Dynamic response in two-dimensional transversely isotropic thick plate with spatially varying heat sources and body forces

This paper deals with a two-dimensional （2D） problem for a transverselyisotropic thick plate having heat sources and body forces. The upper surface of the plate is stress free with the prescribed surface temperature, while the lower surface of the plate rests on a rigid foundation and is thermally insulated. The study is carried out in the context of the generalized thermoelasticity proposed by Green and Naghdi. The governing equations for displacement and temperature fields are obtained in the Laplace-Fourier transform domain by applying the Laplace and Fourier transforms. The inversion of the double transform is done numerically. Numerical inversion of the Laplace transform is done based on the Fourier series expansion. Numerical computations are carried out for magnesium （Mg）, and the results are presented graphically. The results for an isotropic material （Cu） are obtained numerically and presented graphically to be compared with those of a transversely isotropic material （Mg）. The effect of the body forces is also studied.

Effects of Transverse Field on Internal Energy and Specific Heat of a Molecular-Based Materials

The molecular-based magnetic materials AFe11 Fe111（C2O4）3 have a honeycomb structure in which FeII （S = 2） and FeIH （S= 5/2） occupy sites alternately. They can be described as mixed spin-2 and spin-5/2 Ising model with ferrimagnetic interlayer coupling. The influences of the transverse field on the internal energy and the specific heat of the molecalar-based magnetic system have been studied numerically by using the effective-field theory with self-spin correlations and the differential operator technique.

Influence of the Channel Design on the Heat Exchange Characteristics of Pulsating Flows in the Supply System of an Engine

Heat engines based on reciprocating machines remain in demand as energy converters in a variety of industries around the world.The aim of the study was to evaluate the gas-dynamic,consumable and heat exchange characteristics of non-stationary air flows in a supply system with transverse profiling of valve channels based on experimental studies.Valve channels with cross sections in the form of a circle,square and triangle were used to control the consumable and heat exchange characteristics of the flows in the supply system of the reciprocatingengine model.The article presents data on changes in local velocity,volumetric airflow and instantaneous heat transfer coefficient of non-stationary airflow in supply systems with different valve channel designs.A spectral analysis of the pulsations of the local heat transfer coefficient was also performed.The Nusselt number was calculated for the studied supply systems.The figured valve channels lead to an increase in the volumetric airflow through the supply systemupto32%comparedwiththe basic configuration.The useof a square valve channel leads to suppression of heat transfer(drop is about 15%)compared to the basic supply system,and the use of a triangular valve channel causes an intensification of heat transfer(growth is about 17.5%).The obtained data can be useful for refining mathematical models,adjusting machine learning algorithms,and improving design methods for supply systems of reciprocating machines to improve their technical,economic,and environmental characteristics.

Feasibility Research on Application of a High Frequency Induction Heat to Line Heating Technology

The purpose of this paper is to investigate the feasibility of high-frequency induction heat for the line heating process through a series of experimental studies and numerical calculations. The results show that the heating temperature of induction heating meets the demands of steel plate bending, and the deformation of a steel plate heated by induction heating can achieve the same effect as flame heating. Meanwhile, the finite element model of moving induction heating of the plate is developed, and the comparison of the residual strain fields and transverse shrinkage between these two kinds of heating shows that great similarity has been achieved.

Dual solutions of MHD stagnation point flow and heat transfer over a stretching/shrinking sheet with generalized slip condition

An analysis was made to study the steady momentum and heat transfer characteristics of a viscous electrically conducting fluid near a stagnation point due to a stretching/shrinking sheet in the presence of a transverse magnetic field and generalized slip condition. Two flow problems corresponding to the planar and axisymmetric stretching/shrinking sheet were considered. By means of similarity transformations, the obtained resultant nonlinear ordinary differential equations were solved numerically using a shooting method for dual solutions of velocity and temperature profiles. Some important physical features of the flow and heat transfer in terms of the fluid velocity, the temperature distribution, the skin friction coefficient and the local Nusselt number for various values of the controlling governing parameters like velocity slip parameter, critical shear rate, magnetic field, ratio of stretching/shrinking rate to external flow rate and Prandtl number were analyzed and discussed. An increase of the critical shear rate decreases the fluid velocity whereas the local Nusselt number increases. The comparison of the present numerical results with the existing literature in a limiting case is given and found to be in an excellent agreement.

