Mathematical Model for Temperature Field of Strip Coil in Cooling and Heating Process

The convection between the strip coil boundary and the surrounding medium was studied, and the mathematical model and boundary conditions for the temperature field of anisotropic strip coil was proposed, and the temperature field of strip coil were calculated by the analytic method.

Model reduction for supersonic cavity flow using proper orthogonal decomposition(POD)and Galerkin projection

The reduced-order model （ROM） for the two-dimensional supersonic cavity flow based on proper orthogonal decomposition （POD） and Galerkin projection is investigated. Presently, popular ROMs in cavity flows are based on an isentropic assumption, valid only for flows at low or moderate Mach numbers. A new ROM is constructed involving primitive variables of the fully compressible Navier-Stokes （N-S） equations, which is suitable for flows at high Mach numbers. Compared with the direct numerical simulation （DNS） results, the proposed model predicts flow dynamics （e.g., dominant frequency and amplitude） accurately for supersonic cavity flows, and is robust. The comparison between the present transient flow fields and those of the DNS shows that the proposed ROM can capture self-sustained oscillations of a shear layer. In addition, the present model reduction method can be easily extended to other supersonic flows.

Analytical model of tilted driver–pickup coils for eddy current nondestructive evaluation

A driver-pickup probe possesses better sensitivity and flexibility due to individual optimization of a coil.It is fre-quently observed in an eddy current(EC)array probe.In this work,a tilted non-coaxial driver-pickup probe above a multilayered conducting plate is analytically modeled with spatial transformation for eddy current nondestructive evalua-tion.Basically,the core of the formulation is to obtain the projection of magnetic vector potential(MVP)from the driver coil onto the vector along the tilted pickup coil,which is divided into two key steps.The first step is to make a projection of MVP along the pickup coil onto a horizontal plane,and the second one is to build the relationship between the pr,ojected MVP and the MVP along the driver coil.Afterwards,an analytical model for the case of a layered plate is established with the reflection and transmission theory of electromagnetic fields.The calculated values from the resulting model indicate good agreement with those from the finite element model(FEM)and experiments,which validates the developed analytical model.

Numerical and experimental analysis of AC loss for CFETR CS model coil

The central solenoid(CS) is an important component of China Fusion Engineering Test Reactor, for producing, forming and stabilizing plasma in the superconducting tokamak. It is a complicated work to design and manufacture the large superconducting CS magnet, so it is meaningful to design a central solenoid model coil(CSMC) and analyze its electromagnetic properties in advance. In this paper, the structure, design parameters and magnetic field distribution of the CS model coil are discussed. The peak power of radial and axial turn conductors and time bucket loss are analyzed by using piecewise-linear method. The CSMC AC loss with different Nb3 Sn CICCs and AC loss of ITER CS coil are compared. The special electrometric method to measure AC loss of the CS model coil for future reference is presented.

A commutation analytical model for quench protection of the CFETR central solenoid model coil

A central solenoid model coil will be set up to develop and verify the technique for the full-size central solenoid coil of the China Fusion Engineering Test Reactor.In case of quench and failures of superconducting coils,the quench protection(QP)system,which employs fuse-based commutation technology,is designed.This paper presents an analytical model to investigate the commutation process in the QP circuit.The model consists of the QP circuit equations,the breaker arc model,the fuse pre-arc model,and the fuse arc model.The model is employed in the whole commutation process including current transfer from breaker branch to the fuse branch model,then from fuse branch to the discharge resistor branch,and current decrease to zero in the discharge resistor.The experiment result verified the effectiveness of the presented model.The model might be helpful for design of the fuse and optimization of the commutation circuit.

Numerical Application of the Flamelet Model to Supersonic Turbulent Combustion

In this study,the flow field structure inside a scramjet combustor is numerically simulated using the flamelet/progress variable model.Slope injection is considered,with fuel mixing enhanced by means of a streamwise vortex.The flow field structure and combustion characteristics are analyzed under different conditions.Attention is also paid to the identification of the mechanisms that keep combustion stable and support enhanced mixing.The overall performances of the combustion chamber are discussed.

