Rehabilitation and Sustainable Use Pattern of Rocky-desertified Land in Southwest China＇s Poverty-stricken Karst Mountainous Areas ——A Case Study in Benggu Township, Xichou County, Yunnan, China   总被引：4，自引：1，他引：3  

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   

Spectral analysis of the background in ground-based, long-slit spectroscopy     

Frédéric Zagury 《Journal of Astrophysics and Astronomy》2005,26(4):377-394

This paper examines the variations, because of atmospheric extinction, of broad-band visible spectra, obtained from long-slit spectroscopy, in the vicinity of some stars, nebulae, and one faint galaxy.  相似文献   

哈雷彗星主尾流的研究     

赵海斌  胡中为  王建中  侯振宇 《天文学报》2002,43(1):66-74

哈雷彗星在日彗距较大时出现长而直的主彗尾（尾流），这是很有趣的。尾流一般是指等离子体尾流；但是，当地球接近彗星轨道面时，尘埃尾流可能叠加到主彗尾上。在一般感光波段宽的彗星底片上很难区分这两种尾流。本文选取哈雷彗星在不同日彗距的5条主尾流，作了光度测量和比较分析。得出沿各尾轴及其垂直方向几个截面的亮度分布、亮度半极大全宽、尾轴的视风差角和真风差角及彗尾长度。在所分析的蓝敏底片上，过近日点前的2个尾流肯定是等离子体尾流，而5个尾流的相似性以及其他证据说明它们主要都是等离子体尾流，尘埃彗尾的污染是次要的。  相似文献   

HT Camelopardalis: the simplest intermediate polar spin pulse     

P. A. Evans  Coel Hellier 《Monthly notices of the Royal Astronomical Society》2005,359(4):1531-1536

The intermediate polar (IP) HT Cam is unusual in that it shows no evidence for dense absorption in its spectrum. We analyse an XMM–Newton observation of this star, which confirms the absence of absorption and shows that the X-ray spin pulse is energy independent. The modulation arises solely from occultation effects and can be reproduced by a simple geometrical model in which the lower accretion footprint is fainter than the upper one.
We suggest that the lack of opacity in the accretion columns of HT Cam, and also of EX Hya and V1025 Cen, results from a low accretion rate owing to their being below the cataclysmic variable period gap.  相似文献   

Molecular Gas and Dust in the Massive Star Forming Region S 233 IR     

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   

The Zamama-Thor region of Io: Insights from a synthesis of mapping, topography, and Galileo spacecraft data     

David A. Williams  Laszlo P. Keszthelyi  Moses P. Milazzo  Julie A. Rathbun 《Icarus》2005,177(1):69-88

We have studied data from the Galileo spacecraft's three remote sensing instruments (Solid-State Imager (SSI), Near-Infrared Mapping Spectrometer (NIMS), and Photopolarimeter-Radiometer (PPR)) covering the Zamama-Thor region of Io's antijovian hemisphere, and produced a geomorphological map of this region. This is the third of three regional maps we are producing from the Galileo spacecraft data. Our goal is to assess the variety of volcanic and tectonic materials and their interrelationships on Io using planetary mapping techniques, supplemented with all available Galileo remote sensing data. Based on the Galileo data analysis and our mapping, we have determined that the most recent geologic activity in the Zamama-Thor region has been dominated by two sites of large-scale volcanic surface changes. The Zamama Eruptive Center is a site of both explosive and effusive eruptions, which emanate from two relatively steep edifices (Zamama Tholi A and B) that appear to be built by both silicate and sulfur volcanism. A ∼100-km long flow field formed sometime after the 1979 Voyager flybys, which appears to be a site of promethean-style compound flows, flow-front SO₂ plumes, and adjacent sulfur flows. Larger, possibly stealthy, plumes have on at least one occasion during the Galileo mission tapped a source that probably includes S and/or Cl to produce a red pyroclastic deposit from the same vent from which silicate lavas were erupted. The Thor Eruptive Center, which may have been active prior to Voyager, became active again during the Galileo mission between May and August 2001. A pillanian-style eruption at Thor included the tallest plume observed to date on Io (at least 500 km high) and new dark lava flows. The plume produced a central dark pyroclastic deposit (probably silicate-rich) and an outlying white diffuse ring that is SO₂-rich. Mapping shows that several of the new dark lava flows around the plume vent have reoccupied sites of earlier flows. Unlike most of the other pillanian eruptions observed during the Galileo mission, the 2001 Thor eruption did not produce a large red ring deposit, indicating a relative lack of S and/or Cl gases interacting with the magma during that eruption. Between these two eruptive centers are two paterae, Thomagata and Reshef. Thomagata Patera is located on a large shield-like mesa and shows no signs of activity. In contrast, Reshef Patera is located on a large, irregular mesa that is apparently undergoing degradation through erosion (perhaps from SO₂-sapping or chemical decomposition of sulfur-rich material) from multiple secondary volcanic centers.  相似文献   

