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21.
基于1995~2010武汉城市圈城乡路网空间数据,综合运用复杂网络理论、动力系统理论及现代控制理论等多学科的方法和理论,采取随机故障和蓄意侵略两种攻击策略及多种评价指标,通过建立动力学演化模型并进行模拟仿真,揭示武汉城市圈城乡道路网的空间稳定性:(1)因分布相对均匀,节点连接随机多样,在面临随机攻击时,武汉城市圈城乡路网体现出“类随机性”,抗攻击能力强;(2)高度节点、高介数节点失效时,引致的城乡路网效率和结构变化程度不一,高介数节点失效往往更容易导致路网破碎和效率降低(形成众多子图);(3)桥梁和高速成为整个圈域城乡路网的关键边,不同桥梁或高速路段相对网络稳定性的重要程度不一样:圈域中心城区的大桥和二桥、南北向的京港澳、大广高速成为整个城乡路网的关键路径  相似文献   
22.
The assessment of regional climate change impacts combined with the sensitivity of landscape functions by predictive modelling of hazardous landscape processes is a new fundamental field of research. In particular, this study investigates the effects of changing weather extremes on meso-regional-scale landscape vulnerability. Climatic-exposure parameter analysis was performed on a predicted climate change scenario. The exposure to climate change was analysed on the basis of the original data of the meso-scale IPCC A1B climate scenario from the REMO and ALADIN regional models for the periods of 2021–2050 and 2071–2100, and the regional types of climate change impacts were calculated by using cluster analysis. Selected climate exposure parameters of the REMO and ALADIN models were analysed, in particular, for extreme events (days with precipitation greater than 30 mm, heat waves, dry periods, wet periods) and for daily temperature and precipitation. The landscape functions impacted by climate change are proxies for the main recent and future problematic processes in Hungary. Soil erosion caused by water, drought, soil erosion caused by wind, mass movement and flash floods were analysed for the time periods of 1961–1990, 2021–2050 and 2071–2100. Based on the sensitivity thresholds for the impact assessments, the landscape functional sensitivity indicators were interpreted, and an integrative summary of the five indicators was made, differentiating the regions facing only a few or multiple sensitivities. In Central Hungary, the increasing exposure and sensitivity to droughts will be a serious problem when following the REMO scenario. In several regions, most indicators will change the sensitivity threshold from a tolerable risk to an increased or very high risk.  相似文献   
23.
In intrasexual conflicts, contestants can rely on relative or absolute size of status badges to mediate aggressive behavior. Most studies focus on the response of focal animals to variation in status badges of their competitors; few have simultaneously considered the traits of both participants under experimental conditions. By simulating territorial intrusions, we tested the importance of two sexual traits [forehead patch size (FPS) and wing patch size (WPS)] in territorial behavior of males in a Hungarian population of the collared flycatcher, Ficedula albicollis. We presented a stimulus male to an unpaired resident male to examine whether the characteristics of the territory owner or those of the challenger were associated with the latency of the first attack of the owner, which is a good predictor of the territorial behavior in general. WPS of the stimulus male was a significant determinant of the latency of the first attack, as males with a larger WPS elicited quicker attacks from the residents than males with a small WPS. From the residents’ perspective, age appeared to influence their territorial behavior, as yearlings had shorter attack latencies than older males. Additionally, latency could be considered an individual-specific attribute because it varied consistently among males, even when the WPS of the stimulus male was controlled, and it was associated with pairing success. Contrary to findings in a Swedish population, FPS seemed to be unimportant in male–male competition in our population, which suggests population differences in the role of the two plumage traits. Our results indicate that in a territorial conflict, the characteristics of both participants are important.  相似文献   
24.
Xu L  Guo J  Jin F  Zeng H 《Chemosphere》2006,62(5):823-826
Adsorption of SO(2) from the O(2)-containing flue gas by granular activated carbons (GACs) and activated carbon fibers (ACFs) impregnated with NH(3) was studied in this technical note. Experimental results showed that the ACFs were high-quality adsorbents due to their unique textural properties. In the presence of moisture, the desulphurization efficiency for the ACFs was improved significantly due to the formation of sulfuric acid. After NH(3) impregnation of ACF samples, nitrogen-containing functional groups (pyridyl C(5)H(4)N- and pyrrolyl C(4)H(4)N-) were detected on the sample surface by using an X-ray photoelectron spectrometer. These functional groups accounted for the enhanced SO(2) adsorption via chemisorption and/or catalytic oxidization.  相似文献   
25.
Social parasites exploit the socially managed resources of social insect colonies in order to maximise their own fitness. The inquilines are among the most specialised social parasites, because they are dependent on being fully integrated into their host's colony throughout their lives. They are usually relatives of their host and so share ancestral characteristics (Emery's rule). Closely related inquiline-host combinations offer a rare opportunity to study trade-offs in natural selection. This is because ancestral adaptations to a free-living state (e.g. the production of a worker caste) become redundant and may be replaced by novel, parasitic traits as the inquiline becomes more specialised. The dynamics of such processes are, however, unknown as virtually all extant inquiline social parasites have completely lost their worker caste. An exception is Acromyrmex insinuator, an incipient permanent social parasite of the leaf-cutting ant Acromyrmex echinatior. In the present study, we document the size distribution of parasite and host workers and infer how selection has acted on A. insinuator to reduce, but not eliminate, its investment in a worker caste. We show that the antibiotic producing metapleural glands of these parasite workers are significantly smaller than in their host counterparts and we deduce that the metapleural gland size in the host represents the ancestral state. We further show experimentally that social parasite workers are more vulnerable to the general insect pathogenic fungus Metarhizium than are host workers. Our findings suggest that costly disease resistance mechanisms are likely to have been lost early in inquiline evolution, possibly because active selection for maintaining these traits became less when parasite workers had evolved the ability to exploit the collective immune system of their host societies.  相似文献   
26.
