The emerging two-dimensional(2D)membranes offer a promising way to improve the water desalination performance of traditional membranes.MXene/graphene oxide(GO) composite membrane are known for their high separation pe...The emerging two-dimensional(2D)membranes offer a promising way to improve the water desalination performance of traditional membranes.MXene/graphene oxide(GO) composite membrane are known for their high separation performance and structural stability.In this study,molecular simulations are performed to investigate the desalination performance of the 2D MXene/GO membrane.The results reveal that the surface of the MXene nanosheet could induce the formation of ordered water structures,thereby accelerating the water transport in the 2D membrane.The higher rejection rate would be found in MXene/GO membrane with a larger GO oxidation degree owing to the sterichindrance effect induced by the functional groups on the GO surface.Overall,the MXene/GO(20) membrane with the interlayer spacing of 0.9 nm shows the highest water permeability(37.22×10^(-7)L·m^(-1)·h^(-1)·bar^(-1),1 bar=0.1 MPa)and a salt rejection of 100%.The results could provide theoretical insights for developing 2D membranes for water desalination.展开更多
Instead of the capillary plasma generator(CPG),a discharge rod plasma generator(DRPG)is used in the30 mm electrothermal-chemical(ETC)gun to improve the ignition uniformity of the solid propellant.An axisymmetric two-d...Instead of the capillary plasma generator(CPG),a discharge rod plasma generator(DRPG)is used in the30 mm electrothermal-chemical(ETC)gun to improve the ignition uniformity of the solid propellant.An axisymmetric two-dimensional interior ballistics model of the solid propellant ETC gun(2D-IB-SPETCG)is presented to describe the process of the ETC launch.Both calculated pressure and projectile muzzle velocity accord well with the experimental results.The feasibility of the 2D-IB-SPETCG model is proved.Depending on the experimental data and initial parameters,detailed distribution of the ballistics parameters can be simulated.With the distribution of pressure and temperature of the gas phase and the propellant,the influence of plasma during the ignition process can be analyzed.Because of the radial flowing plasma,the propellant in the area of the DRPG is ignited within 0.01 ms,while all propellant in the chamber is ignited within 0.09 ms.The radial ignition delay time is much less than the axial delay time.During the ignition process,the radial pressure difference is less than 5 MPa at the place 0.025 m away from the breech.The radial ignition uniformity is proved.The temperature of the gas increases from several thousand K(conventional ignition)to several ten thousand K(plasma ignition).Compare the distribution of the density and temperature of the gas,we know that low density and high temperature gas appears near the exits of the DRPG,while high density and low temperature gas appears at the wall near the breech.The simulation of the 2D-IB-SPETCG model is an effective way to investigate the interior ballistics process of the ETC launch.The 2D-IB-SPETC model can be used for prediction and improvement of experiments.展开更多
Owing to their rolling friction,two-dimensional piston pumps are highly suitable as power components for electro-hydrostatic actuators(EHAs).These pumps are particularly advantageous for applications requiring high ef...Owing to their rolling friction,two-dimensional piston pumps are highly suitable as power components for electro-hydrostatic actuators(EHAs).These pumps are particularly advantageous for applications requiring high efficiency and reliability.However,the ambiguity surrounding the output flow characteristics of individual two-dimensional pumps poses a significant challenge in achieving precise closed-loop control of the EHA positions.To address this issue,this study established a comprehensive numerical model that included gap leakage to analyze the impact of leakage on the output flow characteristics of a two-dimensional piston pump.The validity of the numerical analysis was indirectly confirmed through meticulous measurements of the leakage and volumetric efficiency,ensuring robust results.The research findings indicated that,at lower pump speeds,leakage significantly affected the output flow rate,leading to potential inefficiencies in the system.Conversely,at higher rotational speeds,the impact of leakage was less pronounced,implying that the influence of leakage on the pump outlet flow must be carefully considered and managed for EHAs to perform position servo control.Additionally,the research demonstrates that two-dimensional motion does not have a unique or additional effect on pump leakage,thus simplifying the design considerations.Finally,the study concluded that maintaining an oil-filled leakage environment is beneficial because it helps reduce the impact of leakage and enhances the overall volumetric efficiency of the pump system.展开更多