GPS实时监测和预报电离层电子含量   总被引：7，自引：2，他引：5  

金双根  J.WANG  章红平  朱文耀 《天文学报》2004,45(2):213-219

GPS能高精度地实时监测电离层总电子含量(TEC)变化，对纠正单频GPS接收机电离层延迟和监测电离层活动及其所反映的太阳活动规律具有重要意义．上海地区GPS综合应用网的建立，为监测长江三角洲地区电离层变化提供了宝贵的资料，利用这些双频GPS接收机的连续观测资料，可近实时地监测和预报该地区电离层总电子含量，其内外符精度和外推预报30分钟的精度均优于0.4m．  相似文献   

ANALYSIS OF SURFACE SINK OF EXPLORATION VACANCY IN GOLD MINING AREA OF ZHAOYUAN CTIY BASED ON RS AND GIS     

WU Quan-yuan AN Guo-qiang BAO Wen-dong ZHANG Zu-lu XU Qiu-xiao FANG Xue-mi 《中国地理科学(英文版)》2005,15(4):355-360

1 IN T R O D U C T IO NZhaoyuan C ity, located in northeast of ShandongProvince,iscalled "G old C ity"and itisone ofim portantgold production bases in C hina.The exploitation ofthegold broughtoutthe extensive vacantareas,leading tolarge-scale ground subsi…  相似文献   

A 2dF survey of the Small Magellanic Cloud     

Christopher J. Evans  Ian D. Howarth  Michael J. Irwin  Adam W. Burnley  Timothy J. Harries 《Monthly notices of the Royal Astronomical Society》2004,353(2):601-623

  相似文献   

Submicron polyphase inclusions in garnet from the Tananao Metamorphic Complex, Taiwan: a key to unravelling otherwise unrecognized metamorphic events     

S. L. Hwang  T. F. Yui  H. T. Chu  P. Shen 《Journal of Metamorphic Geology》2001,19(5):601-607

Kyanite and staurolite occur in the Tananao Metamorphic Complex as submicron inclusions in almandine‐rich garnet from a metamorphosed palaeosol weathering horizon, near Hoping, eastern Taiwan. Quartz, rutile/brookite and zircon are also found as associated submicron inclusions in garnet. Employing the reaction ilmenite+kyanite+quartz=almandine+rutile, and the breakdown of staurolite and quartz as thermobarometers, these submicron‐scale minerals formed at >8.3–8.8 kbar and < 660–690 °C. This P–T estimate is different from that (i.e. 5–7 kbar and 530–550 °C) derived from matrix minerals, which include almandine‐rich garnet, muscovite, chlorite, chloritoid, plagioclase, quartz and ilmenite. These results suggest that submicron inclusions in garnet‐like materials may record portions of the otherwise undocumented prograde path or provide information about previous metamorphic events and thus yield new insights into orogenic belts.  相似文献