固定式海洋平台利用TLD的减震研究

本文研究固定式海洋平台利用调谐液体阻尼器（ＴｕｎｅｄＬｉｑｕｉｄＤａｍｐｅｒ，简称ＴＬＤ）减小地震反应的方法。首先探讨了调谐频率比、激磁频率比对减震效果的影响，在此基础上建立了ＴＬＤ——平台系统的力学模型和运动方程，通过数值计算验证了该方法的有效性     

Magnitude-frequency relationship of coastal sand delivery by a southern California stream

Coastal sand delivery by a stream in southern California is estimated based on a numerical model which stimulates unsteady flow, sediment transport, and the associated channel adjustments for a stream-delta system. An average annual sediment yield of 51,400 m³/yr is estimated for the San Dieguito River, which drains a semiarid watershed controlled by dams. Of the total sand delivery by the stream, 20.5 percent is contributed from floods greater than the 100-year flood; 17.6 percent from those between the 50- and 100-year events; 28.4 percent from those between the 25- and 50 year floods; and 33.5 percent from those smaller than the 25-year flood.     

An optimized method for automated analysis of algal pigments by HPLC

A recent development in algal pigment analysis by high-performance liquid chromatography (HPLC) is the application of automation. An optimization of a complete sampling and analysis protocol applied specifically in automation has not yet been performed. In this paper we show that automation can only be successful if the various methodological aspects of the sampling and analysis protocol are considered in coherence. We introduce an optimized protocol that involves freeze-drying of the sample, subsequent extraction in 90% acetone and the application of water-packing during analysis. The method was evaluated on both natural plankton populations and a broad spectrum of microalgal cultures: Thalassiosira weisflogii (Bacillariophyceae), Emiliania huxleyi (Prymnesiophyceae), Phaeocystis globosa and Phaeocystis antarctica (Prymnesiophyceae) and Pyramimonas sp. (Prasinophyceae). Whereas pigment extracts were unstable in methanol, with recorded chlorophyll a losses from 10% to 60% per day, pigment degradation rates in acetone were generally less than 1% over 18 h storage in the autosampler (4 °C). In addition, it was found that the extraction efficiency of acetone significantly increased upon freeze-drying prior to extraction. Increases as high as 50–60% were measured in P. antarctica. The application of water-packing of the sample during injection resulted in improved peak shape and peak separation, without diluting the pigment concentrations. Automation is especially beneficial for application in the field, when mixed algal assemblages and low biomass put a high demand on the sensitivity as well as reproducibility of the method.     

Analysis of medaka cytochrome P450 3A homotropic and heterotropic cooperativity

We have previously demonstrated that medaka CYP3A is associated with metabolism of several endobiotics including steroids and bile acids. In this study, we demonstrate that medaka CYP3A catalysis exhibits unusual kinetic behaviors consistent with allosteric interaction which cannot be described by hyperbolic kinetic models. Using 7-benzyloxy-4-(trifluoromethyl)-coumarin (BFC) and nonylphenol as CYP3A substrates, we describe both homotropic and heterotropic cooperative interactions. Given the role of CYP3A in maintaining the homeostatic balance for numerous endobiotics, enzymatic activation/inhibition by endocrine disruptors (EDCs) represents a putative (non-genomic) mechanism for endocrine disruption.     

Constraining the origin and evolution of confined turbidite systems: southern Cretan margin,Eastern Mediterranean Sea (34°30–36°N)

Bathymetric, 9.5-kHz long-range sidescan sonar (OKEAN), seismic reflection and sediment-core data are used in the analysis of two tectonic troughs south of Crete, Eastern Mediterranean Sea. Here, up to 1.2 s two-way travel time (TWTT) of strata have accumulated since the Middle Miocene in association with extension in the South Aegean region. The study area comprises >100-km- long by >25-km-wide basins filled by sediments subdivided into two seismic units: (1) an upper Unit 1 deposited in sub-basins which follow the present-day configuration of the southern Cretan margin; (2) a basal Unit 2, more than 500 ms (TWTT) thick, accumulated in deeper half-graben/grabens distinct from the present-day depocentres. Both units overlap a locally stratified Unit 3 comprising the pre-Neogene core complex of Crete and Gavdos. In this work, the interpreted seismic units are correlated with the onshore stratigraphy, demonstrating that denudation processes occurring on Crete and Gavdos in response to major tectonic events have been responsible for high sedimentation rates along the proximal southern Cretan margin. Consequently, topographically confined sedimentary units have been deposited south of Crete in the last 12 Ma, including turbidites and other mass-flow deposits fed by evolving transverse and axial channel systems. Surface processes controlling facies distribution include the direct inflow of sediment from alluvial-fan systems and incising mountain rivers onto the Cretan slope, where significant sediment instability processes occur at present. In this setting, seismic profiles reveal eight different types of stratigraphic contacts on basin-margin highs, and basinal areas show evidence of halokinesis and/or fluid escape. The acquired data also show that significant changes to the margin’s configuration occurred in association with the post-Alpine tectonic and eustatic episodes affecting the Eastern Mediterranean.     

A Pull-Up Shallow Water Seismometer

An inexpensive Pull-Up Shallow Water Seismometer (PUSS) has been designed and built to conduct long range seismic refraction experiments in the North Sea and the continental shelf around Britain, with the particular goal of studying the crustal and lithospheric structure under the epeirogenic basin of the North Sea. Signals from a gimbal-mounted 3-component geophone and a hydrophone are frequency modulated and mixed with clock and flutter correction signals before being recorded on a standard speed cassette tape recorder, with one hour of recording time. A 100 hour programmable timer allows the interval between the time of reset of the clock and each shot window of optional 5 or 10 min duration, to be preselected. The PUSS is launched and recovered using a pull-up technique originally developed for current meters. The replay system is also described.In May 1976 sea trials of 5 PUSSes were conducted along a 200 km refraction line in the North Sea. The encouraging performance of the equipment resulted in the decision to build a further 10 units and to proceed with a 400 km refraction line planned for the summer of 1977.     

A clay mineral investigation of six cores from the Gulf of Mexico

Samples were studied from each color change along six gravity cores from nearshore to deep-sea areas in the Gulf of Mexico. Analytical methods and techniques used to characterize the sediments were X-ray diffraction, differential thermal analysis, cation exchange capacity, particle size distribution and fractionation of the clay-size material with the supercentrifuge.     

On the recovery of surface wave by pressure transfer function

Except the commonly selected pressure transfer function derived from the linear wave theory, a previous study on the pressure transfer function for recovering surface wave from underwater pressure transducer suggested that the pressure transfer function is a function of frequency parameter only. With careful analysis, this study showed that the pressure transfer function should include a transducer submergence parameter as that given by the linear theory. It was found that the previously suggested empirical formula should be restricted to measurements with the pressure transducer close to the surface; otherwise overestimation of wave height would result. Field measurements were carried out with an acoustic wave gauge and a synchronized pressure transducer located at various depths with submergence parameter close to 1 (near the sea floor). It was shown that the previous one-parameter empirical formula might overestimate the significant wave height by more than 30%. This study found that with deep-water wave bursts excluded, the transfer function based on the linear wave theory provided a fairly good estimation on the significant wave heights, with an average deviation of 3.6%.