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农业害虫数量达到防治标准以上,对农业就会造成危害,没有适时的予测和防治,就可能产生严重的后果。害虫数量何时达到防治标准以上,要靠对害虫发生量及其它项目的予测。目前害虫发生量予测方法虽有七、八种,但定量予测方法不够多。发生量予测水平低于其它项目。因此对预测方法应进一步探讨。本文以数学模型观点做一点尝试。一、种群的数学模型设二元函数P(x,t)表示在t时刻年令在[x,x+△x]中,个体数为P(x,t)△x,P(x,t)称为害虫按年令分布的密度,
When the number of agricultural pests reaches above the prevention and control standard, it will cause harm to agriculture. Without proper forecasting and prevention and control, serious consequences may occur. When the number of pests reaches the standard of prevention and control, it depends on the amount of pests and other items to be estimated. Although there are seven or eight kinds of methods for predicting the occurrence of pests, there are not many methods for quantitative determination. The level of occurrence is lower than other items. Therefore, the prediction method should be further explored. This article makes a few attempts from the viewpoint of mathematical model. First, the mathematical model of the population Let the binary function P (x, t) denote the number of individuals P (x, t) Δx, P (x, t) Known as the density of pests distributed by year,