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介绍了一种用于原子气室的无磁加热薄膜技术。原子磁力仪、原子陀螺仪、原子钟等采用热原子系综的精密测量仪器通常采用原子气室作为物理系统,为了保证足够的原子数密度,原子气室工作温度通常为80~120℃,因此无磁加热技术是热原子钟的核心技术之一。采用多物理场有限元仿真分析通电线圈在小电流(直流0.2 A)条件下产生的稳态磁场分布情况,通过对比不同线圈结构产生的磁场分布,得到满足性能要求的通电线圈结构。实验结果表明,采用优化后结构的无磁加热薄膜产生的剩磁低于100 nT,满足原子气室无磁加热要求。该设计对以原子气室的原子钟性能提升提供了可靠保证,并为原子钟小型化提供参考。 相似文献
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基于ANSYS的脉冲激光辐照石英玻璃的温度场数值模拟 总被引:2,自引:0,他引:2
采用有限元仿真软件ANSYS 12.0对脉冲功率激光辐照石英玻璃建立了热力学模型,对其表面温度场进行了数值模拟,得到了在不同激光功率密度下的瞬态温度场分布,并对模拟结果进行了分析和研究,为激光辐照石英玻璃实验提供依据. 相似文献
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本文提出一种在两片软包电池中间加入双向加热膜的加热方案。测试了软包电池在两种倍率下不同温度时的电压响应,低温下电池的放电容量大幅下降。比较了LCP加热和加热膜加热的加热性能,加热膜的综合因子为0.61,加热性能较好。实验表明,加热膜的功率变大时,电池表面最高温度和温差均会升高,因此对此加热方案进行了优化。设计了四种加热膜排布方式,结果表明,采用方案四的分布方式电池表面最高温度为32.8?C,温差为0.62?C。最后,采用方案四将电池从-20?C开始加热,比较了不同起始温度的电压和容量大小。 相似文献
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涡流热成像可以对金属材料表面、近表面缺陷进行快速准确的检测。采用涡流热成像与脉冲相位分析相结合的方法,针对裂纹附近相位谱的分布规律及温度场对相位谱的影响关系问题,分别对带有上表面裂纹和下表面裂纹的45#钢料进行感应加热仿真和实验分析。结果表明,相位谱分布与温度大小无关,只与温度变化趋势有关,相位谱图对不均匀加热有很好的抑制作用,可以扩大裂纹的检测范围,当频率低于12.5 Hz时能够清晰地识别裂纹。结合实验验证了仿真结论的正确性,为下一步利用相位信息实现缺陷的定量检测提供参考。 相似文献
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在材料科学和材料工程领域,对受热材料温度分布测量的需求一直在持续增长。这主要是因为对于材料的各种特性和行为,温度都是其重要参量。本文设计一种新的声表面波测量方法测量在加热或冷却过程中的材料表面的温度梯度。这种方法涉及到超声波回波测量和导热反问题的分析方法来得到材料中沿超声传播方向的一维温度场分布。为了证明方法的可行性,文章使用铝板进行了实验并得到了准确的材料表面温度场分布图像。超声测温技术将作为一种新型的热点技术,将有很大潜力被用在工业材料高温操作过程中的表面温度场成像。 相似文献
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在综合考虑热源模型、对流辐射换热、相变潜热、材料非线性因素对激光沉积修复温度场影响前提下,建立了激光沉积修复的数学模型,采用有限元参数化设计语言(APDL)对多道多层激光沉积修复温度场进行了数值模拟。研究了激光沉积修复瞬时温度场及其中心高度上节点温度随时间变化情况,分析了修复件中心高度上温度梯度分布情况。搭建了激光沉积修复温度测量系统,对修复时表面温度进行了测量,并与模拟温度进行了比较,两者吻合较好。为控制激光沉积修复组织、提高修复质量提供有效手段。 相似文献
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基于局域热平衡状态假设并考虑金属蒸汽的作用, 建立了钨极惰性气体保护焊电弧与熔池交互作用的三维数学模型. 电弧等离子体的热力学参数和输运系数由温度和金属蒸汽浓度共同决定, 并使用第二黏度近似简化处理金属蒸汽在氩等离子中的输运过程. 在考虑熔池流动时, 主要考虑了浮力、电磁力、表面张力和等离子流拉力的作用. 通过对麦克斯韦方程组、连续性方程、动量守恒方程、能量守恒方程和组分输运方程的耦合求解, 得到了金属蒸汽在电弧中的空间分布、电弧和熔池的温度场、速度场和电流密度分布等重要结果. 通过与未考虑金属蒸汽的结果对比, 研究了熔池上表面产生的金属蒸汽对电弧等离子体行为的影响, 以及电弧等离子对熔池行为的影响. 结果表明, 金属蒸汽主要富集在熔池上表面附近; 金属蒸汽对电弧等离子体有明显的收缩作用, 而对等离子速度和电势影响较小; 金属蒸汽的出现对熔池上表面速度分布和剪切力分布以及熔池形貌并无明显影响. 求解结果与已有的实验结果和计算结果符合良好. 相似文献
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T. Li Q. Lou J. Dong Y. Wei J. Liu 《Applied Physics A: Materials Science & Processing》2000,71(3):271-276
Numerical calculations based on a thermal model were presented, which describe the process of target heating and ablation
of cobalt during irradiation by 30-ns laser pulses at 308 nm. The attenuation of laser by vapor has been taken into account
in this model. As results of the calculations, the temperature distribution beneath the target surface and the temporal evolution
of surface temperature were given. The dependence of ablation rate on laser fluence was also studied based on this model.
