Mg gas infiltration for the fabrication of MgB2 pellets using nanosized and microsized B powders

MgB₂ superconductor pellets were synthesized through Mg gas infiltration method using nanosized- and microsized B powders. There was a marked difference in the superconducting properties of the two samples, particularly in the pinning force and dominant pinning mechanism. The microstructures of the samples were observed using HR-TEM and STEM-HAADF, and the results showed that the primary reason for the difference in the superconducting properties is the distribution of the nanosized second-phase particle MgO. Additionally, a feasible reaction model for the Mg gas infiltration method was established. Compared to the Mg liquid infiltration method, the gas infiltration showed better penetrability ability with a small amount of residual Mg. This study presents a novel synthesis process to fabricate an MgB₂ pellet with superior density and superconducting properties. This method can be used in multiple applications such as superconducting bearings, compact superconductor magnets, and magnetic shielding.     

广州市传统滨水动态人文景观的类型及空间格局

文章从风景园林学科的角度出发，对传统老广州曾经存在的地域人文景观里的典型——滨水动态人文景观进行了初步的全面整理，以日常型滨水动态人文景观和节庆型滨水动态人文景观为两种基本类型，总结梳理出超过25种滨水动态人文景观的主要类型，充分说明了广州市传统滨水动态人文景观的多样性和独特性。并以景观格局的理论视角分析了传统滨水动态人文景观在广州旧城的空间格局，分析得出其两个核心聚集区：以祭祀水神的仁威神庙为精神核心节点的呈圆形扩散的西关功能核心区和以长堤滨江段为中线的呈椭圆形扩散的珠江两岸功能核心区，并总结了促使这种人文景观发展与繁盛的历史经验，为广州地域文化景观的发扬及旧城更新工作提供借鉴。     

The application of decision support tools and the influence of local data in prioritizing barrier removal in lower Michigan,USA

Web-based decision support tools (DSTs) can be useful to facilitate decision-making processes for managing complex natural resource systems. However, the alignment of DSTs with the objectives in governmental policies or management plans and the influence of limited local data on the outputs of these tools may reduce the use of DSTs by decision makers. In this study, we examined the outcomes of web-based DSTs when different types of local data were incorporated and demonstrated a way to incorporate outputs from multiple DSTs or local inventories to benefit barrier removal decisions. Restoring habitat connectivity in rivers in northwest lower Michigan, USA, was used as a case study due to the abundance of local inventory data and web-based DSTs. We found that, when compared to prioritizations made using local data, some DSTs could produce similar outcomes (in barriers selected, cost, and the benefit for migratory fish) with limited data, but the trade-offs among users' objectives might influence the cost and effectiveness of DSTs' outputs. Improving the ability of DSTs to incorporate objectives consistent with policy and stakeholders' values (e.g., restore certain species or sedimentation control) across management scales can help close the gap between tool recommendations and management decisions while making the barrier removal prioritization process transparent and efficient.     

基于微气候模拟的武汉居住小区植被降温通风效应研究

在快速城镇化过程中，中国城市边缘区生态安全格局出现了自然生态与人文生态双重破坏的问题，研究基于复合生态平衡、生态空间活化、共建共享共赢的发展目标，提出以自然生态要素识别与敏感度分析、人文生态发展需求分析为基础，以自然与人文生态安全格局分区建构、复合生态空间耦合下的功能化发展指引为核心的城市边缘区生态安全格局重构方法框架，并结合铜陵城市边缘区——东湖地区规划建设展开理论应用与实践探索，为重构城市边缘区生态安全格局提供有益借鉴。     

私家园林中书斋的变迁

书斋是传统私家园林中书房、山斋的统称,而其功能又不止于文艺活动。书斋随着中国古代士大夫文人的人格和艺术体系的发展和完善而变迁,经历了汉魏六朝在私家园林中无特定选址、唐宋作为宅园的中心,以及明清蜷于园内一隅这3个主要演变阶段。至明清,书斋往往自成一处独立的小院,除了书房的基本功能以外,还可以独立承载园主人的日常起居、爱好雅嗜等,是明清文人宇宙观日益狭小的真实写照。     

跨行政区游憩空间柔性一体化研究 ——以高莱茵河沿岸地区为例

随着城市化与区域一体化的迅速发展,不同行政区之间的联动关系越来越紧密,这种联动关系在城市各功能空间的设计上有所体现,更渗透到了与市民息息相关的游憩空间建构之中。受制于行政管理等方面的原因,在跨行政区的游憩空间一体化实施过程中,往往会采取一系列柔性措施。以欧洲高莱茵河沿岸地区为研究对象,分析高莱茵河沿岸地区游憩空间的发展与现状,总结其游憩空间体系的构建特点,为中国跨城市河流沿岸的游憩空间柔性一体化建构提供策略与建议。     

Exploring place attachment and visions of nature of water-based recreationists: the case of the longitudinal dams

This study concerns an innovative project in the Dutch river Waal: the construction of longitudinal dams. By splitting the river into a main and secondary channel, these dams significantly impact the river landscape and the way it is used by different stakeholders. We report the results of a baseline study of the expectations local water-based recreationists (fishermen and boaters) had of the longitudinal dams before they were constructed. In addition, we explore their levels of place attachment, and use the visions of nature approach to elicit their lay philosophy of nature. We found that fishermen were more strongly attached to the area than boaters. Though expectations of the dams were generally negative, this differed significantly between fishermen and boaters, and between different dimensions of landscape change. We demonstrate the relevance of place attachment and visions of nature for understanding how recreationists perceive landscape change.     

中国农村土地整治生态景观建设策略

经济的不断发展对土地利用提出更高要求,为实现经济的可持续发展,需要增强土地整治工作成效,结合生态景观战略,以科学的举措来最大程度地发挥农村土地整治工作的效果。为此,文章结合我国土地整治生态景观中所出现的问题,提出了有效的建设策略,希望能够进一步协调生态与经济间的关系,实现二者的和谐发展。     

Effect of pore characteristics of fine lignite on particle density in separation medium

Effect of porosity on particle density was analyzed, which can be a potential factor of low efficiency. The porosity of particle with different densities was detected by surface area analyzer. In addition, Three-dimensional X-ray micro-imaging system (3D-XRM) was used to analyze the spatial distribution of internal pores. Results show that mesoporous and microporosity content increase with the increase of particle density. Three-dimensional distribution of pores shows that the pores are very rich and show a good connection. The density model including porosity and medium density was established, which shows the effect of medium filling on the change of particle density.     

不同煤阶煤孔隙特征及其吸附能力响应

我国是煤炭资源大国，煤层气储量规模相当可观，但煤储层又具有低孔、低渗的不足，照搬国外或常规石油天然气的开采程序和方法已被证实是走不通的。应结合实际，根据不同地质条件、不同煤阶的开采程序，进行孔隙特征研究。煤孔隙特征、连通性和吸附能力对煤层气开采影响尤为重要，为研究煤孔隙结构特征随煤变质程度的变化关系及其吸附能力的响应特点，采取不同地区不同变质程度煤样，进行压汞测试和等温吸附实验。实验结果表明，煤孔隙度和平均孔径均随变质程度增加呈现降低—升高—降低的趋势；煤中孔隙连通性随煤变质程度增加逐渐变差；随煤变质程度增加，其最大吸附能力也呈现降低—升高—降低的总体趋势。