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771.
Typology of a Great River Using Fish Assemblages: Implications for the Bioassessment of the Danube River
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T. Erős V. Bammer Á. I. György L. Pehlivanov M. Schabuss H. Zornig A. Weiperth Z. Szalóky 《河流研究与利用》2017,33(1):37-49
Matching habitat typology and ecological assemblages can be useful in environmental management. We examined whether a priori defined riverine sections correspond with distinct fish assemblage types along the >2000 km long course of the Danube River, Europe. We also tested whether different sampling methods (i.e. day and night inshore electric fishing and offshore benthic trawling) provide consistent typological results. Analysis of assemblage similarities, indicator species analysis, non‐metric multidimensional scaling (NMDS) and k‐means analyses indicated that fish assemblages of the a priori defined Upper‐, Middle and Lower‐Danubian sections differed slightly, but within class variability was high. Although indicator species analysis showed that the Upper‐Danube belongs to the barbel (Barbus barbus) zone and the Middle‐ and Lower Danube belong to the bream (Abramis spp) zone, indicator values of the character species were generally low. The NMDS analyses suggested a weak gradient in assemblage structure along the course of the river with relatively high variability between neighbouring sites. K‐means analyses revealed that many sampling sites were in a different class than the a priori defined sections, and classifications at other group numbers did not lead to better classification outcome. Overall, the results do not suggest clearly distinguishable assemblage types with distinct boundaries in the potamal section of a great river. Nevertheless, the division of the potamon to smaller sections may explain some variability in fish assemblage structure, and could be used for bioassessment purposes. The study also shows the importance of multihabitat and multigear surveys in the typological assessment of great rivers. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
772.
“四合一”金属切削液的研制 总被引:1,自引:0,他引:1
研制了一种适合多种金属(包括黑色金属,铜,铝)切削的“四合一”金属切削液,兼具冷却,润滑,清洗和防锈多重功效。 相似文献
773.
This study presents an approach for semi-automated classification of tree species in different types of forests using first and second generation ADS40 and RC30 images from two study areas located in the Swiss Alps. In a first step, high-resolution canopy height models (CHMs) were generated from the ADS40 stereo-images. In a second step, multi-resolution image segmentation was applied. Based on image segments seven different tree species for study area 1 and four for study area 2 were classified by multinomial regression models using the geometric and spectral variables derived from the ADS40 and RC30 images. To deal with the large number of explanatory variables and to find redundant variables, model diagnostics and step-wise variable selection were evaluated. Classifications were ten-fold cross-validated for 517 trees that had been visited in field surveys and detected in the ADS40 images. The overall accuracies vary between 0.76 and 0.83 and Cohen's kappa values were between 0.70 and 0.73. Lower accuracies (kappa < 0.5) were obtained for small samples of species such as non-dominant tree species or less vital trees with similar spectral properties. The usage of NIR bands as explanatory variables from RC30 or from the second generation of ADS40 was found to substantially improve the classification results of the dominant tree species. The present study shows the potential and limits of classifying the most frequent tree species in different types of forests, and discusses possible applications in the Swiss National Forest Inventory. 相似文献
774.
775.
Antenna current optimization for optimal antenna design in different frequency bands using VSO‐NM algorithm
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In this article, the antenna partial gain to ‐factor based on the antenna current optimization is used as figure of merit for antenna design proposing an efficient global hybrid technique that combining very simple optimization (VSO) and Nelder‐Mead (NM) algorithm. To validate the strength of the approach, a set of three antennas operating within different frequency bands of super high frequency, submillimeter, and light spectrum are addressed and optimized. The antennas are analyzed completely using finite difference time domain method. The results showed the strength of the approach of optimizing antenna gain to ‐factor based on antenna current optimization using the hybrid VSO‐NM algorithm in different frequency bands. Compared to stand‐alone VSO, the hybrid VSO‐NM algorithm showed the ability to reduce the processing time on average by 58.73% in addition to enhancing the search capability by 43%. 相似文献
776.
ABSTRACTVery small island states face unique challenges, such as volatile economies, increasing vulnerability to natural disasters, particularly with raising seas, increases their dependence on the world economy. Despite their growing use of ICTs, the results are mixed in terms of the effect of growing ICT usage on income growth. This paper investigates how growth in ICT usage may enable growth in per capita Gross Domestic Product (GDP) in very small island states by analyzing the effects of average ICT usage on GDP growth based on the most recent data available from the World Bank and from the International Telecommunications Union (ITU). Following an analysis of data over four years of 32 very small island states, this paper identifies an ICT multiplier effect that may explain and predict the relationship between average ICT usage and GDP growth. By showing how the ICT multiplier effects may be connected to GDP growth, this paper adds to what we know about the relationship between these two indicators in very small island states. This has implications for how government interventions can enable ICT capacity to bring about GDP growth. 相似文献
777.
Condition monitoring of the machining process is very important in today's precision manufacturing, especially in the electrical discharge machining (EDM). This paper introduces a fuzzy-based algorithm for prediction of material removal rate (MRR), tool wear ratio (TWR), and surface roughness (Rz, Rk) in the EDM and ultrasonic-assisted EDM (US/EDM) processes. In this system, discharge current, pulse duration, and ultrasonic vibration of tool are the input variables and outputs are MRR, TWR, Rz, and Rk. The proposed fuzzy model in this study provides a more precise and easy selection of EDM and US/EDM input parameters, respectively for the required MRR, TWR, Rz, and Rk, which leads to better machining conditions and decreases the machining costs. The fuzzy modeling of EDM and US/EDM were able to predict the experimental results with accuracies more than 90%. 相似文献
778.
研究压水堆一回路管道小小破口失水事故叠加辅助给水失效导致的高压堆芯熔化严重事故进程,对比验证不同严重事故缓解措施入口温度条件下一回路卸压缓解途径的充分性和有效性,并确认较佳的一回路冷却系统(RCS)降压途径。结果显示,以低于650℃的温度作为降压缓解措施入口条件,可及时恢复可能的堆芯冷却能力。一、二回路卸压效果分析表明,考虑了长期衰变热移出注水流量和堆芯过冷度要求,较佳的卸压配置为初期打开一列稳压器卸压阀,同时迅速恢复辅助给水并开启蒸汽发生器卸压阀。 相似文献
779.
780.
Michel Babbit 《国际钢铁研究》2006,77(9-10):620-626
This paper is a short review on some recent developments regarding steels for automotive use. A new precoated steel suitable for to hot stamping processing has been developed, which is most appropriate for producing anti‐intrusion parts. Another evolution of precoated steels is a new inorganic treatment (NIT), which has proved to be efficient in increasing the stamping productivity of precoated steels. In the field of corrosion protection, a new generation of thin organic coatings has been implemented and in the future Zn‐Mg metallic coatings will help to save auxiliary anticorrosion measures such as wax and mastics. To offer steels with high stiffness but low weight, Arcelor has developed a new multimaterial sandwich which shows a good potential for large panels due to its high stiffness. Finally, some breakthrough steel products are discussed as possible candidates for mid/long term applications. 相似文献