基于模式搜索算法的Van Genuchten方程参数优化

针对目前Van Genuchten方程参数优化方法的不足,本文通过理论分析得出Van Genuchten方程参数的单调函数,即为单极值函数。因此,可使用局部搜索能力较强的模式搜索算法识别Van Genuchten方程参数。算例及误差分析表明:模式搜索算法求解Van Genuchten方程参数算法实现简单、运算速度快、适用性强、计算精度高,为Van Genu-chten方程参数的求解提供了一条新途径。     

天津城市绿地土壤水分特征曲线模型及参数确定

为定量评估天津城市绿地土壤水分特征曲线模型的适应性,运用张力计法获得绿地土壤水分特征曲线,选取Brooks-Corey模型、Gardner模型、Campbell模型、Van Genuchten模型、Gardner-Russo模型拟合土壤水分特征曲线,利用改进的粒子群算法确定模型参数,使用剩余平方和对模型进行评价。结果表明:Van Genuchten模型较常用的Gardner模型更好地描述天津城市绿地土壤水分特征曲线,Gardner-Russo模型模拟效果最差。通过仿真实验证明改进的粒子群算法计算土壤水分特征曲线模型参数的精度优于非单纯形法、阻尼最小二乘法、混合遗传算法以及随机粒子群算法。     

棕壤土水分特征曲线拟合的比较分析

以棕壤土为对象,采用压力膜法测定均质原状土壤样品一系列含水率和对应基质势值,分别用幂函数和Van Genuchten （1980）模型进行拟合,并与实测含水率数据进行比较。结果表明：压力膜法测定土壤水分特征曲线是可行的,所得试验结果合理,可用于土壤水分动态模拟。     

Histology of corpuscles of Stannius in Lake Van fish (Alburnus tarichi Güldenstädt, 1814) (Cyprinidae)

In the present study, the location, histology and number of corpuscles of Stannius (Sc), which are endocrine glands associated with the kidneys of teleost fish, were investigated for the first time in Lake Van fish (Alburnus tarichi), an anadromous and endemic inhabiting Turkey's Lake Van Basin. The Sc, which were ovoid or spheroid and white or cream in colour, were found to vary in number between three and five among the examined fish. The glands were located in the caudal part of the kidney, and either partially or completely embedded, and found to be present on both the ventral and dorsal surface of either side of the caudal part of the kidney. The Sc were surrounded by a connective tissue capsule that penetrated and divided the gland into incomplete lobules. Two types of cells were determined in the parenchyma of the gland. Type-I cells were predominant throughout the parenchyma and larger than the second (type-II). In the type-I cells, the cytoplasm was observed as weakly or moderately eosinophilic with haematoxylin and eosin staining and weakly or moderately acidophilic with Mallory's triple staining. In the type-I cells, the cytoplasm exhibited weak to moderate periodic acid-Schiff staining and slight or uniform staining with aldehyde fuchsin. The type-II cells were round, had a darkly stained spherical nucleus and were dispersed among the type-I cells. They displayed no cytoplasmic staining with the abovementioned stains.     

北方地区植物篱系统土壤水分特征曲线模拟与分析

以北方风沙区、黄土区、黑土区的典型植物篱为研究对象,在测定植物篱系统带内、带间部位土壤质地、土壤孔隙度、有机质含量、水稳性团聚体等指标的基础上,采用Van Genuchten模型模拟了不同地区植物篱土壤水分特征曲线。结果表明,风沙区、黑土区植物篱带内土壤孔隙度、有机质、水稳性团聚体含量均比带间高,黄土区植物篱带内土壤孔隙度、有机质、水稳性团聚体含量则比带间的低;各区域植物篱系统带内土壤含水率均比带间高,并且土壤持水力(土壤含水率)随着土壤水吸力的增大而减弱,风沙区植物篱带内、带间土壤持水力最弱,黑土区植物篱相应部位土壤持水力最高。说明植物篱具有改善土壤质地、结构,提高土壤含水率的作用,在治理坡面水土流失方面具有重要意义。     

