稀土铝合金电缆导体退火过程理论模型的研究

根据罐式退火炉退火过程的传热特点,分析稀土铝合金电缆导体退火过程各阶段炉膛内传热形式,建立铝合金电缆导体导热的数学模型.     

电磁线绝缘在线检测仪的设计与研究

绝缘测试是电磁线质量检测的一项重要内容,为了准确可靠的实现电磁线绝缘的在线检测,提出了基于CPLD数字电路的设计方案,给出了其软、硬件设计。系统选择半桥电路加空心脉冲变压器设计对绝缘层的高压放电电路,可输出500到10000V的可调交流电。系统通过检测电磁线漏电流实现对电磁线绝缘测试。实验结果表明,系统满足多种电磁线的绝缘测试要求。     

Design of electromagnetic coil launcher interior ballistic projectile velocity measurement system

为了实现对电磁线圈发射器内弹道弹速的测量,克服常规武器内弹道弹速测试方法的不足,采用光电传感器和现场可编程门阵列(FPGA)技术开发电磁线圈发射器内弹道弹速测量系统.NiosⅡ软核微处理器作为测量系统下位机,根据上位机命令协调控制多级测速节点运行.系统通过对多段微小行程平均速度的测定求得内弹道弹速信息.实际测试结果表明:该系统能够准确测量电磁线圈发射器内弹道弹丸运行速度,具有较高的测量精度,对电磁发射试验环境具有较强的适应性,体积小,可靠性高,满足测量系统设计要求.     

基于虚拟温度法的间歇过程换热器网络综合

提出了基于时间段模型(TSM)综合间歇过程换热器网络的方法,用虚拟温度法代替传统的单一最小传热温差,将各流股的温差贡献值作为决策变量,年度总费用最小作为目标函数建立数学模型.应用遗传膜拟退火算法对上述数学模型进行求解,分别获得每个时间间隔内的子换热器网络结构,并进一步对总换热器网络做结构优化,使其既满足流股的换热要求,又满足年费用最小.方法应用于实例计算,结果比基于最小传热温差获得的换热器网络年度总费用节省6.0%,换热器减少5台,说明这种方法既节省费用,又简化了网络结构.     

涡流冷壁推力室传热模型分析计算

研究发动机燃烧室温度优化控制问题,由于燃烧室温度控制较难,为了预估新型涡流燃烧冷壁火箭发动机的壁面温度,根据发动机内部流动和传热分析,对组合化学平衡、辐射传热和热传导特性,提出了一维传热模型.采用模型对以氢氧为推进剂的涡流燃烧室进行了传热过程和影响因素的仿真分析,获得了稳定状态下的壁面温度,以及燃烧室压力、氧化剂喷注速度、燃烧室长度等参数对壁温的影响关系,仿真结果与实验一致.证明模型为涡流燃烧发动机设计提供了重要工具,对进一步的实验研究有指导意义.     

罩式退火炉模型辨识及节能控制

本文以罩式退火炉为对象,根据其退火过程的输入输出数据,用系统辨识的方法,建立了 线性动态模型.在此基础上,根据最佳控制理论,导出了节能控制规律--开关控制.结合 对象的传热特点,用峰值预极的方法解决了开关状态的选择问题.计算机仿真结果表明,采用 上述方法控制,节能效果在5%以上.     

基于MPI的结晶器传热并行计算方法

针对连铸结晶器传热数值模拟计算量较大、耗时长的特点,基于自行构建的并行计算环境,对计算数据域采用对等模式划分成块,设计了用于结晶器传热数值模拟的并行计算方法.测试结果表明,采用并行算法可获得与串行算法相同的模拟结果,在同等计算量下极大地减少了计算时间,提高了数值模拟的效率.为有效提升传热计算速度和更为复杂条件下的结晶器数值模拟提供了可行途径.     

载重子午线轮胎滚动阻力有限元仿真分析

研究汽车轮胎低滚动阻力优化设计,针对轮胎滚动阻力引起的温度对材料性能影响难以测定的问题,根据车辆的轮胎温度与材料性能有关,建立了含热力学耦合的滚动阻力分析模型.要求模型包含三个部分:结构分析、传热分析和滚动阻力计算.与传统模型相比,增加了传热分析部分,利用传热分析计算结果更新材料参数,解决了以往在滚动阻力仿真时不考虑温度影响的问题.对模型进行仿真分析,通过滚动阻力试验验证改进的模型具有更高的精度,可以为低滚动阻力轮胎结构设计与优化提供指导.     

