Due to its rapid growth and high rate of spread, Phyllostachys pubescens can suppress other species, eventually leading to pure P. pubescens forests. Research on the patterns of litter decomposition and nutrient relea...Due to its rapid growth and high rate of spread, Phyllostachys pubescens can suppress other species, eventually leading to pure P. pubescens forests. Research on the patterns of litter decomposition and nutrient release from P. pubescens across stand mixtures are helpful to understand the decomposition and nutrient dynamics during the invasion process. However, little is known for unmanaged conditions at high elevations. Therefore, we studied the decomposition of four litter compositions comprised of different combinations of P. pubescens and Cunninghamia lanceolata foliage for one year to explore the pattern of litter decomposition and nutrient release at the Daiyun Mountain National Nature Reserve. The results show that:(1) the litter decomposed faster with a higher proportion of P. pubescens based on Olson's decay model;(2) the remaining litter compositions followed a trigonometric function model better than Olson'sdecay model and fluctuated periodically in tandem with changing temperature and precipitation;(3) the litter mixture decompositions did not support the biomass-ratio hypothesis test; and(4) there were significant binomial, power and exponential relationships between initial concentration and final amounts remaining after 1 year decomposition for C, N and P. The correlations between litter decomposition and nutrient releases were significant. The results may be used to explain the rapid spread of P. pubescens and to guide the natural management of plantations.展开更多
The fate of the litter of dominant vegetation(willows and reeds) is one of the aspects studied in the frame of the project “Onderzoek Milieu Effecten Sigmaplan”. One of the questions to be considered is how long the...The fate of the litter of dominant vegetation(willows and reeds) is one of the aspects studied in the frame of the project “Onderzoek Milieu Effecten Sigmaplan”. One of the questions to be considered is how long the litter stays within the estuary. In this paper, the time the leaf litter(Salix triandra and Phragmites australis) stayed in the Schelde estuary was studied by using plant pigment as biomarkers with HPLC application. After analyzing the original data from the incubation experiment described by Dubuison and Geers(1999), the decomposition dynamics patterns of pigments were analyzed and described, and these decomposition dynamics patterns were used as calibration patterns. By using Spearman Rank Order Correlation, the calibration patterns of the pigments which were significant(p<0.05) were grouped. In this way, several groups of the calibration patterns of pigment decomposition were achieved. The presence or absence of these groups of pigments (whether they can be detected or not from HPLC) was shown to be useful in determining the time the litter has stayed in the water. Combining data of DW and POC, more precise timing can be obtained.展开更多
Grain boundary directed spinodal decomposition has a substantial effect on the microstructure evolution and properties of polycrystalline alloys.The morphological selection mechanism of spinodal decomposition at grain...Grain boundary directed spinodal decomposition has a substantial effect on the microstructure evolution and properties of polycrystalline alloys.The morphological selection mechanism of spinodal decomposition at grain boundaries is a major challenge to reveal,and remains elusive so far.In this work,the effect of grain boundaries on spinodal decomposition is investigated by using the phase-field model.The simulation results indicate that the spinodal morphology at the grain boundary is anisotropic bicontinuous microstructures different from the isotropic continuous microstructures of spinodal decomposition in the bulk phase.Moreover,at grain boundaries with higher energy,the decomposed phases are alternatingα/βlayers that are parallel to the grain boundary.On the contrary,alternatingα/βlayers are perpendicular to the grain boundary.展开更多
提高作物水分生产力(Crop Water Productivity,CWP)是减少农业用水、实现可持续发展的重要途径,掌握CWP的时空特征则是通过管理生产和耗水提高CWP的重要前提。本文综合作物遥感蒸散数据和农业生产数据,分析了鲁西平原冬小麦CWP的时空格...提高作物水分生产力(Crop Water Productivity,CWP)是减少农业用水、实现可持续发展的重要途径,掌握CWP的时空特征则是通过管理生产和耗水提高CWP的重要前提。本文综合作物遥感蒸散数据和农业生产数据,分析了鲁西平原冬小麦CWP的时空格局,并利用因素分解方法探讨了单产和蒸散对CWP变化的直接贡献。结果表明:2002年以来,鲁西平原冬小麦单产显著提高(P<0.05),推动冬小麦总产稳步提升,但2010年以后,单产贡献量逐渐减弱。2010年以后,种植面积具有正向效应(种植面积增加、总产增加,或种植面积减少、总产减少)的县域数目呈减少趋势。2006年以后,鲁西平原冬小麦CWP显著增加(P<0.05),2016年达到1.64 kg/m^(3)。空间分布特征表明,德州和济宁是CWP较高的“热点”地区。冬小麦CWP的变化直接受单产和蒸散的影响,2010年以后,单产具有正向效应(单产增加、CWP增加,或单产减少、CWP减少)的县域数量减少,蒸散具有正向效应(蒸散增加、CWP减少,或蒸散减少、CWP增加)的县域数目维持在较高水平,蒸散在CWP变化中起着越来越重要的作用。在单产增长趋于平缓的现状下,通过管理蒸散成为提升鲁西平原冬小麦CWP的重要途径,但也需要进一步挖掘单产的提升潜力。本研究可为鲁西平原冬小麦生产和耗水管理决策提供参考。展开更多
