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Mechanical Engineering動壓动压（英语：dynamic pressure）是一个与流体力学有关的物理量，其定义为： q ≡ 1 2 ρ v 2 {\displaystyle q\equiv {\frac {1}{2}}\rho {{v}^{2}}} 其中的符号代表（使用国际单位制）：
In fluid dynamics, dynamic pressure (denoted by q or Q and sometimes called velocity pressure) is the quantity defined by: q = 1 2 ρ u 2 {\displaystyle q={\frac {1}{2}}\rho \,u^{2}} where (in SI units): q is the dynamic pressure in pascals (i.e., N/m2), ρ (Greek letter rho) is the fluid mass density (e.g. in kg/m3), and u is the flow speed in m/s. It can be thought of as the fluid's kinetic energy per unit volume. For incompressible flow, the dynamic pressure of a fluid is the difference between its total pressure and static pressure.
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Wikipedia contributors · Retrieved2026-10-04 · CC BY-SA 4.0. Introductions were extracted as plain text and shortened. Language versions may emphasize different aspects.For concept reference; consult the original standards for authoritative requirements.
View content license ↗ 马赫（M或Ma，英语：Mach number）是流体力学中的无量纲数，表示通过边界的流速与局部音速之比。 M = u c {\displaystyle \mathrm {M} ={\frac {u}{c}}} ， 其中： M为局部马赫数， u为相对于边界的局部流速， c为介质中的音速。 马赫数的命名是为了纪念奥地利学者恩斯特·马赫（德语：Ernst Mach）。 马赫一般用于飞机、火箭等航空航天飞行器。由于声音在空气中的传播速度随着不同的条件而不同，因此马赫也只是一个相对的单位，每“一马赫”的具体速度并不固定。在低温下声音的传播速度低些，一马赫对应的具体速度也就低一些。因此相对来说，在高空比在低空更容易达到较高的马赫数。 1947年10月14日，查克·叶格驾驶X-1试验飞机在加州南部上空脱离B-29母机，上升到一万二千米高空，并在此高度上达到每小时1078公里的速度，首次突破音障，超过了一马赫。 当马赫数Ma<0.3时，流体所受的压力不足以压缩流体，仅会造成流体的流动。在此状况下，流体密度不会随压力而改变，此种流场称为亚音速流（Subsonic flow），流场可视为不可压缩流场。一般的水流及大气中空气的流动，譬如湍急的河流、台风风场和汽车的运动等，皆属于不可压缩流场。但流体在高速运动（流速接近音速或大于音速）时，流体密度会随压力而改变，此时气体之流动称为可压缩流场（Compressible flow）。当马赫数Ma>1.0，称为超音速流（Supersonic flow），此类流况在航空动力学中才会遇到。 任何超过音速移动的物体会从头部向后产生锥状的能量激波（速度越高锥角越小），其力量可能会破坏接触物体，而且会摩擦制造高温，因此其体型设计必须尽量限制在锥状激波的范围内，同时要采用高抗热性的材料。 在地表的速度换算相当于一马赫≈1235km/h，340m/s。飞行物在相同的速度下，其马赫会因所在高度空气的音速不同而有差异；高度越高，音速越低，而使得马赫越高，因此高空飞行的速度会降低以免产生冲击。
The Mach number (M or Ma), often only Mach (; German: [max]), is a dimensionless quantity in fluid dynamics representing the ratio of flow velocity past a boundary to the local speed of sound. It is named after Austrian physicist and philosopher Ernst Mach. M = u c , {\displaystyle \mathrm {M} ={\frac {u}{c}},} where: M is the local Mach number, u is the local flow velocity with respect to the boundaries (either internal, such as an object immersed in the flow, or external, like a channel), and c is the speed of sound in the medium, which in air varies with the square root of the thermodynamic temperature. By definition, at Mach 1, the local flow velocity u is equal to the speed of sound. At Mach 0.65, u is 65% of the speed of sound (subsonic), and, at Mach 1.35, u is 35% faster than the speed of sound (supersonic). The local speed of sound, and hence the Mach number, depends on the temperature of the surrounding gas.
