Numerical simulation of a sheet metal extrusion process by using thermal-mechanical coupling EAS FEM

The thermal-mechanical coupling finite element method(FEM)was usedto simulate a non-isothermal sheet metal extrusion process. On thebasis of the finite plasticity consistent with multiplicativedecomposition of the deformation gradient, the enhanced as- sumedstrain(EAS)FEM was applied to carry out the numerical simulation. Inorder to make the computation reliable ad avoid hour- glass mode inthe EAS element under large compressive strains, an alterative formof the original enhanced deformation gradient was employed. Inaddition, reduced factors were used in the computation of the elementlocal internal parameters and the enhanced part of elementalstiffness.

High Coupling Efficiency of the Fiber-Coupled Module Based on Photonic-Band-Crystal Laser Diodes

The coupling efficiency of the beam combination and the fiber-coupled module is limited due to the large vertical divergent angle of conventional semiconductor laser diodes. We present a high coupling efficiency module using photonic-band-crystal （PBC） laser diodes with narrow vertical divergent angles. Three PBC single-emitter laser diodes are combined into a fiber with core diameter of 105μm and numerical aperture of 0.22. A high coupling efficiency of 94.4% is achieved and the brightness is calculated to be 1.T MW/（cm2.sr） with the injection current of 8A.

A Component Selection Framework of Cohesion and Coupling Metrics

Component-based software engineering is concerned with the develop-ment of software that can satisfy the customer prerequisites through reuse or inde-pendent development.Coupling and cohesion measurements are primarily used to analyse the better software design quality,increase the reliability and reduced system software complexity.The complexity measurement of cohesion and coupling component to analyze the relationship between the component module.In this paper,proposed the component selection framework of Hexa-oval optimization algorithm for selecting the suitable components from the repository.It measures the interface density modules of coupling and cohesion in a modular software sys-tem.This cohesion measurement has been taken into two parameters for analyz-ing the result of complexity,with the help of low cohesion and high cohesion.In coupling measures between the component of inside parameters and outside parameters.Thefinal process of coupling and cohesion,the measured values were used for the average calculation of components parameter.This paper measures the complexity of direct and indirect interaction among the component as well as the proposed algorithm selecting the optimal component for the repository.The better result is observed for high cohesion and low coupling in compo-nent-based software engineering.

Discrete modulational instability and bright localized spin wave modes in easy-axis weak ferromagnetic spin chains involving the next-nearest-neighbor coupling

We report a theoretical work on the properties of modulational instability and bright type nonlinear localized modes in one-dimensional easy-axis weak ferromagnetic spin lattices involving next-nearest-neighbor couplings.With a linear stability analysis, we calculate the growth rates of the modulational instability, and plot the instability regions.When the strength of the next-nearest-neighbor coupling is large enough, two new asymmetric modulational instability regions appear near the boundary of the first Brillouin zone.Furthermore, analytical forms of the bright nonlinear localized modes are constructed by means of a quasi-discreteness approach.The influence of the next-nearest-neighbor coupling on the Brillouin zone center mode and boundary mode are discussed.In particular, we discover a reversal phenomenon of the propagation direction of the Brillouin zone boundary mode.

ANALYSIS OF SHAKEDOWN OF FG BREE PLATE SUBJECTED TO COUPLED THERMAL-MECHANICAL LOADINGS

The static and kinematic shakedown of a functionally graded （FG） Bree plate is analyzed. The plate is subjected to coupled constant mechanical load and cyclically varying temperature. The material is assumed linearly elastic and nonlinear isotropic hardening with elastic modulus,yield strength and the thermal expansion coeffcient varying exponentially through the thickness of the plate. The boundaries between the shakedown area and the areas of elasticity,incremental collapse and reversed plasticity are determined,respectively. The shakedown of the counterpart made of homogeneous material with average material properties is also analyzed. The comparison between the results obtained in the two cases exhibits distinct qualitative and quantitative difference,indicating the importance of shakedown analysis for FG structures. Since FG structures are usually used in the cases where severe coupled cyclic thermal and mechanical loadings are applied,the approach developed and the results obtained are significant for the analysis and design of such kind of structures.

Analysis of thermal-mechanical coupled characteristics of vehicle twin-tube shock absorber

A comprehensive model that included mechanical dynamics of the shock absorber coupled with its thermal properties was proposed innovatively.Moreover a thermal-mechanical coupled model which reflected the closed-loop positive feedback system was established by using MATLAB/SIMULINK,and some curves of shock absorber temperature rising characteristic were obtained by simulation ＆computation under several operating modes and different parameters conditions.Research results show that：shock absorber design parameters,external excitations,and thermo-physical properties parameter,such as oil density have effect on the shock absorber temperature rising characteristic.However other thermo-physical properties parameters,such as oil specific heat,cylinder density,cylinder specific heat,and cylinder thermal conductivity,have no effect on it.The results may be used for studying reliability design of the shock absorber.

