Experimental investigation of response stability and transition behaviour of a nonlinear ocean structural system

This study experimentally investigates the nonlinear response stability and transition behaviour of a submerged, moored ocean structural system which consists of a spherical buoy and attached multi-point mooring lines. The system is excited by a periodic wave field in a closed channel. System nonlinearities include complex geometric restoring (stiffness) force and coupled fluid-system interaction exciting forces. Experimental set-up, operating procedures and analysis of the measured results are presented. Characteristic motions observed include harmonic, subharmonic and ultraharmonic responses, which demonstrate a signature of the intricate pattern of the nonlinear global behaviour. Good agreements between the measured and most predicted responses are demonstrated in both time and frequency domains. These results confirm the validity of the analytical model presented and calibrate the accuracy of the existing numerical predictions. Primary and secondary resonances in the response are identified via frequency response curves. Response bifurcation cascades are observed in the experimental results and the possible existence of higher-order nonlinear responses is inferred.     

Significant load and green water on deck of offshore units/vessels

In this paper the probability of green water occurrence is investigated by taking into account the threshold of the vertical relative motion exceeding the freeboard. The number of wetting of the unit/vessel is predicted using probabilistic method. This paper compares the significant load, due to shipping of green water with the works of other researchers, and the loads are found to be close with the results presented in this paper. There is no direct relation between the velocities in the waves and the water velocity over the deck. The water velocities around the bow are heavily distributed by the presence of the bow. This scenario makes the flow very complex for schematic modelling.     

Mass extinction of ocean organisms at the Paleozoic-Mesozoic boundary: Effects and causes

At the end of the Permian, at the boundary between the Paleozoic and Mesozoic (251.0 ± 0.4 Ma), the largest mass extinction of organisms on the Earth occurred. Up to 96% of the species of marine invertebrates and ∼70% of the terrestrial vertebrates died off. A lot of factors were suggested and substantiated to explain this mass mortality, such as the disappearance of environmental niches in the course of the amalgamation of the continental plates into Pangea, sea level fluctuations, anoxia, an elevated CO₂ content, H₂S intoxication, volcanism, methane discharge from gas-hydrates, climate changes, impact events (collisions with large asteroids), or combinations of many of these reasons. Some of these factors are in subordination to others, while others are independent. Almost all of these factors developed relatively slowly and could not cause the sudden mass mortality of organisms globally. It could have happened when large asteroids, whose craters have been discovered lately, fell to the Earth. It is suggested that the impact events “finished off” the already suppressed biota. A simultaneous change in many of the factors responsible for the biodiversity, including those not connected in a cause-and-effect relationship, proves the existence of a common extrater-restrial cause that affected both the changes in the internal and external geospheres and the activation of asteroid attacks (the Sun’s transit of spiral arms of our galaxy, the Sun’s oscillations perpendicularly to the galactic plane, etc).     

Effect of skewness and kurtosis of sea-surface elevations on the accuracy of altimetry surface level measurements

We assess the influence of changes in the skewness and kurtosis of the distribution of elevations on a rough sea surface that were observed in field conditions on the accuracy of the recovery of the sea-surface level along the satellite trace. For different values of a significant height of surface waves, we obtain numerical estimates for the bias in relief recovery due to the simultaneous variation in skewness and kurtosis. It is shown that, with a decrease in kurtosis, the effect of skewness changes on the accuracy of altimetry measurements of the level increases. We note the limitations of the Gram-Charlier model in simulating the radar waveforms return from the sea surface.     

Treatment of Hydrodynamic Loading for Random Sea State

- In order to employ cost effective frequency domain analysis for off-shore structures treatment of hydrodynamic loading is essential. Drag and inertia dominated, resonating and antiresonating cases under random sea states are analyzed to highlight the implications and relative merits of four salient linearization techniques.     

