一种刀鲚生态养殖模式的构建

刀鲚(Coilianasus)是长江珍稀名贵的生殖洄游性、肉食性鱼类,自2020年1月1日0时起,长江10年内全面禁止刀鲚生产性捕捞。与此同时,衍生出刀鲚池塘养殖、工厂化养殖和网箱养殖模式,在这些养殖模式中,由于刀鲚长期处于肥水和高密度的养殖环境内,自身处于不安全的状态下,造成自身的免疫机能受到抑制和抗病力下降,导致养殖成活率低或大量死亡现象,造成刀鲚养殖规模一直没有大的进展。本研究通过对刀鲚各个生长发育过程的特征解析,将刀鲚生活史划分为水花开口、乌仔、稚鱼(夏花)、幼鱼和成鱼5个生长阶段,同时将刀鲚养殖所涉及的生态系统划分为浮游植物、原生动物、轮虫(卵)、枝角类、桡足类、底栖动物幼体、鱼(虾)苗、软靡、微囊配合饲料和有机碎屑、微生物8个层次,通过结合非生态系统构建了刀鲚生态养殖系统模式。通过构建该生态养殖模式对刀鲚养殖模式进行更加深入的研究和探讨,从而助力刀鲚产业的快速发展。     

Assessing the impacts of land cover and climate on runoff and sediment yield of a river basin

ABSTRACT

This study investigated the impacts of changes in land cover and climate on runoff and sediment yield in a river basin in India. Land Change Modeler was used to derive the future land cover and its changes using the Sankey diagram approach. The future climatic parameters were derived from five general circulation models for two emission scenarios with representative concentration pathways (RCPs) 4.5 and 8.5. The land cover and climate change impacts on runoff and sediment yield were estimated using SWAT model. The results show important changes in land cover and indicate that urban and agricultural areas strongly influence the runoff and sediment yield. Among the land cover and climate change impacts, climate has more predominant (70%–95%) impact. Runoff and sediment yield are likely to decrease in both RCP scenarios in the future period. The impacts of land cover changes are more prominent on sediment yield than runoff.     

Role of chemical processes on shear zone formation: an example from the Grimsel metagranodiorite (Aar massif,Central Alps)

Alpine deformation in the Grimsel granodiorite (Aar massif, Central Alps) at greenschist facies conditions (6.5 ± 1 kbar for 450°C ± 25°C) is characterized by the development of a network of centimetre to decametre localized shear zones that surround lenses of undeformed granodiorite. Localization of deformation is assumed to be the result of a first stage of extreme localization on brittle precursors (nucleation stage) followed by a transition to ductile deformation and lateral propagation into the weakly deformed granodiorite (widening stage). A paradox of this model is that the development of the ductile shear zone is accompanied by the crystallization of large amounts of phyllosilicates (white mica and chlorite) that maintains a weak rheology in the localized shear zone relative to the host rock so that deformation is localized and prevents shear zone widening. We suggest that chemical processes, and more particularly, the metamorphic reactions and metasomatism occurring during re‐equilibration of the metastable magmatic assemblage induced shear zone widening at these P–T–X conditions. These processes (reactions and mass transfer) were driven by the chemical potential gradients that developed between the thermodynamically metastable magmatic assemblage at the edge of the shear zone and the stable white mica and chlorite rich ultramylonite formed during the first stage of shear zone due to localized fluid infiltration metasomatism. P–T and chemical potential projections and sections show that the process of equilibration of the wall rocks (μ–μ path) occurs via the reactions: kf + cz + ab + bio + MgO + H₂O = mu + q + CaO + Na₂O and cz + ab + bio + MgO + H₂O = chl + mu + q + CaO + Na₂O. Computed phase diagram and mass balance calculations predict that these reactions induce relative losses of CaO and Na₂O of ～100% and ～40% respectively, coupled with hydration and a gain of ～140% for MgO. Intermediate rocks within the strain gradient (ultramylonite, mylonite and orthogneiss) reflect various degrees of re‐equilibration and metasomatism. The softening reaction involved may have reduced the strength at the edge of the shear zone and therefore promoted shear zone widening. Chemical potential phase diagram sections also indicate that the re‐equilibration process has a strong influence on equilibrium mineral compositions. For instance, the decrease in Si‐content of phengite from 3.29 to 3.14 p.f.u, when white mica is in equilibrium with the chlorite‐bearing assemblage, may be misinterpreted as the result of decompression during shear zone development while it is due only to syn‐deformation metasomatism at the peak metamorphic condition. The results of this study suggest that it is critical to consider chemical processes in the formation of shear zones particularly when deformation affects metastable assemblages and mass transfer are involved.     