CAE在强化传热节能减排中的应用

为解决管壳式换热器传热效率低下的问题,以最典型的列管式换热器为研究对象,建立换热管内置转子组合式强化传热装置的三维模型,模拟换热管内流场、温度场、压力场以及换热过程,得到管内流体的流动规律和传热性能的计算结果. 模拟计算结果显示,内置转子组合式强化传热装置的换热管内尤其是近壁区域有较强的湍流度;转子与管壁之间缝隙内的流体有明显的螺旋环绕流动,可显著提高传热系数,并具有自清洁作用. 研究表明,利用CAE手段解决热交换过程的瓶颈问题,可大幅度提高能源利用效率,为实现节能减排的战略目标作出贡献.     

约束优化问题的改进遗传算法设计

遗传算子是影响遗传算法优化效果的重要因素,针对目前遗传算法研究中对约束优化问题求解的不足,提出基于退火思想的退火选择算子和加权适应度算子,并给出了退火选择算子和加权适应度算子设计方法及其计算过程.在此基础上与现有的遗传算子结合,提出一种新的改进遗传算法,分析了改进遗传算法与基于罚函数遗传算法之间在原理上的区别.最后以两个测试函数为算例对算法进行了性能测试,结果表明改进的遗传算法具有良好的优化性能,能获得更好的优化结果.     

Computer simulation of the temperature and electromagnetic field in an inductively heated semiconductor

The electromagnetic and temperature fields in an inductively heated semiconductor interact with each other in a sophisticated way through the heat dependence of the material parameters and the heat source density determined by the eddy currents. The paper deals with a computer analysis of the interacting fields taking into account the nonlinear temperature dependence of the material parameters. The basic electromagnetic and heat conduction equations are discussed, and a transformation will be introduced for the calculation of the electromagnetic field outside the material. The nonlinear equation system resulting from discretization is solved by an iterative method, whose relaxation factor is optimized during the iteration. Experiences gained in the course of the numerical calculations are reported, and results of a calculation performed with specific physical data are described.     

热泡式喷墨的建模与分析

喷墨过程的数值建模是建立在一维热传导公式，温度-压强关系式和能量、物质转换关系的平衡的基础上的。一维热传导公式用来考虑气泡和它周围液体之间的能量交换以及气-液交界层的温度分布。温度-压强关系式和能量转换关系用来考虑气泡的增长和破裂过程。气泡产生的初始温度、初始压强以及控制电压等参数都在本模型中进行分析，分析的结果为设计喷墨打印机提供了最基础的资料。     

热泡式喷墨的建模与分析

喷墨过程的数值建模是建立在一维热传导公式,温度—压强关系式和能量、物质转换关系的平衡的基础上的。一维热传导公式用来考虑气泡和它周围液体之间的能量交换以及气—液交界层的温度分布。温度—压强关系式和能量转换关系用来考虑气泡的增长和破裂过程。气泡产生的初始温度、初始压强以及控制电压等参数都在本模型中进行分析,分析的结果为设计喷墨打印机提供了最基础的资料。     

Isoparametric line and transition finite elements with temperature and temperature gradients as primary variables for two dimensional heat conduction

This paper presents isoparametric line and transition finite element formulation for two dimensional heat conduction. The element properties are derived using weak formulation of the Fourier heat conduction equation and the element approximation where nodal temperatures and the nodal temperature gradients are retained as primary variables. The formulation permits linear temperature distribution through the element thickness. Distributed heat flux as well as convective boundaries are permitted on all four faces of the elements. Furthermore, the elements can have internal heat generation as well as orthotropic material properties. The superiority of the formulation in terms of efficiency and accuracy is demonstrated. Numerical examples are presented to illustrate their applications, and a comparison is made with theoretical results.     

