Pulse-Echo Ultrasonic Testing

点状腐蚀是一种局部腐蚀，会在金属上形成小孔或 "凹坑"。点蚀是最具破坏性的腐蚀形式之一，因为它难以检测、预测和设计。点蚀只占总质量损失的一小部分，就能导致结构发生灾难性故障。

Liquid metal embrittlement is a phenomenon where a normally ductile solid metal experiences a severe loss of ductility and fails in a brittle manner when wetted by a specific liquid metal while under tensile stress. The failure is often catastrophic and rapid. The mechanism involves the liquid metal atoms adsorbing at a crack tip, which reduces the cohesive strength of the solid's atomic bonds.

准时制 (JIT) 是一种生产策略，旨在通过仅在生产过程中需要时接收货物来提高效率并减少浪费，从而降低库存成本。这种方法需要精准的预测和高度协调的供应链。目标是在正确的时间、正确的地点、以正确的数量获得正确的物料。

Freeze-drying, or lyophilization, is a dehydration process that leverages sublimation to preserve perishable materials. The material is first frozen, and then the surrounding pressure is reduced to allow the frozen water to sublime directly from the solid phase (ice) to the gas phase (water vapor). This avoids the damaging effects of heat-based drying methods.

FMEA 是一种系统性的、自下而上的归纳方法，用于识别系统、产品或流程中的潜在故障模式。对于每种故障模式，它会评估其潜在影响或后果、严重程度、发生的可能性以及检测能力。目标是在高风险故障模式发生之前确定其优先级并进行缓解。

PDCA循环，也称为戴明循环或休哈特循环，是一种迭代的四步管理方法，用于控制和持续改进流程和产品。它提供了一种简单有效的方法来解决问题和管理变革，确保想法在小范围内进行测试，然后再在整个组织范围内实施。

自働化（Jidoka）通常被翻译为“自动化”或“人性化的自动化”，是丰田生产系统的支柱之一。它授权任何机器或工人在检测到异常或缺陷时立即停止整条生产线。这可以防止大量生产缺陷产品，并立即发现问题，从而分析根本原因并找到永久性解决方案。

生产间隔时间（Takt time）是指为满足客户需求而生产产品所需的最长时间。它的计算方法是用净可用生产时间除以该时间段内的客户需求量。计算公式为：[latex]T = \frac{T_a}{D}[/latex]，其中，T 为工时，Ta 为净可用时间，D 为客户需求。

高效微粒空气 (HEPA) 过滤器和超低微粒空气 (ULPA) 过滤器是洁净室的关键组件。HEPA 过滤器必须能够去除至少 99.97% 直径为 0.3 微米 (µm) 的空气悬浮颗粒。ULPA 过滤器效率更高，能够去除 99.999% 直径为 0.12 µm 或更大的颗粒。它们通过拦截、撞击和扩散相结合的方式发挥作用。

A flashback is a dangerous condition where the flame propagates backward from the torch tip into the hoses. A flashback arrestor is a critical safety device that quenches this flame. It typically contains a flame-extinguishing element, such as a sintered metal filter, and a non-return valve to stop the reverse flow of gas, preventing explosive mixtures from forming in the hoses.

When an ultrasonic wave strikes the boundary between two different materials at an angle, it refracts, or changes direction. This is governed by Snell's Law, which relates the angles of incidence and refraction to the wave velocities in the two media: [latex]\frac{\sin\theta_1}{c_1} = \frac{\sin\theta_2}{c_2}[/latex]. This principle is fundamental for angle beam testing, used to inspect components like welds not accessible from directly above.

The Hollomon equation is an empirical power-law relationship that describes the portion of the true stress-true strain curve between the onset of plastic deformation (yielding) and the onset of necking (UTS). The equation is [latex]\sigma_t = K \epsilon_t^n[/latex], where [latex]\sigma_t[/latex] is the true stress, [latex]\epsilon_t[/latex] is the true plastic strain, K is the strength coefficient, and n is the strain-hardening exponent.

一个基本的经济事实是，企业对企业 (B2B) 交易的总金额远远超过企业对消费者 (B2C) 交易。这是因为一件成品消费品通常涉及一条漫长的供应链，包含多笔 B2B 交易——从原材料到制造部件，再到批发分销——最终在 B2C 销售之前完成。

看板在日语中意为“视觉卡片”或“招牌”，是丰田生产系统不可或缺的调度系统。它使用视觉提示（通常是卡片）来触发操作和管理工作流程。它是一种“拉动”系统，用于指示需要在制造工厂内部或从外部供应商处将物料运送到生产工厂。