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第1行： − 此词条暂由彩云小译翻译，翻译字数共3364，未经人工整理和审校，带来阅读不便，请见谅。+ + + 第5行：
第7行： + + − 一种反馈回路，其中一个过程的所有输出都可作为该过程的因果输入+ 第20行：
第24行： − 当系统的输出作为输入路由回来，作为形成电路或回路的因果链的一部分时，反馈就发生了。这个系统可以说是自我反馈。因果关系的概念在应用于反馈系统时必须谨慎处理:+ − 第34行：
第37行： − 关于反馈系统的简单因果推理是困难的，因为第一个系统影响第二个系统，第二个系统影响第一个系统，导致循环论证。这使得基于因果的推理变得棘手，因此有必要将系统作为一个整体进行分析。+ 第40行：
第43行： − + 第53行：
第56行： + − 自我调节机制自古以来就存在，到18世纪，反馈的概念开始进入英国的经济理论，但当时它还没有被认为是一个普遍的抽象概念，因此没有名称。+ 第64行：
第68行： − 第一个已知的人工反馈装置是一个浮子阀门，用来维持水的恒定水平，发明于公元前270年在埃及的亚历山大。这个装置说明了反馈原理: 低水位打开阀门，上升的水向系统提供反馈，当达到要求的水位时关闭阀门。随着水位的波动，这种情况会以循环的方式再次发生。这是一个具有里程碑意义的论文控制理论和数学的反馈。+ − 第72行：
第75行： − 19世纪60年代，美国开始使用动词短语反馈，意思是在机械过程中回到原来的位置。1909年，诺贝尔奖获得者卡尔·费迪南德·布劳恩用名词“反馈”来指电子电路元件之间的(不希望的)耦合。+ 第80行：
第83行： − + 第88行：
第91行： − 关注管理理论中的应用，Ramaprasad (1983)将反馈一般定义为“ ... 关于实际水平和系统参数参考水平之间的差距的信息” ，用于“以某种方式改变差距”。他强调，信息本身不是反馈，除非转化为行动。+ − + + 第101行：
第105行： + − 保持一个理想的系统性能，尽管干扰使用负反馈，以减少系统误差+ + 第122行：
第128行： − + 第130行：
第136行： − + + − + + + − “正面”和“负面”这两个词在第二次世界大战之前首次用于反馈。正反馈的想法在20世纪20年代随着再生回路的引入已经很流行了。Friis 和 Jensen (1924)描述了在一套电子放大器的再生情况下，“反馈”行动是积极的，而不是消极反馈行动，他们只是顺便提到。哈罗德·史蒂芬·布莱克1934年的经典论文首次详细阐述了负反馈在电子放大器中的应用。布莱克说:+ + + 第156行：
第167行： − 据 Mindell (2002)说，术语上的混乱是在这之后不久产生的:+ 第162行：
第173行： − + − − + 第175行：
第185行： + + − 一个参数的参考值和实际值之间的差距的改变，根据差距是扩大(正面)还是缩小(负面)。+ + + − 这两个定义可能会引起混淆，例如当一个激励(奖励)被用来提高不良业绩(缩小差距)。参照定义1，一些作者使用替代术语，分别用自我强化/自我纠正、强化/平衡、差异增强/差异减少或再生/退化代替正/负。对于定义2，一些作者主张将行为或效果描述为正/负强化或惩罚，而不是反馈。+ + − 然而，即使在一个单一的学科中，一个反馈的例子也可以被称为正面或负面的，这取决于如何衡量或引用价值观。+ 第202行：
第217行： − 这种混淆可能是因为反馈既可以用于信息目的，也可以用于激励目的，而且通常既有定性的成分，也有定量的成分。正如康奈伦和泽姆克(1993)所说:+ 第217行：
第232行： − + − + 第238行：
第253行： − 反馈在数字系统中被广泛应用。例如，二进制计数器和类似的设备使用反馈，当前状态和输入用于计算一个新的状态，然后反馈回设备并计时以更新它。+ 第247行：
第262行： + − 反馈可以导致难以置信的复杂行为。[[[ Mandelbrot 集(black)在一个连续着色的环境中绘制，方法是通过一个简单的方程反馈值，并记录假想平面上未能发散的点 | alt = ]]+ − + − 通过使用反馈属性，系统的行为可以改变以满足应用程序的需要; 系统可以变得稳定、响应或保持不变。结果表明，具有反馈经验的动力系统具有对混沌边界的适应性。+ 第270行：
第286行： − 在诸如生物体、生态系统或生物圈等生物系统中，在某些环境条件下，大多数参数必须保持在围绕某一最佳水平的狭窄范围内。受控参数最优值的偏差可以由内外环境的变化引起。一些环境条件的改变也可能需要改变这个范围来改变系统的功能。要维持的参数值由接收系统记录并通过信息通道传输到调节模块。胰岛素振荡就是一个例子。+ − 第278行：
第293行： − 生物系统包含许多类型的调节回路，有正回路也有负回路。正如在其他情况下一样，正反馈并不意味着反馈会产生好的或坏的影响。负反馈回路会减慢一个过程，而正反馈回路则会加速这个过程。镜像神经元是社会反馈系统的一部分，当观察到的行为被大脑“镜像” ，就像一个自我执行的行为。+ + − 正常组织的完整性是通过粘附分子介导的不同类型细胞之间的反馈相互作用和作为介质的分泌分子来保持的; 癌症中关键反馈机制的失败扰乱了组织功能。+ 第292行：
第308行： − 在受伤或感染的组织中，炎症介质在细胞中引发反馈反应，改变基因表达，改变表达和分泌的分子群，包括诱导不同细胞合作和恢复组织结构和功能的分子。这种类型的反馈是重要的，因为它能够协调免疫反应和从感染和伤害中恢复。在癌症期间，这种反馈的关键因素失效了。这会破坏组织功能和免疫力。+ − 第300行：
第315行： − 反馈机制首次在细菌中得到阐明，在细菌中营养物质引起了它们某些代谢功能的变化。+ 第306行：
第321行： − + 第314行：
第329行： − 在更大的范围内，即使受到外部变化的深刻影响，反馈也能对动物种群产生稳定作用，尽管反馈反应的时间滞后可能导致捕食者-被捕食者循环。+ − 第322行：
第336行： − 在酶学中，反馈是通过酶在代谢途径中的直接或下游来调节酶的活性的(见别构调节)。+ 第330行：
第344行： − + 第338行：
第352行： − 在心理学中，身体接受来自环境或内部的刺激，从而导致荷尔蒙的释放。然后，荷尔蒙的释放可能会导致更多的荷尔蒙被释放，从而形成一个积极的反馈循环。在某些行为中也发现了这种循环。例如，“羞耻循环”发生在容易脸红的人身上。当他们意识到自己在脸红时，他们会变得更加尴尬，从而导致进一步的脸红，等等。+ 第352行：
第366行： − 气候系统是影响大气、海洋和陆地状态的过程之间强烈的正反馈拥有属性。一个简单的例子是冰反照率正反馈循环，即融化的雪暴露出更多的黑色地面(反照率较低) ，反过来吸收热量，导致更多的雪融化。+ 第364行：
第378行： − 反馈广泛应用于控制理论中，使用了包括状态空间(控件)、全状态反馈等多种方法。请注意，在控制理论的背景下，“反馈”传统上被假定为指定“负反馈”。+ 第372行：
第386行： − 使用控制回路反馈机制的最常见的通用控制器是比例积分微分(PID)控制器。启发式地，PID 控制器的条款可以解释为对应的时间: 比例项取决于当前的错误，积分项积累过去的错误，导数项是一个预测未来的错误，基于当前的变化率。+ 第400行：
第414行： − 荷兰发明家克尼利厄斯·雅布斯纵·戴博尔(1572-1633)建造了恒温器(c1620)来控制鸡的孵化器和化学炉的温度。1745年，铁匠埃德蒙 · 李对风车进行了改进，他在风车的正面加上了扇尾，使风车面朝向风。1787年，汤姆 · 米德通过使用离心摆来调节底石和流水石之间的距离(即调节负荷)来调节风车的转速。+ + 第408行：
第423行： − 1788年 James Watt 使用离心式调速器来调节他的蒸汽机的速度是导致工业革命的一个因素。蒸汽发动机也使用浮子阀和释压阀作为机械调节装置。詹姆斯·克拉克·麦克斯韦在1868年对瓦特的调节器进行了数学分析。+ 第416行：
第431行： − 20世纪后期的内燃机采用了机械反馈机制，如真空定时推进，但机械反馈被电子发动机管理系统所取代，一旦小型、强大和功能强大的单片微控制器变得可以负担得起。+ − + + − − 对 第442行：
第456行： − 如果在控制回路中信号是反向的，系统就称为负反馈; 否则，反馈就称为正反馈。负反馈通常是有意引入的，通过纠正或减少不必要的变化的影响来提高系统的稳定性和准确性。如果输入变化快于系统的响应速度，则此方案可能失败。当这种情况发生时，校正信号到达的滞后可能导致过度校正，导致输出振荡或“捕获”。虽然这种效应通常是系统行为的一个不希望出现的结果，但它却被有意地用于电子振荡器中。+ + + − 贝尔实验室的 Harry Nyquist 推导出了判定反馈系统稳定性的奈奎斯特稳定判据。一个比较简单但不太普遍的方法是使用 hendrikbode 开发的 Bode 图来确定增益裕度和相位裕度。保证稳定性的设计往往涉及频率补偿来控制放大器的极点位置。+ + + − 电子反馈回路用于控制放大器等电子设备的输出。当输出的全部或部分被反馈给输入时，就创建了一个反馈循环。如果没有采用输出反馈，则称装置为操作开环，如果采用反馈，则称装置为闭环。+ − + 第469行：
第487行： + + 第479行：
第499行： + 第484行：
