跨海长桥风致行车安全研究

基于风作用下车辆模型行驶极限状态分析获得了相应的安全行驶临界风速,应用概率统计方法建立了桥位风速统计和极值风速概率分布模型,桥面风环境测速风洞试验给出了自然风与桥面行车风环境的关系,进而评估了自然风作用下车辆不同车速条件下的桥面行驶安全性。采用上述评估方法针对杭州湾跨海大桥的研究,表明了风障措施提高桥面行车安全的有效性。     

深圳湾大桥结构健康及安全监控预警系统硬件概述

通过对已完成实施的深港西部通道深圳湾公路大桥结构健康及安全监控预警系统 (SZBHMS)的介绍,综合阐述了研发系统的构建与硬件内容.在系统中选用了基于美国NI公司虚拟仪器技术的数据采集设备硬件和基础软件产品,并采用了GPS技术时钟授时接收机等技术.结果表明:系统能够协调运行,实现了预期设计功能,保证了SZWBHMS系统长期运行的高可靠性、实时性以及技术的先进性.     

台州湾海域水文泥沙环境及海床冲淤演变分析

文章结合台州湾海域历史上各年代、各测次的水文泥沙测验和实测地形资料,对该海区1934~1998年和1988~2003年2个不同时间长度内的地形变化进行了分析,结果表明:台州湾属于强潮海域,具有潮差大、潮汐动力强的特点;该海区在1988年以前处于略有淤积状态,而1988年后期处于冲淤基本平衡的稳定状况;椒江口内高含沙水体的往返运移对湾内水域冲淤变化的影响甚小;造成该海区海床变化的泥沙主要来自于浙江东海岸沿岸泥沙运动,随着来自长江口泥沙的逐年减少,该海域的海床形态基本趋于稳定,海域含沙量逐步降低,为台州市深水港的建设提供了良好的泥沙环境。     

北部湾港口建设与整合的思考

2009年4月,交通运输部批准了防城港、钦州港和北海三港统一归并,组成"广西北部湾港"。这标志着我国沿海又一个港口群的诞生。阐述了北部湾港口的建设与整合的目标和进展情况。分析了北部湾港口建设与整合对促进北部湾地区经济发展的重大意义。最后,提出了进一步健全北部湾港口管理体制、发展临港工业等5项对策。     

Changes in size at maturity of European hake Atlantic populations in relation with stock structure and environmental regimes

European hake (Merluccius merluccius) female size at maturity is estimated on an annual basis for Bay of Biscay and Galician coast, which are parts of the distribution of the Northern and Southern stocks, respectively. Clear trends in this reproductive parameter are observed along the time series and the potential factors affecting these trends have been investigated. Total biomass, different indexes of SSB, age diversity index, fishing mortality at age, NAO winter index, upwelling index and temperature were included in multiple regressions models to assess the relative importance of each of them on shifts in size at maturity.Bay of Biscay and Galician coast hake have followed different evolution in patterns of changes in size at maturity. In Bay of Biscay, a steadily decline of 15 cm has been observed from 1987 to 2004, which is well predicted by fishing mortality and age diversity, but also the environment may have played an important role. However, on the Galician coast a drastic decline of 16 cm from 1980 to 1988 was followed by a rapid increase in size at maturity during the next 10 years to original values and a stable period in the last 6 years. Decreasing biomass may explain the decline in size at maturity in the first period. However, total biomass and spawning biomass declined even during the period when size at maturity increased, which is contrary to compensatory theory. Shifts in environmental regime, NAO and upwelling, may have contributed to a decelerated growth during this period that might explain the later maturation.     

