Modelling the impact of pore space distribution on carbon turnover

2007 ◽  
Vol 208 (2-4) ◽  
pp. 295-306 ◽  
Author(s):  
K. Kuka ◽  
U. Franko ◽  
J. Rühlmann
Keyword(s):  
Pore Space ◽  
Space Distribution ◽  
Carbon Turnover ◽  
The Impact

scholarly journals Review of the relationship between aggregates geology and Los Angeles and micro-Deval tests

2021 ◽  
Vol 80 (3) ◽  
pp. 1963-1980
Author(s):  
Solomon Adomako ◽  
Christian John Engelsen ◽  
Rein Terje Thorstensen ◽  
Diego Maria Barbieri
Keyword(s):  
Los Angeles ◽  
Crystal Size ◽  
Grain Shape ◽  
Mechanical Performance ◽  
Pore Space ◽  
Construction Material ◽  
Engineering Properties ◽  
Coarse Grained ◽  
The Impact ◽  
The Relationship

AbstractRock aggregates constitute the enormous volume of inert construction material used around the globe. The petrologic description as igneous, sedimentary, and metamorphic types establishes the intrinsic formation pattern of the parent rock. The engineering properties of these rocks vary due to the differences in the transformation process (e.g. hydrothermal deposits) and weathering effect. The two most common mechanical tests used to investigate the performance of aggregates are the Los Angeles (LA) and micro-Deval (MD) tests. This study reviewed the geological parameters (including mineralogy, grain and crystal size, grain shape, and porosity) and the relationship to Los Angeles and micro-Deval tests. It was found that high content of primary minerals in rocks (e.g. quartz and feldspar) is a significant parameter for performance evaluation. Traces of secondary and accessory minerals also affect the performance of rocks, although in many cases it is based on the percentage. Furthermore, some studies showed that the effect of mineralogic composition on mechanical strength is not sufficient to draw final conclusions of mechanical performance; therefore, the impact of other textural characteristics should be considered. The disposition of grain size and crystal size (e.g. as result of lithification) showed that rocks composed of fine-grain textural composition of ≤ 1 mm enhanced fragmentation and wear resistance than medium and coarse grained (≥ 1 mm). The effect of grain shape was based on convex and concave shapes and flat and elongated apexes of tested samples. The equidimensional form descriptor of rocks somehow improved resistance to impact from LA than highly flat and elongated particles. Lastly, the distribution of pore space investigated by means of the saturation method mostly showed moderate (R = 0.50) to strong (R = 0.90) and positive correlations to LA and MD tests.

scholarly journals A model for coupled electro-hydro-mechanical processes in fine grained soils accounting for gas generation and transport

2010 ◽  
Vol 82 (1) ◽  
pp. 169-193 ◽  
Author(s):  
Claudio Tamagnini ◽  
Cristina Jommi ◽  
Fabio Cattaneo
Keyword(s):  
Pore Space ◽  
Transport Coefficients ◽  
Gas Production ◽  
Degree Of Saturation ◽  
Coupled Processes ◽  
Gas Generation ◽  
Fine Grained ◽  
Clayey Silt ◽  
Waste Containment Systems ◽  
The Impact

A theoretical and numerical model is developed for the quantitative analysis of coupled processes taking place in active waste containment systems, such as electrokinetic barriers or fences, in which alow intensity DC current is circulated across the clay barrier to move polar and non-polar contaminants. A novel feature of the proposed approach is the allowance for the presence of air in the pore space. Under unsaturated conditions, all transport coefficients involved in the electrokinetic process are strongly dependent on the degree of saturation of pore liquid. In order to assess the predictive capability of the proposed theory and to appreciate the impact of gas production at the electrodes, a series of numerical simulations of simple onedimensional electrokinetic tests have been performed. The results of the simulations compare reasonably well with data obtained from laboratory experiments performed on an illitic clayey silt. The numerical results indicate that the impact of gas production at the electrodes can be significant, even in low-intensity and short-duration treatments.

