景观生态分类与制图浅议

本文在查阅分析大量文献和前人研究的基础上 ,对目前景观生态分类和景观制图作了详细的对比分析 ,认为景观分类需要结合实际区域现状 ,采用逐级分类的方法 ;同时利用 ETM遥感影像为数据源 ,以天山北麓为示范区.研制其土地利用土地覆盖变化的景观类型图。     

中国1∶100万景观生态制图设计

中国1∶100万景观生态图系借鉴国内外传统景观制图方法和制图规范,在遥感、地理信息系统先进技术的支持下,设计研制其制图方法、制图内容、样图和技术流程,同时提出初步的景观分类系统,为今后编制中国1∶100万景观生态图奠定基础。     

弧后盆地的形成与演化探讨：以东亚陆缘区为例

通过对弧后盆地大地构造体制的讨论，作者认为基属活化作用的产物根据地质，地球物理，地球化学等资料的分析，作者提出结论认为，由于东亚岛弧系岩石圈的均衡作用及海沟外侧冷却大洋岩石圈块体的下沉拖曳牵引等作用，使软流圈在岛弧系下方发生分异，这种分异作用带动东亚陆缘向东扩张，从而产生弧后的张开。     

基于BSP-15下低码率实时H.264编码器的实现

根据低码率实时应用领域的特点,对H.264的新编码特性进行了分析选择,提出了一套合适的编码方案,在编码性能和编码复杂度之间平衡;利用BSP-15 DSP芯片硬件的特点,设计了H.264编码器,并在DSP上实现.实验结果表明,H.264编码器对CIF大小的图像实现了实时编码.     

中国西北部“4.5”沙尘暴过程中尺度低压的数值模拟

利用改进型ＰＳＵ／ＮＣＡＲ中尺度数值模式（ＭＭ４标准版），取模式水平格距４０ｋｍ，４６×６１网格，垂直方向ａ取１５层，即从地面到模式顶（１００ｈＰａ），σ＝０．０、０．１、０．２、０．３、０．４、０．５、０．６、０．７、０．７８、０．８４、０．８９、０．９３、０．９６、０．９８、０．９９、１．００，采用ＮＣＡＲ的３０＇×３０＇地形资料，以常规观测资料作为初始场，较好地模拟了此次沙尘暴过程的海平面气压的演变和分布，特别是张掖、柴达本盆地以及敦煌附近的三个中低压。同时，模拟了张掖中低压与蒙古冷高压之间的甘肃河西沙尘暴东大风。敏感性试验表明，沙尘暴中低压的形成发展主要是受于物理过程制约；沙尘暴中尺度系统的研究与暴雨中尺度系统的研究是有区别的，积云对流参数化并不是特别重要，在设计研究沙尘暴的数值模式中，应当合理地处理其他的热力、动力过程及大气外强迫源的作用。模式水平格距、地形真实程度对模拟中低压的位置、中心强度有重要贡献；下垫面变化中低压强度有一定影响。张掖热低压的形成发展主要是在有利的环境形势下，特殊地势起了重要作用，表现为直接动力强迫和间接热力强迫。     

Geophysical constraints on mesozoic disruption of North China Craton by underplating‐triggered lower‐crust flow of the Archaean lithosphere

The mechanism of the disruption, both lithospheric thinning and oceanization of the commonly accepted long‐term‐stable Archaean craton, is still an open question. The available models, all imply a bottom to top process. With the construction of a 1660‐km‐long transect across the eastern North China Craton (NCC), we demonstrate that both the P‐wave velocity and density in the lowermost crust beneath the central section are significantly higher than in the corresponding parts of the south and north sections on the transect. These features are interpreted as geophysical signature of lower crustal underplating, which supplies sufficiently high gravitational potential energy to trigger lateral flow of the lower crust. This magma underplating‐triggered bilateral lower crust flow may facilitate the lithospheric thinning by means of asthenosphere upwelling and decompression melting, which infill the gap produced by the lower crust flow. The underplating‐triggered lower crustal flow can provide an alternative mechanism to explain the NCC lithosphere disruption, which highlights the crustal feedback to Archaean lithosphere disruption, from top to bottom.     