Gas–liquid two-phase flow abounds in industrial processes and facilities. Identification of its flow pattern plays an essential role in the field of multiphase flow measurement. A bluff body was introduced in this s...Gas–liquid two-phase flow abounds in industrial processes and facilities. Identification of its flow pattern plays an essential role in the field of multiphase flow measurement. A bluff body was introduced in this study to recognize gas–liquid flow patterns by inducing fluid oscillation that enlarged differences between each flow pattern. Experiments with air–water mixtures were carried out in horizontal pipelines at ambient temperature and atmospheric pressure. Differential pressure signals from the bluff-body wake were obtained in bubble, bubble/plug transitional, plug, slug, and annular flows. Utilizing the adaptive ensemble empirical mode decomposition method and the Hilbert transform, the time–frequency entropy S of the differential pressure signals was obtained. By combining S and other flow parameters, such as the volumetric void fraction β, the dryness x, the ratio of density φ and the modified fluid coefficient ψ, a new flow pattern map was constructed which adopted S（1–x）φ and （1–β）ψ as the vertical and horizontal coordinates, respectively. The overall rate of classification of the map was verified to be 92.9% by the experimental data. It provides an effective and simple solution to the gas–liquid flow pattern identification problems.展开更多
基金The Projects is jointly supported by National Natural Science Foundation of China and Civil Aviation Administration of China [U1433118], also jointly supported by Hunan Provincial Natural Science Foundation of China and Xiangtan Municipal Science and Technology Bureau [ 14J J5011 ].
基金funded by the Fujian Provincial Education Department (Grants No. JA15154)Youth Foundation of Fujian Agriculture and Forestry University (Grants No. 2010007)
文摘Due to its rapid growth and high rate of spread, Phyllostachys pubescens can suppress other species, eventually leading to pure P. pubescens forests. Research on the patterns of litter decomposition and nutrient release from P. pubescens across stand mixtures are helpful to understand the decomposition and nutrient dynamics during the invasion process. However, little is known for unmanaged conditions at high elevations. Therefore, we studied the decomposition of four litter compositions comprised of different combinations of P. pubescens and Cunninghamia lanceolata foliage for one year to explore the pattern of litter decomposition and nutrient release at the Daiyun Mountain National Nature Reserve. The results show that:(1) the litter decomposed faster with a higher proportion of P. pubescens based on Olson's decay model;(2) the remaining litter compositions followed a trigonometric function model better than Olson'sdecay model and fluctuated periodically in tandem with changing temperature and precipitation;(3) the litter mixture decompositions did not support the biomass-ratio hypothesis test; and(4) there were significant binomial, power and exponential relationships between initial concentration and final amounts remaining after 1 year decomposition for C, N and P. The correlations between litter decomposition and nutrient releases were significant. The results may be used to explain the rapid spread of P. pubescens and to guide the natural management of plantations.
文摘The fate of the litter of dominant vegetation(willows and reeds) is one of the aspects studied in the frame of the project “Onderzoek Milieu Effecten Sigmaplan”. One of the questions to be considered is how long the litter stays within the estuary. In this paper, the time the leaf litter(Salix triandra and Phragmites australis) stayed in the Schelde estuary was studied by using plant pigment as biomarkers with HPLC application. After analyzing the original data from the incubation experiment described by Dubuison and Geers(1999), the decomposition dynamics patterns of pigments were analyzed and described, and these decomposition dynamics patterns were used as calibration patterns. By using Spearman Rank Order Correlation, the calibration patterns of the pigments which were significant(p<0.05) were grouped. In this way, several groups of the calibration patterns of pigment decomposition were achieved. The presence or absence of these groups of pigments (whether they can be detected or not from HPLC) was shown to be useful in determining the time the litter has stayed in the water. Combining data of DW and POC, more precise timing can be obtained.
