DISASTER ANALYSIS AND COUNTERMEASURES OF LAND SUBSIDENCE CAUSED BY COAL CUTTING IN CHINA     

YANGYong-liang SHITong-guang JLANGLU-guang LIYue 《中国地理科学(英文版)》2003,13(2):130-133

In recent years, many coal-producing countries have paid great attention to the land subsidence causedby coal cutting. In China, because of the dense population in coalfield areas, the land subsidence hazard is more seri-ous. After a brief analysis on the mechanism of land subsidence, this paper gives a comprehensive and systematical ac-count on all kinds of hazards caused by the land subsidence in China. The study shows that land subsidence has endan-gered land, buildings, traffic and communication lines, dykes and dams. It also causes damage to ecological and socialenvironment. In order to lessen the hazard of land subsidence, preventive measures should be taken to reduce the col-lapse amount, such as extraction with stowing, banded mining system, succession and coordination mining system, orhigh-pressure mudflow between rock strata. Measures of reinforcing or moving certain buildings should also be taken toreduce the destructive degree. In order to harness the subsidence land and bring them under control for fanning, mea-sures should be taken such as filling with spoil or fine breeze, excavating the deeper and covering the shallower land.  相似文献   

Multistep matched-field inversion for broad-band data from ASIAEX2001     

Kunde Yang Yuanliang Ma Chao Sun Miller  J.H. Potty  G.R. 《Oceanic Engineering, IEEE Journal of》2004,29(4):964-972

This paper discusses the results of geoacoustic inversion carried out using explosive charge data from the Asian Seas International Acoustic Experiment (ASIAEX) East China Sea (ECS) Experiment. A multifrequency incoherent matched-field inversion processor and a genetic algorithm (GA) are used for the inversion. A multistep matched field inversion approach is presented, which makes use of the varying sensitivities of wave fields at various frequencies to reduce the inversion problem into a sequence of smaller inversions with fewer unknowns to estimate at each stage. Different parameters are estimated using data at different frequencies according to their sensitivities. Inversion results for different areas in the ECS region are summarized and compared with core data.  相似文献   

SORPTION AND DESORPTION CHARACTERISTICS OF CADMIUM BY FOUR DIFFERENT SOILS IN NORTHEAST CHINA   总被引：3，自引：0，他引：3  

ZHANG Lei SONG Feng-bin 《中国地理科学(英文版)》2005,15(4):343-347

1IN TR O D U C TIO NA s a persistentand toxic pollutant, cadm ium (C d) canresultin m any adverse health effects in a variety oftis-suesand organssuch asthe lung,kidney,urinary,blad-der,pancreas,breast and prostate (SA TA R U G etal.,2003).C adm ium in so…  相似文献   

Seasonal and annual variation of CO2 flux above a broad-leaved Korean pine mixed forest     

Zhang  Junhui  Yu  Guirui  Han  Shijie  Guan  Dexin  Sun  Xiaomin 《中国科学:地球科学(英文版)》2006,49(2):63-73

Long-term measurement of carbon metabolism of old-growth forests is critical to predict their behaviors and to reduce the uncertainties of carbon accounting under changing climate. Eddy covariance technology was applied to investigate the long-term carbon exchange over a 200 year-old Chinese broad-leaved Korean pine mixed forest in the Changbai Mountains (128°28′E and 42°24′N, Jilin Province, P. R. China) since August 2002. On the data obtained with open-path eddy covariance system and CO₂ profile measurement system from Jan. 2003 to Dec. 2004, this paper reports (i) annual and seasonal variation of F _NEE, F _GPP and R _E; (ii) regulation of environmental factors on phase and amplitude of ecosystem CO₂ uptake and release Corrections due to storage and friction velocity were applied to the eddy carbon flux.

L_AI and soil temperature determined the seasonal and annual dynamics of F_GPP and R_E separately. V_PD and air temperature regulated ecosystem photosynthesis at finer scales in growing seasons. Water condition at the root zone exerted a significant influence on ecosystem maintenance carbon metabolism of this forest in winter.

The forest was a net sink of atmospheric CO₂ and sequestered −449 g C·m⁻² during the study period; −278 and −171 gC·m⁻² for 2003 and 2004 respectively. F _GPP and F _RE over 2003 and 2004 were −1332, −1294 g C·m⁻². and 1054, 1124 g C·m⁻² respectively. This study shows that old-growth forest can be a strong net carbon sink of atmospheric CO₂.

