📚 A-Level WJEC Engineering: Vocabulary and Terminology Quick Reference Guide | A-Level WJEC 工程：词汇术语速记指南
This quick-reference guide covers the essential vocabulary across all key topics in the WJEC A-Level Engineering syllabus. Mastering these terms will give you the precision and confidence needed to tackle definitions, calculations, and design questions effectively.
本快速参考指南涵盖了 WJEC A-Level 工程课程所有关键部分的核心词汇。熟练掌握这些术语将帮助您精准、自信地应对定义题、计算题和设计题。
1. Materials and Properties | 材料与特性
Stress: The internal force per unit area within a material, measured in Pascals (Pa).
应力：材料内部单位面积上的内力，单位为帕斯卡 (Pa)。
Strain: The deformation per unit length; it is dimensionless and often expressed as a percentage.
应变：每单位长度的变形量，无量纲，常以百分比表示。
Young’s Modulus: The ratio of stress to strain in the linear-elastic region, representing a material’s stiffness.
杨氏模量：线弹性区域内应力与应变的比值，衡量材料的刚度。
Toughness: The ability of a material to absorb energy up to fracture, corresponding to the area under the stress-strain curve.
韧性：材料断裂前吸收能量的能力，对应应力-应变曲线下方的面积。
Hardness: Resistance to surface indentation or scratching, often measured by Brinell or Rockwell tests.
硬度：抵抗表面压入或划伤的能力，常通过布氏或洛氏硬度试验测量。
2. Mechanical Principles | 力学原理
Moment of a Force: The turning effect about a pivot, calculated as the product of the force and the perpendicular distance from the pivot.
力矩：力绕支点产生的转动效应，大小等于力与支点垂直距离的乘积。
Mechanical Advantage (MA): The ratio of output force (load) to input force (effort) in a mechanism.
机械效益 (MA)：机构中输出力（负载）与输入力（动力）之比。
Velocity Ratio (VR): The ratio of the distance moved by the effort to the distance moved by the load in the same time.
速度比 (VR)：相同时间内动力移动的距离与负载移动的距离之比。
Efficiency: The percentage of input power that is converted into useful output power: (useful output power / input power) × 100%.
效率：输入功率转化为有用输出功率的百分比：(有用输出功率 / 输入功率) × 100%.
3. Electronics and Circuits | 电子与电路
Ohm’s Law: The relationship V = I × R, where V is voltage (volts), I is current (amperes), and R is resistance (ohms).
欧姆定律：关系式 V = I × R，其中 V 为电压（伏特），I 为电流（安培），R 为电阻（欧姆）。
Kirchhoff’s Current Law: At any junction in a circuit, the total current entering equals the total current leaving.
基尔霍夫电流定律：电路中任一节点处，流入的总电流等于流出的总电流。
Potential Divider: A simple circuit using two resistors in series to produce a fraction of the input voltage at their junction.
分压器：利用两个串联电阻在连接处获得输入电压一部分的简单电路。
Capacitance: The ability of a component to store electrical charge, measured in farads (F).
电容：元器件储存电荷的能力，单位为法拉 (F)。
4. Manufacturing Processes | 制造工艺
Casting: A process where molten metal is poured into a mould and allowed to solidify into a specific shape.
铸造：将熔融金属浇入模具中，使其凝固成特定形状的工艺。
Forging: Shaping metal using compressive forces, often at elevated temperatures, to refine its microstructure.
锻造：使用压缩力（常在高温下）使金属成形，以改善显微组织。
CNC Machining: Computer numerical control; automated machine tools are guided by coded instructions to cut material precisely.
CNC 加工：计算机数控；由编码指令引导的自动化机床精确切削材料。
Additive Manufacturing: Building a component layer by layer directly from a 3D model, e.g. fused deposition modelling (FDM).
增材制造：直接从三维模型逐层构建零件，例如熔融沉积成型 (FDM)。
5. Systems and Control | 系统与控制
Open-loop System: A control system that operates without feedback; the output is not compared with the desired value.
开环系统：无反馈运行的控制系统，输出不与期望值进行比较。
Closed-loop System: A system that continuously compares actual output with the desired input using feedback to minimise error.
闭环系统：利用反馈连续比较实际输出与期望输入以最小化误差的系统。
PID Controller: A proportional-integral-derivative controller that adjusts output based on the error magnitude, its accumulated history, and its rate of change.
PID 控制器：比例-积分-微分控制器，根据误差大小、累积历史和变化率调整输出。
Feedback: Returning a fraction of the output signal to the input to improve accuracy and stability.
反馈：将部分输出信号返回输入端以提高精度和稳定性。
6. Engineering Drawing and CAD | 工程图纸与 CAD
Orthographic Projection: A method of representing a 3D object using multiple 2D views, typically front, side, and top, aligned with projection planes.
正投影：利用多个二维视图表现三维物体的方法，通常为前视图、侧视图和顶视图，与投影平面对齐。
Tolerance: The permissible limit of variation in a dimension, specified to ensure parts fit together correctly.
公差：尺寸允许的变化范围，为确保零件正确配合而规定。
Sectional View: A drawing that reveals internal features by imagining the part is cut along a plane, with cut surfaces hatched.
剖视图：假设沿某一平面切开零件以显示内部特征，切割面带有剖面线。
Isometric Drawing: A pictorial projection where vertical lines remain vertical and horizontal lines are drawn at 30° to the horizontal, showing three faces simultaneously.
等角投影图：一种立体投影，垂直线保持垂直，水平线以与水平成 30° 角绘制，可同时显示三个面。
7. Fluid Mechanics | 流体力学
Pressure: The force exerted per unit area, P = F / A, measured in pascals (Pa).