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View content license ↗ 声速（英语：Speed of sound），指声波在介质中传递的速率，定义为声波在单位时间内所行进的路径长。
The speed of sound is the distance travelled per unit of time by a sound wave as it propagates through an elastic medium. More simply, the speed of sound is how fast vibrations travel. At 20 °C (68 °F), the speed of sound in air is about 343 m/s (1,125 ft/s; 1,235 km/h; 767 mph; 667 kn), or 1 km in 2.92 s or one mile in 4.69 s. It depends strongly on temperature as well as the medium through which a sound wave is propagating. At 0 °C (32 °F), the speed of sound in dry air (sea level 14.7 psi) is about 331 m/s (1,086 ft/s; 1,192 km/h; 740 mph; 643 kn). The speed of sound in an ideal gas depends only on its temperature and composition. The speed has a weak dependence on frequency and pressure in dry air, deviating slightly from ideal behavior. In colloquial speech, speed of sound refers to the speed of sound waves in air. The speed of sound varies from substance to substance, however: typically, sound travels most slowly in gases, faster in liquids, and fastest in solids.
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View content license ↗ 阻流（Choked flow）也称为阻塞流，是流体动力学中，在可压缩流中的效应，其中的流体速度受到限制（受到阻塞），和文丘里效应效应有关。当特定压力及温度的流体经过管路突缩位置（例如拉伐尔喷管的喉部或是管路的阀门）到压力较低的环境下，其流体速度会增加。依初始在上游的次音速条件，依照质量守恒定律，流体在经过截面积较小的管路突缩位置时，其速度要增加。同时因为文丘里效应，在管路突缩位置的静压（以及对应密度）都要降低。若在上游压力及温度固定时，即使下游的压力降低，其质量流率也不再增加，此时的情形即称为阻塞流。 针对均质流体，在绝热过程下会发生阻塞流的情形，需要出口平面的速度到达音速时才会出现，也就是马赫数为1。在阻塞流时，只有增加上游流体的密度（以及阻塞点的流体密度）才能增加质量流率。 气体阻塞流的的质量流率和下游的压力无关，只和上游的温度及压力（及密度）有关，因此常用在许多工程应用中。在阻塞流的条件下，可以用阀或是校正过的孔口板来产生想要质量流率。
Choked flow is a compressible flow effect. The parameter that becomes "choked" or "limited" is the fluid velocity. Choked flow is a fluid dynamic condition associated with the Venturi effect. When a flowing fluid at a given pressure and temperature passes through a constriction (such as the throat of a convergent-divergent nozzle or a valve in a pipe) into a lower pressure environment the fluid velocity increases. At initially subsonic upstream conditions, the conservation of energy principle requires the fluid velocity to increase as it flows through the smaller cross-sectional area of the constriction. At the same time, the Venturi effect causes the static pressure, and therefore the density, to decrease at the constriction. Choked flow is a limiting condition where the mass flow cannot increase with a further decrease in the downstream pressure environment for a fixed upstream pressure and temperature.
