CATASTROPHIC ECO-ENVIRONMENTAL CHANGE IN THE SONGNEN PLAIN, NORTHEASTERN CHINA SINCE 1900S   总被引：1，自引：1，他引：0  

WANGHai-xia WANZhong-juan YUShao-peng LUOXin-zheng SUNGuang-you 《中国地理科学(英文版)》2004,14(2):179-185

Although the Songnen Plain in the northeastern China was developed relatively late in the temperate zone of the world, its eco-environment has changed greatly. This paper analyzes the changes of land cover and the rates and trends ofdesertification during the past 100 years in the Songnen Plain. According to the macroscopic analysis, we find that the eco-environment in the plain has reached to the threshold of catastrophic change since the 1950s. The Thorn Needle Catastrophic Model was used to determine and validate this conclusion. Human activities, including large-scale construction projects, such as huge dams and dikes, and excessive grazing were the primary factors contributing to regional eco-environmental catastrophe. And irrational reclamation of the wilderness also affected the eco-environmental change. The results reveal the complex human-land interactions.  相似文献   

青海省沙柳河南区有色金属矿成矿物质来源及矿床成矿模式探讨     

马永铨  姜洪成 《青海国土经略》1994,(1)

本文简述了沙柳河南区有色金属矿床的基本特征。通过对成矿热液及成矿物质的来源与性质的研究,认为该矿床的成因类型为火山沉积—接触交代改造叠加型,进而探讨了该矿床的成矿模式。  相似文献   

Automatic Determination of Stellar Atmospheric Parameters Using Neural Networks and Instance-Based Machine Learning     

Olac Fuentes 《Experimental Astronomy》2001,12(1):21-31

In this article we show how machine learning methods can beeffectively applied to the problem of automatically predictingstellar atmospheric parameters from spectral information, a veryimportant problem in stellar astronomy. We apply feedforwardneural networks, Kohonen's self-organizing maps andlocally-weighted regression to predict the stellar atmosphericparameters effective temperature, surface gravity and metallicityfrom spectral indices. Our experimental results show that thethree methods are capable of predicting the parameters with verygood accuracy. Locally weighted regression gives slightly betterresults than the other methods using the original dataset asinput, while self-organizing maps outperform the other methods when significant amounts of noise are added. We also implemented a heterogeneous ensemble of predictors, combining the results given by the three algorithms. This ensemble yields better results than any of the three algorithms alone, using both the original and the noisy data.  相似文献   

淮山提取液替代羧甲基纤维素钠作为酸奶稳定剂的效果研究     

曾少葵  蒋志红  吴红棉 《广东海洋大学学报》2001,21(1):51-55

采用正交试验等方法对淮山提取液（DB-Ext）代替羧甲基纤维素钠(CMC)作为调配型酸奶稳定剂的效果进行了初步探讨。结果表明以原料的6.0倍水量在110℃的温度条件下，提取40min，所得的淮山提取液的粘度为3500mPa  相似文献   

Paleoproterozoic Extensional Structure and Its Controlling on Mineralization in the East of Liaoning Province     

Yang Zhongzhu  Chen Shuliang  Li Xiandong  Wang Zhongjiang  Qu Hongxiang  Gang Jiang 《东北亚地学研究》2001,(1)

IntroductionThe area of eastern Liaoning is an importantmetal and nonmetal metallogenetic district in China,and the Liaohe group is one of the most importantstrata that hosts Pb, Zn, Au, B and Mg etcstratabound deposits. Up to now many geo1ogistssuch as Z…  相似文献   

区域环境地球化学空间信息系统     

徐江 《地球信息科学学报》1996,(1):21-25

本文阐述了地理信息系统在环境地球化学中的应用,提出建立区域环境地球化学空间信息系统的方法、功能及组成,并以红枫湖区域环境地球化学空间信息系统为例,作了分析。  相似文献   

Accretion disk spectra of super-luminal jet sources and ultra-luminous compact X-ray sources in nearby spiral galaxies     

Ken Ebisawa  Aya Kubota  Tsunefumi Mizuno  Piotr Życki 《Astrophysics and Space Science》2001,276(1):11-14

The Ultra-luminous Compact X-ray Sources (ULXs)in nearby spiral galaxies and the Galactic super-luminaljet sources sharethe common spectral characteristic that they haveextremely high disk temperatures which cannot be explainedin the framework of the standard accretion disk modelin the Schwarzschild metric. We have calculated an extreme Kerr disk model to examine if the Kerr disk model can instead explain the observed `too hot' accretion disk spectra.We found that the Kerr disk spectrum becomes significantly hardercompared to the Schwarzschild disk only when the disk is highlyinclined.For super-luminal jet sources, which are known to beinclined systems, the Kerr disk model may thuswork if we choose proper values for the black hole angular momentum. For the ULXs, however, the Kerr disk interpretation will be problematic,as is is highly unlikely that their accretion disks are preferentiallyinclined.  相似文献   

Force-free magnetic fields on curvilinear coordinate surfaces     

Chung-Ming Ko  Ing-Guey Jiang 《Astrophysics and Space Science》1996,245(1):117-129

To seek nonlinear solutions of force-free magnetic fields, some symmetries or approximations are usually invoked. We consider magnetic fields lying on coordinate surfaces of an orthogonal curvilinear coordinate system. We conclude that only fields on parallel planes or spherical shells can be expressed in the form provided by Low in 1980s. These force-free fields are stable against small perturbations with rigid boundaries. Fields on cylindrical shells are also considered.  相似文献   

On the microwave millisecond spike emission and its associated phenomena during the impulsive phase of large solar flare     

Chun-sheng Li  Qi-jun Fu  Yu-hua Yan  Shu-ying Jiang  Hong-wei Li 《Chinese Astronomy and Astrophysics》1985,9(2):128-133

We propose a model of two acceleration regions, which can explain, on the basis of microwave maser caused by a “hollow-beam” distribution of electrons, the presence of millisecond spikes in the event of 1981 May 16 and their absence in the event of 1981 October 12, and the enhanced continuous emission in the latter. We have also uncovered relations among the features, e.g. the Type III_G, Type IV_DCIM and hard x-ray bursts, that accompany the microwave millisecond spikes during the impulsive phase of a large flare.  相似文献   

CLIMATIC　TREND　INDICATED　BY　VARIATIONS　OF　GLACIERS　AND　LAKES　IN　THE　TIANSHAN　MOUNTAINS     

胡汝骥  杨川德  马虹  姜逢清 《中国地理科学(英文版)》1996,6(3):239-246

ＣＬＩＭＡＴＩＣＴＲＥＮＤＩＮＤＩＣＡＴＥＤＢＹＶＡＲＩＡＴＩＯＮＳＯＦＧＬＡＣＩＥＲＳＡＮＤＬＡＫＥＳＩＮＴＨＥＴＩＡＮＳＨＡＮＭＯＵＮＴＡＩＮＳ￥ＨｕＲｕｊｉ；ＹａｎｇＣｈｕａｎｄｅ；ＭａＨｏｎｇ；ＪｉａｎｇＦｅｎｇｑｉｎｇ（ＸｉｎｊｉａｎｇＩｎ...  相似文献