Strain accumulation in sand due to cyclic loading: Drained cyclic tests with triaxial extension   总被引：1，自引：0，他引：1  

T. Wichtmann  A. Niemunis  Th. Triantafyllidis   《Soil Dynamics and Earthquake Engineering》2007,27(1):42-48

This paper presents results of numerous drained cyclic tests with triaxial extension. The influence of the strain amplitude, the average stress and the number of load cycles on the accumulation rate was studied. A simple cyclic flow rule was observed. Most findings confirm a previous study with cyclic triaxial compression tests. The test results serve as the basis of an explicit accumulation model.  相似文献   

海南地区溶藻弧菌遗传多样性的RAPD分析     

欧阳吉隆  周永灿  吴学贵  戴小连  王世锋  谢珍玉 《海洋科学》2011,35(7):30-36

以来源于泰国的菌株TG06003作对照,对采自海南地区的27株溶藻孤菌（Vibrio alginolyticus）环境菌株进行了随机扩增多态性DNA标记（RAPD）分析,其中6株为毒力菌株,另外22株为非毒力菌株。实验共得到70个多态性条带,多态性比率（PP13）为98．6％。基因多样度的算术平均数和加权平均数分别为0...  相似文献   

关于建立基础测绘公益性服务机制的探讨     

李春艳 《地理信息世界》2002,(3)

为更好地发挥基础测绘的公益性服务功能 ,特别是为领导决策机关和宏观管理、行政管理服务 ,需要建立基础测绘公益性服务机制 ,并完善基础地理信息数据的提供和使用政策  相似文献   

Numerical simulation of undrained insertion problems in geotechnical engineering with the Particle Finite Element Method (PFEM)     

《Computers and Geotechnics》2017

The paper presents total-stress numerical analyses of large-displacement soil-structure interaction problems in geomechanics using the Particle Finite Element Method (PFEM). This method is characterized by frequent remeshing and the use of low order finite elements to evaluate the solution. Several important features of the method are: (i) a mixed formulation (displacement-mean pressure) stabilized numerically to alleviate the volumetric locking effects that are characteristic of low order elements when the medium is incompressible, (ii) a penalty method to prescribe the contact constraints between a rigid body and a deformable media combined with an implicit scheme to solve the tangential contact constraint, (iii) an explicit algorithm with adaptive substepping and correction of the yield surface drift to integrate the finite-strain multiplicative elasto-plastic constitutive relationship, and (iv) the mapping schemes to transfer information between successive discretizations. The performance of the method is demonstrated by several numerical examples, of increasing complexity, ranging from the insertion of a rigid strip footing to a rough cone penetration test. It is shown that the proposed method requires fewer computational resources than other numerical approaches addressing the same type of problems.  相似文献   

空气潜孔锤钻进是提高钻进效率的有效途径     

刘景辉  谭效林  路庆海  赵联忠 《中国煤炭地质》2009,(3):63-65

空气潜孔锤冲击钻进与常规回转钻进技术相比,是以动载钻头冲击破碎岩石方式取代静载切削岩石的方式;岩石的体积破碎代替了研磨剪切破碎;是目前提高钻进效率的最佳钻进技术之一。在同井同钻机钻进时,其钻效可较常规钻进提高11-18倍;在邻井相同地层、相同技术要求时,其钻效可提高13倍左右;在同一勘探区、相同技术要求时,其钻效可提高9倍左右。通过反复对比论证,认为空气潜孔锤钻进能有效提高钻进效率,较好的体现出其潜在的经济与环保价值。  相似文献   

坛紫菜耐高温品系选育及经济性状的初步研究   总被引：10，自引：1，他引：9  

陈昌生  纪德华  谢潮添  徐燕  梁艳  郑永健  史修周  王凤霞  赵玲敏 《海洋学报》2008,30(5):100-106

将人工杂交选育的坛紫菜新品系Z-26,Z-61,Z-81,Z-17的子3代(F₃)与野生型对照组进行遗传性状的比较,旨在筛选耐高温品系。实验结果表明:(1)在高温29℃下培养40 d,人工选育的4个新品系丝状体均能正常生长发育,其中Z-26丝状体生长较快,Z-61在29℃下较易成熟,95%的营养藻丝发育成孢子囊枝,Z-17只有30%形成孢子囊枝;(2)Z-26和Z-61品系的叶状体在30℃下培养10 d,虽然藻体变白,但没有死亡,此时将其移至21℃下恢复培养3~4 d,藻体逐渐恢复为原有的色泽;(3)Z-81和Z-17的叶状体在29℃下培养7~10 d,虽然藻体发白但尚未死亡,移至21℃下培养基本可恢复正常,但在30℃下培养10 d,藻体腐烂不可恢复;(4)野生型对照组不耐高温,藻体在27℃下培养5 d就腐烂死亡,人工选育的4个品系耐受高温的幅度比野生型对照组高1~3℃;(5)4个品系叶状体在26~28℃温度下培养10 d后,其主要的藻胆蛋白和叶绿素a的含量与21℃培养下的含量差异不显著,说明短时间的高温培养并不影响其品质。  相似文献   