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View content license ↗ 激波（英语：Shock Wave），又译作冲击波、骇波或激波，属于紊流的一种传播形式。如同其他通常形式下的波动，激波也可以通过介质传输能量。在某些不存在物理介质的特殊情况下，激波可以通过场，如电磁场来传输能量。激波的主要特点表现为介质特性（如压力、温度、或速度）在激波前后发生了一个像正的阶梯函数般的突然变化。与此相应的负的阶跃则为膨胀波。声学激波其速度一般高于通常波速（在空气中即音速）。 激波随距离的增加耗散很快，与孤波（另一种形式的非线性波）不同。而且，膨胀波总是伴随着激波，并最终与激波合并。这部分抵消了激波的影响。声爆，一种超音速飞机通过时产生的声学现象，即是由激波——膨胀波对激波的耗散和湮灭所产生的。
In mechanics, specifically acoustics, a shock wave, shockwave, or shock is a type of propagating disturbance that moves faster than the local speed of sound in the medium. Like an ordinary wave, a shock wave carries energy and can propagate through a medium, but is characterized by an abrupt, nearly discontinuous, change in pressure, temperature, and density of the medium. For the purpose of comparison, in supersonic flows, additional increased expansion may be achieved through an expansion fan, also known as a Prandtl–Meyer expansion fan. The accompanying expansion wave may approach and eventually collide and recombine with the shock wave, creating a process of destructive interference. The sonic boom associated with the passage of a supersonic aircraft is a type of sound wave produced by constructive interference. Unlike solitons (another kind of nonlinear wave), the energy and speed of a shock wave alone dissipates relatively quickly with distance. When a shock wave passes through matter, energy is preserved but entropy increases.
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View content license ↗ 在空气动力学中，升阻比（L/D）是指飞行器在同一迎角下升力与阻力的比值。飞行器的升阻比越大，其空气动力性能越好，对飞行越有利，也会有较佳爬升性能。升阻比的公式如下 L / D = L F D {\displaystyle L/D={L \over F_{D}}} 其中L为升力， F D {\displaystyle F_{D}} 为阻力。
In aerodynamics, the lift-to-drag ratio (or L/D ratio) is the lift generated by an aerodynamic body such as an aerofoil or aircraft, divided by the aerodynamic drag caused by moving through air. It describes the aerodynamic efficiency under given flight conditions. The L/D ratio for any given body will vary according to these flight conditions. For an aerofoil wing or powered aircraft, the L/D is specified when in straight and level flight. For a glider it determines the glide ratio, of distance travelled against loss of height. The term is calculated for any particular airspeed by measuring the lift generated, then dividing by the drag at that speed. These vary with speed, so the results are typically plotted on a 2-dimensional graph. In almost all cases the graph forms a U-shape, due to the two main components of drag. The L/D may be calculated using computational fluid dynamics or computer simulation. It is measured empirically by testing in a wind tunnel or in free flight test.
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View content license ↗ 阻力（英语：Drag），又称后曳力或流体阻力，是物体在流体动力学中相对运动所产生与运动方向相反的力。 对于一个在流体中移动的物体，阻力为周围流体对物体施力，在移动方向的反方向上分量的总和。而施力和移动方向垂直的分量一般则视为升力。因此阻力和物体移动方向恰好相反，像飞机前进时会产生推力来克服阻力的影响。 在航天动力学中，大气阻力可以视为太空飞行器在发射时的低效率，其影响则是在发射时需要额外的能量，不过在返回轨道时大气阻力有助于太空飞行器减速，可减少减速额外需要的能量，不过大气阻力产生的热量甚至可以将物体熔化。
In fluid dynamics, drag, sometimes referred to as fluid resistance, and also known as viscous force, is a force acting opposite to the direction of motion of any object moving with respect to a surrounding fluid. This can exist between two fluid layers, or between a fluid and a solid surface. Drag forces tend to decrease fluid velocity relative to the solid object in the fluid's path. Unlike other resistive forces, drag force depends on velocity. Drag force is proportional to the relative velocity for low-speed flow and is proportional to the velocity squared for high-speed flow. This distinction between low and high-speed flow is measured by the Reynolds number.
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View content license ↗ 辐射冷却是指物件透过辐射散去热能的过程。 在气象学上，地球表面所吸收的太阳热能，到了夜晚会向天空发射出长波辐射，如果夜间天气晴朗、微风及干燥的情况下，地表的温度会快速冷却，产生突然降到低温的情形，就是所谓的“辐射冷却效应”。在日间时，地面吸收来自太阳热能的速度比散发的快，因此气温就会上升；到了夜晚，地面吸收来自太阳热能的速度比散发的慢，气温就会下降。另外，云层会阻隔辐射冷却，空气中的水分会阻挡地面的热能向外散发，因此部分天气晴朗以及干燥的地方，夜间温度下降的速度会特别快。
In the study of heat transfer, radiative cooling is the process by which a body loses heat by thermal radiation. As Planck's law describes, every physical body spontaneously and continuously emits electromagnetic radiation. Radiative cooling has been applied in various contexts throughout human history, including ice making in India and Iran, heat shields for spacecraft, and in architecture. In 2014, a scientific breakthrough in the use of photonic metamaterials made daytime radiative cooling possible. It has since been proposed as a strategy to mitigate local and global warming caused by greenhouse gas emissions known as passive daytime radiative cooling.
