CFETR极向场磁体馈线系统线圈终端盒初步设计与分析

介绍了中国聚变工程实验堆(CFETR)极向场线圈馈线系统终端盒(CTB)设计,CTB由外盒体、80K内冷屏、电流引线及超导母线、内部管路系统、阀门系统等子部件组成.利用ANSYS有限元软件,在运行工况和地震工况下对CTB外盒体及内冷屏进行结构强度校核、结构热分析和地震响应分析,得到CTB外盒体的位移、应力分布云图和在地...     

W波段电光相位调制器的设计与建模分析

W波段(2.73～4 mm)电光相位调制器(EOM)结构具有多参数和设计复杂的特点,参考共面波导传输线理论和EOM理论,结合三维电磁仿真高频结构仿真软件HFSS,对调制器进行有限元分析和计算。针对EOM几何结构中的关键参数,在4个维度上进行模型仿真计算,建立EOM的多维度数学模型。根据仿真模型,得到EOM几何结构参数与主要性能的变化规律,确立EOM的模型结构。通过结构优化,得到频率为100 GHz的EOM模型,调制器速率匹配,阻抗匹配,并且衰减较小。     

ITER装置CTB盒体冷屏结构设计与传热性能的数值模拟

为了满足ITER国际组对CTB盒体冷屏的技术要求,论文对其结构型式和传热性能分别进行了设计、选型和数值模拟分析。通过对设计后的冷屏结构进行ANSYS分析,选择了冷屏为3mm厚的3003铝合金材料,确定了冷却管为22mm×22mm-φ18mm外方内圆截面的结构型式,并选择由卡子实现冷却管与冷屏面板的连接固定。最后,利用FLUENT软件针对设计后的冷屏结构进行了流固耦合数值模拟分析,获取了冷屏面板上总体温度的分布情况,验证了论文中选取和设计的冷屏结构型式能够满足ITER国际组设计技术要求,为下一步CTB盒的设计研制提供了技术保证和依据。     

体声波双工器中滤波器的参数化设计方法

Tx与Rx滤波器,作为体声波(BAW)双工器的关键部件,其中各薄膜体声波谐振器(FBAR)单元的谐振区面积会影响滤波器的插入损耗和带外抑制这两个重要指标。由于这两个指标是相互制约的,在设计时往往需要折衷考虑,这使得各FBAR单元的谐振区面积设计成为BAW双工器设计的难点之一。为了解决这一问题,提出了一种Tx与Rx滤波器的参数化设计方法。在ADS软件中以FBAR的Mason模型为基础构建了梯形拓扑结构的滤波器电路模型。设置其中各串联FBAR的谐振区面积值以及串并联FBAR的谐振区面积比值为两类优化参数。以给定的滤波器插入损耗与带外抑制为优化目标,使用ADS软件中基于梯度的优化算法得到各参数的优化值。根据优化结果可以简单地计算得到滤波器中各FBAR单元的谐振区面积。以一个工作在LTE band 7的BAW双工器为设计案例展示了该方法的应用流程。设计结果的仿真验证表明:Tx滤波器的插损小于2dB、在Rx滤波器通带内的抑制大于40dB;Rx滤波器的插损小于1.9dB、在Tx滤波器通带内的抑制大于40dB;满足BAW双工器中Tx与Rx滤波器的性能指标。由此验证了该方法的可行性和易用性。     

EAST托卡马克装置外冷屏的热负荷分析

外真空杜瓦冷屏 (简称外冷屏 )是 EAST超导托卡马克核聚变装置的重要部件之一 ,它在处于室温下的外真空杜瓦与运行在 4 .5 K温度下的超导线圈之间形成了一道隔热的屏障 ,以保证装置能够稳定高效的运行。文中运用有限元分析软件 ANSYS对外冷屏封头、中筒、底座的传热情况做了计算与分析 ,以得到在氦气入口处压强为 5 .2 bar,温度为 80 K的情况下 ,外冷屏低温面板的详细设计方案     