Hall Effect on ECF Flow along a Rotating Infinite Porous Plate in the Presence of Transverse Magnetic Field

Unsteady extracellular fluid (ECF) flow along with a rotating infinite vertical porous plate in the presence of a transverse magnetic field has been studied numerically. The dimensional governing equations have been non-dimensionalized by useful dimensionless variables. The explicit finite difference method has been used to solve dimensionless equations. The numerical results have been calculated by studio developer FORTRAN 6.6a and MATLAB 2018a. For perfect conducting case, Magnetic Diffusivity Parameter 5 ≤ Pm ≤ 15 has been taken in induction equation. For good accuracy, stability and convergence analysis have been analyzed. Mesh Sensitivity test, steady-state solution test, and code validation test have been performed. For time step τ = 1, the numerical results have been found for the primary velocity, secondary velocity, angular velocity, primary induced magnetic field, secondary induced magnetic field, temperature as well as shear stresses along x and z direction, couple stress along z direction, current densities along x and z direction and the Nusselt number. Finally, the effects of various parameters have been separately discussed and illustrated graphically.

横向感应加热装置功率因数的研究与优化

横向磁通感应加热技术因其连续加热金属薄板带材的优异性能一直是近年来研究的焦点。为了满足节能环保要求,提高加热系统的功率因数可加强系统能源的利用率同时降低设备的成本。基于对45钢薄带加热需求设计了横向感应加热装置,采用有限元数值模拟的方法研究结构参数与电激励参数对横向感应加热系统功率因数的影响,并结合各参数对加热系统功率因数的影响规律对加热模型进行优化。结果表明,优化后模型与初始模型相比,系统的功率因数上升0.048,相对不均匀度下降5.15℃。优化后的模型有效地提高了系统的功率因数,并改善了带材的温度均匀性。

预制T梁架设阶段横向温度梯度作用侧向变形研究

为控制大跨预制混凝土T梁架设阶段由横向温差导致的侧向失稳,以标准截面预制混凝土T梁为背景,对架设阶段横向温度梯度作用下的T梁侧向变形进行研究。建立截面热传递理论模型,通过热传递有限元分析得到主梁温度时程与分布,并与实测结果对比以验证有限元分析准确性,分析极端环境条件下(最高气温、最低气温、最大温差和最强太阳辐射)截面横向温度梯度分布,提出横向温度梯度多线性分布模式和预制混凝土T梁在横向温度梯度作用下的侧向变形简化分析方法。结果表明:热传递有限元分析计算结果与实测结果吻合;混凝土T梁顶、底板温差明显,且均产生较大的横向温度梯度;顶、底板及腹板的最高温度均出现在太阳直射边缘,最低温度出现在横向中心位置附近;采用简化分析方法计算预制混凝土T梁在横向温度梯度作用下的侧向变形,并得到不同标准截面梁在极端横向温度梯度下的侧向变形与跨径的关系,可为预制混凝土T梁架设时侧向变形控制提供参考。

