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11.
Matrix–fracture transfer functions are the backbone of any dual-porosity or dual-permeability formulation. The chief feature
within them is the accurate definition of shape factors. To date, there is no completely accepted formulation of a matrix–fracture
transfer function. Many formulations of shape factors for instantly-filled fractures with uniform pressure distribution have
been presented and used; however, they differ by up to five times in magnitude. Based on a recently presented transfer function,
time-dependent shape factors for water imbibing from fracture to matrix under pressure driven flow are proposed. Also new
matrix–fracture transfer pressure-based shape factors for instantly-filled fractures with non-uniform pressure distribution
are presented in this article. These are the boundary conditions for a case for porous media with clusters of parallel and
disconnected fractures, for instance. These new pressure-based shape factors were obtained by solving the pressure diffusivity
equation for a single phase using non-uniform boundary conditions. This leads to time-dependent shape factors because of the
transient part of the solution for pressure. However, approximating the solution with an exponential function, one obtains
constant shape factors that can be easily implemented in current dual-porosity reservoir simulators. The approximate shape
factors provide good results for systems where the transient behavior of pressure is short (a case commonly encountered in
fractured reservoirs). 相似文献
12.
Muthiah Manoharan Akin Akinc Rajendra K. Pandey June Qin Philipp Hadwiger Matthias John Kathy Mills Klaus Charisse Martin A. Maier Lubomir Nechev Emily M. Greene Pradeep S. Pallan Eriks Rozners Kallanthottathil G. Rajeev Martin Egli 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2011,123(10):2332-2336
13.
Classical vehicle routing problems typically do not consider the impact of delivery price on the demand for delivery services. Existing models seek the minimum sum of tour lengths in order to serve the demands of a given set of customers. This paper proposes approximation models to estimate the impacts of price on delivery services when demand for delivery service is price dependent. Such models can serve as useful tools in the planning phase for delivery service providers and can assist in understanding the economics of delivery services. These models seek to maximize profit from delivery service, where price determines demand for deliveries as well as the total revenue generated by satisfying demand. We consider a variant of the model in which each customer’s delivery volume is price sensitive, as well as the case in which customer delivery volumes are fixed, but the total number of customers who select the delivery service provider is price sensitive. A third model variant allows the delivery service provider to select a subset of delivery requests at the offered price in order to maximize profit. 相似文献
14.
15.
In a radial flow pump operating in off-design conditions, regions of stall can exist on the rotating impeller blade and on the downstream diffuser blade, vane or tongue. Interaction of these stall zones can generate complex patterns of vorticity concentrations. In turn, these vorticity concentrations are related to sources of unsteady stagnation enthalpy. The form of these patterns is strongly dependent on the instantaneous location of the impeller trailing-edge relative to the leading-edge of the vane.Comparison of instantaneous with ensemble-averaged images shows that the flow structure in the gap region between the impeller and the vane is highly repetitive. Away from this region, in particular in the separated shear layer from the vane, the nonrepetitive nature of the vorticity field is manifested in substantial reduction of peak levels of vorticity in the ensemble-averaged image, relative to the instantaneous image.The three-dimensional flow structure resulting from these separation zone interactions was characterized via end views of the flow patterns. Particularly pronounced concentrations of vorticity can occur in this plane. They tend to be located in the shear layer at the outer edge of the large-scale separation zone. These vorticity concentrations are, however, highly non-stationary for successive passages of the impeller blade. Ensemble-averaging reveals that they persist primarily on the endwalls of the diffuser.The authors are grateful to the Office of Naval Research for support of this research program 相似文献
16.
