高光谱影像概率分类向量机分类方法研究

从分析基于支持向量机和相关向量机的高光谱影像分类方法的优势和不足出发,将基于概率分类向量机的方法用于高光谱影像分类试验。在贝叶斯理论框架下,概率分类向量机为基函数权值引入截断Gauss先验概率分布,使得不同类别的基函数权值具有不同符号的先验分布,并利用EM算法进行参数推断,得到足够稀疏的概率模型,弥补了相关向量机选取错误类别的样本作为相关向量的不足,从而有效地提高了模型的分类精度和稳定性。OMIS和PHI影像分类试验表明,概率分类向量机能够很好地应用在高光谱影像分类。     

甘肃兰州盆地古近系泥岩的古盐度分析

兰州盆地位于青藏高原东北部,祁连山以东,黄土高原以西,古近纪出露地层为细柳沟组、野狐城组和咸水河组下段。作为青藏高原寒区、东部季风区及西北干旱区的交汇地带,兰州地区新生代环境研究受到越来越多的关注,因此有必要对其沉积环境进行研究。本文通过对兰州盆地黄羊头地区古近系进行分段采样,并对泥岩样品的主量元素、微量元素及X射线衍射进行测定,运用硼法、B/Ga值及Sr/Ba值等方法定量—半定量分析兰州盆地古近系沉积时的古盐度特征,同时结合风化指数CIA值的变化特征,综合分析古近系的沉积环境。研究结果表明兰州盆地古近系细柳沟组、野狐城组及咸水河组下段Adams法古盐度值为9.5‰～14.0‰,平均值为11.8‰;Couch法古盐度值为8.2‰～12.8‰,平均值为10.8‰,为内陆半咸水—淡水湖泊。Adams法古盐度值与B/Ga值具有良好的正相关关系,而Adams古盐度值与Sr/Ba值相关性不明显,主要由于地层中生物对Sr的富集作用,导致Sr/Ba值偏大,表明Sr/Ba值不适用于生物富集地层的古盐度恢复。环境研究认为细柳沟期,气候湿润,以冲积扇沉积为主,水体较浅,盐度值较大;到野狐城中期水体加深,变为湖相沉积,气候温暖湿润,盐度值降低,同时存在明显的干冷气候间隙,该间隙期湖盆蒸发量大于补给量,盐度值升高;从野狐城晚期开始湖盆逐渐萎缩,以滨湖相沉积为主,到韩家井期变为河流相沉积,至甘家滩期再次转为湖相沉积,盐度值先升高后降低,但整体风化程度明显降低,表明从野狐城组晚期开始气候逐渐变冷变干。     

近年我国十大重要金属矿种找矿重大进展与成果

近年我国重要矿产资源勘查成果不断快速涌现。为服务矿产勘查进展长期动态跟踪与成果集成研究,2010~2014年,笔者依托原中国地质调查局发展研究中心承担的《重点成矿区带矿产勘查跟踪与成果集成》、《全国地质勘查进展分析》等项目,以铁、铜、铝、铅锌、金、钨、锡、钼、镍、锰等十大重要金属矿产勘查进展为主要研究对象,研究分析了勘查成果特征。     

Interdecadal variations of cold air activities in Northeast China during springtime

Based on the daily mean temperature data of CN05.2 from 1961 to 2012, cold events (CEs) are first divided into two categories according to their duration: strong cold events (SCEs) and weak cold events (WCEs). Then, the characteristics of CEs, SCEs, and WCEs during springtime are investigated. The results indicate that in the pre-1990s epoch, ENSO and Arctic Oscillation events in the previous winter are closely related to SCEs in the following spring. The multidecadal variations of CEs, SCEs, and WCEs are obvious. The intensity trend for SCEs is significantly negative, but it seems less apparent for WCEs. Further analysis reveals that when both SCEs and WCEs occur, a typical East Asian trough in the 850- hPa wind field, whose northwesterly wind component invades Northeast China (NEC) and causes freezing days, can be found in every decade. For the SCEs, a cold vortex, with its center located over Okhotsk and northeasterly current affecting NEC, is found as an additional feature. For the WCEs, the cold vortex is located in Karafuto and its northwesterly airflow intrudes into NEC. As for the difference between SCEs and WCEs, the northwestern flow is weaker while the northeastern counterpart is stronger during the SCEs, in all decades. In the Takaya–Nakamura flux and divergence fields, for the SCEs, a divergence center exists over NEC; and over its downstream regions, a stronger divergence center appears, not like a wave train. However, the opposite is the case for the WCEs; moreover, the wave train appears clearly during the WCEs, which means that the wave energy can propagate and dissipate more easily during WCEs.