渤海湾底质重金属污染及其潜在生态风险评价

基于渤海湾22个监测点3年的监测数据,应用Hakanson潜在生态风险指数法,分析了渤海湾天津段表层沉积物中5种重金属的含量与分布,并进行生态风险评价。结果表明:渤海湾为轻微生态危害,其中镉的污染程度最大,锌的污染程度最小,5种重金属危害系数顺序为:Cd>Hg>Pb>Cu>Zn。     

港珠澳大桥工程二维潮流数学模型研究

文章建立了基于无结构网格的港珠澳大桥所在海区平面二维潮流数学模型,并采用潮流数值模拟手段对该海区的潮流动力进行了模拟研究,分析了大桥工程周围海域的潮流动力影响。为了在宽广海域中刻画桥墩的阻水影响,将桥墩概化为陆地,并采用桩基阻力处理方法处理桥墩阻力。通过研究采用了局部网格加密方法,桥墩处最小网格长度仅2.39m。研究结果表明:港珠澳大桥的建设对伶仃洋潮流的影响甚微。若以流速变化0.01m/s作为有显著影响的判断标准,则工程对潮流的影响仅限于内伶仃岛与桂山岛之间的大桥及人工岛附近。大量的研究结果可为论证港珠澳大桥建设方案的可行性提供理论依据。     

Navigating Institutional Constraints in the Process of Computational Environmental Modeling

Abstract

The use of computational models has proliferated in the last few decades due to the practical benefits that they offer in terms of understanding complex systems. However, the process of developing a computational model is not only shaped by scientific and practical concerns. Modelers must also navigate the institutional structures in which the models are constructed and implemented. In the process, they must often draw upon existing or create new social relationships that can, themselves, alter the institutional structures they are attempting to navigate. In this article, I use an ethnographic approach to examine three examples in which the process of building and implementing a computational model was constrained by institutional factors and the strategies the modelers used to navigate them. The research was conducted with computational modelers at the Chesapeake Bay Program who are involved in constructing the Chesapeake Bay modeling system for nutrient management in the watershed. Modelers in this context had to: build relationships with the broader scientific community to reinforce the “believability” of the model, draw upon institutional relationships in order to work around limitations on data-sharing between organizations, and manage differing incentive structures to motivate and coordinate the research needed to complete the model     

Atmospheric CO2 measurements and error analysis on seasonal air–sea CO2 fluxes in the Bay of Biscay

Atmospheric molar fraction of CO₂ (xCO₂^atm) measurements obtained on board of ships of opportunity are used to parameterize the seasonal cycle of atmospheric xCO₂ (xCO₂^atm) in three regions of the eastern North Atlantic (Galician and French offshore and Bay of Biscay). Three selection criteria are established to eliminate spurious values and identify xCO₂^atm data representative of atmospheric background values. The filtered data set is fitted to seasonal curve, consisting of an annual trend plus a seasonal cycle. Although the fitted curves are consistent with the seasonal evolution of xCO₂^atm data series from land meteorological stations, only ship-board measurements can report the presence of winter xCO₂^atm minimum on Bay of Biscay. Weekly air–sea CO₂ flux differences (mmol C·m^− 2 day^− 1) produced by the several options of xCO₂^atm usually used (ship-board measurements, data from land meteorological stations and annually averaged values) were calculated in Bay of Biscay throughout 2003. Flux error using fitted seasonal curve relative to on board measurements was minimal, whereas land stations and annual means yielded random (− 0.2 ± 0.3 mmol C·m^− 2·day^− 1) and systematic (− 0.1 ± 0.4 mmol C·m^− 2 day^− 1), respectively. The effect of different available sources of sea level pressure, wind speed and transfer velocity were also evaluated. Wind speed and transfer velocity parameters are found as the most critical choice in the estimate of CO₂ fluxes reaching a flux uncertainty of 7 mmol C·m^− 2·day^− 1 during springtime. The atmospheric pressure shows a notable relative effect during summertime although its influence is quantitatively slight on annual scale (0.3 ± 0.2 mmol C·m^− 2·day^− 1). All results confirms the role of the Bay of Biscay as CO₂ sink for the 2003 with an annual mean CO₂ flux around − 5 ± 5 mmol C m^− 2 day^− 1.     

杭州湾跨海大桥船舶碰撞风险分析

文中主要对引航锚地海域船桥碰撞风险进行分析,合理识别风险因素,并运用故障树分析法对风险因素进行评估,最后提出风险控制的措施。