In this study, electrochemical degradation of microcrystalline cellulose (MCC) under hot-compressed water was investigated via application of constant voltage on reaction medium. Constant voltage ranges from 2.5 to 8.0 V was applied between anode (Titanium) and cathode (reactor wall). As an electrolyte and proton source 5–25 mM of H2SO4 was used. Reactions were carried out in a specially designed batch reactor (450 mL) made of T316 for 240 min at temperature of 200 °C.MCC decomposition products such as glucose, fructose, furfural, 5-HMF and levulinic acid were detected and quantified by High Performance Liquid Chromatography (HPLC). In the absence of electrolyte, applied voltage (2.5 and 4.0 V) decreased the total organic carbon (TOC) yield, in contrast at 8.0 V, TOC yield increased to 13%. Application of 8.0 V in hydrothermal conditions alter MCC decomposition pathway selectively to furfural (15%). Addition of electrolyte (5 mM, H2SO4) and application of 2.5 V potential increased TOC (54%) and changed the decomposition pathway in favor of 5-HMF (30%) and levulinic acid (21%). The structural changes in solid residues of electrochemically reacted MCC was analyzed by Fourier Transform Infrared Spectroscopy (FTIR) and found that MCC particles functionalized by carboxylic acid and sulfonated groups by the application of constant voltage to reaction medium. In the presence of electrolyte, under certain voltage (2.5 V), functionalization of solid particles became more obvious in FTIR spectrum results. Therefore, change in the selectivity values of degradation products were conducted with the functionalization of MCC particles due to applied voltage under sub-critical conditions. 相似文献
17.
F. A. Akin 《Molecular physics》2013,111(24):3556-3566
ABSTRACTThe structures, ionisation energies (IE), and electron affinities (EA) of 1,3,5-trinitro-1,3,5-triazacyclohexane (RDX) isomers upon loss and gain of an electron were calculated using density functional theory (DFT) methods. The adiabatic electron affinities (EAad) range from 1 to 2 eV. The vertical detachment energies are between 1.3 and 4.0 eV. The adiabatic ionisation energies (IEad) are in the 9.9–10.2 eV range. The vertical ionisation energies are in the 10.4–10.9 eV range. It is shown that NO2?/NO2 loss would be common in anions and cations, respectively. Isomerisation and N—N bond dissociation accompany cation and anion formation, respectively. The suggested mass spectral fragmentation products for the cations along the S0 surface are 84, 130, and 176 amu, in agreement with earlier mass spectrometry studies. 相似文献
18.
Tuning the shape anisotropy of silver nanoparticles using time-delayed laser pulse pair irradiations
A. Akin Unal A. Stalmashonak H. Graener G. Seifert 《Applied physics. B, Lasers and optics》2010,101(4):841-847
Glass-embedded spherical silver nanoparticles were irradiated by pairs of delayed femtosecond laser pulses. The influence of intensity, relative polarization (parallel or orthogonal) and time delay between the pulses was investigated. We found a delay-dependent reversal of the orientation of prolate nanoparticles produced in the low-intensity regime: at very short time delays up to 10 ps between pulse pairs the polarization direction of the second-hitting pulse defines the particles’ symmetry axes; in an intermediate regime between 10 and 20 ps no optical dichroism is found at all; at more than 20 ps delay between the pulses, finally, the transformed nanoparticles are oriented along the polarization direction of the first-hitting pulse. Also, in the quite different situation of the high-intensity regime using parallel-polarized pulse pairs, where normally oblate particles are created, isotropic spectral changes (i.e., no dichroism) after irradiation were observed at delay times around 20 ps. The possible physical background of this apparently very special inter-pulse delay of around 20 ps is discussed. 相似文献
19.
The steady-state fluorescence (SSF) technique was introduced for studying swelling of disc-shaped polyacrylamide (PAAm) gels containing various amount of κ?carrageenan (κC). They were prepared by free-radical cross-linking copolymerization. N,N′-methylenebisacrylamide (BIS) and ammonium persulfate (APS) were added as a cross-linker and an initiator, respectively. Composite gels were prepared at 80°C with pyranine as a fluorescence probe. After drying of these gels, swelling kinetics were performed in water at 60°C by real-time monitoring of the pyranine fluorescence intensity, I, which decreased as swelling proceeded. The Li–Tanaka equation was used to determine the swelling time constants, τ 1, and cooperative diffusion coefficients, D 0, from fluorescence intensity, weight, and volume variations of the gels during the swelling processes in all cases. It was observed that τ 1 decreased and D 0 increased as the κC concentrations in the composites were increased indicating that high κC gels swell faster than low κC gels. 相似文献
20.
We study a phase transition problem for the q-state p-adic Potts model on the Cayley tree of order three. We find certain conditions for the existence of p-adic Gibbs measures and then establish the existence of a phase transition. 相似文献