scholarly journals Gas Permeability of Cellulose Aerogels with a Designed Dual Pore Space System

Molecules ◽  
2019 ◽  
Vol 24 (15) ◽  
pp. 2688 ◽  
Author(s):  
Kathirvel Ganesan ◽  
Adam Barowski ◽  
Lorenz Ratke
Keyword(s):  
Porous Materials ◽  
Cell Walls ◽  
Gas Permeability ◽  
Pore Space ◽  
Nitrogen Adsorption ◽  
Space System ◽  
Fixed Amount ◽  
Hydrophilic Lipophilic Balance ◽  
Wide Range ◽  
The Impact

The gas permeability of a porous material is a key property determining the impact of the material in an application such as filter/separation techniques. In the present study, aerogels of cellulose scaffolds were designed with a dual pore space system consisting of macropores with cell walls composing of mesopores and a nanofibrillar network. The gas permeability properties of these dual porous materials were compared with classical cellulose aerogels. Emulsifying the oil droplets in the hot salt–hydrate melt with a fixed amount of cellulose was performed in the presence of surfactants. The surfactants varied in physical, chemical and structural properties and a range of hydrophilic–lipophilic balance (HLB) values, 13.5 to 18. A wide range of hierarchical dual pore space systems were produced and analysed using nitrogen adsorption–desorption analysis and scanning electron microscopy. The microstructures of the dual pore system of aerogels were quantitatively characterized using image analysis methods. The gas permeability was measured and discussed with respect to the well-known model of Carman–Kozeny for open porous materials. The gas permeability values implied that the kind of the macropore channel’s size, shape, their connectivity through the neck parts and the mesoporous structures on the cell walls are significantly controlling the flow resistance of air. Adaption of this new design route for cellulose-based aerogels can be suitable for advanced filters/membranes production and also biological or catalytic supporting materials since the emulsion template method allows the tailoring of the gas permeability while the nanopores of the cell walls can act simultaneously as absorbers.

Diagenetic patterns and pore space distribution along a platform to outer-shelf transect (Urgonian limestone, Barremian–Aptian, SE France)

2014 ◽  
Vol 306 ◽  
pp. 1-23 ◽  
Author(s):  
Philippe Léonide ◽  
François Fournier ◽  
John J.G. Reijmer ◽  
Hubert Vonhof ◽  
Jean Borgomano ◽  
...  
Keyword(s):  
Pore Space ◽  
Outer Shelf ◽  
Space Distribution ◽  
Se France

scholarly journals An advanced structural characterization of templated meso-macroporous carbon monoliths by small- and wide-angle scattering techniques

2020 ◽  
Vol 11 ◽  
pp. 310-322
Author(s):  
Felix M Badaczewski ◽  
Marc O Loeh ◽  
Torben Pfaff ◽  
Dirk Wallacher ◽  
Daniel Clemens ◽  
...  
Keyword(s):  
Neutron Scattering ◽  
Carbon Materials ◽  
Pore Space ◽  
Atomic Scale ◽  
Sorption Behavior ◽  
Wide Angle ◽  
Large Organic Molecule ◽  
Nanoscale Pore ◽  
Nanopore Structure ◽  
The Impact

This study is dedicated to link the nanoscale pore space of carbon materials, prepared by hard-templating of meso-macroporous SiO2 monoliths, to the corresponding nanoscale polyaromatic microstructure using two different carbon precursors wthat generally exhibit markedly different carbonization properties, i.e., a graphitizable pitch and a non-graphitizable resin. The micro- and mesoporosity of these monolithic carbon materials was studied by the sorption behavior of a relatively large organic molecule (p-xylene) in comparison to typical gas adsorbates (Ar). In addition, to obtain a detailed view on the nanopore space small-angle neutron scattering (SANS) combined with in situ physisorption was applied, using deuterated p-xylene (DPX) as a contrast-matching agent in the neutron scattering process. The impact of the carbon precursor on the structural order on an atomic scale in terms of size and disorder of the carbon microstructure, on the nanopore structure, and on the template process is analyzed by special evaluation approaches for SANS and wide-angle X-ray scattering (WAXS). The WAXS analysis shows that the pitch-based monolithic material exhibits a more ordered microstructure consisting of larger graphene stacks and similar graphene layer sizes compared to the monolithic resin. Another major finding is the discrepancy in the accessible micro/mesoporosity between Ar and deuterated p-xylene that found for the two different carbon precursors, pitch and resin, which can be regarded as representative carbon precursors in general. These differences essentially indicate that physisorption using probe gases such as Ar or N2 can provide misleading parameters if to be used to appraise the accessibility of the nanoscale pore space.

