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991.
Fish sonars have long been used to survey and monitor migratory salmon in rivers and at sea. However, research has been lacking in the development of algorithms to extract fish tracks from data collected in a riverine or oceanic environment. Current fish trackers, based on a pulse-to-pulse tracking method, only work well under ideal conditions when targets are well separated and the signal-to-noise ratio is high. Fisheries biologists often have to identify fish traces visually from raw echograms. This approach is both labor-intensive and time-consuming, limiting the usefulness of hydroacoustic techniques for fisheries management. This paper presents a fish-tracking algorithm which sorts randomly distributed echoes into coherent fish traces. Fish counts obtained with the algorithm compare well with visual counts at two quite different sites in the Fraser River watershed. The key features of the algorithm are: (1) the linking mechanisms among sequential fish echoes are range-dependent; (2) the growth echo for a developing track depends not only on its space-time relation with the previous track echo (the pulse-to-pulse statistics) but also on its relation to the entire track being constructed; (3) there are a total of only five echo-association criteria in the algorithm; (4) the simplicity of the algorithm structure provides a convenient platform for implementing specific and sophisticated tracking criteria to meet specific needs; and (5) the user can fully control the performance of the algorithm by choosing values for the 11 well-defined tracking parameters 相似文献
992.
GRV 90027 is a Martian lherzolitic shergottites (L-S) containing poikilitic, non-poikilitic, and melted pocket components. GRV 99027 is mainly composed of olive (55 vol%) and pyroxene (37.5 vol%), with minor maskelynite (6 vol%) and chromite (1.5 vol%), and trace whitelockite and troilite, ect. In this paper, the mineralogy and petrology of GRV 99027 are reported; in addition, the geochemical characteristics of the REEs and H isotopes in the GRV 99027 are also further investigated. The ΣREE in GRV 99027 is relatively low; HREEs are enriched in olivine and pyroxene grains; LREEs are enriched in plagioclase with a high positive Eu anomaly. High ΣREE value is found in rare mineral whitlockite (less than 0.2 vol%), LREE≈HREE, and whitlockite has a negative Eu anomaly. The REE distribution patterns of the whole -rock of GRV 99027 is similar to but different from that of other L-S Martian meteorites, indicating that they came from different location of Mars. GRV 99027 has a high δD value. Different water-bearing minerals give different contribution for δD value. The δD of phosphates generally does not correlate with water content, and δD has a weak negative correlation with water content. GRV 99027 can be classified as an L-S Martian meteorite based on mineralogical assemblage patterns, REE distribution patterns, and hydrogen isotope. The isotope data of Sr, Nd, Pb, Os and REE from other L-S Martian meteorites were collected to discuss the formation history of the GRV 99027. Similar to other L-S Martian meteorites, GRV 99027 originated from part of Mar's mantle; during one strong impact event about 4M years ago, the meteorites were ejected from deep mantle into space, and traveled for a different duration in space (indicated by different cosmic exposure time), and captured by the Earth later in different time, ultimately falling on the Antarctica as L-S Martian meteorites. 相似文献
993.
Preparation by enzymolysis and bioactivity of iron complex of fish protein hydrolysate (Fe-FPH)from low value fish 总被引:6,自引:0,他引:6
Preparation of Fe^2+ chelate of fish protein hydrolysate (Fe-FPH) obtained from low value fish proteins was introduced and its bioactivity was studied by compound enzymolysis. The optimum conditions for hydrolysate chelating Fe^2+ are DH (degree of hydrolysis) at 5%, pH 7.0, 20℃ and 15 min chelating time for FM (material not being defatted). Four types of Fe-FPH including CA (deposit after chelating), CB (deposit in 50% of absolute ethanol solution), CC (suspended deposit in 80% of absolute ethanol solution), and CD (bottom deposit in 80% of absolute ethanol solution) were fractionated with absolute ethanol from FM. Structural analysis through infra-red spectrum revealed that Fe^2+ was combined strongly with amino-group and carboxyl-group in each chelate and each Fe^2+ could form two five-member ring structures. All of the four chelates were shown more significant antioxidative activity and can be used as natural hydrophobic and hydrophilic antioxidant. Among all the chelates, the CB possesses the most effective antioxidative activity at 92% as high as that of a-tocopherol. Among all Fe-FPHs, only CD showed the most effective antibacterial activity against Escherichia coli, Staphylococcus aureus, Salmonella typhi, and Bacillus subtilis and can be used as natural antibacterial. It provides a more effective way for utilization of low value fish proteins and key information of Fe-FPH as additive in food industry. 相似文献
994.