Simple Emission Model of Supersonic Molecular Beam

Recently some modes of supersonic molecular beam injection （SMBI）have been put forward. Among them there are electrostatic “double layer”-shielding, simple collective and optimized numerical models to explain the experiment phenomenon. The penetrated depth A and particle deposition were calculated theoretically. About 1/7 in- cident thermal electron flux was amputated and, A increased seven times. The previous simulation is not enough for the SMBI fueling mechanism research. Hence, further investigations, both in experiment and in theory should be developed. The phenomena of line emission due to supersonic molecular beam （SMB） are of particular importance.

Numerical Simulation of Direct-contact Condensation from a Supersonic Steam Jet in Subcooled Water

The phenomenon of direct-contact condensation,used in steam driven jet injectors,nuclear reactor emergency core cooling systems and direct-contact heat exchangers,was investigated computationally by introducing a thermal equilibrium model for direct-contact condensation of steam in subcooled water.The condensation model presented was a two resistance model which takes care of the heat transfer process on both sides of the interface and uses a variable steam bubble diameter.The injection of supersonic steam jet in subcooled water tank was simulated using the Euler-Euler multiphase flow model of Fluent 6.3 code with the condensation model incorporated. The findings of the computational fluid dynamics（CFD） simulations were compared with the published experimental data and fairly good agreement was observed between the two,thus validating the condensation model.The results of CFD simulations for dimensionless penetration length of steam plume varies from 2.73-7.33,while the condensation heat transfer coefficient varies from 0.75-0.917 MW·（m ^2 ·K）^ -1 for water temperature in the range of 293-343 K.

Mathematic modeling on flexible cooling system in hot strip mill

A novel cooling system combining ultra fast cooling rigs with laminar cooling devices was investigated.Based on the different cooling mechanisms,a serial of mathematic models were established to describe the relationship between water flow and spraying pressure and the relationship between water spraying heat flux and layout of nozzles installed on the top and bottom cooling headers.Model parameters were validated by measured data.Heat transfer models including air convection model,heat radiation model and water cooling capacity model were detailedly introduced.In addition,effects on cooling capacity by water temperature and different valve patterns were also presented.Finally,the comparison results from UFC used or not have been provided with respect to temperature evolution and mechanical properties of Q235B steel grade with thickness of 7.8 mm.Since online application of the sophisticated CTC process control system based on these models,run-out table cooling control system has been running stably and reliably to produce resource-saving,low-cost steels with smaller grain size.

The torsion model of soft tissue in virtual surgery

In order to solve the problem of real-time soft tissue torsion simulation in virtual surgeries,a torsion model based on coil spring is proposed to actualize real-time interactions and applications in virtual surgeries. The proposed model is composed of several connected coil springs in series. The sum of torsion deformation on every coil is equivalent to the soft tissue surface deformation. The calculation of the model is simple because the method for calculating the torsion deformation for each coil spring is the same. The virtual surgery simulation system is established on PHANTOM OMNI haptic device based on the Open GL 3 D graphic interface and VC + + software,and it is used to simulate the torsion deformation of virtual legs and arms. Experimental results show that the proposed model can effectively simulate the torsion deformation of soft tissue while being of real-time performance and simplicity,which can well meet requirements of virtual operation simulations.

Spectrum Blueshifting of Ultrashort UV Laser Pulse Induced by Ionization of Supersonic He and Ar Gas Jets

The predominant spectral blueshifting of a sub-picosecond UV laser pulse induced by ultrafast ionization of noble gases was investigated. Spectral measurements were made at various gas densities. Typical quasi-periodic structures in the blueshifted spectrum were obtained. The observations were in connection with the so-called self-phase modulation of laser pulses in the ultrafast ionization process which was simply simulated with an ADK （Ammosov-Delone-Krainov） ionization model. Some quantitative information can be deduced from the measurements and calculations.

