Molecular simulation study of the microstructures and properties of pyridinium ionic liquid[HPy][BF_(4)]mixed with acetonitrile

The microstructures and thermodynamic properties of mixed systems comprising pyridinium ionic liquid[HPy][BF_(4)]and acetonitrile at different mole fractions were studied using molecular dynamics simulation in this work.The following properties were determined:density,self-diffusion coefficient,excess molar volume,and radial distribution function.The results show that with an increase in the mole fraction of[HPy][BF_(4)],the self-diffusion coefficient decreases.Additionally,the excess molar volume initially decreases,reaches a minimum,and then increases.The rules of radial distribution functions(RDFs)of characteristic atoms are different.With increasing the mole fraction of[HPy][BF_(4)],the first peak of the RDFs of HA1-F decreases,while that of CT6-CT6 rises at first and then decreases.This indicates that the solvent molecules affect the polar and non-polar regions of[HPy][BF_(4)]differently.

Simulation of multilayer homoepitaxial growth on Cu （100） surface

The processes of multilayer thin Cu films grown on Cu （100） surfaces at elevated temperature （250-400K） are simulated by mean of kinetic Monte Carlo （KMC） method, where the realistic growth model and physical parameters are used. The effects of small island （dimer and trimer） diffusion, edge diffusion along the islands, exchange of the adatom with an atom in the existing island, as well as mass transport between interlayers are included in the simulation model. Emphasis is placed on revealing the influence of the Ehrlic-Schwoebel （ES） barrier on growth mode and morphology during multilayer thin film growth. We present numerical evidence that the ES barrier does exist for the Cu/Cu（100） system and an ES barrier EB 〉 0.125eV is estimated from a comparison of the KMC simulation with the realistic experimental images. The transitions of growth modes with growth conditions and the influence of exchange barrier on growth mode are also investigated.

Numerical simulation of domain switching in multilayer ferroelectric actuators

Micromechanical finite element methods are developed based on a nonlinear constitutive model of ferroelectric polycrystals. Electromechanical behaviors ahead of an internal electrode tip are numerically simulated in multilayer ferroelectric actuators. Around the electrode edge, the nonuniform electric field generates a concentration of stress due to the incompatible strain as well as spontaneous strain. The preferred domain switching enhances the concentration of residual stress and may cause the actuators to crack. An electrically permeable crack emanating from an internal electrode is analyzed. A large scale domain switching zone is found in the vicinity of crack tips. The larger the actuating strain and electric field are, the larger the switching zone will be. The size of switching zone even reaches the scale of crack length with increasing electromechanical loading.

Molecular Simulation of Hydrogen Adsorption Density in Single-Walled Carbon Nanotubes and Multilayer Adsorption Mechanism

The adsorption of hydrogen onto single-walled carbon nanotubes (SWCNTs) was studied by molecular dynamics (MD) sim'lation. It was found that the hydrogen molecules distribute regularly inside and outside of the tube. Density distribution was computed for H2 molecule. Theoretical analysis of the result showed the multilayer adsorption mechanism of SWCNTs. The storage of H2 in SWCNTs is computed, which provides essential theoretical reference for further study of hydrogen adsorption in SWCNTs.

Simulation study of hydrogen sulfide removal in underground gas storage converted from the multilayered sour gas field

A simulation study was carried out to investigate the temporal evolution of H_(2)S in the Huangcaoxia underground gas storage (UGS), which is converted from a depleted sulfur-containing gas field. Based on the rock and fluid properties of the Huangcaoxia gas field, a multilayered model was built. The upper layer Jia-2 contains a high concentration of H_(2)S (27.2 g/m^(3)), and the lower layer Jia-1 contains a low concentration of H_(2)S (14.0 mg/m^(3)). There is also a low-permeability interlayer between Jia-1 and Jia-2. The multi-component fluid characterizations for Jia-1 and Jia-2 were implemented separately using the Peng-Robinson equation of state in order to perform the compositional simulation. The H_(2)S concentration gradually increased in a single cycle and peaked at the end of the production season. The peak H_(2)S concentration in each cycle showed a decreasing trend when the recovery factor (RF) of the gas field was lower than 70%. When the RF was above 70%, the peak H_(2)S concentration increased first and then decreased. A higher reservoir RF, a higher maximum working pressure, and a higher working gas ratio will lead to a higher H_(2)S removal efficiency. Similar to developing multi-layered petroleum fields, the operation of multilayered gas storage can also be divided into multi-layer commingled operation and independent operation for different layers. When the two layers are combined to build the storage, the sweet gas produced from Jia-1 can spontaneously mix with the sour gas produced from Jia-2 within the wellbore, which can significantly reduce the overall H_(2)S concentration in the wellstream. When the working gas volume is set constant, the allocation ratio between the two layers has little effect on the H_(2)S removal. After nine cycles, the produced gas’s H_(2)S concentration can be lowered to 20 mg/m^(3). Our study recommends combining the Jia-2 and Jia-1 layers to build the Huangcaoxia underground gas storage. This plan can quickly reduce the H_(2)S concentration of the produced gas to 20 mg/m^(3), thus meeting the gas export standards as well as the HSE (Health, Safety, and Environment) requirements in the field. This study helps the engineers understand the H_(2)S removal for sulfur-containing UGS as well as provides technical guidelines for converting other multilayered sour gas fields into underground storage sites.

