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401.
20世纪90年代中期以来中国县域旅游研究进展与展望 总被引:1,自引:0,他引:1
采用Pearson Correlation分析法对1995-2010年我国县域旅游研究重要文献进行系统评述,初步构建了我国县域旅游理论体系;研究内容主要包括发展、规划、开发、资源、市场、形象、产品和方法研究8个领域21个视角,研究方法以现象描述和数理统计方法为主,但仍存在着理论研究视角、实证研究对象和研究方法选择较单一等问题;今后应分别从发展、规划、开发、要素和研究方法等方面的28个重要方向拓宽和延伸我国县域旅游的理论与实证研究。 相似文献
402.
分析了乌苏站1998~2001年(4~10月)E-601B型与小型蒸发器4年蒸发量对比观测资料,运用统计方法进行了相关性研究,并应用比值法和多元线性回归方法,得出了两种蒸发量之间的折算系数,计算出了乌苏站1971~1997年4~10月逐月E-601B型蒸发量估算值,为当地的气候研究和气象服务提供重要依据。 相似文献
403.
侧视雷达影像距离-共面模型严密定位 总被引:1,自引:1,他引:0
本文对现有侧视雷达遥感影像的几何构像模型在摄影测量应用中的不足进行了理论分析,以外方位元素作为定向参数,依次建立了像点坐标显函数形式的距离-共面(R-Cp)方程、地心直角坐标系中星载侧视雷达影像的距离-共面方程、以及星载侧视雷达遥感影像的严密定位模型,并进行了稀少控制点条件的星载TerraSAR-X影像定位试验。理论和试验表明,本文所建立的R-Cp严密定位模型,使得雷达影像像点量测坐标作为摄影测量观测值的属性得到体现,容易吸收和利用光学遥感影像基于共线方程模型发展起来的成熟的数字摄影测量数据处理方法,有利于提高雷达遥感影像摄影测量数据处理的严密性、稳定性、可靠性及数据处理效率。 相似文献
404.
405.
北京夏季日最大电力负荷预报模型建立方法探讨 总被引:2,自引:1,他引:1
为了探索夏季(6~8月)日气象负荷的最佳分离方式和引起日最大电力负荷波动的主要因子,以及建立预报模型最佳个数,基于北京市2005~2010年逐日最大电力负荷和同期的气象资料,分析了北京地区日最大电力负荷的变化规律,采用不同方法将气象负荷从夏季日最大电力负荷中分离出来,分析北京夏季气象负荷与气温、相对湿度、降水及炎热指数、高温持续日数、炎热日数持续时间、前一日气象负荷等因子之间的关系,并基于2005~2009年夏季逐日气象负荷和其主要影响因子采用逐步回归方法建立日最大电力负荷的预报模型,将2010年夏季北京日最大电力负荷作为预报效果的独立样本检验。结果显示:2005~2010年,北京逐日最大电力负荷具有明显的线性增长趋势,夏季日最大电力负荷具有显著的星期效应;与去掉逐年夏季日最大电力负荷趋势和夏季平均日最大电力负荷趋势相比,去掉全年逐日最大电力负荷变化趋势的夏季日气象负荷预报模型的拟合能力更优;北京夏季日气象负荷与当日气温的相关系数最高,与前一日气象负荷也关系密切;利用前一日相对气象负荷和当日气象要素一周逐日分别建立预报模型的拟合和预测效果较好。 相似文献
406.
407.
济南市一次持续大雾过程分析 总被引:1,自引:1,他引:0
利用常规气象观测资料对2007年12月20-23日济南市一次持续大雾天气过程的大尺度天气背景、地面气压场、温度对数压力图以及单站气象要素进行了分析,结果表明:雾是在稳定的大气层结下出现的天气现象,根据大气稳定层结的状况及变化,可以判断大雾天气的有无及生消时间;近地面逆温和低空逆温同时存在,表明大气层结非常稳定,近地面逆温有利于近地面层水汽积累,低空逆温使近地面层水汽不易扩散而聚集,有利于近地面层维持潮湿,持续几天出现大雾;连续几天大气层结都处于稳定状态,地面风力很小,这些都限制了近地面层的水汽向外耗散,底层相对湿度较大,为大雾的形成提供了充沛的水汽条件. 相似文献
408.
