氧乙炔火焰类型

Artificial gravity can be created in a spacecraft by rotating the structure. Occupants feel a centrifugal force pushing them towards the outer hull, mimicking gravity. The magnitude of this apparent gravity is given by [latex]a = \omega^2 r[/latex], where [latex]\omega[/latex] is the angular velocity and [latex]r[/latex] is the radius of rotation. This is proposed to counteract the negative health effects of long-term weightlessness.

Oxy-acetylene welding uses a flame produced by the combustion of acetylene ([latex]C_2H_2[/latex]) with pure oxygen. The reaction occurs in two stages. The primary reaction in the inner, white-hot cone is incomplete, producing carbon monoxide and hydrogen: [latex]2C_2H_2 + 2O_2 \rightarrow 4CO + 2H_2[/latex]. These hot gases then react with atmospheric oxygen in the outer envelope, completing the combustion.

TNT 的一个关键特性是其熔点低，仅为 80.6 °C (177.1 °F)，远低于其 240 °C 的自燃温度。如此大的温差使得 TNT 能够安全地用蒸汽或热水熔化，并浇铸到弹药外壳中，这一过程称为熔铸。这使得生产致密、均匀且无裂纹的炸药成为可能。

用于氧燃料焊接的气瓶储存气体或其他工业或医用气体，压力非常高。压力调节器对于将气体减压至安全可用的工作压力至关重要。两级调节器分两步进行减压，即使气瓶压力因使用而下降，也能提供高度恒定的输送压力。这确保了稳定的流量，从而产生稳定的火焰，确保焊接质量始终如一。

火灾三角是一个简单的模型，它描述了大多数火灾发生的三个基本要素：热量、燃料和氧化剂（通常是大气中的氧气）。消除其中任何一个要素，都可以阻止火灾发生或扑灭现有火灾。这是消防安全和预防的基本概念。

速度变化量（Δv），字面意思是“速度变化”，是衡量轨道机动所需冲量的标量。它量化了任务所需的总推进力，与航天器的质量无关。该值对于任务规划至关重要，因为它决定了所需的推进剂装载量。速度变化量是累积的；一次任务的总速度变化量是所有所需机动速度变化量的总和。

This equation describes the motion of vehicles that follow the basic principle of a rocket: a device that can apply acceleration to itself by expelling part of its mass with high velocity. It relates the delta-v a rocket can achieve to its effective exhaust velocity and the initial and final mass, given by [latex]\Delta v = v_e \ln \frac{m_0}{m_f}[/latex].

Oxy-fuel cutting, or flame cutting, severs ferrous metals by a rapid, exothermic oxidation process. First, a preheating flame raises the steel's surface to its kindling temperature (approx. 870 °C or 1600 °F). A high-pressure jet of pure oxygen is then directed at the spot, initiating a chemical reaction, [latex]3Fe + 2O_2 \rightarrow Fe_3O_4[/latex], which forms molten iron oxide (slag) and releases heat.

The separation factor, α (alpha), quantifies the selectivity of an extraction system for two different solutes, A and B. It is defined as the ratio of their individual distribution ratios, [latex]\alpha_{A,B} = \frac{D_A}{D_B}[/latex]. For a separation to be effective, α must be significantly different from unity. A larger α value implies an easier and more efficient separation.

The Log Mean Temperature Difference (LMTD) is the effective mean temperature difference for heat transfer in heat exchangers, particularly for counter-flow and parallel-flow arrangements. It is a logarithmic average of the temperature difference between the hot and cold fluids at each end. The LMTD is calculated using the formula: [latex]\Delta T_{LM} = \frac{\Delta T_A - \Delta T_B}{\ln(\Delta T_A / \Delta T_B)}[/latex].

回火脆化是指某些合金钢在特定温度范围内（约 375-575 °C）保温或缓慢冷却时，其韧性会降低。这种现象是由于杂质元素（例如磷、锡、锑）偏析至晶界，削弱了晶粒间的结合力，从而导致沿晶断裂。