第505行： − 当反馈输出信号相对于输入信号的相位为180 ° (上下颠倒)时，就会产生负反馈。这种情况有时被称为不同相，但这一术语也用来表示其他相分离，如“90 ° 不同相”。负反馈可以用来纠正输出错误，或者使系统对有害的波动不敏感。在反馈放大器中，这种校正通常用于降低波形失真或建立指定的增益电平。获得负反馈放大器的一个通用表达式是渐进增益模型。+ − + + − 当反馈信号与输入信号同相时，就会产生正反馈。在一定的增益条件下，正反馈增强输入信号，使器件的输出在其最大和最小可能状态之间振荡。正反馈也可能在电路中引入滞后现象。这会导致电路忽略小信号，只响应大信号。它有时被用来消除数字信号中的噪声。在某些情况下，正反馈可能导致设备闭锁，即，达到输出锁定到其最大或最小状态的条件。这个事实在数字电子产品中被广泛应用，用来制造信息挥发性记忆体的双稳态电路。+ − 第502行：
第523行： − 有时在音频系统、扩音系统和摇滚乐中发出的响亮的尖叫声被称为音频反馈。如果麦克风位于与之相连的扬声器前面，麦克风拾取的声音就会从扬声器中发出，然后被麦克风拾取并重新放大。如果环路增益是足够的，嚎叫或尖叫在最大功率的放大器是可能的。+ 第518行：
第539行： − 振盪器是一种产生周期性振荡电子信号的电子电路，通常是正弦波或方波。振荡器将直流电从电源转换成交流电信号。它们被广泛应用于许多电子设备中。振荡器产生信号的常见例子包括无线电和电视发射机发出的信号、调节计算机和石英钟的时钟信号，以及电子寻呼机和电子游戏发出的声音。+ − 第536行：
第556行： − 锁存器或触发器是具有两个稳定状态的电路，可用于存储状态信息。它们通常利用电路的两个臂之间交叉的反馈来构造，以便为电路提供一个状态。该电路可以通过施加到一个或多个控制输入的信号来改变状态，并且具有一个或两个输出。它是时序逻辑电路的基本存储元素。锁存器和触发器是用于计算机、通信和许多其他类型系统的数字电子系统的基本构件。+ 第544行：
第564行： − + − 第557行：
第576行： + 第563行：
第583行： − + 第570行：
第590行： − + − + 第595行：
第615行： + 第600行：
第621行： − 视频反馈是视频等效的声学反馈。它涉及一个循环之间的视频摄像机输入和视频输出，例如，一个电视屏幕或显示器。将摄像机对准显示器，根据反馈信息生成复杂的视频图像。+ + 第618行：
第640行： − 股票市场就是这样一个系统的例子，它倾向于振荡性的”捕猎” ，由市场参与者的认知和情感因素所产生的正反馈和负反馈来控制。例如:+ − 第635行：
第656行： + 第640行：
第662行： − 传统的经济均衡/需求模型只支持理想的线性负反馈，Paul Ormerod 在他的《经济学之死》一书中对此进行了严厉的批评，而这本书反过来又遭到了传统经济学家的批评。随着经济学家开始认识到混沌理论适用于包括金融市场在内的非线性反馈系统，这本书是观点转变的一部分。+ 第689行：
第711行： + + 第699行：
第723行： + + 第706行：
第732行： − + + +
无编辑摘要
本词条由11初步翻译
https://wiki.swarma.org/index.php?title=%E5%B9%B3%E8%A1%A1%E7%90%86%E8%AE%BA#:~:text=%E6%9C%AC%E8%AF%8D%E6%9D%A1%E7%94%B1,11%E5%88%9D%E6%AD%A5%E7%BF%BB%E8%AF%91
{{Other uses}}
{{Other uses}}
{{short description|Process where information about current status is used to influence future status}}
{{short description|Process where information about current status is used to influence future status}}
简述|利用当前状态信息影响未来状态的过程
{{Use dmy dates|date=September 2020}}
{{Use dmy dates|date=September 2020}}
{{Complex systems}}[[File:General Feedback Loop.svg|thumb|A feedback loop where all outputs of a process are available as causal inputs to that process]]
{{Complex systems}}[[File:General Feedback Loop.svg|thumb|A feedback loop where all outputs of a process are available as causal inputs to that process]]
使用dmy日期|日期=2020年9月
A feedback loop where all outputs of a process are available as causal inputs to that process
A feedback loop where all outputs of a process are available as causal inputs to that process
一个过程的所有输出都可作为该过程的因果输入的反馈回路。
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:
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:
当一个系统的输出作为输入被送回，作为形成回路或循环的因果链的一部分时，就会产生反馈。这个系统可以说是反馈到了自身。在应用于反馈系统时，必须谨慎处理因果关系的概念。
|text=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.
|text=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.
对一个反馈系统进行简单的因果推理是很困难的，因为第一个系统影响第二个系统，第二个系统影响第一个系统，导致循环论证。这就使得基于因果关系的推理变得很棘手，因此有必要将系统作为一个整体进行分析。
|author=Karl Johan Åström and Richard M.Murray
|author=Karl Johan Åström and Richard M.Murray
|author=Karl Johan Åström and Richard M.Murray
|author=Karl Johan Åström and Richard M.Murray
2012年10月15日 | 作者: 卡尔·约翰·阿斯特洛姆 · 马丁和理查德 · m · 默里
2012年10月15日 | 作者: 卡尔·约翰·阿斯特洛姆 · 马丁Karl Johan Åström和理查德 · M · 默里Richard M.Murray
|title=''Feedback Systems: An Introduction for Scientists and Engineers''<ref>{{cite book |title=Feedback Systems: An Introduction for Scientists and Engineers |author1=Karl Johan Åström |author2=Richard M. Murray |chapter=§1.1: What is feedback? |chapter-url=https://books.google.com/books?id=cdG9fNqTDS8C&q=%22This+makes+reasoning+based+on+cause+and+effect+tricky%22&pg=PA1 |isbn= 9781400828739 |year=2008 |page=1 |publisher=Princeton University Press}} Online version found [http://authors.library.caltech.edu/25062/1/Feedback08.pdf here].
|title=''Feedback Systems: An Introduction for Scientists and Engineers''<ref>{{cite book |title=Feedback Systems: An Introduction for Scientists and Engineers |author1=Karl Johan Åström |author2=Richard M. Murray |chapter=§1.1: What is feedback? |chapter-url=https://books.google.com/books?id=cdG9fNqTDS8C&q=%22This+makes+reasoning+based+on+cause+and+effect+tricky%22&pg=PA1 |isbn= 9781400828739 |year=2008 |page=1 |publisher=Princeton University Press}} Online version found [http://authors.library.caltech.edu/25062/1/Feedback08.pdf here].
