辽宁省沈阳样区土系的划分

本文在对沈阳样区进行广泛调查的基础上 ,对约 10 0个土壤剖面进行了详细观测、描述 ,对 14个典型土壤剖面进行了取样、分析和比较 ,探讨了土族和土系划分的原则与依据 ,并在样区建立了 14个土系     

武汉市典型地区土系的研究

本文以典型区土壤详查和环境研究为基础 ,采用《中国土壤系统分类》(修订方案 1 995)的标准划分了土壤的高级分类单元 ;探讨了土系的划分原则、依据及土系的描述方法 ,并拟定了区域土系检索系统 .为土系的研究和土系制的应用提供范例     

成都平原主要水耕人为土土系的划分研究

本文以成都平原主要水耕人为土为例,在中国土壤系统分类思想的指导下,通过典型采样、土壤详查、环境调查和室内理化分析,按照土系划分指标的稳定性、差异性、主导性及综合性等原则,对样区水耕人为土的土系进行了具体划分研究。     

湿润淋溶土、雏形土系统分类的参比

在北亚热带的汉中、南阳、南京选取了十个代表性土壤剖面 ,分析其理化性质 ,鉴定了诊断层和诊断特征 ,并对其在中国土壤系统分类、美国土壤系统分类、世界土壤图图例单元和土壤发生分类制的类型进行参比 .     

安徽休屯盆地紫色土的特性和系统分类

选取了休屯盆地不同时期紫红色沉积岩上发育的 6个紫色土剖面 ,系统地研究了其属性特征 ,并按照中国土壤系统分类的原则 ,鉴定其诊断层和诊断特性 ,检索了土壤系统分类的名称。同时也指出了现行《中国土壤系统分类》在紫色土系统分类应用中存在的问题 ,分析了其原因并提出修订建议     

豫南白浆化黄褐土分类参比研究

根据土壤理化性质,分别按照《中国土壤系统分类(第三版)》中的诊断层和诊断特性和中国土壤分类系统的发生分类原则对河南省南部地区具有漂白层的4个代表性土壤剖面进行分类归属,确定其在中国土壤系统分类中属于淋溶土纲,湿润淋溶土亚纲、漂白湿润淋溶土土类及相应的亚类、土族、土系;在中国土壤分类系统中属于湿暖淋溶土亚纲,黄褐土土类,白浆化黄褐土亚类及相应的土属、土种。     

关于土系制图的原则和方法——以安徽宣郎广样区为例

本文根据土壤系统分类的要求 ,提出了土系制图单元划分的原则和方法 ,并谈了在安徽宣郎广样区实验中的一些体会。     

辽宁潮湿碱积盐成土系统分类的研究

本文选用了过去土壤发生命名的6个碱化土壤剖面，对照《中国土壤系统分类(修订方案)》诊断指标加以鉴验，确定在系统分类中的地位，并对诊断指标和类型提出了修改和建议.     

台湾土壤管理组研究的有关进展

介绍了台湾学者为了公众使用方便,所建立的新土壤管理组系统。从土壤管理与改良土壤肥力的角度,选择适当的标准合并全省的土系,这些标准包括土壤深度、土壤质地、排水等级和土壤反应等4种辨别土系特征且在野外容易判断的重要土壤性质。通过研究,把全省924笔土系资料,最后归并为45个土壤管理组,并且认为可以根据当地的环境、气候特征、农作物种植面积多寡,做进一步的合并,以求土地利用的完整性与培肥管理上的方便。     

南疆灌耕棕漠土的基层分类

本文分析了南疆西部莎车县和东部哈密县灌耕棕漠土的成土条件,探讨了灌耕棕漠土的系统分类,特别是基层分类,根据南疆灌耕棕漠土的实际情况,结合11个剖面,讨论了土族和土系的划分依据和指标,描述了各土系的生产特性。     

几种稻田土壤对铵的矿物固定的动力学与热力学研究

本文采用振荡平衡法研究了紫泥田、河沙泥、灰泥田及红黄泥4种稻田土壤对铵的矿物固定的动力学及热力学特性。结果表明,供试土壤对添加铵的矿物固定速度很快,随着固铵量增多,固铵速度下降,反应后24小时固定基本上达到平衡,不因土壤种类而异。数学拟合结果表明,以一级动力学方程和E lovich方程描述供试土壤对铵的矿物固定资料最优,抛物扩散方程也能较满意地描述实验结果,以零级方程的拟合效果最差。供试土壤对铵的矿物固定的热力学资料均能用一元Langmu ir吸附等温式、Freund lich吸附等温式和Temk in吸附等温式拟合,拟合结果均达极显著水平,但以一元Langmu ir吸附等温式的拟合结果最优,由一元Langmu ir吸附等温式可以求得土壤对铵的矿物固定的热力学平衡常数、最大固铵量以及固铵过程中的自由能变△G°。供试土壤固铵过程的自由能变△G°均为负值,说明供试土壤对铵的矿物固定为一自发过程,4种土壤固铵强度依次为紫泥田>河沙泥>灰泥田>红黄泥。     

