Field nutrient distribution maps obtained from the study on soil variations within fields are the basis of precision agriculture. The quality of these maps for management depends on the accuracy of the predicted value...Field nutrient distribution maps obtained from the study on soil variations within fields are the basis of precision agriculture. The quality of these maps for management depends on the accuracy of the predicted values, which depends on the initial sampling. To produce reliable predictions efficiently the minimal sampling size and combination should be decided firstly, which could avoid the misspent funds for field sampling work. A 7.9 hectare silage field close to the Agricultural Research institute at Hillsborough, Northern Ireland, was selected for the study. Soil samples were collected from the field at 25 m intervals in a rectangular grid to provide a database of selected soil properties. Different data combinations were subsequently abstracted from this database for comparison purposes, and ordinary kriging used to produce interpolated soil maps. These predicted data groups were compared using least significant difference (LSD) test method. The results showed that the 62 sampling sizes of triangle arrangement for soil available K were sufficient to reach the required accuracy. The triangular sample combination proved to be superior to a rectangular one of similar sample size.展开更多
In situ and laboratory studies of sea -surface microlayer microlayer sampling methods using glass plate , rotating drum , screen and funnel samplers were conducted . For glass plate and rotating drum samplers, surface...In situ and laboratory studies of sea -surface microlayer microlayer sampling methods using glass plate , rotating drum , screen and funnel samplers were conducted . For glass plate and rotating drum samplers, surface microlayer samples of different thickness were collected by controlling their withdrawal rate and rotating rate. The relationships between pH, surface tension, the concentration of dissolved trace metals Cu and Pb, phophate , particulate mattersand sampling thickness were carefully investigated . It was shown that physicochemical and biological properties obviously at the sampling thickness of about 50 um, which is consistent with the mean thickness of the boundary film in the models of gas exchangee across the sea surface . It is proposed that the apparent sampling thickness of the surface microlayer should be less than 40 μm The factors affecting affecting the sampling thickness are discussed , and the feasibility and applicable conditions for different sampling methods are evaluated .展开更多
Fabrication technology of the Yb3+:Er3+ co-doped glass samples is introduced. Photolummescence (PL) characteristics of a single sample were experimentally investigated. The PL peak intensities of two samples in series...Fabrication technology of the Yb3+:Er3+ co-doped glass samples is introduced. Photolummescence (PL) characteristics of a single sample were experimentally investigated. The PL peak intensities of two samples in series were measured and discussed. The results show that the PL peak intensities of two samples in series depend on pump manners and arrangement of the samples. The better amplification ability can be obtained by two samples in series doped with low-concentration ytterbium instead of a single sample doped with high-concentration ytterbium.展开更多
Erbium-doped glass showing the wider 1.5-um emission band is reported in a novel oxide system TeO2-WO3-Nb2O5 and their thermal stability and optical properties such as absorption, emission spectra, cross-sections and ...Erbium-doped glass showing the wider 1.5-um emission band is reported in a novel oxide system TeO2-WO3-Nb2O5 and their thermal stability and optical properties such as absorption, emission spectra, cross-sections and fluorescence lifetime were investigated. Compared with other glass hosts, the gain bandwidth properties of Er3+ in TWN glass is close to that of bismuth glasses, and larger than those of tellurite, germanate, silicate and phosphate glasses. The broad and flat 4I13/2-4I15/2 emission and the large stimulated emission cross-section of Er3+ ions around 1.5um can be used as host material for potential broadband optical amplifier in the wavelength-division-multiplexing (WDM) network system.展开更多
基金Project supported by the British Council !(No. SHA/ 992/ 297) the Natural Science Foundation of Zhejiang Province, China! (N
文摘Field nutrient distribution maps obtained from the study on soil variations within fields are the basis of precision agriculture. The quality of these maps for management depends on the accuracy of the predicted values, which depends on the initial sampling. To produce reliable predictions efficiently the minimal sampling size and combination should be decided firstly, which could avoid the misspent funds for field sampling work. A 7.9 hectare silage field close to the Agricultural Research institute at Hillsborough, Northern Ireland, was selected for the study. Soil samples were collected from the field at 25 m intervals in a rectangular grid to provide a database of selected soil properties. Different data combinations were subsequently abstracted from this database for comparison purposes, and ordinary kriging used to produce interpolated soil maps. These predicted data groups were compared using least significant difference (LSD) test method. The results showed that the 62 sampling sizes of triangle arrangement for soil available K were sufficient to reach the required accuracy. The triangular sample combination proved to be superior to a rectangular one of similar sample size.
文摘In situ and laboratory studies of sea -surface microlayer microlayer sampling methods using glass plate , rotating drum , screen and funnel samplers were conducted . For glass plate and rotating drum samplers, surface microlayer samples of different thickness were collected by controlling their withdrawal rate and rotating rate. The relationships between pH, surface tension, the concentration of dissolved trace metals Cu and Pb, phophate , particulate mattersand sampling thickness were carefully investigated . It was shown that physicochemical and biological properties obviously at the sampling thickness of about 50 um, which is consistent with the mean thickness of the boundary film in the models of gas exchangee across the sea surface . It is proposed that the apparent sampling thickness of the surface microlayer should be less than 40 μm The factors affecting affecting the sampling thickness are discussed , and the feasibility and applicable conditions for different sampling methods are evaluated .
基金This work was supported by the National Natural Science Foundation of China(No.6988701),Science and Technology Commission of Liaoning Province (No.20022110) Educational Commission of Liaoning Province(No.202123198)
文摘Fabrication technology of the Yb3+:Er3+ co-doped glass samples is introduced. Photolummescence (PL) characteristics of a single sample were experimentally investigated. The PL peak intensities of two samples in series were measured and discussed. The results show that the PL peak intensities of two samples in series depend on pump manners and arrangement of the samples. The better amplification ability can be obtained by two samples in series doped with low-concentration ytterbium instead of a single sample doped with high-concentration ytterbium.
基金This work was supported by the Project oftheNational NNatural Science Foundation of China(No.60207006) and Optical Science and Technology of Shanghai(No022261046).
文摘Erbium-doped glass showing the wider 1.5-um emission band is reported in a novel oxide system TeO2-WO3-Nb2O5 and their thermal stability and optical properties such as absorption, emission spectra, cross-sections and fluorescence lifetime were investigated. Compared with other glass hosts, the gain bandwidth properties of Er3+ in TWN glass is close to that of bismuth glasses, and larger than those of tellurite, germanate, silicate and phosphate glasses. The broad and flat 4I13/2-4I15/2 emission and the large stimulated emission cross-section of Er3+ ions around 1.5um can be used as host material for potential broadband optical amplifier in the wavelength-division-multiplexing (WDM) network system.