Perovskite/silicon(Si) tandem solar cells have been recognized as the next-generation photovoltaic technology with efficiency over 30% and low cost. However, the intrinsic instability of traditional three-dimensional(...Perovskite/silicon(Si) tandem solar cells have been recognized as the next-generation photovoltaic technology with efficiency over 30% and low cost. However, the intrinsic instability of traditional three-dimensional(3D) hybrid perovskite seriously hinders the lifetimes of tandem devices. In this work, the quasi-two-dimensional(2D)(BA)_(2)(MA)_(n-1)Pbn I_(3n+1)(n = 1, 2, 3, 4, 5)(where MA denotes methylammonium and BA represents butylammonium), with senior stability and wider bandgap, are first used as an absorber of semitransparent top perovskite solar cells(PSCs) to construct a fourterminal(4T) tandem devices with a bottom Si-heterojunction cell. The device model is established by Silvaco Atlas based on experimental parameters. Simulation results show that in the optimized tandem device, the top cell(n = 4) obtains a power conversion efficiency(PCE) of 17.39% and the Si bottom cell shows a PCE of 11.44%, thus an overall PCE of 28.83%. Furthermore, by introducing a 90-nm lithium fluoride(LiF) anti-reflection layer to reduce the surface reflection loss, the current density(J_(sc)) of the top cell is enhanced from 15.56 m A/cm^(2) to 17.09 m A/cm^(2), the corresponding PCE reaches 19.05%, and the tandem PCE increases to 30.58%. Simultaneously, in the cases of n = 3, 4, and 5, all the tandem PCEs exceed the limiting theoretical efficiency of Si cells. Therefore, the 4T quasi-2D perovskite/Si devices provide a more cost-effective tandem strategy and long-term stability solutions.展开更多
The characteristics of a collisional dual frequency （DF） sheath near an electrode with a cylindrical hole are studied by utilizing a two-dimensional model which includes time-dependent fluid equations coupled with t...The characteristics of a collisional dual frequency （DF） sheath near an electrode with a cylindrical hole are studied by utilizing a two-dimensional model which includes time-dependent fluid equations coupled with the Poisson equation and an equivalent-circuit model, The effects of the gas pressure on the two-dimensional profiles of the potential, electric field, ion fluid velocity in a DF sheath are investigated. The simulation results show that the cylindrical hole on the electrode has a significant influence on the DF sheath structure, i.e., the sheath profile tends to wrap around the contour of the hole feature. Moreover, it is shown that the structure of the DF sheath is different from that of a single frequency （SF） sheath because the profile of the DF sheath is modulated by the combination of the high and low frequency sources. In addition the characteristics of the DF sheath are obviously affected by the collisional effects in the DF sheath.展开更多
The characteristics of collisional radio-frequency (rf) sheath dynamics over an elec-trode with a cylindrical hole is simulated by means of a self-consistent model which consists of two-dimensional time-dependent flui...The characteristics of collisional radio-frequency (rf) sheath dynamics over an elec-trode with a cylindrical hole is simulated by means of a self-consistent model which consists of two-dimensional time-dependent fluid equations coupled with Poisson equation. In addition, an equivalent-circuit model is coupled to the fluid equations in order to self-consistently determine re-lationship between the instantaneous potential at the rf-biased electrode and the sheath thickness. Two-dimensional profiles of the potential, the ion fluid velocity, and the distributions of the ion and electron densities within the sheath are computed under various discharge conditions, such as the discharge powers and the gas pressures. The results show that the existence of the cylindrical hole on the electrode significantly affects the sheath structure and generates a potential trap in the horizontal direction, which is particularly strong when the sheath thickness is comparable to the depth of the hole. Moreover, it is found that the collisional effects have a significant influence on the sheath characteristics.展开更多
This study deals with the general numerical model to simulate the two-dimensional tidal flow, flooding wave (long wave) and shallow water waves (short wave). The foundational model is based on nonlinear Boussinesq equ...This study deals with the general numerical model to simulate the two-dimensional tidal flow, flooding wave (long wave) and shallow water waves (short wave). The foundational model is based on nonlinear Boussinesq equations. Numerical method for modelling the short waves is investigated in detail. The forces, such as Coriolis forces, wind stress, atmosphere and bottom friction, are considered. A two-dimensional implicit difference scheme of Boussinesq equations is proposed. The low-reflection outflow open boundary is suggested. By means of this model,both velocity fields of circulation current in a channel with step expansion and the wave diffraction behind a semi-infinite breakwater are computed, and the results are satisfactory.展开更多