==History==
==History==
历史
Self-regulating mechanisms have existed since antiquity, and the idea of feedback had started to enter economic theory in Britain by the 18th century, but it was not at that time recognized as a universal abstraction and so did not have a name.
Self-regulating mechanisms have existed since antiquity, and the idea of feedback had started to enter economic theory in Britain by the 18th century, but it was not at that time recognized as a universal abstraction and so did not have a name.
自我调节机制自古以来就存在，到18世纪，反馈的概念开始进入英国的经济理论，但当时它还不是一个普遍的抽象概念，因此没有名称。
Self-regulating mechanisms have existed since antiquity, and the idea of feedback had started to enter [[Economics|economic theory]] in Britain by the 18th century, but it was not at that time recognized as a universal abstraction and so did not have a name.<ref name=mayr>
Self-regulating mechanisms have existed since antiquity, and the idea of feedback had started to enter [[Economics|economic theory]] in Britain by the 18th century, but it was not at that time recognized as a universal abstraction and so did not have a name.<ref name=mayr>
The first ever known artificial feedback device was a float valve, for maintaining water at a constant level, invented in 270 BC in Alexandria, Egypt. This device illustrated the principle of feedback: a low water level opens the valve, the rising water then provides feedback into the system, closing the valve when the required level is reached. This then reoccurs in a circular fashion as the water level fluctuates. This was a landmark paper on control theory and the mathematics of feedback.
The first ever known artificial feedback device was a float valve, for maintaining water at a constant level, invented in 270 BC in Alexandria, Egypt. This device illustrated the principle of feedback: a low water level opens the valve, the rising water then provides feedback into the system, closing the valve when the required level is reached. This then reoccurs in a circular fashion as the water level fluctuates. This was a landmark paper on control theory and the mathematics of feedback.
第一个已知的人工反馈装置是公元前270年在埃及亚历山大发明的浮阀，用于保持水位恒定。这个装置说明了反馈的原理：低水位打开阀门，上升的水向系统提供反馈，达到所需水位时关闭阀门。然后，随着水位的波动，这种情况会以循环的方式重复发生。这是一篇关于控制理论和反馈数学的里程碑式的论文。
The verb phrase to feed back, in the sense of returning to an earlier position in a mechanical process, was in use in the US by the 1860s, and in 1909, Nobel laureate Karl Ferdinand Braun used the term "feed-back" as a noun to refer to (undesired) coupling between components of an electronic circuit.
The verb phrase to feed back, in the sense of returning to an earlier position in a mechanical process, was in use in the US by the 1860s, and in 1909, Nobel laureate Karl Ferdinand Braun used the term "feed-back" as a noun to refer to (undesired) coupling between components of an electronic circuit.
19世纪60年代，美国开始使用动词短语反馈，意思是在机械过程中回到原来的位置。1909年，诺贝尔奖获得者卡尔·费迪南德·布劳恩Karl Ferdinand Braun用名词“反馈”来指电子电路元件之间的(不希望有的)耦合。
By the end of 1912, researchers using early electronic amplifiers (audions) had discovered that deliberately coupling part of the output signal back to the input circuit would boost the amplification (through regeneration), but would also cause the audion to howl or sing. This action of feeding back of the signal from output to input gave rise to the use of the term "feedback" as a distinct word by 1920.}}
By the end of 1912, researchers using early electronic amplifiers (audions) had discovered that deliberately coupling part of the output signal back to the input circuit would boost the amplification (through regeneration), but would also cause the audion to howl or sing. This action of feeding back of the signal from output to input gave rise to the use of the term "feedback" as a distinct word by 1920.}}
到1912年底，研究人员利用早期电子放大器(音频)发现，故意将输出信号的一部分耦合回输入电路，可以增强放大(通过再生) ，但也会导致音频发出嚎叫或唱歌。这种将信号从输出反馈到输入的行为导致了术语“反馈”在1920年被用作一个不同的词。}
到1912年底，研究人员利用早期电子放大器(三极管)发现，故意将部分输出信号耦合回输入电路，会提高放大率(通过再生)，但也会使试音机发出嚎叫或歌唱声。这种将信号从输出反馈到输入的行为使得 "反馈 "一词在1920年被作为一个独立的词汇使用。}
Focusing on uses in management theory, Ramaprasad (1983) defines feedback generally as "...information about the gap between the actual level and the reference level of a system parameter" that is used to "alter the gap in some way". He emphasizes that the information by itself is not feedback unless translated into action.
Focusing on uses in management theory, Ramaprasad (1983) defines feedback generally as "...information about the gap between the actual level and the reference level of a system parameter" that is used to "alter the gap in some way". He emphasizes that the information by itself is not feedback unless translated into action.
拉马普拉萨德Ramaprasad (1983)侧重于管理理论中的用途，他将反馈一般定义为"……关于系统参数的实际水平与参考水平之间差距的信息"，用于 "以某种方式改变差距"。他强调，信息本身不是反馈，转化为行动才是。”
The verb phrase ''to feed back'', in the sense of returning to an earlier position in a mechanical process, was in use in the US by the 1860s,<ref>
The verb phrase ''to feed back'', in the sense of returning to an earlier position in a mechanical process, was in use in the US by the 1860s,<ref>
动词短语''回馈''，意思是回到机械过程中的早期位置，在美国19世纪60年代就开始使用了，<参考>
''"Heretofore ... it has been necessary to reverse the motion of the rollers, thus causing the material to travel or feed back, ..."''
''"Heretofore ... it has been necessary to reverse the motion of the rollers, thus causing the material to travel or feed back, ..."''
"''以前，要使辊子反向运动，从而使材料移动或回馈……''
HH Cole, "Improvement in Fluting-Machines", [http://www.google.co.nz/patents/US55469 US Patent 55,469 (1866)] accessed 23 March 2012.
HH Cole, "Improvement in Fluting-Machines", [http://www.google.co.nz/patents/US55469 US Patent 55,469 (1866)] accessed 23 March 2012.
''"When the journal or spindle is cut ... and the carriage is about to feed back by a change of the sectional nut or burr upon the screw-shafts, the operator seizes the handle..."'' JM Jay, "Improvement in Machines for Making the Spindles of Wagon-Axles", [http://www.google.co.nz/patents/US47769 US Patent 47,769 (1865)] accessed 23 March 2012.
''"When the journal or spindle is cut ... and the carriage is about to feed back by a change of the sectional nut or burr upon the screw-shafts, the operator seizes the handle..."'' JM Jay, "Improvement in Machines for Making the Spindles of Wagon-Axles", [http://www.google.co.nz/patents/US47769 US Patent 47,769 (1865)] accessed 23 March 2012.
''"当轴颈或主轴被切开......而丝杠轴上的分节螺母或毛刺发生变化，滑块即将回馈时，操作者抓住手柄......"'。JM Jay, "Improve in Machines for Making the Spindles of Wagon-Axles", [http://www.google.co.nz/patents/US47769 US Patent 47,769 (1865)] accessed 23 March 2012.
Maintaining a desired system performance despite disturbance using negative feedback to reduce system error
Maintaining a desired system performance despite disturbance using negative feedback to reduce system error
利用负反馈减少系统误差，在受到干扰的情况下仍能保持理想的系统性能。
</ref> and in 1909, Nobel laureate [[Karl Ferdinand Braun]] used the term "feed-back" as a noun to refer to (undesired) [[Coupling (electronics)|coupling]] between components of an [[electronic circuit]].<ref>''"...as far as possible the circuit has no feed-back into the system being investigated."''