Thermal-Mechanical Coupled FE Analysis for Rotary Shaft Seals

The aim of this paper is to model the steady-state condition of a rotary shaft seal (RSS) system. For this, an iterative thermal-mechanical algorithm was developed based on incremental finite element analyzes. The behavior of the seal’s rubber material was taken into account by a large-strain viscoelastic, so called generalized Maxwell model, based on Dynamic Mechanical Thermal Analyses (DMTA) and tensile measurements. The pre-loaded garter spring was modelled with a bilinear material model and the shaft was assumed to be linear elastic. The density, coefficient of thermal expansion and the thermal conductance of the materials were taken into consideration during simulation. The friction between the rotary shaft seal and the shaft was simplified and modelled as a constant parameter. The iterative algorithm was evaluated at two different times, right after assembly and 1 h after assembly, so that rubber material’s stress relaxation effects are also incorporated. The results show good correlation with the literature data, which state that the permissible temperature for NBR70 (nitrile butadiene rubber) material contacting with ~80 mm shaft diameter, rotating at 2600/min is 100°C. The results show 107°C and 104°C for the two iterations. The effect of friction induced temperature, changes the width of the contact area between the seal and the shaft, and significantly reduces the contact pressure.

Strip Waveguide Directional Coupling Modulator with Equivalent Refractive Index

The equivalent refractive index（ERI） method is employed to analyze the function of the strip waveguide directional coupling modulator（SWM）. Through deducing the diagnostic equation of the Exmn mode of the four-layer media film waveguide equivalent to the SWM,the transmission constant of the symmetrical mode of the positive phase and negative one and the coupling length of powerful transference are obtained. The veracity of ERI is validated with the example of Ex11 basal mode under conditions of comparing the three results of ERI,EIM and Marcatili.

An Improved Coupling of Numerical and Physical Models for Simulating Wave Propagation

An improved coupling of numerical and physical models for simulating 2D wave propagation is developed in this paper. In the proposed model, an unstructured finite element model （FEM） based Boussinesq equations is applied for the numerical wave simulation, and a 2D piston-type wavemaker is used for the physical wave generation. An innovative scheme combining fourth-order Lagrange interpolation and Runge-Kutta scheme is described for solving the coupling equation. A Transfer function modulation method is presented to minimize the errors induced from the hydrodynamic invalidity of the coupling model and/or the mechanical capability of the wavemaker in area where nonlinearities or dispersion predominate. The overall performance and applicability of the coupling model has been experimentally validated by accounting for both regular and irregular waves and varying bathymetry. Experimental results show that the proposed numerical scheme and transfer function modulation method are efficient for the data transfer from the numerical model to the physical model up to a deterministic level.

A study on coupling technique and implementation of the wave-circulation coupled model

The coupler is fundamental for a coupled model to realize complex interactions among component models.This paper focuses on the coupling process of Wave-Circulation(W-C) coupled model which consists of MASNUM(key laboratory of marine science and numerical modeling wave model)and POM(Princeton Ocean Model).The current coupling module of this coupled model is based on the inefficient I/O file,which has already become a performance bottleneck especially when the coupled model utilizes a large number of processes.To improve the performance of the W-C model,a flexible coupling module based on the model coupling toolkit(MCT) is designed and implemented to replace the current I/O file coupling module in the coupled model.Empirical studies that we have carried out demonstrate that our online coupling module can dramatically improve the parallel performance of the coupled model.The online coupling module outperforms the I/O file coupling module.When processes increase to 96,the whole process of EXP-C takes only 695.8 seconds,which is only 58.8%of the execution time of EXP-F.Based on our experiments under 2D Parallel Decomposition(2DPD),we suggest setting parallel decomposition strategies automatically to component models in order to achieve high parallel efficiency.

Phase shift effects of radio-frequency bias on ion energy distribution in continuous wave and pulse modulated inductively coupled plasmas

A retarding field energy analyzer（RFEA） is used to measure the time-averaged ion energy distributions（IEDs） on the substrate in both continuous wave（CW） and synchronous pulse modulated radio-frequency（RF） inductively coupled Ar plasmas（ICPs）.The effects of the phase shift θ between the RF bias voltage and the RF source on the IED is investigated under various discharge conditions.It is found that as θ increases from 0 to π,the IED moves towards the low-energy side,and its energy width becomes narrower.In order to figure out the physical mechanism,the voltage waveforms on the substrate are also measured.The results show that as θ increases from 0 to π,the amplitude of the voltage waveform decreases and,meanwhile,the average sheath potential decreases as well.Specifically,the potential drop in the sheath on the substrate exhibits a maximum value at the same phase（i.e.,θ = 0） and a minimum value at the opposite phase（i.e.,θ = π）.Therefore,when ions traverse across the sheath region above the substrate,they obtain less energies at lower sheath potential drop,leading to lower ion energy.Besides,as θ increases from π to 2π,the IEDs and their energy widths change reversely.

