选取北京、上海、广州、武汉和重庆5个点作为高铁经济区的基准点,以国家铁路和高速公路规划为基础数据库,根据二维扭曲时空地图的制作原理,运用GIS软件和Visual Studio 2008程序编辑平台,制定基于高铁的"中国多中心地图",模...选取北京、上海、广州、武汉和重庆5个点作为高铁经济区的基准点,以国家铁路和高速公路规划为基础数据库,根据二维扭曲时空地图的制作原理,运用GIS软件和Visual Studio 2008程序编辑平台,制定基于高铁的"中国多中心地图",模拟各高铁经济区内城市通达基准点的时间。分析发现:①高铁建成后,全国5大高铁经济区节省的时间约占原通达时间的34%,不同节点节省时间的差异较大。其中2h经济圈范围内,高铁沿线城市的通达时间节约比例高达50%;2h经济圈以外该比例则集中在30%～40%之间;距离基准点越远,高铁对时间成本节约的价值相对越低。②高铁建成后,全国总体上空间极化现象显著,板块化特征显现,而线性特征明显弱化。如,京津冀和济南都市圈形成一体化区域,以沈阳都市圈为中心形成东北城镇密集区,以武汉都市圈为中心容纳中原城市群和皖江城市群部分地区的长江中游城镇密集区,长三角城市群扩展到了海西经济区,泛珠三角城市群涵盖了北部湾经济区。北京—哈尔滨、西安—乌鲁木齐和重庆—贵阳—南宁成为中国3大重要的线性城镇走廊。③各高铁经济区空间组织模式的分异特征显著。上海和广州高铁经济区可归纳为向心式模式,武汉和北京高铁经济区为圈层式结构,而重庆高铁经济区则属于典型的空心式模式。展开更多
We propose a cryptographic scheme based on spatiotemporal chaos of coupled map lattices （CIVIL） ,which is based on one-time pad. The structure of the cryptosystem determines that the progress in decryption implies t...We propose a cryptographic scheme based on spatiotemporal chaos of coupled map lattices （CIVIL） ,which is based on one-time pad. The structure of the cryptosystem determines that the progress in decryption implies the progress in exploring the dynamical behavior of spatiotemporal chaos in CML. A part of the initial condition of CML is used as a secret key, and the recovery of the secret key by exhaustive search is impossible due to the sensitivity to the initial condition in spatiotemporal chaos system. Specially the software implementation of the scheme is easy.展开更多
The objective of this study was to provide reliable basis for decision making for national food security and layout and structure adjustment of grain production in the northeastern China. The data of mean daily air te...The objective of this study was to provide reliable basis for decision making for national food security and layout and structure adjustment of grain production in the northeastern China. The data of mean daily air temperature of 1961-2009 from 106 meteorological stations in the northeastern China were chosen in this study. Using statistical methods and isoline method, the spatio-temporal changes of various decadal ≥10℃accumulated temperature and the climatic means of ≥10℃ accumulated temperature were studied in this paper. The results showed that 1） The geo- graphical distribution of ≥10℃ accumulated temperature in the northeastern China could be influenced directly by the latitude, longitude and altitude. If latitude moved one degree northward, the average decrease amplitude of the climatic means was 101.9℃ in the study area. 2） The means of decadal ≥10℃ accumulated temperature rose since the 1980s, and their increase amplitudes became larger in the 1990s and the 2010s obviously. Compared with those of the 1980s, ≥10℃ accumulated temperature increased by about 100℃ in the mountainous and plain areas in the 1990s; compared with those of the 1990s, ≥10℃ accumulated temperature increased by about 200℃ in the Hulun Buir High Plain and the Songnen Plain, and 100℃ in the Sanjiang Plain and the Liaohe Plain in the 2010s. 3） The means of the decada ≥10℃accumulated temperature for 106 meteorological stations in the northeastern China increased with the rate of 145.57℃/10yr in 1961-2009.4） The climatic means of ≥10℃ accumulated temperature increased from 1961-1990 to 1971-2000 and 1981-2009. Compared with the climatic mean of 1971-2000, that of 1981-2009 had increased by above 50℃ in most of the study area, even up to 156℃. Compared with the climatic mean of 1961-1990, that of 1981-2009 increased by above 100℃ in most parts of the study area, even up to 200℃. 5） The maximum northward shift, eastward and westward extension amplitudes of3100℃, 3300℃ and 3500℃ isolines were larger among all isolines for the climatic means of the three phases. Compared with the positions of the isolines of 1961-1990, those amplitudes of 31000C isoline of 1981-2009 were 145 km, 109 km and 64 km, respectively; those of 3300℃ isoline were 154 km, 54 km and 64 km, respectively; and the maximum northward shift of 3500℃ isoline was about 100 km.展开更多