Experimental study of the effect of roughness and Reynolds number on fluid flow in rough‐walled single fractures: a check of local cubic law

Local cubic law (LCL) is one of the most commonly applied physical laws for flow in single fractures (SF) and fractured media. The foundation of LCL is Darcian flow. This experimental study examines if LCL is valid for flow in a single rough fracture and how the fracture roughness and Reynolds number (Re) affect flow. Similar to the Moody diagram for flow in pipes, a diagram for flow in a single rough fracture has been generated to relate the friction coefficient with Re and the roughness. Under the experimental condition of this study, flow appears to be substantially different from Darcian flow. The flow law of q ∝ eⁿJ^m appears to be valid for describing the flow scheme where q, e, and J are the unit width flux, the average aperture, and the hydraulic gradient. The value of the power index m is found to be around 0·83 ～ 0·98, less than what has been used in Darcian flow (m = 1). The power index n is around 11·2 and 13·0, much greater than the n value used in the LCL (n = 3), and it increases with the average velocity. The Moody type of diagram shows that the friction factor for flow in SFs is influenced by Re and the roughness. It decreases with Re when Re is small, and becomes less sensitive to Re when Re is large enough. It also increases with the roughness. Copyright © 2010 John Wiley & Sons, Ltd.     

Pitfalls in predictions of rock properties using multivariate analysis and regression methods

Statistical methods are commonly used for prediction of geoscience and engineering properties. This commonly involves selection of a small number of variables among a large number of available geological, geophysical, petrophysical and engineering variables. The conventional view is to select the variables that have highest correlations with the variable of concern. In this article, we show that this may not always be a wise approach because it ignores a critical aspect of the variable interaction — suppression. We review the suppression phenomenon, and discuss three types of suppression in multiple linear regression of geoscience and reservoir properties. We present examples using wireline logs, seismic attributes, and other engineering parameters. We show that understanding the suppression phenomenon is important for selecting appropriate variables for optimal prediction of geoscience and reservoir properties.     

基于网络Voronoi图的大规模多仓库物流配送路径优化

由于存在多约束和多个优化目标,物流配送决策非常困难。针对城市多仓库物流配送问题,提出基于网络Voronoi图的空间启发式优化方法。从空间角度,将多仓库物流配送优化分解为区域分割和路径优化两个空间子问题。基于网络Voronoi覆盖进行服务区域初始划分,顾及仓库容量差异,进行区域边界修正,并创建初始解。路径优化将局部搜索范围限定在网络K近邻内,只搜索最有可能的空间邻域,迭代改进解的质量。该算法最小化路径数量和路径长度。利用深圳市的大规模多仓库物流配送问题测试算法性能。试验结果表明：本文方法能够在15min内求解6400个客户点的大规模物流配送问题,解的质量优于ArcGIS约10.8%,计算时间约为其21.2%。     

