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921.
D.G. StavrakoudisJ.B. Theocharis G.C. Zalidis 《ISPRS Journal of Photogrammetry and Remote Sensing》2011,66(4):529-544
A Boosted Genetic Fuzzy Classifier (BGFC) is proposed in this paper, for land cover classification from multispectral images. The model comprises a set of fuzzy classification rules, which resemble the reasoning employed by humans. Fuzzy rules are generated in an iterative fashion, incrementally covering subspaces of the feature space, as directed by a boosting algorithm. Each rule is able to select the required features, further improving the interpretability of the obtained model. After the rule generation stage, a genetic tuning stage is employed, aiming at improving the cooperation among the fuzzy rules, thus increasing the classification performance attained after the first stage. The BGFC is tested using an IKONOS multispectral VHR image, in a lake-wetland ecosystem of international importance. For effective classification, we consider advanced feature sets, containing spectral and textural feature types. Comparative results with well-known classifiers, commonly employed in remote sensing tasks, indicate that the proposed system is able to handle multi-dimensional feature spaces more efficiently, effectively exploiting information from different feature sources. 相似文献
922.
针对在平面坐标转换时选取不同模型将得到不同的转换精度,通过所编程序进行实验,对比了四参数模型、六参数模型和二次曲面模型的转换精度.实验表明,当合理选择转换点时二次曲面模型在平面坐标转换中精度高于四参数模型和六参数模型的转换精度. 相似文献
923.
地理信息系统(GIS)是旅游学研究的重要技术手段,很多高校旅游管理专业已经引入地理信息系统。但相对来说,旅游管理专业本科GIS课程教育尚未受到足够的重视,根据已有研究和教学经验,结合专业特点,提出了构建旅游管理专业GIS课程教学体系的原则,并对其教学内容进行分析和探讨,以期为旅游管理专业GIS课程的建设提供借鉴和参考。 相似文献
924.
主要研究一类具有不确定项和外部扰动的离散时滞系统的鲁棒自适应控制,假设扰动和不确定项是有界的,而扰动和关于状态的不确定项的边界是不必知道的.设计了自适应控制器以保证系统能在有限时间内到达切换面,并且收敛到包含原点的一定的有界区域内.仿真的结果说明了该方法的有效性. 相似文献
925.
David Ayala-CabreraManuel Herrera Joaquín IzquierdoRafael Pérez-García 《Journal of Applied Geophysics》2011,75(4):679-686
This work focuses on the generation of tools to aid inspection and identify buried plastic pipes in water supply systems (WSS). In our study we use ground penetrating system (GPR) images as a non-destructive method of obtaining information without altering the system conditions and the environmental characteristics. A viability study for extracting features, and an approach to the above-mentioned application based on multi-agent systems are addressed in this paper. Firstly, we use intensive matrix manipulation of the GPR output for preprocessing the images. As a result, two matrices are produced that classify initial data based on the original radargram of the wave amplitude parameter. Then the plastic pipe characteristics that offer an enhanced likelihood of location are defined. This procedure is evaluated through two case-studies. One study corresponds to a simple case (one pipe) and the other corresponds to various pipes (made of different materials). Both cases were developed under controlled laboratory conditions. The obtained results are promising, and we show that automatic plastic pipe location has been achieved. The main contributions of the procedures proposed in this work are: firstly, highly skilled GPR prospection operators become unnecessary for plastic pipe location using GPR images; and secondly, we have opened a route to further classification that makes use of other methodologies. 相似文献
926.
The variance of collapse capacity is an important constituent of probabilistic methodologies used to evaluate the probability of collapse of structures subjected to earthquake ground motions. This study evaluates the effect of ground motion randomness (i.e. record‐to‐record (RTR) variability) and uncertainty in the deterioration parameters of single‐degree‐of‐freedom (SDOF) systems on the variance of collapse capacity. Collapse capacity is evaluated in terms of a relative intensity defined as the ratio of ground motion intensity to a structure strength parameter. The effect of RTR variability on the variance of collapse capacity is directly obtained by performing dynamic analyses of deteriorating hysteretic models for a set of representative ground motions. The first‐order second‐moment (FOSM) method is used to quantify the effect of deterioration parameter uncertainty. In addition to RTR variability, the results indicate that uncertainty in the displacement at the peak (cap) strength and the post‐capping stiffness significantly contribute to the variance of collapse capacity. If large dispersion of these parameters exists, the effect of uncertainty in deterioration parameters on the variance of collapse capacity may be comparable to that caused by RTR variability. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
927.
