共查询到20条相似文献,搜索用时 31 毫秒
1.
Chenghang Zheng Xintao Liu Xi Xu Pei Yan Qianyun Chang Yi Wang Xiang Gao 《Proceedings of the Combustion Institute》2019,37(3):2959-2965
A high-temperature electrostatic precipitator (ESP) presents a good solution for hot gas cleaning, which can remove fly ash from pyrolysis gas at temperatures higher than the tar dew point. In this paper, the characteristics of negative DC corona discharge in air and simulated coal pyrolysis gas were studied. The removal of coal pyrolysis furnace fly ash (ash A) was investigated and compared with that of coal-fired power plant fly ash (ash B) in ESP with a temperature ranging from 300?K to 900?K. The current density of simulated gas was higher than that of air under the same discharge voltage and at different temperatures. The simulated gas also had a higher spark voltage and a lower onset voltage compared with air. The fractional collection efficiency of ash A was lower for particles with diameters of larger than 0.1?µm at high temperature, compared with ash B. A lower collection efficiency in simulated gas was obtained for particles with diameters of less than 0.1?µm compared with air. The collection efficiency of submicron particles in simulated gas was usually higher than it in air, especially for particles with diameters of less than 0.04?µm. In simulated gas, the overall collection efficiency of ash A was obviously lower than that of ash B, especially at high temperature. From 300?K to 700?K, the collection efficiencies of both ash samples were as high as above 93%, but the collection efficiency of ash A in simulated gas decreased to 78.7% at 900?K. 相似文献
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M. Groß F. Spiegelmann 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1998,4(2):219-224
We present a pseudopotential method to study the absorption spectroscopy of NO in an argon matrix modeled by a large albeit
finite cluster. The excited states of NO are described with the virtual orbitals of a NO+ Hartree-Fock calculation plus a core-polarization operator to account for the electron-NO+ correlation. The argon atoms of the matrix are replaced by pseudopotentials for the repulsive contributions and core-polarization
operators to account for matrix polarization and correlation with the excited electron. The model is shown to account for
the matrix-induced transition shifts and also for the cut-off of the Rydberg series for n >3 reported in absorption experiments from the ground state.
Received: 6 March 1998 / Revised: 1st June 1998 / Accepted: 16 June 1998 相似文献
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We developed and tested a system that combines a vacuum ultraviolet single photon ionization time-of-flight mass spectrometer (VUV-SPI-TOFMS) with a Fourier transform-infrared (FT-IR) spectrometer and used it for the simultaneous detection of the various compounds generated during the pyrolysis of coal. We characterized the performance of the system, including its limits of detection and time resolution. We also determined the various compounds that could be detected using the system. The instrument exhibited a laboratory-determined detection limit that was in the parts per billion volume (ppbv) range and a detection time of 10 s for most of the aromatic compounds generated during the pyrolysis process. In addition, using this system, it was possible to determine the correlation between the pyrolysis temperature and the various compounds generated from different types of coals during the pyrolysis process. 相似文献
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Gülen Ferah Kemal Colakoglu Yasemin Oztekin Ciftci Soner Ozgen Sefa Kazanc 《Central European Journal of Physics》2007,5(2):207-220
In this study, molecular dynamics simulations are performed by using a modified form of Morse potential function in the framework
of the Embedded Atom Method (EAM). Temperature-and pressure-dependent behaviours of bulk modulus, second-order elastic constants
(SOEC), and the linear-thermal expansion coefficient is calculated and compared with the available experimental data. The
melting temperature is estimated from 3 different plots. The obtained results are in agreement with the available experimental
findings for iridium.