Mathematical model for cooling process and its self-learning applied in hot rolling mill

Control precision of coiling temperature is one of the key factors affecting the profile shape and surface quality during the cooling process of hot rolled steel strip.For this reason,the core of temperature control precision is to establish an effective cooling mathematical model with self-learning function.Starting from this point,a cooling mathematical model with nonlinear structural characteristics is established in this paper for the cooling process of hot rolled steel strip.By the analysis of self-learning ability,key parameters of the mathematical model could be constantly corrected so as to improve temperature control precision and adaptive capability of the model.The site actual application results proved the stable performance and high control precision of the proposed mathematical model,which would lay a solid foundation to improve the steel product qualities.

Application of Microstructure Engineering in Steel Coil Cooling Process

The coil cooling and its role in a hot strip mill were reviewed. A mathematical model was developed to describe and analyze the thermal history and its impact on precipitation phenomena during coil cooling for plain carbon, HSLA-V and HSLA-Nb steels. The predicted result of the thermal model was compared with that measured from industrial coil. The effect of cooling condition and coil dimension on the thermal history and final mechanical properties of the steel strip was examined. The coiling temperature and cooling rate have crucial influence on the precipitation strengthening.

Design of Online Vision Detection System for Stator Winding Coil

The quality of the stator winding coil directly affects the performance of the motor.A dual-camera online machine vision detection method to detect whether the coil leads and winding regions were qualified was designed.A vision detection platform was designed to capture individual winding images,and an image processing algorithm was used for image pre-processing,template matching and positioning of the coil lead area to set up a coordinate system.After eliminating image noise by Blob analysis,the improved Canny algorithm was used to detect the location of the coil lead paint stripped region,and the time was reduced by about half compared to the Canny algorithm.The coil winding region was trained with the ShuffleNet V2-YOLOv5s model for the dataset,and the detect file was converted to the Open Neural Network Exchange(ONNX)model for the detection of winding cross features with an average accuracy of 99.0%.The software interface of the detection system was designed to perform qualified discrimination tests on the workpieces,and the detection data were recorded and statistically analyzed.The results showed that the stator winding coil qualified discrimination accuracy reached 96.2%,and the average detection time of a single workpiece was about 300 ms,while YOLOv5s took less than 30 ms.

Distribution of Electromagnetic Force of Square Working Coil for High-Speed Magnetic Pulse Welding Using FEM

Magnetic pulse welding process, one of high speed welding processes, uses electromagnetic force from discharged current through a working coil which develops a repulsive force between the induced currents flowing parallel and in the opposite direction in the pipe to be welded. For achieving the successful weldment and using this process, the design of working coil is the most important factor, because working coil has to generate a high-intensity magnetic field on the surface of the workpiece during the process. Therefore, the objective of this study is to analyze the distribution of electromagnetic force of square working coil for magnetic pulse welding. For this, FE-model has been developed to analyze the distribution of electromagnetic force;after that, distribution of electromagnetic force, results of numerical analysis and experimental results for verifying the developed FE-model were compared. A 3-dimensional electromagnetic FE-model has been developed using a general commercial computer program, ANSYS/EMAG code. The shape and material of square working coil were decided through literature surveys. For the experiment, an MPW equipment W-MPW manufactured by WELDMATE Co., Ltd. was employed;also the materials were the Al 1070, SM45C for Al and Steel square pipe and rod respectively. After the experiment, leakage test was used to verify the weldability. Also weld joints were observed on longitudinal cross-section by microscope. The electromagnetic force generated was the greatest one at the center adjacent to square working coil, decreasing as moving into the edge. As the result of Al/Steel welding experiment, weldment of square Al pipe was not completed at the corner of weldment. These results are similar to the output data from developed electromagnetic FE-model where electromagnetic force decreases as moving into the corners of square working coil.