</ref> and in 1909, Nobel laureate [[Karl Ferdinand Braun]] used the term "feed-back" as a noun to refer to (undesired) [[Coupling (electronics)|coupling]] between components of an [[electronic circuit]].<ref>''"...as far as possible the circuit has no feed-back into the system being investigated."''
</参考>而在1909年，诺贝尔奖获得者[[Karl Ferdinand Braun]]使用 "反馈 "一词作为名词，指[[电子电路]]元件之间的（不希望有的）[[耦合（电子学）｜耦合]]。<参考>'''......尽可能使电路没有反馈到正在研究的系统中。
An example of a negative feedback loop with goals
An example of a negative feedback loop with goals
Positive feedback: If the signal fed back from output is in phase with the input signal, the feedback is called positive feedback.
Positive feedback: If the signal fed back from output is in phase with the input signal, the feedback is called positive feedback.
正反馈: 如果输出反馈的信号与输入信号同相，这种反馈称为正反馈。
正反馈: 如果输出反馈的信号与输入信号同相，则称为正反馈。
Negative feedback: If the signal fed back is of opposite polarity or out of phase by 180° with respect to input signal, the feedback is called as negative feedback.
Negative feedback: If the signal fed back is of opposite polarity or out of phase by 180° with respect to input signal, the feedback is called as negative feedback.
负反馈: 如果反馈信号相对于输入信号的极性相反或相位相差180 ° ，这种反馈称为负反馈。
负反馈: 如果反馈信号与输入信号的极性相反或相位相差180 ° ，则称为负反馈。
[https://books.google.com/books?id=1gfKkqB_fTcC]
[https://books.google.com/books?id=1gfKkqB_fTcC]
</ref> This action of feeding back of the signal from output to input gave rise to the use of the term "feedback" as a distinct word by 1920.<ref name=bennett/>
</ref> This action of feeding back of the signal from output to input gave rise to the use of the term "feedback" as a distinct word by 1920.<ref name=bennett/>
</ref>这种将信号从输出反馈到输入的动作，使得 "反馈 "一词在1920年成为一个独立的词汇。<ref name=bennett/>
As an example of negative feedback, the diagram might represent a cruise control system in a car, for example, that matches a target speed such as the speed limit. The controlled system is the car; its input includes the combined torque from the engine and from the changing slope of the road (the disturbance). The car's speed (status) is measured by a speedometer. The error signal is the departure of the speed as measured by the speedometer from the target speed (set point). This measured error is interpreted by the controller to adjust the accelerator, commanding the fuel flow to the engine (the effector). The resulting change in engine torque, the feedback, combines with the torque exerted by the changing road grade to reduce the error in speed, minimizing the road disturbance.
As an example of negative feedback, the diagram might represent a cruise control system in a car, for example, that matches a target speed such as the speed limit. The controlled system is the car; its input includes the combined torque from the engine and from the changing slope of the road (the disturbance). The car's speed (status) is measured by a speedometer. The error signal is the departure of the speed as measured by the speedometer from the target speed (set point). This measured error is interpreted by the controller to adjust the accelerator, commanding the fuel flow to the engine (the effector). The resulting change in engine torque, the feedback, combines with the torque exerted by the changing road grade to reduce the error in speed, minimizing the road disturbance.
作为负反馈的一个例子，该图可以表示汽车中的巡航控制系统，例如，它与目标速度(如车速限制)匹配。受控系统是汽车，其输入包括来自发动机和来自道路坡度变化(扰动)的组合扭矩。汽车的速度(状态)是用速度计测量的。误差信号是速度计测量的速度偏离目标速度(设定点)。这个测量的误差由控制器来解释，以调整加速器，指挥燃料流到发动机(效应器)。由此产生的发动机扭矩的变化，即反馈，与改变路面坡度所施加的扭矩相结合，以减少速度误差，最大限度地减少道路干扰。
作为负反馈的一个例子，该图可以表示汽车中的巡航控制系统，例如，它与目标速度(如车速限制)匹配。受控系统是汽车，其输入包括来自发动机和来自道路坡度变化(干扰)的组合扭矩。汽车的速度(状态)由速度表测量。 误差信号是速度计测量的速度与目标速度（设定点）的偏差。这个测量的误差由控制器来解释，以调整加速器，指挥燃料流到发动机(效应器)。由此产生的发动机扭矩的变化，即反馈，与改变路面坡度所施加的扭矩相结合，以减少速度误差，最大限度地减少道路干扰。
Over the years there has been some dispute as to the best definition of feedback. According to [[William Ross Ashby|Ashby]] (1956), mathematicians and theorists interested in the principles of feedback mechanisms prefer the definition of "circularity of action", which keeps the theory simple and consistent. For those with more practical aims, feedback should be a deliberate effect via some more tangible connection.
Over the years there has been some dispute as to the best definition of feedback. According to [[William Ross Ashby|Ashby]] (1956), mathematicians and theorists interested in the principles of feedback mechanisms prefer the definition of "circularity of action", which keeps the theory simple and consistent. For those with more practical aims, feedback should be a deliberate effect via some more tangible connection.
多年来，对于反馈的最佳定义一直存在一些争议。根据[[威廉·罗斯·阿什比William Ross Ashby|阿什比Ashby]]的说法。(1956)，对反馈机制原理感兴趣的数学家和理论家更喜欢 "作用的循环性 "的定义，这使理论保持简单和一致。对于那些有更多实际目的的人来说，反馈应该是通过一些更有形的联系而产生的一种有意的效果。
The terms "positive" and "negative" were first applied to feedback prior to WWII. The idea of positive feedback was already current in the 1920s with the introduction of the regenerative circuit. Friis and Jensen (1924) described regeneration in a set of electronic amplifiers as a case where the "feed-back" action is positive in contrast to negative feed-back action, which they mention only in passing. Harold Stephen Black's classic 1934 paper first details the use of negative feedback in electronic amplifiers. According to Black:
The terms "positive" and "negative" were first applied to feedback prior to WWII. The idea of positive feedback was already current in the 1920s with the introduction of the regenerative circuit. Friis and Jensen (1924) described regeneration in a set of electronic amplifiers as a case where the "feed-back" action is positive in contrast to negative feed-back action, which they mention only in passing. Harold Stephen Black's classic 1934 paper first details the use of negative feedback in electronic amplifiers. According to Black:
“正面”和“负面”这两个词在第二次世界大战之前首次用于反馈。20世纪20年代，随着再生电路的引入，正反馈的概念已经流行起来。Friis和Jensen(1924)将一套电子放大器中的再生描述为 "反馈"作用是正的，与负的反馈作用相反，他们只是顺便提到了这一点。Harold Stephen Black哈罗德·史蒂芬·布莱克1934年的经典论文首次详细阐述了负反馈在电子放大器中的应用。布莱克说:
{{Quote|[Practical experimenters] object to the mathematician's definition, pointing out that this would force them to say that feedback was present in the ordinary pendulum ... between its position and its momentum—a "feedback" that, from the practical point of view, is somewhat mystical. To this the mathematician retorts that if feedback is to be considered present only when there is an actual wire or nerve to represent it, then the theory becomes chaotic and riddled with irrelevancies.<ref name=Ashby>
{{Quote|[Practical experimenters] object to the mathematician's definition, pointing out that this would force them to say that feedback was present in the ordinary pendulum ... between its position and its momentum—a "feedback" that, from the practical point of view, is somewhat mystical. To this the mathematician retorts that if feedback is to be considered present only when there is an actual wire or nerve to represent it, then the theory becomes chaotic and riddled with irrelevancies.<ref name=Ashby>
{{引言|[实际实验者]反对数学家的定义，指出这将迫使他们说，普通的摆......在其位置和动量之间存在着反馈--这种 "反馈"，从实际的角度看，有些神秘。对此，数学家反驳说，如果只有当有实际的导线或神经来表示反馈时，才认为反馈是存在的，那么这个理论就会变得混乱不堪，充满了无关紧要的东西<ref name=Ashby>。
{{cite book |author=W. Ross Ashby |title=An introduction to cybernetics |publisher=Chapman & Hall |year=1957 |url=http://pcp.vub.ac.be/books/IntroCyb.pdf}}</ref>{{rp|page=54}}}}
{{cite book |author=W. Ross Ashby |title=An introduction to cybernetics |publisher=Chapman & Hall |year=1957 |url=http://pcp.vub.ac.be/books/IntroCyb.pdf}}</ref>{{rp|page=54}}}}
According to Mindell (2002) confusion in the terms arose shortly after this:
According to Mindell (2002) confusion in the terms arose shortly after this:
据明德尔Mindell (2002)说，在这之后不久就出现了术语上的混乱。
Focusing on uses in management theory, Ramaprasad (1983) defines feedback generally as "...information about the gap between the actual level and the reference level of a system parameter" that is used to "alter the gap in some way". He emphasizes that the information by itself is not feedback unless translated into action.<ref name="Ramaprasad">{{Cite journal | doi=10.1002/bs.3830280103|title = On the definition of feedback| journal=Behavioral Science| volume=28| pages=4–13|year = 1983|last1 = Ramaprasad|first1 = Arkalgud}}</ref>
Focusing on uses in management theory, Ramaprasad (1983) defines feedback generally as "...information about the gap between the actual level and the reference level of a system parameter" that is used to "alter the gap in some way". He emphasizes that the information by itself is not feedback unless translated into action.<ref name="Ramaprasad">{{Cite journal | doi=10.1002/bs.3830280103|title = On the definition of feedback| journal=Behavioral Science| volume=28| pages=4–13|year = 1983|last1 = Ramaprasad|first1 = Arkalgud}}</ref>
{{Quote|...Friis and Jensen had made the same distinction Black used between "positive feed-back" and "negative feed-back", based not on the sign of the feedback itself but rather on its effect on the amplifier's gain. In contrast, Nyquist and Bode, when they built on Black's work, referred to negative feedback as that with the sign reversed. Black had trouble convincing others of the utility of his invention in part because confusion existed over basic matters of definition.
