101 故障模式影响和临界分析（FMECA）

The Courant–Friedrichs–Lewy (CFL) condition is a necessary stability criterion for numerical solutions of hyperbolic partial differential equations using explicit time-integration schemes. It dictates that the time step size must be small enough that information does not travel further than one spatial grid cell per time step. For a 1D case, \(C = u \frac{\Delta t}{\Delta x} \le C_{max}\), ensuring numerical stability.

Pitting corrosion is a localized form of corrosion that leads to the creation of small holes, or 'pits,' in a metal. It is one of the most destructive forms because it is difficult to detect, predict, and design against. Pitting can cause catastrophic failure of a structure with only a small percentage of total mass loss.

The Finite Element Method (FEM) is a powerful numerical technique for solving complex engineering and physics problems described by partial differential equations. It works by discretizing a continuous domain into a set of smaller, simpler subdomains called 'finite elements'. This allows for the approximate numerical solution of problems in structural analysis, heat transfer, fluid flow, and electromagnetism.

FMEA is a systematic, bottom-up, inductive method for identifying potential failure modes in a system, product, or process. For each failure mode, it assesses the potential effects or consequences, their severity, likelihood of occurrence, and the ability to detect them. The goal is to prioritize and mitigate high-risk failure modes before they occur.

The marketing concept is a business philosophy holding that achieving organizational goals depends on knowing the needs and wants of target markets and delivering the desired satisfactions more effectively and efficiently than competitors. It represents a shift from a product-centric ("make and sell") approach to a customer-centric ("sense and respond") one, placing the customer at the core of all business decisions.

The reliability function, R(t), defines the probability that a system or component will perform its required function without failure for a specified time 't'. For systems with a constant failure rate (λ), it is described by the exponential distribution: \(R(t) = e^{-\lambda t}\). This function is fundamental to predicting the longevity and performance of a product.

The Deborah number is a dimensionless quantity in rheology, used to characterize the fluidity of materials. It is the ratio of the relaxation time, which is an intrinsic property of the material, to the characteristic time scale of the experiment or observation. The formula is \(De = \frac{t_c}{t_p}\), where \(t_c\) is the relaxation time and \(t_p\) is the observation time.

Thixotropy and rheopexy describe time-dependent changes in viscosity. A thixotropic fluid's viscosity decreases over time under constant shear stress (e.g., yogurt becomes runnier when stirred). A rheopectic (or anti-thixotropic) fluid's viscosity increases over time under constant shear (e.g., some lubricants). These effects are reversible; the fluid returns to its original state after a period of rest.

A non-Newtonian fluid is one whose viscosity changes under an applied shear stress. Unlike a Newtonian fluid where viscosity is constant, its flow properties are not described by a linear relationship between shear stress (\(\tau\)) and shear rate (\(\dot{gamma}\)). This dependency can manifest as shear-thinning (viscosity decreases with stress) or shear-thickening (viscosity increases with stress).

High-Efficiency Particulate Air (HEPA) and Ultra-Low Particulate Air (ULPA) filters are critical cleanroom components. A HEPA filter must remove at least 99.97% of airborne particles 0.3 micrometers (µm) in diameter. An ULPA filter is even more efficient, removing 99.999% of particles 0.12 µm or larger. They work via a combination of interception, impaction, and diffusion.

The Weissenberg effect is a phenomenon in viscoelastic fluids where the fluid climbs up a rotating rod inserted into it. This is contrary to the behavior of Newtonian fluids, which are pushed outwards by centrifugal force, forming a vortex. The effect is caused by normal stress differences that develop in the fluid under shear.

Plasticity is the theory describing the deformation of a solid material undergoing non-reversible changes of shape in response to applied forces. Unlike elasticity, where deformation is recovered upon unloading, plastic deformation is permanent. The theory involves a yield criterion to define the onset of plasticity, a flow rule to describe the evolution of plastic strain, and a hardening rule.

The PDCA cycle, also known as the Deming Cycle or Shewhart Cycle, is an iterative four-step management method used for the control and continuous improvement of processes and products. It provides a simple and effective approach for solving problems and managing change, ensuring that ideas are tested on a small scale before being implemented organization-wide.

The fundamental building block of modern digital electronics is the transistor, specifically the MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor). It operates as an electronically controlled switch. By applying a voltage to its gate terminal, the flow of current between its source and drain terminals can be turned on (representing a '1') or off (representing a '0'), enabling the implementation of logic gates.

A foundational model in marketing, the 4Ps framework classifies the key elements a business uses to promote its brand or product. It consists of Product (the item or service), Price (the cost to the consumer), Place (where it's sold), and Promotion (the advertising and sales activities). These four variables are controlled by the company to influence consumer demand.