In this article, a model of a weed control threshold forecast system has been established, with related model solving, data checking, database setting up, and system engineering illustration. Moreover, it is tested by...In this article, a model of a weed control threshold forecast system has been established, with related model solving, data checking, database setting up, and system engineering illustration. Moreover, it is tested by a software with data from a sugar cane planting experimental field in Yunnan, China. The methodology behind the detailed system analysis, design, and engineering has been discussed. The issue of how to create a dynamic data-dependent forecast model of a threshold forecast system, whose threshold changes according to the change of planting environment has been solved. Hence an effective solution has been initiated for further development on an agricultural expert system.展开更多
This paper proposes useful guidance on the choice of threshold for binary forecasts. In weather forecast systems, the probabilistic forecast cannot be used directly when estimated too smoothly. In this case, the binar...This paper proposes useful guidance on the choice of threshold for binary forecasts. In weather forecast systems, the probabilistic forecast cannot be used directly when estimated too smoothly. In this case, the binary forecast, whether a meteorological event will occur or not, is preferable to the probabilistic forecast. A threshold is needed to generate a binary forecast, and the guidance in this paper encompasses the use of skill scores for the choice of threshold according to the forecast pattern. The forecast pattern consists of distribution modes of estimated probabilities, occurrence rates of observations, and variation modes. This study is performed via Monte-Carlo simulation, with 48 forecast patterns considered. Estimated probabilities are generated by random variate sampling from five distributions separately. Varying the threshold from 0 to 1, binary forecasts are generated by threshold. For the assessment of binary forecast models, a 2×2 contingency table is used and four skill scores （Heidke skill score, hit rate, true skill statistic, and threat score） are compared for each forecast pattern. As a result, guidance on the choice of skill score to find the optimal threshold is proposed.展开更多
本文描述了疣纹蝙蝠蛾的生物学特性,通过对水曲柳解析木分析,研究了该虫的危害对水曲柳材积、树高和胸径的影响,以此确定了防治值。经统计,该虫幼虫为6龄,各虫期的 T 与 V 之间的一元回归方程为:卵期 T=7.65+126.47V;幼虫越冬前期 T=13....本文描述了疣纹蝙蝠蛾的生物学特性,通过对水曲柳解析木分析,研究了该虫的危害对水曲柳材积、树高和胸径的影响,以此确定了防治值。经统计,该虫幼虫为6龄,各虫期的 T 与 V 之间的一元回归方程为:卵期 T=7.65+126.47V;幼虫越冬前期 T=13.77+641.51V;幼虫越冬后期 T=17.38+84.95V;蛹期 T=17.57+91.53V。展开更多
文摘In this article, a model of a weed control threshold forecast system has been established, with related model solving, data checking, database setting up, and system engineering illustration. Moreover, it is tested by a software with data from a sugar cane planting experimental field in Yunnan, China. The methodology behind the detailed system analysis, design, and engineering has been discussed. The issue of how to create a dynamic data-dependent forecast model of a threshold forecast system, whose threshold changes according to the change of planting environment has been solved. Hence an effective solution has been initiated for further development on an agricultural expert system.
文摘This paper proposes useful guidance on the choice of threshold for binary forecasts. In weather forecast systems, the probabilistic forecast cannot be used directly when estimated too smoothly. In this case, the binary forecast, whether a meteorological event will occur or not, is preferable to the probabilistic forecast. A threshold is needed to generate a binary forecast, and the guidance in this paper encompasses the use of skill scores for the choice of threshold according to the forecast pattern. The forecast pattern consists of distribution modes of estimated probabilities, occurrence rates of observations, and variation modes. This study is performed via Monte-Carlo simulation, with 48 forecast patterns considered. Estimated probabilities are generated by random variate sampling from five distributions separately. Varying the threshold from 0 to 1, binary forecasts are generated by threshold. For the assessment of binary forecast models, a 2×2 contingency table is used and four skill scores （Heidke skill score, hit rate, true skill statistic, and threat score） are compared for each forecast pattern. As a result, guidance on the choice of skill score to find the optimal threshold is proposed.
文摘本文描述了疣纹蝙蝠蛾的生物学特性,通过对水曲柳解析木分析,研究了该虫的危害对水曲柳材积、树高和胸径的影响,以此确定了防治值。经统计,该虫幼虫为6龄,各虫期的 T 与 V 之间的一元回归方程为:卵期 T=7.65+126.47V;幼虫越冬前期 T=13.77+641.51V;幼虫越冬后期 T=17.38+84.95V;蛹期 T=17.57+91.53V。
