3种垃圾填埋气预测模型的比较研究

文章分析了3种典型的生活垃圾填埋气预测模型:德国模型、IPCC推荐模型、动力学模型(Marticorena模型)的机理;以重庆市长生桥垃圾填埋场为例,探讨了3种模型的参数确定,据此预测了相应填埋堆体的长期产气情况,比较讨论了各模型预测结果的差异,并对其适用性进行了分析。结果表明,3种模型反映的填埋气体变化的趋势是一致的,3个模型所产生填埋场气的峰值大小顺序为:IPCC推荐模型(4.2×107m3/a)>Marticorena动力学模型(4.1×107m3/a)>德国模型(3.6×107m3/a)。根据现场实测数据的验证,在封场之前采用德国模型进行测算比较合适;封场之后采用IPCC或Marticorena动力学模型则更加符合实际情况。

沈阳市老虎冲垃圾填埋场填埋气产量估算

通过选取3种不同的填埋气预测模型:IPCC模型、中国填埋气估算模型、德国模型,结合沈阳市老虎冲填埋场的实际情况,对各参数进行了修订,从而预测老虎冲填埋场填埋气产量情况,并分析比较各模型预测结果。结果表明,2003—2011年,3种模型反映了相同的填埋气变化趋势,趋于上升状态;2012—2025年,由于填埋量发生变化,IPCC模型与中国填埋气估算模型和德国模型的填埋气变化情况相反,呈下降趋势。3种模型预测的填埋气产量的峰值大小为:中国填埋气估算模型为3.3×107m3/a,IPCC模型为2.1×107m3/a,德国模型为9.8×106m3/a。根据实际产气情况进行对比,发现德国模型更符合实际情况。

Return threshold model analysis of two stock markets： Evidence study of Italy and Germany＇s stock returns

This paper discusses the model construction and the association between the Italy and the Germany＇s stock markets. The period of study data is from January 3, 2000 to June 30, 2008. This paper also utilizes Student＇s t distribution to analyze the proposed model. The empirical results show that the two stock markets are mutually affected each other, and the dynamic conditional correlation （DCC） and the bivariate asymmetric-GARCH （1, 2） model is appropriate in evaluating the relation between them. The empirical result also indicates that Italy and Germany＇s stock markets show a positive relationship. The average value of correlation coefficient equals to 0.8424, which implies that the two stock markets return volatility have a synchronized influence on each other. In addition, the empirical result also shows that there is an asymmetrical effect between Italy and the Germany＇s stock markets, and demonstrates that the good news and bad news of the stock returns＇ volatility will produce the different variation risks for Italy and the Germany＇s stock price markets.