Mechanism of frost heave by film water migration under temperature gradient

Conclusions Based on the principle of freezing point superposition, a model for predicting unfrozen water content is worked out and it can consider the influences of five factors: soil variation, water content, temperature, solution concentration and overburden pressure. The difference of values between determination and calculation is less than 3 %. According to the curve of unfrozen water content vs. temperature and initial freezing point and temperature at the cold end of soil body, a way for estimating ice segregation temperature is presented. The difference of values between determination and calculation is less than 0.3°C. The thickness of frozen fringe changing with time has three models. The calculation method needs further study.     

Circulation in the western tropical Pacific Ocean and its seasonal variation

An assimilation data set based on the GFDL MOM3 model and the NODC XBT data set is used to examine the circulation in the western tropical Pacific and its seasonal variations. The assimilated and observed velocities and transports of the mean circulation agree well. Transports of the North Equatorial Current (NEC), Mindanao Current (MC), North Equatorial Countercurrent (NECC) west of 140°E and Kuroshio origin estimated with the assimilation data display the seasonal cycles, roughly strong in boreal spring and weak in autumn, with a little phase difference.The NECC transport also has a semi-annual fluctuation resuiting from the phase lag between seasonal cycles of two tropical gyres' recirculations. Strong in summer during the southeast monsoon period, the seasonal cycle of the Indonesian throughfiow (ITF) is somewhat different from those of its upstreams, the MC and New Guinea Coastal Current (NGCC), implying the monsoon's impact on it.     

A new method for preparation of template DNA for PCR from special plant materials

A simple method for preparation of template DNA suitable for PCR amplification from herbarium sampies and plant tissues rich in byproducts, e.g. polysaccharides, tannins, polyphenolic, and terpenoids compounds, is described. The total DNA from regular extraction procedure is absorbed by a small amount of glass powder and the final precipitation of glass powder is used directly as a template for PCR. Taking six plant taxa, including the herbarium specimens of Lythraceae collected from Namibia in 1957 and the silicon-dried leaf tissue from mangrove plants (Rhizophoraceae and Combretaceae) rich in by-products as exampies, the PCR products, including nrDNA ITS regions and cpDNA rbcL gene, amplified following the regular and new methods respectively are compared. Our method provides a simple, rapid and economic approach to purify and prepare template DNA for PCR from special plant materials.``     

CO2 background concentration in the atmosphere over the Chinese mainland

Based on the long-term monitoring data on CO₂ concentration, variation trend and characteristics of CO₂ background concentration in the atmosphere over the Chinese mainland are analyzed. Results show that the increasing trend of CO₂ background concentration in the atmosphere over the Chinese mainland has appeared during the period of 1991–2000. The average annual CO₂ growth increment is 1.59 μL/L, and the average annual CO₂ growth rate is 0.44%. Distinct seasonal variations of CO₂ background concentration are observed, and the averaged amplitude of CO₂ seasonal variations is 10.35 μL/L. Regional variation characteristics of CO₂ background concentration in the atmosphere and possible impact of human activities on these variations over the Chinese mainland are discussed as well.     

时序分析在研究条干不匀率中的应用

条干不匀率是决定棉纱等级的一个重要指标。在整个纺纱过程——梳棉、并条(头并、二并)、粗纱和细纱中都需要测定它、控制它。我们应用时间序列分析方法,研究了纺纱各工序中条干不匀率的变化规律和各工序间条干不匀率之间的联系,建立了合理的模型和一步预报公式,并对各工序作出了由“今天”预测“明天”的一步预报和在同一天内作出上一工序预测下一工序的一步预报,取得了良好的效果。同时,我们在条干不匀率的建模过程中,在动态数据处理的方法上,推广了“纯季节性乘积模型”,它可分析处理的季节性序列更为广泛,也更切合实际问题的需要。这种推广方法可用于一般的季节性乘积模型。     

A non‐Gaussian generalization of the Airline model for robust seasonal adjustment

