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641.
综合利用前人研究结果与江苏地区水稻生长所需的光、温、水特性,提出了江苏水稻气候适宜性评价指标为适宜生长期、5—10月降水量、t≥10℃活动积温、日照时数;依据现有稻麦(油)两熟的耕作制度,确立了江苏水稻气候适宜性区划因子和分级阈值。基于1961—2019年江苏省及周边共85个站(市、区)的气象数据,采用模糊综合评判法建立水稻气候适宜性评估模型,并确定综合评估指数,利用ArcGIS的自然断点法,将江苏中熟中粳、迟熟中粳、早熟晚粳、中熟晚粳种植适宜区进行区划。通过30a尺度下的年代际分析发现,由于适宜生长期延长和活动积温增加,使得四个品种特性的水稻适宜种植区域均有所调整,其中晚熟粳稻的种植范围北扩到淮河以南地区。 相似文献
642.
2014年5月27日湖北房县发生了一次M4.0地震,房县三海村井水位有明显前兆异常。该井是湖北省唯一一个存在水温负梯度现象的静水位井。虽然前人对井水温的动态变化进行过大量的研究,但主要是对水温、水位的对比研究和水化学分析,将水温与地质构造相结合的研究相对较少。结合INSAR影像图、水化学资料、水文地质资料和地质构造资料探讨该井水温负梯度产生的原因以及该井的水温、水位是否受周围地质构造的影响。研究成果对地下流体与周围构造的相关性研究有一定的参考意义。 相似文献
643.
不同类型铀矿床的沥青铀矿/晶质铀矿具有不同的稀土元素组成,其组成可作为判别铀矿床类型的重要指标。采用基于Python语言的主成分分析(principal component analysis,PCA)与支持向量机(support vector machines,SVM)结合的分类模型,对收集到的全球已知6种类型铀矿床的216组沥青铀矿/晶质铀矿稀土元素数据进行研究。以216组数据为训练集,通过数据清洗、特征缩放、PCA特征提取、网格搜索和交叉验证参数寻优构建SVM分类模型,对24组同变质型胡家峪晶质铀矿进行智能识别。研究结果显示:仅使用稀土元素的14维训练集最优模型判定胡家峪晶质铀矿类型的测试准确率为0.4%;由稀土元素、稀土总量、轻重稀土比、铕异常组成的17维训练集最优模型的测试准确率为75.0%,较14维训练集提高74.6%,模型泛化能力强;而通过传统稀土元素配分曲线、w(ΣREE)-(LREE/HREE)N图解不能有效判定胡家峪晶质铀矿类型。本次研究表明,PCA-SVM算法对增有传统稀土判别指标数据集进行挖掘可有效厘定铀氧化物成因类型,效果明显优于单纯的稀土元素数据集以及传统的稀土配分曲线、w(ΣREE)-(LREE/HREE)N图解。 相似文献
644.
首先分析对比了国产小型IMU/GPS组合导航获取的小POS数据特点,因仪器精度有限引起的测量误差无法在成像过程中消除,相位误差导致了Mini SAR影像中部分目标成像出现方位向散焦、模糊,导致目标像点坐标出现误差。将传统定向参数计算方法用于Mini SAR单幅影像定位时,地面控制点数量、像点坐标、定向参数误差向量的限差、地形特征、DEM分辨率及POS数据精度等因素都会影响定位结果。当对定位精度要求不高时,多项式插值POS数据获取的天线相位中心的空间位置、速度比拟合更准确。 相似文献
645.
646.
Jin Xu Peng Liu Haixia Wang Jingjing Lian Bo Li 《Journal of the Indian Society of Remote Sensing》2018,46(12):1949-1961
Marine radar oil spill monitoring technology has the advantages of wide-range target detection, a flexible working mode, and the ability to operate in severe weather. Based on oil spill data collected from the 7.16 accident in Dalian, China, two comprehensive oil spill monitoring methods using X-band horizontal polarized marine radar are presented. The improved Prewitt operator, Otsu algorithm, median filtering, and mean filtering were used to preprocess the original marine radar image. Subsequently, the recognition of offshore oil films were studied via the dual-threshold method and C–V level set method. Results show that the image data achieved the ideal noise reduction effect after pretreatment, and retained marine radar ocean wave information effectively. The C–V level set method required relatively lower levels of data preprocessing. However, it relied heavily on the energy-driven window by expert presupposition. It was therefore only suitable for obtaining continuous oil film information. Its calculation efficiency was related to the number of evolutions and the size of the image. The dual-threshold method required higher data preprocessing. Furthermore, the effective monitoring range of ocean waves must be determined in advance. This method could identify discrete oil film information at sea and had high computational efficiency. The dual-threshold method is better for the automatic identification of marine oil film information. The two kinds of monitoring methods described herein are useful for the identification and disposal of oil spills at sea. 相似文献
647.