The surface ablation of cobalt with pulsed excimer laser was investigated experimentally. Our model considering proper vapor
attenuation has shown to be in good agreement with the experimental results.
Received: 20 January 2000 / Accepted: 13 March 2000 / Published online: 5 July 2000 相似文献
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A. I. Grigor’ev 《Technical Physics》2004,49(5):559-564
Processes occurring when a metal electrode dipped in an electrolyte is heated by intense evaporation of the electrolyte are
considered in terms of a physically rigorous model. Based on the Onsager principle of least energy dissipation rate in nonequilibrium
processes, the fractions of thermal energy that are spent on heating and evaporating the electrolyte and on heating the vapor
are found. The energy is released within the vapor-gas sheath when an electric current flows between the electrode and electrolyte
surface. It is found that the electrolyte vapor temperature exceeds 1300 K. Analytical expressions are derived for the vapor-gas
sheath thickness, the electrolyte vapor pressure, and the velocity of the vapor escaping the discharge zone. It is shown that
field evaporation of thermally activated negative ions from the electrolyte surface cannot provide an electric current with
densities found in experiments but is responsible for the generation of free electrons near the electrolyte surface. These
electrons arise when the ions decay via collisions with excited molecules. 相似文献
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Explosion vaporization of a water layer of different thickness, induced by pulse heating in an inhomogeneous temperature field
on the surface of a flat microheater coated with a submicron silicon-carbide layer, is experimentally studied. An optical
method is used for recording the vaporization time history and dynamics of the steam blanket. Pulsed laser irradiation is
applied for high-time-resolution photography of the vaporization process. The dynamics of filling the heater surface with
the vapor phase and the lifetime of the main vapor bubble and the satellite bubble are estimated. Dependences of the vaporization
temperature on the heater temperature growth are obtained. The initial temperature is 30°C; the temperature growth rate on
the heater surfaces is about 180 MK/s. 相似文献
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Molecular dynamics simulations have been used to compute the surface tension of linear alkanes. The OPLS force field has been compared with the SKS force field for alkanes (n-hexane, n-decane and n-hexadecane) over two ranges of temperature: high temperatures where no experimental data are available for surface tension and lower temperatures where comparisons may be made with experiments. At high temperatures, for a given coexistence density, these two models predict a similar surface tension. For a given temperature the two models yield different surface tensions. However, these deviations can be attributed to differences in the prediction of the coexistence curves. For the SKS model the computed coexistence properties have been compared with experimental data. The simulation data are in reasonable agreement with the experimental data. 相似文献
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<正>We investigate experimentally and analytically the combustion behavior of a high-metal magnesium-based hydroreactive fuel under high temperature gaseous atmosphere.The fuel studied in this paper contains 73%magnesium powders.An experimental system is designed and experiments are carried out in both argon and water vapor atmospheres. It is found that the burning surface temperature of the fuel is higher in water vapor than that in argon and both of them are higher than the melting point of magnesium,which indicates the molten state of magnesium particles in the burning surface of the fuel.Based on physical considerations and experimental results,a mathematical one-dimensional model is formulated to describe the combustion behavior of the high-metal magnesium-based hydro-reactive fuel.The model enables the evaluation of the burning surface temperature,the burning rate and the flame standoff distance each as a function of chamber pressure and water vapor concentration.The results predicted by the model show that the burning rate and the surface temperature increase when the chamber pressure and the water vapor concentration increase,which are in agreement with the observed experimental trends. 相似文献
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《Current Applied Physics》2020,20(4):498-504
Vertically-aligned carbon nanotubes (VCNTs) are used as electron source in various field emission applications owing to its high aspect ratio, chemical inertness, mechanical strength and electrical conductivity. Here, we demonstrate that surface structure modification along with thin film coating enhances the field emission performance, such as turn-on voltage, emission site density, and stability. In the present study, VCNTs with different heights were grown on silicon wafers by thermal chemical vapor deposition followed by the structure modification of VCNTs using capillarity-driven water vapor condensation. We obtained various surface morphologies by varying the water vapor exposure time and heating temperature. In addition, the structure-modified VCNTs surfaces were coated with W and SiO2 thin films using electron-beam evaporation. It was observed that W-coated VCNTs with modified surface morphology results in the best field emission performance. 相似文献
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精确的气体光谱参数对气体浓度、温度等的光谱精确反演测量具有十分重要的意义,针对当前主流光谱数据库(例如HITRAN)中数据与实际数值存在相当误差的问题,自主研制了一套基于静态冷却技术的低温光谱实验平台,用于精确测量低温下的气体吸收光谱参数.运用该低温光谱实验平台,采用可调谐二极管激光吸收光谱(TDLAS)技术测量了温度为230—340 K、压强为10—1000 Pa时7240—7246 cm~(-1)波段的纯水汽振转跃迁光谱.采用Voigt线型多峰拟合方法,获得了5条水汽振转跃迁谱在不同温度、不同压强下的积分吸光度值及洛伦兹展宽值,运用线性拟合的方法得到这5条吸收线的自展宽半峰全宽系数及参考温度下的线强值.运用不确定度传递公式,计算得到实验结果的不确定度,与HITRAN2012数据库中的线参数进行对比,所测的5条吸收线中实验结果与数据库值最大相差10.96%,且实验结果的不确定度为1.11%—2.98%(置信概率p=95%,包含因子k=2),小于HITRAN2012数据库值的不确定度. 相似文献