飞机噪声对机场周围社区的污染是航空环境工程领域的重要问题,限制飞机最大起飞重量(MTOW)或合理规划机场周围社区已成为降低飞机噪声对机场社区噪声污染的2种主要途径。为了实现这2种途径从定性分析向定量研究的转化,对飞机噪声等值线...飞机噪声对机场周围社区的污染是航空环境工程领域的重要问题,限制飞机最大起飞重量(MTOW)或合理规划机场周围社区已成为降低飞机噪声对机场社区噪声污染的2种主要途径。为了实现这2种途径从定性分析向定量研究的转化,对飞机噪声等值线面积与测量点上声暴露级(SEL)之间的准确关系进行了研究。以飞机离场为例,建立了等值线面积与测量点上声暴露级之间关系数学分析模型,利用INM计算的42种机型等值线面积和声暴露级数据,进行了所建模型的合理性和等值线面积与声暴露级之间线性相关性的有效性的验证,得到声暴露级减低1 d B对给定值等值线面积减小的程度或等值线面积按比例减小对噪声级减低的大小。从而为机场周围社区飞机噪声污染定量化控制开辟了新的方法。展开更多
On farm bio-resource recycling has been given greater emphasis with the introduction of conservation agriculture specifically withclimate change scenarios in the mid-hills of the north-west Himalaya region（NWHR）. Un...On farm bio-resource recycling has been given greater emphasis with the introduction of conservation agriculture specifically withclimate change scenarios in the mid-hills of the north-west Himalaya region（NWHR）. Under this changing scenario, elevation, slope aspect and integrated nutrient management（INM） may affect significantly soil quality and crop productivity. A study was conducted during 2009-2010 to 2010-2011 at the Ashti watershed of NWHR in a rainfed condition to examine the influence of elevation, slope aspect and integrated nutrient management（INM） on soil resource and crop productivity. Two years of farm demonstration trials indicated that crop productivity and soil quality is significantly affected by elevation, slope aspect and INM. Results showed that wheat equivalent yield（WEY） of improved technology increased crop productivity by -20%-37% compared to the conventional system. Intercropping of maize with cowpea and soybean enhanced yield by another 8%-17%. North aspect and higher elevation increased crop productivity by 15%-25% compared to south aspect and low elevation（except paddy）. Intercropping of maize with cowpea and soybean enhanced yield by another 8%-15%. Irrespective of slope, elevation and cropping system, the WEY increased by -30% in this region due to INMtechnology. The influence of elevation, slope aspect and INM significantly affected soil resources（SQI） and soil carbon change（SCC）. SCC is significantly correlated with SQI for conventional（R2 = 0.65＊）, INM technology（R2 = 0.81＊） and for both technologies（R2 = 0.73＊）. It is recommended that at higher elevation.（except for paddy soils） with a north facing slope, INM is recommended for higher crop productivity; conservation of soil resources is recommended for the mid hills of NWHR; and single values of SCC are appropriate as a SQI for this region.展开更多
文摘飞机噪声对机场周围社区的污染是航空环境工程领域的重要问题,限制飞机最大起飞重量(MTOW)或合理规划机场周围社区已成为降低飞机噪声对机场社区噪声污染的2种主要途径。为了实现这2种途径从定性分析向定量研究的转化,对飞机噪声等值线面积与测量点上声暴露级(SEL)之间的准确关系进行了研究。以飞机离场为例,建立了等值线面积与测量点上声暴露级之间关系数学分析模型,利用INM计算的42种机型等值线面积和声暴露级数据,进行了所建模型的合理性和等值线面积与声暴露级之间线性相关性的有效性的验证,得到声暴露级减低1 d B对给定值等值线面积减小的程度或等值线面积按比例减小对噪声级减低的大小。从而为机场周围社区飞机噪声污染定量化控制开辟了新的方法。
文摘在分布式集群系统中,数据根据划分算法存储在集群的各个节点,这为涉及大量连接操作的复杂查询带来了昂贵的网络开销。针对该问题,基于信息网模型INM(Information Network Mode),提出最小通信量查询划分算法和多目标查询优化算法。其中查询划分算法将复杂查询划分成多个PWOC(parallelizable without communication)子查询,所有子查询可近似无通信地并行执行。多目标优化算法将子查询作为查询计划的基本操作,并将并行性和通信代价同时作为驱动目标,以传统多目标加权算法结合贪心策略作为评估依据生成查询计划树。最后,系统基于TPC-H基准生成测试数据,将原始算法与优化算法进行了对比实验,结果表明优化算法可以极大提高复杂查询的效率。
文摘On farm bio-resource recycling has been given greater emphasis with the introduction of conservation agriculture specifically withclimate change scenarios in the mid-hills of the north-west Himalaya region（NWHR）. Under this changing scenario, elevation, slope aspect and integrated nutrient management（INM） may affect significantly soil quality and crop productivity. A study was conducted during 2009-2010 to 2010-2011 at the Ashti watershed of NWHR in a rainfed condition to examine the influence of elevation, slope aspect and integrated nutrient management（INM） on soil resource and crop productivity. Two years of farm demonstration trials indicated that crop productivity and soil quality is significantly affected by elevation, slope aspect and INM. Results showed that wheat equivalent yield（WEY） of improved technology increased crop productivity by -20%-37% compared to the conventional system. Intercropping of maize with cowpea and soybean enhanced yield by another 8%-17%. North aspect and higher elevation increased crop productivity by 15%-25% compared to south aspect and low elevation（except paddy）. Intercropping of maize with cowpea and soybean enhanced yield by another 8%-15%. Irrespective of slope, elevation and cropping system, the WEY increased by -30% in this region due to INMtechnology. The influence of elevation, slope aspect and INM significantly affected soil resources（SQI） and soil carbon change（SCC）. SCC is significantly correlated with SQI for conventional（R2 = 0.65＊）, INM technology（R2 = 0.81＊） and for both technologies（R2 = 0.73＊）. It is recommended that at higher elevation.（except for paddy soils） with a north facing slope, INM is recommended for higher crop productivity; conservation of soil resources is recommended for the mid hills of NWHR; and single values of SCC are appropriate as a SQI for this region.
