Fuzzy Risk Analysis of Harbour Engineering Investment by Hierarchy System Approach     

Lin Shaopei  Zhang Zhongming Professor  Civil  Architectural Engineering Dept.  Shanghai Jiao Tong University  Shanghai Lecturer  Civil  Architectural Engineering Dept.  Shanghai Jiao Tong University  Shanghai 《中国海洋工程》1992,(1)

The present risk analysis model of engineering investment is built by fuzzy hierarchy approach under the assumption of maximizing the revenues of the project during its whole life cycle of operation. It can reasonably be expressed by a system evaluation analysis. As a matter of fact, the system, aimed by its system goal can be modelled by a set of factors, constitutively structured by certain links between them, to form a factorial network chart, which represents the essentials of the system behaviours, the nodes of which represent the factors concerned. The weight distribution between factors located at the same level can be determined by the eigen-value problem of a "pair comparison" relation matrix. The weight distribution of factors at each level is successively manipulated until the fuzzy synthetic risk assessment. As an example of risk analysis of engineering investment, a harbour construction project is presented for illustration.  相似文献   

提高南四湖综合治理工程的投资效益     

张方钵 《海洋湖沼通报》1992,(1):34-36

南四湖治理的中心任务是降低洪水位,在尽快续建两项主要工程—扩大韩庄运河和扩大湖腰—的前提下,湖内清障是保证洪水畅泄、降低水位、缩短滞洪时间,减少洪灾损失的重要措施。本文着重对以往湖内清苇实施困难、效果不佳的原因进行了分析,为了提高今后治湖工程的综合经济效益,对开展清障工作提出了建议。  相似文献   

A discussion on typhoon occurred in the Haikou Bay and impact mechanism on seawater quality     

Chen Chunhu  Li Qiaoxiang 《海洋学报(英文版)》2001,20(3):355-362

INTRODUIONThe Haikou Bay is an imPOrtant hay in Hainan Pmeince. Investigatnin of water qualitywas carried out three times every y6ar to understand the vatying trend of water quality fOr tak-ing pmpr countereres. betimes we may ee comParison conclustons of poIluting degreein Water Quality Monitoring Bulletin Of HaikOu Bay. But the comParison conclusbo is notreareable because the ocean is a complicated system with the interaction of wind, current,wave, tide, biolOgy, chemistry and so …  相似文献   

中国内蒙古白云鄂博Fe-Nb-REE矿床地质特征与陨石撞击成因   总被引：3，自引：0，他引：3  

姚德  张丽洁  ＷｉｌｔｓｈｉｒｅＪ  ＭａｌａｈｏｆｆＡ  业渝光 《海洋地质与第四纪地质》1998,(4)

中国内蒙古白云鄂博Ｆｅ－Ｎｂ－ＲＥＥ矿床由于其独特的矿床地质与矿物地球化学特征而明显有别于世界上其它绝大多数的Ｆｅ、Ｎｂ、ＲＥＥ矿床。本文提出该矿床是约１５００Ｍａ前一块富含ＲＥＥ、Ｎｂ的铁陨石撞击在华北地台北缘碳酸盐沉积陆架上形成的。现在矿床矿体中心的块状铁矿石更多地代表了陨石的成分,矿体外侧富含ＲＥＥ、Ｎｂ的环状白云岩是陨石撞击浅海碳酸盐沉积陆架释放的巨大能量使海水（含Ｍｇ）迅速受热溶解陨石中的ＲＥＥ、Ｎｂ等形成的含金属热液蚀变沉积成因方解石质碳酸盐沉积物的结果。块状铁矿石和环状白云岩之间矿物成分异常复杂、结晶颗粒十分细小的条带状、侵染状Ｆｅ－Ｎｂ－ＲＥＥ矿石组成的矿体则是撞击瞬间导致的由陨石（Ｆｅ、Ｎｂ、ＲＥＥ）、海水（Ｍｇ、Ｎａ、Ｋ等）和碳酸盐（含少量硅质夹层）（Ｃａ、Ｓｉ、Ａｌ等）组成的超高温、多组分、富水体系在快速冷却条件下反应生成的产物。撞击释放的巨大热能,在撞击体（陨石）下部相对不易释放,导致部分碳酸盐沉积物在富含ＲＥＥ、Ｎｂ、Ｍｇ等的热液参与下融熔,然后侵入到周围岩石裂隙形成矿区内众多的富含ＲＥＥ、Ｎｂ的白云岩脉。撞击的瞬间导致大量岩石、矿物碎屑、海水、蒸汽弥漫天空,同时引发巨大的海啸,然  相似文献   

