3D geometric structures and biological activity: Application to microbial soil organic matter decomposition in pore space

During the past 10 years, soil scientists have started to use 3D Computed Tomography in order to gain a clearer understanding of the geometry of soil structure and its relationships with soil properties. We propose a geometric model for the 3D representation of pore space and a practical method for its computation. Our basic idea consists in representing pore space using a minimal set of maximal balls (Delaunay spheres) recovering the shape skeleton. In this representation, each ball could be considered as a maximal local cavity corresponding to the “intuitive” notion of a pore as described in the literature. The space segmentation induced by the network of balls (pores) was then used to spatialize biological dynamics. Organic matter and microbial decomposers were distributed within the balls (pores). A valuated graph representing the pore network, organic matter and distribution of micro-organisms was then defined. Microbial soil organic matter decomposition was simulated by updating this valuated graph. The method was implemented and tested using real CT images. The model produced realistic simulated results when compared with data in the literature in terms of the water retention curve and carbon mineralization. A decrease in water pressure decreased carbon mineralization, which is also in accordance with findings in the literature. From our results we showed that the influence of water pressure on decomposition is a function of organic matter distribution in the pore space. As far as we know, this is the approach to have linked pore space geometry and biological dynamics in a formal way. Our next goal will be to compare the model with experimental data of decomposition using different soil structures, and to define geometric typologies of pore space shape that can be attached to specific biological and dynamic properties.     

网络分析法在城市绿网优化中的应用

2005-2020年天津总规之绿地系统规划(总规绿网),由于缺乏绿网优化配置,其生态效益仍将不尽如人意。为此,采用图论和网络分析法(ANP),构建、评价了4个具有不同连接度和生态水平的绿网方案。ANP模型计算结果表明,绿网4最大化地利用现状和潜在廊道、连接各斑块,效益排序最优,成本次优,综合效益最高,且敏感度分析证明当效益与成本比大于0.25时,首位排序稳定。协调土地利用与交通等相关规划要素,给出基于网络4的绿地系统规划方案,为总规绿网优化提供依据。ANP适用于多目标、多因子、多方案决策,可解决以往网络指数与景观指数分离问题,实现不同顶点位置的网络评价,是绿网优化的有力工具。     

Modeling Habitat Suitability for Complex Species Distributions by Environmental-Distance Geometric Mean

This paper presents a new habitat suitability modeling method whose main properties are as follows: (1) It is based on the density of observation points in the environmental space, which enables it to fit complex distributions (e.g. nongaussian, bimodal, asymmetrical, etc.). (2) This density is modeled by computing the geometric mean to all observation points, which we show to be a good trade-off between goodness of fit and prediction power. (3) It does not need any absence information, which is generally difficult to collect and of dubious reliability. (4) The environmental space is represented either by an expert-selection of standardized variables or the axes of a factor analysis [in this paper we used the Ecological Niche Factor Analysis (ENFA)].We first explain the details of the geometric mean algorithm and then we apply it to the bearded vulture (Gypaetus barbatus) habitat in the Swiss Alps. The results are compared to those obtained by the median algorithm and tested by jack-knife cross-validation. We also discuss other related algorithms (BIOCLIM, HABITAT, and DOMAIN). All these analyses were implemented into and performed with the ecology-oriented GIS software BIOMAPPER 2.0.The results show the geometric mean to perform better than the median algorithm, as it produces a tighter fit to the bimodal distribution of the bearded vulture in the environmental space. However, the median algorithm being quicker, it could be preferred when modeling more usual distribution.     

我国企业组织与可持续发展

本文根据可持续发展思想和企业组织空间结构理论，探讨了我国企业组织实施可持续发展战略的途径，认为我国企业组织应注重企业经济适度高速增长，提出可持续发展战略在“企业组织层面”和“地域企业层面”上进行“纵向”和“横向”实施的途径。     

亚太区域持续发展与空间技术合作

随着世界经济多极化与区域重新组合,亚太地区经济日益繁荣,异常活跃。利用空间技术进行资源勘探与开发、环境监测与保护的需求不断增长。特别是巴西召开世界环境与发展大会之后,提出了《21世纪议程》,亚太地区许多国家和国际组织采取新的政策,积极参与近几年对空间应用的国际合作。反映了充分发挥现有空间应用潜力、加强空间应用、促进区域社会经济持续发展的共同愿望。     

城市再生空间的开发利用——开拓城市绿化新空间

随着城市化程度的提高，再生空间所占比重越来越大。充分开发利用这些空间，因空制宜地进行不同形式的绿化，可大大提高城市绿化水平和景观质量，改善城市环境状况，对卫生城市和园林城市的达标起积极作用。     

大空间建筑火灾中烟气温度计算模型的比较

基于区域模型和场模型的计算方法，分别计算了大空间建筑火灾的热烟气温度与时间的关系曲线（T-t曲线）。通过比较计算结果可得出：区域模型计算方法对大空间建筑火灾热烟气的填充规律及填充过程中的温度预测具有足够的精度；但随着热烟气层的下降，当下层冷空气逐渐减少至80％被热烟气所取代时，该计算方法对烟气温度预测的准确性不太高。建议对大空间建筑火灾中结构反应全过程分析的T-t曲线，采用基于场模型的计算方法，或者，对基于区域模型的T-t曲线进行修正。     

可视化灾害数字仿真重构理论及实证研究--灾害本质解析及仿真理论可行性分析

可视化灾害数字仿真重构理论研究，不仅可以实现对灾害空问数据进行有效的集成管理和时空分析，而且为灾害的防治、应急管理和工程论证等提供可靠的依据，是解决灾害实验的危险性和不可重复性的最佳途径。本文在综述灾害防治手段及相关研究进展的基础上，明确了灾害的定义和特征，论述了灾害的分类与分级方法，研究了孕灾环境、承灾体和致灾因子的成灾模式，提出了灾害空间的涵义。在灾害本质解析的基础上，提出灾害数字仿真重构理论的概念，并论证了理论的可行性，为进一步的研究创造了条件。     

我国城市地下空间立法的特点、问题及改进

合理开发利用城市地下空间,把握好城镇化战略着力点,是我国实现新时代高质量发展的客观要求.目前,我国城市地下空间立法渐成体系,表现为中央和地方立法并进、综合与专项立法互补的特点,尤其是地方政府先行先试、积极探索,为城市地下空间开发利用提供了具有可操作性的规则.结合《民法典》《城市地下空间开发利用管理规定》以及现行有效的2...     

沈阳市不同粒径区间街道灰尘中Pb的空间分布特征研究

研究了沈阳市一环及其内主要街道在不同粒径区间灰尘中Pb的空间分布特征,共采集61个样品。分别测定了灰尘在100～125,63～100和小于63μm这3个粒径区间中Pb的含量。结果表明：此3个粒径区间中Pb含量相近,63—100μm粒径中Pb含量稍高;铁西区污染程度处于市内5区之首。