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51.
ZHANGXue-qin GEQuan-sheng ZHENGJing-yun 《中国地理科学(英文版)》2003,13(3):207-215
How land-cover has been changed by human use over the last 300 years is one of the five overarching questions guiding the Land-use/Cover Change (LUCC) Science/Research Plan. China has variety of historical docu-ments providing unique data superiority. So the characteristics of farmland area in Shandong Province during the Qing Dynasty (1644-1911) are summarized firstly: 1) the rising trend of farmland area was striking; 2) farmland area had re-markable fluctuation; 3) farmland area per capita decreased dramatically; 4) wasteland reclamation index increased rapidly. Then, the driving forces of farmland area change are analyzed. It is concluded that natural and human factors are jointly influential. Among the driving forces, human dimensions are the main factors of farmland area change,which direct the general tendency of the changes mentioned above. And the natural factors influence the stability of farmland area as well. Variation of the natural factors would act as the major contributory factor to farmland area change during years or periods of abrupt climatic changes, or during the intensive occurring periods of natural hazards.Besides, the passive aspects of human factors, such as war chaos also influenced the fluctuation of the farmland area.This research indicates that it is feasible to study the land-use/cover change by Chinese historical literatures, which has huge potential to provide a comprehensive picture of the growing dominance of human land-use and land-cover pat-terns that can be used in many global change research oroiects. 相似文献
52.
WANGXie-kang HUANGEr CUIPeng 《中国地理科学(英文版)》2003,13(3):262-266
Debris flow is one of the most destructive phenomena of natural hazards. Recently, major natural haz-ard, claiming human lives and assets, is due to debris flow in the world. Several practical methods for forecasting de-bris flow have been proposed, however, the accuracy of these methods is not high enough for practical use because of the stochastic and non-linear characteristics of debris flow. Artificial neural network has proven to be feasible and use-fill in developing models for nonlinear systems. On the other hand, predicting the future behavior based on a time se-ries of collected historical data is also an important tool in many scientific applications. In this study we present a three-layer feed-forward neural network model to forecast surge of debris flow according to the time series data collect-ed in the Jiangjia Ravine, situated in north part of Yunnan Province of China. The simulation and prediction of debris flow using the proposed approach shows this model is feasible, however, further studies are needed. 相似文献
53.
小波分析理论在GPS技术中的应用 总被引:6,自引:0,他引:6
在GPS数据处理中,存在着误差影响、影响波的干扰、周跳和数据量大等问题。误差影响和影响波的干扰实质是在接收卫星信号时受到其它因素的影响;周跳是由于卫星信号的失锁而造成信号的不连续;数据量大是因为GPS观测需要采样间隔小又连续观测所致。由于小波理论具有时频分析、波形分解、特征提取和快速小波变换等特性,应用小波变换和波形分解可以解决误差影响和影响波的干扰的问题;应用特征提取可以解决周跳检测问题;应用快速小波变换可进行数据压缩。 相似文献
54.
近几年,在国土资源管理部门征收国有土地租赁租金(俗称年租金)过程中,有不少地市同房管部门征收的出租门面房土地收益金“撞车”,它不仅造成同一种费用重复征收,加重用地单位的负担,损害政府形象,而且形成多头管理土地,使土地资产大量流失,甚至导致不安定因素的发生。造成此种现象的主要原因,虽然是某些部门的职能越位和错位,但是概念混淆、政策打架也是其原因之一。因此,要解决此问题,首先要弄清“土地收益金”和“土地收益”二者的概念。 让我们来看一下房管部门征收“土地收益金”的主要依据,它是根据建设部(1995)第42号令《城市房屋… 相似文献
55.
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
56.
疏散星团在天文学和天体物理学研究中有着多方面的重要性。近年来在观测和理论工作上都取得了显著的进展。综述了疏散星团的研究现状,对成员判别、基本参数确定、团与恒星的演化、团的结构和动力学进行了详细评述。 相似文献
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59.
经省政府同意.河南省整顿和规范矿产资源开发秩序领导小组日前下发了《河南省全面整顿和规范矿产资源开发秩序实施方案》(以下简称《实施方案》),结合我省实际,对全省矿产资源开发秩序的整顿和规范工作进行了安排部署,以解决当前矿产资源开发中存在的突出问题。 相似文献
60.
世界各国的发展都必须面对的是这样一个共同性的基本问题,即人类社会对物质产品数量、性能、品种追求的无限性与自然环境、物质生产及供给能力的有限性之间的矛盾。人类自出现以来就开始努力从自然界中谋求生存并争取更好的生存(发展的本质就在于此),这种努力永不停歇。尽管人类社会追求物质产品的无限性和自然环境供给能力的有限性是客观存在的,但人类认识到他们的存在,特别是认识到这二者之间矛盾的严重性和普遍性,却有一个相当漫长的过程。 相似文献