Interroll tension model adapted to a secondary annealing process

Due to the special secondary rolling and annealing processes,the physical properties of strip ductility and stress relief differ from those of the general products.The proportional integral differential(PID)algorithm for the annealing furnace tension control and the conventional control method that only controls the total tension of the furnace entrance and exit cannot meet production continuity.Aiming at the tension in the annealing furnace,the interroll tension model of the tension of the steel strip between the adjacent furnace rolls is established.By combining the control principle of the annealing furnace roll transmission mechanism,the tension control involves the motor and frequency converter equipment.The coupling relationship between the stator current and the motor’s output torque was determined through the asynchronous equivalent motor circuit.Also,the direct influence of the load torque on the calculated value of the motor’s output tension was obtained through the motor vector control equation.Furthermore,the frequency converter’s voltage control model was analyzed to control the motor’s output tension.Finally,the adjacent furnace roll tension and the horizontal annealing furnace tension were calculated through the interroll tension model.

Modeling bubble column reactor with the volume of fluid approach:Comparison of surface tension models

This work aims at comparing surface tension models in VOF(Volume of Fluid) modeling and investigating the effects of gas distributor and gas velocity. Hydrodynamics of a continuous chain of bubbles inside a bubble column reactor was simulated. The grid independence study was first conducted and a grid size of 1.0 mm was adopted in order to minimize the computing time without compromising the accuracy of the results. The predictions were validated by comparing the experimental studies reported in the literature. It was found that all surface tension models can describe the bubble rise and bubble plume in a column with slight deviations.

Modified surface tension model for free surface flow with single-phase lattice Boltzmann method

A single-phase lattice Boltzmann model with modified surface tension is developed in this paper to solve the problem of high-density-ratio free surface flow.The computational efficiency and accuracy are both enhanced.The restriction to the relaxation factor （which needs to be smaller than 1） is circumvented by the new surface tension algebra,due to its rational physical nature compared with the treatment of Xing,Buther and Yang in their paper （Comp.Mater.Sci.,2007,39（2）：282-290）.The proposed stable surface tension scheme is applied to simulate the free deformation of a square droplet with surface tension effect and the process of a droplet impinging on a liquid film.The numerical solution for free deformation of a droplet agrees well with thermodynamic principles,and also achieves high accuracy in comparison with Xing,et al.＇s model.Three typical impinging modes are successfully obtained with the new scheme,and another particular mode found by Wang and Chen is also successfully simulated.The evolutions of liquid crown agree well with the power law related to time.

Hubble Tension Explanation from This Cosmological Model AΛΩ (Slow Bang Model, SB)

In this article we present a model of Hubble-Lemaître law using the notions of a transmitter (galaxy) and a receiver (MW) coupled to a model of the universe (Slow Bang Model, SB), based on a quantum approach of the evolution of space-time as well as an equation of state that retains all the infinitesimal terms. We find an explanation of the Hubble tension H0. Indeed, we have seen that this constant depends on the transceiver pair which can vary from the lowest observable value, from photons of the CMB (theoretical [km/s/Mpc]) to increasingly higher values depending on the earlier origin of the formation of the observed galaxy or cluster (ETG ~0.3 [Gy], ~74 [km/s/Mpc]). We have produced a theoretical table of the values of the constant according to the possible pairs of transmitter/receiver in the case where these galaxies follow the Hubble flow without large disturbance. The calculated theoretical values of the constant are in the order of magnitude of all values mentioned in past studies. Subsequently, we applied the models to 9 galaxies and COMA cluster and found that the models predict acceptable values of their distances and Hubble constant since these galaxies mainly follow the Hubble flow rather than the effects of a galaxy cluster or a group of clusters. In conclusion, we affirm that this Hubble tension does not really exist and it is rather the understanding of the meaning of this constant that is questioned.

