Strength Anisotropy of Berea Sandstone: Results of X-Ray Computed Tomography,Compression Tests,and Discrete Modeling     

Kwang Yeom Kim  Li Zhuang  Hwayoung Yang  Hanna Kim  Ki-Bok Min 《Rock Mechanics and Rock Engineering》2016,49(4):1201-1210

  相似文献   

Assessing the ambition of post-2020 climate targets: a comprehensive framework     

Niklas Höhne  Hanna Fekete  Michel G.J. den Elzen  Andries F. Hof  Takeshi Kuramochi 《Climate Policy》2018,18(4):425-441

One of the most fundamental questions surrounding the new Paris Agreement is whether countries’ proposals to reduce GHG emissions after 2020 are equally ambitious, considering differences in circumstances between countries. We review a variety of approaches to assess the ambition of the GHG emission reduction proposals by countries. The approaches are applied illustratively to the mitigation part of the post-2020 climate proposals (nationally determined contributions, or NDCs) by China, the EU, and the US. The analysis reveals several clear trends, even though the results differ per individual assessment approach. We recommend that such a comprehensive ambition assessment framework, employing a large variety of approaches, is used in the future to capture a wide spectrum of perspectives on ambition.

POLICY RELEVANCE

Assessing the ambition of the national climate proposals is particularly important as the Paris Agreement asks for regular reviews of national contributions, keeping in mind that countries raise their ambition over time. Such an assessment will be an important part of the regular global stocktake that will take place every five years, starting with a ‘light’ version in 2018. However, comprehensive methods to assess the proposals are lacking. This article provides such a comprehensive assessment framework.  相似文献   

Could Cohesion Policy push EU climate efforts?     

Michal Nekvasil  Bedřich Moldan 《Climate Policy》2018,18(1):129-139

The main purpose of this article is to evaluate the extent to which the Cohesion Policy of the EU contributes to its climate change mitigation effort. While climate change mitigation and the EU Cohesion Policy have been both thoroughly studied theoretically, the novelty of the present article lies in an analysis of their mutual relationship. Also, a unique feature of this research is an analysis of the contribution of the Cohesion Policy to climate change mitigation over a period of 20 years, including a comparison of the three last programming periods (2000–2006, 2007–2013 and 2014–2020). The results of this research suggest that, while the beginning of the new millennium saw the Cohesion Policy neglecting the issue of climate change mitigation, the current programming period (2014–2020) placed it among its key priorities. This conclusion is supported by a comprehensive set of data on five selected indicators. This article also displays the results against the perspective of the overall climate change mitigation objectives of the EU.

POLICY RELEVANCE

The present article shows how a policy, which used to be considered rather distant from climate change, progressively adopted climate change mitigation as one of its principal objectives. As such, it provides a practical guidance on the integration of climate change mitigation in other policy areas, which may be applied not only in a supranational organisation but also on a national, regional or local level.  相似文献   

Alkalic parental magmas for chassignites?     

Hanna NEKVASIL  Justin FILIBERTO  Francis M. McCUBBIN  Donald H. LINDSLEY 《Meteoritics & planetary science》2007,42(6):979-992

Abstract Detailed analysis of cumulate and melt inclusion assemblages in the chassignites provide important constraints on the nature of the melt trapped as inclusions in cumulus olivine (and, by extension, parental magma compositions), the pressures of crystallization, and magmatic volatile contents. These mineral assemblages show strong similarities to the experimental fractionation assemblages that produce the sodic silica‐saturated alkalic lavas on Earth (e.g., Ascension Island, Azores, the Nandewar volcano of Australia). The experimental assemblages were produced from silica‐saturated hawaiite at pressures above 4.3 kbar with dissolved water contents above 0.5 wt%. Such pressures are consistent with Ti:Al ratios of the melt‐inclusion pyroxenes in the Chassigny meteorite. Pyroxene compositions suggest early high crystallization temperatures and thus relatively low initial water and F contents. Feldspars indicate that melt evolution proceeded to rhyolite compositions both within the interstices of the cumulate olivine and within the melt inclusions, even though rhyolitic glass is only found within olivine‐hosted polyphase melt inclusions. The observed rhyolite glass is compositionally similar to the alkali‐rich rhyolite of Ascension Island which is produced experimentally by crystallization of hawaiite. It is proposed that the melt trapped in cumulus olivine of the Chassigny dunite was similar to a terrestrial silica‐saturated hawaiite, while that trapped in olivine of the Northwest Africa (NWA) 2727 dunite was less evolved, perhaps mildly alkalic basalt. Melts similar to terrestrial intra‐plate tholeiite could be parental to the cumulus minerals and evolve upon crystallization at pressures above 4.3 kbar and water contents above ?0.4 wt% to mildly alkalic basalt, silica‐saturated hawaiite, and alkali‐rich rhyolite. The melt inclusion assemblages are inconsistent with either crystallization of a low‐Al, high‐Fe basalt, or low‐pressure crystallization of a terrestrial‐like tholeiite.  相似文献   