生物采油解堵剂中产蛋白酶菌株的筛选及培养条件优化     

左佳敏  何连芳  张玉苍  刘飞 《东北石油大学学报》2012,(2):96-102,129,130

为研究生物酶采油解堵剂中产蛋白酶菌株的初、复筛选及培养条件优化,从大庆原油样品中筛选菌种,通过水解酪素的透明圈实验及福林酚测蛋白酶酶活的方法进行菌株的初、复筛选;以蛋白酶酶活为优化指标,采用单因素实验对筛选的产蛋白酶菌株的培养基及培养条件进行优化,优化最适培养基:可溶性淀粉为15g/L,蛋白胨为20g/L,酵母膏为20g/L,NaCl为1.0g/L,CaCl2为0.02g/L,Na2HPO4为0.2g/L,NaH2PO4为0.1g/L;在初始pH为6.0、接种量为5%(体积分数)、温度为31℃、摇床转速为160r/min的条件下,培养72h后,菌株的蛋白酶酶活为551.0U/mL,为复筛选菌株的蛋白酶酶活的22.92倍,即为菌株生长繁殖及代谢的最佳条件,能够获得更高的蛋白酶酶活,有利于后续实验的进行.结果表明:菌株产蛋白酶对原油作用效果为发酵液表面张力从作用前的56.2mN/m降低到作用后的30.5mN/m,表面张力显著降低,还有降解降黏原油等效果,具有一定的研究价值.  相似文献   

Black-legged kittiwakes as indicators of environmental change in the North Sea: Evidence from long-term studies     

S. Wanless  M. Frederiksen  B.E. Scott 《Progress in Oceanography》2007,72(1):30-38

Top predators, particularly seabirds, have repeatedly been suggested as indicators of marine ecosystem status. One region currently under pressure from human fisheries and climate change is the North Sea. Standardized seabird monitoring data have been collected on the Isle of May, an important seabird colony in the northwestern North Sea, over the last 10-20 years. Over this period oceanographic conditions have varied markedly, and between 1990 and 1999 a major industrial fishery for sandlance (Ammodytes marinus), the main prey of most seabird species, was prosecuted nearby. Sandlance fishing grounds close to seabird colonies down the east coast of the UK were closed in 2000 in an attempt to improve foraging opportunities for breeding seabirds, particularly black-legged kittiwakes (Rissa tridactyla). Initially this closure seemed to be beneficial for kittiwakes with breeding success recovering to pre-fishery levels. However, despite the ban continuing, kittiwakes and many other seabird species in the North Sea suffered severe breeding failures in 2004. In this paper, we test the predictive power of four previously established correlations between kittiwake breeding success and climatic/trophic variables to explain the observed breeding success at the Isle of May in 2004. During the breeding season, kittiwakes at this colony switch from feeding on 1+ group to 0 group sandlance, and results up until 2003 indicated that availability of both age classes had a positive effect on kittiwake breeding success. The low breeding success of kittiwakes in 2004 was consistent with the late appearance and small body size of 0 group sandlance, but at odds with the two variables likely to operate via 1 group availability (lagged winter sea surface temperature and larval sandlance cohort strength in 2003). The reason for the discrepancy is currently unknown, but analysis of 1 group sandlance body composition indicated that lipid content in 2004 was extremely low, and thus fish eaten by kittiwakes during pre-breeding and early incubation were likely to be of poor quality. Monitoring of reproductive success of kittiwakes, although useful, was clearly not sufficient to tease apart the complex causation underlying the 2004 event. Monitoring programs such as this, therefore, need to be complemented by detailed research to identify the mechanisms involved, and to attribute and predict the effects of natural and human-induced environmental change.  相似文献   

各种类型河蟹育苗用水的水质分析     

石俊艳  刘中  王晓光  丁茂昌  韩守谨 《海洋科学》2001,25(8):49-51

近几年,河蟹人工育苗已成为我省沿海种苗培育单位的重要产业 ,随着育苗规模的不断扩大及所带来的可观经济效益,各地又因地制宜发展起地下海水、浓缩海水的育苗生产,为搞清这几种育苗水体的水质特点 ,作者对这几种水体进行了分析检测,以服务于生产 ,为河蟹育苗的健康发展提供科学依据。１工作内容和方法１．１采样点自然海水采于营口市老边区三道沟和盘锦市二界沟;浓缩海水采于营口市青石岭育苗室及营口盐 　种型苗水ｐ ＣＤ营盐含量Ｔａｂ .1　ｐＨ ,ＣＯＤａｎｄｎｕｔｒｉｔｉｏｎｓａｌｔｏｆｅｖｅｒｙｋｉｎｄｏｆｂｒｅｅｄｉｎｇｗａ…  相似文献   

草鱼出血病病毒株的筛选   总被引：1，自引：0，他引：1       下载免费PDF全文

罗毅志  杨广智  叶雪平 《海洋与湖沼》1993,24(5):503-506

为筛选适用草鱼出血病细胞疫苗工厂化生产的病毒株，于１９８７－１９８９年，在浙江湖州地区采集了１２个具典型草鱼出血病症状的病鱼材料，通过比较它们的毒力，对细胞的适应性，免疫原性，研究病毒在细胞内的增殖动态，细胞病变特征，毒株保存。结果表明，筛选出的ＺＶ－８８０２和ＺＶ－８９０９两毒株，其毒力高，免疫原性强，并能在细胞中大量增殖。应用这两株毒株制备的细胞疫苗，其免疫保护率在８５％以上。  相似文献