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View content license ↗ 黑体辐射指处于热力学平衡态的黑体发出的电磁辐射。黑体辐射的电磁波谱只取决于黑体的温度。另一方面，所谓黑体辐射是光和物质达到平衡所表现出的现象。物质达到平衡，所以可以用一个温度来描述物质的状态，而光和物质的交互作用很强，如此光和光之间也可以用一个温度来描述（光和光之间本身不会有交互作用，但光和物质的交互作用很强），而描述这关系的便是普朗克分布（Planck distribution）。黑体辐射能量按波长的分布仅与温度有关。 黑体不仅仅能全部吸收外来的电磁辐射，且散射电磁辐射的能力比同温度下的任何其它物体强。对于黑体的研究，使自然现象中的量子效应被发现。而黑体作为一个理想化的物体，在现实中是不存在的，因此现实中物体的辐射也与理论上的黑体辐射有所出入。但是，可以观察一些非常类似黑体的物质发出的辐射，例如一颗恒星或一个只有单一开口的空腔所发出的辐射。举个例来说，人们观测到宇宙背景辐射，对应到一个约3K的黑体辐射，这暗示宇宙早期光是和物质达到平衡的。而随着时间演化，温度慢慢降了下来，但方程式依然存在。（频率和温度的效应抵销）
Black-body radiation is the thermal electromagnetic radiation emitted from a body in thermodynamic equilibrium with its environment. A black body is an idealized opaque and non-reflective body. The radiation emitted is a continuous spectrum over all possible radiation wavelengths that depends only on the body's temperature. A perfectly-insulated enclosure which is in thermal equilibrium internally contains black-body radiation and will emit it through a hole made in its wall, provided the hole is small enough to have a negligible effect upon the equilibrium. The thermal radiation spontaneously emitted by many ordinary objects can be approximated as black-body radiation. Of particular importance, although planets and stars (including the Earth and Sun) are neither in thermal equilibrium with their surroundings nor perfect black bodies, black-body radiation is still a good first approximation for the energy they emit.
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View content license ↗ 热惰性（thermal inertia），也称为热惯量，常用于描述在传热过程中观测到的物体温度响应延迟。该现象产生于物体相对于其环境既能存储热量又能传输热量的能力。由于系统组分的构型与传热方式（例如传导、对流、辐射、相变）以及能量存储形式（例如内能、焓、潜热）在不同实例间差异显著，因此不存在对热惰性具有普适适用性的封闭形式数学表达式。 具有较大质量和热容量的实体通常表现出较慢的温度响应。然而，仅以热容量来量化热惰性并不充分。对热惰性的测量还取决于热流在体内与体外的分布情况，需根据系统的边值问题予以判断。 热惰性是内含及外延性质取决于语境。一些作者将其作为一种材料的强度性属性来识别，例如与热逸散率相关联时。也有人根据系统在瞬态传热过程中的时空行为对其作为外延量进行评价。在这种基于测量或数值模拟的空间—时间行为分析中，有时可用一个时间常数作为所选组件或子系统热惰性的简单参数化表示。
Thermal inertia is a term commonly used to describe the observed delays in a body's temperature response during heat transfers. The phenomenon exists because of a body's ability to both store and transport heat relative to its environment. Since the configuration of system components and modes of transport (e.g. conduction, convection, radiation, phase change) and energy storage (e.g. internal energy, enthalpy, latent heat) vary substantially between instances, there is no generally applicable mathematical expression of closed form for thermal inertia. Bodies with relatively large mass and heat capacity typically exhibit slower temperature responses. However heat capacity alone cannot accurately quantify thermal inertia. Measurements of it further depend on how heat flows are distributed inside and outside a body, in accordance with system boundary conditions. Whether thermal inertia is an intensive or extensive quantity depends upon context. Some authors have identified it as an intensive material property, for example in association with thermal effusivity.
