基于蚁群算法的城市可持续发展综合评价   总被引：1，自引：0，他引：1  

徐婷婷  于扬  彭娇婷 《成都信息工程学院学报》2006,21(5):694-697

在可持续发展体系分类的基础上，应用蚁群算法对可持续发展各分类指数公式和综合指数公式进行优化，建立可持续发展评价模型。将该模型应用于乌鲁木齐市可持续发展水平评价，评价结果与现状分析一敛。结果表明该模型简单适用、有良好的通用性。  相似文献   

The Roche Limit     

I. P. Williams 《Celestial Mechanics and Dynamical Astronomy》2003,87(1-2):13-25

The role of tides in deforming and possibly disrupting a secondary body orbiting about a primary body has been known for a considerable time. This was first inspired by the observations of ocean tides on Earth and then seen as playing an important role in the formation and evolution of the Earth–Moon system. Finally, in the beginning of the 20th century it was generally thought to have a significant role in the formation of the solar system through the tidal disruption of the Sun. Here, an overview of the historical developments of the ideas concerned with tidal disruption of a secondary body that can lead to mass loss is given. Some discussion of possible extensions to consider more realistic situations where the secondary body may not be moving on a circular orbit and may not rotate so as to maintain the phase-on configuration to the primary body is also given.  相似文献   

东海虾类的生态群落与区系特征   总被引：6，自引：0，他引：6  

宋海棠 《海洋科学集刊》2002,(44):124-133

有关东海的虾类，刘瑞玉(1959，1963，1964)、董聿茂(1959，1980，1986)等已做过大量的调查研究。近10多年来，由于东海传统的主要经济鱼类资源衰退，捕食虾类的鱼类减少，因此，使虾类生存空间扩大，这有利于虾类资源的繁衍生长，使虾类资源发生量增多，数量增长较快。东海区三省一市近几年虾类产量达到80×104~90×104t，其中浙江省为60×104~70×104t，拖虾作业已成为东海区一大作业方式，对促进海洋捕捞业的发展起重要作用。20世纪80年代中后期，我们开展了东海虾类资源开发调查，尔后又继续与拖虾生产船相结合进行监测调查，积累了一些资料，本文就东海虾类生态群落结构与区系特征进行探讨。  相似文献   

Sediment–water interactions of natural oestrogens under estuarine conditions     

J. C. Bowman  J. L. Zhou  J. W. Readman 《Marine Chemistry》2002,77(4)

The natural human female hormones oestrone and 17β-oestradiol have been implicated in the disruption of endocrine systems in some wildlife adjacent to sewage effluents. The sorption behaviour of these two compounds under estuarine conditions was studied by spiking either 2.55 μg of oestrone or 2.65 μg of 17β-oestradiol in kinetic experiments. In equilibrium experiments, 3 ng of oestrone or 3.2 ng of 17β-oestradiol was added in each of the centrifuge tubes. Sorption onto sediment particles was relatively slow, with sorption equilibrium being reached in about 70 and 170 h for oestrone and 17β-oestradiol, respectively. The effects of a variety of environmental parameters on sorption were studied including salinity, sediment concentration (SC), the presence of a third phase, particle size and, also, surfactant concentrations. Results show that although salinity did not induce any statistically significant effect on the sorption of 17β-oestradiol, it did statistically enhance the sorption of oestrone, and a salting constant of 0.3 l mol⁻¹ was derived. The partition coefficient for both compounds decreased with increasing sediment concentration, a phenomenon that has been widely reported and attributed to the presence of colloids (which could enhance dissolved concentrations). In this paper, the true partition coefficients for sediment particles (K_p^true) and colloidal particles (K_c^true) have been calculated, and a K_p^true value of 141 and 102 ml g⁻¹ was obtained for oestrone and 17β-oestradiol, respectively. In addition, K_c^true values for oestrone (222×10² ml g⁻¹) and 17β-oestradiol (135×10² ml g⁻¹) were two orders of magnitude higher than their respective K_p^true values, suggesting that the colloidal particles are significantly stronger sorbents for natural oestrogens than sediment particles. Particles of different sizes were found to have different partition coefficients due to the strong relationships between partition coefficients for the two compounds and particulate organic carbon (POC) contents and specific surface areas (SSAs). The presence of a surfactant was shown to reduce the partition coefficients for the two compounds, although its concentrations being used were higher than those normally found in the natural environment.  相似文献   

棕囊藻囊泡的培养与去除研究     

晏荣军  尹平河  潘剑宇  吕颂辉  齐雨藻 《热带海洋学报》2006,25(3):69-71

对广东省珠海市海域球形棕囊藻Phaeocytstis globosa赤潮进行了现场采样及除藻研究,发现3种除藻剂对球形棕囊藻囊泡作用效果存在较大差异。对球形棕囊藻生活史及特征进行了研究,在实验室条件下培养出直径6mm球形棕囊藻囊泡,其生长周期约为14d。实验结果表明,囊泡的形成是球形棕囊藻应对恶劣环境的表现之一。  相似文献   

