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相关概念视频

Thermal expansion and Thermal stress: Problem Solving01:27

Thermal expansion and Thermal stress: Problem Solving

1.3K
San Francisco's Golden Gate Bridge is exposed to temperatures ranging from -15 °C to 40 °C. At its coldest, the main span of the bridge is 1275 m long. Assuming that the bridge is made entirely of steel, what is the change in its length between these temperatures?
To solve the problem, first, identify the known and unknown quantities. The initial length (L) of the bridge is 1275 m, the coefficient of linear expansion (α) for steel is 12 x 10-6/°C, and the change in...
1.3K
Thermal Stress01:09

Thermal Stress

2.6K
If the temperature of an object is changed while it is prevented from expanding or contracting, the object is subjected to stress. The stress is compressive if the object expands in the absence of constraint and tensile if it contracts. This stress resulting from temperature change is known as thermal stress. It can be quite large and can cause damage. To avoid this stress, engineers may design components so they can expand and contract freely. For instance, on highways, gaps are deliberately...
2.6K
Thermal Strain01:19

Thermal Strain

2.3K
Thermal strain is a concept that arises when we consider how temperature changes affect structures. Unlike the conventional assumption that structures remain constant under load, real-world scenarios often involve temperature fluctuations that can significantly impact these structures. Consider a homogeneous rod with a uniform cross-section resting freely on a flat horizontal surface. If the rod's temperature increases, the rod elongates. This elongation is proportional to the temperature...
2.3K
Joule-Thomson Effect01:21

Joule-Thomson Effect

5.4K
The Joule-Thomson effect, also known as the Joule-Kelvin effect, describes the temperature change of a fluid when it is forced through a valve or porous plug while keeping it in a thermally insulated environment. This experiment is called a throttling process. This is an important effect widely used in refrigeration and the liquefaction of gases.
This experiment forces high-pressure gas through a throttle valve or a porous plug to a lower-pressure region. The gas expands as it passes through to...
5.4K
Temperature and Thermal Equilibrium01:11

Temperature and Thermal Equilibrium

7.2K
Heat and temperature are essential concepts for everyone every day. The study of heat and temperature is part of an area of physics known as thermodynamics. It is not always easy to distinguish heat and temperature.
The concept of temperature has evolved from the common concepts of hot and cold. The scientific definition of temperature explains more than just our sense of hot and cold. Temperature is operationally defined as the quantity measured with a thermometer. Furthermore, temperature is...
7.2K
Thermal Sigmatropic Reactions: Overview01:16

Thermal Sigmatropic Reactions: Overview

2.2K
Sigmatropic rearrangements are a class of pericyclic reactions in which a σ bond migrates from one part of a π system to another. These are intramolecular rearrangements where the total number of σ and π bonds remain unchanged.
Sigmatropic shifts are classified based on an order term [i, j ], where i and j indicate the number of atoms across which each end of the σ bond migrates. Below are examples of a [3,3] sigmatropic shift in...
2.2K

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相关实验视频

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High-resolution Thermal Micro-imaging Using Europium Chelate Luminescent Coatings
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High-resolution Thermal Micro-imaging Using Europium Chelate Luminescent Coatings

Published on: April 16, 2017

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不对称的稳定热开花不对称的热开花

Jeremiah Lane, Benjamin Akers, Jonah Reeger

    Applied optics
    |August 12, 2025
    PubMed
    概括

    这项研究使用计算流体动力学模型对图激光器的热开花进行了模拟. 模拟显示,封闭室中的边界效应会导致不对称的激光斑点,与实验观测结果相匹配.

    科学领域:

    • 光学和光子学 在光学和光子学.
    • 计算流体动力学的流体动力学.
    • 激光物理 激光物理

    背景情况:

    • 热开花,激光诱导的加热改变介质的折射率的现象,影响激光束的传播.
    • 了解封闭环境中的热膨胀对于使用接近2微米的激光器的应用至关重要.

    研究的目的:

    • 在一个封闭的室内数值建模和研究一个图激光器的热开花.
    • 为了解释激光束形状中观察到的不对称性.

    主要方法:

    • 采用了用于激光传播的对轴方程,加上Navier-Stokes方程在浮力效应的Boussinesq近似下.
    • 采用辐射基函数 (RBF) 进行空间分离,并采用混合的帕德-牛顿方法来解决非线性方程.
    • 对实验数据进行验证的数值模拟.

    主要成果:

    • 数值模型成功地复制了热开花的实验观测.
    • 模拟表明,腔室的边界显著影响对流的流动模式.
    • 这种影响被确定为不对称的激光点形状的原因.

    结论:

    • 这项研究提供了一个验证的数值框架,用于分析狭小空间中的激光热开花.

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  • 这些发现强调了边界条件在决定光束扭曲方面的关键作用.
  • 这项研究有助于精确控制和应用图激光器.