Nano-mechanical Properties and Pore-Scale Characterization of Different Rank Coals   总被引：1，自引：0，他引：1  

Zhang  Yihuai  Lebedev  Maxim  Smith  Gregory  Jing  Yu  Busch  Andreas  Iglauer  Stefan 《Natural Resources Research》2020,29(3):1787-1800

Characterization of coal micro-structure and the associated rock mechanical properties are of key importance for coal seam exploration, coal bed methane development, enhanced coal bed methane production and CO₂ storage in deep coal seams. Considerable knowledge exists about coal chemical properties, but less is known about the nanoscale to the micro-scale structure of coals and how they change with coal strength across coal ranks. Thus, in this study, 3D X-ray micro-computed tomography (with a voxel size of 3.43 µm) and nano-indentation tests were conducted on coal samples of different ranks from peat to anthracite. The micro-structure of peats showed a well-developed pore system with meso- and micro-pores. The meso-pores essentially disappear with increasing rank, whereas the micro-pores persist and then increase past the bituminous rank. The micro-fracture system develops past the peat stage and by sub-bituminous ranks and changes into larger and mature fracture systems at higher ranks. The nano-indentation modulus showed the increasing trend from low- to high-rank coal with a perfect linear relationship with vitrinite reflectance and is highly correlated with carbon content as expected.

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The impact of interactive visualization on trade-off-based geospatial decision-making     

Goran Milutinović  Ulla Ahonen-Jonnarth  Stefan Seipel  Sven Anders Brandt 《International journal of geographical information science》2019,33(10):2094-2123

In a previous work we developed GISwaps, a novel method for geospatial decision-making based on Even Swaps. In this paper, we present the results of an evaluation of a visualization framework integrated with this method, implemented within a decision support system. This evaluation is based on two different studies. In the quantitative study, 15 student participants used GISwaps with no visual features, and 15 participants used GISwaps with the integrated visual framework, as the tool in a solar farm site location case study. The results of the quantitative evaluation show positive impact of the visualization in terms of increased coherency in trade-offs. The results also show a statistically significant difference in average trade-off values between the groups, with users from the non-visual group setting on average 20% higher trade-off values compared with the users in the visual group. In the qualitative study, we had one expert in GIS, two experts in decision-making and two experts in solar energy as a focus user group. Data in this study were obtained by observations and semi-structured interviews with the participants. The impact of the visualization framework was assessed positively by all participants in the expert group.  相似文献   

Towards a typology of urban centers and subcenters – evidence from German city regions     

Angelika Krehl  Stefan Siedentop 《Urban geography》2019,40(1):58-82

This study aims to characterize urban spatial structure with respect to its multidimensionality. Using an encompassing data set of socioeconomic variables, as well as variables pertaining to the built environment, accessibility and land use, we suggest a quantitatively based urban (sub-) center typology. The fine-grained spatial scale of 1 km² grid cells permits a higher spatial resolution than that used in most previous studies. Our suggested typology is two-layered: a “macro layer” based on cluster analyses sheds light on urban spatial configurations. A corresponding threshold-based “micro layer” identifies distinctive types of centers and subcenters at the local level. The application of this multi-scale and multivariate typology to four German city regions indicates both the core cities’ morphological dominance and the formation of subcenters with distinct profiles of regional economic importance, land use patterns and urban form. However, a substantial degree of spatial dispersion is observed because much activity is located in non-central locations.  相似文献   

Marine ecosystem-based management in the Southern Cone of South America: Stakeholder perceptions and lessons for implementation     

Stefan Gelcich  Omar Defeo  Oscar Iribarne  Graciano Del Carpio  Random DuBois  Sebastian Horta  Juan Pablo Isacch  Natalio Godoy  Pastor Coayla Pealoza  Juan Carlos Castilla 《Marine Policy》2009,33(5):801-806

Ecosystem-based management (EBM) has recently received considerable attention. However, examples of empirical approaches to marine EBM are scarce. Therefore, empirical information on the presence of EBM elements within existing policies and the way they may provide settings and lessons for EBM implementation is timely. This study analyses stakeholders’ perceptions on the existence of EBM principles in current marine management practices and policies, and how they determine perceptions for success and satisfaction regarding coastal management within selected case studies drawn from four developing countries in the Southern Cone of South America. Patterns of response across study sites show that although EBM principles as such are not explicitly included in management/conservation plans, there are policies (mainly local), which generate conditions for more explicit inclusion of them. These are based on participatory bottom-up planning, place-based management and consensus reaching: all elements included within the theoretical literature on EBM implementation.  相似文献   

A MATLAB toolbox for attitude determination with GPS multi-antenna systems     

Zhen Dai  Stefan Knedlik  Otmar Loffeld 《GPS Solutions》2009,13(3):241-248

In this paper a MATLAB toolbox for determining the attitude of a rigid platform by means of multiple non-dedicated antennas using global positioning system is presented. The programs embedded in this toolbox cover the RINEX data analysis, single point positioning, differential positioning, coordinate conversion, attitude determination, and other auxiliary functions. After forming the baselines through double-differenced (carrier phase smoothed) code observables, the attitude parameters are obtained by applying the direct attitude computation and the least squares attitude estimation. The theoretical background is summarized, and some hints regarding the software implementation are given in the paper. Moreover, improvements yielding an expanded functionality are proposed.