相似文献
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Molecular dynamics calculations were carried out in order to investigate the hydration structure of uranyl in aqueous solution. The CF1 model of flexible water molecules is used. This model allows one to investigate a hydrolysis reaction for water molecules in the first uranyl hydration shell. Charge redistribution effects on hydrolysis products are also taken into account. We found five ligands in uranyl hydration shell, which is of bipyramidal pentacoordinated structure. The charge redistribution effects resulted in ligands of four water molecules and one hydroxyl, which was found closer to uranium than the other ligands. 相似文献
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《Current Applied Physics》2014,14(9):1216-1227
With the rapid progression of bionanorobotics, manipulation of nano-scale biosamples is becoming increasingly attractive for different biological purposes. Nevertheless, the interaction between a robotic probe and a biological sample is poorly understood and the conditions for appropriate handling is not well-known. Here, we use the molecular dynamics (MD) simulation method to investigate the manipulation process when a nanoprobe tries to move a biosample on a substrate. For this purpose, we have used Ubiquitin (UBQ) as the biomolecule, a single-walled carbon nanotube (SWCNT) as the manipulation probe, and a double-layered graphene sheets as the substrate. A series of simulations were conducted to study the effects of different conditions on the success of the manipulation process. These conditions include the tip diameter, the vertical gap between the tip and substrate, and the initial orientation of the protein. Also we have studied two strategies for the manipulation of the protein by a nano-scale probe that we have named pushing and pulling. Interaction force between carbon nanotube (CNT) tips and the biomolecule, the root-mean-square deviation (RMSD), and the radius of gyration of the protein are monitored for different conditions. We found that larger tip diameters, smaller gaps between tip and substrate, and a pulling strategy increase the chance of a successful manipulation. 相似文献
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Dielectrophoresis of nanocolloids: A molecular dynamics study 总被引:1,自引:0,他引:1
Salonen E Terama E Vattulainen I Karttunen M 《The European physical journal. E, Soft matter》2005,18(2):133-142
Dielectrophoresis (DEP), the motion of polarizable particles in non-uniform electric fields, has become an important tool
for the transport, separation, and characterization of microparticles in biomedical and nanoelectronics research. In this
article we present, to our knowledge, the first molecular dynamics simulations of DEP of nanometer-sized colloidal particles.
We introduce a simplified model for a polarizable nanoparticle, consisting of a large charged macroion and oppositely charged
microions, in an explicit solvent. The model is then used to study DEP motion of the particle at different combinations of
temperature and electric field strength. In accord with linear response theory, the particle drift velocities are shown to
be proportional to the DEP force. Analysis of the colloid DEP mobility shows a clear time dependence, demonstrating the variation
of friction under non-equilibrium. The time dependence of the mobility further results in an apparent weak variation of the
DEP displacements with temperature. 相似文献
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An extensive body of experimental data is presently available on Senftleben-Beenakker and related effects for a variety of polyatomic gases. This data presents the theoretician with an opportunity to test approximations in kinetic theory, collision dynamics, and anisotropic intermolecular potential functions. Although both formal theoretical developments and quantum mechanical computations have been areas of considerable activity, it has only been feasible to apply the usual numerical quantum mechanical techniques to hydrogen isotopic molecules. In this paper, we provide theoretical results for affective cross sections for one of the heavier collisions systems that has been thoroughly studied experimentally. We have developed an approach in which classical ansatz equations for the various effective cross sections are derived and evaluated via classical trajectories. As in a previous study of depolarized Rayleigh line broadening, where the classical ansatz expression was shown to be identical to a semiclassically derived expression, the system N2?N2 has been chosen for the present investigation. The relative importance of the “second molecule” contributions to the various effective cross sections as well as the role of quadrupole-quadrupole forces have been explored. In general we find close agreement between the calculated results and experiment for effective cross sections involving only molecular velocity terms and poorer agreement for those which also include angular momentum terms. The results show that the present approach provides considerable insight into the microscopic collisional processes and intermolecular forces which give rise to the observable cross sections, as well as providing an opportunity to compare computational results with experiment. 相似文献