{{Quote|...Friis and Jensen had made the same distinction Black used between "positive feed-back" and "negative feed-back", based not on the sign of the feedback itself but rather on its effect on the amplifier's gain. In contrast, Nyquist and Bode, when they built on Black's work, referred to negative feedback as that with the sign reversed. Black had trouble convincing others of the utility of his invention in part because confusion existed over basic matters of definition.
{{ Quote | ... Friis 和 Jensen 对 Black 所用的“正反馈”和“负反馈”作了同样的区分，不是基于反馈本身的符号，而是基于它对放大器增益的影响。相比之下，当 Nyquist 和 Bode 基于 Black 的研究成果时，他们将负面反馈称为符号相反的负面反馈。布莱克很难说服其他人相信他的发明是有用的，部分原因是在基本的定义问题上存在混淆。
{{Quote|...Friis和Jensen对Black在 "正反馈 "和 "负反馈 "之间的区分是一样的，不是基于反馈本身的符号，而是基于它对放大器增益的影响。相反，Nyquist和Bode在Black的工作基础上，将负反馈称为符号相反的反馈。Black难以说服其他人相信他的发明的效用，部分原因是在基本的定义问题上存在混乱。
==Types==
==Types==
类型
===Positive and negative feedback===
===Positive and negative feedback===
正反馈和负反馈
{{Main|Negative feedback|Positive feedback}}
{{Main|Negative feedback|Positive feedback}}
主要|消极反馈|积极反馈
the altering of the gap between reference and actual values of a parameter, based on whether the gap is widening (positive) or narrowing (negative).
the altering of the gap between reference and actual values of a parameter, based on whether the gap is widening (positive) or narrowing (negative).
根据差距是扩大（正）还是缩小（负）改变一个参数的参考值和实际值之间的差距；、
[[File:Set-point control.png|thumb|350px|Maintaining a desired system performance despite disturbance using negative feedback to reduce system error]]
[[File:Set-point control.png|thumb|350px|Maintaining a desired system performance despite disturbance using negative feedback to reduce system error]]
[[File:Set-point control.png|thumb|350px|利用负反馈减少系统误差，在受到干扰的情况下仍能保持理想的系统性能]]
[[File:Outcome Feedback Negative Feedback Loop.png|thumb|An example of a negative feedback loop with goals]]
[[File:Outcome Feedback Negative Feedback Loop.png|thumb|An example of a negative feedback loop with goals]]
[[文件：结果反馈负反馈Loop.png |拇指|目标负反馈循环的示例]]
The two definitions may cause confusion, such as when an incentive (reward) is used to boost poor performance (narrow a gap). Referring to definition 1, some authors use alternative terms, replacing positive/negative with self-reinforcing/self-correcting, reinforcing/balancing, discrepancy-enhancing/discrepancy-reducing or regenerative/degenerative respectively. And for definition 2, some authors advocate describing the action or effect as positive/negative reinforcement or punishment rather than feedback.
The two definitions may cause confusion, such as when an incentive (reward) is used to boost poor performance (narrow a gap). Referring to definition 1, some authors use alternative terms, replacing positive/negative with self-reinforcing/self-correcting, reinforcing/balancing, discrepancy-enhancing/discrepancy-reducing or regenerative/degenerative respectively. And for definition 2, some authors advocate describing the action or effect as positive/negative reinforcement or punishment rather than feedback.
这两个定义可能会引起混淆，例如，当激励(奖励)被用来提高不良绩效(缩小差距)时。关于定义1，一些作者使用了其他术语，分别用自我强化/自我纠正、强化/平衡、增强差异/减少差异或再生/退化来代替积极/消极。对于定义2，一些作者主张将行为或效果描述为正/负强化或惩罚，而不是反馈。
[[File:Process Feedback Loop.png|thumb|A positive feedback loop example]]
[[File:Process Feedback Loop.png|thumb|A positive feedback loop example]]
[[File：Process Feedback Loop.png | thumb |正反馈循环示例]]
Yet even within a single discipline an example of feedback can be called either positive or negative, depending on how values are measured or referenced.
Yet even within a single discipline an example of feedback can be called either positive or negative, depending on how values are measured or referenced.
然而，即使在单一学科内，也可以根据值的测量或引用方式将反馈示例称为正反馈或负反馈。
Positive feedback: If the signal fed back from output is in phase with the input signal, the feedback is called positive feedback.
Positive feedback: If the signal fed back from output is in phase with the input signal, the feedback is called positive feedback.
This confusion may arise because feedback can be used for either informational or motivational purposes, and often has both a qualitative and a quantitative component. As Connellan and Zemke (1993) put it:
This confusion may arise because feedback can be used for either informational or motivational purposes, and often has both a qualitative and a quantitative component. As Connellan and Zemke (1993) put it:
这种混淆可能出现是因为反馈既可以用于信息目的，也可以用于激励目的，而且往往既有定性的内容，也有定量的内容。正如康奈伦Connellan和泽姆克Zemke (1993)所说:
Negative feedback: If the signal fed back is of opposite polarity or out of phase by 180° with respect to input signal, the feedback is called as negative feedback.
Negative feedback: If the signal fed back is of opposite polarity or out of phase by 180° with respect to input signal, the feedback is called as negative feedback.
The terms "positive" and "negative" were first applied to feedback prior to WWII. The idea of positive feedback was already current in the 1920s with the introduction of the [[regenerative circuit]].<ref name=mindell>
The terms "positive" and "negative" were first applied to feedback prior to WWII. The idea of positive feedback was already current in the 1920s with the introduction of the [[regenerative circuit]].<ref name=mindell>
"正反馈 "和 "负反馈 "这两个术语在二战前首次应用于反馈。20世纪20年代，随着[[再生电路]]的问世，正反馈的概念已经开始流行。
{{Cite book
{{Cite book
{{Quote|When there are only two parts joined so that each affects the other, the properties of the feedback give important and useful information about the properties of the whole. But when the parts rise to even as few as four, if every one affects the other three, then twenty circuits can be traced through them; and knowing the properties of all the twenty circuits does not give complete information about the system.