Zhen DaiEmail:

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Impact of the arc length on GNSS analysis results   总被引：3，自引：3，他引：0  

Simon Lutz  Michael Meindl  Peter Steigenberger  Gerhard Beutler  Krzysztof Sośnica  Stefan Schaer  Rolf Dach  Daniel Arnold  Daniela Thaller  Adrian Jäggi 《Journal of Geodesy》2016,90(4):365-378

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A dimensional analysis to quantify the thermal budget around lithospheric‐scale shear zones          下载免费PDF全文

Sylvia Duprat‐Oualid  Philippe Yamato  Stefan M. Schmalholz 《地学学报》2015,27(3):163-168

The thermal evolution around shear zones is controlled by three major thermal processes: diffusion, advection and shear heating. We present a dimensional analysis to quantify, to first‐order, the relative contributions of these three processes to the thermal evolution around lithospheric‐scale shear zones. We consider 11 parameters that control the kinematics, the three‐dimensional (3‐D) geometry, the initial thermal structure and the average strength of the shear zone. Three dimensionless parameters are presented to quantify the relative contributions of the three thermal processes. We validate the dimensional analysis with 2‐D thermo‐kinematic numerical models. The applicability of the dimensional analysis to any kind of shear zone (i.e. thrust, normal‐slip and strike‐slip shear zones) makes it a useful tool that is complementary to previous numerical and analytical studies. Finally, thrust‐type shear zones are used to illustrate how the three thermal processes control the thermal evolution.  相似文献   

Contributions of soil moisture interactions to climate change in the tropics in the GLACE–CMIP5 experiment     

Wilhelm May  Arndt Meier  Markku Rummukainen  Alexis Berg  Frederique Chéruy  Stefan Hagemann 《Climate Dynamics》2015,45(11-12):3275-3297

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Spatio‐temporal controls of snowmelt and runoff generation during rain‐on‐snow events in a mid‐latitude mountain catchment          下载免费PDF全文

Jakob Garvelmann  Stefan Pohl  Markus Weiler 《水文研究》2015,29(17):3649-3664

A network of 30 standalone snow monitoring stations was used to investigate the snow cover distribution, snowmelt dynamics, and runoff generation during two rain‐on‐snow (ROS) events in a 40 km² montane catchment in the Black Forest region of southwestern Germany. A multiple linear regression analysis using elevation, aspect, and land cover as predictors for the snow water equivalent (SWE) distribution within the catchment was applied on an hourly basis for two significant ROS flood events that occurred in December 2012. The available snowmelt water, liquid precipitation, as well as the total retention storage of the snow cover were considered in order to estimate the amount of water potentially available for the runoff generation. The study provides a spatially and temporally distributed picture of how the two observed ROS floods developed in the catchment. It became evident that the retention capacity of the snow cover is a crucial mechanism during ROS. It took several hours before water was released from the snowpack during the first ROS event, while retention storage was exceeded within 1 h from the start of the second event. Elevation was the most important terrain feature. South‐facing terrain contributed more water for runoff than north‐facing slopes, and only slightly more runoff was generated at open compared to forested areas. The results highlight the importance of snowmelt together with liquid precipitation for the generation of flood runoff during ROS and the large temporal and spatial variability of the relevant processes. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

Managed aquifer recharge(MAR)applications in China–achievements and challenges          下载免费PDF全文

Jin-xing Guo  Zhi-ping Li  Catalin Stefan 《地下水科学与工程》2022,10(1):57-69

Groundwater is of fundamental significance for human society,especially in semi-arid areas in China.However,due to the fast social and economic development,China has been suffering from the shortage of water resource.In this situation,managed aquifer recharge(MAR)was considered to be an effective measure for the sustainable management of groundwater resources.Since 1960 s,China successfully implemented many MAR schemes for different purposes such as restoration of groundwater tables,prevention of seawater intrusion,increasing urban water supplies and controlling land subsidence.From those successful experiences China developed a scientific and applicable system to implement MAR project.However,there were still many challenges in this field,for example,treated waste water had been barely used for recharge.The present review summarized the achievements in MAR applications in China as well as the associated challenges within the past 55 years before the year 2016.  相似文献