In Cisjordan, surface- and groundwater flow are either towards the Jordan Valley-Dead Sea-Arava Valley (the Rift) or the Mediterranean Sea. Due to upstream exploitation by riparians to the Jordan River, the historical annual flow, which fluctuated between 250 and 1100 Mm3, has declined to a mere 100-200 Mm3. The remaining flow south of Lake Kinneret is highly polluted and heavily loaded with salts. Lake Kinneret (Sea of Galilee) is one of the major water resources in the area. Annually, between 200 and 700 Mm3 reach the Lake as surface and groundwater flow. The relatively high salinity of the Lake is caused by thermomineral water discharging from springs and seepages located onshore and on the bottom of the Lake. The main factors causing deterioration of the groundwater quality in the Rift are of geogenic character. These are different types of brines, whose outflow and penetration into freshwater aquifers was triggered by overpumpage. Contemporary encroachment of seawater caused by intensive water exploitation in the Coastal Plain is manageable and reversible. However, due to lack of hydrogeological evidence, no such statement can be made about the circulation of seawater beneath the Coastal Plain and into the deep-seated Yarkon-Taninim aquifer or the upflow of brines in the Rift.The flow regimes of the different brine bodies could not be elucidated. Whether each such brine-body flows by its particular hydrological regime or whether the movement of the different bodies is intradependent or interdependent with the regional movement of fresh groundwater, remain open questions. Therefore, sustainable development of groundwater resources is clearly dependent on the elucidation of the relationship between changes in the pressure of the brine with depth and its relationship to the overlying freshwater.The average total annual recharge of all water sources in Cisjordan is 1820 Mm3, which means that the total production of water must be managed within the limits of this annual volume. During drought years, total groundwater extraction exceeds the safe yield, causing drastic lowering of water levels and upflow of saline waters from greater depths.Because of the structural complexity of aquifers and hydrochemical variability of the numerous groundwater bodies, new hydrochemical methods have been developed for the identification of groundwater bodies and for the elucidation of their origins. These methods combine macrochemical, microchemical, and isotopic evidences. By combining distribution patterns of rare earths, yttrium and stable isotopes, a complete picture of catchment lithology and the altitude and latitude of precipitation could be obtained.The area west of the Jordan River is characterized by the occurrence of transboundary surface- and groundwater basins in which fresh and saline water and brines flow across political borders between Israel and the Palestinian Authority. It is very difficult to assess separately the annual safe yield of water resources for each of the two national entities. Neither country may dispose independently of its waters and is usually at the mercy of the other riparian. There is as yet no general multilateral international treaty in force allocating the water resources of international watercourses. At present there are two rules for the management of the waters of an international drainage basin—the rule of Equitable Distribution, and the obligation Not to Cause Significant Harm. The rules of equitable distribution have tended to focus on the issue of quantities of water rather than on quality of water, which is really relevant to the issue of equitable distribution. Future negotiations on the uses of the basin will need to deal with issues of characteristic salinities and geochemical features and on their impact on equitable sharing of water resources. 相似文献
409.
Benjamin Kaeser Bettina Olker Angelika Kalt Rainer Altherr Thomas Pettke 《Contributions to Mineralogy and Petrology》2009,157(4):453-472
Garnet-bearing and garnet-free pyroxenite xenoliths from Quaternary basanites of Marsabit, northern Kenya, were analysed for
microstructures and mineral compositions (major and trace elements) to constrain the thermal and compositional evolution of
the lithospheric mantle in this region. Garnet-bearing rocks are amphibole-bearing websterite with ~5–10 vol% orthopyroxene.
Clinopyroxene is LREE-depleted and garnet has high HREE contents, in agreement with an origin as cumulates from basaltic mantle
melts. Primary orthopyroxene inclusions in garnet suggest that the parental melts were orthopyroxene-saturated. Rock fabrics
vary from weakly to strongly deformed. Thermobarometry indicates extensive decompression and cooling (~970–1,100°C at ~2.3–2.6 GPa
to ~700–800°C at ~0.5–1.0 GPa) during deformation, best interpreted as pyroxenite intrusion into thick Paleozoic continental
lithosphere subsequently followed by continental rifting (i.e., formation of the Mesozoic Anza Graben). During continental
rifting, garnet websterites were decompressed (garnet-to-spinel transition) and experienced the same P–T evolution as their host peridotites. Strongly deformed samples show compositional overlaps with cpx-rich, initially garnet-bearing
lherzolite, best explained by partial re-equilibration of peridotite and pyroxenite during deformation and mechanical mingling.
In contrast, garnet-free pyroxenites include undeformed, cumulate-like samples, indicating that they are younger than the
garnet websterites. Major and trace element compositions of clinopyroxene and calculated equilibrium melts suggest crystallisation
from alkaline basaltic melt similar to the host basanite, which suggests formation in the context of alkaline magmatism during
the development of the Kenya rift.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
410.
Sub-micron scale distributions of trace elements in zircon 总被引:2,自引:1,他引:1
Amy E. Hofmann John W. Valley E. Bruce Watson Aaron J. Cavosie John M. Eiler 《Contributions to Mineralogy and Petrology》2009,158(3):317-335
Sub-micron scale zoning of Ti concentrations and correlations between concentrations of Ti and other trace elements (P, Ce,
and Y) and cathodoluminescent (CL) banding is observed in natural zircons. Ion images were made using the Caltech Microanalysis
Center’s CAMECA NanoSIMS 50L with an O− primary beam focused to ~300 nm on the sample surface. The high spatial resolution of this technique allows for interrogation
of chemical variations at or below the scale of CL banding in natural zircons. Images produced in this manner display two
types of correlations among Ti, P, Ce, and Y (which appears to be a proxy for CL intensity): strong (correlation coefficients
>0.8) and subtle (correlation coefficients ~0.15–0.4). Strongly correlated images, which display Ti variations of ca. a factor
of 3 between adjacent CL bands and overall elevated trace element concentrations in CL-dark bands, were found within an oscillatory-zoned,
trace element enriched sector of a CL sector-zoned zircon. Three possible causes for such correlations include: temperature-dependent
equilibrium partitioning, trace element partitioning limited by diffusion in the host melt and surface-controlled, non-equilibrium
growth. Comparison of our data with the expected results of these processes suggests that: (1) Ti partitioning in zircon is
dependent upon non-equilibrium effects in addition to temperature and/or (2) the incorporation of elements that co-vary with
Ti in zircon (e.g., Y, P and Ce) is also temperature-dependent. Sub-micron scale, high-Ti regions are also found within Proterozoic
Adirondack and >4 Ga Jack Hills zircons as well as trace element enrichments (including Ti) along cracks within Jack Hills
zircons. 相似文献