多源高分辨率卫星影像监测黑臭水体的适用性研究

高分辨率卫星的幅宽一般很小,受云雨和轨道回访周期影响,单颗卫星的短时段内覆盖能力有限,因此,单一高分辨率卫星常常无法满足一定时段内的黑臭水体监测需求,需要多源卫星协同监测黑臭水体。为了分析多源高分辨率影像对黑臭水体遥感监测的适用性,本文基于地物光谱仪实测的水体遥感反射率数据,以GeoEye-1、WorldView-2、北京二号(DMC3)、高景一号SV1(SuperView-1)以及GF-PMS系列(GF-1/1B/1C/1D、GF-2、GF-6)传感器波段进行等效计算,结果表明:(1)采用反射率比值模型——BOI(Black and Odorous water Index)模型,GeoEye-1、WorldView-2、SuperView-1和GF-1/1B/1C/1D/2/6影像识别黑臭水体正确率均较高,分别为89.5%、89.5%、92.1%和92.1%。(2)BOI模型不适用于DMC3,这里采用了归一化水体指数NDWI≤0.55判别黑臭水体,识别正确率为89.5%。(3)BOI模型应用于仅有的2景同步卫星影像——GF-2影像,经实测数据验证,识别精度为83.3%,精度较高。针对通州区内的某重叠区,2016年—2021年10颗多源卫星影像协同观测的结果一致性较好,表明了多源遥感影像监测黑臭水体的适用性较好。综合考虑卫星影像空间分辨率和采购成本,给出了合理的协同观测建议。     

北太平洋黑潮延伸体区域和副热带逆流区域中尺度涡能量特征研究

不同科研工作者对黑潮延伸体区域和北太平洋副热带逆流区域的中尺度现象进行过不同的研究,但对两区域中尺度涡进行统一比较分析的工作较少。因此,本文利用11年的卫星高度计海表面高度异常资料分别对这两个区域的中尺度现象特征及其能量变化过程进行系统的分析和对比。研究发现,两区域的气旋涡与反气旋涡在分布、振幅、能量和寿命上均存在差异;进一步的动能谱分析和能量串级讨论发现:两区域的动能谱密度虽均集中在2×10–3～4×10–3 周/km的波数域上,但黑潮延伸体区域大部分涡旋信号分布在经向上,而北太平洋副热带逆流区域主要分布在纬向上,这可能与两区域中尺度涡能量来源的不同有关。由于两区域在2×10–3～3×10–3 周/km的波数域上动能转移项以负值为主,这说明两区域在此波数域上均存在能量源,并且发生能量逆向串级。     

基于多源遥感的中国沿海地区填海造地特征研究

填海造地是沿海地区最为重要的海域使用活动,全面准确掌握沿海地区填海造地活动特征对于海域空间资源综合管理具有重要意义。本文从填海造地海域使用过程出发,将填海造地活动划分为在填区、成陆区、建设区,并采用遥感和GIS技术,判别提取2008-2015年期间沿海地区填海造地影像,并结合海岸地貌特征和开发利用类型对其空间分异特征进行综合分析。结果表明:2008-2015年期间累计填海造地201 738.56 hm2,填海在填区、填海成陆区、填海建设区面积分别为44 607.00 hm2、100 949.65 hm2、56 181.91 hm2;总体空间分布上填海造地在部分地区呈集聚分布态势,与海岸地貌类型紧密关联,低潮出露潮滩海岸填海造地有109 614.38 hm2,河口海湾区域填海造地可达132 767.41 hm2;港口+工业、城镇+旅游两种组合类型是沿海地区典型的填海造地区域开发利用类型。     

