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991.
对甘肃省3部CINRAD/CC型雷达近4年的雷达故障进行统计分析,作为雷达系统的主要故障部件,随着使用年限的增加,雷达数据传输系统的故障有明显的增多趋势.对引起故障的主要因素进行统计分析,提出了改进方法:基于标准网络的数据传输方式舍弃了原来的光纤系统;取消了基于光端机和复分接的通信方式,代以采用标准网络传输的通信方式;采用四创电子研发的终端软件(2.0版本),新增了集成的网络功能、用户权限功能、数据产品和图像产品全自动生成、数据文件的检索能力、语音报警等功能.改进后的雷达数据传输系统运行情况表明:网络型光纤通信系统减少了雷达数据传输故障,增强了系统的可靠性和稳定性;雷达数据的传输率和有效性也得到一定的提高,确保了新一代天气雷达的正常业务观测. 相似文献
992.
The High Energy Stereoscopic System (H.E.S.S.) is a system of Imaging Atmospheric Cherenkov Telescopes (IACTs) located in the Khomas Highland in Namibia. It measures cosmic gamma rays of very high energies (VHE; >100 GeV) using the Earth’s atmosphere as a calorimeter. The H.E.S.S. Array entered Phase II in September 2012 with the inauguration of a fifth telescope that is larger and more complex than the other four. This paper will give an overview of the current H.E.S.S. central data acquisition (DAQ) system with particular emphasis on the upgrades made to integrate the fifth telescope into the array. At first, the various requirements for the central DAQ are discussed then the general design principles employed to fulfil these requirements are described. Finally, the performance, stability and reliability of the H.E.S.S. central DAQ are presented. One of the major accomplishments is that less than 0.8% of observation time has been lost due to central DAQ problems since 2009. 相似文献
993.
994.
1 INTRODUCTION δ13C in organic matters from lacustrine sedi- ments varies with several factors including aquatic plants, vegetation type in the catchment, atmos- pheric CO2 concentration, climate (temperature and precipitation), and properties of water, … 相似文献
995.
Abstract 40 Ar/39 Ar step-heating and single-grain laser fusion ages from phengites from the polydeformed and polymetamorphosed blueschist-greenschist facies Nome Group fall into two groups. Samples from the upper part of the structural section that have experienced a relatively weak metamorphic and deformational post-blueschist facies overprint and one sample from the Cape Nome orthogneiss yield plateau ages of 116-125 Ma. More intensely overprinted samples yield hump-shaped spectra with minimum ages of 123 Ma and maximum ages of 334 Ma. Samples with hump-shaped spectra are derived from a greater structural depth than most samples with plateau ages. Unreasonably old maximum ages from some of the disturbed spectra suggest that the hump-shaped spectra result from the incorporation of excess 40 Ar. This interpretation conflicts with previous interpretations of similarly disturbed spectra from the Brooks Range, which have been argued to provide minimum ages for blueschist facies metamorphism. Since the maximum temperatures achieved by all samples were probably above the blocking temperature of Ar in phengite, the 116-125 Ma plateau ages are a minimum age for blueschist facies metamorphism on the Seward Peninsula, Alaska. 相似文献
996.
按溃变理论[1]的不连续或非均匀信息不仅可以预测天气系统的移动性变化和转折性变化,也可以预测降水等天气现象。并已被多次历史例案和应用实践所验证。为了便于投入业务运用,我们利用数据库系统,实现了体现资料信息非均匀和不连续的广义参数在微机、填图机上的自动化处理,完成了收报、计算和填图分析的自动化。本方法体现了预报工具的改革也充分地利用了现有的资料资源 相似文献
997.
We report on spectro-imaging infrared observations of Jupiter's auroral zones, acquired in October 1999 and October 2000 with the FTS/BEAR instrument at the Canada-France-Hawaii Telescope. The use of narrow-band filters at 2.09 and 2.12 μm, combined with high spectral resolution (0.2 cm−1), allowed us to map emission from the H2S1(1) quadrupole line and from several H3+ lines. The H2 and H3+ emission appears to be morphologically different, especially in the north, where the latter notably exhibits a “hot spot” near 150°-170° System III longitude. This hot spot coincides in position with the region of increased and variable hydrocarbon, FUV and X-ray emission, but is not seen in the more uniform H2S1(1) emission. We also present the first images of the H2 emission in the southern polar region. The spectra include a total of 14 H3+ lines, including two hot lines from the 3ν2-ν2 band, detected on Jupiter for the first time. They can be used to determine H3+ column densities, rotational (Trot) and vibrational (Tvib) temperatures. We find the mean Tvib of the v2=3 state to be lower (960±50 K) than the mean Trot in v2=2 (1170±75 K), indicating an underpopulation of the v2=3 level with respect to local thermodynamical equilibrium. Rotational temperatures and associated column densities are generally higher and lower, respectively, than inferred previously from ν2 observations. This is a likely consequence of a large positive temperature gradient in the sub-microbar auroral atmosphere. While the signal-to-noise is not sufficient to take full advantage of the 2-D capabilities of the observations, the search for correlations between line intensities, Tvib and column densities, indicates that variations in line intensities are mostly due to correlated variations in the H3+ column densities. The thermostatic role played by H3+ at ionospheric levels may provide an explanation. The exception is the northern “hot spot,” which exhibits a Tvib about 250 K higher than other regions. A partial explanation might invoke a homopause elevation in this region, but a fully consistent scenario is not yet available. The different distributions of the H2 and H3+ emission are equally difficult to explain. 相似文献
998.
