Obtaining soil and land quality indicators using research chains and geostatistical methods

Soil and land quality indicators play an important role in the assessment and evaluation of soil and land quality. In contrast with the general definitions of soil and land quality, working with indicators demands a better awareness of at which scale level measurements were made, at which scale calculations and models were developed and validated, and at which scale answers are needed. We propose that soil and land quality indicators may be classified by three characteristics: 1) scale level, 2) complexity, and 3) transferability. Each characteristic is represented by an axis in the Soil and Land Quality Indicator Diagram.Indicators with a high complexity can not be measured directly, but need to be calculated with one or more models, eg. pedotransfer functions and hydrological simulation models. For the application of the indicator it is then important to know how the indicator value was obtained, i.e. which models were used. A specific sequence of models used for obtaining an indicator value is called a research chain and is indicated in the Scale Hierarchy and Knowledge Type Diagram. The use of research chains allows the user to consider and evaluate alternative options for the assessment of a specific indicator.In this study values for three soil quality indicators were obtained through two alternative research chains. The research chains differed by the choice of used pedotransfer functions and soil hydrological models. The two research chains yielded for each of the three indicators two sets of thirty year averages for 166 locations in the study area. Per location the obtained indicator values were compared with a t-test. The research chains were found to yield significantly different values for all three indicators.The spatial and temporal variability of the data was analyzed for each step, i.e. per model, along both research chains. Alternative models yielded different spatial and temporal variability structures. Therefore, the choice of research chain not only affects the mean value of an indicator, but also the associated spatial and temporal variability structure. Knowledge of the spatial and temporal variability is important for upscaling purposes.Based on these results we conclude that the successful application of soil and land quality indicators depends on:1) the definition of suitable indicators based on scale level, complexity, and transferability; 2) the careful selection and definition of research chains; and 3) the combined presentation of indicator values and used research chains.     

低频交变场磁模型实验方法

以低频交变磁场模拟地磁场,用可塑性高阻磁性材料作成磁性体模型,观测交变磁场激发下磁模型体产生的交变二次磁场。     

鄂东矽卡岩型铜矿床的地球化学异常模式

总结了鄂东矽卡岩型铜矿的地球化学特征,建立了相应的地球化学异常模式,提出了寻找矽卡岩型铜矿的指示元素及地球化学找矿标志。     

太阳能热水监测系统的数据处理及分析

针对系统的工艺流程、监测数据、经济指标进行了分析;阐述了系统的总体研究方案及设计思路;重点研究了经济指标数学模型的建立和数据处理的方法.该系统实现了对太阳能保证率、太阳能集热系统效率、太阳能热水系统效率、太阳能集热系统有用得热量、常规能源替代量5个经济指标按周的计算.基于.NET平台测试结果表明,本设计的监测系统数据处理方法能对所提供的监测数据进行处理和分析,为可再生能源示范建筑的示范性提供了有效、可靠的依据.     

挣值管理在信息系统开发项目中的实施分析

该文探讨了挣值管理在软件开发项目实施中的应用,以某公司信息系统开发项目为例,对挣值分析在项目管理中的应用实施进行了分析。     

Short term forecasting with support vector machines and application to stock price prediction

Forecasting a stock price movement is one of the most difficult problems in finance. The reason is that financial time series are complex, non stationary. Furthermore, it is also very difficult to predict this movement with parametric models. Instead of parametric models, we propose two techniques, which are data driven and non parametric. Based on the idea that excess returns would be possible with publicly available information, we developed two models in order to forecast the short term price movements by using technical indicators. Our assumption is that the future value of a stock price depends on the financial indicators although there is no parametric model to explain this relationship. This relationship comes from the technical analysis. Comparison shows that support vector regression (SVR) out performs the multi layer perceptron (MLP) networks for a short term prediction in terms of the mean square error. If the risk premium is used as a comparison criterion, then the SVR technique is as good as the MLP method or better.     

网络教育精品课程评审指标变化的启示

本文在简单分析精品课程内涵及其建设意义的基础上,回顾了07年网络教育精品课程评审情况,全面介绍07年到08年网络精品课程评审指标的具体变化,并由此变化分析网络精品课程评审的方向,展望网络精品课程未来的发展方向。     

Local and global error estimations in linear structural dynamics

The study discusses the concept of error estimation in linear elastodynamics. Two different types of error estimators are presented. First ‘classical’ methods based on post-processing techniques are discussed starting from a semidiscrete formulation. The temporal error due to the finite difference discretization is measured independently of the spatial error of the finite element discretization. The temporal error estimators are applied within one time step and the spatial error estimators at a time point. The error is measured in the global energy norm. The temporal evolution of the error cannot be reflected. Furthermore the estimators can only evaluate the mean error of the whole spatial domain. As the second scheme local error estimators are presented. These estimators are designed to evaluate the error of local variables in a certain region by applying duality techniques. Local estimators are known from linear elastostatics and have later on been extended to nonlinear problems. The corresponding dual problem represents the influence of the local variable on the initial problem and may be related to the reciprocal theorem of Betti–Maxwell. In the present study this concept is transferred to linear structural dynamics. Because the dual problem is established over the total space–time domain, the spatial and temporal error of all time steps can be accumulated within one procedure. In this study the space–time finite element method is introduced as a single field formulation.     

小城镇可持续发展评价指标体系研究

小城镇可持续发展涉及自然资源、生态环境、社会经济活动等众多领域,是一个非常复杂的统.本文在全面总结国内外城市可持续发展指标体系研究现状的基础上,从中国的国情出发,将从经济、社会生活、资源环境三个方面来构建小城镇可持续发展评价指标体系.文章末以重庆某郊县作为试验研究区,以该县2000～2002年相关数据,建立了可持续发展评价指标体系,旨在对该指标体系进行定量评判.     

水利水电工程勘测中物勘方法与技术应用

目前我国在水利水电勘测方面方法多种多样。随着高科技的发展和运用,我国的勘测水平也得到了大幅度的提高。但是,我国的地质复杂多变,水文状况多种多样,并且各种因素都处在不断地变化之中,为了提高水利水电的勘测效率,得到更加准确的、科学的勘测结果,还应发展更高水平的水利水电的勘测方法,从而加快我国的水利水电工程的发展。