A two-dimensional self-consistent fluid model is employed to investigate radio-frequency process parameters on the plasma properties in Ar microdischarges. The neutral gas density and temperature balance equations are...A two-dimensional self-consistent fluid model is employed to investigate radio-frequency process parameters on the plasma properties in Ar microdischarges. The neutral gas density and temperature balance equations are taken into account. We mainly investigate the effect of the electrode gap on the spatial distribution of the electron density and electron temperature profiles, due to a mode transition from the regime（secondary electrons emission is responsible for the significant ionization） to the regime（sheath oscillations and bulk electrons are responsible for sustaining discharge） induced by a sudden decrease of electron density and electron temperature.The pressure, radio-frequency sources frequency and voltage effects on the electron density are also elaborately investigated.展开更多
Dynamic infrared scene simulation is for discovering and solving the problems encountered in designing, developing and manufacturing infrared imaging guidance weapons. The infrared scene simulation is explored by usin...Dynamic infrared scene simulation is for discovering and solving the problems encountered in designing, developing and manufacturing infrared imaging guidance weapons. The infrared scene simulation is explored by using the digital grayscale modulation method. The infrared image modulation model of a digital micro-mirror device （DMD） is established and then the infrared scene simulator prototype which is based on DMD grayscale modulation is developed. To evaluate its main parameters such as resolution, contrast, minimum temperature difference, gray scale, various DMD subsystems such as signal decoding, image normalization, synchronization drive, pulse width modulation （PWM） and DMD chips are designed. The infrared scene simulator is tested on a certain infrared missile seeker. The test results show preliminarily that the infrared scene simulator has high gray scale, small geometrical distortion and highly resolvable imaging resolution and contrast and yields high-fidelity images, thus being able to meet the requirements for the infrared scene simulation inside a laboratory.展开更多
Realistic simulation of underwater scene is always difficult because of the special and complex vision effects in underwater space. Seabed is an important part of underwater environment. This paper describes the metho...Realistic simulation of underwater scene is always difficult because of the special and complex vision effects in underwater space. Seabed is an important part of underwater environment. This paper describes the methods for seabed scene simulation based on OpenGL. It includes construction of fluctuant terrain based on the random sinusoidal algorithm, simulation of seabed flicker effect by means of circular texture mapping and generation of turbidity effect by using fog techniques. For the application based on the leading high level 3D development environment - Vega, underwater scene simulation is still a difficulty since there is no module for it. Rased on the analysis of Vega software and the research on seabed scene simulation methods, a Vega extending module named 'Underwater Space' was created through developing module class and extending lynx interface. The module class was designed through developing DLL written in C + + . The Lynx was extended through developing keyword configure file, GUI configure file and lynx plug-in DLL. The problem that Vega can't simulate underwater space, is elementarily resolved. The results show that this module is efficient, easy using, and the seabed scene images are vivid.展开更多
Two-dimensional shear wave elastography(2D-SWE)is used in the clinical setting for observation of the liver.Unfortunately,a wide spectrum of artifactual images are frequently encountered in 2D-SWE,the precise mechanis...Two-dimensional shear wave elastography(2D-SWE)is used in the clinical setting for observation of the liver.Unfortunately,a wide spectrum of artifactual images are frequently encountered in 2D-SWE,the precise mechanisms of which remain incompletely understood.This review was designed to present many of the artifactual images seen in 2D-SWE of the liver and to analyze them by computer simulation models that support clinical observations.Our computer simulations yielded the following suggestions:(1)When performing 2D-SWE in patients with chronic hepatic disease,especially liver cirrhosis,it is recommended to measure shear wave values through the least irregular hepatic surface;(2)The most useful 2D-SWE in patients with focal lesion will detect lesions that are poorly visible on B-mode ultrasound and will differentiate true tumors from pseudo-tumors(e.g.,irregular fatty change);and(3)Measurement of shear wave values in the area posterior to a focal lesion must be avoided.展开更多
The adaptive mesh refinement （AMR） method is applied in the 2-D Euler multi-component elasticplastic hydrodynamics code （MEPH2Y）. It is applied on detonation. Firstly, the AMR method is described, including a cons...The adaptive mesh refinement （AMR） method is applied in the 2-D Euler multi-component elasticplastic hydrodynamics code （MEPH2Y）. It is applied on detonation. Firstly, the AMR method is described, including a conservative spatial interpolation, the time integration methodology with the adapitve time increment and an adaptive computational region method. The advantage of AMR technique is exhibited by numerical examples, including the 1-D C-J detonation and the 2-D implosion ignited from a single point. Results show that AMR can promote the computational efficiency, keeping the accuracy in interesting regions.展开更多