重庆主城区建设用地扩展的时空特征及驱动因子分析   总被引:1,自引:0,他引:1  
以多时相的遥感影像为基础,选用归一化裸露指数(NDBI)、重归一植被指数(RDVI)和改进的归一化水体指数(修改后的NDWI),通过阈值分割、掩膜处理提取建设用地信息,结合重庆主城区的社会经济数据,利用扩展速度指数、扩展强度指数、扩展弹性指数、紧凑度指数、建设用地扩展系数及扩展方向分析研究了不同阶段建设用地扩展的时空动态特征,并运用灰色关联分析,对建设用地扩展的驱动因子进行探讨。结果表明:1988~2011年重庆主城区建设用地扩展了39332 km2,扩展速度和扩展强度呈现增大的趋势;扩展弹性系数、建设用地扩展系数波动变化,反映了重庆主城区建设用地逐渐由粗放型向集约型转变;建设用地扩展的空间分析表明重庆主城区的城市形态由非紧凑型向紧凑型发展,同时扩展方向具有明显的分异性,主要向正北和西北方向扩展;人口增长,尤其是城市人口的增长是重庆主城区建设用地扩展最主要的驱动因子;经济发展、产业结构变化与建设用地的扩展也有明显的相关性  相似文献   
27.
水资源问题是我国面临的重要资源与环境问题。流域水资源配置的有效性缺失也使水资源问题进一步恶化,而水资源配置过程中大量不确定信息也使高效决策问题更加困难。基于区间直觉模糊群决策的水资源配置方案优化方法,分析了水资源系统作为复杂系统的特殊性和区间直觉模糊理论在群决策中应用的优势,利用区间模糊数来表达专家判断信息,提高了流域水资源配置方案的合理性。通过多个水资源领域专家的群体决策,从流域水资源可持续利用评价视角出发,针对流域的社会、经济、资源、环境等多个因素进行判断,利用IIWAA算子进行群体意见集成,最后根据流域指标与理想点逼近点的距离对流域水资源配置方案排序。通过赣抚平原灌区内的用水区域在不同方案情景下的水资源可持续利用实例分析表明,该方法能够比较准确地评估出流域水资源配置方案的可持续性,为流域的水资源配置方案制定提供有效合理的决策支持  相似文献   
28.
利用鄱阳湖流域16个气象站1960~2008年共49 a的月降雨资料,采用Morlet小波函数,对该流域降雨季节变化、年际和年代际时间序列进行小波分析,揭示了流域降雨变化的多时间尺度特征,分析了不同时间尺度下降雨序列变化的周期和突变点。研究表明:①1960~1990年,年降雨量呈明显年际和代际振荡,并无显著趋势;进入90年代以后,年降雨呈现显著上升趋势;进入21世纪,尤其从2002年开始,年降雨量开始减少;②流域季节降雨和年降雨都存在多时间尺度特征,夏季降雨、冬季降雨和年降雨都存在18 a的第一主周期;春季、冬季和年降雨存在6 a次主周期;此外,春季、秋季、冬季和年降雨均存在3 a次主周期;③夏季降雨在18 a时间尺度上与年降雨变化具有相同的趋势和相位,春季降雨在3 a和6 a时间尺度上与年降雨变化具有相似趋势和相位变化  相似文献   
29.
随着“十八大”报告中全面建成小康社会目标的提出,我国的社会经济发展将进一步加快,生态环境所承受的压力势必也将增大,如何协调城市发展与城市的生态安全已经成为一个不可回避的问题。我国是一个多山的国家,山地、丘陵及高原面积占国土面积的69%,山区生态系统脆弱,自然灾害频发,水土流失严重,极大的制约了其社会经济的发展,因此以巫山为例,在世界经合组织建立的PSR模型框架下,将熵值赋权法与灰色系统理论相结合,通过分析巫山县各指标2001~2011年统计数据,用熵值法赋予权重值,计算各指标灰色关联度,得到了其生态安全状态,并对巫山县生态安全等级状况进行了动态评价。巫山县生态安全综合指数由2001年的0.59(Ⅲ级)发展到2011年的0.66(Ⅳ级),个别年份有些许波动,整体生态安全状况呈现良好的发展态势,生态环境压力有所缓解。生态安全综合指数及各分项指数较高,巫山县生态环境处于较好状态  相似文献   
30.
Detection of soil element deficiencies is time consuming, requiring a major commitment for field work and analysis. Bees concentrate some elements in their honey which could allow soil element concentrations to be predicted without having to take large numbers of soil samples. We measured 14 element concentrations in soil, sunflower, acacia flower and honey samples from two different regions of Hungary. Across sites, the elements with significant correlation coefficients between honey and soil concentrations, in descending order of probability, were Cu > Ba >Sr = Ni > Zn > Mn = Pb >As. Bioconcentration from soil to honey was similar for areas with acacia and sunflower flowers. In the macroelements, it was the greatest for K, S and P and least for Mg and Na, and in the microelements, greatest for B, then Zn, then Cu, then As, Mo and Sr and least for Fe, Ba, Mn and Pb. It is concluded that in acacia and sunflower-growing regions, honey can give an accurate estimate of soil element concentrations for Cu and Ba and provides relevant information for Sr, Ni, Zn, Mn, Pb and As.  相似文献   
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