YANG Zisheng LIU Yansui BAO Guangjing LI Zhiguo HE Yimei 《山地科学学报》2006,3(3):237-246
The rocky desert in a karst area directly causes the lack of soil, water and forest, hence leading to the poverty there. In 1990, the villagers from the Muzhe Village in Benggu Township, Xichou County, Yunnan declared a war against rocky desert in an attempt to ask the fields for more yields. They invented a distinctive land rehabilitation and sustainable use pattern called "transforming heaven and earth" that had been practiced in Southwest China's karst areas. The key mechanism of the pattern was to develop terraced fields with well conserved soil, water and fertility by exploding rocks in the fields, building stone walls, gathering more soil, and improving soil quality and productivity for the fields in combination with building of irrigation facilities and roads, as well as with forestation and agriculture structure adjustment. The purpose of the pattern was to alleviate poverty in the karst areas by improving soil productivity and promoting agricultural development. A typical area was studied with the help of Participatory Rural Appraisal (PRA) and the pattern was carried out there for fifteen years, have produced excellent ecological benefits and good economic benefits. Its application in the area approved that it was a sustainable land use pattern for rocky desert areas. 相似文献
999.
Rui-Qing Mao Qin Zeng Purple Mountain Observatory Chinese Academy of Sciences Nanjing National Astronomical Observatories Chinese Academy of Sciences Beijing 《中国天文和天体物理学报》2004,4(5):440-454
The massive star forming region S 233 IR is observed in the molecular lines CO J = 2-1, 3-2, NH3 (1,1), (2,2) and the 870#m dust continuum. Four submillimeter continuum sources, labelled SMM 1-4, are revealed in the 870μm dust emission. The main core, SMM1, is found to be associated with a deeply embedded near infrared cluster in the northeast; while the weaker source SMM2 coincides with a more evolved cluster in the southwest. The best fit spectral energy distribution of SMM1 gives an emissivity of β = 1.6, and temperatures of 32 K and 92 K for the cold- and hot-dust components. An SMM1 core mass of 246 M⊙ and a total mass of 445 M⊙ are estimated from the 870μm dust continuum emission.SMM1 is found to have a temperature gradient decreasing from inside out, indicative of the presence of interior heating sources. The total outflow gas mass as traced by the CO J = 3-2 emission is estimated to be 35 M⊙. Low velocity outflows are also found in the NH3 (1,1) emission. The non-thermal dominant NH3 line width as well as the substantial core mass suggest that the SMM1 core is a “turbulent,massive dense core”, in the process of forming a group or a cluster of stars. The much higher star formation efficiency found in the southwest cluster supports the suggestion that this cluster is more evolved than the northeast one. Large near infrared photometric variations found in the source PCS-IR93, a previously found highly polarized nebulosity, indicate an underlying star showing the FU Orionis type of behavior. 相似文献
1000.
Microfossils in isolation basin sediments are frequently used to reconstruct sea‐level change, but preservation problems and non‐analogue situations can limit their usefulness. Here we investigate the potential of stable carbon isotopes (δ13C) and C/N ratios from bulk organic matter, as an alternative proxy of salinity within isolation basin sediments from a basin in northwest Scotland. Within the Holocene sediment δ13C and C/N are determined largely by the mean weighted values of the predominant source of the organic material. Analysis of modern materials and comparison with the diatom record shows that the marine parts of the sequence are dominated by high δ13C and variable C/N. In the fresh water sequences the organic material is a mixture of both freshwater aquatic and terrestrial plant input that have relatively low δ13C and high C/N. The application of δ13C and C/N ratios in the studied basin in general follow the environmental change recorded by the diatoms and shows the potential of bulk organic matter in the investigation of salinity change in isolation basins. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献