污染大气中浑仪,简仪的带锈防护

浑仪、简仪（以下简称两仪）在高PH、大气污染和日晒雨淋环境中的腐蚀是一种动态加速腐蚀过程。采用合成的双唑胺铜缓蚀剂和有机硅改性的甲基丙烯酸树脂,并分别复配成协同缓蚀剂群和含有增效稳定剂的封护剂。采用这两种材料和脱水后再防护的工艺,使带锈防护后的浑仪、简仪的腐蚀低于无污染大气中的速率。用电化学方法评价了防护技术的可行性,根据腐蚀与人工老化试验结果讨论了防护材料性能与腐蚀环境和带锈防护的关系,采用XPS分析方法探索了双唑胺比BTA更适用于两仪防护的原因。     

Multiphase flow simulation through porous media with explicitly resolved fractures

Accurate simulation of multiphase flow in fractured porous media remains a challenge. An important problem is the representation of the discontinuous or near discontinuous behaviour of saturation in real geological formations. In the classical continuum approach, a refined mesh is required at the interface between fracture and porous media to capture the steep gradients in saturation and saturation‐dependent transport properties. This dramatically increases the computational load when large numbers of fractures are present in the numerical model. A discontinuous finite element method is reported here to model flow in fractured porous media. The governing multiphase porous media flow equations are solved in the adaptive mesh computational fluid dynamics code IC‐FERST on unstructured meshes. The method is based on a mixed control volume – discontinuous finite element formulation. This is combined with the P_N+1DG‐P_NDG element pair, which has discontinuous (order N+1) representation for velocity and discontinuous (order N) representation for pressure. A number of test cases are used to evaluate the method's ability to model fracture flow. The first is used to verify the performance of the element pair on structured and unstructured meshes of different resolution. Multiphase flow is then modelled in a range of idealised and simple fracture patterns. Solutions with sharp saturation fronts and computational economy in terms of mesh size are illustrated.     

卢梭回归自然的美学之境

卢梭的“自然美”思想丰赡深邃,精远宏阔.从美育目标、理念、重点三个层面梳理了卢梭自然主义美育思想的核心内容,将其教育特点归纳为整体性、平民性、情感性和自然性,并着重阐述了这一思想对新时期我国美育工作的四个重要启示:即注重美育工作的辩证性;尊重美育实践的主体性;激励美育过程的情感性;倡导美育内容的生态性.     

Gardens and gardening in early medieval Spain and Portugal

This is an overview of the range of gardens, garden plants and garden work in early medieval Spain and Portugal, and of the kinds of relevant source material available. There were different kinds of garden, from the architectural gardens of Andalusī rulers and officials to peasant plots in the countryside. Fine gardens were closely associated with an elite and were southern rather than northern. Productive gardens could be found all over the peninsula; vegetables were clearly grown in them, with the emphasis on pulses, but they constituted a small proportion of produce. Fruits were exceptionally important as a source of vitamins, sugar and mineral salts.     

新中国土地改革后新富农产生的规模与分布研究

从土地改革结束到农业集体化高潮前夕,新富农的出现从全国范围来看是稀少而缓慢的。在各省之间,农民的富裕程度与新富农比重大小关系不明显,但在同一地区内来看,两者呈现正相关关系。同时,在农业合作化程度较高亦即是较早对新富农采取限制政策的地区,新富农的比重并不一定低于甚至高于其他地区。这说明多种因素对新富农的产生、发展发生作用,单因素的分析不能解释清楚新富农这个复杂的社会经济问题。     

国民经济恢复时期北京的失业知识分子救济政策及其成效

国民经济恢复时期,面对失业和人才需求关系的矛盾,城市失业知识分子受到党和政府的高度关注。北京市的失业知识分子虽人数不多,但呈现出一定程度的复杂性。为此,北京市根据党和国家的政策,从首都社会秩序的稳定和首都建设的人才需求出发,在较短的时间内,有计划有步骤地对失业知识分子进行了必要的社会救济,达到了预期的目标。同时,实际操作中也遇到了一些不容回避的问题。     

Chemical and mineralogical characterization of Aguada Portezuelo pottery from Catamarca,north-western Argentina: PIXE,XRD and SEM-EDS studies applied to surface pre- and post-firing paints,slips and pastes

Particle-induced X-ray emission (PIXE), X-ray diffraction (XRD), electron microprobe analysis (EDS) and scanning electron microscopy (SEM) analytical techniques were used to characterize surface paints in pre- and post-fired Aguada Portezuelo decorated pottery. Surface paintings in black, white, red, brown, burgundy and ochre were analysed. Major, minor and trace elements were detected by PIXE, whereas XRD and SEM-EDS gave information on the main mineral phases and the characteristic morphology for each analysed pigment. The results obtained indicate that the main colour groups can be easily discriminated by PIXE, and they are characterized by only one pigment for each colour: hematite (red) and manganese mineral oxides (black), respectively, whereas white pigments are characterized by calcite, ghelenite and gypsum.     

Introduction: Critical Agrarian Studies in Theory and Practice

In this introductory article we argue for renewed attention to life and labor on and of the land—or what we call the field of Critical Agrarian Studies. Empirically rich and theoretically rigorous studies of humanity's relationship to “soil” remain essential not just for historical analysis but for understanding urgent contemporary crises, including widespread food insecurity, climate change, the proliferation of environmental refugees, growing corporate power and threats to biodiversity. The article introduces an innovative and varied collection of works in Critical Agrarian Studies and also examines the intellectual and political history of this broader field.