Creating proper 3D models plays an important pole in the development of scene simulation system based on multigen creator and Vega software. However, it is very difficult to construct complex structures by multigen cr...Creating proper 3D models plays an important pole in the development of scene simulation system based on multigen creator and Vega software. However, it is very difficult to construct complex structures by multigen creator. In this paper, an approach is proposed which is utilizing 3dsmax as assistant modeling software. 3D models developed in 3dsmax could be saved in 3ds format and then imported into multigen creator software. The models are revised and then saved in fit format by creator. For reducing model＇s data, simplification strategy is proposed. The problem of constructing complex models in creator is solved smoothly. In the development of digital rocket simulation project, the models constructed by this method have good visual effect, small size, and could be driven by Vega correctly.展开更多
In order to improve the English online courses teaching scene adaptability, optimize the online English teaching mode, improve the quality of English teaching, an English online course teaching platform is proposed ba...In order to improve the English online courses teaching scene adaptability, optimize the online English teaching mode, improve the quality of English teaching, an English online course teaching platform is proposed based on scene simulation. B/S client communication protocol is constructed in network transport layer, and the scene simulation model of English Online Course Teaching is established, online English teaching platform designed in this paper is constructed based on the sensing layer, network layer and application layer. A data processing center is constructed in the B/S structure and the network environment, Open Core kernel is used to realize the optimization of teaching model of English online courses, improve the teaching platform of online courses, and improve the scene adaptation ability. The test results show that the platform for online English teaching has better independent learning ability, the effectiveness of online English course teaching is better, test objects have higher satisfaction with English Online Course Teaching.展开更多
Infrared scene simulation has extensive applications in military and civil fields. Based on a certain experimental environment,object-oriented graphics rendering engine（ OGRE） is utilized to simulate a real three-di...Infrared scene simulation has extensive applications in military and civil fields. Based on a certain experimental environment,object-oriented graphics rendering engine（ OGRE） is utilized to simulate a real three-dimensional infrared complex scene. First,the target radiation of each part is calculated based on our experimental data. Then through the analysis of the radiation characteristics of targets and related material,an infrared texture library is established and the 3ds Max software is applied to establish an infrared radiation model.Finally,a real complex infrared scene is created by using the OGRE engine image rendering technology and graphic processing unit（ GPU） programmable pipeline technology. The results show that the simulation images are very similar to real images and are good supplements to real data.展开更多
The Ablowitz-Ladik equation is a very important model in nonlinear mathematical physics. In this paper, the hyper- bolic function solitary wave solutions, the trigonometric function periodic wave solutions, and the ra...The Ablowitz-Ladik equation is a very important model in nonlinear mathematical physics. In this paper, the hyper- bolic function solitary wave solutions, the trigonometric function periodic wave solutions, and the rational wave solutions with more arbitrary parameters of two-dimensional Ablowitz-Ladik equation are derived by using the （GI/G）-expansion method, and the effects of the parameters （including the coupling constant and other parameters） on the linear stability of the exact solutions are analysed and numerically simulated.展开更多
Objective: to observe the effectiveness of scene simulation teaching method in surgical nursing practice. Methods: in September of 1950s, the residents of our hospital were randomly divided into two groups. The contro...Objective: to observe the effectiveness of scene simulation teaching method in surgical nursing practice. Methods: in September of 1950s, the residents of our hospital were randomly divided into two groups. The control group (n30) used traditional teaching method, while the research group (n30) used simulated situational teaching method. Results: the theoretical score of the research group was (87.58-5.78) and that of the control group was (73.12-4.86). The scores of professional skills and comprehensive accomplishment of the research group were higher than those of the control group, with statistical significance (p 0.05). The satisfaction of the study group and the control group was 96.7% and 73.3% respectively, with significant difference between the two groups (p 0.05). Conclusion: scene simulation teaching method in surgical nursing practice can effectively improve students assessment results, help students to master the corresponding nursing skills, and has the value of popularization and application.展开更多
