The spatial production allocation model (SPAM) is one of the broadest spatial models of crop distribution and applies a cross-entropy method to downscale the global area and yield for multiple crops in the years 2000 and 2005 with a resolution of 5 arc min. To evaluate the allocation accuracy of SPAM for three staple crops (rice, wheat, and maize) in China, we compared these crop maps with remote-sensed cropland data derived from national land cover datasets. This comparison was conducted using a scheme that accounts for spatial differences at the pixel level. Overall, the map of maize has the highest area accuracy, with 64% reasonable pixels (covering 96% of the total maize area); these values were 57% (90% coverage) and 44% (81% coverage) for the wheat and rice maps, respectively. On the provincial scale, the area accuracies of crop maps in the top 10 provinces are better than those of the other provinces. Furthermore, the crop area consistency in rain-fed cropland is better than that in irrigated cropland. These evaluations provide decision makers with information regarding the strengths and weaknesses of SPAM products. This study also recommends priorities for further work to improve the reliability, utility, and periodic repeatability of crop distribution products.
To meeting the testing requirements of high-precision optical surfaces, the absolute testing technology was used for the
optical testing process. Three-Position absolute measurements with the advantage of few requested testing and testing
conditions are often easily satisfaction were used to high-precision spherical surface shape testing. However in the error
process of three-position absolute measurements, cat's position error has an important impact on finally measurement
results, so three-position absolute measurement simulation and error analysis is necessary. In this paper, optical design
software ZEMAX were used to built the model of three-position absolute measurement and three-position absolute
sphere testing algorithm was used to get actual surface. Finally, some experiments about how to determine the location
of standard cat's eye position were carried on and the experiment's result shows that defocus is the most important factor
in cat's eye position measurement.
Sustainability of world crop production and food security has become uncertain. The authors have developed an
environmental research system called Remote Sensing Environmental Monitor (RSEM) for treating carbon sequestration
by vegetation, grain production, desertification of Eurasian grassland, and CDM afforestation/ reforestation to a
background of climate change and economic growth in rising Asian nations. The RSEM system involves vegetation
photosynthesis and crop yield models for grains, including land-use classification, stomatal evaluation by surface energy
fluxes, and daily monitoring for early warning. This paper presents a validation method for RSEM based on carbon
partitioning in plants, focusing in particular on the effects of area sizes used in crop production statistics on carbon
fixation and on sterility-based corrections to accumulated carbon sequestration values simulated using the RSEM
photosynthesis model. The carbonhydrate in grains has the same chemical formula as cellulose in grain plants. The
method proposed by partitioning the fixed carbon in harvested grains was used to investigate estimates of the amounts of
carbon fixed, using the satellite-based RSEM model.
Interferometric measurement, as dominating testing methods, is widely used in the field of optical measurement.
Conventional interferometer subjects to many factors which make the measurement accuracy between λ/10 and λ/20, so
it's difficult to meet the surface testing requirements of high accuracy. Thus the three-position absolute measurement
technique is used to remove the errors which are introduced by reference surface and interferometer itself. The detailed
process and experiment of three-position absolute measurement are given. A misalignment model by rigid body theory is
presented, and the corresponding influence on interferometric measurement result is analyzed. The simulation results by
the presented model are compared with that of Zemax software. By comparing both simulation results, it confirms the
feasibility of the misalignment model.
The authors have developed a photosynthesis crop model for grain production under the background of climate
change and Asian economic growth in developing countries. This paper presents an application of the model to grain
fields of paddy rice, winter wheat, and maize in China and Southeast Asia. The carbon hydrate in grains has the same
chemical formula as that of cellulose in grain vegetation. The partitioning of carbon in grain plants can validate
fixation amounts of computed carbon using a satellite-based photosynthesis model. The model estimates the
photosynthesis fixation of rice reasonably in Japan and China. Results were validated through examination of carbon
in grains, but the model tends to underestimate results for winter wheat and maize. This study also provides daily
distributions of the PSN, which is the CO2 fixation in Asian areas combined with a land-cover distribution classified
from MODIS data, NDVI from SPOT VEGETATION, and meteorological re-analysis data by European Centre for
Medium-Range Forecasts (ECMWF). The mean CO2 and carbon fixation rates in paddy areas were 25.92 (t CO2/ha)
and 5.28 (t/ha) in Japan, respectively. The method is based on routine observation data, enabling automated
monitoring of crop yields.
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