Climate change is one of the most active research fields currently, which has attracted extensive attention from the international community. In order to better understand the development situation and research status of international climate change science, in this paper we took the SSCI and SCI databases as data sources, collected the relevant literatures since 1900 based on the key words related to climate change, and made some statistics and analysis of the literatures of the past one hundred years to reveal the development process of climate change research as well as the development and evolution of its research topics and hot spots. The results showed that the climate change research began in the late 18 th century and early 19 th century, and the academic debate about global warming and global cooling started in the early 1970s. The international programs and projects led by a range of international organizations and intergovernmental bodies have contributed significantly to the rapid development of climate change research. The United States and the United Kingdom have long been the core countries of climate change research. The proportion of Chinese papers has risen rapidly in the last decade. The intensity and scope of scientific research cooperation are constantly expanding. Current research focuses on climate model/modeling, climate simulation, climate policy, climate sensitivity, climate change impacts, climate change adaptation, climate change mitigation, and rate of climate change. 相似文献
648.
德兴斑岩铜矿田黄铁矿Re-Os同位素定年及其地质意义 总被引:1,自引:1,他引:0
德兴斑岩铜矿田是中国东部最大的斑岩铜矿系统,一直以来,德兴铜矿的成矿过程和成因机制都是矿床学家关注的热点问题。前人在德兴铜矿的围岩蚀变、矿化期次、流体特征、成岩年代等方面取得了较为一致的认识,但其成矿时代仍争议较大。文章首次对矿田内与黄铜矿密切共生的黄铁矿进行了Re-Os同位素定年,10件样品中的4件w(Re)极低,模式年龄变化范围大,且误差较大,故不对其进行讨论;其余6件的w(Re)为10.58×10~(-9)~102.59×10~(-9),普通w(Os)较低(0.0054×10~(-9)~0.0113×10~(-9)),w(~(187)Os)较高(0.019×10~(-9)~0.177×10~(-9)),Re/Os比值较高(4406~73 422),为低含量高放射性Os成因硫化物。研究获得黄铁矿Re-Os同位素加权平均模式年龄为(165.3±2.3)Ma(MSWD=1.04)。因此,德兴铜矿的铜成矿年龄为中侏罗世,综合前人资料,德兴铜矿最可能形成于古太平洋板块俯冲的远程效应影响下的陆内伸展的地质背景,为陆内环境斑岩铜矿。 相似文献
649.
W. Shi H. Li G. Liao G. Pei Y. Lin 《International Journal of Environmental Science and Technology》2018,15(11):2337-2348
Arsenic in groundwater is a serious environmental problem. The contamination of groundwater with arsenic has been of utmost concern worldwide. Steel slag is a solid waste generated from steel production. Although steel slags have been used for arsenic removal from water, this process has not been systematically or integratively researched. In this study, the arsenic removal capacity and mechanism were investigated for carbon steel slag, stainless steel slag and Fe-modified stainless steel slag based on an in-depth study. The study also evaluated the potential utilization of different steel slag for regeneration. The maximum adsorption of arsenic on carbon steel slag, stainless steel slag and Fe-modified stainless steel slag was 12.20, 3.17 and 12.82 mg g?1 at 25 °C, respectively. The modification of stainless steel slag by FeC13 can generate more pore structures and larger surface areas, and 300 °C treatment produces the best regeneration efficiency. The ΔG values were negative for all of the steel slags, indicating the spontaneous nature of the adsorption process. The solution pH was a critical parameter for the removal of arsenic for steel slags. Under highly alkaline solution conditions, the mechanism of arsenic removal by carbon steel slag and stainless steel slag can be attributed to chemisorption, including chemical precipitation and coordination reactions, and under weakly alkaline solution conditions, electrostatic interaction and specific adsorption are the arsenic removal mechanisms by Fe-modified stainless steel slag. Regeneration of the Fe-modified stainless steel slag was better achieved than that of the other steel slags in the application of high-temperature treatment. 相似文献
650.
基于自然灾害风险理论,利用海南省18个站点气象资料、瓜菜生产和社会经济要素资料,通过灾情反演,构建苗期湿涝、冬季寒害和春季干旱致灾等级指标。综合致灾、孕灾、灾损、防灾能力,进行瓜菜气象灾害的综合风险分析与区划。结果表明:苗期湿涝危险性从西南至东北增加,春季干旱危险性东西高、中间低;西瓜寒害危险性从中部向两边减小,豇豆和丝瓜寒害危险性从南往北加重,辣椒寒害危险性从东南到西北增加;苗期湿涝孕灾环境敏感性从中部山区向沿海和平原地区增加,春季干旱和冬季寒害趋势相反;瓜菜灾损风险和防灾能力在区域上存在明显差异;西瓜、豇豆和辣椒气象灾害综合风险总体趋势一致,高风险区集中在海南东部地区;丝瓜气象灾害综合风险高值区在北部地区。 相似文献