To fulfill the training requirements for the daily operations of multirotor unmanned aerial vehicles(UAVs)clusters,a UAV cluster collaborative task integrated simulation platform(UAV-TISP)was developed.The platform in...To fulfill the training requirements for the daily operations of multirotor unmanned aerial vehicles(UAVs)clusters,a UAV cluster collaborative task integrated simulation platform(UAV-TISP)was developed.The platform integrates a suite of hardware and software to simulate a range of collaborative UAV cluster operation scenarios.It features modules for collaborative task planning,UAV cluster simulations,and tactical monitoring.The platform significantly reduces training costs by eliminating physical drone dependencies while offering a flexible environment for testing swarm algorithms.UAV-TISP supports both individual UAV and swarm operations,incorporating high-fidelity flight dynamics,real-time communication via user datagram protocol(UDP),and collision avoidance strategies.Utilizing the OSGEarth engine,it enables dynamic 3D environment visualization and scenario customization.Three key task scenarios-route flight,formation reconstruction,and formation transformation-were tested to validate the platform’s efficacy.Results demonstrated robust formation maintenance,adaptive collision avoidance,and seamless task execution.Comparative analysis with Gazebo Sim revealed lower trajectory deviations in UAV-TISP,highlighting its superior accuracy in simulating real-world flight dynamics.Future work will focus on enhancing scalability for diverse UAV models,optimizing swarm networking under communication constraints,and expanding mission scenarios.UAV-TISP serves as a versatile tool for both operational training and advanced algorithm development in UAV cluster applications.展开更多
基金supported by the National Natural Science Foundation of China(22078251,21706197)the Open Project of Hubei Key Laboratory of Novel Reactor and Green Chemical Technology(NRG202407)+1 种基金the Ministry-of-Education,Key Laboratory for the Synthesis and Application of Organic Functional Molecules(KLSAOFM2511)the Graduate Innovative Fund of Wuhan Institute of Technology(CX2023024)。
文摘The emerging two-dimensional(2D)membranes offer a promising way to improve the water desalination performance of traditional membranes.MXene/graphene oxide(GO) composite membrane are known for their high separation performance and structural stability.In this study,molecular simulations are performed to investigate the desalination performance of the 2D MXene/GO membrane.The results reveal that the surface of the MXene nanosheet could induce the formation of ordered water structures,thereby accelerating the water transport in the 2D membrane.The higher rejection rate would be found in MXene/GO membrane with a larger GO oxidation degree owing to the sterichindrance effect induced by the functional groups on the GO surface.Overall,the MXene/GO(20) membrane with the interlayer spacing of 0.9 nm shows the highest water permeability(37.22×10^(-7)L·m^(-1)·h^(-1)·bar^(-1),1 bar=0.1 MPa)and a salt rejection of 100%.The results could provide theoretical insights for developing 2D membranes for water desalination.
文摘Instead of the capillary plasma generator(CPG),a discharge rod plasma generator(DRPG)is used in the30 mm electrothermal-chemical(ETC)gun to improve the ignition uniformity of the solid propellant.An axisymmetric two-dimensional interior ballistics model of the solid propellant ETC gun(2D-IB-SPETCG)is presented to describe the process of the ETC launch.Both calculated pressure and projectile muzzle velocity accord well with the experimental results.The feasibility of the 2D-IB-SPETCG model is proved.Depending on the experimental data and initial parameters,detailed distribution of the ballistics parameters can be simulated.With the distribution of pressure and temperature of the gas phase and the propellant,the influence of plasma during the ignition process can be analyzed.Because of the radial flowing plasma,the propellant in the area of the DRPG is ignited within 0.01 ms,while all propellant in the chamber is ignited within 0.09 ms.The radial ignition delay time is much less than the axial delay time.During the ignition process,the radial pressure difference is less than 5 MPa at the place 0.025 m away from the breech.The radial ignition uniformity is proved.The temperature of the gas increases from several thousand K(conventional ignition)to several ten thousand K(plasma ignition).Compare the distribution of the density and temperature of the gas,we know that low density and high temperature gas appears near the exits of the DRPG,while high density and low temperature gas appears at the wall near the breech.The simulation of the 2D-IB-SPETCG model is an effective way to investigate the interior ballistics process of the ETC launch.The 2D-IB-SPETC model can be used for prediction and improvement of experiments.
基金Supported by National Natural Science Foundation of China(Grant No.52205072).