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View content license ↗ 晶体通常可分为七种晶系，即立方晶系、六方晶系、四方晶系、三方晶系、正交晶系、单斜晶系、三斜晶系。其中的立方晶系具有各向同性，属于高级晶族。
In crystallography, a crystal system is a set of point groups (a group of geometric symmetries with at least one fixed point). A lattice system is a set of Bravais lattices (an infinite array of discrete points). Space groups (symmetry groups of a configuration in space) are classified into crystal systems according to their point groups, and into lattice systems according to their Bravais lattices. Crystal systems that have space groups assigned to a common lattice system are combined into a crystal family. Informally, two crystals are in the same crystal system if they have similar symmetries (though there are many exceptions).
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View content license ↗ 晶体生长(英语：Crystal growth)是物质结晶过程中，继成核之后进行的一个重要阶段。宏观上，晶体生长过程是晶体——环境相(蒸气、溶液、熔体) 界面向环境相中不断推进的过程，即晶核超过临界大小之后，由包含组成晶体单元的母相从低有序相向高有序晶相的转变。晶体被定义为原子，分子或离子以有序的重复模式排列，晶格在所有三个空间维度上延伸。 因此，晶体生长不同于液滴生长，因为在生长过程中，分子或离子必须落入正确的晶格位置，以便有序的晶体生长。
Crystal growth is a major stage of a crystallization process, and consists of the addition of new atoms, ions, or polymer strings into the characteristic arrangement of the crystalline lattice. The growth typically follows an initial stage of either homogeneous or heterogeneous (surface catalyzed) nucleation, unless a "seed" crystal, purposely added to start the growth, was already present. The action of crystal growth yields a crystalline solid whose atoms or molecules are close packed, with fixed positions in space relative to each other. The crystalline state of matter is characterized by a distinct structural rigidity and very high resistance to deformation (i.e. changes of shape and/or volume). Most crystalline solids have high values both of Young's modulus and of the shear modulus of elasticity.
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View content license ↗ 不确定性量化（UQ）是对计算和现实世界应用中的不确定性进行定量表征和估计的科学。它试图确定如果系统的某些方面不完全已知的话某些结果的可能性有多大。一个例子是预测人体与另一辆车正面相撞时的加速度：即使速度是准确已知的，个别汽车制造过程中的微小差异、每个螺栓的拧紧程度等都会导致不同的结果，而这些结果只能在统计意义上进行预测。自然科学和工程学中的许多问题也充满了不确定性。计算机模拟的计算机实验是研究不确定性量化问题的最常见方法。
Uncertainty Quantification (UQ) is the science of quantitative characterization and estimation of uncertainties in both computational and real world applications. It tries to determine how likely certain outcomes are if some aspects of the system are not exactly known. An example would be to predict the acceleration of a human body in a head-on crash with another car: even if the speed was exactly known, small differences in the manufacturing of individual cars, how tightly every bolt has been tightened, etc., will lead to different results that can only be predicted in a statistical sense. Many problems in the natural sciences and engineering are also rife with sources of uncertainty. Computer experiments on computer simulations are the most common approach to study problems in uncertainty quantification.
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View content license ↗ 在概率论与统计学中，协方差（英语：Covariance）用于衡量随机变量间的相关程度。
In probability theory and statistics, covariance is a measure of the joint variability of two random variables. The sign of the covariance shows the tendency in the linear relationship between the variables. Covariance is positive when variables tend to show similar behavior and negative when variables tend to show opposite behavior. The magnitude of the covariance is the geometric mean of the variances that are shared for the two random variables, where a larger magnitude means two variables more strongly depend on each other. Covariance has units of measurement, and the magnitude of the covariance is affected by said units. This means changing the units (e.g., from meters to millimeters) changes the covariance value proportionally, making it difficult to assess the strength of the relationship from the covariance alone.