Visual simulation of heat shimmering and mirage

We provide a physically-based framework for simulating the natural phenomena related to heat interaction between objects and the surrounding air. We introduce a heat transfer model between the heat source objects and the ambient flow environment, which includes conduction, convection, and radiation. The heat distribution of the objects is represented by a novel temperature texture. We simulate the thermal flow dynamics that models the air flow interacting with the heat by a hybrid thermal lattice Boltzmann model (HTLBM). The computational approach couples a multiple-relaxation-time LBM (MRTLBM) with a finite difference discretization of a standard advection-diffusion equation for temperature. In heat shimmering and mirage, the changes in the index of refraction of the surrounding air are attributed to temperature variation. A nonlinear ray tracing method is used for rendering. Interactive performance is achieved by accelerating the computation of both the MRTLBM and the heat transfer, as well as the rendering on contemporary graphics hardware (GPU)     

台车式退火炉自动控制系统

以精轧台车式退火炉过程的自动控制系统设计为背景,在采用国外先进集散控制系统的结构的基础上,针对退火质量和温度控制问题,一方面通过采用脉冲燃烧方案提高燃烧效率和温场的均匀性;另一方面,针对不同的退火阶段,分别从热平衡方程进行分析,进而设计了以热平衡方程为核心的前馈模型,结合PID算法有效提高了温度控制的精度。实际应用结果证明:该控制系统炉温控制精度高,钢坯横纵向温差较小,大大提高了退火质量。     

Anti-diffusive methods for hyperbolic heat transfer

The hyperbolic heat transfer equation is a model used to replace the Fourier heat conduction for heat transfer of extremely short time duration or at very low temperature. Unlike the Fourier heat conduction, in which heat energy is transferred by diffusion, thermal energy is transferred as wave propagation at a finite speed in the hyperbolic heat transfer model. Therefore methods accurate for Fourier heat conduction may not be suitable for hyperbolic heat transfer. In this paper, we present two anti-diffusive methods, a second-order TVD-based scheme and a fifth-order WENO-based scheme, to solve the hyperbolic heat transfer equation and extend them to two-dimension, including a nonlinear application caused by temperature-dependent thermal conductivity. Several numerical examples are applied to validate the methods. The current solution is compared in one-dimension with the analytical one as well as the one obtained from a high-resolution TVD scheme. Numerical results indicate that the fifth-order anti-diffusive method is more accurate than the high-resolution TVD scheme and the second-order anti-diffusive method in solving the hyperbolic heat transfer equation.     

Multi-time-scale heat transfer modeling of turbid tissues exposed to short-pulsed irradiations

A combined hyperbolic radiation and conduction heat transfer model is developed to simulate multi-time-scale heat transfer in turbid tissues exposed to short-pulsed irradiations. An initial temperature response of a tissue to an ultrashort pulse irradiation is analyzed by the volume-average method in combination with the transient discrete ordinates method for modeling the ultrafast radiation heat transfer. This response is found to reach pseudo steady state within 1 ns for the considered tissues. The single pulse result is then utilized to obtain the temperature response to pulse train irradiation at the microsecond/millisecond time scales. After that, the temperature field is predicted by the hyperbolic heat conduction model which is solved by the MacCormack's scheme with error terms correction. Finally, the hyperbolic conduction is compared with the traditional parabolic heat diffusion model. It is found that the maximum local temperatures are larger in the hyperbolic prediction than the parabolic prediction. In the modeled dermis tissue, a 7% non-dimensional temperature increase is found. After about 10 thermal relaxation times, thermal waves fade away and the predictions between the hyperbolic and parabolic models are consistent.     

Kinetic model of radiation-induced gas conductivity

A kinetic equation for low-energy electrons induced in gas by ionizing radiation is studied. The kinetic equation takes into account elastic, inelastic, and ionization collisions between electrons and gas molecules, as well as the interaction with an external electric field. The process of the conduction current generation is considered. A small parameter is calculated as a ratio of the energy accumulated by an electron between collisions to the thermal energy. An approximate solution is constructed of the kinetic equation for electron concentration and flow. The study resulted in obtaining quadrature formulas for the calculation of electron conduction of an ionized gas in the model of a radiation-induced electromagnetic field.     

能量传导模型及在医学图像分割中的应用

提出了一种基于水平集框架的能量传导模型ECM(energy conduction model)用于对医学图像进行分割.该模型通过对图像中的灰度分布和空间中的温度场分布进行对比,有效定义了图像能量和图像能量的传导方程,并通过模拟热量传递的过程对方程进行求解.ECM模型的优点在于,它在描述图像灰度分布的全局特征的同时,有效地捕捉到图像局部区域的灰度对比度变化,因此它能够对灰度分布不均匀和含有噪声的图像进行精确分割.基于水平集函数本身的拓扑可变性,该方法还能够实现同一图像中的多目标分割.使用该方法对模拟和真实的医学图像进行了分割实验,实验结果表明了该方法的有效性和可靠性.