文摘Owing to their rolling friction,two-dimensional piston pumps are highly suitable as power components for electro-hydrostatic actuators(EHAs).These pumps are particularly advantageous for applications requiring high efficiency and reliability.However,the ambiguity surrounding the output flow characteristics of individual two-dimensional pumps poses a significant challenge in achieving precise closed-loop control of the EHA positions.To address this issue,this study established a comprehensive numerical model that included gap leakage to analyze the impact of leakage on the output flow characteristics of a two-dimensional piston pump.The validity of the numerical analysis was indirectly confirmed through meticulous measurements of the leakage and volumetric efficiency,ensuring robust results.The research findings indicated that,at lower pump speeds,leakage significantly affected the output flow rate,leading to potential inefficiencies in the system.Conversely,at higher rotational speeds,the impact of leakage was less pronounced,implying that the influence of leakage on the pump outlet flow must be carefully considered and managed for EHAs to perform position servo control.Additionally,the research demonstrates that two-dimensional motion does not have a unique or additional effect on pump leakage,thus simplifying the design considerations.Finally,the study concluded that maintaining an oil-filled leakage environment is beneficial because it helps reduce the impact of leakage and enhances the overall volumetric efficiency of the pump system.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 62004151, 62274126, 62274126, 61874083, and 61804113)the China Postdoctoral Science Foundation (Grant No. 2020T130490)。
文摘Perovskite/silicon(Si) tandem solar cells have been recognized as the next-generation photovoltaic technology with efficiency over 30% and low cost. However, the intrinsic instability of traditional three-dimensional(3D) hybrid perovskite seriously hinders the lifetimes of tandem devices. In this work, the quasi-two-dimensional(2D)(BA)_(2)(MA)_(n-1)Pbn I_(3n+1)(n = 1, 2, 3, 4, 5)(where MA denotes methylammonium and BA represents butylammonium), with senior stability and wider bandgap, are first used as an absorber of semitransparent top perovskite solar cells(PSCs) to construct a fourterminal(4T) tandem devices with a bottom Si-heterojunction cell. The device model is established by Silvaco Atlas based on experimental parameters. Simulation results show that in the optimized tandem device, the top cell(n = 4) obtains a power conversion efficiency(PCE) of 17.39% and the Si bottom cell shows a PCE of 11.44%, thus an overall PCE of 28.83%. Furthermore, by introducing a 90-nm lithium fluoride(LiF) anti-reflection layer to reduce the surface reflection loss, the current density(J_(sc)) of the top cell is enhanced from 15.56 m A/cm^(2) to 17.09 m A/cm^(2), the corresponding PCE reaches 19.05%, and the tandem PCE increases to 30.58%. Simultaneously, in the cases of n = 3, 4, and 5, all the tandem PCEs exceed the limiting theoretical efficiency of Si cells. Therefore, the 4T quasi-2D perovskite/Si devices provide a more cost-effective tandem strategy and long-term stability solutions.
基金supported by National Natural Science Foundation of China (Nos.10635010,10572035)
文摘The characteristics of a collisional dual frequency （DF） sheath near an electrode with a cylindrical hole are studied by utilizing a two-dimensional model which includes time-dependent fluid equations coupled with the Poisson equation and an equivalent-circuit model, The effects of the gas pressure on the two-dimensional profiles of the potential, electric field, ion fluid velocity in a DF sheath are investigated. The simulation results show that the cylindrical hole on the electrode has a significant influence on the DF sheath structure, i.e., the sheath profile tends to wrap around the contour of the hole feature. Moreover, it is shown that the structure of the DF sheath is different from that of a single frequency （SF） sheath because the profile of the DF sheath is modulated by the combination of the high and low frequency sources. In addition the characteristics of the DF sheath are obviously affected by the collisional effects in the DF sheath.
基金The project supported by the National Natural Science Foundation of China(No.19975008 and 10275009)and by MOEC (Ministry of Education,China)Grant for Cross-Century Excellent ScholarSupport from the Natural Sciences and Engineering Research Council of C
文摘The characteristics of collisional radio-frequency (rf) sheath dynamics over an elec-trode with a cylindrical hole is simulated by means of a self-consistent model which consists of two-dimensional time-dependent fluid equations coupled with Poisson equation. In addition, an equivalent-circuit model is coupled to the fluid equations in order to self-consistently determine re-lationship between the instantaneous potential at the rf-biased electrode and the sheath thickness. Two-dimensional profiles of the potential, the ion fluid velocity, and the distributions of the ion and electron densities within the sheath are computed under various discharge conditions, such as the discharge powers and the gas pressures. The results show that the existence of the cylindrical hole on the electrode significantly affects the sheath structure and generates a potential trap in the horizontal direction, which is particularly strong when the sheath thickness is comparable to the depth of the hole. Moreover, it is found that the collisional effects have a significant influence on the sheath characteristics.
基金Supported by the Fund of National Nature Sciences of China
文摘This study deals with the general numerical model to simulate the two-dimensional tidal flow, flooding wave (long wave) and shallow water waves (short wave). The foundational model is based on nonlinear Boussinesq equations. Numerical method for modelling the short waves is investigated in detail. The forces, such as Coriolis forces, wind stress, atmosphere and bottom friction, are considered. A two-dimensional implicit difference scheme of Boussinesq equations is proposed. The low-reflection outflow open boundary is suggested. By means of this model,both velocity fields of circulation current in a channel with step expansion and the wave diffraction behind a semi-infinite breakwater are computed, and the results are satisfactory.