{{Quote|When there are only two parts joined so that each affects the other, the properties of the feedback give important and useful information about the properties of the whole. But when the parts rise to even as few as four, if every one affects the other three, then twenty circuits can be traced through them; and knowing the properties of all the twenty circuits does not give complete information about the system.
{{ Quote | 当只有两个部分相互连接时，反馈的属性提供了关于整体属性的重要而有用的信息。但是，当这些部件甚至上升到4个，如果每一个都影响其他3个，那么二十个电路可以通过他们追踪; 并且知道所有二十个电路的特性并不能给出关于这个系统的完整信息。
{{引言|当只有两个部分连接在一起，以至于每个部分都会影响到另一个部分时，反馈的特性就能提供关于整体特性的重要而有用的信息。但是，当部分增加到甚至只有四个时，如果每一个部分都影响其他三个部分，那么就可以通过它们追踪到二十个回路；而知道所有二十个回路的特性并不能提供系统的完整信息。
|author=David A. Mindell
|author=David A. Mindell
Feedback is used extensively in digital systems. For example, binary counters and similar devices employ feedback where the current state and inputs are used to calculate a new state which is then fed back and clocked back into the device to update it.
Feedback is used extensively in digital systems. For example, binary counters and similar devices employ feedback where the current state and inputs are used to calculate a new state which is then fed back and clocked back into the device to update it.
反馈在数字系统中被广泛应用。例如，二进制计数器和类似的设备使用反馈，当前状态和输入用于计算一个新的状态，然后反馈回设备并计时更新。
|location=Baltimore, MD, US
|location=Baltimore, MD, US
</ref> Friis and Jensen (1924) described regeneration in a set of electronic amplifiers as a case where ''the "feed-back" action is positive'' in contrast to negative feed-back action, which they mention only in passing.<ref name=friis>
</ref> Friis and Jensen (1924) described regeneration in a set of electronic amplifiers as a case where ''the "feed-back" action is positive'' in contrast to negative feed-back action, which they mention only in passing.<ref name=friis>
</ref> Friis和Jensen (1924)将一套电子放大器中的再生描述为"'反馈'作用是积极的"，而不是消极的反馈作用，他们只是顺便提到了这一点。
Feedback can give rise to incredibly complex behaviors. The [[Mandelbrot set (black) within a continuously colored environment is plotted by repeatedly feeding back values through a simple equation and recording the points on the imaginary plane that fail to diverge|alt=]]
Feedback can give rise to incredibly complex behaviors. The [[Mandelbrot set (black) within a continuously colored environment is plotted by repeatedly feeding back values through a simple equation and recording the points on the imaginary plane that fail to diverge|alt=]]
反馈可以产生令人难以置信的复杂行为。通过一个简单的方程反复反馈数值，并记录虚平面上未能偏离的点，绘制出连续着色环境中的[[曼德尔布罗特集（布莱克）]]。
Friis, H.T., and A.G.Jensen. "High Frequency Amplifiers" Bell System Technical Journal 3 (April 1924):181–205.</ref> [[Harold Stephen Black]]'s classic 1934 paper first details the use of negative feedback in electronic amplifiers. According to Black:
Friis, H.T., and A.G.Jensen. "High Frequency Amplifiers" Bell System Technical Journal 3 (April 1924):181–205.</ref> [[Harold Stephen Black]]'s classic 1934 paper first details the use of negative feedback in electronic amplifiers. According to Black:
Friis，H.T.和A.G.Jensen。"高频放大器 "贝尔系统技术杂志 3（1924 年 4 月）：181-205.</参考> 根据Black的说法，[[哈罗德-斯蒂芬-布莱克]]1934 年的经典论文首次详细介绍了电子放大器中负反馈的使用。
By using feedback properties, the behavior of a system can be altered to meet the needs of an application; systems can be made stable, responsive or held constant. It is shown that dynamical systems with a feedback experience an adaptation to the edge of chaos.
By using feedback properties, the behavior of a system can be altered to meet the needs of an application; systems can be made stable, responsive or held constant. It is shown that dynamical systems with a feedback experience an adaptation to the edge of chaos.
通过利用反馈特性，可以改变系统的行为，以满足应用的需要；可以使系统变得稳定、灵敏或保持不变。研究表明，具有反馈经验的动力系统具有对混沌边界的适应性。
{{Quote|Positive feed-back increases the gain of the amplifier, negative feed-back reduces it.<ref name=black>
{{Quote|Positive feed-back increases the gain of the amplifier, negative feed-back reduces it.<ref name=black>
In biological systems such as organisms, ecosystems, or the biosphere, most parameters must stay under control within a narrow range around a certain optimal level under certain environmental conditions. The deviation of the optimal value of the controlled parameter can result from the changes in internal and external environments. A change of some of the environmental conditions may also require change of that range to change for the system to function. The value of the parameter to maintain is recorded by a reception system and conveyed to a regulation module via an information channel. An example of this is insulin oscillations.
In biological systems such as organisms, ecosystems, or the biosphere, most parameters must stay under control within a narrow range around a certain optimal level under certain environmental conditions. The deviation of the optimal value of the controlled parameter can result from the changes in internal and external environments. A change of some of the environmental conditions may also require change of that range to change for the system to function. The value of the parameter to maintain is recorded by a reception system and conveyed to a regulation module via an information channel. An example of this is insulin oscillations.
在生物体、生态系统或生物圈等生物系统中，在一定的环境条件下，大多数参数必须保持在围绕一定的最佳水平的狭窄范围内受控。受控参数最佳值的偏离可能是由于内外部环境的变化造成的。一些环境条件的变化也可能要求改变该范围，系统才能发挥作用。要保持的参数值由接收系统记录下来，并通过信息通道传达给调节模块。胰岛素振荡就是一个例子。
Biological systems contain many types of regulatory circuits, both positive and negative. As in other contexts, positive and negative do not imply that the feedback causes good or bad effects. A negative feedback loop is one that tends to slow down a process, whereas the positive feedback loop tends to accelerate it. The mirror neurons are part of a social feedback system, when an observed action is "mirrored" by the brain—like a self-performed action.
Biological systems contain many types of regulatory circuits, both positive and negative. As in other contexts, positive and negative do not imply that the feedback causes good or bad effects. A negative feedback loop is one that tends to slow down a process, whereas the positive feedback loop tends to accelerate it. The mirror neurons are part of a social feedback system, when an observed action is "mirrored" by the brain—like a self-performed action.
生物系统包含许多类型的调节回路，包括正向和负向。与其他情况一样，正负并不意味着反馈会造成好的或坏的影响。负反馈回路是一种倾向于减缓过程的回路，而正反馈回路则倾向于加速过程。镜像神经元是社会反馈系统的一部分，当观察到的行为被大脑“镜像” ，就像一个自我执行的行为。
====Terminology====
====Terminology====
术语
Normal tissue integrity is preserved by feedback interactions between diverse cell types mediated by adhesion molecules and secreted molecules that act as mediators; failure of key feedback mechanisms in cancer disrupts tissue function.
Normal tissue integrity is preserved by feedback interactions between diverse cell types mediated by adhesion molecules and secreted molecules that act as mediators; failure of key feedback mechanisms in cancer disrupts tissue function.
正常组织的完整性是通过粘附分子和作为介质的分泌分子介导的不同细胞类型之间的反馈相互作用来保持的；癌症中关键反馈机制的失效会破坏组织功能。
The terms positive and negative feedback are defined in different ways within different disciplines.
The terms positive and negative feedback are defined in different ways within different disciplines.
In an injured or infected tissue, inflammatory mediators elicit feedback responses in cells, which alter gene expression, and change the groups of molecules expressed and secreted, including molecules that induce diverse cells to cooperate and restore tissue structure and function. This type of feedback is important because it enables coordination of immune responses and recovery from infections and injuries. During cancer, key elements of this feedback fail. This disrupts tissue function and immunity.