Calculation of Particle Decay Times in the Standard Model

We present here a two-step method of classification and calculation for decay rates in the Standard Model. The first step is a phenomenological classification method, which is an extended and improved schematic experimental formula for decay width originally introduced by Chang. This schematic formula separates decays into seven classes. Furthermore, from it is derived a process-specific interaction energy mX. The second step is a numerical calculation method, which calculates this interaction energy mX numerically by minimization of action from the Lagrangian of the process, from which follows the decay width via the phenomenological formula. The Lagrangian is based on an extension of the Standard Model, the extended SU(4)-preon-model. A comparison of numerically calculated and observed decay widths for a large selection of decays shows a good agreement.

Calculation Model for Surface Tension of Slag Melt

Based on the coexistence theory of slag melt structure and Butler’s equation,a new calculation model has been proposed for the calculation of surface tension of slag melt.This model establishes a specific correlation between surface tension and mass action concentrations(activities) in the melt and on its surface on the basis of inner and surficial structures of slag melt.Calculated surface tensions of CaO-SiOand MnO-SiOslag melts are consistent with those measured.Furthermore,iso-surface tension lines of CaO-MnO-SiOslag melt have also been calculated.

A 3-DOF Pseudo-Rigid-Body Model for Tension-Based Compliant Bistable Mechanisms

Compliant bistable mechanisms, devices with two distinct stable equilibrium positions, are used in a variety of applications, such as switches, clasps, and valves. Many kinds of compliant bistable mechanisms were proposed and studied during the past decade. Among them, tension-based compliant bistable mechanisms, that incorporate tension pivots as their flexible members, feature in short travel distance and low power consuming. So far, the design of this kind of bistable mechanisms is done using finite element method through trial and error, thus is time-consuming. By treating the tension pivots as fixed-guided segments and their elongation as a spring, we developed a novel three degree-of-freedom （3-DOF） pseudo-rigid-body model （PRBM） for this kind of bistable mechanisms. The principle of virtual work is used to derive the force-deflection relationship of the PRBM model. The comparison between the PRBM results and the experimental results of the force-deflection characteristics shows that the PRBM can predict not only the bistable behavior of the tension-based bistable mechanisms, but also their soft spring-like post-bistable behavior and the spring-like force-deflection characteristics when pulling in the reverse direction from the as-fabricated position, which is called reverse behavior. The 3-DOF PRBM can be used to design and identify tension-based bistable mechanisms. Using the PRBM instead of the trial-and-error method can greatly reduce the development time of this kind of bistable mechanisms.

Simplified Prediction Model for Vortex-Induced Vibrations of Top Tensioned Risers

According to the characteristics of deepwater top tensioned risers, a simplified model is presented to predict the multi-modal response of vortex-induced vibration （VIV） in non-uniform flow based on energy equilibrium theory and the exporimental data from VIV self-excited and forced oscillations of rigid cylinders. The response amplitude of each mode is determined by a balance between the energy fed into the riser over the lock-in regions and the energy dissipated by the fluid damping over the remainders. Compared with the previous prediction models, this method can take fully account of the intrinsic nature of VIV for low mass ratio structures on lock-in regions, added mass and nonlinear fluid damping effect, etc. Moreover, it is the first time to propose the accurate calculating procedure for VIV amplitude correction factor by solving energy equilibrium equation and a closed form solution is presented for the case of a riser of uniform mass and cross-section oscillating in a uniform flow. The predicted values show a reasonable agreement with VIV experiments of riser models in stepped and sheared currents.

基于修正断裂分析模型的混凝土劈拉强度预测

数值分析是规避试验短板、实现理论预期的重要研究手段。该文采用细观尺度数值试验方法,对建立的基于绕晶失效模式的混凝土三维细观断裂理论分析模型进行修正。采用的混凝土数值分析模型由砂浆、界面及骨料组成,与理论分析模型保持一致。为模拟普通强度混凝土的力学行为,采用塑性损伤本构模型表征砂浆和界面的力学性能,骨料则设为弹性球体。采用自编骨料投放程序,建立了截面尺寸分别为100 mm(一级配)、150 mm(二级配)、300 mm(三级配)和450 mm(四级配)的三维模型混凝土标准立方体试件。通过开展不同界面强度条件下标准立方体试件劈裂拉伸加载数值试验,对理论分析模型进行了修正,建立了用于不同级配混凝土劈拉强度预测的半理论-半经验修正计算公式。与数值试验及物理试验结果对比表明:修正后的理论分析模型能够有效表征混凝土宏观力学性能随细观组成材料力学特性和结构特性的变化规律。该文提出的基于重叠效应和结构效应分析的理论模型修正方法,可为后续建立基于修正断裂分析模型的混凝土力学性能半理论-半经验预测公式奠定基础。