Identification Simulation for Dynamical System Based on Genetic Algorithm and Recurrent Multilayer Neural Network

Identification simulation for dynamical system which is based on genetic algorithm (GA) and recurrent multilayer neural network (RMNN) is presented. In order to reduce the inputs of the model, RMNN which can remember and store some previous parameters is used for identifier. And for its high efficiency and optimization, genetic algorithm is introduced into training RMNN. Simulation results show the effectiveness of the proposed scheme. Under the same training algorithm, the identification performance of RMNN is superior to that of nonrecurrent multilayer neural network (NRMNN).

Quantitative Characterization and Dynamic Law of Interlayer Interference for Multilayer Commingled Production in Heavy Oil Reservoirs by Numerical Simulation

This paper moves one step forward to build?a?numerical model to research quantitative characterization and dynamic law for interlayer interference factor (IIF) in the multilayer reservoir which was heavy oil reservoirs and produced by directional wells. There are mainly four contributions of this paper to the existing body of literature. Firstly, an equivalent simulation method of the pseudo start pressure gradient (PSPG) is developed to quantitatively predict the value of?IIF?under different geological reservoir conditions. Secondly, the interlayer interference is extended in time, and the time period of the study extends from a water cut stage to the whole process from the oil well open to produce?a?high water cut. Thirdly, besides the conventional productivity interlayer interference factor (PIIF), a new parameter, that is, the oil recovery interlayer interference factor (RIIF) is put forward.?RIIF?can be used to evaluate the technical indexes of stratified development and multilayer co-production effectively. Fourthly,?the?effectsof various geological reservoir parameters such as reservoir permeability and crude oil viscosity, etc. on the?PIIF?and?RIIF’s?type curves?are?discussed in detail and the typical plate?is?plotted. The research results provide a foundation for the effective development of multilayer heavy oil reservoirs.

Numerical simulation of the blast wave of a multilayer composite charge

The numerical simulation of a blast wave of a multilayer composite charge is investigated.A calculation model of the near-field explosion and far-field propagation of the shock wave of a composite charge is established using the AUTODYN finite element program.Results of the near-field and far-field calculations of the shock wave respectively converge at cell sizes of 0.25-0.5 cm and 1-3 cm.The Euler--fluxcorrected transport solver is found to be suitable for the far-field calculation after mapping.A numerical simulation is conducted to study the formation,propagation,and interaction of the shock wave of the composite charge for different initiation modes.It is found that the initiation mode obviously affects the shock-wave waveform and pressure distribution of the composite charge.Additionally,it is found that the area of the overpressure distribution is greatest for internal and external simultaneous initiation,and the peak pressure of the shock wave exponentially decays,fitting the calculation formula of the peak overpressure attenuation under different initiation modes,which is obtained and verified by experiment.The difference between numerical and experimental results is less than 10%,and the peak overpressure of both internal and external initiation is 56.12% higher than that of central single-point initiation.

Monte Carlo Simulation on LED Graded-refractive-index Multilayer Encapsulation Structure

Light propagation in nanoparticle-loaded encapsulants is simulated based on the method of Monte Carlo,referring to the multilayer graded-refractive-index structure for LED encapsulants.And the influence of scattering coefficient on the transmittance is analyzed.The results show that the transmittance decreases with scattering coefficient.For a given number of layers,the encapsulants will yield maximum transmittance if the refractive index value of each layer is optimized.The nanoparticle-loaded encapsulant consists of multiple layers with refractive-index values that gradually decrease.The transmittance will be higher than that of traditional non-graded encapsulants,and will improve light extraction efficiency of LED.

