Developing and Sequencing Community Engagement and Experiential Education: A Case Study of Urban Geography Teaching and Research

Community engagement curricula and course design can provide substantial experiences for both community members and participating students. Using a case study approach, this research focuses on four steps in this process: initial community relationship forming, engaging in community service, transitioning to civic engagement, and developing a community-based research program. Narrative examples from student course evaluations position these community-based experiences as transformative for multiple parties. Institutional structures are presented as helpful entrees to engagement for students, while noting that community relationships provide contextualized, powerful, and meaningful relationships, supporting recommendations for emerging and existing community engagement programs.     

传承和发扬人文与经济地理学前辈的精神和知识体系——人文与经济地理学青年论坛综述

2018年1月27-28日,人文与经济地理学青年论坛暨第二届中国科学院区域可持续发展分析与模拟重点实验室青年论坛在北京国家会议中心成功举办。论坛以“人文与经济地理学的传承与创新：青年学者的责任与行动”为主题,来自全国100余家高校和研究机构从事人文与经济地理学相关研究的青年学者370余人参会。这说明人文与经济地理学青年学者很活跃、有热情、有担当意识。青年学者要加强学习、传承和发扬人文与经济地理学前辈的精神和知识体系,迎接人文与经济地理学繁荣发展的新时代。     

Responses of Riverbed Particles to Geomorphologic Processes in Aeolian-Fluvial Action Area: A Case Study of the Heilaigou Basin in Inner Mongolia of China

The Heilaigou basin, located in the Inner Mongolia of China, is predominantly influenced by the aeolian-fluvial actions, with complicated sediment transport conditions on the mainstream riverbed. In order to identify the relationship between sedimentary particles and geomorphic processes, mechanisms for the formation of characteristics of grain size composition were investigated by analyzing grain size parameters and external dynamic geomorphologic features. Firstly, the grain size parameters of the riverbed, stream power, maximum grain size of the wind-blown particles and HI values of the mainstream channel were calculated and analyzed, and they were used to establish multiple regression functions of grain size parameters in order to determine the effects of wind and river actions on particles. The results show that sediments in different reaches are formed in different environments: the upper stream is controlled by fluvial and aeolian processes; the sorting properties of riverbed sediments in the middle stream are worse than those in the upper stream since they are affected mainly by fluvial processes as indicated by the larger stream power there; and the particles on the downstream riverbed are likely contributed by the Kubuqi Desert. The size of particles on the riverbed depends on the hydrodynamic conditions, but is not significantly associated with the evolution of landform. Sorting is significantly related to both the hydrodynamic conditions and wind actions. Riverbed deposits brought in by winds likely become finer from the lower to the upper reaches, which are not coarser than 0.88f. Generally speaking, the stream power has a major effect on sedimentation characteristics of the riverbed, followed by wind power.     

“一带一路”战略的河南行动

"一带一路"战略是我国现代化建设与世界和平发展的一项世纪伟业。河南参与建设"一带一路"的行动,要以发挥优势、主动融入、服务大局为宗旨,把实施三大国家战略纳入"一带一路"框架内。构建全方位对外开放的新格局、大格局,努力推动基础设施联通、能源资源拓展、金融保障构筑、经贸产业深化、人文交流强化等领域的筹划与协作。完善一个载体,打造四个体系,组建大郑州都市地区,形成我国内陆腹地支撑"一带一路"的"中原板块"。     

干旱环境胁迫下农户适应性研究——基于民勤绿洲地区农户调查数据

适应能力及其评估框架为农户生计研究提供了一个新思路。本文在干旱环境背景下,借鉴农户可持续生计和适应能力相关理论,探讨民勤绿洲地区农户适应能力及适应行为。按照适应能力评估框架,构建农户适应能力评价指标体系,通过问卷和实地调查获取数据,在农户适应行为分类的基础上,测量不同适应类型农户的适应能力,分析影响农户适应类型的因素。结果表明：①从农户的适应行为来看,积极主动的适应行为选择较多,减少消费、参加社会保险等适应行为选择较少;农户适应类型中,综合适应型的比重最大,被动适应型最小。②农户的适应能力方面,各维度整体分布较为均衡,但自然能力和社会能力存在显著分异,而物质能力、金融能力、劳动能力和学习能力较均衡;不同农户适应类型中,综合适应型农户适应能力更稳定,务工主导型和被动适应型的稳定性较差。在适应能力六大维度中,物质能力在六大农户适应类型中所占比重最大,自然能力最小。③家庭物质资产、非农就业比重、社会网络、人均“退还关压”面积、受教育程度等适应能力指标对农户的适应行为选择具有显著影响。     

