Response-based extreme value analysis of moored offshore structures due to wave, wind, and current

Floating moored offshore structures have a significant future in offshore operations as an attractive economic alternative to fixed structures in deep waters and/or in areas where there is no existing infrastructure. This paper describes an analysis procedure based on the structure variable approach to estimate load and response values of a moored offshore platform at a given return period by taking into account the joint occurrence of wave, wind, and current. The results show that the most severe mooring loads may not occur when wind, wave, and current are collinear and are at their maximum design values, i.e., the 50- or 100-year case. It is recommended that the extreme mooring design loads for moored offshore systems should be determined through a range of physical or numerical simulations where wave, wind, and current are noncollinear and act with less severe magnitudes than the 50- or 100-year case. This recommendation has also been adopted in the ITTC/Ocean Engineering Committee recommendations to the ITTC Conference held in September 1996.     

Skid road effects on annual ring widths and diameter increment of fir (Abies bornmulleriana Mattf.) trees

This study examines annual ring widths, diameter growth and increment differences of trees at a skid road and the undisturbed area in a pure plantation fir (Abies bornmulleriana Mattf.) forest and compare these data with annual ring widths diameter growth and increment of trees at the skid road edge and undisturbed forest area. The trees growing there commonly display better growth and diameter increment than the trees growing on the skid road. Tree growth and increment on the undisturbed area was found to be about 60% greater than the skid road.     

一种货船横截曲线的近似方法

本文给出了一种估算货船横截曲线及初步设计阶段预测静稳性的公式。这一预测技术通过系统地变化的货船系列数据回归分析后获得。为了完成这一程序 ,一些货船线型采用 6 0系列。这一预测技术的数学模型是作为设计参数的函数构造的 ,这些设计参数如船长、船宽、型深、吃水和方型系数。本文发展的这一预测方法也能用于决定特定船型参数和对货船稳性的影响。这一方法已应用于一艘货船 ,并且将实船的结果与那些回归值作了比较。     

Adaptability and vulnerability of zooplankton species in the adjacent regions of the Black and Marmara Seas

During 2005–2008 species composition, abundance patterns, natural mortality rates and salinity effects on zooplankton were studied in the Bosphorus regions of the Black and Marmara Seas. The tendencies to diminish for abundance and biomass of the Black Sea originated zooplankton species and to increase for the proportion of their carcasses in the direction from the Black Sea toward the Marmara Sea were found. The mortality in the Black Sea species increased with depth in the Marmara Sea. The contribution of organic matter of carcasses of the Black Sea originated organisms to bacterial processes in the deep strata of the Marmara Sea was estimated. Different salinity and temperature regimes restrict mutual penetration of the species in these seas.     

Simulations of biological production in the Rhodes and Ionian basins of the eastern Mediterranean

The biological production characteristics of the Rhodes and western Ionian basins of the eastern Mediterranean are studied by a one-dimensional, coupled physical–biological model. The biological model involves single aggregated compartments of phytoplankton, zooplankton, detritus as well as ammonium and nitrate forms of the inorganic nitrogen. It interacts with the physical model through the vertical eddy diffusivity which is calculated using the Mellor–Yamada level 2.5 turbulence parameterization. The model simulations demonstrate the importance of the contrasting physical oceanographic characteristics of these two basins on affecting their yearly planktonic structures. The annual primary production in the Rhodes basin is estimated as 97 g C m² yr⁻¹ which is comparable with the northwestern Mediterranean. The western Ionian basin, on the contrary, possesses only 10% of the Rhodes' productivity and therefore represent a most oligotrophic site in the eastern Mediterranean. The Rhodes basin reveals a strong bloom in early spring, typically in March, a weaker bloom in early winter, typically in January, and a subsurface production below the seasonal thermocline during summer. This structure is slightly modified in the western Ionian basin, and the early winter and early spring blooms are merged to cover the entire winter. These results are supported favorably by the available observations both in their magnitudes and timing.