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Wikipedia contributors · Retrieved2026-10-04 · CC BY-SA 4.0. Introductions were extracted as plain text and shortened. Language versions may emphasize different aspects.For concept reference; consult the original standards for authoritative requirements.
View content license ↗ 卡尔曼滤波（英语：Kalman filter）是一种高效率的递归滤波器（自回归滤波器），它能够从一系列的不完全及包含噪声的测量中，估计动态系统的状态。卡尔曼滤波会根据各测量量在不同时间下的值，考虑各时间下的联合分布，再产生对未知变量的估计，因此会比只以单一测量量为基础的估计方式要准。卡尔曼滤波得名自主要贡献者之一的鲁道夫·卡尔曼。 卡尔曼滤波在技术领域有许多的应用。常见的有飞机及太空船的导引、导航及控制。卡尔曼滤波也广为使用在时间序列的分析中，例如信号处理及计量经济学中。卡尔曼滤波也是机器人运动规划及控制的重要主题之一，有时也包括在轨迹优化。卡尔曼滤波也用在中轴神经系统运动控制的建模中。因为从给与运动命令到收到感觉神经的回授之间有时间差，使用卡尔曼滤波有助于建立符合实际的系统，估计运动系统的目前状态，并且更新命令。 卡尔曼滤波的算法是二步骤的程序。在估计步骤中，卡尔曼滤波会产生有关目前状态的估计，其中也包括不确定性。只要观察到下一个量测（其中一定含有某种程度的误差，包括随机噪声）。会通过加权平均来更新估计值，而确定性越高的量测加权比重也越高。算法是迭代的，可以在实时控制系统中执行，只需要目前的输入量测、以往的计算值以及其不确定性矩阵，不需要其他以往的信息。 使用卡尔曼滤波不用假设误差是正态分布，不过若所有的误差都是正态分布，卡尔曼滤波可以得到正确的条件概率估计。 也发展了一些扩展或是广义的卡尔曼滤波，例如运作在非线性系统的扩展卡尔曼滤波及无迹卡尔曼滤波（英语：unscented Kalman filter）。底层的模型类似隐马尔可夫模型，不过潜在变量的状态空间是连续的，而且所有潜在变量及可观测变量都是正态分布。
In statistics and control theory, Kalman filtering (also known as linear quadratic estimation) is an algorithm that uses a series of measurements observed over time, including statistical noise and other inaccuracies, to produce estimates of unknown variables that tend to be more accurate than those based on a single measurement, by estimating a joint probability distribution over the variables for each time-step. The filter is constructed as a mean squared error minimiser, but also relates to maximum likelihood statistics. The filter is named after Rudolf E. Kálmán. Kalman filtering has numerous technological applications. A common application is for guidance, navigation, and control of vehicles, particularly aircraft, spacecraft and ships positioned dynamically. Furthermore, Kalman filtering is much applied in time series analysis tasks such as signal processing and econometrics. Kalman filtering is also important for robotic motion planning and control, and can be used for trajectory optimization.
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Wikipedia contributors · Retrieved2026-10-04 · CC BY-SA 4.0. Introductions were extracted as plain text and shortened. Language versions may emphasize different aspects.For concept reference; consult the original standards for authoritative requirements.
