Effect of Band Width on Fatigue Life under Random Stress Response

A fatigue life estimation method for offshore structures under random stress response is studied in this paper. The method of broad band cumulative frequency number is used to determine the effect of band width of stress frequency spectra on fatigue. A formula of correction factor for fatigue under broad band stress spectra is suggested and compared with that given by P. H. Wirsching.     

A First Generation Stochastic Bioeconomic Analysis of Algal Bloom Control in a Coastal Lagoon (Sacca di Goro, Po River Delta)

Abstract. In this work we have developed a very simple stochastic mathematical model of Ulva spp. growth to quantitatively evaluate the economic costs of algal harvesting and the related benefits in terms of avoided'economic loss'of clam production due to an effective prevention of algal blooms and the consequent anoxic crises. Algal growth was simulated by means of a discrete time difference equation of Ulva biomass where the finite growth rate depends only upon water temperature. In order to explicitly include environmental variability, a seasonal autoregressive model calibrated on available data was used to simulate water temperature. Different harvesting scenarios were analysed in terms of the number of harvesting vessels employed and the threshold biomass of Ulva at which vessels start to operate. Costs of algal harvesting and disposal, as well as monetary damages resulting from the collapse of clam production as a consequence of algal blooms, were assessed by interviewing the managers of the Clam Fishermen's Union of Goro. A Monte Carlo approach was used to estimate the mean and total statistical distribution of costs and benefits of different harvesting strategies. Our analysis shows that the most cost-effective management policy is attained with 4–6 vessels operating at low algal density able to harvest as much Ulva as possible with intensive and short interventions at the beginning of the seasonal growth.     

Genotoxic impacts in Klaip da Marine port and B ting oil terminal areas (Baltic Sea)

Genotoxic effects were evaluated in the somatic and gonadal cells of bivalve and gastropod molluscs inhabiting different sites of Klaip da port area in Lithuania. The occurrence of aneuploidy and polyploidy of cells, meiotic injures, centromere dissociation and fragmented polyploid nuclei as cytogenetic indicators of environmental stressors was assessed in snails Lymnaea ovata . The highest level of environmental genotoxicity (in 43.2 and 46.2% of studied cells) was observed in the tissues of snails inhabiting Malk Bay in 1995 and 1996. Dredging and thus removal of contaminated sediments from Malk Bay resulted in significant decrease (up to 27.2% in 1999) of cytogenetic injures in molluscs studied over the period from 1997 to 1999. However, the frequency of cytogenetic disturbances in molluscs from Vilhelmo Channel was increasing (1.8 times) from 1995 to 1999. Therefore, the ecological safety of the biggest drinking water supply for Klaip da population became questionable. Assessment of cytogenetic damage in Mytilus edulis (MN test) and the crustacean, Balanus improvisus, (aneugenic effects) inhabiting the Baltic Sea at B ting oil terminal has shown the highest genotoxicity level in the zone of sewage effluents from Palanga town and Ma eikiai oil refinery plant. Extensive cytogenetic injuries in gonadal cells indicated the potential long-term hazards of pollutants to ecological health and integrity of aquatic species.     

镉致鲫(Carassius auratus)外周血单个核细胞DNA损伤与增殖抑制

采用体内注射染镉的方法进行镉诱导鲫外周血单个核细胞(PBMC)DNA损伤与增殖抑制相关性的研究。将鲫(400g／尾)驯养4周后进行随机分组，每组5尾，以Cdh浓度1．25、2．50和3．75mg／kg腹腔注射染鲫，以生理盐水腹腔注射鲫为对照，染镉后0、3、5、7、10和14天取无菌抗凝鲫血，经淋巴细胞分离液离心分离获取PBMC，用单细胞凝胶电泳法检测PBMC的DNA损伤，用^3H-胸腺嘧啶脱氧核苷掺入法检测PBMC的增殖。结果表明，3天时各染镉组DNA迁移度增加，5天时继续加大并于7天时达到峰值，10天和14天时呈现逐渐减小的趋势。1．25mg／kg组与对照组在不同时间放射性活度(咖m)的差异均无显著性；0天和3天时各染镉组与对照组咖m的差异均无显著性；5天时2．50和3．75mg／kg组dpm明显下降，7天和10天时dpm与5天时基本相同，14天时dpm呈上升趋势。镉诱导DNA损伤与其抑制PBMC增殖相比，作用时间短且浓度低，初步推测镉诱导的DNA损伤是镉抑制PBMC增殖的重要机制之一。     

