功能叠加式水轮机微机调速器应用

指出双微机调速器在可靠性方面存在的问题，提出一种功能叠加式高可靠性微机调速器新型结构。从单微机、双微机和三微机调节器可靠性指标分析比较得出，限制双微机可靠性提高的关键在于自动转换器可靠性模型结构过于复杂，应将改善微机调速器可靠性的重点放在优化系统功能、简化系统结构上来。合理的系统功能划分是提高可靠性的关键，在发生故障时，各功能模块工作应保持相对的独立性，这样能够很好地处理系统功能和可靠性之间的协调关系。     

甲酸诺卜酯和诺卜甲基醚的~(13)C化学位移分析

由β-蒎烯合成诺卜醇,再用诺卜醇与甲酸合成甲酸诺卜酯,GC纯度为96.9%产物的产率为88.3%;用相转移催化法由诺卜醇与碘甲烷合成诺卜甲基醚,GC纯度为93.1%产物的产率为89.8%,诺卜醇的这2个衍生物都具有较好的香气特性,它们的结构均用IR,MS,1H NMR及13C NMR分析进行了表征.对2个衍生物13C化学位移的分析表明:它们的C1--C2--C3--C4--C5-部分处在同一个平面上,整个6,6-二甲基双环[3.1.1]庚-2-烯部分呈"Y"形,它们可被看作阿朴蒎烯在C2-发生取代的衍生物,取代基对13C化学位移的影响主要集中在C2-,C1-和C3-,对其它碳原子的影响比较小.     

Overlaps in habitat use of fishes between a seagrass bed and adjacent coral and sand areas at Amitori Bay, Iriomote Island, Japan: Importance of the seagrass bed as juvenile habitat

ABSTRACT:   To clarify faunal overlap between a seagrass bed and adjacent coral and sand areas, and the number of reef fishes utilizing the seagrass bed as juvenile habitat, visual censuses were conducted at Amitori Bay, Iriomote Island, Japan. The numbers of species and individuals of fishes were significantly higher in the coral area than in the seagrass bed and sand area. Cluster and ordination analyses based on the number of individuals of each species demonstrated that the fish assemblage structure differed among the three habitats in each season, but with some overlaps. Approximately half the seagrass bed fishes occurred in the adjacent coral area (coral–seagrass species). Dominant species of coral–seagrass species utilized the seagrass bed as an important juvenile habitat. Thus, some overlaps in habitat use were present between the seagrass bed and adjacent coral area. Despite such overlaps, however, coral–seagrass species accounted for only approximately 15% of coral reef fishes overall, indicating that most of the latter hardly utilize the seagrass bed directly in the study area.     

珠海“蟹夹”渔具的调查分析

根据“蟹夹”的渔具结构和捕捞原理,将其定名为漂流延绳弹夹笼壶。介绍了“蟹夹”的捕捞对象和作业方式,对其渔具性能进行了分析,对“蟹夹”渔具管理提出了若干意见。     

Perceptions of resource users and managers towards fisheries management options in Kenyan coral reefs

Abstract  The perceptions of Kenyan resource users and managers towards gear and area management were examined through face-to-face interviews to identify areas of agreement and disagreement and compare with compliance. Opinions were sought about gears that sustained fish catch, gears discouraged by the government and traditional leaders, and the benefits of area management were sought. There was good agreement among most groups and traditional leaders about the gears discouraged by government, with beach seines and spear guns the most commonly listed. This indicates good agreement between government and traditions, promoted by recent government legislation, but compliance was poor since nearly two-thirds of fishers used these recently prohibited gears. This was due, in part, to lesser agreement concerning gears that promote a sustainable fishery, with spear guns and beach seines scaled low, but moderately supported in this respect by those fishers that use these gears. These gears persist because of the lack of shared evidence about the yields and sustainability of the various gears and social and economic aspects, such as increased competitiveness and decreased costs of the gears. There is evidence that beach seines lower yields but this gear persists because it is more competitive and has lower costs to the user than the other gears. Spear guns also persist because young and poor fishermen, who cannot afford costs associated with other gears, use them. Government employees scaled the benefits of area, and particularly closed area, management, higher than fishers, which is an issue of conflict but, nonetheless, has good compliance because of the long history of closed area management. For both types of management, shared perceptions alone were insufficient to achieve high compliance, and active enabling and enforcement by managers is needed.     

