Plant capacity for water storage leads to time lags between basal stem sap flow and transpiration in various woody plants. Internal water storage depends on the sizes of woody plants. However, the changes and its infl...Plant capacity for water storage leads to time lags between basal stem sap flow and transpiration in various woody plants. Internal water storage depends on the sizes of woody plants. However, the changes and its influencing factors in time lags of basal stem flow during the development of herbaceous plants including crops remain unclear. A field experiment was conducted in an arid region of Northwest China to examine the time lag characteristics of sap flow in seed-maize and to calibrate the transpiration modeling. Cross-correlation analysis was used to estimate the time lags between stem sap flow and meteorological driving factors including solar radiation（R_s） and vapor pressure deficit of the air（VPD_（air））. Results indicate that the changes in seed-maize stem sap flow consistently lagged behind the changes in R_s and preceded the changes in VPD_（air） both on hourly and daily scales, suggesting that light-mediated stomatal closures drove sap flow responses. The time lag in the maize＇s sap flow differed significantly during different growth stages and the difference was potentially due to developmental changes in capacitance tissue and/or xylem during ontogenesis. The time lags between stem sap flow and R_s in both female plants and male plants corresponded to plant use of stored water and were independent of total plant water use. Time lags of sap flow were always longer in male plants than in female plants. Theoretically, dry soil may decrease the speed by which sap flow adjusts ahead of shifts in VPD_（air） in comparison with wet soil and also increase the speed by which sap flow adjusts to R_s. However, sap flow lags that were associated with R_s before irrigation and after irrigation in female plants did not shift. Time series analysis method provided better results for simulating seed-maize sap flow with advantages of allowing for fewer variables to be included. This approach would be helpful in improving the accuracy of estimation for canopy transpiration and conductance using meteorological measurements.展开更多
An anisotropic continuum stored energy (CSE), which is essentially composed of invariant component groups (ICGs), is postulated to be balanced with its stress work done, constructing a partial differential equation (P...An anisotropic continuum stored energy (CSE), which is essentially composed of invariant component groups (ICGs), is postulated to be balanced with its stress work done, constructing a partial differential equation (PDE). The anisotropic CSE PDE is generally solved by the Lie group and the ICGs through curvatures of elasticity tensor are particularly grouped by differential geometry, representing three general deformations: preferred translational deformations, preferred rotational deformations, and preferred powers of ellipsoidal deformations. The anisotropic CSE constitutive models have been curve-fitted for uniaxial tension tests of rabbit abdominal skins and porcine liver tissues, and biaxial tension and triaxial shear tests of human ventricular myocardial tissues. With the newly defined second invariant component, the anisotropic CSE constitutive models capture the transverse effects in uniaxial tension deformations and the shear coupling effects in triaxial shear deformations.展开更多
In Karst drainage basins, there are the ground water and underground water exchanging frequently, and the shortage of water resources due to having the special double aquifer mediums and unique surface and subsurface ...In Karst drainage basins, there are the ground water and underground water exchanging frequently, and the shortage of water resources due to having the special double aquifer mediums and unique surface and subsurface river systematic structure. This paper is to select 20 research sampling areas coming fromGuizhouProvince, and according to the spectral characteristics of the catchment water-holding mediums and vegetations, and using the remote sensing technique, extract the watershed vegetation index. According to the principle of principal component analysis, using the software of Spss and Matlab is to analyze the impacts of watershed vegetation type on the catchment water-holding ability, and establish the principal component analysis function. Studies have shown that: 1) the watershed vegetation coverage rate plays an important role in Karst basin water-holding ability;2) the catchment water-holding ability is the comprehensive reflection and manifestation of the Catchment Water-storing Capacity (CWC);3) it is much better effects and higher accuracy to monitor/forecast the catchment water-holding volume by using the vegetation indices.展开更多