基金Project supported by the National Natural Science Foundation of China(Grant No.51801154)the Fund from the State Key Laboratory of Solidification Processing in Northwestern Polytechnical University,China(Grant No.SKLSP201813)the Shaanxi Provincial Science Fund for Distinguished Young Scholars,China(Grant No.2018JC-027).
文摘Grain boundary directed spinodal decomposition has a substantial effect on the microstructure evolution and properties of polycrystalline alloys.The morphological selection mechanism of spinodal decomposition at grain boundaries is a major challenge to reveal,and remains elusive so far.In this work,the effect of grain boundaries on spinodal decomposition is investigated by using the phase-field model.The simulation results indicate that the spinodal morphology at the grain boundary is anisotropic bicontinuous microstructures different from the isotropic continuous microstructures of spinodal decomposition in the bulk phase.Moreover,at grain boundaries with higher energy,the decomposed phases are alternatingα/βlayers that are parallel to the grain boundary.On the contrary,alternatingα/βlayers are perpendicular to the grain boundary.
文摘提高作物水分生产力(Crop Water Productivity,CWP)是减少农业用水、实现可持续发展的重要途径,掌握CWP的时空特征则是通过管理生产和耗水提高CWP的重要前提。本文综合作物遥感蒸散数据和农业生产数据,分析了鲁西平原冬小麦CWP的时空格局,并利用因素分解方法探讨了单产和蒸散对CWP变化的直接贡献。结果表明:2002年以来,鲁西平原冬小麦单产显著提高(P<0.05),推动冬小麦总产稳步提升,但2010年以后,单产贡献量逐渐减弱。2010年以后,种植面积具有正向效应(种植面积增加、总产增加,或种植面积减少、总产减少)的县域数目呈减少趋势。2006年以后,鲁西平原冬小麦CWP显著增加(P<0.05),2016年达到1.64 kg/m^(3)。空间分布特征表明,德州和济宁是CWP较高的“热点”地区。冬小麦CWP的变化直接受单产和蒸散的影响,2010年以后,单产具有正向效应(单产增加、CWP增加,或单产减少、CWP减少)的县域数量减少,蒸散具有正向效应(蒸散增加、CWP减少,或蒸散减少、CWP增加)的县域数目维持在较高水平,蒸散在CWP变化中起着越来越重要的作用。在单产增长趋于平缓的现状下,通过管理蒸散成为提升鲁西平原冬小麦CWP的重要途径,但也需要进一步挖掘单产的提升潜力。本研究可为鲁西平原冬小麦生产和耗水管理决策提供参考。
基金Project(51576213)supported by the National Natural Science Foundation of ChinaProject(2015RS4015)supported by the Hunan Scientific Program,ChinaProject(2016zzts323)supported by the Innovation Project of Central South University,China
文摘Gas–liquid two-phase flow abounds in industrial processes and facilities. Identification of its flow pattern plays an essential role in the field of multiphase flow measurement. A bluff body was introduced in this study to recognize gas–liquid flow patterns by inducing fluid oscillation that enlarged differences between each flow pattern. Experiments with air–water mixtures were carried out in horizontal pipelines at ambient temperature and atmospheric pressure. Differential pressure signals from the bluff-body wake were obtained in bubble, bubble/plug transitional, plug, slug, and annular flows. Utilizing the adaptive ensemble empirical mode decomposition method and the Hilbert transform, the time–frequency entropy S of the differential pressure signals was obtained. By combining S and other flow parameters, such as the volumetric void fraction β, the dryness x, the ratio of density φ and the modified fluid coefficient ψ, a new flow pattern map was constructed which adopted S（1–x）φ and （1–β）ψ as the vertical and horizontal coordinates, respectively. The overall rate of classification of the map was verified to be 92.9% by the experimental data. It provides an effective and simple solution to the gas–liquid flow pattern identification problems.
