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The summer of 2019 witnessed a great number of wildfires around the globe.For example,wildfires scorched huge swaths of Alaska,British Columbia in Canada,and parts of Greenland.And forest fires in Siberia and the Far East of Russia were also very serious,affecting nearly 3 million hectares of land,and putting some parts of Russia into a state of emergency.In particular,forest fires in the Amazon region had attracted global attention.According to Science,as of August 24,BraziPs National Institute for Space Research had counted more than 41000 fires this year,86%more than last year,compared with 22000 in the same period last year.Scientists in Brazil and elsewhere believe that the recent increase of wildfires is closely related to the increasing ac・tivities of deforestation(Arruda et al.,2019;Escobar,2019). 相似文献
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河口三角洲和沿海城市面临着台风、暴雨、高潮位和上游下泄洪水叠加的“四碰头”复合极端风暴洪水的严重威胁。构建了大气-海洋-陆地相耦合的一体化数值模拟系统,实现了上海市“风”“暴”“潮”“洪”多灾种复合情景的极端洪涝淹没模拟,并验证了耦合方法的有效性,为复合风暴洪水的一体化模拟提供了一套可行的数值模拟方法。在9711台风影响下,模拟了1998年堤防升级改造后淹没面积(水深>0.2m)比改造前减少了62%,表明沿海沿江堤防设施建设在上海市防台防汛中起着关键性的作用。复合极端风暴洪水的有效模拟可为财产保险和未来市政规划提供参考。 相似文献
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GUO Huihui BAO Zhenmin DU Huixia ZHANG Lingling WANG Shi SUN Luyang MOU Xiaoyu HU Xiaoli 《中国海洋大学学报(英文版)》2013,12(1):97-102
Cytochrome P450 (CYP) superfamily is one of the membership largest and function most diverse protein superfamily recogniozed among living beings. Members of this superfamily were further assigned to different families and subfamilies based on their amino acid similarities. According to their phylogenetic relationships, the CYP genes which likely diverged from common ancestor gene and may share common functions were grouped into one clan. Widely distributing scallops are a group of the most conspicuous bivalve; however the studies on their CYP is acarce. In this study, we searched the genome and expressed sequence tags of Zhikong scallop (Chlamys farreri) for CYP genes. In total, 88 non-redundant CYP were identified, which were homed in 13 CYPs gene families. Phylogenetic analysis divided these genes into 4 CYP clans. As in deuterostomes, Clan 2 was the largest, which contained 33 genes belonging to CYP1, CYP2, CYP17 and CYP356 families. Clan 3 contgained 19 genes belonging to CYP3, CYP5 and CYP30 families. Clan 4 contained 23 genes, all belonging to CYP4 family. The mitochondrial CYP clan contained 9 genes belonging to CYP10 and CYP24 families. In comparison, protostomes (C. farreri, D. pluex, D. melanogaster) contained more CYP genes than deuterostomes (S. purpuratus and vertebrates) in Clan 2 but less genes in Clan 3 and Clan 4. Our findings will aid to deciphering CYP function and evolution in scallops and bivalves. 相似文献
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针对平均粒径对砂土剪切特性的影响作用，结合室内试验和离散元模拟方法对不同平均粒径砂土进行了细观研究。基于3种不同平均粒径砂土的直剪试验结果，通过建立反映砂土剪切试验特征的PFC（particle flow code）颗粒流模型，详细研究了不同粒径砂土在剪切过程中土样体积变化、力链网络、孔隙率和配位数等细观结构参数的变化特征和规律，并从细观角度分析了颗粒粒径对土样宏观剪切特性的影响机制。结果表明：具有不同平均粒径砂土的细观结构参数在剪切过程中存在显著差异，并且其细观参数差异主要集中体现在剪切带处；剪切力学特性的影响主要体现在抗剪强度和剪胀效应方面，砂土平均粒径越大，抗剪强度越高，剪胀效应越明显；具有不同平均粒径的砂土在剪切过程中土颗粒运动规律及剪切带形态变化特征存在一定的差异，平均粒径越大，剪切带内上跨式颗粒占比越大，剪切带厚度越大。 相似文献
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从安徽气象为农服务的个性化、精细化、便捷化、智能化需求出发,基于Android和iOS两个移动开发平台,采用无线终端数据采集、用户行为分析、服务信息精准推送等技术,研发了"惠农气象"手机客户端,平台集天气预报、即时消息服务、农情田管、专家互动、农业资讯、滞销帮扶等农业气象服务于一体,为新型农业经营主体、涉农专家、基层气象信息员与农技人员提供分时、分区、分众的气象与农业综合信息服务。该平台已在安徽省市县3级气象与农业部门得到广泛应用,实现了"互联网+气象+农业"智慧服务。 相似文献
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土壤水分传感器在现场安装后,需要针对现场土壤状况对其进行率定,以便校准率定关系。在工程实践中,土壤水分传感器现场率定是一项步骤繁杂、操作要求高、现场取土难度大、耗时较长的一项工作,严重困扰工程项目的实施。开展基于原状土柱率定土壤水分传感器研究,通过现场采集原状土柱,在实验室浸泡至饱和后取出,让土壤水分自然散失,用称重法定期称量原状土柱重量,同时记录土壤水分传感器原始测量值,以此来研究土壤水分传感器的工程率定问题,探讨提高现场安装的土壤水分传感器率定效率的方法,具有现实意义。 相似文献