On the Polyps of the Common Jellyfish Aurelia aurita in Kagoshima Bay   总被引：1，自引：0，他引：1  

Hiroshi Miyake  Makoto Terazaki  Yoshiko Kakinuma 《Journal of Oceanography》2002,58(3):451-459

There is the natural habitat of polyps of the common jellyfish Aurelia aurita in the Taniyama area, Kagoshima Bay. We examined the attachment substrata, density, colony structure and strobilation of the polyps. The polyps were observed only on the horizontal undersurface of floating piers. They attached specifically to Mytilus shells, solitary ascidians, calcareous polychaete tubes, muddy amphipod tubes and the gap space that fouling animals peeled off the substrata. The polyp colonies were distributed in patches. Spatial distribution patterns of the polyps within their colonies were uniform. Strobilation occurred during late December to March, when water temperatures were 16–17°C, and a large number of ephyrae were released. An increase in man-made structures such as floating piers in coastal areas may lead to bloomings of Aurelia aurita medusae. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

基于蚁群智能的遥感影像分类新方法   总被引：5，自引：0，他引：5  

刘小平  黎夏  何晋强  艾彬  彭晓鹃 《遥感学报》2008,12(2):253-262

智能式遥感分类是遥感研究的新热点.提出了一种基于蚁群智能规则挖掘(ant-miner)的遥感影像分类新方法.遥感数据各波段之间存在较强的相关性,这种相关性往往会导致分类产生误差.而ant-miner算法中的信息素是基于规则整体性能的,信息素的动态更新能有效地处理相关性较强的数据,所提供的正反馈信息能纠正启发式函数缺陷所造成的错误.因此,蚁群智能算法应用于遥感分类具有一定的优势.将该方法用于广州市地区的遥感影像,取得了较好的分类结果.并与See5.0决策树方法及最大似然方法(MLH)进行了对比研究,实验结果表明,蚁群智能算法分类精度比后两者的分类精度更高.  相似文献   

华北克拉通破坏前的状态——对讨论华北克拉通破坏问题的一个建议   总被引：9，自引：4，他引：5  

翟明国 《大地构造与成矿学》2008,32(4)

中生代华北克拉通破坏是目前引人关注的研究课题。鉴于目前一些文章在表达克拉通状态时引用的地质图件不准确,忽略了华北克拉通从古至今的不同阶段的演化,不能正确的表达克拉通在破坏之前或之后的状态,本文强调华北克拉通破坏前的状态是研究的重要基础。华北克拉通是经历过多期克拉通化形成的。  相似文献   

辽西中生代燕鸟化石新材料的补充研究     

袁崇喜 《地质学报》2004,78(4):464-467

本文记述了一件产自辽宁锦州义县早白垩世九佛堂组燕鸟 (Yanornis)化石的新标本。研究标本不但自身保存非常精美 ,而且其嘴里还完整地保存了它捕获的最后一件猎物——吉南鱼 (Jinanichthys longi-cephalus)。该标本的研究 ,不仅对燕鸟的生存环境、生活习性、捕食类型等研究提供了直接的证据 ,而且对于探讨辽西热河生物群中脊椎动物的“集群死亡”的原因也具有重要的意义  相似文献   

Toxicity of tributyltin in the marine mollusc Mytilus edulis   总被引：1，自引：0，他引：1  

Josephine A. Hagger  Michael H. Depledge  Tamara S. Galloway 《Marine pollution bulletin》2005,51(8-12):811

Our previous studies have demonstrated that tributyltin (TBT) is genotoxic to the early life stages of marine mussels and worms. Here, the toxicity of TBT to adult organisms was determined using a suite of biomarkers designed to detect cytotoxic, immunotoxic and genotoxic effects. Exposure of adult mussels, Mytilus edulis, to environmentally realistic concentrations of TBTO for 7 days resulted in a statistically significant decrease in cell viability at concentrations of 0.5 μg/l and above. TBT had no effect on phagocytic activity or antioxidant capacity (FRAP assay). There was a statistically significant increase in DNA damage detected using the comet and micronucleus assays between the controls and 0.5, 1 and 5 μg/l of TBTO (P > 0.0005). Furthermore there was a strong correlation between DNA strand breaks (comet assay) and formation of micronuclei (P = 0.0005; R² = 61.5%). Possible mechanisms by which TBT could damage DNA either directly or indirectly are discussed including the possibility that TBT is genotoxic due to its ability to disrupt calcium homeostasis.  相似文献