Model Simulations of Carbon Sequestration in the Northwest Pacific by Direct Injection     

Katsumi?MatsumotoEmail author  Bryan?K.?Mignone 《Journal of Oceanography》2005,61(4):747-760

The direct disposal of CO₂ into the ocean interior represents a possible means to help mitigate rising levels of atmospheric CO₂. Here, we use three different versions of an ocean general circulation model (OGCM) to simulate the direct injection of liquid CO₂ near Tokyo. Our results confirm that direct injection can sequester large amounts of CO₂ from the atmosphere when disposal is made at sufficient depth (80–100% of the carbon injected at 3000 m remains in the ocean after 500 years) but show that the calculated efficiency is rather sensitive to the choice of physical model. Moreover, we show, for the first time in an OGCM and under a reasonable set of economic assumptions, that sequestration effectiveness is quite high for even shallow injections. However, the severe acidification that accompanies injection and the impossibility of effectively monitoring injected plumes argue against the large-scale viability of this technology. Our coarse-grid models show that injection at the rate of 0.1 Pg-C/yr lowers pH near the site of injection by as much as 0.7–1.0 pH-unit. Such pH anomalies would be much larger in more finely gridded models (and in reality) and have potential to severely harm deep-sea organisms. We also show that, after several hundred years, one would effectively need to survey the entire ocean in order to accurately verify the inventory of injected carbon. These results suggest that while retention may be sufficient to justify disposal costs, other practical problems will limit or at best delay widespread deployment of this technology.  相似文献   

Recovery of the seabed following marine aggregate dredging on the Hastings Shingle Bank off the southeast coast of England     

Keith Cooper  Sian Boyd  Jacqueline Eggleton  David Limpenny  Hubert Rees  Koen Vanstaen 《Estuarine, Coastal and Shelf Science》2007,75(4):547-558

The aim of this study was to investigate the effect of dredging intensity on the physical and biological recovery times of the seabed following marine aggregate dredging. Two areas of seabed, previously subject to, respectively, relatively high and lower levels of dredging intensity, were identified on the Hastings Shingle Bank. Two reference areas were also selected for comparative purposes. All four sites were monitored annually over the period 2001–2004, using a combination of acoustic, video and grab sampling techniques. Since the site was last dredged in 1996, this was intended to provide a sequence of data 5–8 years after cessation of dredging. However, an unexpected resumption of dredging within the high intensity site, during 2002 and 2003, allowed an additional assessment of the immediate effects and aftermath of renewed dredging at the seabed. The early stages of recovery could then be assessed after dredging ceased in 2003. Results from both dredged sites provide a useful insight into the early and latter stages of physical and biological recovery. A comparison of recent and historic dredge track features provided evidence of track erosion. However, tracks were still visible 8 years after the cessation of dredging. Within the high dredging intensity site, recolonisation was relatively rapid after the cessation of dredging in 2003. Rather than indicating a full recovery, we suggest that this initial ‘colonization community’ may enter a transition phase before eventually reaching equilibrium. This hypothesis is supported by results from the low intensity site, where biological recovery was judged to have taken 7 years. Further monitoring is needed in order to test this. An alternative explanation is that the rapid recovery may be explained by the settlement of large numbers of Sabellaria spinulosa. As the resumption of dredging within the high intensity site limited our assessment of longer-term recovery it is not yet possible to assume that a 7-year biological recovery period will be applicable to other, more intensively dredged areas at this or more distant locations.  相似文献   

An assessment model for the fate and environmental effects of offshore drilling mud discharges   总被引：1，自引：0，他引：1  

Charles G. Hannah  Adam Drozdowski  John Loder  Kee Muschenheim  Tim Milligan 《Estuarine, Coastal and Shelf Science》2006,70(4):577