基金Supported by the Fundamental Research Funds in Heilongjiang Provincial Universities of China under Grant No 135209312
文摘A two-dimensional self-consistent fluid model is employed to investigate radio-frequency process parameters on the plasma properties in Ar microdischarges. The neutral gas density and temperature balance equations are taken into account. We mainly investigate the effect of the electrode gap on the spatial distribution of the electron density and electron temperature profiles, due to a mode transition from the regime（secondary electrons emission is responsible for the significant ionization） to the regime（sheath oscillations and bulk electrons are responsible for sustaining discharge） induced by a sudden decrease of electron density and electron temperature.The pressure, radio-frequency sources frequency and voltage effects on the electron density are also elaborately investigated.
基金co-supported by China Postdoctoral Science Foundation (20090461314)
文摘Dynamic infrared scene simulation is for discovering and solving the problems encountered in designing, developing and manufacturing infrared imaging guidance weapons. The infrared scene simulation is explored by using the digital grayscale modulation method. The infrared image modulation model of a digital micro-mirror device （DMD） is established and then the infrared scene simulator prototype which is based on DMD grayscale modulation is developed. To evaluate its main parameters such as resolution, contrast, minimum temperature difference, gray scale, various DMD subsystems such as signal decoding, image normalization, synchronization drive, pulse width modulation （PWM） and DMD chips are designed. The infrared scene simulator is tested on a certain infrared missile seeker. The test results show preliminarily that the infrared scene simulator has high gray scale, small geometrical distortion and highly resolvable imaging resolution and contrast and yields high-fidelity images, thus being able to meet the requirements for the infrared scene simulation inside a laboratory.
基金the National Defense Pre-research Foundation(51404040203)
文摘Realistic simulation of underwater scene is always difficult because of the special and complex vision effects in underwater space. Seabed is an important part of underwater environment. This paper describes the methods for seabed scene simulation based on OpenGL. It includes construction of fluctuant terrain based on the random sinusoidal algorithm, simulation of seabed flicker effect by means of circular texture mapping and generation of turbidity effect by using fog techniques. For the application based on the leading high level 3D development environment - Vega, underwater scene simulation is still a difficulty since there is no module for it. Rased on the analysis of Vega software and the research on seabed scene simulation methods, a Vega extending module named 'Underwater Space' was created through developing module class and extending lynx interface. The module class was designed through developing DLL written in C + + . The Lynx was extended through developing keyword configure file, GUI configure file and lynx plug-in DLL. The problem that Vega can't simulate underwater space, is elementarily resolved. The results show that this module is efficient, easy using, and the seabed scene images are vivid.
文摘Two-dimensional shear wave elastography(2D-SWE)is used in the clinical setting for observation of the liver.Unfortunately,a wide spectrum of artifactual images are frequently encountered in 2D-SWE,the precise mechanisms of which remain incompletely understood.This review was designed to present many of the artifactual images seen in 2D-SWE of the liver and to analyze them by computer simulation models that support clinical observations.Our computer simulations yielded the following suggestions:(1)When performing 2D-SWE in patients with chronic hepatic disease,especially liver cirrhosis,it is recommended to measure shear wave values through the least irregular hepatic surface;(2)The most useful 2D-SWE in patients with focal lesion will detect lesions that are poorly visible on B-mode ultrasound and will differentiate true tumors from pseudo-tumors(e.g.,irregular fatty change);and(3)Measurement of shear wave values in the area posterior to a focal lesion must be avoided.
基金Sponsored by the National Natural Science Foundation of China(10676120)Laboratory of Computational Physics Foundation(9140C690101070C69)
文摘The adaptive mesh refinement （AMR） method is applied in the 2-D Euler multi-component elasticplastic hydrodynamics code （MEPH2Y）. It is applied on detonation. Firstly, the AMR method is described, including a conservative spatial interpolation, the time integration methodology with the adapitve time increment and an adaptive computational region method. The advantage of AMR technique is exhibited by numerical examples, including the 1-D C-J detonation and the 2-D implosion ignited from a single point. Results show that AMR can promote the computational efficiency, keeping the accuracy in interesting regions.
文摘Creating proper 3D models plays an important pole in the development of scene simulation system based on multigen creator and Vega software. However, it is very difficult to construct complex structures by multigen creator. In this paper, an approach is proposed which is utilizing 3dsmax as assistant modeling software. 3D models developed in 3dsmax could be saved in 3ds format and then imported into multigen creator software. The models are revised and then saved in fit format by creator. For reducing model＇s data, simplification strategy is proposed. The problem of constructing complex models in creator is solved smoothly. In the development of digital rocket simulation project, the models constructed by this method have good visual effect, small size, and could be driven by Vega correctly.
