STOCHASTIC SIMULATION OF ELECTRON-HOLE RECOMBINATION IN TWO-DIMENSIONAL AND THREE-DIMENSIONAL INHOMOGENEOUS SEMICONDUCTORS. PART II. SIMULATION RESULTS

2017 ◽  
Keyword(s):  
Stochastic Simulation ◽  
Three Dimensional ◽  
Two Dimensional ◽  
Electron Hole ◽  
Simulation Results ◽  
Hole Recombination

Effects of hydrothermal temperature on the morphology and photoelectrocatalytic performance of TiO2-based nanomaterials photoelectrode

2015 ◽  
Vol 08 (04) ◽  
pp. 1550034 ◽  
Author(s):  
Dong Li ◽  
Xiujuan Yu ◽  
Xiuwen Cheng
Keyword(s):  
Three Dimensional ◽  
Photogenerated Electron ◽  
Comparative Investigation ◽  
Two Dimensional ◽  
X Ray Diffraction ◽  
Photoelectrochemical Performance ◽  
Electron Hole ◽  
Hydrothermal Temperature ◽  
Dimensional Network ◽  
Hole Recombination

TiO 2-based nanomaterials (BNMs) photoelectrode was successfully synthesized via a facile and controllable hydrothermal procedure. The as-prepared TiO 2-BNMs photoelectrode was characterized by field emission scanning electron microscopy (FE-SEM) and X-ray diffraction (XRD). The resulting TiO 2-BNMs samples assembled by different morphologies were obtained through changing hydrothermal temperature that were: (i) One-dimensional (relative to nanosheets) nanobelts at 140°C, (ii) two-dimensional nanosheets at 160–180°C and (iii) three-dimensional network nanowires at 200–220°C. Structural investigation of the obtained nanomaterials revealed that the content of anatase increased as increasing the apparent dimensionality of the materials. The photoelectrochemical performance of TiO 2-BNMs photoelectrode was elucidated by comparative investigation on the electron transport and electron–hole (e-/h+) recombination in TiO 2-BNMs sample with typically morphology. The photoelectrochemical performance of the TiO 2-BNMs sample was obviously dependent on the morphology. Compared to the nanobelts and the network nanowires structure, the two-dimensional nanosheets displayed the more effective photogenerated electron transfer and reduced electron–hole recombination rate. Moreover, two-dimensional nanosheets had significantly enhanced photoelectrocatalytic efficiency for degradation of methyl orange (MO).

Design of finite-time guidance law based on observer and head-pursuit theory

2021 ◽  
pp. 095441002098456
Author(s):  
Chenqi Zhu
Keyword(s):  
Finite Time ◽  
Three Dimensional ◽  
Hypersonic Vehicle ◽  
Two Dimensional ◽  
Dimensional Model ◽  
Reaching Law ◽  
Guidance Law ◽  
Fast Power ◽  
Simulation Results ◽  
Guidance Laws

In order to improve the guiding accuracy in intercepting the hypersonic vehicle, this article presents a finite-time guidance law based on the observer and head-pursuit theory. First, based on a two-dimensional model between the interceptor and target, this study applies the fast power reaching law to head-pursuit guidance law so that it can alleviate the chattering phenomenon and ensure the convergence speed. Second, target maneuvers are considered as system disturbances, and the head-pursuit guidance law based on an observer is proposed. Furthermore, this method is extended to a three-dimensional case. Finally, comparative simulation results further verify the superiority of the guidance laws designed in this article.

Direct simulation of evolution and control of three-dimensional instabilities in attachment-line boundary layers

1995 ◽  
Vol 291 ◽  
pp. 369-392 ◽  
Author(s):  
Ronald D. Joslin
Keyword(s):  
Boundary Layer ◽  
Stokes Equations ◽  
Three Dimensional ◽  
Plate Boundary ◽  
Navier Stokes ◽  
Two Dimensional ◽  
Computationally Efficient ◽  
Simulation Results ◽  
Dimensional Simulation ◽  
Attachment Line

The spatial evolution of three-dimensional disturbances in an attachment-line boundary layer is computed by direct numerical simulation of the unsteady, incompressible Navier–Stokes equations. Disturbances are introduced into the boundary layer by harmonic sources that involve unsteady suction and blowing through the wall. Various harmonic-source generators are implemented on or near the attachment line, and the disturbance evolutions are compared. Previous two-dimensional simulation results and nonparallel theory are compared with the present results. The three-dimensional simulation results for disturbances with quasi-two-dimensional features indicate growth rates of only a few percent larger than pure two-dimensional results; however, the results are close enough to enable the use of the more computationally efficient, two-dimensional approach. However, true three-dimensional disturbances are more likely in practice and are more stable than two-dimensional disturbances. Disturbances generated off (but near) the attachment line spread both away from and toward the attachment line as they evolve. The evolution pattern is comparable to wave packets in flat-plate boundary-layer flows. Suction stabilizes the quasi-two-dimensional attachment-line instabilities, and blowing destabilizes these instabilities; these results qualitatively agree with the theory. Furthermore, suction stabilizes the disturbances that develop off the attachment line. Clearly, disturbances that are generated near the attachment line can supply energy to attachment-line instabilities, but suction can be used to stabilize these instabilities.