View content license ↗ 反馈（英语：feedback，台湾作回馈），又称回授，是控制论的基本概念，指将系统的输出返回到输入端并以某种方式改变输入，它们之间存在因果关系的回路，进而影响系统功能的过程。在这种情况下，我们可以说系统“反馈到它自身”。在讨论反馈系统时，因果关系的概念应当特别仔细对待： “对于反馈系统，很难作出简单的推理归因，因为当系统A反馈到系统B，系统B又反馈到系统A，形成了循环。这使得基于因果关系的分析特别困难，需要将系统作为一个整体来看待。” 反馈可分为负反馈和正反馈。前者使输出发挥与输入相反的作用，使系统输出与系统目标的误差减少，系统趋于稳定；后者使输出发挥与输入相似的作用，使系统偏差不断增加，使系统振荡，可以放大控制作用。对负反馈的研究是控制论的核心问题。
Feedback occurs when outputs of a system are routed back as inputs as part of a chain of cause and effect that forms a circuit or loop. The system can then be said to feed back into itself. The notion of cause-and-effect has to be handled carefully when applied to feedback systems: Simple causal reasoning about a feedback system is difficult because the first system influences the second and second system influences the first, leading to a circular argument. This makes reasoning based upon cause and effect tricky, and it is necessary to analyze the system as a whole. As provided by Webster, feedback in business is the transmission of evaluative or corrective information about an action, event, or process to the original or controlling source.
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Wikipedia contributors · Retrieved2026-10-04 · CC BY-SA 4.0. Introductions were extracted as plain text and shortened. Language versions may emphasize different aspects.For concept reference; consult the original standards for authoritative requirements.
View content license ↗ 在工程中，传递函数（英语：transfer function，也称系统函数、转移函数或网络函数，画出的曲线叫做传递曲线）是用来拟合或描述黑箱模型（系统）的输入与输出之间关系的数学表示。在二维图像的应用中，输入和输出的位图间的关系函数称作转移曲线、转换曲线（transfer curve）或特征曲线（characteristic curve）。 通常它是零初始条件和零平衡点下，以空间或时间频率为变量表示的线性时不变系统（LTI）的输入与输出之间的关系。然而一些资料来源中用“传递函数”直接表示某些物理量输入输出的特性，（例如二端口网络中的输出电压作为输入电压的一个函数）而不使用变换到S平面上的结果。
In engineering, a transfer function (also known as system function or network function) of a system, sub-system, or component is a mathematical function that models the system's output for each possible input. It is widely used in electronic engineering tools like circuit simulators and control systems and in chemical reaction engineering for the study and modeling of the residence time distribution and stability of a reactor. In simple cases, this function can be represented as a two-dimensional graph of an independent scalar input versus the dependent scalar output (known as a transfer curve or characteristic curve). Transfer functions for components are used to design and analyze systems assembled from components, particularly using the block diagram technique, in electronics and control theory. Dimensions and units of the transfer function model the output response of the device for a range of possible inputs.
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Wikipedia contributors · Retrieved2026-10-04 · CC BY-SA 4.0. Introductions were extracted as plain text and shortened. Language versions may emphasize different aspects.For concept reference; consult the original standards for authoritative requirements.
View content license ↗ PID控制器（比例-积分-微分控制器），由比例单元（Proportional）、积分单元（Integral）和微分单元（Derivative）组成。可以透过调整这三个单元的增益 K p {\displaystyle K_{p}} ， K i {\displaystyle K_{i}} 和 K d {\displaystyle K_{d}} 来调定其特性。PID控制器主要适用于基本上线性，且动态特性不随时间变化的系统。 PID控制器是一个在工业控制应用中常见的回授回路部件。这个控制器把收集到的数据和一个参考值进行比较，然后把这个差别用于计算新的输入值，这个新的输入值的目的是可以让系统的数据达到或者保持在参考值。PID控制器可以根据历史数据和差别的出现率来调整输入值，使系统更加准确而稳定。 PID控制器的比例单元（P）、积分单元（I）和微分单元（D）分别对应目前误差、过去累计误差及未来误差。若是不知道受控系统的特性，一般认为PID控制器是最适用的控制器。借由调整PID控制器的三个参数，可以调整控制系统，设法满足设计需求。控制器的响应可以用控制器对误差的反应快慢、控制器过冲的程度及系统震荡的程度来表示。不过使用PID控制器不一定保证可达到系统的最佳控制，也不保证系统稳定性。 有些应用只需要PID控制器的部分单元，可以将不需要单元的参数设为零即可。因此PID控制器可以变成PI控制器、PD控制器、P控制器或I控制器。其中又以PI控制器比较常用，因为D控制器对回授噪声十分敏感，而若没有I控制器的话，系统不会回到参考值，会存在一个误差量。
A proportional–integral–derivative (PID) controller, or three-term controller, is a feedback-based control loop mechanism commonly used to manage machines and processes that require continuous control and automatic adjustment. It is typically used in industrial control systems and various other applications where constant control through modulation is necessary without human intervention. The PID controller automatically compares the desired target value (setpoint or SP) with the actual value of the system (process variable or PV). The difference between these two values is called the error value, denoted as e ( t ) {\displaystyle e(t)} . It then applies corrective actions automatically to bring the PV to the same value as the SP using three methods: The proportional (P) component responds to the current error value by producing an output that is directly proportional to the magnitude of the error. This provides immediate correction based on how far the system is from the desired setpoint.
