Climate change has become a global phenomenon and is adversely affecting agricultural development across the globe.Developing countries like Pakistan where 18.9%of the GDP(gross domestic product)came from the agricult...Climate change has become a global phenomenon and is adversely affecting agricultural development across the globe.Developing countries like Pakistan where 18.9%of the GDP(gross domestic product)came from the agriculture sector and also 42%of the labor force involved in agriculture.They are directly and indirectly affected by climate change due to an increase in the frequency and intensity of climatic extreme events such as floods,droughts and extreme weather events.In this paper,we have focused on the impact of climate change on farm households and their adaptation strategies to cope up the climatic extremes.For this purpose,we have selected farm households by using multistage stratified random sampling from four districts of the Potohar region i.e.Attock,Rawalpindi,Jhelum and Chakwal.These districts were selected by dividing the Potohar region into rain-fed areas.We have employed logistic regression to assess the determinants of adaptation to climate change and its impact.We have also calculated the marginal effect of each independent variable of the logistic regression to measure the immediate rate of change in the model.In order to check the significance of our suggested model,we have used hypothesis testing.展开更多
针对装备寿命试验中失效样本量比较小的情形,基于应力冲击思想,提出了一种基于失效选择机制的装备系统可靠性评估定量分析方法。首先引入图示评审技术(Graphic evaluation and review technique,GERT)表征系统的多种工作状态和状态间的...针对装备寿命试验中失效样本量比较小的情形,基于应力冲击思想,提出了一种基于失效选择机制的装备系统可靠性评估定量分析方法。首先引入图示评审技术(Graphic evaluation and review technique,GERT)表征系统的多种工作状态和状态间的传递关系,根据系统结构进行可靠性评估建模。然后基于失效观测数据对元器件的可靠性进行估计,确定可靠性评估GERT网络中的参数。最后依据失效选择机制对网络进行计算,实现系统可靠性的评估。算例研究结果表明了基于失效选择机制的装备可靠性评估GERT模型的有效性。展开更多
文摘Climate change has become a global phenomenon and is adversely affecting agricultural development across the globe.Developing countries like Pakistan where 18.9%of the GDP(gross domestic product)came from the agriculture sector and also 42%of the labor force involved in agriculture.They are directly and indirectly affected by climate change due to an increase in the frequency and intensity of climatic extreme events such as floods,droughts and extreme weather events.In this paper,we have focused on the impact of climate change on farm households and their adaptation strategies to cope up the climatic extremes.For this purpose,we have selected farm households by using multistage stratified random sampling from four districts of the Potohar region i.e.Attock,Rawalpindi,Jhelum and Chakwal.These districts were selected by dividing the Potohar region into rain-fed areas.We have employed logistic regression to assess the determinants of adaptation to climate change and its impact.We have also calculated the marginal effect of each independent variable of the logistic regression to measure the immediate rate of change in the model.In order to check the significance of our suggested model,we have used hypothesis testing.
文摘针对装备寿命试验中失效样本量比较小的情形,基于应力冲击思想,提出了一种基于失效选择机制的装备系统可靠性评估定量分析方法。首先引入图示评审技术(Graphic evaluation and review technique,GERT)表征系统的多种工作状态和状态间的传递关系,根据系统结构进行可靠性评估建模。然后基于失效观测数据对元器件的可靠性进行估计,确定可靠性评估GERT网络中的参数。最后依据失效选择机制对网络进行计算,实现系统可靠性的评估。算例研究结果表明了基于失效选择机制的装备可靠性评估GERT模型的有效性。
