So far path coverage problem has been studied widely to characterize the properties of the coverage of a path or a track in an area induced by a sensor network, in which the path or track is usually treated as a curve...So far path coverage problem has been studied widely to characterize the properties of the coverage of a path or a track in an area induced by a sensor network, in which the path or track is usually treated as a curve and the width of it can be ignored. However, sensor networks often are employed to carry out road surveillance or target tracking, in which the interesting area is only the surface of the road, thus the width of the road must be considered. This paper analyzes the optimal sensing coverage of the road in this kind of applications, assuming that sensor nodes are deployed along both sides of the road determinately. The optimal position of sensor nodes is studied considering the sensing range of sensors and the width of the road, and the purpose is to cover the road surface completely with minimal nodes. The isosceles triangle model is proposed and proved to be the most suitable, that is to say all sensors get the maximal available sensing area if any three nearest sensors located on both sides of the road form an isosceles triangle. Comparing with the equilateral triangle model proposed in other articles, this model increases the coverage rate and supplies complete coverage of the road.展开更多
The Soil and Water Assessment Tool(SWAT) has been widely used throughout the world to model crop growth and nutrient uptake in various types of soils.A greenhouse experiment was performed to validate the process equat...The Soil and Water Assessment Tool(SWAT) has been widely used throughout the world to model crop growth and nutrient uptake in various types of soils.A greenhouse experiment was performed to validate the process equations embedded in SWAT for describing the growth and nutrient uptake of tomatoes in south Florida.The scaled growth curve of greenhouse-grown tomatoes was in close agreement with the theoretical model for field conditions,with the scaling factors being the maximum canopy height and the potential heat units.Similarly,the scaled leaf area index(LAI) growth curve and the scaled root depth curve for greenhousegrown tomatoes agreed with the SWAT functions,with the scaling factors being the maximum LAI and maximum root depth.The greenhouse experiment confirmed that the growth of biomass is a linear function of the intercepted photosynthetically active radiation.The fractions of nutrients in the plant biomass under greenhouse conditions were found to be on the order of 60% of those fractions observed in the field.Values of the initial P distribution(0.2 mg kg -1),initial ratio of mineral stable P to mineral active P(50:1),and initial ratio of humic N to humic P(2.4:1) were determined from soil measurements and can be used for field simulations.The conventional saturation-excess model for soil-water percolation was used to predict the movement of water in the top 10 cm of the greenhouse containers and the results agreed well with measurements.展开更多
文摘So far path coverage problem has been studied widely to characterize the properties of the coverage of a path or a track in an area induced by a sensor network, in which the path or track is usually treated as a curve and the width of it can be ignored. However, sensor networks often are employed to carry out road surveillance or target tracking, in which the interesting area is only the surface of the road, thus the width of the road must be considered. This paper analyzes the optimal sensing coverage of the road in this kind of applications, assuming that sensor nodes are deployed along both sides of the road determinately. The optimal position of sensor nodes is studied considering the sensing range of sensors and the width of the road, and the purpose is to cover the road surface completely with minimal nodes. The isosceles triangle model is proposed and proved to be the most suitable, that is to say all sensors get the maximal available sensing area if any three nearest sensors located on both sides of the road form an isosceles triangle. Comparing with the equilateral triangle model proposed in other articles, this model increases the coverage rate and supplies complete coverage of the road.
文摘The Soil and Water Assessment Tool(SWAT) has been widely used throughout the world to model crop growth and nutrient uptake in various types of soils.A greenhouse experiment was performed to validate the process equations embedded in SWAT for describing the growth and nutrient uptake of tomatoes in south Florida.The scaled growth curve of greenhouse-grown tomatoes was in close agreement with the theoretical model for field conditions,with the scaling factors being the maximum canopy height and the potential heat units.Similarly,the scaled leaf area index(LAI) growth curve and the scaled root depth curve for greenhousegrown tomatoes agreed with the SWAT functions,with the scaling factors being the maximum LAI and maximum root depth.The greenhouse experiment confirmed that the growth of biomass is a linear function of the intercepted photosynthetically active radiation.The fractions of nutrients in the plant biomass under greenhouse conditions were found to be on the order of 60% of those fractions observed in the field.Values of the initial P distribution(0.2 mg kg -1),initial ratio of mineral stable P to mineral active P(50:1),and initial ratio of humic N to humic P(2.4:1) were determined from soil measurements and can be used for field simulations.The conventional saturation-excess model for soil-water percolation was used to predict the movement of water in the top 10 cm of the greenhouse containers and the results agreed well with measurements.
