排序方式: 共有43条查询结果,搜索用时 31 毫秒
1.
板齿鼠种群数量中长期预测的时间序列模型 总被引:11,自引:1,他引:10
本文利用时间序列方法(三次指数平滑法),并结合季节指数法,建立了板齿鼠种群数量中长期预测(6个月~1年)的时间序列模型,依据1991年11月~1993年12月在广东省博罗县石湾镇里波水管理区对板齿鼠种群数量动态的调查数据,分别预测了1994年和1995年板齿鼠种群数量的发生,预测准确率达到了86.56%。 相似文献
2.
For calculating the total annual Olea pollen concentration, the onset of the main pollen season and the peak pollen concentration dates, using data from 1998 to 2004, predictive models were developed using multiple regression analysis. Four Portuguese regions were studied: Reguengos de Monsaraz, Valença do Douro, Braga and Elvas. The effect of some meteorological parameters such as temperature and precipitation on Olea spatial and temporal airborne pollen distribution was studied. The best correlations were found when only the pre‐peak period was used, with thermal parameters (maximum temperature) showing the highest correlation with airborne pollen distribution. Independent variables, selected by regression analysis for the predictive models, with the greatest influence on the Olea main pollen season features were accumulated number of days with rain and rainfall in the previous autumn, and temperatures (average and minimum) from January through March. The models predict 59 to 99% of the total airborne pollen concentration recorded and the initial and peak concentration dates of the main Olea pollen season. 相似文献
3.
Much of the current interest in pollen time series analysis is motivated by the possibility that pollen series arise from
low-dimensional chaotic systems. If this is the case, short-range prediction using nonlinear modeling is justified and would
produce high-quality forecasts that could be useful in providing pollen alerts to allergy sufferers. To date, contradictory
reports about the characterization of the dynamics of pollen series can be found in the literature. Pollen series have been
alternatively described as featuring and not featuring deterministic chaotic behavior. We showed that the choice of test for
detection of deterministic chaos in pollen series is difficult because pollen series exhibit power spectra. This is a characteristic that is also produced by colored noise series, which mimic deterministic chaos in
most tests. We proposed to apply the Ikeguchi–Aihara test to properly detect the presence of deterministic chaos in pollen
series. We examined the dynamics of cedar (Cryptomeria japonica) hourly pollen series by means of the Ikeguchi–Aihara test and concluded that these pollen series cannot be described as
low-dimensional deterministic chaos. Therefore, the application of low-dimensional chaotic deterministic models to the prediction
of short-range pollen concentration will not result in high-accuracy pollen forecasts even though these models may provide
useful forecasts for certain applications. We believe that our conclusion can be generalized to pollen series from other wind-pollinated
plant species, as wind speed, the forcing parameter of the pollen emission and transport, is best described as a nondeterministic
series that originates in the high dimensionality of the atmosphere. 相似文献
4.
We develop a model to estimate the influence of child and parental characteristics on the likelihood that a child will become an obese or overweight youth. We use this model to test whether it is possible to forecast obesity and overweight among youth. Comparing Receiver Operating Characteristic (ROC) scores from these forecasts, we find that a model using childhood covariates does as well in forecasting youth obesity and overweight as a model using the covariate values contemporaneous with the youth obesity and overweight outcomes. The datasets used in this paper, the National Longitudinal Survey of Youth (NLSY79) and the NLSY79 Children and Young Adults, provide data from 1986 to 2002, allowing for the study of a child's transition to and from obesity or overweight over a long period. Explanatory variables that significantly influence the likelihood of youth obesity or overweight outcomes include the mother's obesity status and education, the youth's mental health, and certain demographic features including race, sex, and family size. These factors provide potential targets for policies that could be implemented early in life among children most likely to become obese or overweight. 相似文献
5.
6.
土壤水分含量的理论分析及预测模型 总被引:5,自引:0,他引:5
本文应用物理学中的电介质和电磁理论,分析和研究土壤的组成成分,得到了反映土壤水分含量的理论表达式,并在自行研制的测试仪器上,对相关变量进行测量,由此建立了土壤水分含量的预测模型,统计检验和国代结果显示了理论模型和预测模型的合理性. 相似文献
7.
应用物元评判识别模型预测农业害虫种群动态 总被引:1,自引:0,他引:1
论述了物元评判识别模型的建模方法,并探讨了该模型在预测农业害虫种群动态方面的应用.结果表明,其历史拟合率高达 92.31%,将 1995年作为独立样本进行试报,其预报结果与实际发生一致.并指出物元评判模型是预测农业害虫种群动态的一种优良模型. 相似文献
8.
农业害虫发生动态的Fuzzy优选识别模式及其应用 总被引:1,自引:1,他引:0
本文对山东省曲阜市1982-1994年二代棉铃虫发生动态的虫情与相应年份的气象资料进行了数量分析,应用Fuzzy优选识别原理,建立了二代棉铃虫发生动态的Fuzzy优选识别模式·对历史资料进行回代验证,其历史拟合率为 100%.书 1995,1996 两年的观测数据资料作为独立样本进行试报,预测结果与实际一致.本研究为农业害虫发生动态的预测预报提供了一种新的研究方法. 相似文献
9.
Idalia Kasprzyk 《International journal of biometeorology》2009,53(4):345-353
Forecasting the time when the atmospheric pollen season of allergenic plants begins is particularly important for doctors
and their patients. The aim of this paper is to determine whether it is possible to forecast the start of the oak (Quercus) pollen season in Rzeszów, Poland. In the elaboration of the most effective model, various forecasting techniques were tested:
growth degree days (GDD°C); meteorological factors; bioclimatic factors; and indicator taxon. The aerobiological monitoring
was carried out in 1997–2005 and 2007 in Rzeszów (SE Poland). In the presented investigation, three methods defining the start
of the Quercus pollen season were selected on the basis of accumulated sums of pollen or the constant occurrence of pollen grains in air.
Despite the application of different combinations of GDD°C methods and threshold temperatures, the correlation coefficients
between the expected and obtained values were low. In some cases, however, they proved highly effective for the test years
(2005, 2007) with the accuracy of a few days. For GDD°C methods, the best threshold temperatures range between 5 and 6°C.
Models based on bioclimatic indices and meteorological variables were not satisfactory. On the basic of the 10 years of results,
the method of indicator species were good for forecast the start of oak pollen season. Birch was the best indicator taxa. 相似文献
10.