压强：单位面积上施加的力，P = F / A，单位为帕斯卡 (Pa)。
Bernoulli’s Principle: For steady, incompressible, inviscid flow, an increase in fluid velocity occurs simultaneously with a decrease in pressure.
伯努利原理：对于定常、不可压缩、无粘流动，流体速度增加时压力随之减小。
Reynolds Number (Re): A dimensionless parameter that predicts whether flow will be laminar or turbulent, calculated as Re = ρvd/μ.
雷诺数 (Re)：预测流动是层流还是湍流的无量纲参数，计算公式为 Re = ρvd/μ。
Continuity Equation: For an incompressible fluid, the product of cross-sectional area and velocity is constant: A₁v₁ = A₂v₂.
连续性方程：对于不可压缩流体，截面积与速度的乘积保持恒定：A₁v₁ = A₂v₂。
8. Thermodynamics | 热力学
First Law of Thermodynamics: Energy is conserved; the change in internal energy of a system equals heat added minus work done, ΔU = Q – W.
热力学第一定律：能量守恒；系统内能的变化等于加入的热量减去系统对外做的功，ΔU = Q – W。
Specific Heat Capacity: The amount of energy required to raise the temperature of 1 kg of a substance by 1 K (or 1°C), in J/(kg·K).
比热容：使 1 kg 物质温度升高 1 K（或 1°C）所需的能量，单位为 J/(kg·K)。
Carnot Efficiency: The maximum theoretical efficiency of a heat engine operating between two reservoirs, η = 1 – T_cold / T_hot (in Kelvin).
卡诺效率：在两个热源之间工作的热机的最大理论效率，η = 1 – T_冷 / T_热（开尔文温度）。
Latent Heat: The energy absorbed or released during a phase change at constant temperature, e.g. latent heat of fusion.
潜热：恒温下相变过程中吸收或释放的能量，如熔化潜热。
9. Structures and Mechanics of Materials | 结构与材料力学
Bending Moment: The internal moment that causes a beam to bend; at a section it equals the algebraic sum of moments from external forces on one side.
弯矩：使梁发生弯曲的内部力矩；在某一截面处等于该截面一侧外力对该截面力矩的代数和。
Shear Force: The internal force acting parallel to the cross-section, resisting sliding of one part over the other.
剪切力：平行于截面作用的内部力，抵抗一部分相对于另一部分滑动。
Buckling: A sudden sideways deflection of a slender structural member when subjected to compressive stress, occurring well before material yield.
屈曲：细长构件在压缩应力下突然发生的侧向挠曲，在材料屈服前就出现。
Factor of Safety: The ratio of ultimate (or yield) stress to allowable working stress, providing a margin for uncertainties.
安全系数：极限应力（或屈服应力）与允许工作应力之比，为不确定因素提供安全裕度。
10. Mathematics and Units | 工程数学与单位
Scalar: A physical quantity that possesses magnitude only, such as mass, length, and energy.
标量：只有大小而没有方向的物理量，如质量、长度和能量。
Vector: A quantity that has both magnitude and direction, e.g. force, velocity, and displacement.
矢量：既有大小又有方向的量，例如力、速度和位移。
SI Base Units: metre (m), kilogram (kg), second (s), ampere (A), kelvin (K), mole (mol), candela (cd).
国际基本单位：米 (m)、千克 (kg)、秒 (s)、安培 (A)、开尔文 (K)、摩尔 (mol)、坎德拉 (cd)。
Derived Unit: Newton (N) = kg·m/s²; Joule (J) = N·m; Pascal (Pa) = N/m².
导出单位：牛顿 (N) = kg·m/s²；焦耳 (J) = N·m；帕斯卡 (Pa) = N/m²。
11. Communications and Standards | 通信与标准
BS 8888: The British standard for technical product documentation, covering drawing conventions, dimensions, and tolerances.
BS 8888：英国技术产品文件标准，涵盖工程图惯例、尺寸和公差。
Analogue Signal: A continuous signal that varies smoothly in amplitude and frequency, representing physical quantities like sound or temperature.
模拟信号：幅度和频率平滑变化的连续信号，代表声音或温度等物理量。
Digital Signal: A signal that takes only discrete levels (often binary 0 and 1), allowing noise-resistant transmission.
数字信号：仅取离散电平（常为二进制 0 和 1）的信号，可抗噪传输。
PWM (Pulse Width Modulation): A technique that controls average power delivered by varying the duty cycle of a square wave.
脉宽调制 (PWM)：通过改变方波的占空比来控制平均功率的技术。
12. Renewable Energy and Sustainability | 可再生能源与可持续性
Life Cycle Assessment (LCA): A systematic analysis of environmental impacts associated with all stages of a product’s life, from raw material extraction to disposal.
生命周期评估 (LCA)：对产品从原材料提取到处置的全生命周期各阶段环境影响进行系统分析。
Embodied Energy: The total primary energy consumed during the extraction, processing, manufacturing, and delivery of a material.
隐含能源：材料在提取、加工、制造和运输过程中消耗的一次能源总量。
Solar Photovoltaic Cell: A device that converts sunlight directly into electricity by the photovoltaic effect in semiconductors.
太阳能光伏电池：利用半导体中的光生伏打效应将阳光直接转化为电能的装置。
Betz Limit: The theoretical maximum efficiency of a wind turbine, approximately 59.3%, which cannot be exceeded regardless of design.
贝茨极限：风力发电机的理论最高效率，约 59.3%，无论设计如何均无法超越。
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