This article discusses how the Chinese seafood industry will affect the rest of the world's fishing industries. The analysis is based on theories of economic comparative advantage, the international division of labour and the internationalization process related to trade activities. Given the increasing domestic demand for fish in China, the limited availability of domestic fish stocks and less success for farmed marine fish in China are considered some of the most important factors in restricting the growth in Chinese seafood production. The necessity of raw fish imports into China may increase pressure on global fish stocks and international fish prices, resulting in tighter supplies worldwide and higher seafood prices for the Chinese. Sustainable fish harvests and trade require stronger fishery management, in particular in the relations between seafood companies and governments along the entire international value chain supplying China. Such structural changes may allow new value-added possibilities for fish farming and the upgrading of certain fish species for human consumption that were previously utilized purely for fish feed. 相似文献
995.
应用GPS数据确定法和地震矩率法计算了川滇南部主要活动断裂分段特征地震复发间隔,在此基础上,运用实时概率模型计算了各条断裂未来10年、30年、50年、100年的发震概率.结果表明,川滇南部未来百年特征地震复发的可能性按概率值大小依次为:安宁河断裂带小相岭段,小江断裂东川段,安宁河断裂带冕宁西昌段,则木河断裂带,丽江-小金河断裂丽江宁蒗段,小江断裂带华宁段,小江断裂带嵩明宜良段和红河断裂带北西段. 相似文献
996.
超压释放及其对油气运移和聚集的意义 总被引:22,自引:5,他引:22
从增压作用和减压作用相互关系的角度,探讨了超压释放的定义-超压趋向于静水压力降低的作用,根据超压释放的结果,超压释放可分为不完全释压和完全释压,依突破压力封闭的动力,超压释放可分为主动释压和被动释压。有两类不同的成因的超压释放通道,分别是自振通道和它拓普通,超压释放的主要机制有断裂活动,水力压裂,底辟作用,渗透性岩层输导作用,渗透作用,剥蚀作用和人为作用。超压释放提供了油气运移的现实动力,开拓了油气运移的通道,促进了生烃作用,有利于超压系统内的油气成藏,影响油气的分布。超压释放分析为探讨超压与油气的运聚提供了有效的方法。 相似文献
997.
Anthropogenic lead (Pb) has been found in Antarctic seawater, surface snow and ice-cores. Here, we analyzed a 3,000-year record of lead concentration in lake sediments affected by penguin droppings. We found that lead concentration in penguin droppings has significantly increased during the last 200 years, especially in the last 50 years, as compared to low and stable lead levels prior to the Industrial Revolution. This clearly indicates that global environmental pollution has influenced the Antarctic ecological system. Heavy metal (Pb) may find its way into the food web, bioaccumulate, and be passed along the chain to penguins. 相似文献
998.
999.
用1957~1999年广东省19个代表站4~6月降水资料和500hPa高度场资料,着重分析和讨论了广东省前汛期异常旱、涝年的同期和前期500hPa合成平均场的主要差异,以及前期关键月、关键区的特点,为广东省前汛期异常旱、涝的预测提供判别依据。 相似文献
1000.
塔里木盆地志留系层序地层特征 总被引:20,自引:7,他引:20
通过对塔里木盆地西缘露头、盆内钻井、测井和地震资料以及大量室内分析化验资料的层序地层综合分析,可将志留系划分成五个三级层序,志留系沉积层序厚度40--155m。层序界面多为分布范围较广的区域性或局部不整合。层序叠置样式可用具陆棚坡折的I型层序地层样式来描述。每个沉积层序可由完整的低位、海侵和高位体系域组成或由其中的一个、两个体系域组成。体系域边界主要依据滨岸上超点位置、岩性组合及准层序叠置样式变化来确定。低位体系域由向上粒度变细、砂岩厚度向上减薄的准层序组成;海侵体系域表现为向上泥岩厚度加大、砂岩厚度减薄的叠置特点;高位体系域表现为加积--进积沉积特征。志留纪,研究区接受了滨外陆棚及滨岸、海湾潮坪沉积,发育典型的海相沉积构造,表现出明显的旋回特征。 相似文献