岩石裂隙可视化渗流装置可行性及试验研究     

刘杰  黎照  杨渝南  张子睿  唐洪宇  高进  申剑 《岩土力学》2020,41(12):4127-4136

自主研发一套能从可视化角度反映岩石单裂隙渗流特征的装置，并以模拟岩石的变形模量为主要技术指标，获得了K39透明类岩石材料的添加剂含量为：促进剂0.8%、硬化剂0.6%、消泡剂0.6%；通过二次翻模精确复刻技术得到原岩裂隙面粗糙度，为研究细微观裂隙渗流提供技术支撑。通过可视化装置与原岩装置模拟试验，得到两者之间的差异性系数，进而推出原岩渗流流量的修正公式，获得了渗流量、渗流面积等能反映原岩性能的相关参数。阐明了K39透明类岩石材料对渗流量的影响效应?总及其影响的内在机制；与以ELE仪器为研究平台的渗流试验进行异同性分析，得到两者渗流量之间存在差异的相对变化系数，证明可视化渗流装置研究岩石裂隙渗流是合理可行的。利用该装置开展空间多角度试验，在耦合粗糙度、渗透压、围压、空间多角度、水自重效应等多因素下，通过渗流面积数字化自识别技术为精确获取岩石渗流特征的相关参数提供基础。  相似文献   

Environmental responses of jellyfish polyps as drivers of medusa populations off the coast of Namibia     

L Ziegler  MJ Gibbons 《African Journal of Marine Science》2018,40(3):323-329

Jellyfish populations in the southeastern Atlantic off the coast of Namibia have increased subsequent to the decline of small pelagic fisheries at the end of the 1960s, although the environment there has also become warmer and the waters off Walvis Bay have become richer in zooplankton in recent years. Laboratory experiments were conducted with the scyphozoan jellyfish Chrysaora fulgida to investigate the effects of food density (0, 30, 70, 100 or 150 Artemia nauplii 200 ml^?1), feeding frequency (once daily or once every third day) and water temperature (12, 16 or 20 °C) on the asexual reproduction, growth and development of polyps. The results of a generalised linear mixed-effects model reveal that all variables impacted asexual reproduction, with greater polyp production attained at higher food concentrations, increased feeding frequencies and increased temperatures. The most common mode of asexual reproduction was by lateral budding. These laboratory results suggest that polyps of C. fulgida may have proliferated off Namibia in recent times, which would contribute to increased numbers of jellyfish there.  相似文献   

Chrysophyte reproduction and resting cysts: A paleolimnologist's primer     

Craig D. Sandgren 《Journal of Paleolimnology》1991,5(1):1-9

Chrysophyte algae produce siliceous resting cysts (stomatocysts) that are becoming an increasingly useful class of paleoecological indicator microfossils. This paper provides a review of the role that stomatocysts play in the life cycle and reproductive ecology of freshwater planktonic chrysophytes. Such information provides paleolimnologists with greater insight into the ecology of the vegetative, planktonic growth phase of species contributing stomatocysts to lacustrine microfossil assemblages. Specific chrysophyte reproductive characteristics discussed include: temporal dynamics of vegetative growth and encystment, cyst induction, cyst survivorship, germination requirements and recruitment strategies. This information serves as an introduction to a special issue of the Journal of Paleolimnology which is dedicated to the Application of Chrysophyte Stomatocysts in Paleolimnology.This is the first in a series of four papers published in this dedicated issue entitled Application of Chrysophyte Stomatocysts in Paleolimnology. Dr. C. D. Sandgren served as guest editor for these papers.  相似文献   

彩色图像复制的加网技术及其应用     

翟琴 《测绘学院学报》1999,(2)

加网技术的变化直接影响彩色图像复制的质量, 作者主要从彩色图像复制的基本原理出发, 论述了调幅加网技术和调频加网技术, 并对两种加网技术作一比较, 分析了调频加网技术在当今时代具有广阔的应用前景。  相似文献   

暗纹东方鲀的人工繁殖   总被引：5，自引：0，他引：5       下载免费PDF全文

陈亚芬  陈源高  刘正文 《湖泊科学》1999,(2)

１９９５－１９９７年,以暗纹东方鲀进行人工繁殖,经ＬＨＲＨ－Ａ_２催熟处理,雌鱼的性腺可以发育到Ⅳ期末,性腺发育达到Ⅳ期中以后的雌鱼注射激素能引起正常的排卵反应．试验用的催产药物为 ＬＨＲＨ－Ａ_２、ＨＣＧ和ＰＧ．在水温 １６－２１℃的条件下,效应时间为６－８６ ｈ,平均催产率为８７．５％,平均受精率为 ６１．８％,平均孵化率为 ５１．７％．在水温２０℃时,胚胎发育历时１５４ ｈ孵出  相似文献   