基于多岛遗传算法与响应面法的横向磁通感应加热装置参数优化设计

对金属带材进行横向磁通感应加热(TFIH)时,通常会存在加热温度分布不均匀以及加热温度偏离目标值两个问题。该文研究了加热器结构参数与电源参数对45号钢带材回火热处理温度的影响,并对两种参数分别进行优化,使带材在加热器出口处的平均温度达到目标值600℃,同时获得均匀的温度分布。采用Morris法对加热器结构参数进行全局灵敏度分析,选取显著影响相对不均匀度的参数并建立径向基函数(RBF)神经网络预测模型。使用多岛遗传算法(MIGA)对筛选的结构参数进行优化,初步获得均匀的温度分布。最后以降低温度分布的相对不均匀度和达到理想平均温度为目标,在优化后的加热器结构基础上使用响应面法(RSM)优化电源参数,实现多目标优化设计。仿真验证结果表明,45号钢带材在加热器出口处的平均温度为600.06℃、相对不均匀度为2.36%,满足45号钢回火热处理的要求。

横向加热石墨炉原子吸收光谱法测定茶叶中铅和镉

研究了横向加热石墨炉原子吸收光谱法测定茶叶中铅和镉,用磷酸二氢铵和硝酸镁作混合基体改进剂,消除基体干扰,铅和镉的检出限分别为0.0078和0.0015μg·g^(-1);相对标准偏差为:铅小于9.1％、镉小于5.0％;回收率为95％～114％。

横纹管污垢性能的实验研究

在实验室进行了横纹管的传热性能实验,得出了横纹管管内强制对流换热关联式。以硬度 800mg/L 的人工硬水作为工质,在流速 0.38m/s,管外水浴温度 60℃和相同管内工质入口温度的条件下,进行了横纹管及其对应光管管内污垢的对比实验。结果表明,横纹管不仅有较好的传热性能,还有较好的阻垢性能。

昆虫病原线虫(Steinernema longicaudum BPS品系)生物学测定

研究旨在明确采自北京平谷圣泉庵橡树根际土壤中昆虫病原线虫(Steinernema longicaudum BPS)的生物学特性,进而明确开发应用的可能性。结果显示:在剂量10和20IJs/幼虫下,BPS对寄主幼虫的侵染效果相近,大蜡螟的校正死亡率分别为40.0%和36.7%,黄粉甲的分别为50.0%、53.3%;在剂量40、80、160IJs/幼虫下,BPS的侵染力随剂量的增高而增大,大蜡螟和黄粉甲的校正死亡率分别为73.3%、86.7%、90.0%和70.0%、80.0%、90.0%;在剂量320和640IJs/幼虫下的侵染效果(校正死亡率100%)相近。BPS经40℃水浴处理1h校正死亡率达98%,处理3h,线虫100%死亡;经37℃、36℃和34℃水浴处理10h,校正死亡率分别为92.4%、55.4%和45.7%,处理20h,线虫100%死亡。该线虫在30℃条件下的水平运动能力比在18℃和25℃的强,有34.6%的线虫用24h的时间运动到3.6cm处。研究结果表明BPS具有较强的侵染力、耐热性和水平扩散能力,据此初步分析BPS具有被开发应用潜能。

利用横向槽改善气膜冷却效率的数值研究

为了获得横向槽对气膜冷却效率的影响规律,采用数值模拟方法分别研究了横向槽出口有无斜坡两种冷却结构形式在不同吹风比条件下的流动过程和冷却效率分布情况,并与常规气膜孔冷却结构形式进行了对比,以揭示横向槽对改善气膜冷却效率的机理。研究表明:在横向槽的作用下,射流向主流的垂直扩散受到抑制,二次流在流出横向槽后能更好的贴覆绝热壁面,提高了气膜冷却效率,并且横向槽出口有斜坡的气膜冷却结构在气膜孔中心线上的冷却效率最好。

横向加热石墨炉原子吸收法测定蘑菇、茶叶中的铬和铍

采用横向加热石墨炉原子吸收法测定蘑菇、茶叶中的铬和铍。以MgNO3 作为基体改进剂 ,提高了测定铍的灰化温度和灵敏度 ,很好消除了基体干扰。方法简便、快速、准确度高。铬和铍的线性范围分别为0～ 80、0～ 8μg/L ;特征量分别为 5 .3× 10 -12 g和 1.9× 10 -12 g ;相对标准偏差分别为 3.0 %～ 17.3%和 4 .3%～ 11.6 % ;回收率分别为 98%～ 10 3%和 98%～ 10 6 % ;检出限分别为 6 6和 4 .8ng/ g。

