基于GOES数据和弱约束变分的地表水热通量估算     

刘翔舸  黄健熙  秦军  王鹏新  徐同仁 《农业机械学报》2014,45(1):236-245

基于弱约束的四维变分方法和陆面过程模式发展了一个地表温度的陆面数据同化系统。本文反演了地球静止业务环境卫星(Geostationary operational environmental satellite,GOES)的地表温度,并将反演的地表温度同化入陆面过程模式,改进陆面过程模式中地表水热通量的估算精度。以弱约束的变分方法通过在代价函数中增加弱约束项代替陆面过程模式动力方程组中存在的模式误差,构建新的代价函数并对其优化,从而改善模式中显热与潜热的估算精度。将GOES地表温度与实测地表温度进行比较,其均方根误差(RMSE)作为试验中的观测误差。选择美国通量网AmeriFlux中2个主要农业站点的气象和通量数据作为试验数据,对同化系统进行驱动和验证。结果表明同化后的地表温度、潜/显热估算精度均有提高。其中,各站地表温度RMSE平均仅为1 K,显热通量平均RMSE下降22 W/m2,潜热通量平均RMSE下降26 W/m2。因此结合陆面过程模式的弱约束变分方法同化GOES反演温度产品估算近地表水热通量的方法是有效且可行的。  相似文献   

DBSCAN算法优化及在村镇管理决策中的应用     

彭波  史春雷  高万林 《农业机械学报》2016,47(10):346-350

作为空间数据挖掘技术中的一种,带有噪声的空间聚类应用算法(DBSCAN算法)是基于密度的聚类算法,其可以从空间数据库中发现任意形状的聚类。本文研究了基于密度的空间聚类算法优化原理及实现过程,分析了原始DBSCAN算法存在的问题,通过避免公共领域对象的重复查询,减少对核心对象邻域查询的计算,优化后算法的时间效率提高了33.73%。将优化后的DBSCAN算法应用于村镇网格化管理,可对网格化管理系统中的数据记录进行有效挖掘,为村镇管理工作提供信息和辅助决策。  相似文献   

农业物料力学试验测控系统设计   总被引：6，自引：2，他引：6  

王剑平  盖玲  王俊 《农业机械学报》2002,33(1):51-53

介绍了基于计算机的农业物料力学试验测控系统的组成和测控软件。应用结果表明，该系统工作可靠，虚拟仪器面板操作简便，实现了农业物为力学试验数据采集及试验过程自动化。  相似文献   

计算机辅助设计线图数据处理的灰色模型与方法   总被引：5，自引：3，他引：5  

何哲明  罗佑新  张龙庭  郭惠昕 《农业机械学报》2002,33(1):94-96,105

在分析计算机辅助设计线图数据处理的现状后，提出了其线图数据处理的灰色模型参数估计的函数变换法。实例表明，该方法简单实用，值得在计算机辅助设计中推广使用。  相似文献   

植物修复对锰尾渣污染土壤特性的影响     

向言词 冯涛刘炳荣  许中坚曾荣今  严明理杨柳 《土壤侵蚀与水土保持学报》2007,21(6):79-82

采用盆栽法研究栽培美洲商陆和大豆进行植物修复后,锰尾渣污染土壤特性的变化。栽培美洲商陆和大豆可增加土壤的碱解氮、速效磷、速效钾和有机质。栽培植物后,土壤pH值变化不显著,但土壤磷酸酶、尿酶、蛋白酶、蔗糖酶、硝酸还原酶和脱氢酶的活性都高于对照。栽培植物可影响土壤锰和镉的形态分布,降低土壤锰和镉总含量,减少土壤水溶性锰和镉含量。在锰尾渣污染区域,混种美洲商陆与大豆进行植物修复,改良土壤特性更佳。  相似文献   

Novel Alkaloids from Marine Actinobacteria: Discovery and Characterization     

Anne-Sofie De Rop  Jeltien Rombaut  Thomas Willems  Marilyn De Graeve  Lynn Vanhaecke  Paco Hulpiau  Sofie L. De Maeseneire  Maarten L. De Mol  Wim K. Soetaert 《Marine drugs》2022,20(1)

The marine environment is an excellent resource for natural products with therapeutic potential. Its microbial inhabitants, often associated with other marine organisms, are specialized in the synthesis of bioactive secondary metabolites. Similar to their terrestrial counterparts, marine Actinobacteria are a prevalent source of these natural products. Here, we discuss 77 newly discovered alkaloids produced by such marine Actinobacteria between 2017 and mid-2021, as well as the strategies employed in their elucidation. While 12 different classes of alkaloids were unraveled, indoles, diketopiperazines, glutarimides, indolizidines, and pyrroles were most dominant. Discoveries were mainly based on experimental approaches where microbial extracts were analyzed in relation to novel compounds. Although such experimental procedures have proven useful in the past, the methodologies need adaptations to limit the chance of compound rediscovery. On the other hand, genome mining provides a different angle for natural product discovery. While the technology is still relatively young compared to experimental screening, significant improvement has been made in recent years. Together with synthetic biology tools, both genome mining and extract screening provide excellent opportunities for continued drug discovery from marine Actinobacteria.  相似文献   

Metal contamination from open-cast copper and sulphur mining in southeast Ireland     