scholarly journals Influence of Electric Field Coupling Model on the Simulated Performances of a GaN Based Planar Nanodevice

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
K. Y. Xu ◽  
Z. N. Wang ◽  
Y. N. Wang ◽  
J. W. Xiong ◽  
G. Wang
Keyword(s):  
Electric Field ◽  
3D Model ◽  
Second Harmonic ◽  
Strong Electric Field ◽  
Three Dimensional ◽  
Harmonic Oscillation ◽  
Two Dimensional ◽  
Dc Bias ◽  
Simulation Results ◽  
2D Model

The performances of a two-dimensional electron gas (2DEG) based planar nanodevice are studied by a two-dimensional-three-dimensional (2D-3D) combined model and an entirely 2D model. In both models, 2DEGs are depicted by 2D ensemble Monte Carlo (EMC) method. However electric field distributions in the devices are obtained by self-consistently solving 2D and 3D Poisson equations for the 2D model and the 2D-3D model, respectively. Simulation results obtained by both models are almost the same at low bias while showing distinguished differences at high bias. The 2D model predicts larger output current and slightly higher threshold voltage of Gunn oscillations. Although the fundamental frequencies of current oscillations obtained by both models are similar, the deviation of wave shape from sinusoidal waveform obtained by the 2D model is more serious than that obtained by 2D-3D model. Moreover, results obtained by the 2D model are more sensitive both to the bias conditions and to the change of device parameters. Interestingly, a look-like second harmonic oscillation has been observed at DC bias. We contribute the origin of divergences in simulation results to the different coupling path of electric field in the two models. And the second-harmonic oscillations at DC bias should be the result of the appearance of concomitant oscillations beside the channel excited by strong electric-field effects.

Research on Buckling Mechanism of U Type Steel Support’s Pinnas Based on ANSYS

2012 ◽  
Vol 466-467 ◽  
pp. 1271-1274
Author(s):  
Jian Zhuang Liu ◽  
Jia Li ◽  
Li Gan ◽  
Fang Fang Du
Keyword(s):  
Stress Distribution ◽  
Cross Section ◽  
Coal Mine ◽  
Optimization Design ◽  
Three Dimensional ◽  
Two Dimensional ◽  
Type Steel ◽  
Buckling Failure ◽  
Simulation Results ◽  
Three Dimensional Models

The prevenient mechanical research on U type steel support focuses on two dimensional analysis in the installing plan. Interested in the buckling failure of U type steel support’s pinnas in one coal mine of Huainan Group, the authors build three dimensional models to stimulating 25U and 29U support. The appealing simulation results verify ANSYS’s 3-D computational capabilities about complicated section support. The main objective of their investigation has been to obtain some knowledge of the mechanism, stress distribution, and load magnitude in the support’s deforming. Further, the deviating longitudinal load play an accelerating deformation role on its distorting, which should be paied more attention to cross-section optimization, design of support parameters, and installing way of steel lacing.

The Numerical Simulation Research of Gas Entrainment Based on Three-Dimensional Model

2017 ◽  
Author(s):  
Yilin Zhang ◽  
Shanfang Huang
Keyword(s):  
Experimental Data ◽  
Mass Flow Rate ◽  
Cross Section ◽  
Flow Rate ◽  
Three Dimensional ◽  
Two Dimensional ◽  
Dimensional Model ◽  
Three Dimensional Model ◽  
Gas Entrainment ◽  
Simulation Results

Two kinds of three-dimensional model are built to simulate the gas entrainment process through a small break in the horizontal coolant pipe at the bottom of the stratified flow. The results were compared with the two-dimensional simulation results and the experimental data. In terms of the two-phase distribution, the simulation results agree well with the experimental data and show much superiority compared with the two-dimensional model. The results verify the reliability of model building, condition setting and calculating method qualitatively and quantitatively. In general, after gas entrainment, the average velocity over cross section increases obviously, but the mass flow rate decreases contrarily. This is because that void fraction meanwhile reduces the fluid density. In addition, it is found that the larger the void fraction of vapor is, the higher the average discharge velocity of the fracture cross-section fluid is. Besides, with the larger internal and external pressure difference, the gas volume fraction and the flow velocity in the break increase, resulting in the mass flow rate increasing along with them. However, since the critical height increases as well, the total loss amount of liquid in the stable effluent stage decreases, and the time before entrainment becomes shorter.

Sign in / Sign up

Export Citation Format

Share Document