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Wikipedia contributors · Retrieved2026-10-04 · CC BY-SA 4.0. Introductions were extracted as plain text and shortened. Language versions may emphasize different aspects.For concept reference; consult the original standards for authoritative requirements.
View content license ↗ 传感器（英语：Sensor）是一种检测环境中的事件或变化，并将此信息传送至其他电子设备（如中央处理器）的设备，通常由敏感器件和转换器件组成。传感器如被动式红外传感器和触摸传感器已广泛应用于日常物品，如触摸感应的电梯按钮和调光灯，以及温度、压力和流量测量等传统领域之外的无数应用中。随着微机电系统（MEMS）技术的进步，传感器可在微观尺度上批量制造，达到更快的测量速度和更高的灵敏度。一次性传感器的需求也在增长，用于短期监测或单次测量，无需重新校准且避免交叉污染。
A sensor is often defined as a device that receives and responds to a signal or stimulus. The stimulus is the quantity, property, or condition that is sensed and converted into electrical signal. In the broadest definition, a sensor is a device, module, machine, or subsystem that detects events or changes in its environment and sends the information to other electronics, frequently a computer processor. Sensors like PIR sensor or touch sensor are used in everyday objects such as touch-sensitive elevator buttons (tactile sensor) and lamps which dim or brighten by touching the base, and in innumerable applications of which most people are never aware. With advances in micromachinery and easy-to-use microcontroller platforms, the uses of sensors have expanded beyond the traditional fields of temperature, pressure and flow measurement, for example into MARG sensors. Analog sensors such as potentiometers and force-sensing resistors are still widely used.
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Wikipedia contributors · Retrieved2026-10-04 · CC BY-SA 4.0. Introductions were extracted as plain text and shortened. Language versions may emphasize different aspects.For concept reference; consult the original standards for authoritative requirements.
View content license ↗ 标定（英语：Calibration），即为科学上之校准行为，意指“对某仪器、药物或须有精确单位之物品，其只知的体积、浓度......等刻度或单位之准确度，进行检测是否合乎标准，若否则修正。”
In measurement technology and metrology, calibration is the comparison of measurement values delivered by a device under test with those of a calibration standard of known accuracy. Such a standard could be another measurement device of known accuracy, a device generating the quantity to be measured such as a voltage, a sound tone, or a physical artifact, such as a meter ruler. The outcome of the comparison can result in one of the following: no significant error being noted on the device under test a significant error being noted but no adjustment made an adjustment made to correct the error to an acceptable level Strictly speaking, the term "calibration" means just the act of comparison and does not include any subsequent adjustment. The calibration standard is normally traceable to a national or international standard held by a metrology body.
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Wikipedia contributors · Retrieved2026-10-04 · CC BY-SA 4.0. Introductions were extracted as plain text and shortened. Language versions may emphasize different aspects.For concept reference; consult the original standards for authoritative requirements.
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