Assessment of the effects of a port expansion on algae appearance in a costal bay through mathematical modelling. Application to San Lorenzo Bay (North Spain)

In the last years several episodes of algae appearance affecting bathing areas have been observed in San Lorenzo Bay (north of Spain). The analysis of the collected algae revealed that they might come from near intertidal or shallow subtidal zones due to eutrophication processes or through drift algae movement by the action of marine currents. In the vicinity of this area, the expansion of the Port of Gijón (now under construction) supposes a significant modification of the coastal geometry. The magnitude of such an expansion could cause changes in the patterns of currents in the bay, with the consequent alteration of the observed algal appearance phenomena. A mathematical modelling study to evaluate the risk of generation of eutrophication processes in the San Lorenzo Bay area and the transport of drift algae from near sea bed areas was developed. This study required the use of different hydrodynamic models in order to characterize the currents caused by tides, winds and waves. The eutrophication processes in the bay were analyzed with a depth-averaged two-dimensional eutrophication model which deals with eight water quality variables. Calibration of model parameters with the observed data from a field survey was performed. A reasonable agreement with the field measurements was achieved. Model results showed that the maximum phytoplankton concentrations were below eutrophic conditions. Although, the port expansion has led to an increment of phytoplankton concentrations, chlorophyll a levels were not representative of eutrophic conditions. To analyse the transport of drift algae, a methodology based on the utilization of a two-dimensional model which solves the depth-averaged advection-diffusion equation considering seaweed as a conservative tracer was developed and applied. Numerical modelling allowed the identification of the coastal areas that seems to be the source of the seaweed found on the beach. It was also proven that port expansion does not significantly affect drift algae transport in the area.     

Ports’ service attributes for ship navigation safety

The purpose of this paper is to discuss the service attributes of ports for ship navigation safety. Based on the relevant literature and the features of ship navigation in ports, the service attributes of ports for ship navigation were first investigated. A fuzzy AHP model was then used to identify those attributes from shipmasters’ perspectives. Finally, a Dissatisfaction Attitude (DA) index was used to determine the attributes’ priorities, by which the port authorities may make policies for improving ship navigation safety. As an empirical study, the shipmasters berthing their ships in Kaohsiung Port were surveyed to validate the model. The result constructs 19 port service attributes (SAs) for ship navigation safety, in which, the shipmasters place more emphasis on the SAs of operators’ professional literacy, including the marine pilot’s professional and English communication abilities, the VTC (Vessel Traffic Center) regulator’s professional and English communication abilities, and the tugboat driver’s skills. While, for Kaohsiung Port, currently, the traffic control of fairway is the most important aspect to be improved. The theoretical and managerial implications of the findings for port authorities in improving ship navigation safety are discussed.     

Structuring cooperative behavior under the National Environmental Policy Act of the United States

A trend is presently under way to streamline the compliance requirements of the National Environmental Policy Act of the United States through cooperative assessment procedures. Since the law was enacted in 1970, however, participants in the assessment process have tended to settle disagreements by adversarial rather than cooperative means. This study focuses on a highly acclaimed environmental assessment procedure undertaken by the U.S. Steel Corporation for its proposed $4.0 billion Lakefront Steel Plant. Survey research data were gathered to measure the underlying management philosophy perceived by interorganizational representatives, who attended a series of Technical Team meetings designed to coordinate the assessment effort and to open communication channels. A social psychological scale of behavioral dimensions was adapted from Likert to define the composition and the extent of cooperation at these meetings. A newly constructed scale was used to measure the quantity and quality of representation by each of the major organizations involved. Informal interviews were conducted with project participants to obtain further insight into member interaction. Results indicate that democratic problem solving was in evidence but also suggest a preference by respondents for improved procedures. The paper outlines areas of concern voiced by respondents and offers the means for improving the operating procedures of similar interorganizational environmental assessments.     

天津港环境风险防范及管理对策研究

分析了天津港主要的环境风险类型.并重点分析了天津港溢油事故风险、陆域储运事故风险、港口及其附近海域赤潮风险的发生原因及趋势.针对港口环境风险事故的成因提出了相应的防范对策议,并在此基础上建立了天津港环境风险应急响应程序和风险事故应急决策支持系统.最后,结合环境风险防范及应急体系中存在的障碍和天津港未来的发展趋势,提出了提高天津港突发性环境事件应急水平的建议,并可为其他港口所借鉴.     

塔克什肯口岸土壤放射核素含量调查研究

利用高分辨半导体能谱分析方法分析了新疆塔克什肯口岸土壤天然放射性核素铀238、镭226、钍232、钾40和人工放射性核素铯137的含量,共选取8个采样点16个土壤样品及4个煤炭及废旧金属样点。结果表明:进口货物道路各采样点其铀238、钾40及铯137均比非进口货物道路各点高,镭226、钍232含量则相反,而煤炭和废金属的各样品的铀238、镭226、钍232、钾40都高于进出口道路和非进口道路,Cs137则相反,表明进口煤炭和非金属对天然放射性核素产生了较大影响,而对人工放射性核素影响较小。和新疆及全国背景值比,进口道路和非进口道路土壤中各放射性核素含量均未超过天然本底值范围,进口煤炭和废金属虽然各放射性核素含量则略高于背景值,表明试验点没有受到放射性污染,对当地居民和进出境人员不会产生辐射伤害。     

汕头港污染扩散计算研究

广东汕头高新技术产业园区西区向汕头牛田洋排放污水,为科学评价污水排放的影响,需进行污染扩散计算.根据牛田洋肚大口小的地形特点和排污方案论证计算的需要,本模型采用正交曲线网格,网格既能贴牛田洋弯曲边界,又能克服计算域网格疏密悬殊的问题.该污染扩散模型,通过验证计算,最大潮位误差0.06m,潮位、流速过程与实测基本一致,模型采用的糙率对牛田洋是适宜的,建立的污染扩散数学模型较真实地模拟了牛田洋附近水域的水流情况和污染扩散仿规律.     

