The role of the stress regime on microseismicity induced by overpressure and cooling in geologic carbon storage

Fluid injection in deep geological formations usually induces microseismicity. In particular, industrial‐scale injection of CO₂ may induce a large number of microseismic events. Since CO₂ is likely to reach the storage formation at a lower temperature than that corresponding to the geothermal gradient, both overpressure and cooling decrease the effective stresses and may induce microseismicity. Here, we investigate the effect of the stress regime on the effective stress evolution and fracture stability when injecting cold CO₂ through a horizontal well in a deep saline formation. Simulation results show that when only overpressure occurs, the vertical total stress remains practically constant, but the horizontal total stresses increase proportionally to overpressure. These hydro‐mechanical stress changes result in a slight improvement in fracture stability in normal faulting stress regimes because the decrease in deviatoric stress offsets the decrease in effective stresses produced by overpressure. However, fracture stability significantly decreases in reverse faulting stress regimes because the size of the Mohr circle increases in addition to being displaced towards failure conditions. Fracture stability also decreases in strike slip stress regimes because the Mohr circle maintains its size and is shifted towards the yield surface a magnitude equal to overpressure minus the increase in the horizontal total stresses. Additionally, cooling induces a thermal stress reduction in all directions, but larger in the out‐of‐plane direction. This stress anisotropy causes, apart from a displacement of the Mohr circle towards the yield surface, an increase in the size of the Mohr circle. These two effects decrease fracture stability, resulting in the strike slip being the least stable stress regime when cooling occurs, followed by the reverse faulting and the normal faulting stress regimes. Thus, characterizing the stress state is crucial to determine the maximum sustainable injection pressure and maximum temperature drop to safely inject CO₂.     

Still Bay and serrated points from Umhlatuzana Rock Shelter,Kwazulu-Natal,South Africa

Umhlatuzana Rock Shelter is a long-sequence Middle and Later Stone Age site in KwaZulu-Natal, South Africa. Jonathan Kaplan excavated the site and analysed the material in the 1980s as a rescue project. For many years thereafter the collection remained untouched, partly because of doubts raised about the stratigraphic integrity of the site. Using single-grain OSL dating we show that post-depositional mixing of sediment was restricted to time-specific, small-scale events. The OSL ages obtained for the Howiesons Poort and pre-Howiesons Poort are comparable to those of other southern African sites with unambiguous Howiesons Poort and Still Bay Industries. Based on morphological and other characteristics, we reason that the Still Bay is represented at Umhlatuzana, and announce the presence of a serrated point assemblage closely associated in time with the Still Bay points.     

基于胡塞尔现象学的旅游体验研究

国内学者在运用现象学方法研究旅游现象时,由于未能对旅游体验等概念进行现象学的澄清,导致旅游现象学研究始终在心理学意义上进行。本文运用现象学方法对旅游体验、旅游体验的整体性、旅游世界和生活世界以及旅游体验的自身构成等问题进行了现象学分析,并与目前代表性观点就上述问题的方法论进行商榷。本文认为,旅游世界从本源上讲是由形式上不在场、但本质上又时时牵扯在场的生活世界及其＂资粮＂构造并呈现着自身,旅游体验则是在异地场的非谋生实践体验与生活世界积淀的体验相互激荡构成的境域中构造自身。只有这样,才能够达到真正意义上用＂旅游学＂的视角构建旅游学科体系。     

唐代士大夫群体诚信之德的历史考察

具备文学素养,有知识,有能力,并具有强烈社会责任感的唐代士大夫群体,是唐代社会的精英阶层,他们很好地继承了中国传统的诚信观念。官僚士大夫秉承信为国本的政治理念,思想家们阐释食可去而信不可失的人生信条,史学家们将诚信化为善恶必书的治史原则,文人学士则将诚信融入激情飞扬的诗文之中。唐代士大夫的诚信思想,具有重要的研究价值。     

The left hand of the Enlightenment: truth,error, and integrity in Bayle and Kant*

Taking its cue from Hannah Arendt’s comment that ‘truth gets lost in the Enlightenment’ and Lessing’s parable of God’s ‘left hand’, this paper traces a historical shift in moral and religious thought: roughly from truth to sincerity. From traditional conceptions of conscience as conditional on the objective truth of its content, the paper moves on, via the Reformation and seventeenth-century Augustinian turn, to early modern debates on toleration and the ‘erring conscience’. It is argued that Pierre Bayle’s Commentaire Philosophique of 1686 can be read as a crucial catalogue for understanding the substitution of truth with sincerity (and error): so that not truth but truthfulness is considered to be essential for moral and religious justification. Moving from Bayle to Immanuel Kant, the paper then shows how many of the same questions rise in Kant’s late essay on theodicy, which is also an essay on sincerity or integrity, via the Book of Job. Through these two thinkers, various themes are connected: from conscience and sincerity to the problem of the conscientious persecutor. Finally, these themes of truth, error and integrity are linked to the modern debate on authenticity, and a framework is proposed for conceptualising these various shifts.     

对加强家庭廉政文化建设的思考

家庭廉政文化是党风廉政建设的重要内容。切实把握家庭廉政文化的内涵,针对存在的问题和原因,全面加强家庭廉政文化建设,是社会和谐发展的需要。     

中德经济发达地区城乡一体化模式比较——以长江三角洲与莱茵河下游地区为例

城乡一体化是伴随着工业社会、城市化时代的一种特有的社会经济现象,是人类社会生产力高度发达的一个重要标志,尤其在经济发达地区这种现象更加明显。中德两国有着不同的城市化发展过程和不同的时代背景,在工业化与经济发达区域内,城市化道路及其带来的城乡一体化类型、特征、模式与前景是有一定差异的。本文着重探索中国的长江三角洲与德国的莱茵-鲁尔地区的城乡一体化模式,从不同的视角、层面进行比较研究,试图从两国不同的地区比较得到有益的启示。     

建立融洽的师生关系 促进学生身心健康发展

师生关系直接影响教育效果;关爱学生是班主任搞好班级工作的前提;班主任要积极创造条件,主动亲近学生,细心体察、全面深入细致地了解学生的内心世界,为学生摆脱烦恼、化解困惑;对学生存在的问题多一点理解和宽容;用一颖平等的心与学生交往,尊重学生,促进学生身心的健康发展。