地震发生时间对人员伤亡影响的概率

本文用泊松分布表示家庭人数的概率分布,并假定在闲暇时间段人在室内的概率服从均匀分布,根据人在一天中的活动建立了不同时间段人在室内的概率公式。用一天中不同时间段人在室内的概率表示地震发生时间对人员伤亡的影响。     

Lake management techniques in Florida,USA: Costs and water quality effects

Economic evaluations of restored or enhanced lakes in Florida indicated gravity drawdown was the least expensive action, whereas effluent diversion was 10,000 times more costly on a per hectare basis, with the other lake treatment costs occurring in the following order: gravity drawdown < grass carp introduction < mechanical drawdown < aeration < stormwater control = drawdown-dredging < effluent diversion. Within a particular treatment category, the costs spanned approximately one and one half orders of magnitude. Contrary to the abundant cost data, which permitted an economic analysis, inappropriate statistical design and lack of commitment toward sampling Florida's restored lakes undermines attempts to understand long-term water quality responses to various enhancement techniques. Using Lake Tohopekaliga as a case study, ordinary statistical tests produced contradictory and unreliable interpretations on the effectiveness of drawdown and phosphorus removal at sewage treatment plants in improving the trophic state index. This emphasizes the need for more robust statistical approaches and more detailed data collection in evaluating lake restoration activities It is unfortunate for Florida's lake restoration program that quantitative conclusions based on inferential statistics, replete with tests of assumptions, is limited to very few lakes     

UNIT HYDROGRAPHS FOR DEVELOPING DESIGN FLOOD HYDROGRAPHS1

ABSTRACT: In Illinois, a procedure has been developed to derive unit hydrographs for generating 100-year and probable maximum flood hydrographs, on the basis of 11 parameters that define the hydrograph shape very well. Regional regressions of these parameters with basin factors show very high correlation. Thus satisfactory values of parameters can be determined for ungaged areas or those with a few years' record. The nonlinearity in unit hydrographs derived from usual floods is largely attributed to mixing within-channel and overbank-flow flood events. To minimize the effects of nonlinearity and to derive unit hydrographa suitable for calculating spillway design floods, use of the proposed method of developing such hydrographs is recommended.     

PERIODIC AUTOREGRESSIVE-MOVING AVERAGE (PARMA) MODELING WITH APPLICATIONS TO WATER RESOURCES1

Results involving correlation properties and parameter estimation for autoregressive-moving average models with periodic parameters are presented. A multivariate representation of the PARMA model is used to derive parameter space restrictions and difference equations for the periodic autocorrelations. Close approximation to the likelihood function for Gaussian PARMA processes results in efficient maximum-likelihood estimation procedures. Terms in the Fourier expansion of the parameters are sequentially included, and a selection criterion is given for determining the optimal number of harmonics to be included. Application of the techniques is demonstrated through analysis of a monthly streamflow time series.     

SOME SIMPLE MODELS FOR DISCRETE VARIATE TIME SERIES1

ABSTRACT: Simple models are presented for use in the modeling and generation of sequences of dependent discrete random variables. The models are essentially Markov Chains, but are structurally autoregressions, and so depend on only a few parameters. The marginal distribution is an intrinsic component in the specification of each model, and the Poisson, Geometric, Negative Binomial and Binomial distributions are considered. Details are also given for the introduction of time-dependence into the means of the sequences so that seaonality can be treated simply.     

APPROACHES TO MULTIVARIATE MODELING OF WATER RESOURCES TIME SERIES1

ABSTRACT: Alternative approaches suggested for modeling multiseries of water resources systems are reviewed and compared. Most approaches fall within the general framework of multivariate ARMA models. Formal modeling procedures suggest a three-stage iterative process, namely: model identification, parameter estimation and diagnostic checks. Although a number of statistical tools are already available to follow such modeling process, in general, it is not an easy task, especially if high order vector ARMA models are used. However, simpler ARMA models such as the contemporaneous and the transfer-function models may be sufficient for most applications in water resources. Two examples of modeling bivariate and trivariate streamflow series are included. Alternative modeling procedures are used and compared by using data generation techniques. The results obtained suggest that low order models, as well as contemporaneous ARMA models, reproduce quite well the main statistical characteristics of the time series analyzed. It is assumed that the same conclusions apply for most water resources time series.     

西南地区的大气灾害及其时空变化规律

本地区为季风型、山地型和中纬多灾型的混合型多灾区，有七类３２种大气灾害、五类２８种大气灾链。在本区，受灾的面积和人口、死人、经济损失和灾种之最，皆推大气灾害，尤以旱灾类最重，其次是暴雨类。从主导的灾害类型、类、种的角度，将本地区划分成２大区、９区、１２亚区和５小区。近５００年来，大旱、大涝平均每２２．２年发生一次。     

非线性时序法在城市大气污染预测中的应用

建立城市大气污染预测模型是治理城市大气污染的重要工作。在简述时间序列方法基本原理的基础上，分析了系数为变量的自回归滑动平均（ARMA）模型、截断ARMA模型，和残差为自回归综合滑动平均（ARIMA）的半参数方法等城市大气污染预测模型。以法国某城市为例，分别采用AR模型和系数为变量的AR模型对大气污染进行了预测。通过比较预测结果可知，基于非线性时间序列方法的城市大气污染预测模型可以提高预测精度，降低预测误差。     

我国能源消费与环境质量变化的关联分析

本文对我国1990-2004年能源消费与环境质量的变化态势以及二者之间关系的实证分析结果表明：我国能源消费与整体环境质量变化和局部环境质量有着高度的相关性；环境质量的改善不能仅依靠环境保护来实现，还应考虑能源消费的发展变化和影响。     

河南省洪涝灾害时间序列的分形特征与R/S分析

基于河南省1000~1999年的洪涝灾害统计资料,运用分形理论对河南省洪涝灾害的时间序列特征进行分析,发现河南省洪涝灾害发生时间序列的分步呈现出明显的分形特征,其分形维数为0.517,同严格意义上的数学分形Cantor集合相比分维数较小,说明河南省洪涝灾害发生发展的自组织程度还有进一步发展的趋势,其危害程度将可能进一步提高;在河南省洪涝灾害发生时间序列的分形特征的基础上,通过R/S分析,得出该省洪涝灾害发生时间序列的H指数为0.580,说明河南省洪涝灾害具有长期相关性,且未来的洪涝灾害发生的次数具有不断增加的趋势。