The benthic boundary layer transport (bblt) model was developed to assess potential impact zones from drilling mud discharges from offshore oil and gas drilling. The model focuses on the drift, dispersion and concentration levels of the suspended fraction of the drilling mud fines in the benthic boundary layer with the assumption of a spatially homogeneous environment. The current version of the model includes a wave boundary layer, a breakup module for drilling mud flocs, a dose–response module for scallops, and a graphical user interface (GUI). The GUI was written in Java which makes the code largely platform independent. Simulations of suspended barite concentration near Sable Island on the Scotian Shelf during drilling in the fall of 1999 reproduce the very low concentrations (generally less than 1 μg L⁻¹) observed during the Environmental Effects Monitoring program. However, the simulations also exhibited concentrations in excess of the no-effects concentration for scallops (100 μg L⁻¹) prior to the sampling program. The model estimates that the potential impact on scallops in the vicinity of the drilling is a few days of lost growth over scales of a few kilometers.  相似文献   

Citation Impacts of AAG Presidential Addresses     

Stanley D. Brunn 《The Professional geographer》2018,70(2):209-218

The American Association of Geographers (AAG) president's annual address is considered an important statement about how she or he views the state of the discipline or one's research specialties. Building on previous studies on journal and individual impacts, this study measures the impacts of addresses using Google Scholar data and the Web of Science score. Using these data I classify the addresses into three distinct categories: alpha, beta, and gamma. The results reveal wide and substantial differences in Scholar ratings and Web of Science scores. A few have very high ratings, but many more are in the gamma category. Addresses by women and men presidents that promote new fields of study, extend geographic research to interdisciplinary audiences, and encourage the topics and frameworks of existing fields have higher ratings than those that appeal to more specialized audiences.  相似文献   

Human activity was a major driver of the mid‐Holocene vegetation change in southern Cumbria: implications for the elm decline in the British Isles     

《第四纪科学杂志》2017,32(7):934-945

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Geochemical and isotopic signatures of Archaean to Palaeoproterozoic extraterrestrial impact ejecta/fallout units     

A. Y. Glikson 《Australian Journal of Earth Sciences》2013,60(4-5):785-798

Criteria allowing diagnostic identification of asteroid and comet impact fallout units (impactites), including fragmental ejecta, microtektites and microkrystite spherules (impact vapour condensates) comprise: (i) unique mineral fallout phases—shocked quartz grains, coesite and nano-diamonds; (ii) unique intra-microkrystite phases—Ni-chromite, Ni-nanonuggets and Ir-nanonuggets, condensed from vapour enriched in meteoritic components; (iii) geochemical features such as high abundance and unique ratios of the platinum group (PGE) and other siderophile elements (Ni, Co); (iv) meteoritic isotopic ratios including ε_53Cr (⁵³Cr/⁵²Cr), ε_54Cr (⁵⁴Cr/⁵²Cr), ε_182W (¹⁸²W/¹⁸³W) or (¹⁸²W/¹⁸⁴W), ε_Os (¹⁸⁷Os/¹⁸⁸Os), ε_17O (¹⁷O/¹⁶O), ε_18O (¹⁸O/¹⁶O); and (v) cometary seeding of ³He/⁴He and racemic organic molecules (AIB) and possibly fullerenes (C₆₀). Relic nickel chromites and metasomatically derived sulfides may contain PGE nanonuggets. Alteration, burial metamorphism and open-system mobility of uranium in hydrous terrestrial environments renders preservation of meteoritic ε_207Pb (²⁰⁷Pb/²⁰⁴Pb) and ε_206Pb (²⁰⁶Pb/²⁰⁴Pb) values unlikely. Where least affected, PGE patterns of microkrystites and microtektite-bearing impact fallout units (impactites) are the reverse of terrestrial PGE patterns, including low Pd/Pt ratios, which provide some of the more readily identified and analytically practical criteria for identifying a meteoritic component. ε_Cr?–?ε_Cr relations in Barberton Greenstone Belt impact fallout units (3.26?–?3.24 Ga) identify a carbonaceous chondrite composition of the parental asteroids. PGE abundances (Ir, Pt) and ε_Cr isotope values allow mass-balance estimates of parental projectiles in the order of 20?–?30 km diameter. Ir and Pt mass-balance estimates correspond to projectiles ～20 km in diameter or larger in the Pilbara Craton for the JIL (>?2.63 Ga) and DGS4 (2.5?–?2.47 Ga) impact fallout units. The Ni, Co and Cr enriched composition of most Precambrian microkrystite spherules militates for mafic/ultramafic target crust which, coupled with the estimated diameter of the ensuing craters, implies the existence of maria-scale impact basins in oceanic-type crustal regions during the Archaean and Palaeoproterozoic.  相似文献