NUMERICAL SIMULATION OF OIL MIGRATION-ACCUMULATION OF MULTILAYER AND ITS APPLICATION

From such actual conditions as the effects of fluid mechanics in porous media and three-dimensional geology characteristics, the mathematical model and a kind of modified method of second order splitting-up implicit iterative scheme were put forward. For the actual problem of Dongying hollow (single layer) and Huimin hollow (multilayer) of Shengli Petroleum Oil Field, this numerical simulation test and the actual conditions are basically coincident, thus the well-known problem has been solved.

EMF Antenna Exposure on a Multilayer Human Head Simulation for Alzheimer Disease Treatments

In this paper, we follow up with our preliminary biological studies that showed that Repeated electromagnetic field stimulation (REMFS) decreased the toxic amyloid-beta (Aβ) levels, which is considered to be the cause of Alzheimer’s disease (AD). The REMFS parameters of these exposures were a frequency of 64 MHz and a Specific absorption rate (SAR) of 0.4 to 0.9 W/Kg in primary human neuronal cultures. In this work, an electromagnetic field (EMF) model was simulated using high-frequency simulation system (HFSS/EMPro) software. Our goal was to achieve the EM parameters (EMF Frequency and SAR) required to decrease the toxic Aβ levels in our biological studies in a simulated human head. The simulations performed here will potentially lead to the successful development of an exposure system to treat Alzheimer’s disease patients. A popular VFH (very high frequency) patch microstrip antenna system was considered in the study. The selection was based on simple and easy construction and appropriateness to the VHF applications. The evaluation of the SAR and temperature distribution on the various head layers, including skin, fat, dura, the cerebrospinal (CSF), and grey matter, brain tissues, were determined for efficacy SAR and safety temperature increase on a simulated human head. Based on a current pulse of 1 A peak current fed to the antenna feeder, a maximum SAR of 0.6 W/Kg was achieved. A range of 0.4 to 0.6 SAR was observed over the various layers of the simulated human head. The initial design of the antenna indicated an antenna size in the order of 1 m in length and width, suggesting a stationary practical model for AD therapy. Future direction is given for wearable antenna and exposure system, featuring high efficiency and patient comfort.

On the Simulation of the Influence of Defects on Immersed Plane Periodic Multilayer Viscoelastic Media

This work deals with the study of a plane periodic multilayer structure in which the elementary stack consists of two plates in contact: one in aluminum (AL) and the other one in polyethylene (PE). These isotropic materials, present a high acoustic impedance contrast. The attenuation of the longitudinal and transverse waves is taken into account in the polyethylene but neglected in the aluminum plate. The effect of different defects is analyzed. Firstly, we focus on the effect of the presence of grease inclusion in the polyethylene plate (considering the two plates of the elementary stack in perfect contact). Secondly, the effect of disbond simulated by the insertion of a thin Teflon layer between the interfaces of the two layers constituting the elementary stack of the multilayer structure is investigated. Finally, the effect of the stacking sequences of the multilayer is analyzed. In order to obtain the effective acoustic parameters of polyethylene layer, allowing to evaluate the reflection and transmission coefficients using the stiffness matrix method developed by Rokhlin et al., four homogenization models are analyzed, then the best one to our configuration is chosen. The comparison of the simulation results is carried out.

Modelling, Simulation and Optimization of n-p-n-p Silicon Multilayer Solar Cells

We simulate the conception parameters of a model of a silicon multilayer solar cell. The cell is composed by four layers of opposite conductivities forming three junctions inside the cell. The electric contacts are tailored vertically to collect the minority carrier generated under illumination. We developed the equations giving the output power, the fill factor and the efficiency of the cell, taking into account the series resistances of each layer. We optimized, using MATLAB software, the thicknesses of the layers, the impurity concentration level and the distance between the electric contacts. We showed that the optimized photovoltaic structure, with the silicon properties published at the Ioffe institute website, gives an efficiency of 20.66%. The n-p-n-p silicon cell delivers a short circuit current Icc = 45.3 mA/cm2, an open circuit voltage V oc= 0.746 V and an output power of 28.5 mW/cm2. The corresponding fill factor is FF = 84.29%.

An extended HLA multilayer federation integration architecture for multidisciplinary collaborative simulation

The development of complex products is essentially concerned with multidisciplinary knowledge. Running on Internet, integration based on muhilayer federation architecture and dynamic reuse of simulation resources are the major difficulties for complex product collaborative design and simulation. Since the traditional Run-Time Infrastructure （RTI） is not good at supporting these new requirements, an extended high level architecture （HLA） multilayer federation integration architecture （MLFIA）, based on the resource management federation （RMF） and its supporting environment based Service-oriented architecture （SOA） and HLA （SOHLA） are proposed, The idea and realization of two key technologies, the dynamic creation of simulation federation based on RMF, TH RTI, an extensible HLA runtime infrastructure （RTI）, used at Internet are emphasized. Finally, an industry case about multiple unit （MU） is given.

