共查询到17条相似文献,搜索用时 93 毫秒
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本文基于牛顿冷却规律给出了“冰的熔解热实验”中用外推法修正温度的完整的理论依据.采用Matlab编程实现了修正温度时面积补偿的要求,将其用于数字温度计所得实验数据的处理,计算得到的熔解热值基本符合预期.通过理论分析和数值计算发现,采用外推法处理实验数据基本上不依赖于冰、水质量以及投冰时水温等实验参数的设置,而环境温度测量虽然影响散热系数的计算,但对温度的修正与熔解热的计算影响很小,因此,基于该方法的熔解热测量很适合在实验条件要求不高的物理实验教学中推广应用. 相似文献
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在高二物理物态变化一章里,常会遇到冰水混合的問題。由于学生思維不够周密,加上对熔解热的概念理解不够透澈,故在計算当中往往会得出錯誤的結果。下面就是一个具体的例子: 在盛有200克、8℃的水的量热器中,投入一块300克—20℃的冰。在热平衡时,量热器 相似文献
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在高二物理物态变化一章里,常会遇到冰水混合的問題。由于学生思維不够周密,加上对熔解热的概念理解不够透澈,故在計算当中往往会得出錯誤的結果。下面就是一个具体的例子: 在盛有200克、8℃的水的量热器中,投入一块300克—200℃的冰。在热平衡时,量热器里的物体的温度是多高?(朱波夫、沙里諾夫合著物理学习題集第233題。) 学生的錯誤情况是: 設:冰水混合后終温为t,則200克水由 相似文献
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Chengxiang Zhu Chunling Zhu & Tao Guo 《advances in applied mathematics and mechanics.》2016,8(5):737-756
A mathematical multi-zone ice accretion model used in the numerical simulation
of icing on airfoil surface based on three water states, namely, continuous film,
rivulets and beads is studied in this paper. An improved multi-zone roughness model
is proposed. According to the flow state of liquid water and film flow, rivulets flow
governing equations are established to calculate film mass distribution, film velocity,
rivulet wetness factor and rivulet mass distribution. Force equilibrium equations of
droplet are used to establish the critical conditions of water film broken into rivulets
and rivulets broken into beads. The temperature conduction inside the water layer and
ice layer is considered. Using the proposed model ice accretion on a NACA0012 airfoil
profile with a $4^◦$ angle of attack under different icing conditions is simulated. Different
ice shapes like glaze ice, mixed ice and rime ice are obtained, and the results agree well
with icing wind tunnel experiment data. It can be seen that, water films are formed on
the surface, and heights of the films vary with icing time and locations. This results in
spatially-temporally varying surface roughness and heat transfer process, ultimately
affects the ice prediction. Model simulations indicate that the process of water film
formation and evolution cannot be ignored, especially under glaze ice condition. 相似文献
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渤海海冰反射光谱基本特征的观测研究 总被引:3,自引:0,他引:3
针对渤海海冰监测的需要,在分析前人相关研究的基础上, 从洁净平整冰入手, 通过控制实验,在辽东湾鲅鱼圈港内获取不同厚度的洁净平整冰、有积雪覆盖海冰和含有泥沙海冰的样本,开展海冰现场反射光谱观测实验。根据两年的观测数据, 在可观测到的小于30 cm厚度范围内,洁净平整冰的光谱曲线呈现出“一大一小” 的双峰特征,且主反射峰值与海冰厚度有较好的对应关系;有积雪覆盖海冰的主反射峰光谱值要大大高于相同厚度的没有积雪覆盖的洁净平整冰主反射峰光谱值;含有泥沙的海冰的光谱曲线在675~725 nm波长范围内表现为先略有抬升,然后再继续下降的特征,而且其主反射峰值也大大升高。积雪覆盖和泥沙是产生渤海海冰“同厚异谱”或“同谱异厚”现象的重要原因。 相似文献
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H. Meyer L. Schönicke U. Wand H. W. Hubberten H. Friedrichsen 《Isotopes in environmental and health studies》2013,49(2):133-149
Abstract Equilibration technique suitable for a large amount ofsamples is described for hydrogen and oxygen isotope analyses of ground ice, especially ice wedges, including the sampling strategy and the analytical procedure as well as the calibration of the Finnigan MAT Delta-S mass spectrometer in June, 1999. Since for future analyses of ice wedges, a higher sampling resolution with limited sample volume is required, the limit of the equliibration technique for small water samples size of between 0.05 and 5 ml was checked. For water samples smaller than 1ml, corresponding to a molar ratio [H2O]/[H2] of smaller than 0.994, a balance correction has to be applied. The experimental errors due to partial evaporation during evacuation, the balance calcultion of the isotope equilibration process, the linearity as well as memory effects of the mass spectrometer for smaples with large differences in δ18O and δD are tackled in this paper. In the polar regions of Northern Siberia without Late Pleistocene and Holocene glaciation, ground ice is used as an archive for paleoclimate studies. First results of stable isotope measurements on ice wedges clearly show a shift towards heavier isotopes and thus warmer winter temperatures as well as a change in the source of the precipitation between Late Pleistocene and Holocene. These results indicate the high potential of ground ice for paleoclimate studies. 相似文献
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J.S. Wettlaufer 《Interface Science》2001,9(1-2):117-129
The dynamics of faceted and partially faceted single crystal and polycrystalline ice are reviewed with an emphasis on the manner in which microscopic effects produce macroscopic shapes. Our understanding of the former is rooted in the basic kinetics common to all materials and our pursuit of the latter is largely motivated by the striking patterns exhibited in the natural environment when water changes phase to become ice. 相似文献
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Menzel MI Han SI Stapf S Blumich B 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2000,143(2):376-381
NMR imaging and one- and two-dimensional self-diffusion propagator measurements of the liquid phase in salt water ice are presented. The properties of the network of brine-filled pores are found to depend on the growth conditions of the ice. Two types of samples are compared: (a) shock-frozen ice produced in the probe in situ and (b) ice grown over several hours under controlled conditions. By shock-freezing, an ice structure could be produced which featured streak-like porous channels of diameters of up to 300 μm allowing almost unrestricted self-diffusion along one preferential axis but reduced diffusivities in the remaining directions. In ice grown under controlled conditions, the pore sizes are near the resolution limit of the imaging experiment of typically 50 μm. For this type of samples, strongly non-Gaussian self-diffusion propagators are obtained, indicating restricted self-diffusion on rms scales of 30 μm. Common to all samples was the observation of highly anisotropic self-diffusion. One- and two-dimensional propagators are compared in order to estimate the degree of anisotropy and the size of the restrictions. 相似文献