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Borophene, an atomically thin, corrugated, crystalline two-dimensional boron sheet, has been recently synthesized. Here we investigate mechanical properties and lattice thermal conductivity of borophene using reactive molecular dynamics simulations. We performed uniaxial tensile strain simulations at room temperature along in-plane directions, and found 2D elastic moduli of 188 N m−1 and 403 N m−1 along zigzag and armchair directions, respectively. This anisotropy is attributed to the buckling of the borophene structure along the zigzag direction. We also performed non-equilibrium molecular dynamics to calculate the lattice thermal conductivity. Considering its size-dependence, we predict room-temperature lattice thermal conductivities of 75.9 ± 5.0 W m−1 K−1 and 147 ± 7.3 W m−1 K−1, respectively, and estimate effective phonon mean free paths of 16.7 ± 1.7 nm and 21.4 ± 1.0 nm for the zigzag and armchair directions. In this case, the anisotropy is attributed to differences in the density of states of low-frequency phonons, with lower group velocities and possibly shorten phonon lifetimes along the zigzag direction. We also observe that when borophene is strained along the armchair direction there is a significant increase in thermal conductivity along that direction. Meanwhile, when the sample is strained along the zigzag direction there is a much smaller increase in thermal conductivity along that direction. For a strain of 8% along the armchair direction the thermal conductivity increases by a factor of 3.5 (250%), whereas for the same amount of strain along the zigzag direction the increase is only by a factor of 1.2 (20%). Our predictions are in agreement with recent first principles results, at a fraction of the computational cost. The simulations shall serve as a guide for experiments concerning mechanical and thermal properties of borophene and related 2D materials. 相似文献
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Rongbin Li 《Solid State Communications》2005,135(3):155-157
Based upon molecular dynamics simulation via the Tersoff many-body potential, we proposed the co-doping method for fabricating n-type diamond. We calculated the optimal co-doping configurations of n-type (nitrogen) and p-type (boron) dopants, the stable structure of a boron atom in diamond is associated with four nitrogen atoms placed at the nearest neighbour positions, the total energy of the system with the stable structure is 136 MeV lower than that of the system with the nitrogen atoms placed in others positions. The results indicated that the co-dopants of nitrogen and boron were the perfect candidates to make n-type diamond, and additional boron would increase the solubility limit of nitrogen in diamond, reduce the lattice-relaxation energy of crystal and improve its doping efficiency in diamond. 相似文献
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We simulate the twist of carbon nanotubes using atomic molecular dynamic simulations. The ultimate twist angle per unit length and the deformation energy are calculated for nanotubes of different geometries. It is found that the thick tube is harder to be twisted while the thin tube exhibits higher ultimate twisting ratio. For multi-walled nanotubes, the zigzag tube is found to be able to stand more deformation than the armchair one. We observed the surface transformation during twisting. Formation of structural defects is observed prior to fracture. 相似文献
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Molecular dynamics (MD) simulations of sputtering process with fluorine cluster impact onto silicon targets were performed. By iterating collisional simulations on a same target, accumulation of incident atoms and evolution of surface morphology were examined as well as emission process of precursors. When (F2)300 clusters were sequentially irradiated on Si(1 0 0) target at 6 keV of total incident energy, column-like surface structure covered with F atoms was formed. As the number of incident clusters increased, sputtering yield of Si atoms also increased because the target surface was well fluoridised to provide SiFx precursors. Size distribution of emitted particles showed that SiF2 was the major sputtered particle, but various types of silicon-fluoride compounds such like Si2Fx, Si3Fx and very large molecules consists of 100 atoms were also observed. This size distribution and kinetic energy distribution of desorbed materials were studied, which showed that the sputtering mechanism with reactive cluster ions is similar to that under thermal equilibrium condition at high-temperature. 相似文献
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Hirshfeld D Rapaport DC 《Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics》2000,61(1):R21-R24
Molecular dynamics methods have been used in a quantitative study of the growth and decay of Taylor vortices in a fluid confined between concentric cylinders when the rotation of the inner cylinder is instantaneously started or stopped. Analysis of the temporal evolution of the vortex flow fields shows that the behavior of this microscopic system agrees with experiment. In order to make the analysis entirely self-contained, torque measurements have been used to determine the effective viscosity of the fluid. 相似文献