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排序方式: 共有249条查询结果,搜索用时 15 毫秒
41.
42.
Afsaneh Mehran 《manuscripta mathematica》2007,123(2):205-235
Besides its construction as a quotient of an abelian surface, a Kummer surface can be obtained as the quotient of a K3 surface
by a -action. In this paper, we classify all such K3 surfaces. Our classification is expressed in terms of period lattices and
extends Morrison’s criterion of K3 surfaces with a Shioda–Inose structure. Moreover, we list all the K3 surfaces associated
to a general Kummer surface and provide very geometrical examples of this phenomenon. 相似文献
43.
Javanbakht M Badiei A Ganjali MR Norouzi P Hasheminasab A Abdouss M 《Analytica chimica acta》2007,601(2):172-182
A new functionalized nanoporous silica gel with dipyridyl group (DPNSG) was synthesized. Then, the potentiometric response of the copper(II) ion was investigated at a carbon paste electrode chemically modified with this newly designed functionalized nanoporous silica gel. The electrodes with DPNSG proportions of 15.0% (w/w) demonstrated very stable potentials. Calibration plots with Nernstian slopes for Cu2+ were observed, 28.4 (±1.0) mV decade−1, over a wide linear concentration range (1.0 × 10−7 to 1.0 × 10−2 M). The electrode exhibited a detection limit of 8.0 × 10−8 M. Moreover, the selectivity coefficients measured by the match potential method in acetate buffer, pH 5.5, were investigated. The electrode presented a response time of ∼50 s, high performance, high sensitivity in a wide range of cation activities and good long-term stability (more than 9 months). The method was satisfactory and was used to determine the copper ion concentration in waste waters, contaminated by this metal. 相似文献
44.
A new diffusion-based solid-phase microextraction (SPME) time-weighted average (TWA) field water sampling device was developed and investigated by field trial. The sampler is constructed with copper tube and caps and a commercial SPME fiber assembly. The device possesses all advantages of SPME; it is solvent-free, reusable, combines sampling, isolation and enrichment into one step, and the fiber can be directly injected into a gas chromatograph for analysis with a commercial SPME fiber holder, without further treatment. Field trials in Laurel Creek (Waterloo, Ont., Canada) and Hamilton Harbour (Hamilton, Ont., Canada) illustrated that the device is durable, easy to deploy, and the mass uptake of the device is independent of the face velocity. The device provides good precision [relative standard deviations (RSDs) are less than 20%] and the data obtained with this device are quite comparable to those obtained with the spot sampling method, which demonstrates that the newly developed SPME water sampling device is suitable for long-term monitoring of organic pollutants in water. 相似文献
45.
The nonlinear aspects of nonplanar dust acoustic (DA) solitary waves are investigated in an unmagnetized complex plasma comprising of cold dust grains, kappa-distributed ions as well as electrons. The nonplanar DA solitons are studied based on the reductive perturbation technique. It is shown that the evolution of DA solitons is governed by a spherical Kadomtsev-Petviashvili (sKP) equation and then the impact of suprathermality on the spatial structure as well as the nature of DA soliton is studied. It seems that the properties of DA solitons in nonplanar geometry are quite different from that of the planar solitons. 相似文献
46.
Mehran?SohrabiEmail author Nor?Idah?Kechut Masoud?Riazi Mahmoud?Jamiolahmady Shaun?Ireland Graeme?Robertson 《Transport in Porous Media》2012,91(1):101-121
Carbonated water injection (CWI) is a CO2-augmented water injection strategy that leads to increased oil recovery with added advantage of safe storage of CO2 in oil reservoirs. In CWI, CO2 is used efficiently (compared to conventional CO2 injection) and hence it is particularly attractive for reservoirs with limited access to large quantities of CO2, e.g. offshore reservoirs or reservoirs far from large sources of CO2. We present the results of a series of CWI coreflood experiments using water-wet and mixed-wet Clashach sandstone cores and
a reservoir core with light oil (n-decane), refined viscous oil and a stock-tank crude oil. The experiments were carried out to assess the performance of CWI
and to quantify the level of additional oil recovery and CO2 storage under various experimental conditions. We show that the ultimate oil recovery by CWI is higher than the conventional
water flooding in both secondary and tertiary recovery methods. Oil swelling as a result of CO2 diffusion into the oil and the subsequent oil viscosity reduction and coalescence of the isolated oil ganglia are amongst
the main mechanisms of oil recovery by CWI that were observed through the visualisation experiments in high-pressure glass
micromodels. There was also evidence of a change in the rock wettability that could also influence the oil recovery. The coreflood
test results also reveal that the CWI performance is influenced by oil viscosity, core wettability and the brine salinity.