文摘In order to improve the English online courses teaching scene adaptability, optimize the online English teaching mode, improve the quality of English teaching, an English online course teaching platform is proposed based on scene simulation. B/S client communication protocol is constructed in network transport layer, and the scene simulation model of English Online Course Teaching is established, online English teaching platform designed in this paper is constructed based on the sensing layer, network layer and application layer. A data processing center is constructed in the B/S structure and the network environment, Open Core kernel is used to realize the optimization of teaching model of English online courses, improve the teaching platform of online courses, and improve the scene adaptation ability. The test results show that the platform for online English teaching has better independent learning ability, the effectiveness of online English course teaching is better, test objects have higher satisfaction with English Online Course Teaching.
基金Supported by the National Twelfth Five-Year Project(40405050303)
文摘Infrared scene simulation has extensive applications in military and civil fields. Based on a certain experimental environment,object-oriented graphics rendering engine（ OGRE） is utilized to simulate a real three-dimensional infrared complex scene. First,the target radiation of each part is calculated based on our experimental data. Then through the analysis of the radiation characteristics of targets and related material,an infrared texture library is established and the 3ds Max software is applied to establish an infrared radiation model.Finally,a real complex infrared scene is created by using the OGRE engine image rendering technology and graphic processing unit（ GPU） programmable pipeline technology. The results show that the simulation images are very similar to real images and are good supplements to real data.
基金Project supported by the Basic Science and the Front Technology Research Foundation of Henan Province,China(Grant Nos.092300410179 and122102210427)the Doctoral Scientific Research Foundation of Henan University of Science and Technology,China(Grant No.09001204)+1 种基金the Scientific Research Innovation Ability Cultivation Foundation of Henan University of Science and Technology,China(Grant No.011CX011)the Scientific Research Foundation of Henan University of Science and Technology(Grant No.2012QN011)
文摘The Ablowitz-Ladik equation is a very important model in nonlinear mathematical physics. In this paper, the hyper- bolic function solitary wave solutions, the trigonometric function periodic wave solutions, and the rational wave solutions with more arbitrary parameters of two-dimensional Ablowitz-Ladik equation are derived by using the （GI/G）-expansion method, and the effects of the parameters （including the coupling constant and other parameters） on the linear stability of the exact solutions are analysed and numerically simulated.
文摘Objective: to observe the effectiveness of scene simulation teaching method in surgical nursing practice. Methods: in September of 1950s, the residents of our hospital were randomly divided into two groups. The control group (n30) used traditional teaching method, while the research group (n30) used simulated situational teaching method. Results: the theoretical score of the research group was (87.58-5.78) and that of the control group was (73.12-4.86). The scores of professional skills and comprehensive accomplishment of the research group were higher than those of the control group, with statistical significance (p 0.05). The satisfaction of the study group and the control group was 96.7% and 73.3% respectively, with significant difference between the two groups (p 0.05). Conclusion: scene simulation teaching method in surgical nursing practice can effectively improve students assessment results, help students to master the corresponding nursing skills, and has the value of popularization and application.
文摘To fulfill the training requirements for the daily operations of multirotor unmanned aerial vehicles(UAVs)clusters,a UAV cluster collaborative task integrated simulation platform(UAV-TISP)was developed.The platform integrates a suite of hardware and software to simulate a range of collaborative UAV cluster operation scenarios.It features modules for collaborative task planning,UAV cluster simulations,and tactical monitoring.The platform significantly reduces training costs by eliminating physical drone dependencies while offering a flexible environment for testing swarm algorithms.UAV-TISP supports both individual UAV and swarm operations,incorporating high-fidelity flight dynamics,real-time communication via user datagram protocol(UDP),and collision avoidance strategies.Utilizing the OSGEarth engine,it enables dynamic 3D environment visualization and scenario customization.Three key task scenarios-route flight,formation reconstruction,and formation transformation-were tested to validate the platform’s efficacy.Results demonstrated robust formation maintenance,adaptive collision avoidance,and seamless task execution.Comparative analysis with Gazebo Sim revealed lower trajectory deviations in UAV-TISP,highlighting its superior accuracy in simulating real-world flight dynamics.Future work will focus on enhancing scalability for diverse UAV models,optimizing swarm networking under communication constraints,and expanding mission scenarios.UAV-TISP serves as a versatile tool for both operational training and advanced algorithm development in UAV cluster applications.