基于GMM的湿筛混凝土轴拉损伤演化机制研究

为研究不同加载阶段下的二级配湿筛混凝土开裂模式与损伤演化过程,将声发射技术(AE)与高斯混合模型(GMM)进行结合作为损伤识别手段,以3种加载速率(1×10^(-6)、5×10^(-6)、25×10^(-6)s^(-1))作为试验变量,对二级配湿筛混凝土开展单轴拉伸损伤时空演化机制试验研究。结果表明:随着加载速率增大,湿筛混凝土试件内部裂缝开展更加密集,并且裂缝种类随机性更高;利用GMM法对声发射数据进行处理分类结果显示,拉伸裂缝为试验加载过程的主要开裂模式,加载速率升高会导致剪切裂缝占比增大;随着加载速率增大,拉伸裂缝频率分布明显扩大,而剪切裂缝与混合裂缝频率分布基本不变;随着加载进行,拉伸裂缝与剪切裂缝概率密度区域均向AF轴趋近;GMM法所得裂缝开裂模式有拉伸裂缝、剪切裂缝与混合裂缝3种类别,并且随着加载进行,混合断裂区所处位置也会发生变化;相较于常规裂缝模式分类方法,GMM法提供了更好的裂缝分类近似值分析,对裂缝开裂模式表述更加可靠。

热转印系统色带传动过程张力分析与建模

为保证热转印过程中薄膜色带传动稳定进而实现高质量转印,建立正确的热转印色带传动张力模型十分关键。首先,研究了热转印色带传动系统组成及转印原理,并根据色带传动路径分辊间段、放卷段和收卷段3阶段对色带传动系统张力进行了建模与分析。然后,结合热转印色带卷材的黏弹性分析张力形成机制,改进了卷绕系统经典张力公式,建立了辊间段薄膜色带张力模型。针对传动系统的放卷区域,分析了摩擦对薄膜色带传动张力的影响,提出张力下降系数以评估张力损失。考虑色带张力非线性时变的特点,利用步进电动机负载模型求解收卷区域色带张力。最后,通过对比仿真与实验所得的色带张力变化曲线,验证了模型的准确性,为后续张力控制方案设计奠定了基础。

不同侧张力性气胸对猪血流动力学的影响

目的探讨不同侧张力性气胸对猪血流动力学的影响,为优化气胸现场一线救治流程提供数据支持。方法12只巴马猪随机分为左侧张力性气胸组与右侧张力性气胸组,每组6只。通过脉搏指示连续心输出量监测(PICCO)技术在气胸及以1 mmHg为单位逐渐增大的胸膜腔压力下采集相关指标,包括血流动力学指标[全心射血分数(GEF)、心输出量(CO)、全心舒张末容量(GEDV)、胸腔内血容量(ITBV)、每搏量(SV)、平均动脉压(MAP)]、基础生命体征指标[心率(HR)、舒张压(DBP)、收缩压(SBP)]及动脉血气指标[氧分压(PO_(2))、二氧化碳分压(PCO_(2))],随后使用X线片进行纵隔定位。通过两组之间互相比较及组内前后比较的方式探究其差异性。结果通过比较血流动力学变化及X线片检查结果,12只巴马猪张力性气胸模型均构建成功。血流动力学分析结果显示,左侧张力性气胸在胸膜腔压力为8 mmHg时,与同侧气胸时相比,SBP、DBP、MAP、CO、GEF、SV、GEDV及ITBV明显下降(P<0.05)。右侧张力性气胸在胸膜腔压力为3 mmHg时,与同侧气胸时相比,SBP、DBP、MAP、SV、GEDV及ITBV明显下降(P<0.05)。血气分析结果显示,左侧张力性气胸(胸膜腔压力为8 mmHg)及右侧张力性气胸(胸膜腔压力为3 mmHg)时,与各自同侧气胸时相比,PO_(2)明显降低(P<0.05),PCO_(2)明显升高(P<0.05)。结论不同侧张力性气胸存在差异性,在较小的胸膜腔压力下右侧张力性气胸较左侧更易导致严重后果。进行张力性气胸相关实验时可根据实际情况构建不同侧张力性气胸模型。

