Pollution and Desorption Kinetics of Heavy Metals at Agricultural Soils in Southeastern Iran

Desorption of heavy metals is an important factor in determining heavy-metal availability in soils. The objective of this research was to determine the applicability of kinetic equations to describe the kinetics of copper (Cu) and cadmium (Cd) desorption at two agricultural soils of Kerman Province in Iran. For Cd and Cu desorption studies, 5 g of the air-dried <2-mm soil fraction was extracted with 25 ml of 0.01 M ethylenediamenetetraacetic acid (EDTA) at pH 7.0 with a shaker for periods of 5 to 2880 min. The desorption patterns of Cu and Cd were generally characterized by an initial fast reaction, followed by a slower continuing reaction. Desorption of Cu and Cd from the two soils was equally well described by the two-constant rate and simple Elovich equations. The results of this study can be used to make better prediction about the mobility and bioavailability of the Cu and Cd in soil.     

Cumulative permanent environmental effects for repeated records animal models

The assumption of a single permanent environmental (PE) effect contributing to every record made by an animal is questioned. An alternative model where new PE effects accumulate with each record made by an animal is proposed. An example is used to illustrate the differences between the traditional model and the proposed model.     

关于一类渐近线性椭圆方程

通过一个变形的山路引理及极小作用原理,得到了一类带有Dirichlet边值的渐近线性椭圆方程的解的存在性及多解性.     

非线性植被-侵蚀动力学模型初探

植被-侵蚀动力学是一门研究流域植被与侵蚀在人类活动影响下演变规律的边缘学科.现有植被-侵蚀动力学模型是基于指数增长模型建立的,在多数时段具有较高精度,但在高植被覆盖度（V）、低侵蚀率（E）,以及低V高E等特殊时段精度略差.为提高模型模拟精度并扩大其适用范围,该文提出了一种基于Logistic模型的非线性模型,并将两种模型应用于北京西山地区、宁夏西吉黄家二岔、陕西长武王东沟以及广东惠州上杨试验站等小流域植被及侵蚀演变过程的模拟.结果表明,非线性模型在一般时段的模拟精度与线性模型相当,而在特殊时段,前者的精度明显高于后者.但是非线性模型求解复杂,引入的两个新参数需深入研究确定.同时,由非线性模型推出的植被-侵蚀状态图形式复杂且不完全符合实际情况,不如由线性模型得到的植被-侵蚀状态图简单实用.非线性模型还有待于进一步地修正和完善.      

2005年亳州秋季长连阴雨天气主要成因及其预报

利用NCAR/NCEP再分析资料分析安徽亳州地区2005年9月14～10月7日秋季长连阴雨天气过程期间的500 hPa和地面环流特征,结果表明:西风带低槽活动频繁、副高位置适中稳定使得冷、暖气流持续交汇于黄淮地区是造成秋季连阴雨天气的主要原因.     

中小范围内粮食产量灰色模型预测

利用灰色系统理论的预测和决策功能,对粮食产量进行统计和预测。结果表明：用GM（1,1）模型对粮食产量预测,建模简单,预测精度高,在预测粮食产量、气候变化、农田灾害等方面有较大的实用意义。     

中国苹果产量预测模型比较分析

提出了一种灰色神经网络模型。该模型结合了灰色GM(1,1)预测模型和BP神经网络2种预测模型的优点,并用此模型对我国的苹果产量进行预测。将GM(1,1)预测模型的预测值作为BP神经网络的输入变量,实际值作为输出变量进行神经网络训练。灰色神经网络模型对2004、2005年苹果产量的预测精度分别为98.11%、98.45%,高于单一的灰色GM(1.1)预测模型或BP神经网络。     

Mathematical and statistical modeling of morphometric and planar parameters of barchans in Pashoeyeh Erg in the west of Lut Desert,Iran

Barchan dunes are among the most common accumulative phenomena made by wind erosion, which are usually formed in regions where the prevailing wind direction is almost constant throughout the year and there is not enough sand to completely cover the land surface. Barchans are among the most common windy landscapes in Pashoueyeh Erg in the west of Lut Desert, Iran. This study aims to elaborate on morphological properties of barchans in this region using mathematical and statistical models. The results of these methods are very important in investigating barchan shapes and identifying their behavior. Barchan shapes were mathematically modeled by simulating them in the coordinate system through nonlinear parabolic equations, so that two separate equations were calculated for barchan windward and slip-face parabolas. The type and intensity of relationships between barchan morphology and mathematical parameters were determined by the statistical modeling. The results indicated that the existing relationships followed the power correlation with the maximum coefficient of determination and minimum error of estimate. Combining the above two methods is a powerful basis for stimulating barchans in virtual and laboratory environments. The most important result of this study is to convert the mathematical and statistical models of barchan morphology to each other. Focal length is one of the most important parameters of barchan parabolas, suggesting different states of barchans in comparison with each other. As the barchan's focal length decreases, its opening becomes narrower, and the divergence of the barchan's horns reduces. Barchans with longer focal length have greater width, dimensions, and volume. In general, identifying and estimating the morphometric and planar parameters of barchans is effective in how they move, how much they move, and how they behave in the environment. These cases play an important role in the management of desert areas.     

晚稻稻纵卷叶螟发生气象条件分析与预测方法研究

通过对湖州2001-2012年共12a水稻稻纵卷叶螟发生资料与气象资料进行对比分析,选择影响湖州稻纵卷叶螟发生的气象因子气温、降水、风速、湿度、日照等,考虑前期气象条件和虫源数,通过统计分析方法,建立了水稻纵卷叶螟的发生气象条件等级预报模型。用本地气象台发布的未来10d天气预报结论,结合前期天气实况和当前虫源数,对未来10d稻纵卷叶螟的发生气象条件等级进行预报。预报模型紧密联系预报产品特点和预报服务实际,实用性较强。     

大豆灰斑病流行强度预测模型研究

大豆灰斑病是一个多循环病害,叶、荚病情田间流行曲线均呈"S"型,(Y)1=C/1 ea-bX公式进行曲线方程拟合,拟合方程均达到显著水平.根据荚病指(x)与病粒率(y)的相关建立了荚病指与病粒率的直线回归方程,感病品种Y=3.2 0.8890X,抗病品种Y=1.223 0.7669X.根据病粒率与气象因子的相关关系建立了早熟品种和中晚熟品种灰斑病粒率预测多元回归方程,早熟品种(Y)1(%)=-0.38-0.3889X1 0.7726X2 0.7070X3,中晚熟品种(Y)2(%)=-7.08-6.37×10-2X1 1.405X2 2.694X3.预测方程在一个农场运行结果,预测病粒率与实际调查的病粒率十分接近.