莱州湾东部滨海水域砂金分布特征

通过对莱州湾东部滨海水域地球物理和地质钻综合调查，业已查明该海区地质的构造和古地理环境特征，并发现区内砂金分布较普遍，本文从砂金分布的地貌单元，沉积物类型，砂金成因类型，物质来源，古气候，构造作用，砂金成因等诸方面，研究了该海域内砂金特征。     

Metallothionein-like proteins induced by cadmium stress in the scallop Mizuhopecten yessoensis

Organisms have evolved a cellular response called stress protein response that increases their tolerance in adverse environmental conditions. Well known stress proteins that bind essential and toxic metals are metallothionein (MT). The scallop Mizuhopecten yessoensis is the most interesting organism because it is able to accumulate toxic cadmium in its digestive gland. However, in the tissue of the digestive gland of Mizuhopecten yessoensis MT (metallothioneins) have not been found. Eastern scallops, Mizuhopecten yessoensis, were collected from two locations ?? one clean and one polluted site. The concentrations of cadmium (Cd), copper (Cu) and zinc (Zn) were measured in the digestive gland. There was a significant increase in Cd concentrations in this studied tissue. We found that in the presence of cadmium Mizuhopecten yessoensis can induce high molecular proteins. The results of experiments have shown that Cd-binding ligands have a number of properties similar to MT: acetone and temperature stability; the ability to bind some metals, including Cd, Cu and Zn. Protein chromatography (FPLC, Superosa 12) from the digestive gland of scallop M. yessoensis has shown that cadmium is associated with high molecular weight Cd-binding proteins (72 kDa and 43 kDa). The major cadmium-binding protein 72 kDa is glycoprotein. In experiments we have demonstrated that Cd-binding proteins can be induced when there is cadmium exposure. The results of this study strongly suggest that the far eastern scallop Mizuhopecten yessoensis has a unique and well-developed system for the detoxification of heavy metals and it allows for biochemical systems to be maintained in a relatively stable manner in the presence of heavy metals.     

Thickness of the mixed bottom layer in the Northern Atlantic

The thickness of the mixed bottom boundary layer (BBL) has been analyzed based on the CTD data at transoceanic sections in abyssal waters of the Northern Atlantic. The measurements were carried out at two transoceanic sections approximately along 48° N (ASV-99) and 5° N (AI-2000) in 1999 and 2000. These data, and the WOCE data obtained at four zonal sections (AR7E and AR12 along 57° N, AR01 along 24.5° S, and A06 along 7.5° N), were used for the calculation of the statistical characteristics of the BBL??s thickness H _B . The probability distribution function F(H _B ) was close to lognormal. The mean value ??H _B ?? at different latitudes was in the range from 30 to 60 m. The averaged BBL thickness = 46.1 m. The BBL??s thickness was about 1% of the ocean??s depth D; the ratio H _B /D was the minimum (0.8%) near the equator and increased up to 1.6% in the polar latitudes.     

Seasonal dynamics and Trophic interactions of phytoplankton and zooplankton in the Vistula Lagoon of the Baltic Sea

The trophic relationships of the phytoplankton and zooplankton in the Vistula Lagoon in 2008?C2010 were investigated. In the current period, the lagoon is an eutrophic water body with summer blooms of blue-green algae. The trophic level of the Vistula Lagoon influences both the composition and quantitative characteristics of the communities of phytoplankton and zooplankton and the trophic relationships between them. In the analyzed period, the consumption of phytoplankton by the zooplankton on the average in the growing season was 28%, which is 1.5 times higher than in the late 1970s. The high grazing pressure of the zooplankton on the phytoplankton reduces its biomass, production, and the intensity of the blooming by the blue-green algae in the Vistula Lagoon.     

Change in biochemical and morphological characteristics of Lonicera caerulea in tectonically active zone of the Dzhazator River Valley (Altai Mountains)

Local geophysical and geochemical anomalies affect the polymorphism of taste variations, berry shape, and content of some biologically active substances in Lonicera caerulea leaves in the tectonically active Altai Mountains (Dzhazator River basin).