多晶硅TFT有源OLED两管像素电路的研究

在采用精确的模型基础上,利用AIM-Spice软件对有源OLED poly-Si薄膜晶体管(TFT)驱动电路和1×4矩阵电路进行分析研究。最后得到合理的电路参数,使OLED能够达到一定的显示亮度要求。在每帧时间内维持电流恒定,并且在时变的灰度信号作用下能够良好地跟踪响应,最大程度上消除了TFT的一些非线性特性对OLED驱动电流的影响。为OLED显示器像素驱动电路的设计、参数选取、性能分析等提供依据。     

红外探测器冷屏设计

分析了不同F数下的冷屏高度与焦平面响应率非均匀性的关系,在冷屏高度增加的不同阶段,不同F数的冷屏通光孔径带来的杂散辐射影响不同,焦平面均匀性出现增加、减小或不变等情况,在保证焦平面最大响应梯度不超过25%以及冷屏最大温差不超过5 K的情况下,通过曲线确定冷屏高度。同时基于点源透过率（PST）的仿真结果,对4种外观结构的冷屏分别在F1.2～F5.5下的杂散光抑制效果进行分析,进一步得到每种冷屏结构在不同F数下的适用情况。提出3种冷屏排气孔结构优化方案,优化后的排气孔结构焦平面接收的探测器内部热辐射功率较优化前减小了约87%。     

空间光学遥感器次镜参数化设计

根据某空间遥感器次镜设计指标要求,采用ANASYS多参数优化设计功能对次镜轻量化进行优化设计。利用UG软件建立反射镜体结构的参数化模型,在ANSYS中将有关结构参数变量指定为优化设计变量,以反射镜体在地面重力作用下的镜面变形误差以及反射镜支撑孔位移为零作为约束条件,结合有限元法对镜体轻量化结构的尺寸参数进行优化分析,得到了轻量化率达到80.635%,镜面面形精度RMS为6.953 nm,PV值为31.317 nm,满足设计要求的反射镜。     

运载火箭多学科概念设计软件构建技术研究

为了满足新型运载火箭“通用化、组合化、系列化”的设计要求,同时朝着降本增效的方向发展,需要研究多专业一体化设计方法。通过梳理概念设计时总体、气动、弹道、姿控各专业的工程算法,结合MDO理论与层次式模型管理的软件架构方法,提出了面向运载火箭概念设计的多学科集成优化软件构建技术,包括专业模型、CAD模型、仿真模型、优化模型、迭代模型等在内的8类软件模型的定义与有效管理,并形成专业计算与分析软件。此软件可实现火箭芯级、助推器、稳定翼面等总体外形的参数化设计,三维图像的展示与编辑,基于部件组合法的气动工程计算与性能分析,质量特性计算,动力系统选型及弹道计算与分析,优化设计等功能。通过此软件构建技术的研究与功能实现,为运载火箭概念设计过程的多学科集成优化设计提供了工具支撑。     

长条形反射镜体轻量化结构的参数优化设计

提出了一种对长条形反射镜轻量化结构进行优化设计的方法。利用ANSYS软件建立反射镜体结构的参数化模型,将有关结构参数变量指定为优化设计变量,以反射镜体在地面重力作用下的镜面变形误差以及在承受发射过载时所产生的最大VonMises应力作为约束条件,结合有限元法对镜体轻量化结构的尺寸参数进行优化分析,得到了轻量化程度高,镜面变形误差完全满足设计要求的反射镜体。     

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In the integrated design framework provided in the CFETR integration design platform (CIDP), a workflow that can efficiently optimize the design of the vacuum vessel thermal shield (VVTS) was developed based on the parametric model. In the workflow, according to the geometry parameters of the parametric model of the VVTS, automatic modeling and finite element analysis in CAD/CAE software like CATIA and ANSYS can be driven by OPTIMUS software. The response surface model and sensitivity analysis are then used to determine the parameters which are closely related to the objective optimization. The optimized design parameters of the VVTS, which satisfy the design criterion, can be obtained by further optimization workflow. The application of the workflow is demonstrated by an example, where the safety requirement during plasma disruption events is considered. While the stress obtained by electromagnetic- structural analysis can meet the design criteria, the mass of the VVTS is minimized to reduce the construction cost and improve economics.     