安溪县花岗岩崩岗土体水分特征曲线及其影响因素

为研究花岗岩崩岗土体水分特征曲线及其影响因素,以福建省安溪县崩岗崩壁土为对象,通过压力膜仪对土体进行脱湿试验,绘制出崩壁土体水分特征曲线,并进行曲线参数与影响因素的相关分析。结果表明:随崩壁土体垂直深度增加,崩岗土体塑性指数、黏粒含量、分形维数及磨圆度等均整体呈降低的趋势;水分特征曲线斜率随着深度的增加而增大,土壤持水能力减弱,残余含水率及VG模型参数ɑ却随之减小,而参数n却随之增大;残余含水率、参数(ɑ、n)均与容重和颗粒的磨圆度呈极显著相关;残余含水率可用容重和黏粒含量描述,参数ɑ可用容重和形状比率描述、参数n可用容重和塑性指数描述。研究结果可为崩壁非饱和土的强度试验提供参考。     

不同质地土壤的水分特征曲线参数分析

对常用的土壤水分特征曲线模型进行了比选,选取Van Genuchten模型的4个参数进行了拟合计算,得到重壤土、中壤土、轻壤土、紧砂土和粗砂等5种不同质地土壤的水分特征曲线,分析了土壤水分特征曲线及参数的变化规律:粗砂的水分特征曲线变化最陡直,紧砂土、轻壤土、中壤土和重壤土的水分特征曲线变化较平缓;曲线的形状系数n随着粒径变大、物理性粘粒含量的减小而变大;重质粘性土壤α值较小,轻质土α值较大。     

5种砂土水分特征曲线的测试分析

为了测试分析5种砂土的水分特征曲线,运用张力计法对砾砂、粗砂、中砂、细砂、粉砂5种砂土在不同含水率下的土壤基质吸力进行实验研究,并对数据进行了三次多项式与Van Genuchten模型的拟合与验证。结果表明:细砂的水分特征曲线呈"反S"形曲线,砾砂、粗砂、中砂、粉砂呈"L"形曲线;在相同含水率条件下,5种砂土的基质吸力大小为粉砂细砂中砂粗砂砾砂;三次多项式拟合结果的R2值、PBIAS值分别为0.982 7~0.998 3、-0.119 8~0.342 7,Van Genuchten拟合结果的R2值、PBIAS值分别为0.931 0~0.992 6、-2.083 5~5.256 7,此处3次多项式拟合效果要优于Van Genuchten模型。     

Near infrared reflectance spectroscopy: A tool to characterize the composition of different types of exogenous organic matter and their behaviour in soil

In addition to total organic carbon and nitrogen, potential organic carbon mineralization under controlled laboratory conditions and indicators such as the indicator of remaining organic carbon in soil (I_ROC), based on Van Soest biochemical fractionation and short-term carbon mineralization in soil, are used to predict the evolution of exogenous organic matter (EOM) after its application to soils. The purpose of this study was to develop near infrared reflectance spectroscopy (NIRS) calibration models that could predict these characteristics in a large dataset including 300 EOMs representative of the broad range of such materials applied to cultivated soils (plant materials, animal manures, composts, sludges, etc.). The NIRS predictions of total organic matter and total organic carbon were satisfactory (R²_P = 0.80 and 0.85, ratio of performance to deviation, RPD_P = 2.2 and 2.6, respectively), and prediction of the Van Soest soluble, cellulose and holocellulose fractions were acceptable (R²_P = 0.82, 0.73 and 0.70, RPD_P = 2.3, 1.9 and 1.8, respectively) with coefficients of variation close to those of the reference methods. The NIRS prediction of carbon mineralization during incubation was satisfactory and indeed better regarding the short-term results of mineralization (R²_P = 0.78 and 0.78, and RPD_P = 2.1 and 2.0 for 3 and 7 days of incubation, respectively). The I_ROC indicator was predicted with fairly good accuracy (R²_P = 0.79, RPD_P = 2.2). Variables related to the long-term C mineralization of EOM in soil were not predicted accurately, except for I_ROC which was based on analytical and well-identified characteristics, probably because of the increasing interactions and complexity of the factors governing EOM mineralization in soil as a function of incubation time. This study demonstrated the possibility of developing NIRS predictive models for EOM characteristics in heterogeneous datasets of EOMs. However, specific NIRS predictive models still remain necessary for sludges, organo-mineral fertilizers and liquid manures.