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含煤岩系中存在着多种矿产和元素,统称为煤的共伴生矿产。然而,煤的共生矿产与伴生矿产明显不同,主要体现在成矿过程、赋存方式及其后期开采形式等方面,至今二者概念较为模糊,需要进一步区分。通过详细分析了煤共生、伴生矿产的特征,根据矿产在煤层中的赋存状态、存在位置及与煤的关系,认为煤的伴生矿产包括煤层气、煤成气、镓、铀、锗、钒等,共生矿产包括页岩气等,而油页岩、粘土与高岭土则既是伴生矿产也是共生矿产。在此基础上,该文提出了煤的共生、伴生矿产分类方案,对煤系矿产资源的勘探与开发有着重要的指导意义。 相似文献
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Sea Level Rise and Its Risk Management 总被引：2，自引：0，他引：2
Sea level rise is among the most severe societal consequences of anthropogenic climate change. Significant advance has been achieved in recent years in the study of future sea level rise and its risk management practice: ①Sea level rise is considered as a kind of hazard,its future plausible scenarios and their probabilities are necessary to be predicted and estimated,and the upper limit with very low probability and high consequences should be emphasized. For this purpose,a complete probability distribution framework has been developed to predict the scenarios and probabilities of future sea level rise with Representative Concentration Pathways (RCPs) and the Shared Socioeconomic Pathways (SSPs) in recent years. ② For a high emissions scenario,it was found that Antarctic Ice Sheet might make a contribution to Global Mean Sea Level (GMSL) rise as high as 78150 cm (mean value 114 cm) by 2100. For the same scenario,the IPCC Fifth Assessment Report gave an Antarctic contribution of only -8+14 cm (mean value 4 cm). ③ Recent studies recommended a revised worst-case (Extreme) GMSL rise scenario of 2.5 m from previous 2.0 m by 2100. It is recognized that GMSL rise will not stop at 2100; rather,it will continue to rise for centuries afterwards,but the degree of uncertainty related to sea level rise will increase. ④ Approaches of combining the upper-bound scenario and a central estimate or mid-range scenario, Adaptation Pathways and robust decision-making are developed to provide a set of long-term planning envelope. These decision-making methods are used widely in coastal risk management related to future sea level rise. Sea level rise and its risk management need to enhance monitoring,analysis and simulation to predict the global,regional and local seal level rise scenarios and the probabilities with different time scales,reduce the estimate uncertainty, assess its upper limits, and enhance decision methods and their application under deep uncertain, in order to meet the needs of climate change adaptation planning,decision-making and long-term risk management in coastal regions. 相似文献
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With the gradual yet unequivocal phasing out of ozone depleting substances(ODSs), the environmental crisis caused by the discovery of an ozone hole over the Antarctic has lessened in severity and a promising recovery of the ozone layer is predicted in this century. However, strong volcanic activity can also cause ozone depletion that might be severe enough to threaten the existence of life on Earth. In this study, a transport model and a coupled chemistry–climate model were used to simulate the impacts of super volcanoes on ozone depletion. The volcanic eruptions in the experiments were the 1991 Mount Pinatubo eruption and a 100 × Pinatubo size eruption. The results show that the percentage of global mean total column ozone depletion in the 2050 RCP8.5 100 × Pinatubo scenario is approximately 6% compared to two years before the eruption and 6.4% in tropics. An identical simulation, 100 × Pinatubo eruption only with natural source ODSs, produces an ozone depletion of 2.5% compared to two years before the eruption, and with 4.4% loss in the tropics. Based on the model results,the reduced ODSs and stratospheric cooling lighten the ozone depletion after super volcanic eruption. 相似文献