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近半个世纪来气候变暖背景下黄河流域潜在蒸散量的变化(英文)

According to the meteorological observation data of 72 stations from 1960 to 2010 in the Huanghe (Yellow) River Watershed, China, the long-term variations of potential evapotranspiration, calculated in the modified Penman-Monteith model of Food and Agriculture Organization of the United Nations, were presented, as well as the meteorological causes for the decrease of potential evapotranspiration were discussed. Since 1960, temperature has risen significantly and potential evapotranspiration a decreasing trend, which indicated the existence of "Evaporation paradox" in the Huanghe River Watershed. This phenomenon was not consistent spatially or temporally with the increase of temperature, potential evapotranspiration decreased in spring, summer and winter, mainly over most parts of Shanxi and Henan, and some parts of Gansu, Ningxia, Inner Mongolia, and Shaanxi. During the recent half century, the trends of temperature and potential evapotranspiration were negatively correlated at most of the stations, while precipitation and potential evapotranspiration exhibited a contrary trend. Calculated in multiple regressions, the contribution to potential evapotranspiration change of related meteorological factors was discussed, including mean pressure, maximum and minimum temperature, sunshine hours, relative humidity and average wind speed. The decrease of wind speed in the Huanghe River Watershed may be the dominating factor causing potential evapotranspiration decreasing.     

Lithologic mapping of HED terrains on Vesta using Dawn Framing Camera color data

The surface composition of Vesta, the most massive intact basaltic object in the asteroid belt, is interesting because it provides us with an insight into magmatic differentiation of planetesimals that eventually coalesced to form the terrestrial planets. The distribution of lithologic and compositional units on the surface of Vesta provides important constraints on its petrologic evolution, impact history, and its relationship with vestoids and howardite‐eucrite‐diogenite (HED) meteorites. Using color parameters (band tilt and band curvature) originally developed for analyzing lunar data, we have identified and mapped HED terrains on Vesta in Dawn Framing Camera (FC) color data. The average color spectrum of Vesta is identical to that of howardite regions, suggesting an extensive mixing of surface regolith due to impact gardening over the course of solar system history. Our results confirm the hemispherical dichotomy (east‐west and north‐south) in albedo/color/composition that has been observed by earlier studies. The presence of diogenite‐rich material in the southern hemisphere suggests that it was excavated during the formation of the Rheasilvia and Veneneia basins. Our lithologic mapping of HED regions provides direct evidence for magmatic evolution of Vesta with diogenite units in Rheasilvia forming the lower crust of a differentiated object.     

The formation of porphyry copper deposits

Copper is a moderately incompatible chalcophile element. Its behavior is strongly controlled by sulfides. The speciation of sulfur is controlled by oxygen fugacity. Therefore, porphyry Cu deposits are usually oxidized (with oxygen fugacities > ΔFMQ +2) (Mungall 2002; Sun et al. 2015). The problem is that while most of the magmas at convergent margins are highly oxidized, porphyry Cu deposits are very rare, suggesting that high oxygen fugacity alone is not sufficient. Partial melting of mantle peridotite even at very high oxygen fugacities forms arc magmas with initial Cu contents too low to form porphyry Cu deposits directly (Lee et al. 2012; Wilkinson 2013). Here we show that partial melting of subducted young oceanic slabs at high oxygen fugacity (>ΔFMQ +2) may form magmas with initial Cu contents up to >500 ppm, favorable for porphyry mineralization. Pre-enrichment of Cu through sulfide saturation and accumulation is not necessarily beneficial to porphyry Cu mineralization. In contrast, re-melting of porphyritic hydrothermal sulfide associated with iron oxides may have major contributions to porphyry deposits. Thick overriding continental crust reduces the “leakage” of hydrothermal fluids, thereby promoting porphyry mineralization. Nevertheless, it is also more difficult for ore forming fluids to penetrate the thick continental crust to reach the depths of 2–4 km where porphyry deposits form.     

Application of a wide-field electromagnetic method to shale gas exploration in South China

In an effort to reduce the shale gas exploration risks and costs, we applied the wide-field electromagnetic method (WFEM), because of its strong anti-interference capability, high resolution, ability to conduct exploration at large depths, and high efficiency, to the Bayan Syncline in the South Huayuan block, Hunan Province. We collected rock samples and analyzed their resistivity and induced polarization (IP) and built A series of two-dimensional models for geological conditions to investigate the applicability of WFEM to different geological structures. We also analyzed the correlation between TOC of shale and the resistivity and IP ratio to determine the threshold for identifying target formations. We used WFEM to identify the underground structures and determine the distribution, depth, and thickness of the target strata. Resistivity, IP, and total organic carbon were used to evaluate the shale gas prospects and select favorable areas (sweet spots) for exploration and development. Subsequently, drilling in these areas proved the applicability of WFEM in shale gas exploration.     

基于兴趣点（POI）大数据的东北城市空间结构分析

以东北三省36个城市为研究区,利用400余万条兴趣点行业分类大数据,采用核密度估计、标准差椭圆、区位熵等方法分析城市空间结构及其行业构成机制。研究发现,东北城市要素显著集聚,城市内部空间结构呈现集中团块型、分散组合型、线型、放射型特征以及多元复合类型;第二产业和房地产业呈现郊区化特征,各行业发展方向与东北大区域的经济轴线一致,多数行业尚未形成专业化功能区;第二产业与房地产业的离心发展对集中团块型城市的塑造作用不强,但对分散组合型城市空间结构的贡献较大。线型城市通常兼具多中心特征,放射型城市各行业仍偏向于向心聚集。     

快速Hartley变换及其在图象复原中的应用

本文把快速Hartley变换引入到天文数据处理中,提出了计算Cells坐标的公式,编制了FHT算法程序。FHT与Cooley—Tukey的FFT相似,但FHT是实变换,不存在复运算,因此比FFT快得多。利用DHT与离散Fourier变换(DFT)的关系,DFT可以由FHT求出。FHT将广泛地用于谱分析,信号处理,图像处理等领域。     

DISASTER ANALYSIS AND COUNTERMEASURES OF LAND SUBSIDENCE CAUSED BY COAL CUTTING IN CHINA

In recent years, many coal-producing countries have paid great attention to the land subsidence causedby coal cutting. In China, because of the dense population in coalfield areas, the land subsidence hazard is more seri-ous. After a brief analysis on the mechanism of land subsidence, this paper gives a comprehensive and systematical ac-count on all kinds of hazards caused by the land subsidence in China. The study shows that land subsidence has endan-gered land, buildings, traffic and communication lines, dykes and dams. It also causes damage to ecological and socialenvironment. In order to lessen the hazard of land subsidence, preventive measures should be taken to reduce the col-lapse amount, such as extraction with stowing, banded mining system, succession and coordination mining system, orhigh-pressure mudflow between rock strata. Measures of reinforcing or moving certain buildings should also be taken toreduce the destructive degree. In order to harness the subsidence land and bring them under control for fanning, mea-sures should be taken such as filling with spoil or fine breeze, excavating the deeper and covering the shallower land.     

Paleoproterozoic Extensional Structure and Its Controlling on Mineralization in the East of Liaoning Province

IntroductionThe area of eastern Liaoning is an importantmetal and nonmetal metallogenetic district in China,and the Liaohe group is one of the most importantstrata that hosts Pb, Zn, Au, B and Mg etcstratabound deposits. Up to now many geo1ogistssuch as Z…     

关于网络企业经济效益的评价理论研究

网络经济是相对于大工业经济而言的，其网络企业经济效益的评价，可以从网络企业成本及收益两个方面讨论，然后以投入产出比等五个方面来建立其评价指标体系。