1,721,092 research outputs found
Estimations of the upper and lower depth limits for kerogen to generate oil/gas worldwide: A hypothesis
No full textThis study focuses on the upper and lower depth limits for kerogen to generate oil/gas worldwide. For the first time, the upper and lower depth limits of the conversion process from kerogen to oil/gas are given by the equations with clear physical significance. The method for obtaining the parameters in the equations is also proposed. The results show that the upper limit of hydrocarbon generation of kerogen mainly depends on the ratio of the minimum dissociation energy and initial molar mass of hydrocarbon generation. The smaller the ratio is, the shallower the upper limit of hydrocarbon generation of kerogen is. The upper depth limit of hydrocarbon generation ranges from 688 m to 4925 m, with an average of 1944 m. The lower limit of hydrocarbon generation mainly depends on the ratio of the dissociation energy and molar mass at the end of hydrocarbon generation. The lower depth limit of hydrocarbon generation is proportional to the above ratio. The lower limit of hydrocarbon generation of kerogen ranges from 2539 m to 16 337 m, with an average of 6926 m. This study not only solves a major controversial issue which is the minimum and maximum depth of drilling required to capture oil/gas but also helps select the location of carbon storage. It will be conducive to the effective utilization of fossil energy and the early realization of global carbon neutralization. (c) 2023 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.</p
The Constructions and Pyrolysis of 3D Kerogen Macromolecular Models: Experiments and Simulations
No full textKerogens are extracted from deep shales to study pyrolysis of deep shale samples. The 2D molecular models of kerogens are obtained by a series of physical and chemical experiments by which the macromolecular models of kerogens are constructed. Then, the reasonable 3D macromolecular models are established by molecular mechanics and global energy minimization. The effects of temperature and heating rate on the chemical kinetics of kerogen pyrolysis are studied using reactive force field (ReaxFF). The hybrid molecular dynamics/force-biased Monte Carlo (MD/fbMC) approach is used to simulate the pyrolytic process at the experimental temperature, which is lower than the conventional one. The gaseous products and residues obtained by the simulations agree with the experimental results, which means a reliable simulation method for pyrolysis at experimental temperature is provided. This study constructs the rational macromolecular models of kerogen by experiments, and proposes the mechanisms of typical reactions of kerogen pyrolysis, which may help in understanding the formation of shale oil and gas.</p
Tuning the structure of cerium-based metal-organic frameworks for efficient removal of arsenic species: The role of organic ligands
No full textThe ability of organic ligands to change the structure of metal-organic frameworks (MOFs) in nature and influence their adsorption efficiency for arsenic species is enormous. The current work was designed to investigate the adsorption performance of cerium-based MOFs with tunable structures through the use of organic ligands (Ce-MOF-66 and Ce-MOF-808) towards arsenic species from water. The structural features of Ce-MOF-66 and CeMOF-808 with varying crystallinity, morphology, particle size, and surface area are considerably altered by organic ligands tuning, resulting in clearly distinct arsenate (As (V)) and arsenite (As (III)) adsorption capabilities. The experimental results showed that the Langmuir adsorption capacities of As (V) by Ce-MOF-66 and CeMOF-808 reached 355.67 and 217.80 mg/g, respectively, while for As (III) were 5.52 and 402.10 mg/g for CeMOF-66 and Ce-MOF-808, respectively. Except for the impact of PO43- on As (V), co-existing ions had no significant influence on adsorption, illustrating the high selectivity. Furthermore, to understand the structure and adsorption mechanism, two adsorbents were characterized by powder X-ray diffraction, scanning electron microscopy, thermogravimetric analysis, specific surface area, Fourier transform infrared and X-ray photoelectron spectroscopy, in which identified that unsaturated sites and ligand exchange were the main adsorption mechanisms of As (V) and As (III). Overall, this research presents a novel approach for developing high-performance Ce-derived MOFs adsorbents to capture arsenic species
EXPERIMENTAL INVESTIGATION INTO THE DYNAMIC BEHAVIOR OF CIRCULAR RINGS WITH ARC-SHAPED SUPPORTS
No full textResults are presented of an experimental study on the dynamic behavior of metallic thin-walled circular rings with are-shaped supports subjected to a symmetrically concentrated impact load.http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:A1995QN47100009&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=8e1609b174ce4e31116a60747a720701Engineering, MultidisciplinaryEngineering, MechanicalSCI(E)EI2ARTICLE183-856