The partial differential equation for isotropic hyperelastic constitutive models has been postulated and derived from the balance between stored energy and stress work done. The partial differential equation as a func...The partial differential equation for isotropic hyperelastic constitutive models has been postulated and derived from the balance between stored energy and stress work done. The partial differential equation as a function of three invariants has then been solved by Lie group methods. With geometric meanings of deformations, the general solution boils down to a particular three-term solution. The particular solution has been applied for several isotropic hyperelastic materials. For incompressible materials, vulcanized rubber containing 8% sulfur and Entec Enflex S4035A thermoplastic elastomer, three coefficients have been determined from uniaxial tension data and applied to predict the pure shear and equibiaxial tension modes. For a slightly compressible rubber material, the coefficients have also been extracted from the confined volumetric test data.展开更多
储粮害虫是影响粮食安全的重要因素,深入研究储粮害虫事件的发展过程及其因果关系极为关键。通过量化分析储粮害虫事件之间的因果强度,能够更加准确地评估潜在风险,帮助相关工作人员制定防控措施,减少不必要的损失。为解决储粮害虫领域...储粮害虫是影响粮食安全的重要因素,深入研究储粮害虫事件的发展过程及其因果关系极为关键。通过量化分析储粮害虫事件之间的因果强度,能够更加准确地评估潜在风险,帮助相关工作人员制定防控措施,减少不必要的损失。为解决储粮害虫领域数据中存在的数据偏差而造成模型过分依赖数据集中的表面特征,在应对泛化数据时效果不佳的问题,该研究提出一种反事实数据增强的因果强度计算方法,旨在准确量化事件之间的因果强度。设计了一个反事实数据增强的因果强度计算框架(counterfactual data augmentation-event causal strength,CDA-ECS),通过利用大语言模型(large language model,LLM)生成反事实实例,对原始数据进行扩展,将去偏的因果知识整合进预训练语言模型中,帮助其更深入地理解和学习句子的因果关系,提高模型的泛化能力。在公共数据集和领域数据集上的试验表明,所提方法能够训练出更加稳健的模型,在领域泛化数据的推理任务上准确率提高了2.4个百分点,能有效应用于储粮害虫事件的因果强度计算。在储粮害虫领域,反事实数据增强方法的引入为解决数据偏差提供了一种新的视角,增强后数据的多样性和复杂性使得模型能够更加深入地理解害虫行为与环境因素之间的复杂联系,进一步帮助实现储粮害虫事件的风险分析。该研究证明了反事实数据增强方法的可行性和有效性,为实现储粮害虫事件的因果强度计算提供了一定的参考。展开更多
文摘利用可见-近红外光谱建立多品种模型以实现快速无损检测猕猴桃贮藏时的内部品质。以‘海沃德’‘金桃’和‘徐香’猕猴桃为实验对象,测定不同贮藏时间下硬度、可溶性固形物、可滴定酸和果肉颜色的变化规律,采集592~1102 nm波长范围内的光谱数据,采用一阶导数(first-order derivatives,FD)、标准正态变量变换(standard normal variate,SNV)、二阶导数、卷积平滑以及FD+SNV的预处理算法,结合竞争性自适应重加权采样法(competitive adaptive reweighted sampling,CARS)进行特征波长选择,建立基于偏最小二乘(partial least squares,PLS)和多元线性回归(multiple linear regression,MLR)的猕猴桃理化指标的品质预测模型。结果表明,FD和SNV预处理后的模型预测精度最高,单一品种模型SSC的相对预测偏差(relative prediction deviation,RPD)均高于2.3,除‘徐香’硬度RPD为1.8外,其他品种硬度RPD也高于2.3;采用CARS提取出600~700、930~990、1000~1100 nm是相关度较高的特征波段;各指标PLS模型的预测结果相对优于MLR模型;建立混合品种通用模型得到FD+SNV结合预处理后的预测性能显著提高,SSC、TA和a*模型的RPD分别为2.280、2.183和3.425,相较于单一品种的模型准确性更好。综上,利用可见-近红外光谱技术能够用于猕猴桃贮藏品质的定量检测,为猕猴桃的无损检测技术应用提供了依据和参考。
基金国家自然科学基金项目“Empirical analysis and forecasting of time-varying parameters and flexible error structurevector autoregressive models in the context of big data”(项目编号:72250410372)温州市社会科学重点研究基地项目“长三角地区经济一体化与高质量发展的大数据宏观经济模型构建、预测与风险防范”(项目编号:22JD30)。
基金support from the National Key Basic Research Program of China (2016YFC0400207)the National Natural Science Foundation of China (51439006, 91425302)the 111 Program of Introducing Talents of Discipline to Universities (B14002)
文摘Plant capacity for water storage leads to time lags between basal stem sap flow and transpiration in various woody plants. Internal water storage depends on the sizes of woody plants. However, the changes and its influencing factors in time lags of basal stem flow during the development of herbaceous plants including crops remain unclear. A field experiment was conducted in an arid region of Northwest China to examine the time lag characteristics of sap flow in seed-maize and to calibrate the transpiration modeling. Cross-correlation analysis was used to estimate the time lags between stem sap flow and meteorological driving factors including solar radiation（R_s） and vapor pressure deficit of the air（VPD_（air））. Results indicate that the changes in seed-maize stem sap flow consistently lagged behind the changes in R_s and preceded the changes in VPD_（air） both on hourly and daily scales, suggesting that light-mediated stomatal closures drove sap flow responses. The time lag in the maize＇s sap flow differed significantly during different growth stages and the difference was potentially due to developmental changes in capacitance tissue and/or xylem during ontogenesis. The time lags between stem sap flow and R_s in both female plants and male plants corresponded to plant use of stored water and were independent of total plant water use. Time lags of sap flow were always longer in male plants than in female plants. Theoretically, dry soil may decrease the speed by which sap flow adjusts ahead of shifts in VPD_（air） in comparison with wet soil and also increase the speed by which sap flow adjusts to R_s. However, sap flow lags that were associated with R_s before irrigation and after irrigation in female plants did not shift. Time series analysis method provided better results for simulating seed-maize sap flow with advantages of allowing for fewer variables to be included. This approach would be helpful in improving the accuracy of estimation for canopy transpiration and conductance using meteorological measurements.