There was significant seasonal and annual variation in carbon metabolism. In winter, there was weak photosynthesis while the ecosystem emitted CO₂. Carbon exchanges were active in spring and fall but contributed little to carbon sequestration on an annual scale. The summer is the most significant season as far as ecosystem carbon balance is concerned. The 90 days of summer contributed 66.9, 68.9% of F _GPP, and 60.4, 62.1% of R _E of the entire year.

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广西小平阳岩溶区地裂缝形成因素分析     

张骏  卢玉东  孙建中  范文 《地球科学与环境学报》1996,(4)

８０年代以来，广西小平阳岩溶区出现了大量的地裂缝。通过调查研究．这些地裂缝的形成是受多种因素控制的．其中包括构造、土体性质、水的作用、地形地貌、气候及植被等因素。在上述因素中．构造是主导因素，上体性质是基础因素．其它则为诱发因素，也是因地质环境要素变化所引起的因素。主导因素是通过诱发因素起作用的．并最终通过土体性质因素导致产土地裂缝。  相似文献   

Tidal effects on temperature front in the Yellow Sea   总被引：5，自引：0，他引：5  

Ma Jian  Qiao Fangli  Xia Changshui  Yang Yongzeng 《中国海洋湖沼学报》2004,22(3):314-321

Temperature front (TF) is one of the important features in the Yellow Sea, which forms in spring, thrives in summer, and fades in autumn as thermocline declines. TF intensity ⋎S _T ⋎ is defined to describe the distribution of TF. Based on the MASNUM wave-tide-circulation coupled model, temperature distribution in the Yellow Sea was simulated with and without tidal effects. Along 36°N, distribution of TF from the simulated results are compared with the observations, and a quantitative analysis is introduced to evaluate the tidal effects on the forming and maintaining processes of the TF. Tidal mixing and the circulation structure adapting to it are the main causes of the TF. Supported by the National Basic Research Program of China (No. G1999043809) and the National Science Foundation of China (No. 49736190).  相似文献   

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   

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   

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   

Prediction in Real Time of the 2000 July 14 Heliospheric Shock Wave and its Companions During the `Bastille' Epoch*     

Dryer  M.  Fry  C.D.  Sun  W.  Deehr  C.  Smith  Z.  Akasofu  S.-I.  Andrews  M.D. 《Solar physics》2001,204(1-2):265-284

Prediction of solar-generated disturbances and their three-dimensional propagation through interplanetary space continues to present a vitally important operational space weather forecasting objective. This paper presents the first successful real-time prediction of a series of major heliospheric shock waves at Earth, including the one from the 14 July 2000 (`Bastille Day') flare. An ensemble of three models and their predictions were distributed to a world-wide group of interested scientists as part of an informal Internet space weather forecast research program. Two of the models, STOA (Shock Time of Arrival) and ISPM (Interplanetary Shock Propagation Model), presently in operation by the US Air Force Weather Agency, provided predictions of shock arrival time (SAT) that were, respectively, 0.5 hours after and 3.7 hours before the observed arrival. The third model, HAFv.2 (Hakamada–Akasofu–Fry version 2.0) predicted a time 0.3 hours after the observed shock arrival time (14:37 UT, 15 July 2000). Of primary interest to this study is the third model, firstly in terms of its capability of propagating shocks through non-uniform solar wind conditions, and secondly, in terms of its ability to integrate multiple solar events and display them graphically along with the background solar wind. This latter capability was brought to bear on ten real-time-reported flares, some with CMEs (coronal mass ejections) that took place as companions to the Bastille flare during the period 7–15 July 2000. Some limited statistics are given regarding the three models' shock arrival prediction capability at Earth, as an extension of our earlier studies with this three model ensemble in the prediction of SAT. HAFv.2, however, was able to describe not only the ten events and their interaction as measured at Earth, but also at the spacecraft NEAR (orbiting the asteroid, Eros, at 1.8 AU), and CASSINI (en route, at 4.0 AU, to Saturn). Several important points are noted: (1) this epoch represents a small statistical sample that should be expanded; and (2) the three models, based on theory, empiricism, and simulations represent the state of the art that should presage a similar community process. This paper was presented earlier as an Invited Talk at the American Geophysical Union Fall Meeting, December 14–19, 2000, in San Francisco, CA, U.S.A.toward space weather objectives in the Sun-Earth domain. Supplementary material to this paper is available in electronic form at http://dx.doi.org/10.1023/A:1014200719867  相似文献