In their seminal book Time Series Analysis: Forecasting and Control, Box and Jenkins (1976) introduce the Airline model, which is still routinely used for the modelling of economic seasonal time series. The Airline model is for a differenced time series (in levels and seasons) and constitutes a linear moving average of lagged Gaussian disturbances which depends on two coefficients and a fixed variance. In this paper a novel approach to seasonal adjustment is developed that is based on the Airline model and that accounts for outliers and breaks in time series. For this purpose we consider the canonical representation of the Airline model. It takes the model as a sum of trend, seasonal and irregular (unobserved) components which are uniquely identified as a result of the canonical decomposition. The resulting unobserved components time series model is extended by components that allow for outliers and breaks. When all components depend on Gaussian disturbances, the model can be cast in state space form and the Kalman filter can compute the exact log‐likelihood function. Related filtering and smoothing algorithms can be used to compute minimum mean squared error estimates of the unobserved components. However, the outlier and break components typically rely on heavy‐tailed densities such as the t or the mixture of normals. For this class of non‐Gaussian models, Monte Carlo simulation techniques will be used for estimation, signal extraction and seasonal adjustment. This robust approach to seasonal adjustment allows outliers to be accounted for, while keeping the underlying structures that are currently used to aid reporting of economic time series data. Copyright © 2006 John Wiley & Sons, Ltd.     

空调能效比和季节能效比的分析

针对空调节电问题，通过统计数据和测试数据分析了我国空调产品能效比的基泰情况以及我国国家标；隹中规定能效比值与国外相关标准的差距，指出了我国能效水平提升具有很高的潜力、根据季节温度分布，分析了房间空调器的季节能效比以及冷水机组的综合部分负荷值，得出能效比和房间空调器的季节能效比以及冷水机组的综合部分负荷值对空调节能有同等重要的作用，季节能效比和综合部分负荷值的应用对节电有利．     

水稻纹枯病流行的时间动态模拟分析

通过田间小区试验获得水稻生长季节中纹枯病(Rhizoctonia solani)相对严重度(x)随时间(t)而变化的动态消长曲线,用Epitimulator软件计算出单分子、逻辑斯蒂、龚伯茨和理查德拟合模型.根据各模型的检验参数分析比较4种理论函数对纹枯病进展曲线的拟合性,发现单分子函数的拟合性最差,龚伯茨函数优于逻辑斯蒂函数;当确定适当形状参数m值时,用理查德函数可获得纹枯病发展动态的最优拟合模型,其决定系数最高而卡方值和均方根误差值最小.在实验中设置了3个纹枯病接种处理并获得3条病害进展曲线,用理查德对它们进行拟合所得到的拟合模型分别是:x=[1 0.187 4 exp(-0.213 9 t)]~(-20.5699)±0.0170(m=1.048 6,R=0.982 2,X~2=0.010 9) x=[1-0.690 3 exp(-0.210 3 t)]~(3.6881)±0.0198(m=0.728 9,R=0.988 5,x~2=0.010 9) x=[1 0.636 4 exp(-0.431 6 t)]~(-8.0703)±0.0277(m=1.443 3,R=0.988 2,x~2=0.015 6)     

浅析地方民族广播电视视听资源的收集与利用

本文探讨了民族地区广播电视视听资源的收集途径和方法 ,着重分析了如何在网络环境下进行广播电视视听资源的开发利用。并重点提出了收集具有地方民族特色的广播电视视听资源 ,以满足用户对民族地区视听资源的利用 ,促进民族地区地方文献信息资源的建设和发展     

基于季节ARIMA模型的电力负荷建模与预报

电力负荷是影响电网寿命和可靠度的一个重要因素，将季节ARIMA模型引入电力负荷的建模及预报，为电力资源分配的宏观调控及电网改造提供了一种可靠的方法和途径，文中用频谱分析的方法检验电力负荷的季节性并求出一个周期；介绍了具有一个周期的季节ARIMA模型的一般表达方式，并给出进行建模及预报的一般过程，以天津市华苑小区的电力负荷为例，进行了季节ARIMA模型的建模及预报。