体制与认同：高校地理院系调整的启示     

孙俊  潘玉君  李琳  郭玉珊  和晓江  宋慧仙  段生鑫 《地理研究》2022,41(4):960-979

地理院系调整研究旨在通过对地理学认同产生不利影响的高校地理院系调整的解析,揭示地理学发展存在的学科与体制认同问题。基于对高校地理院系调整的回顾,分析地理院系调整的原因及影响,并结合当前地理院系发展态势阐明其启示。结果显示：学科认同与院系调整互为关联,尽管地理院系调整导致的解体并不表明地理学的终结,一般意义的调整也存在积极影响,但不同类型地理院系调整对地理学（特别是人文地理学）学科认同的不利影响仍然明显,并影响着体制层面的学科再生产。地理院系调整的发生是多因素共同影响的结果,复杂多样的因素及其影响表明地理院系面临竞争,需要地理学者既“正名”（塑造科学性、统一性的学科形象）又“指实”（完整的院系体制建设）;既“向内”（地理院系及地理学家的努力）又“向外”（维护地理学及地理院系的完整性认同）的集体努力,在强化地理学综合性基础上形成“多轨发展”机制,强化地理学学科与体制认同。“跨学科典范”的塑造或许是当前地理院系应努力的现实目标。  相似文献   

凡纳对虾人工繁殖的初步研究     

刘永 《广东海洋大学学报》2002,22(4):19-23

研究了海水比重的变化对凡纳对虾亲虾人工繁殖活动的影响及换水对亲虾交配率的影响。试验采用剪眼柄、强化培育、控光、换水等技术措施 ,将凡纳对虾培育成熟并使之自然交配产卵 ,孵化出无节幼体 ;亲虾的平均产卵量可达 1 6万粒左右 ,卵的受精孵化率可达 80 %以上。结果表明 :适时换水可将亲虾的交配率从 4 6 %提高到 79% ;凡纳对虾人工繁殖的适宜海水相对密度为 1 0 1 6以上。  相似文献   

夜光藻配子细胞实时荧光定量PCR检测方法的建立与应用     

张樱馨  宋书群  李才文 《海洋与湖沼》2022,53(6):1385-1395

夜光藻是我国广泛分布的赤潮原因种之一,其有性繁殖在种群增长中的作用尚不明确,定量分析配子细胞是研究夜光藻有性繁殖过程的重要手段。利用实时荧光定量PCR技术,以夜光藻rRNA基因的18S-ITS1为靶区域,建立了定量检测夜光藻配子细胞的方法。以配子细胞基因组DNA和含目的片段的重组质粒分别建立标准工作曲线,二者均呈现良好的线性响应,检出限分别为每反应0.17个细胞和10²个拷贝,满足定量检测应用需求。应用该方法对2015年逐月采集的胶州湾环境样品进行检测,并首次对夜光藻配子细胞的季节变化、水平分布与垂直分布进行了研究。结果表明,调查海域夜光藻配子丰度呈冬末春初、夏季双峰分布,范围为18.12~9.70×10⁵ cells/L;在水深小于10m的湾内近岸站位,配子丰度较低,垂直分布均匀;在湾中心、湾口和湾外的深水站位,配子丰度较高,仅在2~3月、7月和11月出现垂向差异。夜光藻配子细胞对种群增长和存续有潜在的积极意义,其丰度在营养细胞丰度高值期相对较高,在营养细胞丰度极低时仍可普遍检出。丰富了对近岸海域夜光藻配子细胞时空分布的认识,为深入研究夜光藻的种群增长模式、进一步探究其赤潮暴发的内在机理奠定了基础。  相似文献   

Does the zooplankton prey availability limit the larval habitats of pike in the Baltic Sea?     

Meri Kallasvuo  Maiju Salonen  Antti Lappalainen 《Estuarine, Coastal and Shelf Science》2010

The objectives of this study were to (1) investigate whether the availability of suitable zooplankton prey limits the distribution of the coastal larval areas of pike (Esox lucius) in two archipelago areas of the northern Baltic Sea and (2) compare the availability of zooplankton prey in spring between different types of coastal littoral habitat. According to the results, reed belt habitats formed by Phragmites australis constitute hot spots for zooplankton prey in the coastal ecosystem. During the spring, reed-covered shores of the inner archipelago maintained more than 10 times higher densities of copepods and cladocerans, the preferred prey for larval pike, compared to the other studied shores. Temperature conditions were also most favourable in the reed belt habitat. Thus, the reed belts of the inner and middle archipelago were shown to form the best habitat for larval pike in the coastal area of the northern Baltic Sea, and this was also the only habitat where pike larvae were found. Our results suggest that the poor survival and recruitment of pike in the outer archipelago, however, cannot exclusively be explained by sub-optimal feeding conditions of the larvae. There are also other important factors, presumably connected to the exposure to the open sea, that affect the distribution of the pike larvae. Our results, however, highlight the importance of sheltered coastal reed belt shores as reproduction habitat for spring-spawning fish in the northern Baltic Sea. Further, this study disproves the assumption that the seaweed bladder wrack (Fucus vesiculosus) forms a reproduction habitat for pike in the coastal area.  相似文献   

Map Libraries     

Mingguang Wu  A-Xing Zhu  Li He 《The Cartographic journal》2013,50(3):273-278

Colour distortion, which is caused by the unavoidable mismatch between a map’s gamut and a device’s gamut, negatively affects the semiotic quality of maps. Cartographic communication often suffers from undesirable colour inconsistency. This method models cartographic colour reproduction as a constrained transform problem, namely, adapting a map’s gamut to fit a device’s gamut while preserving the semiotic quality. First, the characteristics of the map’s gamut are investigated by considering cartographic principles, and the fundamental concerns of preserving semiotic quality are proposed. Then, the self-organizing map method is introduced to iteratively optimize the cartographic colour reproduction. We implement this method and evaluate it based on a series of thematic maps. The results indicate that the proposed algorithm offers better results than two alternatives in terms of facilitating cartographic colour reproduction.  相似文献