Setting quotas using provisional data: a case study from the South Australian abalone fisheries     

J Dent  S Mayfield  B Stobart  J Carroll 《新西兰海洋与淡水研究杂志》2016,50(3):371-388

Stock assessments of quota or effort managed fisheries in which the duration of the fishing season is 12 months are invariably delivered well into the subsequent fishing season. As a result, quotas are frequently based on year-old data. This delay is often unavoidable because it may take months to collect, collate and analyse data necessary to assess fishery performance. The South Australian fisheries for blacklip (Haliotis rubra Leach, 1814) and greenlip abalone (H. laevigata Donovan, 1808) have addressed this issue by using provisional data on current stock status to inform application of the harvest strategy decision rules that set the quota for the next year. The primary index of relative abundance for these fisheries is catch per unit effort (CPUE). Our study uses 25 years (1988–2012) of CPUE data to quantify the differences between the provisional and complete-season CPUE estimates at the spatial scales used to assess the fisheries. We demonstrate that, in most cases, there was a strong relationship between the provisional and complete-season CPUE estimates for both species, with little evidence of bias. As the provisional CPUE estimates were a reliable and accurate predictor of the complete-season CPUE estimates, this provides a high degree of confidence in using provisional CPUE estimates to set quotas, thereby overcoming the difficulty of basing decisions on aged data. These findings are likely to be applicable to other fisheries, particularly those where much of the annual catch is obtained (or effort expended) in a short time period at the commencement of the fishing season.  相似文献   

贵州铜仁坝黄磷矿中铀赋存状态的逐级化学提取研究   总被引：1，自引：1，他引：0  

王志罡  谢宏  杨旭  周忠容 《岩矿测试》2018,37(3):256-265

贵州铜仁坝黄磷块岩矿床富集放射性元素铀,利用逐级化学提取分析方法对该地区黄磷矿中铀的赋存状态进行探究,有助于进一步探讨磷块岩型铀矿的分布规律、成矿机理及铀资源的综合开发。本文采用经修改的Tessier法流程,提取了水溶态、可交换离子态、碳酸盐结合态、铁锰氧化物结合态、有机质黄铁矿态、强酸提取态和残渣态等七种不同形态的铀。研究发现:黄磷矿中的铀主要以独立铀矿物和类质同象置换的形式存在,分别占37.83%、37.21%,少量铀(占24.96%)以分散吸附形式存在。分析表明:独立铀矿物在富磷、黄铁矿脉和镜面擦痕发育的岩层中含量较高,说明热液活动有利于独立矿物形式铀的富集;类质同象铀与黄磷矿中的磷含量呈正相关关系,铀元素可能是以离子置换的方式赋存于胶磷矿的晶格缺陷中;吸附形态铀的含量受到岩石中黏土矿物含量和黄铁矿脉的影响,有机质黄铁矿态是吸附形态铀存在的主要方式,少量铀通过扩散作用吸附于黏土矿物表面。除类质同象铀因其存在形式不易被提取利用外,独立铀矿物及吸附形态铀对于未来优化资源配置具有现实意义。  相似文献   

Littoral and offshore communities of diatoms,cladocerans and dipterous larvae,and their interpretation in paleolimnology   总被引：6，自引：0，他引：6  

David G. Frey 《Journal of Paleolimnology》1988,1(3):179-191

The remains of diatoms, cladocerans, and midges are usually the most abundant of freshwater organisms and to now have been most useful in interpreting past conditions in a lake. Each taxocene consists of two separate communities, one in the warm littoral zone and the other offshore. Remains of inshore organisms are moved offshore by wind-generated currents, the amount of transport varying with individual characteristics of the lakes. Nowhere do remains of the two communities become completely integrated numerically, although the remains of the littoral chydorid Cladocera become integrated by species before they are incorporated into the sediments. The taxa of the planktonic Eubosmina and of the offshore midges correspond to levels of productivity in present-day lakes, and hence changes in the fossil record are commonly regarded as indicating eutrophication over time. The deepwater midges respond to the concentration of dissolved oxygen in deep water, which may be controlled more by a decrease in volume of deep water through accumulation of sediments than by any real increase in edaphic productivity. While such changes are going on offshore during the Holocene, the littoral communities of cladocerans and midges are scarcely changing at all, suggesting a different response of the inshore from the offshore communities to longterm changes resulting from increasing productively or from other functions. Thus, considering these different responses of the two communities of organisms and their incomplete mixing, the remains of littoral and offshore taxa recovered from an offshore core of sediments must be tabulated separately and interpreted separately. For any studies involving accumulation rates, there must be an understanding of the integration of inshore and offshore remains, its variation over the lake bottom, and how it may have varied with marked fluctuations in water level.This is the third of a series of papers to be published by this journal that was presented in the paleolimnology sessions organized by R. B. Davis and H. Löffler for the XIIth Congress of the International Union for Quaternary Research (INQUA), which took place in Ottawa, Canada in August 1987. Drs. Davis and Löffler are serving as guest editors of this series.  相似文献   

三维工业物体的一种关系数据结构及协调标号算法     

王新华  李德仁 《武汉大学学报(信息科学版)》1996,(3)

提出一种用于描述三维工业物体的关系数据结构，将关系匹配归结为一个关系同构或协调标号问题。提出了３种修剪算子，它充分利用关系数据结构的多重约束、一对一映射约束、关系符号表与基元符号表的映射作为知识启发来修剪搜索树，从而大大简化了物体匹配中的协调标号或关系同构问题  相似文献   