文摘An anisotropic continuum stored energy (CSE), which is essentially composed of invariant component groups (ICGs), is postulated to be balanced with its stress work done, constructing a partial differential equation (PDE). The anisotropic CSE PDE is generally solved by the Lie group and the ICGs through curvatures of elasticity tensor are particularly grouped by differential geometry, representing three general deformations: preferred translational deformations, preferred rotational deformations, and preferred powers of ellipsoidal deformations. The anisotropic CSE constitutive models have been curve-fitted for uniaxial tension tests of rabbit abdominal skins and porcine liver tissues, and biaxial tension and triaxial shear tests of human ventricular myocardial tissues. With the newly defined second invariant component, the anisotropic CSE constitutive models capture the transverse effects in uniaxial tension deformations and the shear coupling effects in triaxial shear deformations.
文摘In Karst drainage basins, there are the ground water and underground water exchanging frequently, and the shortage of water resources due to having the special double aquifer mediums and unique surface and subsurface river systematic structure. This paper is to select 20 research sampling areas coming fromGuizhouProvince, and according to the spectral characteristics of the catchment water-holding mediums and vegetations, and using the remote sensing technique, extract the watershed vegetation index. According to the principle of principal component analysis, using the software of Spss and Matlab is to analyze the impacts of watershed vegetation type on the catchment water-holding ability, and establish the principal component analysis function. Studies have shown that: 1) the watershed vegetation coverage rate plays an important role in Karst basin water-holding ability;2) the catchment water-holding ability is the comprehensive reflection and manifestation of the Catchment Water-storing Capacity (CWC);3) it is much better effects and higher accuracy to monitor/forecast the catchment water-holding volume by using the vegetation indices.
文摘The partial differential equation for isotropic hyperelastic constitutive models has been postulated and derived from the balance between stored energy and stress work done. The partial differential equation as a function of three invariants has then been solved by Lie group methods. With geometric meanings of deformations, the general solution boils down to a particular three-term solution. The particular solution has been applied for several isotropic hyperelastic materials. For incompressible materials, vulcanized rubber containing 8% sulfur and Entec Enflex S4035A thermoplastic elastomer, three coefficients have been determined from uniaxial tension data and applied to predict the pure shear and equibiaxial tension modes. For a slightly compressible rubber material, the coefficients have also been extracted from the confined volumetric test data.
文摘储粮害虫是影响粮食安全的重要因素,深入研究储粮害虫事件的发展过程及其因果关系极为关键。通过量化分析储粮害虫事件之间的因果强度,能够更加准确地评估潜在风险,帮助相关工作人员制定防控措施,减少不必要的损失。为解决储粮害虫领域数据中存在的数据偏差而造成模型过分依赖数据集中的表面特征,在应对泛化数据时效果不佳的问题,该研究提出一种反事实数据增强的因果强度计算方法,旨在准确量化事件之间的因果强度。设计了一个反事实数据增强的因果强度计算框架(counterfactual data augmentation-event causal strength,CDA-ECS),通过利用大语言模型(large language model,LLM)生成反事实实例,对原始数据进行扩展,将去偏的因果知识整合进预训练语言模型中,帮助其更深入地理解和学习句子的因果关系,提高模型的泛化能力。在公共数据集和领域数据集上的试验表明,所提方法能够训练出更加稳健的模型,在领域泛化数据的推理任务上准确率提高了2.4个百分点,能有效应用于储粮害虫事件的因果强度计算。在储粮害虫领域,反事实数据增强方法的引入为解决数据偏差提供了一种新的视角,增强后数据的多样性和复杂性使得模型能够更加深入地理解害虫行为与环境因素之间的复杂联系,进一步帮助实现储粮害虫事件的风险分析。该研究证明了反事实数据增强方法的可行性和有效性,为实现储粮害虫事件的因果强度计算提供了一定的参考。