THE DYNAMIC VISCOPLASTIC BEHAVIOR OF THICK-WALLED SPHERICAL-SHELLS
No full textA theoretical analysis is presented for the dynamic viscoplastic response of thick-walled spherical shells subjected to internal pressure. The material is rigid-viscoplastic and incompressible; the viscoplastic constitutive equations due to Hohenemser and Prager are used. As a specific example, the quasi-static case is also studied.http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:A1994MT60300009&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=8e1609b174ce4e31116a60747a720701Engineering, MultidisciplinaryEngineering, MechanicalSCI(E)EI0ARTICLE2207-2105
DYNAMIC PLASTIC SHEAR FAILURE ANALYSIS FOR AN INFINITELY LARGE PLATE WITH A CENTERED CYLINDER UNDER IMPULSIVE LOADING
No full textThe transverse shear failure of a circular plate with an infinitely large outside radius, made from a rigid, perfectly plastic material, is considered. The plate has a rigid central cylindrical boss which is subjected to an initial impulsive velocity which causes a circular transverse shear hinge to develop at the interface between the boss and the plate. Two models are adopted in this paper. Rotatory inertia are disregarded in the first, the second retains the influence of rotatory inertia as well as bending moments. It is illustrated that whether a shear failure occurs or not at the interface, where the initial velocity has discontinuity, depends on the nondimensional initial kinetic energy, the material property and two ratios, one is the thickness of the plate to the radius of the boss, and the second is the density ratio of the boss to the plate. It is shown by the comparison between the two models that the influence of the rotatory inertia of the plate on the shear failure are not negligible.http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:A1994NN33200006&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=8e1609b174ce4e31116a60747a720701MechanicsSCI(E)EI8ARTICLE111585-15953
LARGE DYNAMIC PLASTIC DEFLECTION OF A SIMPLY SUPPORTED BEAM SUBJECTED TO RECTANGULAR PRESSURE PULSE
No full textThis paper concerns the dynamic behaviour of rigid, perfectly plastic simply supported beams with finite deflections by considering both bending moments and axial forces. In the case of rectangular pressure pulse loading, approximate rigid-plastic theoretical solutions are obtained for both medium load and high load; to this end a parabolic law between bending moment and axial force as yield condition is approximated by a circumscribing or an inscribing rectangle. The concept of Saturation Impulse is put forward for the dynamic response of rigid, perfectly plastic structures with finite deflections subjected to rectangular pressure pulse. The value of dimensionless saturation impulse for both simply supported and fully clamped beams are given.MechanicsSCI(E)7ARTICLE3223-2326
Similarity consideration of structural bifurcation buckling
No full textMany structural bifurcation buckling problems exhibit a scaling or power law property. Dimensional analysis is used to analyze the general scaling property. The concept of a new dimensionless number, the response number-Rn, suggested by the present author for the dynamic plastic response and failure of beams, plates and so on, subjected to large dynamic loading, is generalized in this paper to study the elastic, plastic, dynamic elastic as well as dynamic plastic buckling problems of columns, plates as well as shells. Structural bifurcation buckling can be considered when Rn(n) reaches a critical value
Photo-Fenton Degradation of Ciprofloxacin by Novel Graphene Quantum Dots/α-FeOOH Nanocomposites for the Production of Safe Drinking Water from Surface Water
No full textIn the current work, novel graphene quantum dots (GQDs)-doped goethite (α-FeOOH) nanocomposites (GQDs/α-FeOOH) were prepared by following a feasible hydrolysis method and applied for ciprofloxacin (CIP) removal. Results showed that the CIP degradation efficiency was significant (93.73%, 0.0566 min−1) in the GQDs/α-FeOOH + H2O2 + Vis system using much lower amounts of H2O2 (0.50 mM), which is 3.9 times the α-FeOOH + H2O2 + Vis system. It was found that •OH, O2•−, and 1O2 were mainly responsible for CIP degradation in the GQDs/α-FeOOH photo-Fenton system. GQDs/α-FeOOH demonstrated broad-spectrum UV–vis-IR responsiveness in the degradation of ciprofloxacin as a function of the doping of GQDs. Additionally, GQDs/α-FeOOH showed outstanding durability (recyclability up to 3 cycles with a lower iron leaking amount, 0.020 mg L−1), a broad range of application pH, and a pretty acceptable catalytic efficacy in a variety of surface water matrices. Overall, GQDs/α-FeOOH have been shown to be an effective photocatalyst for the remediation of emerging contaminants via the workable exploitation of solar energy
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