C. Herr  C. O'Neill  N. F. Gray 《Land Degradation \u0026amp; Development》1996,7(2):161-174

The metal content was determined in soil and vegetation around the eastern zone of the disused sulphur and copper mines at Avoca (southeast Ireland). A 250 m × 250 m grid survey was conducted covering a total area of 4 km². The mining belt was in the centre of the investigated site and was sampled separately. Iron, Zn, Cu and Cd concentrations in soil and plant material were determined, in addition to soil organic matter content and soil pH. Soil samples taken from the spoil showed elevated Cu and Cd concentrations, and low soil pH and organic matter content. At least 50 per cent of the agricultural sites examined around the East Avoca Mine showed elevated soil Cu and Cd concentrations, whereas Zn and Fe soil concentrations were within the range for unpolluted soils. None of the vegetation analysed had elevated Zn, Cd, Fe or Cu concentrations. Overall there was no indication of serious metal contamination in either soils or vegetation surrounding the mine in spite of extensive dust deposition during open-pit mining activity 15–30 years ago. However, a plume of elevated Cu in the soil was identified, which originated from a large spoil heap and had been spread for some 2·0 km by the prevailing wind.  相似文献   

Long-term consequences of topsoil mining on select biological and physical characteristics of two New Zealand loessial soils under grazed pasture     

P. B. S. Hart  J. A. August  A. W. West 《Land Degradation \u0026amp; Development》1989,1(2):77-88

Soil chemical, biochemical, biological and structural properties were measured in two New Zealand loessial soils that were topsoil-mined 10 and 25 years ago respectively. Measurements at the 10-year site were compared to some earlier measurements made at this site and the data combined in a chronological sequence for analysis. Topsoil mining had a large, detrimental impact on the soil microbial biomass, the earthworm populations, easily mineralizable N and soil enzyme activities. However, most of these properties substantially recovered, to 80-90 per cent of the levels in unmined soils, within 10-25 years of restoration under pasture. In contrast, while total soil C and N were less affected by topsoil mining, their recovery was much slower. Stabilities of macro-aggregates of soil had fully recovered within 10-25 years after topsoil mining. The apparent changes in all the measured properties between 10 and 25 years of restoration were small in comparison with changes between 0-10 years of restoration after topsoil mining. The total C content of both soils under pasture appeared unlikely to attain the levels present in unmined soils. In soils undergoing restoration, the ratio of microbial C/total soil C may be a useful index of soil ‘biological stability’. Sulphatase activity may reflect the recovery of pasture production.  相似文献   

杨庄煤矿区农田塌陷水域多介质OCPs污染特征及生态风险研究     

周晓芳  高良敏  陈晓晴  查甫更  王新富 《农业环境科学学报》2020,39(5):1085-1093

为研究采煤活动影响下农田塌陷水域有机氯农药(OCPs)的污染特征及潜在生态风险,使用GC-MS对淮南潘一矿的杨庄农田塌陷区水体和底泥中的OCPs特征污染物六六六(HCHs)及滴滴涕(DDTs)进行质量浓度测定,利用ArcGIS进行OCPs分布特征及来源研究,并选择共识沉积物质量基准法(CB-SQGs)对潜在生态风险进行分析。结果表明:杨庄沉陷区溶解态ΣOCPs质量浓度范围为72.06～218.89 ng·L~(-1),均值为167.32 ng·L~(-1);悬浮态和沉积态ΣOCPs范围为199.35～405.04 ng·g~(-1)dw和24.34～1 247.32ng·g~(-1)dw,均值为277.07 ng·g~(-1)dw和238.78 ng·g~(-1)dw;悬浮态和沉积态OCPs质量浓度自上游向下游方向随水流呈削减趋势;杨庄塌陷水体中HCHs主要来自于林丹,DDTs主要来自于农业三氯杀螨醇;溶解态OCPs低于国家Ⅲ类水质标准限额,处于低生态风险水平;悬浮态和沉积态OCPs处于中高生态风险水平,其中沉积态OCPs毒性发生率略低于悬浮态OCPs毒性发生率。  相似文献   

南方某矿区土壤镉污染及作物健康风险研究   总被引：2，自引：0，他引：2  

张妍  张磊  程红光  孙海旭  崔祥芬 《农业环境科学学报》2020,39(12):2752-2761

为了评估南方某县土壤镉污染情况、量化当地不同作物镉含量并对不同人群健康风险进行评估,从该县3个镇采集135份土壤样本,入户采集128份自产大米样本,种植区采集7份脐橙样本,对其中镉含量进行测定。结果表明,3镇采集土壤样品镉超标率分别为41.67%、28.81%和21.62%,地累积指数计算得到该县68.9%的土壤样本受到不同程度的镉污染,大米镉含量超标率分别为48.57%、34.48%、8.82%。而脐橙果肉样品中镉含量较低,远低于0.05 mg·kg^-1。计算不同作物的危害商数（HQ）可得,食用自产大米的危害商数（HQ）值普遍大于1,风险较高,而食用脐橙果肉产生的健康风险低。种植脐橙具有一定的经济效益,且当地具有脐橙适宜的生长条件,故考虑在重污染区种植脐橙取代种植水稻。  相似文献