Novel exact solutions of coupled nonlinear Schro¨dinger equations with time–space modulation

We construct various novel exact solutions of two coupled dynamical nonlinear Schrōdinger equations. Based on the similarity transformation, we reduce the coupled nonlinear Schrōdinger equations with time-and space-dependent potentials, nonlinearities, and gain or loss to the coupled dynamical nonlinear Schrrdinger equations. Some special types of non-travelling wave solutions, such as periodic, resonant, and quasiperiodically oscillating solitons, are used to exhibit the wave propagations by choosing some arbitrary functions. Our results show that the number of the localized wave of one component is always twice that of the other one. In addition, the stability analysis of the solutions is discussed numerically.

Functionally diverse ligands modulate different activation states of the formyl peptide receptor 2,a G protein-coupled receptor

OBJECTIVE To identify the mechanisms by which the formyl peptide receptor 2(FPR2)mediates both inflammatory and anti-inflammatory signaling in an agonist-dependent manner.METHODS Cells expressing FPR2 were incubated with weak agonists,Aβ42 and Ac2-26,before stimulation with a strong agonist,WKYMVm.Calcium mobilization,c AMP inhibition and MAP kinase activation were measured.Intramolecular FRET were determined using FPR2 constructs with an ECFP attached to the C-terminus and a Fl As H binding motif embedded in the first or third intracellular loop(IL1 or IL3,respectively).RESULTS Aβ42 did not induce significant Ca^(2+) mobilization,but positively modulated WKYMVm-induced Ca^(2+) mobilization and c AMP reduction in a dose-variable manner within a narrow range of ligand concentrations.Treating FPR2-expressing cells with Ac2-26,a peptide with anti-inflammatory activity,negatively modulated WKYMVm-induced Ca^(2+) mobilization and c AMP reduction.Intramolecular FRET assay showed that stimulation of the receptor constructs with Aβ42 brought the C-terminal domain closer to IL1 but away from IL3.An opposite conformational change was induced by Ac2-26.The FPR2 conformation induced by Aβ42 corresponded to enhanced ERK phosphorylation and attenuated p38 MAPK phosphorylation,whereas Ac2-26 induced FPR2 conformational change corresponding to elevated p38 MAPK phosphorylation and reduced ERK phosphorylation.CONCLUSION Aβ42 and Ac2-26 induce different conformational changes in FPR2.These findings provide a structural basis for FPR2 mediation of inflammatory vs anti-inflammatory functions and identify a type of receptor modulation that differs from the classic positive and negative allosteric modulation.

基于荷电状态一致性的电池组双层动态均衡方法

针对储能系统中电池组充放电过程中能量利用率以及系统运行安全性较低的问题,提出考虑SOC一致性的电池组双层动态均衡方法。首先,采用耦合电感与Flyback变换器搭建均衡系统双层架构,建立电池组端电压、均衡电流及占空比间的关联特性。为提高电池组的供能可靠性,系统引入故障切除功能,通过改变开关阵列导通状态实现故障电池组的快速切除;其次,考虑增补电池组剩余容量较大问题,利用传统最值法改进的双层极值法,以荷电状态(stage of charge,SOC)作为均衡目标变量,对增补电池组进行快速放电均衡;最后,设计充放电及静置均衡实验,对比传统最值法,分析常态及故障切除后电路的均衡速度与均衡效率。结果表明,提出的双层均衡方法可以将均衡速度提升约10%,且故障切除后电路的均衡效率最高可达95%以上。

基于流固耦合的单轴跟踪式光伏结构风致扭转研究

以某跟踪式光伏发电系统为研究对象,通过编写自定义程序代码UDF对Fluent进行二次开发,建立单轴跟踪式光伏结构的二维模型,研究其在风荷载作用下的扭转振动问题。研究结果表明:风速达到某一特值后,结构出现等幅周期性振动,发生软颤振现象,而其阻尼比对抑制扭转振动有一定的作用,这同实际情况较吻合;光伏组件倾角在0°~20°范围内时,倾角越大,扭转振动的临界风速越低。

铌酸锂M-Z电光强度调制器光辐射模研究

铌酸锂马赫-曾德尔(M-Z)电光强度调制器光辐射模与光纤耦合是导致芯片与光纤组件耦合失效的主要原因。采用光纤与芯片高精度耦合扫描法对光波导和光辐射模进行扫描,研究了光辐射模中心位置分布、光辐射模输出光功率随偏置电压的变化特性,以及光辐射模、光波导与光纤耦合光能量的分布特性。测得光波导在X,Y方向的有效耦合范围分别为14~15.5μm和14~16μm,光辐射模在X,Y方向的有效耦合范围分别为89~92μm和92~96μm。根据所研究的光辐射模特性,制定了失效耦合的解决方案,解决了光辐射模耦合失效问题。