换能器声反射系统方向特性的研究

利用圆形平面活塞的方向性特性理论设计声反射罩,研究了换能器声反射系统方向特性。实验表明,理论计算与测量值一致。     

湖南苗儿山韧性剪切带与金矿化

湖南雪峰弧形构造带中的苗儿山韧性剪切带存在糜棱岩和片理化岩石两大构造岩类,各具不同的变形特征,根据金矿的产出规律,认为该地区金矿化受韧性剪切带,老地层,后期脆性断裂等多重因素控制,发育于老地层中的片理化带提供了成矿流体的运移通道和容矿空间,加强片理化带的研究对于在雪峰弧形构造带上找金具有重要意义。     

Seismic data compression by an adaptive local cosine/sine transform and its effects on migration

The local cosine/sine basis is a localized version of the cosine/sine basis with a window function which can have arbitrary smoothness. It has orthogonality and good time and frequency localization properties. The adaptive local cosine/sine basis is a best‐basis obtained from an overabundant library of cosine/sine packets based on a cost‐functional. We propose a 2D semi‐adaptive (time‐adaptive or space‐adaptive) local cosine transform (referred to as a 2D semi‐ALCT) and apply it to the SEG–EAEG salt model synthetic data set for compression. From the numerical results, we see that most of the important features of the data set can be well preserved even in the high compression ratio (CR=40:1) case. Using reconstructed data from the highly compressed ALCT coefficients (CR=40:1) for migration, we can still obtain a high‐quality image including subsalt structures. Furthermore, we find that the window partition, generated by the 2D semi‐ALCT, is well adapted to the characteristics of the seismic data set, and the compression capability of the 2D semi‐ALCT is greater than that of the 2D uniform local cosine transform (2D ULCT). We find also that a (32, 32) or (32, 64) minimum (time, space) window size can generate the best compression results for the SEG–EAEG salt data set.     

The Application of Geotomography in Engineering

It seems that electromagnetic tomography is quite suitable to be used in metal and groundwaterexploration. especial for limestone areas where the absorption coefficient of electromagnetic wave is smalland geological body has a large property contrast with country rock it should be pointed out that there exitsome uncertainties in geological interpretation of EM tomogram, corresponding laboratory tests for rockphysical property are always necessary.Resistivity tomography provides us a new useful…     

四川省投资环境的区域差异

从行政及区位条件、经济基础、基础设施、科研实力、社会服务、资源禀赋、环境状况、市场容量 8大要素 4 8个方面对四川省 2 1个地级区域的投资环境进行综合评价 ,阐述该区域投资环境的区域差异规律及存在的问题和对策。     

First-principle study on phase Al0.8Ni3Sn0.2 in Sn-Ni-Al alloy as anode for lithium ion battery

The mechanism of lithium intercalation/deintercalation for phase Al_0.8Ni₃Sn_0.2 as anode material used in lithium ion battery was studied carefully based on the first-principle plane wave pseudo-potential method. The calculated results indicated that Sn--Ni--Al alloy had high theoretical capacity when used as anode material, however, there was high initial irreversible capacity loss because of the large volume expansion. Therefore the technological parameters during preparing the Sn-Ni-Al anode should be controlled strictly to make the content of Al_0.8Ni₃Sn_0.2 phase as low as possible and to make the anode consist of promising Sn--Ni and Al--Ni phases. For comparison, an experiment based on magnetron sputtering was done. The result showed that the calculation is in good agreement with the experiment. We found that the first-principle investigation method is of far-reaching significance in synthesising new commercial anode materials with high capacity and good cycle performance.     

The Flattening Index of the Eclipse White-Light Corona and Magnetic Fields

From observations of the solar white-light corona at 65 eclipses from 1851 to 2015 we confirm earlier findings that the flattening index of the white-light corona depends on the phase, rather than the magnitude of solar cycles, which is in contrast with behavior of other major solar activity indices like the sunspot number, the 2800 MHz radio flux, etc. This indicates that mechanisms responsible for creation and distribution of helmet streamers, the most essential coronal structures influencing the flattening index, could be of different magnetic nature from those of other manifestations of solar surface activity.