Optimization and evaluation of steel industry’s water-use system

In the steel industry, water is mainly used for cleaning and cooling. All these different tasks produce wastewaters that differ not only in quantity but also in quality. This study integrates all water-use processes into a system and applies substance flow analysis to build up an optimization model and an evaluation index system for the water-use network of a steel enterprise. Based on the index system, water-use status of large steel enterprises in China is evaluated and problems in the present water consumption are identified. A contrast analysis between present and optimized water-use is conducted, which then serves as the basis for the network optimization and countermeasure articulation. Finally, an analysis has been made on one of the most important and largest steel enterprise in China. The results indicate that after optimization fresh water consumption can be decreased by 11.1% and wastewater discharge can be decreased by 94.54%.     

Plastic buckling,wrinkling and collapse behaviour of dented X80 steel line pipes under axial compression

High strength steel pipes have found increasing applications in deep high pressure offshore oil/gas lines. Damages in the form of dent are among common causes of pipeline failure. Indentation, plastic buckling and residual strength of dented normal grade steel pipes under bending, axial and combined loading have previously been addressed by a number of researchers. The plastic buckling and collapse of dented high grades steel line pipes, however, have received less previous attentions.In the current study an experimental model testing was used to evaluate the residual strength of dented X80 steel pipes under monotonic axial compression. The tubular specimens were first laterally dented by an indentor while resting on a saddle shape support. The specimens were then examined under axial compression to study the dent effects on their collapse behaviour. Numerical simulations were also used to analyse the effect of the indentor ratio, shape and alignment on the residual strength of dented steel tubes under monotonic axial compression. The results from the current study on high strength steels were also compared with semi-empirical equations available in the literature for low strength steels. It was found that these equations provide reasonable predictions for the axial residual capacity of the high strength steel pipes when the dent depths are small. With deep dents, however, they considerably underestimate the axial residual capacity of the high strength steel pipes.     

Steel slag carbonation in a flow-through reactor system: The role of fluid-flux

Steel production is currently the largest industrial source of atmospheric CO₂. As annual steel production continues to grow, the need for effective methods of reducing its carbon footprint increases correspondingly. The carbonation of the calcium-bearing phases in steel slag generated during basic oxygen furnace (BOF) steel production, in particular its major constituent, larnite {Ca₂SiO₄}, which is a structural analogue of olivine {(MgFe)₂SiO₄}, the main mineral subjected to natural carbonation in peridotites, offers the potential to offset some of these emissions. However, the controls on the nature and efficiency of steel slag carbonation are yet to be completely understood. Experiments were conducted exposing steel slag grains to a CO₂-H₂O mixture in both batch and flow-through reactors to investigate the impact of temperature, fluid flux, and reaction gradient on the dissolution and carbonation of steel slag. The results of these experiments show that dissolution and carbonation of BOF steel slag are more efficient in a flow-through reactor than in the batch reactors used in most previous studies. Moreover, they show that fluid flux needs to be optimized in addition to grain size, pressure, and temperature, in order to maximize the efficiency of carbonation. Based on these results, a two-stage reactor consisting of a high and a low fluid-flux chamber is proposed for CO₂ sequestration by steel slag carbonation, allowing dissolution of the slag and precipitation of calcium carbonate to occur within a single flow-through system.     

Seismic risk assessment of liquid overtopping in a steel storage tank equipped with a single deck floating roof

Major earthquakes have demonstrated that Natech events can be triggered by liquid overtopping in liquid storage tanks equipped with floating roofs. Thus, research on the dynamic behaviour of steel storage tanks with floating roofs is still required. In this paper, the seismic risk against liquid overtopping in a real steel storage tank with a floating roof was analysed using a simplified model that was validated by a refined finite element model based on the arbitrary Lagrangian-Eulerian approach. The simplified model utilizes the Lagrangian of a floating roof-fluid system and is capable of providing a response history of the floating roof. It was demonstrated that it could predict the maximum vertical displacement very accurately, while some differences were observed in the response history of vertical displacement. The computational time for a single response history analysis based on the simplified model amounted to a few minutes, which is significantly less demanding compared to hours required for response history analysis in the case of the refined FE model. The simplified model is thus appropriate for the seismic fragility analysis considering the overtopping limit state. It is shown that the fragility curves are significantly affected by the liquid filling level. The risk for liquid overtopping is quite high in the case of a full tank. However, by considering the variation of filling level during the year, the overtopping risk was observed reduced by approximately 30%. Alternatively, the approximate fragility analysis for the liquid overtopping can be performed by utilizing the Eurocode formula for the vertical displacement of liquid. This approach is straightforward, but the formula does not account for the higher mode effects, which may result in overestimated seismic intensity causing overtopping, as discussed in the paper.