污水源热泵系统污水干渠横向取水研究

从实际工程遇到的取水问题出发,以水泵运行流量和排水口处水深为控制因素,利用非均匀 渐变明渠流理论进行分析,得到了最小自流高差、最大取水量及取排水口间距范围的关系式,为污水 热能利用工程的取排水设计及施工提供参考．

新型横向磁通感应加热线圈

由于横向磁通感应加热装置依然存在装置出口处沿带材宽度方向上带材表面温度分布不均匀的问题,制约其工业应用。感应加热器线圈形状和位置对带材表面涡流分布、温度分布和电磁力分布都会产生重要影响。本文提出一种新型横向磁通感应加热线圈结构,并在同等输入电流、相同规格被加热带材和同等气隙厚度条件下,与两种典型线圈结构进行比较。利用有限元方法进行三维仿真计算得到的运动带材表面的磁感应强度、涡流、热源和温度分布说明本文提出的感应线圈结构在保证效率的同时能够获得更为均匀的出口温度,为新型带材横向磁通感应加热装置的制作提供了理论依据。

水火弯板成形因素对横向收缩量的影响

水火弯板自动化的研究需要定量化地确定横向收缩量。本文采用实验和有限元分析相互结合的方法来研究线加热过程中的横向收缩量。首先,利用水火弯板实验的结果标定有限元分析中呈高斯分布的热源模型参数,而后利用数值模拟的方法探讨水火弯板成形因素对横向收缩量的影响。这些因素包括自然对流换热系数、有无水冷、热源速度、加热焰道长度、燃气流量和横向曲率半径。研究结果表明:自然对流换热系数和横向曲率半径对横向收缩的影响很小;跟踪水冷可以形成有效的收缩;不同燃气流量的热输入有不同的横向收缩变形。本文提出了综合考虑火焰速度、火焰有效功率、火焰作用半径和钢板厚度的热源体能量模型,该模型可以更好地反映这些热输入影响参数所引起的综合作用。

金属材料对激光的热吸收效应

复制法激光打孔，激光束的横向模式决定着加工孔的形状和尺寸精度．从理论上分析了金属材料对激光的热吸收效应，进而通过预热工艺来改善激光束模式在材料表面上的热作用效果，使ＪＧ－２型固体激光器加工精度从设计给定的±０．０３ｍｍ，提高到±０．０１ｍｍ；实施工艺简单易行．

新型封闭室内空气净化技术研究

用横向线－网电极结构、负高电压供电来产生对人体健康有利的负离子；用电晕线加热方法来降低对人体健康不利的臭氧浓度和提高室内负离子浓度．实验研究结果表明，电晕线加热有利于电晕放电进行．在相同电压下，电晕线表面温度升高，负离子流随之升高；在电晕电流、负离子流一定情况下，电晕线加热可降减少臭氧产生，降低封闭室内的臭氧浓度．通过本技术研制的负离子空气净化器样机满足人们对负离子（１０２／ｃｍ３）和臭氧质量浓度ρ（Ｏ３）（≤１２０μｇ／ｍ３）的要求．

横纹槽管结构优化的正交数值模拟试验研究

运用正交试验法设计了横纹槽管结构优化的试验,试验运用数值模拟方法进行,采用标准K-ε方程湍流模型和速度分布两层模型进行模拟计算,研究了横纹槽管结构参数e/d,p/d,a/e和流动Reynolds数对热阻力性能的影响.试验结果表明:在试验参数范围内,影响横纹槽管综合传热性能的主要结构参数为肋节距p/d和肋形a/e,而肋高e/d影响较小,并且传热综合因子随流动Reynolds数增大而迅速降低.通过分析正交试验结果,提出了较佳横纹槽管管型.