Strength modelling in stiffened FRP structures with viscoelastic inserts for ocean structures

The purpose of this paper is to investigate the static structural response of a new type of composite stiffener containing a viscoelastic insert. The introduction of this material has proven benefits in terms of noise and vibration attenuation across the joint. House, 1997 describes the use of this material in sonar dome/hull connections — equipment sensitive to noise and vibration. Structural stiffeners incorporating this material would have positive implications for not only marine and ocean structures but for structural applications in general. The effects of introducing this new material on the structural response of the joint are numerically examined by using a progressive damage model. Application of this method allows the initiation and progression of failure and ultimate failure load to be predicted. Experimental results show good qualitative and quantitative agreement with the predictive damage model.     

基于信息熵的溢油对天然渔业可持续承载力损害的评估

作者基于信息熵理论,以溢油事故对海洋天然渔业损害为切入点探讨海洋生态系统可持续承载力损害评估方法。论文从生态系统状态、功能、污染、修复等4个方面构建了熵流和熵产生指标体系,以"塔斯曼海"轮溢油事故为例进行计算和评估,结果表明:溢油使海洋生态系统的价值产出能力下降94.7%、总的承载力下降194.9%,溢油治理的效果小于溢油对生态承载力的损害。本评价是现有溢油生态损害评价的补充,可为长期生态损害评估、生态修复和环境管理决策提供科学依据。     

Assessing DNA damage in cnidarians using the Comet assay

The assessment of DNA damage by the Comet assay has been described as a useful non-specific general biomarker of stress in many marine organisms. In field situations it has successfully been employed to distinguish between reference and polluted sites and in the laboratory it has been widely used as a mechanistic tool to determine pollutant effects and mechanisms of DNA damage. To date a wide range of marine vertebrates and invertebrates have been used, however, the usefulness of this assay as a biomarker in cnidarians has not yet been assessed. The aims of this study were to optimize the Comet assay for cnidarian cells and to assess its utility for detecting genotoxic damage in these cells. Cells were isolated from the North American pacific coast temperate sea anemone Anthopleura elegantissima using a non-enzymatic dissociation procedure and viability was determined to be in excess of 90%. Cells were incubated either with (1 h acute exposures) hydrogen peroxide (H(2)O(2)), ethylmethanesulphonate (EMS) or benzo(a)pyrene (B[a]P). In comparison to other marine species, anemone cells exhibited high control or background levels of DNA strand breaks. Despite this, however, we observed dose responses for each of the study chemicals with no reduction in cell viability. This study demonstrates that anemone cells respond to known DNA damaging agents, including B[a]P which requires metabolism to exert its genotoxic effect, and that the Comet assay may prove to be a useful biomarker of stress in cnidarian species.     

1556年陕西华县大地震形变遗迹及华山山前断裂古地震研究

华山山前断裂带晚第四纪以来具有明显的新活动,沿断裂带及其两侧分布有最新断层崖,基岩裂缝、黄土裂缝、山体崩(滑)塌体等众多的地震形变和破坏遗迹,华山山前断裂带应是1556年华县8级地震的发震断层。 从本文提供的一个古地震剖面分析,华山山前断裂带全新世以来可能发生过四次大地震,其重复间隔约2000—2500年     

Integration of a continuum damage model for shale with the cutting plane algorithm

The stability of integration is essential to numerical simulations especially when solving nonlinear problems. In this work, a continuum damage mechanics model proposed by the first author is implemented with an integration method named cutting plane algorithm (CPA) to improve the robustness of the simulation. This integration method is one type of return mapping algorithm that bypasses the need for computing the gradients. We compare the current integration method with the previous direct method, and the result shows that the cutting plane algorithm exhibits excellent performance under large loading rate conditions. To enhance accuracy of the new method, a control procedure is utilized in the implementation of the algorithm based on error analysis. Thereafter, the theory of poromechanics is utilized with the damage model to account for the effects of fluid diffusion. Laboratory tests simulated with finite element method illustrate distinct behaviors of shale with different loading rates and indicate the development of microcrack propagation under triaxial compression. Copyright © 2016 John Wiley & Sons, Ltd.