福建南平伟晶岩中的柱磷锶锂矿—磷铝钙锂石     

倪云祥  杨岳清 《矿物学报》1993,13(4):346-353

柱磷锶锂矿与磷铝钙锂石是一完全类质同象系列（Ｓｒ，Ｃａ）的两个端元矿物，二者在自然界都十分罕见，仅少量产于花岗伟晶岩中，所报道的产地也廖廖无几。笔者于１９８５年在福建南平花岗伟晶岩田的白云母－钠长石－锂辉石型伟晶岩中发现了这两种矿物、二者在国内均属首次发现，本文详细地报道了南平柱磷锶锂矿－磷铝钙锂石的产状、物理性质、化学成分、Ｘ射线衍射特征及矿物晶胞参数等。研究指出：南平柱磷锶锂矿是伟晶岩中原生大  相似文献   

试论复杂链状氧化物—黑钨矿的晶体化学特征     

陈图华 《矿物学报》1988,(1)

对不同世代的10个天然黑钨矿和1个人工合成的黑钨矿进行了物理性质、化学成分、粉晶X射线衍射、穆斯堡尔谱和溶矿物相试验及电子扫描分析等测试工作。结果表明;黑钨矿中含有较多的Nb、Ta、Sc、Y、Yb和Fe~(3+)等微量元素,它们以类质同象的形式呈三种方式替代Mn、Fe~(2+)和W_(6+)离子,并分别占据在Fe(Mn)O_6八面体和歪曲度大的WO_6畸变八面体中;因此,黑钨矿结构中的W不是以WO_4四面体状态存在,而是形成Fe(Mn)O_6与WO_6以角顶相连的复杂链状氧化物结构体。  相似文献   

复杂钴矿石中钴镍赋存状态研究   总被引：3，自引：0，他引：3  

甘树才  周少红 《岩矿测试》2000,19(1):42-44

利用相态分析方法,配合扫描电镜、Ｘ光衍射分析及红外光谱分析等测试手段,对某铜钴矿化区钴矿石中钴镍的赋存状态进行了研究。综合分析查定了钴镍在该铜钴矿化区的赋存状态主要有：①钴镍以含钴的镍黄铁矿产出;②钴镍与铁呈类质同象状态存在于黄铁矿、黄铜矿和菱铁矿中;③钴镍以吸附态存在于伊利粘土矿物中。  相似文献   

江西相山铀矿田居隆庵矿床钍元素地球化学特征研究     

孟艳宁  范洪海 《高校地质学报》2013,19(1):148-158

居隆庵矿床是江西相山铀矿田西部的一个大型铀- 钍混合矿床,通过对一系列蚀变（围岩）及矿化样品的元素地球 化学分析,详细讨论了与钍矿化有关的主量及微量元素的特征。钍元素富集的样品中,主量元素的总体特点是富钙、富磷, 且Na2O>K2O。在早期碱交代阶段,往往只形成单铀型矿化,而钍矿化主要形成于铀- 萤石、水云母化阶段。蚀变和矿化样 品的稀土元素分配形式不同,钍矿化与稀土元素特别是重稀土元素高度相关,微量元素Re,Y,Se,Pb 与钍矿化高度相关, 揭示钍矿化形成与金属硫化物及磷钇矿等磷酸盐密切相关。  相似文献   

Multiple hazard incidents lifecycle cost assessment of structural systems considering state‐dependent repair times and fragility curves          下载免费PDF全文

Ehsan Fereshtehnejad  Abdollah Shafieezadeh 《地震工程与结构动力学》2016,45(14):2327-2347

The performance and serviceability of structural systems during their lifetime can be significantly affected by the occurrence of extreme events. Despite their low probability, there is a potential for multiple occurrences of such hazards during the relatively long service life of systems. This paper introduces a comprehensive framework for the assessment of lifecycle cost of infrastructures subject to multiple hazard events throughout their decision‐making time horizon. The framework entails the lifecycle costs of maintenance and repair, as well as the salvage value of the structure at the end of the decision‐making time horizon. The primary features of the proposed framework include accounting for the possibility of multiple hazard occurrences, incorporating effects of incomplete repair actions on the accumulated damage through damage state‐dependent repair times, and requiring limited resources in terms of input data and computational costs. A dynamic programming procedure is proposed to calculate the expected damage condition of the structure for each possibility of the number of hazard incidents based on state‐dependent fragility curves. The proposed framework is applied to a moment‐frame building located in a region with high seismicity, and lifecycle costs are evaluated for six retrofit plans. The results displayed variation in the ranking of the retrofit actions with respect to decision‐making time horizon. Furthermore, the sensitivity analyses demonstrated that disregarding repair time in the lifecycle cost analysis can result in false identification of unsafe retrofit actions as optimal and reliable strategies. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

On comparative probabilities for normal confidence intervals by pearson's Types III and VII, and the Edgeworth series models for biotite data     

S. K. Banerjee  E. L. Zodrow 《Mathematical Geology》1982,14(6):565-575

Biotite crystals were counted in standard thin sections which originated from the diamond drill core of the mafic norite formation at Strathcona mine, Sudbury Nickel Irruptive. Pearson's method of moments is suitable to fit Types III and VII to the biotite data and its log ₁₀ transformation values, as the number of samples (thin sections)is large (351).Based on the two models and the Edgeworth series (utilizing the log ₁₀ data)probability values p,that biotite occurrences lie in the interval mean ± Z standard deviations is derived. Results are compared with the usual normal probability values p_Z corresponding to Zand it is shown that the Edgeworth series generated the largest pvalues for intervals when p_Z values are large; for intermediate or lower p_Z s. Types VII and III models produced larger ps, relative to the Normal and the Edgeworth series.  相似文献