常温养护超高性能混凝土弯拉性能及轴拉本构模型

根据水化反应方程和紧密堆积理论确定了常温养护下超高性能混凝土(UHPC)的基础配合比,基于此考虑水胶比和钢纤维掺量设计了8组UHPC抗弯试件。通过四点弯曲试验,分析了试件的受弯破坏形态、荷载-挠度曲线、弯拉特征参数和弯曲韧性等;基于试验结果采用倒推方法得到了UHPC轴拉应力-应变曲线,采用回归分析提出了考虑纤维特征的轴拉本构模型,并经过材料和构件两个层次的验证。结果表明:掺加钢纤维可抑制主裂缝的发展,从而明显改善UHPC的抗弯韧性,钢纤维掺量为2.0%的UHPC弯曲韧性指数达到116.9 J;随着水胶比增大,试件抗折强度和峰值挠度均呈下降趋势;增大钢纤维掺量明显提升了试件弯曲性能,掺入2.0%钢纤维的UHPC与未掺纤维相比,其初裂挠度和抗折强度分别提升157.14%和148.63%;当纤维含量为1.5%~2.0%时,试件具有良好的弯拉性能;水胶比对曲线平台段趋势影响不大,纤维掺量大于1.0%时曲线具有较明显的应变硬化特征,可保证UHPC良好的抗拉性能,其应变硬化特征随着纤维掺量增大而变得更明显;所提模型对UHPC受拉应力-应变关系具有较好的预测性。

基于SOA优化的ADRC胎面卷取张力控制系统

胎面卷取张力控制的精度直接影响后期成型工序的精度和硫化成品质量。为保证胎面成品的质量,以挤出联动线卷取时的张力控制为研究对象,针对胎面制品卷取速度和时变卷径引起的张力波动问题,首先分析系统张力产生机理,建立张力系统的数学模型,设计了系统启动和运行阶段的张力观测算法。其次建立仿真模型在系统启动-运行阶段通过对比自抗扰控制器(active disturbance rejection control,ADRC)与比例-积分-微分(proportional integral derivative,PID)的控制性能,验证了自抗扰控制响应速度快,能够稳定地控制张力,并且具备出色的抗干扰性和抗内部参数扰动能力。最后采用人群搜索算法(seeker optimization algorithm,SOA)筛选控制器参数最优值,将控制器应用到张力系统模型,仿真验证了所设计的人群搜索自抗扰控制策略的有效性和准确性。结果表明:SOA优化性能较好且与ADRC相结合的控制方式控制效果较佳。研究结果在桂林橡胶设计院的工艺方法及性能指标体系上进行控制算法设计,对实际生产具有一定的参考价值。

无粘结环锚预应力衬砌张拉工艺足尺模型试验研究

针对预应力衬砌张拉过程中易出现应力集中而导致张拉裂缝的现象,通过开展洞外地面足尺模型试验,提出了分级分步张拉顺序和质量控制指标。首先根据钢绞线摩阻测试计算出摩擦系数,随后应用上述张拉顺序和质量控制方法进行自动张拉,并采用磁通量传感器和混凝土应变计分别对钢绞线和内衬混凝土的应力变化开展实测。现场张拉试验结果表明:①钢绞线沿程预应力损失约16.3%,采用的双层钢绞线在实践中可保证较高的有效预应力;②对锚具槽进行分级分步张拉,可使内衬混凝土获得较均匀的封闭环向压应力环,平均压应力达-10.9 MPa;③提出的3项控制指标可进行量化管理,结合自动张拉技术可有效地保证张拉质量。