Aesthetic justice and urban planning: Who ought to have the right to design cities?*     

Hanna Mattila 《GeoJournal》2002,58(2-3):131-138

This paper brings together two diverse approaches to urban planning. The first approach views planning as a means to distribute goods or welfare in society, and therefore considers the promotion of social justice to be the central objective of planning. The second approach highlights the role of planning as a means to produce aesthetically pleasing everyday surroundings. I will explore the concepts of `aesthetic welfare' and `aesthetic justice' developed by the philosopher Monroe Beardsley, and argue that an aesthetically pleasing environment is an important source of aesthetic welfare in society. My contention, then, is that the fair distribution of this welfare should be one of the objectives of public planning policies. This objective, however, is difficult to achieve, since the question cannot only concern the distribution of the aesthetically good environment. This is because there often is no agreement on the criteria for the aesthetically good environment. Thus, I will eventually reject the idea of aesthetic justice as distributive justice that Beardsley advocates. Instead, I will turn to some contemporary theories of justice that question the model of distributive justice, arguing that theories of justice should go beyond the distribution of goods, and encompass also the conception and production of goods. Thus, as I will maintain, aesthetic justice will be eventually best promoted by opening the aesthetic dimension of urban planning (among other dimensions of it) to public participation.  相似文献   

Automated facies identification by Direct Push-based sensing methods (CPT,HPT) and multivariate linear discriminant analysis to decipher geomorphological changes and storm surge impact on a medieval coastal landscape     

Hanna Hadler  Andreas Vött  Timo Willershäuser  Dennis Wilken  Ruth Blankenfeldt  Claus von Carnap-Bornheim  Kurt Emde  Peter Fischer  Ulf Ickerodt  Stefanie Klooß  Bente Majchczack  Lea Obrocki  Wolfgang Rabbel 《地球表面变化过程与地形》2021,46(15):3228-3251

In ad 1362, a major storm surge drowned wide areas of cultivated medieval marshland along the north-western coast of Germany and turned them into tidal flats. This study presents a new methodological approach for the reconstruction of changing coastal landscapes developed from a study site in the Wadden Sea of North Frisia. Initially, we deciphered long-term as well as event-related short-term geomorphological changes, using a geoscientific standard approach of vibracoring, analyses of sedimentary, geochemical and microfaunal palaeoenvironmental parameters and radiocarbon dating. In a next step, Direct Push (DP)-based Cone Penetration Testing (CPT) and the Hydraulic Profiling Tool (HPT) were applied at vibracore locations to obtain in situ high-resolution stratigraphic data. In a last step, multivariate linear discriminant analysis (LDA) was successfully applied to efficiently identify different sedimentary facies (e.g., fossil marsh or tidal flat deposits) from the CPT and HPT test dataset, to map the facies' lateral distribution, also in comparison to reflection seismic measurements and test their potential to interpolate the borehole and CPT/HPT data. The training dataset acquired for the key site from coring and DP sensing finally allows an automated facies classification of CPT/HPT data obtained elsewhere within the study area. The new methodological approach allowed a detailed reconstruction of the local coastal landscape development in the interplay of natural marsh formation, medieval land reclamation and storm surge-related land losses.  相似文献   

Macroscopic impacts of cloud and precipitation processes in shallow convection     

Wojciech W. Grabowski  Joanna Slawinska  Hanna Pawlowska  Andrzej A. Wyszogrodzki 《Acta Geophysica》2011,59(6):1184-1204

This paper presents application of the EULAG model combined with a sophisticated double-moment warm-rain microphysics scheme to the model intercomparison case based on RICO (Rain in Cumulus over Ocean) field observations. As the simulations progress, the cloud field gradually deepens and a relatively sharp temperature and moisture inversions develop in the lower troposphere. Two contrasting aerosol environments are considered, referred to as pristine and polluted, together with two contrasting subgridscale mixing scenarios, the homogeneous and the extremely inhomogeneous mixing. Pristine and polluted environments feature mean cloud droplet concentrations around 40 and 150 mg^?1, respectively, and large differences in the rain characteristics. Various measures are used to contrast evolution of macroscopic cloud field characteristics, such as the mean cloud fraction, the mean cloud width, or the height of the center of mass of the cloud field, among others. Macroscopic characteristics appear similar regardless of the aerosol characteristics or the homogeneity of the subgrid-scale mixing.  相似文献   

Statistical simulations of the future 50-year statistics of cold-tongue El Niño and warm-pool El Niño     

Hanna Na  Bong-Geun Jang  Won-Moon Choi  Kwang-Yul Kim 《Asia-Pacific Journal of Atmospheric Sciences》2011,47(3):223-233