磷钾硼锌肥对百合、白术产量和养分吸收的影响

在田间试验条件下研究了不同营养元素对百合、白术产量和养分吸收的影响。两年结果表明,在河沙土和灰泥土上,施用磷、钾、硼和锌肥的百合产量分别平均增产5.1%、33.5%、22.3%、16.3%和16.2%、12.5%、2.1%、6.1%,在灰泥土上,白术产量分别平均增产8.6%、34.6%、9.1%、5.8%,百合施用钾、硼和锌肥的增产效果大于白术,而白术施磷的增产效果大于百合。施磷肥能促进百合和白术对氮、磷、钾和硼的吸收,而降低对锌的吸收;施钾、硼和锌肥能增进百合和白术的氮、磷、钾、硼和锌养分的吸收量。百合和白术吸收的养分量表现出钾>磷>锌>硼。百合和白术吸收的氮、磷、钾和锌主要分配在鳞茎和根状茎部分,吸收的硼主要集中在茎叶部分。平衡施肥可提高药用部分(鳞茎和根状茎)的磷、钾和锌养分的分配比率。     

Detection of sandy soil surfaces using ASTER‐derived reflectance,emissivity and elevation data: potential for the identification of land degradation

Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) reflectance and emissivity data were used to discriminate nonphotosynthetic vegetation (NPV) from exposed soils, to produce a topsoil texture image, and to relate sand fraction estimates with elevation data in an agricultural area of central Brazil. The results show that the combination of the shortwave infrared (SWIR) bands 5 and 6 (hydroxyl absorption band) and thermal infrared (TIR) bands 10 and 14 (quartz reststrahlen feature) discriminated dark red clayey soils and bright sandy soils from NPV (crop litter), respectively. The ratio of the bands 10 and 14 was correlated with laboratory measured total sand fraction. When applied to the image and associated with topography, a predominance of sandy soil surfaces at lower elevations and clayey soil surfaces at higher elevations was observed. Areas presenting the largest sand fraction values, identified from ASTER band 10/14 emissivity ratio, were coincident with land degradation processes.     

亚热带小流域不同沉积区土壤粘粒矿物的演变

在亚热带丘陵河谷地小流域范围内地表物质的迁移常可导致不同沉积区物质组成的变化 .从黄泥土→洪积泥砂土→培泥砂土 ,随着搬运距离的增加 ,其粘粒矿物组成发生了一系列的变化 ;高岭石逐渐下降 ,云母逐渐增加 ,蛭石渐趋下降消失 ,而绿泥石则逐渐形成 ;同时赤铁矿、针铁矿也先后下降消失 .矿物的演化与沉积物所处环境的水分条件及溶液中盐基物质和酸碱度变化有关     

Estimation of pressuremeter modulus and limit pressure of clayey soils by various artificial neural network models

The main purpose of the present study is to develop some artificial neural network (ANN) models for the prediction of limit pressure (P _L) and pressuremeter modulus (E _M) for clayey soils. Moisture content, plasticity index, and SPT values are used as inputs in the ANN models. To get plausible results, the number of hidden layer neurons in all models is varied between 1 and 5. In addition, both linear and nonlinear activation functions are considered for the neurons in output layers while a nonlinear activation function is employed for the neurons in the hidden layers of all models. Logistic activation function is used as a nonlinear activation function. During the modeling studies, total eight different ANN models are constructed. The ANN models having two outputs produced the worst results, independent from activation function. However, for P _L, the best results are obtained from the feed-forward neural network with five neurons in the hidden layer, and logistic activation function is employed in the output neuron. For E _M, the best model producing the most acceptable results is Elman recurrent network model, which has 4 neurons in the neurons in the hidden layer, and linear activation function is used for the output neuron. Finally, the results show that the ANN models produce the more accurate results than the regression-based models. In the literature, when empirical equations based on regression analysis were used, the best root mean square error (RMSE) values obtained to date for P _L and E _M have been 0.43 and 5.65, respectively. In this study, RMSE values for P _L and E _M were found to be 0.20 and 2.99, respectively, by using ANN models. It was observed that using ANN approach drastically increases the prediction accuracy in terms of RMSE criterion.     