In an injured or infected tissue, inflammatory mediators elicit feedback responses in cells, which alter gene expression, and change the groups of molecules expressed and secreted, including molecules that induce diverse cells to cooperate and restore tissue structure and function. This type of feedback is important because it enables coordination of immune responses and recovery from infections and injuries. During cancer, key elements of this feedback fail. This disrupts tissue function and immunity.
在受伤或感染的组织中，炎症介质会引起细胞的反馈反应，改变基因表达，改变表达和分泌的分子群，包括诱导不同细胞合作和恢复组织结构和功能的分子。这种类型的反馈很重要，因为它能够协调免疫反应、使其从感染和损伤中恢复。在癌症过程中，这种反馈的关键要素会失效，进而破坏组织功能和免疫力。
Mechanisms of feedback were first elucidated in bacteria, where a nutrient elicits changes in some of their metabolic functions.
Mechanisms of feedback were first elucidated in bacteria, where a nutrient elicits changes in some of their metabolic functions.
反馈机制首次在细菌中得到阐明，一种营养物质会引起其部分代谢功能的变化。。
# the [[Valence (psychology)|valence]] of the ''action'' or ''effect'' that alters the gap, based on whether it has a ''happy'' (positive) or ''unhappy'' (negative) emotional connotation to the recipient or observer.<ref name=herold1977>Herold, David M., and Martin M. Greller. "Research Notes. FEEDBACK THE DEFINITION OF A CONSTRUCT." Academy of management Journal 20.1 (1977): 142-147.</ref>
# the [[Valence (psychology)|valence]] of the ''action'' or ''effect'' that alters the gap, based on whether it has a ''happy'' (positive) or ''unhappy'' (negative) emotional connotation to the recipient or observer.<ref name=herold1977>Herold, David M., and Martin M. Greller. "Research Notes. FEEDBACK THE DEFINITION OF A CONSTRUCT." Academy of management Journal 20.1 (1977): 142-147.</ref>
Feedback is also central to the operations of genes and gene regulatory networks. Repressor (see Lac repressor) and activator proteins are used to create genetic operons, which were identified by Francois Jacob and Jacques Monod in 1961 as feedback loops. These feedback loops may be positive (as in the case of the coupling between a sugar molecule and the proteins that import sugar into a bacterial cell), or negative (as is often the case in metabolic consumption).
Feedback is also central to the operations of genes and gene regulatory networks. Repressor (see Lac repressor) and activator proteins are used to create genetic operons, which were identified by Francois Jacob and Jacques Monod in 1961 as feedback loops. These feedback loops may be positive (as in the case of the coupling between a sugar molecule and the proteins that import sugar into a bacterial cell), or negative (as is often the case in metabolic consumption).
反馈也是基因和基因调控网络运作的中心。阻遏蛋白(参见 Lac 阻遏蛋白)和激活蛋白被用来创造基因操纵子，这被 Francois Jacob 和 Jacques Monod 在1961年确定为反馈回路。这些反馈回路可能是正的(例如糖分子和将糖输入细菌细胞的蛋白质之间的耦合) ，也可能是负的(例如代谢消耗中经常出现的情况)。
反馈也是基因和基因调控网络运作的中心。阻遏蛋白(参见 Lac 阻遏蛋白)和激活蛋白被用来创造基因操纵子，这被 弗朗索瓦·雅各布Francois Jacob 和雅克·莫诺德 Jacques Monod 在1961年确定为反馈回路。这些反馈回路可能是正的(例如糖分子和将糖输入细菌细胞的蛋白质之间的耦合) ，也可能是负的(例如代谢消耗中经常出现的情况)。
On a larger scale, feedback can have a stabilizing effect on animal populations even when profoundly affected by external changes, although time lags in feedback response can give rise to predator-prey cycles.
On a larger scale, feedback can have a stabilizing effect on animal populations even when profoundly affected by external changes, although time lags in feedback response can give rise to predator-prey cycles.
在更大的范围内，即使受到外部变化的深刻影响，反馈也能对动物种群产生稳定作用，尽管反馈反应的时间滞后可能导致引起捕食者与猎物的循环。
{{Cite book
{{Cite book
In zymology, feedback serves as regulation of activity of an enzyme by its direct or downstream in the metabolic pathway (see Allosteric regulation).
In zymology, feedback serves as regulation of activity of an enzyme by its direct or downstream in the metabolic pathway (see Allosteric regulation).
在酶学中，反馈通过酶在代谢途径中的直接或下游调节酶的活性(见'''<font color="#ff8000"> 别构调节allosteric regulation </font>''')。
|title=The Fifth Discipline: The Art and Practice of the Learning Organization
|title=The Fifth Discipline: The Art and Practice of the Learning Organization
The hypothalamic–pituitary–adrenal axis is largely controlled by positive and negative feedback, much of which is still unknown.
The hypothalamic–pituitary–adrenal axis is largely controlled by positive and negative feedback, much of which is still unknown.
下丘脑-垂体-肾上腺轴在很大程度上受正反馈和负反馈控制，其中大部分仍然是未知的。
下丘脑-垂体-肾上腺轴在很大程度上受正反馈和负反馈控制，其中大部分内容仍然是未知的。
|publisher=Doubleday
|publisher=Doubleday
In psychology, the body receives a stimulus from the environment or internally that causes the release of hormones. Release of hormones then may cause more of those hormones to be released, causing a positive feedback loop. This cycle is also found in certain behaviour. For example, "shame loops" occur in people who blush easily. When they realize that they are blushing, they become even more embarrassed, which leads to further blushing, and so on.
In psychology, the body receives a stimulus from the environment or internally that causes the release of hormones. Release of hormones then may cause more of those hormones to be released, causing a positive feedback loop. This cycle is also found in certain behaviour. For example, "shame loops" occur in people who blush easily. When they realize that they are blushing, they become even more embarrassed, which leads to further blushing, and so on.
在心理学中，身体接受来自环境或内部的刺激，从而导致荷尔蒙的释放。然后，荷尔蒙的释放可能会导致更多的荷尔蒙被释放，从而形成正反馈循环。这种循环也存在于某些行为中。例如，容易脸红的人就会出现 "羞耻循环"。当他们意识到自己脸红的时候，他们会变得更加尴尬，从而导致进一步的脸红，等等。
|isbn=978-0-385-26094-7
|isbn=978-0-385-26094-7
The climate system is characterized by strong positive and negative feedback loops between processes that affect the state of the atmosphere, ocean, and land. A simple example is the ice-albedo positive feedback loop whereby melting snow exposes more dark ground (of lower albedo), which in turn absorbs heat and causes more snow to melt.
The climate system is characterized by strong positive and negative feedback loops between processes that affect the state of the atmosphere, ocean, and land. A simple example is the ice-albedo positive feedback loop whereby melting snow exposes more dark ground (of lower albedo), which in turn absorbs heat and causes more snow to melt.
气候系统的特点是，影响大气、海洋和陆地状态的过程之间存在着强烈的正负反馈回路。一个简单的例子是冰-反照率正反馈环路，即雪的融化使更多的黑暗地面(反照率较低)暴露出来，反过来吸收热量，使更多的雪融化。
John D. Sterman, ''Business Dynamics: Systems Thinking and Modeling for a Complex World'', McGraw Hill/Irwin, 2000. {{ISBN|978-0-07-238915-9}}
John D. Sterman, ''Business Dynamics: Systems Thinking and Modeling for a Complex World'', McGraw Hill/Irwin, 2000. {{ISBN|978-0-07-238915-9}}
Feedback is extensively used in control theory, using a variety of methods including state space (controls), full state feedback, and so forth. Note that in the context of control theory, "feedback" is traditionally assumed to specify "negative feedback".
Feedback is extensively used in control theory, using a variety of methods including state space (controls), full state feedback, and so forth. Note that in the context of control theory, "feedback" is traditionally assumed to specify "negative feedback".