Impact of formation and dissociation conditions on stiffness of a hydrate-bearing sand

2018 ◽  
Vol 55 (7) ◽  
pp. 988-998 ◽  
Author(s):  
Amit Sultaniya ◽  
Jeffrey A. Priest ◽  
C.R.I. Clayton
Keyword(s):  
Effective Stress ◽  
Pore Space ◽  
Hydrate Formation ◽  
Thermal Stimulation ◽  
Resonant Column ◽  
Rapid Reduction ◽  
Gas Recovery ◽  
Future Production ◽  
Hydrate Saturation ◽  
The Impact

Methane gas recovery from gas hydrate–bearing sands requires dissociation of the hydrate. Understanding changes in the stiffness of the sand is essential if future production scenarios are to be modelled realistically. This paper reports the results of resonant column tests conducted to measure changes in shear and flexural Young’s modulus (stiffness) of sand specimens during the formation and dissociation of hydrate within the pore space. Factors such as hydrate saturation, effective stress, and dissociation method (thermal stimulation and depressurization) were evaluated. Results show a nonlinear relationship between stiffness and hydrate volume, with hydrate formation and dissociation giving markedly different changes in stiffness. Stiffness increases more slowly during the initial stages of hydrate formation, compared to later stages, with the eventual stiffness being independent of the effective stress applied at the start of formation. In contrast, the onset of dissociation leads to a rapid reduction in stiffness, with thermal stimulation giving a greater reduction compared to depressurization for similar changes in hydrate volume. These results highlight the impact of hydrate morphology on changes in stiffness during the hydrate formation process or its dissociation. We present and discuss a conceptual model to explain the differences observed.

scholarly journals Halo uncertainties in electron recoil events at direct detection experiments

2021 ◽  
Vol 81 (11) ◽  
Author(s):  
Tarak Nath Maity ◽  
Tirtha Sankar Ray ◽  
Sambo Sarkar
Keyword(s):  
Dark Matter ◽  
Phase Space ◽  
Direct Detection ◽  
Space Distribution ◽  
Semiconductor Detectors ◽  
Detection Rates ◽  
Phase Space Distribution ◽  
Electron Recoil ◽  
Highly Correlated ◽  
The Impact

AbstractThe dark matter direct detection rates are highly correlated with the phase space distribution of dark matter particles in our galactic neighbourhood. In this paper we make a systematic study of the impact of astrophysical uncertainties on electron recoil events at the direct detection experiments with Xenon and semiconductor detectors. We find that within the standard halo model there can be up to $$ \sim 50\%$$ ∼ 50 % deviation from the fiducial choice in the exclusion bounds from these observational uncertainties. For non-standard halo models we report a similar deviation from the fiducial standard halo model when fitted with recent cosmological N-body simulations while even larger deviations are obtained in case of the observational uncertainties.

N fertilization effects on N2O fluxes from oil palm plantation on tropical peatland

2021 ◽  
Author(s):  
Auldry Chaddy ◽  
Lulie Melling ◽  
Kiwamu Ishikura ◽  
Ryusuke Hatano
Keyword(s):  
Oil Palm ◽  
Elaeis Guineensis ◽  
Pore Space ◽  
Anthropogenic Activities ◽  
N Uptake ◽  
N Fertilization ◽  
Soil N ◽  
Tropical Peatland ◽  
Oil Palm Plantation ◽  
The Impact