Using a MODFLOW grid, generated with GMS, to solve a transport problem with TOUGH2 in complex geological environments: The intertidal deposits of the Venetian Lagoon

The tides of the Venetian Lagoon generally vary between −0.5 and +0.7 m asl. Occasionally, they may reach a maximum of 1.5 m (acqua alta) and a minimum of −0.8 m asl (acqua bassa). Intertidal areas, called “barene,” exist all along the coast of the Lagoon. These areas are characterized by canals that concentrate the flow of water (and the deposition of sands) during the rising and waning of the tides, and that inundate and drain the vegetated areas found between canals (where organic-rich clays are deposited). Therefore, since the area is subject to subsidence, in time, sand dykes (the original canals) become juxtaposed to clayey dykes (the original vegetated areas). In addition, the sands form a continuous hydrogeologic network within the clays, very similar to that of a vascular system that effectively drains the whole “barena” deposits. In order to be effective, measures for monitoring, confining, or remediating the transport of pollutants through this kind of environment must explicitly take into account the geologic complexity. The same complexity must be included in the numerical models that support remediation efforts. At the moment, there appears to be no off-the-shelf graphical interface that is able to manage such complexity for TOUGH2. To attempt to solve this problem we have used a calibrated USGS-MODFLOW model, of the barena of “Passo a Campalto” in the Venetian Lagoon, developed with the GMS graphical interface. The model is made of 42 layers, which, apart from the first layer, are 0.5 m thick; the first layer has the thickness distribution of a dump found on top of the barena deposit at Passo a Campalto. Each layer consists of 100×60 square cells, for a total of 252,000 cells, only about half of which are active. Using a FORTRAN routine, we translate this grid, with all the hydrogeologic boundary conditions, into a TOUGH2 input file, and we provide the additional necessary information for running a TOUGH2 simulation. The results are promising, in that we were able to produce TOUGH2 grids with very complex geology and to run the models with success. For visualization, the results can be imported back into GMS as 3D scatter point sets, or they can be plotted with any adequate plotting software such as MatLab. Developing conceptual and numerical models with an elaborate graphical interface such as GMS effectively allows setting up complex problems while concentrating on their physics.     

Surface-sediment dynamics in a dust source from spaceborne multispectral thermal infrared data

This study utilized spaceborne multispectral thermal infrared (TIR) data to document spatial relationships of surface sediments over time in a modern depositional environment associated with dust emissions, Soda Lake playa, Mojave Desert, United States. The approach employed here involved time-series TIR data acquired from Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) and a linear spectral mixture analysis. An automated algorithm was applied to derive emissivity image endmembers. Evaluation of the chosen endmembers revealed that they can be categorized into five major spectra classes based on diagnostic absorption features. Each spectrum has been identified in relation to mineral abundance and soil arrangement that are common in playa settings: A, “clayey silt-rich crust”; B, “intermediate-salt crust”; C, “quartz-rich deposit”; D, “salt-rich rough crust”; E, “sulfate-rich crust”. Spectral classes A-B-C-D yielded the lowest RMS errors (0-0.025) over time in the iterative deconvolution algorithm between the measured and modeled spectra. The produced fractional abundance images show high areal concentrations for clayey silt-rich crust, salt-rich rough crust, and quartz-rich deposit, as the first surficial mapping of Soda Lake. Significant changes in the spatial relationships of the major surface sediments in Soda Lake were observed after a flooding event (2005) and a relatively dry period (2006). The approach utilized in this study can be advantageous for continuous monitoring of environments characterized by a small area and a complex surface, which may enable a better understanding of their responses to climate changes and potential for dust emissions.     

层次化WebGIS构件系统的设计与实现

给出了一个实用的WebGIS对象构件系统模型Geo Union .它由 4个层次组成 :存储层、服务层、构件层和应用层 ,其中服务层又可分为客户端和服务器两个层面 .详细论述了Geo Union各层的结构、对象组成以及相互之间的关系 ,并对Geo Union中所采取的关键技术———空间数据模型、ORDB、空间索引以及空间缓存等进行了总结和分析 ,同时还给出了Geo Union的Web应用模式 .最后 ,对WebGIS进一步的工作 ,如互操作问题、安全问题、分布与并发问题以及智能Agent技术等进行了展望     

基于柔性的CAI平台的设计

为了满足教学的需要,在分析了软件系统柔性产生机理的基础上,提出了建立基于柔性CAI平台的思想并给出模型。该模型分为五个层,即:环境支持层、运行平台支持层、物理管理层、映射层和应用层,并具体讨论了每一层的功能和开发方法。该平台提供了三个不同层次的柔性,即:面向开发员级、面向教师级和面向学生级的柔性应用平台。最后,结合物理CAI平台设计实例进行了说明,证明基于柔性的CAI平台适应能力强,使用方便。     

MPLS二、三层VPN实现与分析

采用MPLS技术组建的IP主干网对VPN有着有力的支持,MPLS技术可以在二、三层上实现VPN,但两种方法各有优缺点。文中描述了MPLS隧道技术的主要思想,分析了基于MPLS技术的二、三层VPN工作机制,比较了MPLS二、三层VPN的工作特点,提出了要根据VPN网络设计性能和目标,合理选择基于MPLS技术的VPN方案组建所需要的VPN。