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911.
云南天文台1m望远镜终端之一的暗天体分光仪和照相机具有4种运行模式:缩焦照相机、无缝多目标光谱仪、有缝光谱仪和星冕仪。这4种运行模式能在几分钟的时间内相互转换,高效快速和灵活方便。该仪器的光学质量优秀,光学系统消像差,特别是消色差。由于光学系统消色差,所成像的低色散光谱在404.6~766.5nm全波段尖锐平直。在多色测光时,各测光波段的像面位置不变,同时兼有大视场的优点,可提高测光精度和测光效率。 相似文献
912.
Modal synthesis of high-frequency waves in Scotland 总被引:1,自引:0,他引:1
913.
914.
915.
The organizational separation of management and other quaternary activities from production operations in American manufacturing has resulted in a divergent pattern of production and headquarter locations. We examine the external control relationships that arise from this separation between headquarter location and branch plant operations in nonmetropolitan Kentucky. Although corporate headquarters have diffused to the Sunbelt, no shift was found in the corporate control of branch plants in Kentucky. Nonmetropolitan manufacturing in Kentucky was oriented toward the metropolitan centers of the traditional manufacturing belt rather than the newer corporate centers of the South. Also control relationships are more likely to be local among smaller factories. Large plants having more autonomy in production or producing finished goods were more likely to be owned by a distant firm located in a large SMSA. 相似文献
916.
Methodological Development of the Conditional Sampling Method. Part II: Quality Control Criteria of Relaxed Eddy Accumulation Flux Measurements 总被引:1,自引:1,他引:0
A.?K.?Fotiadi F.?Lohou A.?Druilhet D.?Ser?aEmail author F.?Said P.?Laville A.?Brut 《Boundary-Layer Meteorology》2005,117(3):577-603
Determination of biosphere–atmosphere exchanges requires accurate quantification of the turbulent fluxes of energy and of
a wide variety of trace gases. Relaxed Eddy Accumulation (REA) is a method that has received increasing attention in recent
years, because it does not require any rapid sensor for the scalar measurements as the Eddy Correlation method (EC) does.
As in all micrometeorological studies, REA measurements in the atmospheric surface layer are valid under some restrictive
conditions so as to be representative of a specific ecosystem. These conditions are the homogeneity of the underlying surface,
stationary and horizontally homogeneous turbulence. For most experiments these conditions are not fully satisfied. Data uncertainties
can also be related to not fulfilling the method principles or to the technical characteristics of the REA system itself.
In order to assess REA measurement quality, a methodological approach of data analysis is developed in this study. This methodological
analysis is based on the establishment of criteria for data quality control. A set of them, deduced from the mean and turbulent
flow, are called ‘Dynamic criteria’ and are designated to control the stationarity and homogeneity of the w function and the validation of Taylor’s hypothesis. A second set (‘REA operational criteria’) is designed to check the sampling
process and, more precisely, the homogeneity of the negative and positive selection process throughout the sampling period.
A third set of criteria (‘Chemical scalar criteria’) concerns the scalar measurements. Results of the criteria application
to data measured at two different experimental sites are also presented. Cut-off limits of criteria are defined based on their
statistical distribution and shown to be specific for each site. Strictness of each criterion, defined by the percentage of
flagged samples, is analysed in conjunction with the meteorological conditions and atmospheric stability. It is found that
flagged samples mainly correspond to neutral and stable nocturnal conditions. During daytime, nearly free convection conditions
can also yield poor quality data. 相似文献
917.
918.
Provenance of Palaeozoic sandstones from the Carnic Alps (Austria): petrographic and geochemical indicators 总被引:1,自引:0,他引:1
An integrated approach of petrographic analysis, whole rock geochemistry and microprobe analysis has been applied to obtain information on the geodynamic development and the provenance for Ordovician to Permian siliciclastic successions exposed within the Carnic Alps (Austria). Sandstone detrital mode and geochemical results refine previous geodynamic interpretations. Late Ordovician samples indicate a stable craton and recycled orogenic and, possible, extensional setting. The Early Carboniferous is interpreted to represent a compressional environment, followed by a Late Carboniferous molasse-type foreland basin, and a Permian extensional geodynamic setting. Contrasting geochemical patterns of post-Variscan and Permian sequences suggest a rift setting. Electron microprobe data of detrital white mica also indicate changes in the provenance. Compositional data reflect a shift from low- to medium-grade metamorphic (Ordovician) to high-grade metamorphic (Carboniferous) to low- to medium-grade metamorphic and plutonic source rocks (Permian). Additionally, our data show that various chemical discrimination diagrams do not include all possible ranges of sandstones, and that high contents of detrital mica and ultra-stable heavy minerals may cause misclassification. Consequently, we propose the use of multi-method approach for provenance studies, including the control of geochemical data by modal analysis and heavy mineral investigations. 相似文献
919.
地图符号化中的几个关键问题研究 总被引:9,自引:0,他引:9
从应用的角度,对多地图符号库的组织和高效访问机制进行了研究.首次引入显示控制样式的概念,以解决不同比例尺下地图的屏幕显示效果问题,同时基于显示控制样式管理,研究了屏幕显示效果与打印效果统一的问题.文中采用地图符号库索引加缓存符号描述信息的机制,提高了访问多地图符号库中描述信息的速度;采用显示控制样式控制要素层在不同比例尺下是否显示、显示的详细程度及采用哪种显示样式;采用双显示控制样式库解决屏幕显示效果和打印效果的统一问题.实践证明,该研究成果可以很好地解决多地图符号库管理和高效访问问题,改善地图的显示效果和控制地图的显示速度;另外还可以保证地图屏幕显示和打印输出效果的统一. 相似文献
920.
水泥混凝土路面施工质量管理 总被引:2,自引:0,他引:2
加强混凝土路面施工全面质量管理,一定要严格按国家有关规范和评定标准施工和验收。加强水泥混凝土路面施工管理和质量控制,对加快道路建设步伐,提高工程质量,节省投资,更好地服务于社会经济发展具有十分重要的意义。 相似文献