Migration of landlocked brown trout in two Scandinavian streams as revealed from trap data

Abstract –  Anthropogenic barriers that may interfere or prevent fish migration are commonly found in streams throughout the distribution of salmonids. Construction of fish passages in streams is a common solution to this problem. However, the goal with fish passages is often, at least in Scandinavia, to allow Atlantic salmon ( Salmo salar L.) and migratory brown trout ( S. trutta L.) to get access to spawning areas above these barriers. Hence, the fish passages may often only be open during the spawning migration of salmonids (late summer to autumn). We present data, on wild brown trout migration, from two trapping systems in two Scandinavian streams showing that intra- and interstream migrations are common throughout the summer and autumn. Moreover, differences in size were found between trap-caught trout and electrofished trout where trapped trout were generally larger than electrofished trout. We suggest that the current regime with fish passages only open parts of the year can have negative effects on populations by depriving trout from the possibility to perform migrations throughout the year.     

A role for partially protected areas on coral reefs: maintaining fish diversity?

• 1. Completely banning fishing from coral reefs is now accepted to have significant benefits for marine biodiversity and in many cases, fisheries. However, the benefits of regulating fishing on coral reefs, by restricting the methods used, or the total amount of fishing, are less well understood, even though such regulations are much more likely to be supported by fishermen.
• 2. This study assesses whether banning illegal, destructive fishing methods and reducing the numbers of fishermen visiting from outside an area benefits a coral reef fishery, despite unregulated fishing by local fishermen using non‐destructive methods.
• 3. The abundance, biomass, mean length, and species richness of nine commercially important fish families are compared across ten independent patch reefs inside and outside the 470 km² Menai Bay Conservation Area in Zanzibar, Tanzania.
• 4. Even after taking into account the effect of differences in habitat and the distance between reefs, 61% (±19.7%) more fish species were found in regulated than unregulated reefs. Fish abundance, biomass, and length were not affected, suggesting that banning destructive fishing may improve biodiversity, but that further regulations may be required to improve fish stocks.Copyright © 2011 John Wiley & Sons, Ltd.

     

North–south contrasts in decadal scale variations in lower trophic-level ecosystems in the Japan Sea

Regional comparisons of interannual variations in springtime lower trophic-level ecosystems were made for northern subarctic regions, and for southern Tsushima Current regions of the Japan Sea, based on archival hydrographic and biological data sets collected from the mid-1960s to the early 1990s. Variations related to the Pacific Decadal Oscillation were detected for plankton biomass in both northern and southern regions, although there were regional differences with respect to mechanisms and timing. Springtime stratification increased after the late 1970s in the north, roughly coinciding with the northern Pacific regime shift in 1976/77. Stratification also increased due to warming in the south in the early 1980s, several years after the 1976/77 regime shift. Responding to the increase in stratification, springtime biomass of phytoplankton and zooplankton increased in the north and decreased in the south. Principal component analysis revealed that hydrographic conditions during spring, rather than winter, determined springtime phytoplankton biomass. In northern regions, spring phytoplankton production may be enhanced by increased light availability, due to mixed layer stabilization. In the south, where background nutrient concentration within the water column was low, increases in stratification were likely to limit nutrient supply to the surface layer, resulting in decreases in phytoplankton production. A positive relationship between phytoplankton and zooplankton biomass suggested bottom-up control of secondary production in northern regions. The nature of the links between phytoplankton and zooplankton production was not clear in southern regions, where hydrographic conditions during winter seemed to be responsible for variations in springtime secondary production.