusivity D(θ) have a controlling role in the evaluation of groundwater flow and pollutant transport behavior. Therefore, successful porous media flow evaluation depends on the accurate determination of its hydraulic coefficients. But it is hard and time consuming to measure. Values for these coefficients accurat...
In the context of sustainable development which is a balancing act between the fulfilment of human needs and the protection of the natural environment, the use of natural fibers such as coir in geotechnical applications is desirable. Reinforcing the soil with coir fibers/coir geotextiles is a cost effective solution to the ground/soil improvement problems. The effects of fiber parameters on the...
The behavior of simetryn and thiobencarb in flooded rice soil was investigated in a 2-year study. The concentrations of simetryn and thiobencarb were in the hundreds of μg kg−1 in the top soil layer (0–5 cm) and became significantly lower in tens of μg kg−1 in the deeper soil layers (5–10 and 10–15 cm). The half-lives of the two herbicides were also shorter (36 and 17 days for simetryn and thio...
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