Wave climate scatter performance of a cycloidal wave energy converter

A lift based cycloidal wave energy converter (WEC) was investigated using potential flow numerical simulations in combination with viscous loss estimates based on published hydrofoil data. This type of wave energy converter consists of a shaft with one or more hydrofoils attached eccentrically at a radius. The main shaft is aligned parallel to the wave crests and submerged at a fixed depth. The operation of the WEC as a wave-to-shaft energy converter interacting with straight crested waves was estimated for an actual ocean wave climate. The climate chosen was the climate recorded by a buoy off the north-east shore of Oahu/Hawaii, which was a typical moderate wave climate featuring an average annual wave power P_W = 17 kWh/m of wave crest. The impact of the design variables radius, chord, span and maximum generator power on the average annual shaft energy yield, capacity factor and power production time fraction were explored. In the selected wave climate, a radius R = 5 m, chord C = 5 m and span of S = 60 m along with a maximum generator power of P_G = 1.25 MW were found to be optimal in terms of annual shaft energy yield. At the design point, the CycWEC achieved a wave-to-shaft power efficiency of 70%. In the annual average, 40% of the incoming wave energy was converted to shaft energy, and a capacity factor of 42% was achieved. These numbers exceeded the typical performance of competing renewables like wind power, and demonstrated that the WEC was able to convert wave energy to shaft energy efficiently for a range of wave periods and wave heights as encountered in a typical wave climate.     

基于Voronoi图与空间自相关的西北太平洋柔鱼资源空间聚集特征分析

以西北太平洋柔鱼Ommastrephes bartramii为例,基于2007—2010年中国鱿钓船的生产统计原始点位数据,利用Voronoi图和空间自相关方法,评估柔鱼资源的全局空间模式、局部空间聚集特征,并以空间可视化方式呈现。在渔业资源及空间分析中,高产值聚集的海域称为空间热点,而低产值聚集的海域称为空间冷点。研究表明,全局自相关统计量Morans I和General G均指示了西北太平洋柔鱼资源的聚集分布状态。局部空间自相关显示,2007和2009年均具有2个热点和1个冷点区域,2008年具有1个热点和1个冷点区域,2010年具有1个热点和2个冷点区域,这些热冷点呈南北向或东西向分布态势。热冷点格局的叠加图显示,研究区内存在1个强热点、1个弱热点和1个强冷点,其中弱热点覆盖的区域在4年间表现为热点和冷点的交互变动。对7—11月平均海表温度和叶绿素a浓度的分析显示,热点和冷点均为中心渔场,热冷点形成的温度条件无显著差异;热冷点形成的叶绿素a浓度范围为0.2~1.1mg/m3,其中冷点区域的浓度相对较高。     

徐州地区山西组砂岩岩石学特征及物源分析

徐州地区山西组砂岩中碎屑组分鉴定统计的结果显示,长石的含量为29%~52%,平均40%,明显高于周边地区。研究区岩石类型以长石砂岩为主,分选差-中等,磨圆次棱角状-次圆状,说明碎屑为短距离搬运;砂岩中斜长石的牌号显示源区主要为酸性岩;砂岩组分的Dickinson三角图解表明,物源总体来自大陆物源区的隆起基底,经分析确定物源区为丰-沛隆起。     

遥感中轴线法在江苏辐射沙洲潮沟演变监测中的应用

根据1988～2008 年的4 景TM 影像, 对江苏辐射沙洲地区5 条主要潮沟的动态演变研究方法进行了探讨。针对潮沟的特殊地形和复杂多变情况, 引入数学中的中轴线概念, 提出了遥感中轴线法, 通过中轴线位置的变化定量地表述潮沟演变。根据GIS 中Voronoi 图(V 图)的特性, 将中轴线的求取转换成V 图的生成过程, 用ArcGIS 软件实现, 将传统的目视解译方法改进为自动提取, 提取不同时相影像中轴主轴。研究结果表明: (1)用遥感中轴线法对不同时期的大型潮沟进行分析, 可较快、较准确地揭示潮沟的动态演变; (2)比较1988～2008 年的潮沟轴线, 西洋深槽变化最大, 西岸蚀退、东岸东移; 其他4 条潮沟均在南北方向上做往复摆动, 且逐渐趋于平缓。中轴线法可以实现对潮沟动态演变快速、准确地监测以及为整个辐射沙洲的开发建设提供理论基础。