文摘选取北京、上海、广州、武汉和重庆5个点作为高铁经济区的基准点,以国家铁路和高速公路规划为基础数据库,根据二维扭曲时空地图的制作原理,运用GIS软件和Visual Studio 2008程序编辑平台,制定基于高铁的"中国多中心地图",模拟各高铁经济区内城市通达基准点的时间。分析发现:①高铁建成后,全国5大高铁经济区节省的时间约占原通达时间的34%,不同节点节省时间的差异较大。其中2h经济圈范围内,高铁沿线城市的通达时间节约比例高达50%;2h经济圈以外该比例则集中在30%～40%之间;距离基准点越远,高铁对时间成本节约的价值相对越低。②高铁建成后,全国总体上空间极化现象显著,板块化特征显现,而线性特征明显弱化。如,京津冀和济南都市圈形成一体化区域,以沈阳都市圈为中心形成东北城镇密集区,以武汉都市圈为中心容纳中原城市群和皖江城市群部分地区的长江中游城镇密集区,长三角城市群扩展到了海西经济区,泛珠三角城市群涵盖了北部湾经济区。北京—哈尔滨、西安—乌鲁木齐和重庆—贵阳—南宁成为中国3大重要的线性城镇走廊。③各高铁经济区空间组织模式的分异特征显著。上海和广州高铁经济区可归纳为向心式模式,武汉和北京高铁经济区为圈层式结构,而重庆高铁经济区则属于典型的空心式模式。
基金The project supported by National Natural Science Foundation of China under Grant No. 90203008 and the Doctoral Foundation of the Ministry of Education of China under Grant No. 2002055009
文摘We propose a cryptographic scheme based on spatiotemporal chaos of coupled map lattices （CIVIL） ,which is based on one-time pad. The structure of the cryptosystem determines that the progress in decryption implies the progress in exploring the dynamical behavior of spatiotemporal chaos in CML. A part of the initial condition of CML is used as a secret key, and the recovery of the secret key by exhaustive search is impossible due to the sensitivity to the initial condition in spatiotemporal chaos system. Specially the software implementation of the scheme is easy.
基金Under the auspices of National Natural Science Foundation of China (No. 40771190)Special Fund for Meteorological Scientific Research in the Public Interest (No. GYHY200706030)
文摘The objective of this study was to provide reliable basis for decision making for national food security and layout and structure adjustment of grain production in the northeastern China. The data of mean daily air temperature of 1961-2009 from 106 meteorological stations in the northeastern China were chosen in this study. Using statistical methods and isoline method, the spatio-temporal changes of various decadal ≥10℃accumulated temperature and the climatic means of ≥10℃ accumulated temperature were studied in this paper. The results showed that 1） The geo- graphical distribution of ≥10℃ accumulated temperature in the northeastern China could be influenced directly by the latitude, longitude and altitude. If latitude moved one degree northward, the average decrease amplitude of the climatic means was 101.9℃ in the study area. 2） The means of decadal ≥10℃ accumulated temperature rose since the 1980s, and their increase amplitudes became larger in the 1990s and the 2010s obviously. Compared with those of the 1980s, ≥10℃ accumulated temperature increased by about 100℃ in the mountainous and plain areas in the 1990s; compared with those of the 1990s, ≥10℃ accumulated temperature increased by about 200℃ in the Hulun Buir High Plain and the Songnen Plain, and 100℃ in the Sanjiang Plain and the Liaohe Plain in the 2010s. 3） The means of the decada ≥10℃accumulated temperature for 106 meteorological stations in the northeastern China increased with the rate of 145.57℃/10yr in 1961-2009.4） The climatic means of ≥10℃ accumulated temperature increased from 1961-1990 to 1971-2000 and 1981-2009. Compared with the climatic mean of 1971-2000, that of 1981-2009 had increased by above 50℃ in most of the study area, even up to 156℃. Compared with the climatic mean of 1961-1990, that of 1981-2009 increased by above 100℃ in most parts of the study area, even up to 200℃. 5） The maximum northward shift, eastward and westward extension amplitudes of3100℃, 3300℃ and 3500℃ isolines were larger among all isolines for the climatic means of the three phases. Compared with the positions of the isolines of 1961-1990, those amplitudes of 31000C isoline of 1981-2009 were 145 km, 109 km and 64 km, respectively; those of 3300℃ isoline were 154 km, 54 km and 64 km, respectively; and the maximum northward shift of 3500℃ isoline was about 100 km.