<p>Anthropogenic activities, and in particular the use of synthetic nitrogen (N) fertilizer, have a significant influence on soil nitrous oxide (N<sub>2</sub>O) emission from oil palm plantation on tropical peatland. Finding a suitable N rate for optimum N uptake efficiency and yield with low environmental impact and production cost is crucial for the economic growth of Malaysia’s oil palm sector. However, studies on the impact of N fertilizers on N<sub>2</sub>O emissions from tropical peatland are limited. Thus, long-term monitoring was conducted to investigate the effects of N fertilization on soil N<sub>2</sub>O emissions. This study was conducted in an oil palm (<em>Elaeis guineensis Jacq</em>.) plantation located in a tropical peatland in Sarawak, Malaysia. Monthly soil N<sub>2</sub>O fluxes were measured using the closed-chamber method in a control (T1, without N fertilization), and under three different N treatments: low N (T2, 31.1 kg N ha<sup>−1</sup>), moderate N (recommended rate) (T3, 62.2 kg N ha<sup>−1</sup>), and high N (T4, 124.3 kg N ha<sup>−1</sup>), from January 2010 to December 2013 and from January 2016 to December 2017. The only N fertiliser rate to significantly increase (p<0.05) annual cumulative N<sub>2</sub>O emissions was 124.3 kg N ha<sup>-1</sup> (T4). Increased in water-filled pore space (WFPS) (>70%) with a decrease in both N<sub>2</sub>O flux and nitrate (NO<sub>3</sub><sup>−</sup>) implies that complete denitrification has taken place. Increased in NO<sub>3</sub><sup>-</sup> uptake by oil palm with an increase in WFPS decreased NO<sub>3</sub><sup>-</sup> concentration in soil, resulting in the reduction of N<sub>2</sub>O emission. This study highlights the importance of WFPS on denitrification and <span>N uptake </span><span>by oil palm in tropical peatland. This needs to be taken into account for the accurate assessment of N dynamics in oil palm plantations on tropical peatland in order to enhance N fertilization management strategies and counteract anthropogenic activities that produce greenhouse gases.</span></p><p>Keywords: WFPS, oil palm yield, NO<sub>3</sub><sup>-</sup>, N uptake</p>

scholarly journals The Controls of Pore-Throat Structure on Fluid Performance in Tight Clastic Rock Reservoir: A Case from the Upper Triassic of Chang 7 Member, Ordos Basin, China

Geofluids ◽  
2018 ◽  
Vol 2018 ◽  
pp. 1-17 ◽  
Author(s):  
Yunlong Zhang ◽  
Zhidong Bao ◽  
Fei Yang ◽  
Shuwei Mao ◽  
Jian Song ◽  
...  
Keyword(s):  
Water Saturation ◽  
Pore Space ◽  
Ordos Basin ◽  
Significant Proportion ◽  
Pore Throat ◽  
Tight Sandstone ◽  
Clastic Rock ◽  
Control Factors ◽  
Significant Difference ◽  
The Impact

The characteristics of porosity and permeability in tight clastic rock reservoir have significant difference from those in conventional reservoir. The increased exploitation of tight gas and oil requests further understanding of fluid performance in the nanoscale pore-throat network of the tight reservoir. Typical tight sandstone and siltstone samples from Ordos Basin were investigated, and rate-controlled mercury injection capillary pressure (RMICP) and nuclear magnetic resonance (NMR) were employed in this paper, combined with helium porosity and air permeability data, to analyze the impact of pore-throat structure on the storage and seepage capacity of these tight oil reservoirs, revealing the control factors of economic petroleum production. The researches indicate that, in the tight clastic rock reservoir, largest throat is the key control on the permeability and potentially dominates the movable water saturation in the reservoir. The storage capacity of the reservoir consists of effective throat and pore space. Although it has a relatively steady and significant proportion that resulted from the throats, its variation is still dominated by the effective pores. A combination parameter (ε) that was established to be as an integrated characteristic of pore-throat structure shows effectively prediction of physical capability for hydrocarbon resource of the tight clastic rock reservoir.

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