CFETR内冷屏结构方案初探

基于现有冷屏结构,结合CFETR聚变堆装置的结构特点,提出了一种沿冷却板厚度方向钻冷却通道的深孔结构方案.对内冷屏各部件设计了并联加串联的特殊流道,采用有限元法计算了该方案内冷屏各部件的温度分布.结果表明,采用深孔法冷却方式,冷屏温度分布更均匀,降温效果更好.在输出辐射功率相近的条件下,深孔法的冷却方式可将表面辐射率上...     

Optimum connecting dampers to reduce the seismic responses of parallel structures

Parameters of connecting dampers between two adjacent structures and twin-tower structure with large podium are optimized through theoretical analysis. The connecting visco-elastic damper (VED) is represented by the Kelvin model and the connecting viscous fluid damper (VFD) is represented by the Maxwell model. Two optimization criteria are selected to minimize the vibration energy of the primary structure and to minimize the vibration energy of both structures. Two representative numerical examples of adjacent structures and one three-dimensional finite element model of a twin-tower with podium structure are used to verify the correctness of the theoretical approach. On the one hand, by means of theoretical analysis, the first natural circular frequencies and total mass of the two structures can be taken as parameters in the general formula to get the optimal parameters of the coupling dampers. On the other hand, using the Kanai-Tajimi filtered white-noise ground motion model and several actual earthquake records, the appropriate parameters of two types of linking dampers are obtained through extensive parametric studies. By comparison, it can be found that the results of parametric studies are consistent with the results of theoretical studies for the two types of dampers under the two optimization criteria. The effectiveness of VED and VFD is investigated in terms of the seismic response reduction of the neighboring structures. The numerical results demonstrate that the seismic response and vibration energy of parallel structures are mitigated significantly. The performances of VED and VFD are comparable to one another. The explicit formula of VED and VFD can help engineers in application of coupled structure control strategies.     

The Design of Potter Horns for THz Applications Using a Genetic Algorithm

We describe the design and performance of Potter horns at millimetre and submillimetre wavelength employing a novel software package that we have developed, using Genetic Algorithm. The horn is easy to fabricate and exhibits excellent beam circularity and low cross polarization over a 15% bandwidth which is sufficient for many applications. Excitation of the required higher order modes is done by either a step or a flare discontinuity at the horn throat. In each case we provide design curves that give the optimum parameters of the horn geometry as a function of frequency and beamwidth. The range of values provided covers the parameters required for the design of horns for telescope feeds and various other instruments. The design curves show clearly that the flare-step performance is superior to the traditional groove-step Potter horn. The simulations for designing these horns were carried out at millimetre and submillimetre wavelengths but the results can be scaled to lower or higher frequencies. A key component in the design method is the optimization software that searches for the correct magnitude and location of the flare discontinuities. We have developed a software package based on the combination of modal matching, a genetic algorithm (GA) and downhill simplex optimization. The genetic code is first used to locate the proximity of the global minimum. The set of parameters obtained are then used as a starting point for the simplex method, which refines the parameters to the required accuracy.     

Brake squeal reduction of vehicle disc brake system with interval parameters by uncertain optimization

An uncertain optimization method for brake squeal reduction of vehicle disc brake system with interval parameters is presented in this paper. In the proposed method, the parameters of frictional coefficient, material properties and the thicknesses of wearing components are treated as uncertain parameters, which are described as interval variables. Attention is focused on the stability analysis of a brake system in squeal, and the stability of brake system is investigated via the complex eigenvalue analysis (CEA) method. The dominant unstable mode is extracted by performing CEA based on a linear finite element (FE) model, and the negative damping ratio corresponding to the dominant unstable mode is selected as the indicator of instability. The response surface method (RSM) is applied to approximate the implicit relationship between the unstable mode and the system parameters. A reliability-based optimization model for improving the stability of the vehicle disc brake system with interval parameters is constructed based on RSM, interval analysis and reliability analysis. The Genetic Algorithm is used to get the optimal values of design parameters from the optimization model. The stability analysis and optimization of a disc brake system are carried out, and the results show that brake squeal propensity can be reduced by using stiffer back plates. The proposed approach can be used to improve the stability of the vehicle disc brake system with uncertain parameters effectively.     