内蒙古科尔沁右翼中旗协和尔斯德中生代火山沉积地层时代研究

内蒙古科尔沁右翼中旗协和尔斯德一带出露一套中生代地层,岩石组合主要为酸性火山碎屑岩、火山碎屑沉积岩夹碎屑沉积岩及酸性火山熔岩。1∶50000区调依据在该套地层上部层位发现的木化石组合确定其时代为中—晚侏罗世,结合岩石组合,将该套地层划分为上侏罗统满克头鄂博组。为了准确厘定该套地层时代,为木化石延限研究及区域生物地层划分对比提供依据,本次研究在低于产木化石层位的酸性火山碎屑岩中采取了锆石测年样品(LA-ICP-MS),获得锆石U-Pb年龄(165±1)Ma,时代为中侏罗世。同时采取了侵入该套地层的斑状细晶闪长岩测年样品,获得锆石年龄(131±1)Ma,限定了地层形成的上限年龄。根据岩性组合的区域对比、测年结果、木化石组合时限、地层产状特征,认为该套地层应划为中侏罗统新民组,是突泉火山-沉积盆地充填物的一部分。     

Carbon dioxide emission reduction quota allocation study on Chinese provinces based on two-stage Shapley information entropy model

Chinese central government made a commitment to achieve a 40–45% reduction in carbon dioxide (CO₂) per unit of GDP by 2020 compared with 2005. This targeted reduction was allocated averagely among all the provinces rather than individually according to different situations of each province. Though some research has been done regarding this rough allocation, two shortcomings in previous studies exist: Firstly, CO₂ marginal abatement cost (MAC) has been ignored as one of the CO₂ emission reduction allocation indexes. Secondly, either subjective or objective method has been used rather than comprehensively of both subjective and objective method to calculate the weight of each index in the previous studies. In order to fill the gaps, this paper builds a two-stage Shapley information entropy model to allocate CO₂ emission reduction quota among the Chinese provinces based on the equity and efficiency principles. Afterward, three CO₂ emission reduction quota allocation scenarios have been proposed. The results show that the CO₂ MAC is an indispensable index in CO₂ emission reduction quota allocation, because its value of CO₂ Shapley information entropy is the highest among five indexes. CO₂ emission reduction quota of lower-MAC provinces should be allocated larger, while the quota of higher-MAC provinces should be allocated smaller. Therefore, two suggested policies have been proposed: First, differential CO₂ emission reduction quota allocation should be proposed. Second, synergetic development should be promoted.     

Network-based triple-frequency carrier phase ambiguity resolution between reference stations using BDS data for long baselines

Network-based ambiguity resolution (AR) between reference stations is the prerequisite to realize a precise real-time kinematic positioning service. With the help of BDS triple-frequency signals, we can efficiently deal with the ionospheric delay and tropospheric delay, and achieve rapid and reliable AR. To overcome the inaccurate ionospheric delay estimated by the geometry-free three carrier ambiguity resolution (GF TCAR) technique, which leads to failure in the original ambiguity resolution, we propose an ionospheric-free (IF) TCAR method to resolve the ambiguity between the reference stations over long baselines. Taking full advantage of the known positions of the reference stations, the easily resolved extra-wide-lane (EWL) ambiguity, and the IF phase combinations, we can reliably fix the wide-lane (WL) ambiguity. A Kalman filter is applied to estimate precise IF ambiguities and the original ambiguity is resolved with the fixed WL ambiguity. A numerical analysis with triple-frequency BDS data from three long baselines of a CORS network is provided to compare the AR performance of GF TCAR with that of IF TCAR. The results show that both methods can reliably resolve the WL ambiguity with a remarkable correctly-fixed rate of higher than 99%, and the reliably-fixed rates of the IF TCAR slightly increase from 92.19, 94.67 and 94.61–98.26, 99.54 and 97.51% for the three baselines. Herein “correctly-fixed” and “reliably-fixed” mean the difference between the float ambiguity and the true one are less than ± 0.5 and ± 0.25 cycles, respectively. On the other hand, the AR performance of the original signals with the IF TCAR method is much better than that with the GF TCAR method attaining a 100% correctly-fixed rate, while the GF TCAR method can hardly fix the original ambiguity with the largest bias being as much as 4 cycles because of the amplified systematic bias.     

An improved ionosphere interpolation algorithm for network RTK in low-latitude regions

A traditional interpolation algorithm with the linear interpolation method (LIM) using a fixed number of reference stations is widely used in network RTK to obtain the ionospheric delays for the users. In low-latitude regions, where the ionosphere is relatively active, however, large interpolation errors exist, especially for satellites at low elevation angles. Considering the characteristics of “coinciding ionospheric pierce points (CIPPs)” with a similar nature of ionospheric delays, an improved interpolation algorithm is proposed. In this algorithm, all stations with CIPPs are used to establish the interpolation model; thus, more precise interpolation model is achieved. To validate the performance of the proposed algorithm, data from some reference stations in Guangdong Province of China were used, and the results are compared with those with the traditional interpolation algorithm. Numerical analysis shows that the interpolation accuracy of the proposed algorithm increases by 10–30% compared with the traditional one. Since the number of reference stations is flexible, the proposed algorithm can also balance the model accuracy with the computation burdens. In addition, the proposed algorithm is less affected by the selection of master reference station. In terms of network RTK on-the-fly positioning, the time-to-first-fix is reduced when replacing the traditional interpolation algorithm with the proposed one.