混合热工和水力特性的风机盘管系统建模

针对风机盘管系统建模研究中大多数未考虑水力学特性对其的影响,本文提出混合热工和水力特性的风机盘管系统建模方法,以满足实际工程中对于风机盘管系统控制的数学模型需要.在水力学模型中考虑风机盘管电动水阀,基于基尔霍夫定律建立水力平衡方程,通过遗传–粒子群相结合的优化算法(GA-PSO)求解各个盘管的水流量及对应的阀门开度;以水流量为输入,考虑风机盘管风量,采用非线性最小二乘法辨识求解其总传热系数,建立基于牛顿冷却定律的风机盘管热力学模型.实验结果表明:混合热工和水力特性的建模方法能够更好的反应风机盘管的物理过程;GA-PSO算法具有很好的稳定性和收敛性,能够更准确的求解水流量及对应的阀门开度,与实际运行数据的相对误差不超过1%;热力学模型在各种实际工况下的模型误差都低于4%,能够精确反映风机盘管的传热过程.

基于物理模型的ISTAVS-Net多线圈MRI图像重建

提高磁共振成像速度是磁共振领域待解决的问题,采用多线圈扫描是一种常用加速方式.但在加速因子大于4时,传统压缩感知磁共振(CS-MRI)重建算法得到的图像质量不高.为此,本文提出一种基于物理模型的ISTAVS-Net多线圈MRI图像重建方法.将ISTA算法与VS-Net网络拆分思想相结合,提出ISTAVS算法,并展开成ISTAVS-Net网络.将每步迭代与网络模块结合,比黑盒U-Net网络的可解释性更强.网络中引入残差机制,增加了网络的非线性表达能力和稳定性.稀疏变换、收缩阈值以及正则化参数在训练中自动学习,提高了重建的灵活性.采用Globus膝关节数据集的测试结果表明不同加速因子下ISTAVS-Net网络效果均优于传统的L1-ESPIRiT和ISTA迭代算法,图像质量和性能指标比U-Net、ISTA-Net+和VS-Net网络提升明显,在高加速因子下对组织细节恢复能力更强.该网络鲁棒性强,更适合对临床扫描数据进行快速高质量重建,可拓宽MRI应用范围.

超磁致伸缩换能器磁场强度建模与线圈优化分析

磁场强度是决定换能器性能的关键变量,为了提高超磁致伸缩换能器(GMA)的磁场强度和输出位移,本文提出了一种新型的弓张式发音振子结构,用COMSOL软件建立二维模型,得到超磁致伸缩材料(GMM)棒内部磁场分布情况。由于弓结构内部空间受限,对激励线圈进行优化,讨论了导线经验模型、静态电阻和电感模型的适用性,建立了线圈的平均磁场模型,以线径为决策变量,计算了正弦响应下不同线径的振幅比和相位滞后。结果表明:该模型在计算电阻和电感时的相对误差分别小于5.3%和4.1%。在预测正弦响应时,计算振幅比的误差低于6.6%(在大多数条件下低于1.8%),计算滞后相位的误差低于3.4%。较宽的导线直径对提高磁场振幅有较大的帮助,但对磁场的相位滞后性影响很小。

螺旋半圆管夹套式余热排出装置传热分析及设计程序开发

提出一种适用于小型反应堆的螺旋半圆管夹套式非能动余热排出装置,利用螺旋半圆管夹套具有的传热效率高、结构紧凑等优点,与反应堆主容器形成一体化的紧凑设计。基于此,对螺旋半圆管夹套的传热过程进行了分析,提出传热计算模型并基于此开发了热工设计程序,通过与公开文献中试验数据的对比分析,验证了程序的正确性,可以用于半圆管夹套式余热排出装置的工程设计。

基于聚类和GBDT的镀锌钢卷力学性能预测

热镀锌钢卷力学性能影响因素之间关系复杂,限制了模型精度的提升。采用k-means算法利用化学成分属性对镀锌钢卷数据集进行聚类,将数据聚成三种模式簇实现样本的优选。利用梯度提升树算法,开展各模式数据集与不划分模式的全数据集下的力学性能建模研究,最后结合网格搜索与交叉验证方法进行模型参数优化。研究结果表明,分模式下模型MAE误差相比于全数据集建模平均减小0.85 MPa。参数优化后,各模式下MAE误差平均减少5.19 MPa,RMSE误差平均减少3.63 MPa,提高了预测模型精度。