Shape and topology optimization for electrothermomechanical microactuators using level set methods

In this short note, a shape and topology optimization method is presented for multiphysics actuators including geometrically nonlinear modeling based on an implicit free boundary parameterization method. A level set model is established to describe structural design boundary by embedding it into the zero level set of a higher-dimensional level set function. The compactly supported radial basis functions (CSRBF) are introduced to parameterize the implicit level set surface with a high level of accuracy and smoothness. The original more difficult shape and topology optimization driven by the Hamilton–Jacobi partial differential equation (PDE) is transferred into a relatively easier parametric (size) optimization, to which many well-founded optimization algorithms can be applied. Thus the structural optimization is transformed to a numerical process that describes the design as a sequence of motions of the design boundaries by updating the expansion coefficients of the size optimization. Two widely studied examples are chosen to demonstrate the effectiveness of the proposed method.     

A chemical kinetic model for chemical vapor deposition of carbon nanotubes

Carbon nanotubes (CNTs) are classified among the most promising novel materials due to their exceptional physical properties. Still, optimal fabrication of carbon nanotubes involves a number of challenges. Whatever be the fabrication method, a process optimization can be evolved only on the basis of a good theoretical model to predict the parametric influences on the final product. The work reported here investigates the dependence of the deposition parameters on the controllable parameters for carbon nanotube growth during Chemical vapor deposition (CVD), through a chemical kinetic model. The theoretical model consisted of the design equations and the energy balance equations, based on the reaction kinetics, for the plug flow and the batch reactor, which simulate the CVD system. The numerical simulation code was developed in-house in a g++ environment. The results predicted the growth conditions for CNT: the deposition temperature, pressure and number of atoms, which were found to be influenced substantially by the initial controllable parameters namely the temperature, volumetric flow rate of the carbon precursor, and the reaction time. An experimental study was also conducted on a CVD system developed in the laboratory, to benchmark the computational results. The experimental results were found to agree well with the theoretical predictions obtained from the model.     

Optimization of Circular Ring Microstrip Antenna Using Genetic Algorithm

Circular ring microstrip antennas have several interesting properties that make it attractive in wireless applications. Although several analysis techniques such as cavity model, generalized transmission line model, Fourier-Hankel transform domain and the method of matched asymptotic expansion have been studied by researchers, there is no efficient design tool that has been incorporated with a suitable optimization algorithm. In this paper, the cavity model analysis along with the genetic optimization algorithm is presented for the design of circular ring microstrip antennas. The method studied here is based on the well-known cavity model and the optimization of the dimensions and feed point location of the circular ring antenna is performed via the genetic optimization algorithm, to achieve an acceptable antenna operation around a desired resonance frequency. The antennas designed by this efficient design procedure were realized experimentally, and the results are compared. In addition, these results are also compared to the results obtained by the commercial electromagnetic simulation tool, the FEM based software, HFSS by ANSOFT.     

Nonlinear performances of dual-pump amplifiers in silicon waveguides

The performances of a dual-pump parametric and Raman amplification process and the wavelength conversion in silicon waveguides are investigated. By setting the Raman contribution fraction f to be 0.043 in our analytical model, the amplification gain of the probe signal can be obtained to be over 10 dB. The pump transfer noise (PTN), the quantum noise (QN), and the total noise figure (TNF) are discussed, and the TNF has a constant value of about 4 dB in the gain bandwidth. An idler signal generated during the parametric amplification (PA) process can be used to realize the wavelength conversion in wavelength division multiplexing (WDM) systems. In addition, the pump signal parameters, the generated free carrier lifetime and effective mode area (EMA) of the waveguide are analysed for the optimization of signal gain and noise characteristics.