铝粒尺寸及入炉高度对运动轨迹的影响

二次精炼过程中,铝是钢液进行脱氧及合金化的主要物料之一,但纯铝的密度小于钢液,能否穿越渣层与钢液接触及接触时间对铝的脱氧效果和钢中溶解铝的含量有直接影响。在忽略铝的熔化、溶解及化学反应的情况下,通过对铝粒运动过程受力分析,建立铝粒在气-渣-钢相内的三维运动数学模型,明晰铝粒尺寸及入炉高度对铝粒运动轨迹的影响。结果表明:在渣层厚度为70 mm且入炉高度为1~1.5 m的情况下,1 mm和5 mm的铝粒在渣钢界面处波动;入炉高度为1 m时,粒径为10 mm的铝粒停留在渣钢界面处,但在入炉高度为1.5 m及以上时可以进入钢液;20 mm及以上尺寸的铝粒可以进入钢液。在入炉高度为1 m时、30 mm尺寸的铝粒在钢液中的停留时间与深度相较于20 mm的基础上分别增加22.86%和50.00%;在铝粒尺寸为20 mm时、入炉高度为1.5 m时的铝粒在钢液中的停留时间与深度在1 m的基础上分别增加5.71%和10.00%。增加钢渣界面张力、减小钢铝界面张力或增加渣铝界面张力有利于铝粒进入钢液,而铝粒的尺寸大于20 mm,界面张力对铝块运动几乎没有影响;增大密度会使钢芯铝在钢液中停留更长时间,有利于钢液脱氧。

硅锭线切割张力控制方法对比研究

为满足低成本、低切损、高精度、高稳定性的硅片切割要求,在分析常用的两种线切割张力控制方法优缺点的基础上,采用ADAMS软件进行了弹簧式张力控制原理的建模与动力学仿真,并基于Simulink与MFAC控制算法对电控式张力控制进行了ADAMS与MATLAB动力学联合仿真。结果表明,两种张力控制方法所得到的电极丝加速度变化曲线走势一致,电控式张力控制在快速性及精确性方面优于弹簧式张力控制,但平稳性较差。进而,提出弹簧与电控相结合的张力控制方法,并在ADAMS中完成建模与动力学仿真。结果表明,该装置可在一定程度上取长补短。

基于LSTM模型的浮式风机系泊监测数据解算方法

针对浮式风机系泊倾角监测数据如何准确解算为系泊张力响应的问题,提出一种基于长短时记忆(LSTM)网络与全连接网络(FCN)相结合的系泊张力解算模型。首先,针对在役的“扶摇号”浮式风机,建立风-浪-流耦合时域仿真模型,用以获取不同工况下系泊张力与倾角数据,从而形成神经网络的训练与验证数据集。在Keras框架下,开发FCN与LSTM的组合网络模型,选取Adam优化器进行训练,获得验证集损失函数最小的网络参数。最后,分别采用传统悬链线方程与神经网络模型对系泊张力响应进行预测,并与实际结果进行比对分析。结果表明:神经网络能够考虑到不同系泊倾角对应的导缆孔平均高度变化以及系泊运动的动态过程,在系泊张力时程曲线、均值、标准差及最大值等预测上比传统悬链线方程具有更高的精度,两者对于系泊张力最大值的预报误差分别为6.4%和17.1%。

主动激励声波在后张法混凝土传播机理可视化及影响研究

当激振器作为主动激励信号时,不同的激励频率和激励幅值的声波在后张法混凝土结构内的传播机理及影响因素对实际工程提供主动激励信号波形参数选取及声发射传感器布置方式具有重要意义。该文利用COMSOL数值模拟方法可视化了激振器激励声波在后张法混凝土梁内的传播机理,提出了激振器主动激励信号波形参数确定的方法。结果表明:数值模拟方法可视化了激振器激励声波在后张法混凝土结构内的传播路径;构建了不同激励频率和激励幅值声波在后张法混凝土结构内衰减模型,可作为稳定的主动激励信号波形参数选取和声发射传感器布置方式的理论基础,当激励幅值相同,激励频率为10 kHz时,激励声波在后张法混凝土结构内衰减系数最小,实际工程中为保证信噪比,较大的激励幅值更有优势。