泡沫钻进中的腐蚀现象与泡沫发生器

泡沫钻进中有两个问题有待解决。第一是泡沫对钢铁具有明显的腐蚀作用。由于泡沫中有水和大量空气,而空气中含有氧。钢铁的腐蚀主要是水与氧的作用。在氧化锈蚀过程中发泡剂也起着重要作用。为此提出了防腐措施。第二是泡沫的发生。稳定泡沫的产生必须具备两个条件:物质条件和机械条件。没有发泡剂的加入不会产生稳定的泡沫。没有强有力的机械作用,气体进入不了液膜,也不会发泡。相应的措施是设专门的泡沫发生器。      

大型泊位设计中的水流问题——以宝钢马迹山港为例

本文以宝钢马迹山２５万吨级矿石中转港码头设计中所遇到的水流问题为例,通过对研究水域的水流性质以及泊位、船舶、水流三者之间关系的初步分析,认为水流尽管与风、浪一样不致船舶结构破坏,但一定时段内却可能对其靠泊造成困难,而水流作用于系泊中船舶并传递给码头结构物的荷载,以及水流与波浪相互作用使得波流要素改变则是设计中必需考虑的。最后,作者对港口设计和运作提出建议,以期相类似水深流急地区建设大型泊位时能有所借鉴。     

红树植物次生木质部的结构与进化

研究了红树科Rhizophoraceae的木榄Bruguiera gymnorrhiza、海莲Bruguiera sexangula、角果木Ceriops tagal和秋茄Kandelia candel;马鞭草科Verbenaceae的白骨壤Avicennia marina;紫金牛科Mysinaceae的桐花树Aegiceras corniculatum和海桑和Sonneratiaceae的海桑Sonneratia caeseolaria次生木质部的结构与进化关系,红树科植物的次生木质部结构比马鞭草科、紫金牛科和海桑科的植物原始;红树科中的竹节树属Carallia和山红树属Pellacalyx为陆生的非红树植物,它们次生木质部结构比海生的红树料红树植物木榄属、秋茄属、角果木属更为进化,即导管为单穿孔、管间纹孔式为互利式纹孔.单穿孔的导管存在,是长期的进化过程中,遇到干旱环境而产生的特化现象,而海生红树科植物进入海滩沼译后,木质部仍具有原始性状.     

Mechanisms of the southward translation of meddies

Meddies are warm and saline anticyclonic eddies found at the mid-depth of the Mediterranean Outflow in the Eastern North Atlantic. They are observed to move almost southward at average speeds as high as 1.3±0.2 cm s⁻¹. This paper examines a mechanism which accelerates this curious translation to a reasonable speed when combined with nonlinearity and a suitable vertical eddy structure. This mechanism is thepseudo-topographic β effect due to the westward decrease in the thickness of the mid-layer induced by the surface southward mean current. The linear dispersion relation including this effect is shown to account for a quarter of the surface southward mean current or a fifth of the observed southward translation of meddies. Three-layer quasi-geostrophic experiments reveal that the surface southward mean current certainly enhances the southward translation velocity of meddies to a speed in agreement with observation, if the meddy has a current structure of plausible intensity and vertical coherence. In the light of the current-induced pseudo-topographic β effect, previous hypotheses are also re-examined through dynamic arguments together with numerical experiments; they are suggested to have some difficulty either in dynamics or in correspondence with observation. Thus the nonlinear effect due to secondary eddies combined with thecurrent-induced pseudo-topographic β effect is the most likely mechanism responsible for the rapid southward translation of meddies among those examined in the paper.     

A pair of Langmuir cells in two laboratory tanks (II) on generation mechanism

Vertical and cross-wind profiles of mean currents were measured systematically in vertical cross-sections of two wind-wave tanks with aspect ratios of order one to study the secondary flow in the tanks. A pair of Langmuir cells turned out to be driven by a close combination of the pressure gradient along the tank and the side-wall effects. That is, part of the adverse pressure gradient produced a parabolic cross-wind profile with the smallest downwind current at the centerline and the largest current along the two sidewalls. As a result, upwelling occurred in the center zone where the return flow was strongest, probably because of the entrainment action of the wind-driven current. In order to compensate for this upwelling, downwelling occurred along the two side-walls from the flow continuity. The resulting vertical circulation formed a pair of Langmuir circulations across the span and served to maintain the parabolic profile formed by the pressure gradient. A positive feedback mechanism is thus found between the primary and secondary circulations through upwelling of the return flow in the center zone. Vertical shears of the span-averaged downwind current measured in two tanks were found to be systematically different from each other. This difference seems to depend on the magnitude of the advective Reynolds stresses in the two tanks.