Recent extensive studies have suggested that the occurrence of warm-pool El Niño has increased since the late 1970s and will increase in future climate. Occurrence frequencies of cold-tongue and warm-pool El Niño have been investigated in the observational record (1980–2006) and in the future 50 years (2007–2056) based on 100 synthetic SST datasets with estimates of statistical confidence. In the observational record, 80% of the warm-pool El Niño occurred since 1980 over a period of 27 years; only 20% of the warm-pool El Niño occurred prior to 1980 over a period of 110 years. The 100 synthetic datasets, on average, produce 142 months of cold-tongue El Niño in 2007–2056 as opposed to an average 107 months in the same length of the observational data; this is a 20.7% increase in the occurrence of cold-tongue El Niño compared with the observational period. Warm-pool El Niño occurred for 112 months in 2007–2056 as opposed to an average occurrence of 42 months in the observational record; this is 2.5 times the occurrence frequency in the 1980–2006 period in the synthetic datasets. As a result, occurrence frequencies of cold-tongue and warm-pool El Niño in the period of 2007–2056 become quite comparable to each other in the synthetic datasets. It is expected in the next 50 years that warm-pool El Niño will be nearly as frequent as cold-tongue El Niño.  相似文献   

Composition and solubility of precipitated copper(II) arsenates     

Hanna Nelson  Andrey Shchukarev  Staffan Sjberg  Lars Lvgren 《Applied Geochemistry》2011,26(5):696-704

Equilibrium reactions involving Cu(II) and As(V) have been studied with respect to formation of complexes in aqueous solutions as well as formation of solid phases. Potentiometric titrations performed at 25 °C (I = 0.1 M Na(Cl)) and at different Cu to As ratios gave no evidence for the existence of Cu(II) arsenate complexes in solution below the pH of the precipitation boundaries (pH ≈ 4), irrespective of the Cu to As ratio and pH. Mixing of solutions of Cu(II) and As(V) at different proportions and adjusting pH to values ranging from 4 to 9 resulted in precipitation of five different solid phases. The elemental composition of the solids was determined using X-ray Photoelectron Spectroscopy, and Environmental Scanning Microscopy-Field Emission Gun equipped with an energy dispersive spectroscopy detector. The average Cu/As ratio was determined by dissolving the solids. Total soluble concentrations of the components Cu(II) and As(V), as well as the basicity of the solid phases were determined by analysis of aqueous solutions. Based upon these experimental data the stoichiometric composition of the solid phases and their stability were determined. The resulting equilibrium model includes the solid phases Cu₃(AsO₄)₂, Cu₃(AsO₄)(OH)₃, Cu₂(AsO₄)(OH), Cu₅Na(HAsO₄)(AsO₄)₃ and Cu₅Na₂AsO₄)₄, where Cu₅Na(HAsO₄)(AsO₄)₃ and Cu₅Na₂(AsO₄)₄ have not been reported previously. In 0.1 M Na(Cl), Na⁺ was found to be a significant component in two of the solid phases. The Cu₅Na₂(AsO₄)₄ was formed in weakly alkaline conditions with pNa < 2.5. Stability constants for all solid phases have been determined. Distribution diagrams as well as predominance area (pNa-pH) diagrams are presented to illustrate stability fields of the different solid phases.  相似文献   

Quasi-geostrophic shallow-water vortex–patch equilibria and their stability     

Hanna Płotka  David G. Dritschel 《地球物理与天体物理流体动力学》2013,107(6):574-595

We examine the equilibrium form, properties, stability and nonlinear evolution of steadily-rotating simply-connected vortex patches in the single-layer quasi-geostrophic model of geophysical fluid dynamics. This model, valid for rotating shallow-water flow in the limit of small Rossby and Froude numbers, has an intrinsic length scale L _D called the “Rossby deformation length” relating the strength of the stratification to that of the background rotation. Here, we generate steadily-rotating vortex equilibria for a wide range of γ?=?L/L _D , where L is the typical horizontal length scale of the vortex. We vary both γ (over the range 0.02?≤?γ?≤?10) and the vortex aspect ratio λ (over the range 0?<?λ?<?1). We find two modes of instability arising at sufficiently small aspect ratio λ?<?λ _c (γ): an asymmetric (dominantly wave 3) mode at small γ (or large L _D ) and a symmetric (dominantly wave 4) mode at large γ (or small L _D ). At marginal stability, the asymmetric mode dominates for γ???3, while the symmetric mode dominates for γ???3. The nonlinear evolution of weakly-perturbed unstable equilibria results in major structural changes, in most cases producing two dominant vortex patches and thin, quasi-passive filaments. Overall, the nonlinear evolution can be classified into three principal types: (1) vacillations for a limited range of aspect ratios λ when 5?≤?γ?≤?6, (2) filamentation and a single-dominant vortex for γ???1, and (3) vortex splitting – asymmetric for 1???γ???4 and symmetric for γ???4.  相似文献