高频纳秒脉冲调制器的分立磁耦合驱动器设计

随着高压纳秒固态脉冲发生器在生物、工业和环境等领域的应用日益广泛和深入,脉冲波形、电压幅值、脉冲持续时间、脉冲重复频率等参数已成为特定脉冲功率应用所需的基本可控变量。为了进一步减小电源的体积、降低成本,提出一款以正极性Marx为主电路、多个脉冲变压器为核心驱动器、具有纳秒级前沿高重复频率的高压纳秒脉冲调制器。提出的驱动器结构紧凑,无需提供多路隔离供电的驱动电源,可以在高重复频率下实现两个金属氧化物半导体场效应晶体管(MOSFETs)的栅极电压快速同步上升和下降,获得百纳秒以内、幅值可控的栅极驱动电压。不仅最大脉宽不受磁芯饱和的限制,而且负偏置电压使开关管可控关断,同时在一定程度上避免了电流流过MOSFET米勒电容而引起的寄生导通,提高了电路工作的可靠性。此外,研究了不同匝数和磁芯材料对驱动波形的影响。搭建了一台14级脉冲调制器样机,测试结果表明,基于该驱动器下的调制器输出电压和脉宽都连续可调,具有改变脉冲轮廓的能力,最大输出电压可达5.5 kV,脉宽调节范围为100 ns~50 ms,最小上升时间约18 ns,重复频率为100 kHz。

基于三级式可扩展多模块并联架构的低压大电流高距径比无线电能传输系统

在低压大电流高距径比磁谐振式无线供电场合,由于传输线圈间的耦合系数很小,因此功率器件和谐振元件的电流很大,导致系统损耗大,难以优化设计。为此,文中提出一种三级式可扩展多模块并联无线电能传输系统架构,利用基波分析法对双模块并联系统建模并分析其传输特性。为提升系统效率,对比3种输出级结构及其控制策略并遴选出一种最优拓扑。进一步地,提出线圈级具体参数设计方法以减小电压电流应力并实现输入级软开关。最后搭建一台距径比为1(30 cm/30 cm)的1 kW原理样机验证理论分析,对比3种不同输出级拓扑的性能。实验结果表明,系统最高效率可达75.2%。

An Innovative Finite Element Geometric Modeling of Single-Layer Multi-Bead WAAMed Part

Finite element (FE) coupled thermal-mechanical analysis is widely used to predict the deformation and residualstress of wire arc additive manufacturing (WAAM) parts. In this study, an innovative single-layermulti-bead profilegeometric modeling method through the isosceles trapezoid function is proposed to build the FE model of theWAAMprocess. Firstly, a straight-line model for overlapping beads based on the parabola function was establishedto calculate the optimal center distance. Then, the isosceles trapezoid-based profile was employed to replace theparabola profiles of the parabola-based overlapping model to establish an innovative isosceles trapezoid-basedmulti-bead overlapping geometric model. The rationality of the isosceles trapezoid-based overlapping model wasconfirmed by comparing the geometric deviation and the heat dissipation performance index of the two overlappingmodels. In addition, the FE-coupled thermal-mechanical analysis, as well as a comparative experiment of thesingle-layer eight-bead deposition process show that the simulation results of the above two models agree with theexperimental results. At the same time, the proposed isosceles trapezoid-based overlappingmodels are all straightlineprofiles, which can be divided into high-quality FE elements. It can improve the modeling efficiency andshorten the simulation calculation time. The innovative modeling method proposed in this study can provide anefficient and high-precision geometricmodelingmethod forWAAMpart FE coupled thermal-mechanical analysis.

基于多模块分层组合模型的CAE软件耦合方法

为了弥补复杂装备CAE软件缺乏开放式、可组合式系统架构的短板,提出了一种基于多模块分层组合模型的全链路CAE软件耦合方法。首先,基于离散事件系统规范(DEVS)中离散事件模型+有限状态机+连续时间模型的组合模式,构建CAE软件前处理、数值求解、后处理阶段的核心构件库。其次,采用多模块分层分级的组合模型,基于多智能体系统的事件触发驱动机制,实现全链路CAE核心软构件的自动化耦合。面向盾构/高铁应用场景的仿真结果表明,将CAE全生命周期链路进行构件化细分、自动化耦合,利于研究多因素耦合作用下的复杂装备产品设计。此外,多模块组合模型的架构支持CAE软件核心模块的灵活组合与独立部署,实现对CAE软件向云服务平台整合的支持。