The oilseed cake, vetch, rapeseed straw, wheat straw and corn straw were buried in tobacco-planted soil. The decomposition rates, the variation of active organic C and N contents in the residues and the relationship b...The oilseed cake, vetch, rapeseed straw, wheat straw and corn straw were buried in tobacco-planted soil. The decomposition rates, the variation of active organic C and N contents in the residues and the relationship between active organic C and N contents and decomposition rate were investigated. The results showed the decomposition rates of different organic materials were all high in the early period and then low in the late period. Among the organic materials, the decomposition rates ranked as oilseed cake 〉 vetch 〉 wheat straw and rapeseed straw 〉 corn straw. The decomposition rate was positively related to total N content （P〈0.01）, but was negatively related to the active organic C/N ratio （P〈0.01）. However, there was no significant relationship between decomposition ratio and active organic C content. With the proceeding of decomposition, the active organic C content and the total N content in rapeseed straw, vetch, wheat straw and corn straw all trended to increase, but the active organic C/N ratio trended to decrease. However, the variation of active organic C content, total N content and active organic C/N ratio in oilseed cake was on the contrary.展开更多
Using the quantitative error probability density method we studied the S/N ratio of alternately sampled signals digitized by a 4-channel A/D. A complete expression for the S/N ratio of a 4-channel A/D non-uniform samp...Using the quantitative error probability density method we studied the S/N ratio of alternately sampled signals digitized by a 4-channel A/D. A complete expression for the S/N ratio of a 4-channel A/D non-uniform sampling signal was deduced. First we obtained an expression for the S/N ratio of a 1-channel A/D uniform sampling signal when the sampling frequency was equal to or greater than 2 times the frequency of the sampled signal. Based on the S/N ratio of a 2-channel A/D,alternating,non-uniform sampling signal,we analyzed the distribution of quantitative error using the quantitative error probability density method and the distribution convolution formula. From this the S/N ratio expression of a 4-channel A/D sampling signal was deduced. The simulation result shows that the deduced expression is correct.展开更多
To measure the pulsed neutron of a pulsed fission source, an organic scintillation fiber （OSF） detector with separation structure has been designed. The proposed detector employs UV optical fibers as the light guide...To measure the pulsed neutron of a pulsed fission source, an organic scintillation fiber （OSF） detector with separation structure has been designed. The proposed detector employs UV optical fibers as the light guide, and the sensitive region of the detector is composed of a linear array of OSFs, which are individually connected to the optical fibers. The other end of the light guide is coupled to a photomultiplier tube. The key properties of the device including the energy response, time response, neutron sensitivity, and radiation effect of the optical fiber were studied. The detector has a relatively high n/γ sensitivity ratio, which increases as the diameter of the OSF decreases, and ratios greater than 10 could be achieved when the diameter of the OSF is less than 0.3 nun. The sensitivity of the detector to neutrons ranges from 10-14 to 10-20 C cm2/n, and has a response time of 3 ns （FWHM）. The proposed detector is also highly flexible. For instance, the probe can be set close to the source, while the PMT can be placed far away from radiation, allowing easy shielding. Due to these characteristics, pulsed fission neutrons in the vicinity of the source can be accurately measured.展开更多
基金Supported by National Key Technology Research and Development Program(2012BAD40B02Yunnan Provincial Tobacco Company Plan Project(2012YN48)~~
文摘The oilseed cake, vetch, rapeseed straw, wheat straw and corn straw were buried in tobacco-planted soil. The decomposition rates, the variation of active organic C and N contents in the residues and the relationship between active organic C and N contents and decomposition rate were investigated. The results showed the decomposition rates of different organic materials were all high in the early period and then low in the late period. Among the organic materials, the decomposition rates ranked as oilseed cake 〉 vetch 〉 wheat straw and rapeseed straw 〉 corn straw. The decomposition rate was positively related to total N content （P〈0.01）, but was negatively related to the active organic C/N ratio （P〈0.01）. However, there was no significant relationship between decomposition ratio and active organic C content. With the proceeding of decomposition, the active organic C content and the total N content in rapeseed straw, vetch, wheat straw and corn straw all trended to increase, but the active organic C/N ratio trended to decrease. However, the variation of active organic C content, total N content and active organic C/N ratio in oilseed cake was on the contrary.
基金Projects 07KJZ11 supported by the President Fund of Xuzhou Medical School07KJB310117 by the Education Department of Jiangsu Province
文摘Using the quantitative error probability density method we studied the S/N ratio of alternately sampled signals digitized by a 4-channel A/D. A complete expression for the S/N ratio of a 4-channel A/D non-uniform sampling signal was deduced. First we obtained an expression for the S/N ratio of a 1-channel A/D uniform sampling signal when the sampling frequency was equal to or greater than 2 times the frequency of the sampled signal. Based on the S/N ratio of a 2-channel A/D,alternating,non-uniform sampling signal,we analyzed the distribution of quantitative error using the quantitative error probability density method and the distribution convolution formula. From this the S/N ratio expression of a 4-channel A/D sampling signal was deduced. The simulation result shows that the deduced expression is correct.
文摘To measure the pulsed neutron of a pulsed fission source, an organic scintillation fiber （OSF） detector with separation structure has been designed. The proposed detector employs UV optical fibers as the light guide, and the sensitive region of the detector is composed of a linear array of OSFs, which are individually connected to the optical fibers. The other end of the light guide is coupled to a photomultiplier tube. The key properties of the device including the energy response, time response, neutron sensitivity, and radiation effect of the optical fiber were studied. The detector has a relatively high n/γ sensitivity ratio, which increases as the diameter of the OSF decreases, and ratios greater than 10 could be achieved when the diameter of the OSF is less than 0.3 nun. The sensitivity of the detector to neutrons ranges from 10-14 to 10-20 C cm2/n, and has a response time of 3 ns （FWHM）. The proposed detector is also highly flexible. For instance, the probe can be set close to the source, while the PMT can be placed far away from radiation, allowing easy shielding. Due to these characteristics, pulsed fission neutrons in the vicinity of the source can be accurately measured.