Higher oil recovery was obtained with the mixed-wet core than the water-wet core, with light oil than with the viscous oil
and low salinity carbonated brine than high-salinity carbonated brine. At the end of the flooding period, an encouraging amount
of the injected CO2 was stored in the brine and the remaining oil in the form of stable dissolved CO2. The experimental results clearly demonstrate the potential of CWI for improving oil recovery as compared with the conventional
water flooding (secondary recovery) or as a water-based EOR (enhanced oil recovery) method for watered out reservoirs. 相似文献
47.
Mehran Minbashi Mir Kazem Omrani Nafiseh Memarian Dae-Hwan Kim 《Current Applied Physics》2017,17(10):1238-1243
The simulation of CZTSSe solar cells is presented in this paper. The simulation results are in reasonable agreement with the experimental data, indicating the reliability of simulation results. New structure is proposed to increase the functionality of the cell. Improved functional performances are achieved by inserting a P-Silicon (P-Si) layer as back surface field. Simulation results suggest that by inserting this P-Si layer, efficiency of the CZTSSe solar cell increases from 12.6% to 16.59%, which is a significant improvement. For the champion cell JSC = 36.27 mA/cm2, VOC = 0.625 V and FF = 73.11% has been achieved. 相似文献
48.
Ramin Rabani Ahmadreza K. Faghih Mehrdad Rabani Mehran Rabani 《Heat and Mass Transfer》2014,50(11):1609-1625
In this study, passive cooling of a room using a solar chimney and water spraying system in the room inlet vents is simulated numerically in Yazd, Iran (a hot and arid city with very high solar radiation). The performance of this system has been investigated for the warmest day of the year (5 August) which depends on the variation of some parameters such as water flow rate, solar heat flux, and inlet air temperature. In order to get the best performance of the system for maximum air change and also absorb the highest solar heat flux by the absorber in the warmest time of the day, different directions (West, East, North and South) have been studied and the West direction has been selected as the best direction. The minimum amount of water used in spraying system to set the inside air averaged relative humidity <65 % is obtained using trial and error method. The simulation results show that this proposed system decreases the averaged air temperature in the middle of the room by 9–14 °C and increases the room relative humidity about 28–45 %. 相似文献
49.
Farhangi MM Graham PJ Choudhury NR Dolatabadi A 《Langmuir : the ACS journal of surfaces and colloids》2012,28(2):1290-1303
Coalescence of a falling droplet with a stationary sessile droplet on a superhydrophobic surface is investigated by a combined experimental and numerical study. In the experiments, the droplet diameter, the impact velocity, and the distance between the impacting droplets were controlled. The evolution of surface shape during the coalescence of two droplets on the superhydrophobic surface is captured using high speed imaging and compared with numerical results. A two-phase volume of fluid (VOF) method is used to determine the dynamics of droplet coalescence, shape evaluation, and contact line movement. The spread length of two coalesced droplets along their original center is also predicted by the model and compared well with the experimental results. The effect of different parameters such as impact velocity, center to center distance, and droplet size on contact time and restitution coefficient are studied and compared to the experimental results. Finally, the wetting and the self-cleaning properties of superhydrophobic surfaces have been investigated. It has been found that impinging water drops with very small amount of kinetic impact energy were able to thoroughly clean these surfaces. 相似文献
50.
The flow of non-Newtonian fluids through two-dimensional porous media is analyzed at the pore scale using the smoothed particle
hydrodynamics (SPH) method. A fully explicit projection method is used to simulate incompressible flow. This study focuses
on a shear-thinning power-law model (n < 1), though the method is sufficiently general to include other stress-shear rate relationships. The capabilities of the
proposed method are demonstrated by analyzing a Poiseuille problem at low Reynolds numbers. Two test cases are also solved
to evaluate validity of Darcy’s law for power-law fluids and to investigate the effect of anisotropy at the pore scale. Results
show that the proposed algorithm can accurately simulate non-Newtonian fluid flows in porous media. 相似文献