Simulations of Tapered Channel in Multilayer Graphene as Reverse Osmosis Membrane for Desalination

Pressure-driven reverse osmosis membrane has important application in seawater desalination.Inspired by the structure of aquaporin,we established and studied the mechanism of the structure of multilayer graphene with tapered channels as reverse osmosis.The water flux of multilayer graphene with tapered channels was about 20%higher than that of parallel graphene channel.The flow resistance model was established,and the relationship between flow resistance and opening angles was clarified.The relationship between flow resistance and outlet size was also described.By means of molecular dynamics simulation,slip coefficients of multilayer graphene with tapered channel were obtained and verified by the contact angle of water.Results show that the permeability of graphene with tapered channel is about three orders of magnitude higher than that of commercial reverse osmosis membrane and the desalination rate is 100%.Temperature difference between the two sides of the tapered channel will promote the water flux positively.

Simulation of multilayer Cu/Pd（100） heteroepitaxial growth by pulse laser deposition

The heteroepitaxial growth of multilayer Cu/Pd（100） thin film via pulse laser deposition （PLD） at room temperature is simulated by using kinetic Monte Carlo （KMC） method with realistic physical parameters. The effects of mass transport between interlayers, edge diffusion of adatoms along the islands and instantaneous deposition are considered in the simulation model, Emphasis is placed on revealing the details of multilayer Cu/Pd（100） thin film growth and estimating the Ehrlich-Schwoebel （ES） barrier. It is shown that the instantaneous deposition in the PLD growth gives rise to the layer-by-layer growth mode, persisting up to about 9 monolayers （ML） of Cu/Pd（100）. The ES barriers of 0.08 ± 0.01 eV is estimated by comparing the KMC simulation results with the real scanning tunnelling microscopy （STM） measurements,

Simulation of Multilayer Silicon Thin Films Growth on Si(111) Surface

The homoepitaxial growth of multilayer Si thin film on Si(111) surfaces was simulated by Monte Carlo (MC) method with realistic growth model and physical parameters. Special emphasis was placed on revealing the influence of the Ehrlich-Schwoebel (ES) barrier on the growth modes and morphologies. It is evident that there exists the ES barrier during multilayer Si thin film growth on Si (111) surface, which is deduced from the incomplete layer-by-layer growth process in the realistic experiments. The ES barrier EB=0.1～0.125 eV is estimated from the three-dimensional (3D) MC simulation and compared with the experimental results.

Numerical simulation of temperature field in multilayer heterogeneity lamination laser soldering

A temperature field numerical simulation is carried out using the finite element method for laser soldering on PECT (piezoelectric ceramics transformer). A three dimensional model of laser soldering temperature field of multilayer materials is established. Then, the model was simplified in order to perform an efficient finite element analysis. Moreover, the temperature distribution characteristic in the laser soldering is investigated and verified by experiments. In all cases, the numerical results are in good agreement with the experimental measurements.

基于Plant Simulation的化纤自动落丝系统仿真实验分析

基于Plant Simulation软件,构建一种化纤自动落丝系统的3D数字化模型,对系统效率关键输入因子进行参数化设置,将系统各工位三维数字模型导入软件中建立层次化运动机构图形结构,并运用Simltalk语言实现三维动作仿真,通过基础物理参数设置,保证了仿真数字化模型与现实系统更具一致性。通过多级实验设计分析了系统影响因子对于系统效率的影响特性曲线,并进一步通过动态参数化实验方法,计算出双输入因子对系统效能影响的敏感度。该实验结果可为化纤自动落丝系统的建设成本控制与可行性分析提供指导,具有较好的工程应用价值。

基于Simulation X的多轴转向系统功能安全仿真分析

基于ISO 26262《道路车辆功能安全》的标准要求,对特种车的多轴电液转向系统进行分析,以提高系统的安全性和可靠性。运用Simulation X软件建立详细的多轴特种车仿真模型,通过模拟故障模式注入进行仿真试验。对仿真结果和数据进行分析,评估得到故障的严重性、暴露度和可控性,从而确定相应的汽车安全完整性等级。基于故障注入仿真的汽车功能安全分析方法,在系统早期设计阶段可以作为评估架构安全性的重要手段。