928.
外源一氧化氮和金属铜对海洋微藻抗氧化系统的影响 总被引:1,自引:0,他引:1
以亚心形扁藻为研究对象,通过添加不同浓度一氧化氮(NO)(1.4×10-10~1.4×10-5 mol/L)培养,探讨NO对微藻生长、H2O2和MDA含量以及SOD活性的影响;通过对只添加金属Cu、同时添加Cu与NO实验,对微藻的H2O2和MDA含量以及SOD活性的影响进行了对比研究。结果表明,藻细胞活性氧的代谢有随NO浓度增加的趋势,同时细胞内的抗氧化酶SOD活性和MDA含量都有相应的变化,NO作为环境的"刺激物"提高了细胞内的活性氧水平,对抗氧化系统起到激活或伤害作用。在Cu胁迫下,藻细胞活性氧代谢明显提高,SOD活性提高,并导致细胞膜脂过氧化;但外源NO能明显降低活性氧的水平,并恢复SOD活性和MDA含量,对抗氧化系统起到保护作用,提高微藻的抗氧化能力。研究表明,NO在海洋浮游植物中扮演着"双重角色"——氧化剂和抗氧化剂,从而对微藻的生长起到重要的调节作用。 相似文献
929.
Co-production between scientific and Indigenous knowledge has been identified as useful to generating adaptation pathways with Indigenous peoples, who are attached to their traditional lands and thus highly exposed to the impacts of climate change. However, ignoring the complex and contested histories of nation-state colonisation can result in naïve adaptation plans that increase vulnerability. Here, through a case study in central Australia, we investigate the conditions under which co-production between scientific and Indigenous knowledge can support climate change adaptation pathways among place-attached Indigenous communities. A research team including scientists, Ltyentye Apurte Rangers and other staff from the Central Land Council first undertook activities to co-produce climate change presentations in the local Arrernte language; enable community members to identify potential adaptation actions; and implement one action, erosion control. Second, we reflected on the outcomes of these activities in order to unpack deeper influences. Applying the theory of articulation complexes, we show how ideologies, institutions and economies have linked Indigenous societies and the establishing Australian nation-state since colonisation. The sequence of complexes characterised as frontier, mission, pastoral, land-rights, community-development and re-centralisation, which is current, have both enabled and constrained adaptation options. We found knowledge co-production generates adaptation pathways when: (1) effective methods for knowledge co-production are used, based on deeply respectful partnerships, cultural governance and working together through five co-production tasks—prepare, communicate, discuss, bring together and apply; (2) Indigenous people have ongoing connection to their traditional territories to maintain their Indigenous knowledge; (3) the relationship between the Indigenous people and the nation-state empowers local decision-making and learning, which requires and creates consent, trust, accountability, reciprocity, and resurgence of Indigenous culture, knowledge and practices. These conditions foster the emergence of articulation complexes that enable the necessary transformative change from the colonial legacies. Both these conditions and our approach are likely to be relevant for place-attached Indigenous peoples across the globe in generating climate adaptation pathways. 相似文献
930.
随着人工智能以及通信技术的发展,减少通信资源及计算资源的浪费,延长宽带和硬件的使用寿命成为了一个关键的问题.事件触发控制,即当某一变量超过给定阈值时,系统才进行采样,控制器才进行更新,有效地节约了线上通信及计算资源.本文首先分析了连续时间和离散时间下的事件触发控制,讨论了自触发控制、基于边的事件触发控制、动态事件触发控制以及异步事件触发控制的主要思想.其次,分别从一致性、优化以及博弈方面阐述了事件触发的广泛应用.同时,给出了两种常见的稳定性分析方法和两种排除系统中可能存在的Zeno行为的论证方法.最后对本文进行了总结,指出了当前事件触发工作的不足之处并对未来的研究做出展望. 相似文献