反馈广泛应用于控制理论中，使用的方法很多，包括状态空间（控制）、全状态反馈等。需要注意的是，在控制理论的背景下，“反馈”传统上被假定为指定“负反馈”。
Hermann A Haus and Richard B. Adler, ''Circuit Theory of Linear Noisy Networks'', MIT Press, 1959
Hermann A Haus and Richard B. Adler, ''Circuit Theory of Linear Noisy Networks'', MIT Press, 1959
The most common general-purpose controller using a control-loop feedback mechanism is a proportional-integral-derivative (PID) controller. Heuristically, the terms of a PID controller can be interpreted as corresponding to time: the proportional term depends on the present error, the integral term on the accumulation of past errors, and the derivative term is a prediction of future error, based on current rate of change.
The most common general-purpose controller using a control-loop feedback mechanism is a proportional-integral-derivative (PID) controller. Heuristically, the terms of a PID controller can be interpreted as corresponding to time: the proportional term depends on the present error, the integral term on the accumulation of past errors, and the derivative term is a prediction of future error, based on current rate of change.
最常见的采用控制回路反馈机制的通用控制器是比例-积分-导数（PID）控制器。从启发式的角度看，PID控制器的项可以解释为与时间相对应：比例项取决于现在的误差，积分项取决于过去误差的积累，而导数项则是根据当前的变化率，对未来误差进行预测。
BF Skinner, ''The Experimental Analysis of Behavior'', American Scientist, Vol. 45, No. 4 (SEPTEMBER 1957), pp. 343-371</ref>
BF Skinner, ''The Experimental Analysis of Behavior'', American Scientist, Vol. 45, No. 4 (SEPTEMBER 1957), pp. 343-371</ref>
The Dutch inventor Cornelius Drebbel (1572-1633) built thermostats (c1620) to control the temperature of chicken incubators and chemical furnaces. In 1745, the windmill was improved by blacksmith Edmund Lee, who added a fantail to keep the face of the windmill pointing into the wind. In 1787, Tom Mead regulated the rotation speed of a windmill by using a centrifugal pendulum to adjust the distance between the bedstone and the runner stone (i.e., to adjust the load).
The Dutch inventor Cornelius Drebbel (1572-1633) built thermostats (c1620) to control the temperature of chicken incubators and chemical furnaces. In 1745, the windmill was improved by blacksmith Edmund Lee, who added a fantail to keep the face of the windmill pointing into the wind. In 1787, Tom Mead regulated the rotation speed of a windmill by using a centrifugal pendulum to adjust the distance between the bedstone and the runner stone (i.e., to adjust the load).
荷兰发明家克尼利厄斯·雅布斯纵·戴博尔Cornelius Drebbel (1572-1633)制造了恒温器(c1620)用于控制鸡的孵化器和化学炉的温度。1745年，铁匠埃德蒙 · 李Edmund Lee对风车进行了改进，他增加了一个扇形尾翼，使风车的表面一直指向风中。1787年，汤姆 · 米德Tom Mead通过使用离心摆调节底石和流水石之间的距离(即调节负荷)来调节风车的转速。
====Limitations of negative and positive feedback====
====Limitations of negative and positive feedback====
正反馈和负反馈的限制
While simple systems can sometimes be described as one or the other type, many systems with feedback loops cannot be so easily designated as simply positive or negative, and this is especially true when multiple loops are present.
While simple systems can sometimes be described as one or the other type, many systems with feedback loops cannot be so easily designated as simply positive or negative, and this is especially true when multiple loops are present.
The use of the centrifugal governor by James Watt in 1788 to regulate the speed of his steam engine was one factor leading to the Industrial Revolution. Steam engines also use float valves and pressure release valves as mechanical regulation devices. A mathematical analysis of Watt's governor was done by James Clerk Maxwell in 1868.
The use of the centrifugal governor by James Watt in 1788 to regulate the speed of his steam engine was one factor leading to the Industrial Revolution. Steam engines also use float valves and pressure release valves as mechanical regulation devices. A mathematical analysis of Watt's governor was done by James Clerk Maxwell in 1868.
1788年，詹姆斯·瓦特James Watt 使用离心式调速器来调节他的蒸汽机的速度是导致工业革命的一个因素。蒸汽发动机也使用浮子阀和释压阀作为机械调节装置。詹姆斯·克拉克·麦克斯韦James Clerk Maxwell在1868年对瓦特的调节器进行了数学分析。
Internal combustion engines of the late 20th century employed mechanical feedback mechanisms such as the vacuum timing advance but mechanical feedback was replaced by electronic engine management systems once small, robust and powerful single-chip microcontrollers became affordable.
Internal combustion engines of the late 20th century employed mechanical feedback mechanisms such as the vacuum timing advance but mechanical feedback was replaced by electronic engine management systems once small, robust and powerful single-chip microcontrollers became affordable.
20世纪后期的内燃机采用了机械反馈机制，如真空定时推进，但一旦小型、坚固和功能强大的单片机变得经济实惠，机械反馈就被电子发动机管理系统所取代。
===Other types of feedback===
===Other types of feedback===
其他反馈类型
In general, feedback systems can have many signals fed back and the feedback loop frequently contain mixtures of positive and negative feedback where positive and negative feedback can dominate at different frequencies or different points in the state space of a system.
In general, feedback systems can have many signals fed back and the feedback loop frequently contain mixtures of positive and negative feedback where positive and negative feedback can dominate at different frequencies or different points in the state space of a system.
一般来说，反馈系统可以有许多信号反馈，反馈回路中经常包含正反馈和负反馈的混合物，其中正反馈和负反馈可以在系统状态空间的不同频率或不同点占主导地位。
right
right
If the signal is inverted on its way round the control loop, the system is said to have negative feedback; otherwise, the feedback is said to be positive. Negative feedback is often deliberately introduced to increase the stability and accuracy of a system by correcting or reducing the influence of unwanted changes. This scheme can fail if the input changes faster than the system can respond to it. When this happens, the lag in arrival of the correcting signal can result in over-correction, causing the output to oscillate or "hunt". While often an unwanted consequence of system behaviour, this effect is used deliberately in electronic oscillators.
If the signal is inverted on its way round the control loop, the system is said to have negative feedback; otherwise, the feedback is said to be positive. Negative feedback is often deliberately introduced to increase the stability and accuracy of a system by correcting or reducing the influence of unwanted changes. This scheme can fail if the input changes faster than the system can respond to it. When this happens, the lag in arrival of the correcting signal can result in over-correction, causing the output to oscillate or "hunt". While often an unwanted consequence of system behaviour, this effect is used deliberately in electronic oscillators.
如果信号在绕过控制环路的过程中发生了反转，则称系统为负反馈；否则，称反馈为正反馈。负反馈常常被刻意引入，通过纠正或减少不需要的变化的影响来提高系统的稳定性和准确性。 如果输入的变化速度快于系统对它的响应速度，这种方案就会失效。当这种情况发生时，校正信号到达的滞后可能导致过度校正，导致输出振荡或“捕获”。虽然这种效应通常是系统行为的一个不希望出现的结果，但它却被有意地用于电子振荡器中。
Some systems with feedback can have very complex behaviors such as [[Chaos theory|chaotic behaviors]] in non-linear systems, while others have much more predictable behaviors, such as those that are used to make and design digital systems.
Some systems with feedback can have very complex behaviors such as [[Chaos theory|chaotic behaviors]] in non-linear systems, while others have much more predictable behaviors, such as those that are used to make and design digital systems.
一些带有反馈的系统可以有非常复杂的行为，比如非线性系统中的[[混沌理论|混沌行为]]，而另一些系统则有更多可预测的行为，比如那些用于制造和设计数字系统的系统。
Harry Nyquist at Bell Labs derived the Nyquist stability criterion for determining the stability of feedback systems. An easier method, but less general, is to use Bode plots developed by Hendrik Bode to determine the gain margin and phase margin. Design to ensure stability often involves frequency compensation to control the location of the poles of the amplifier.
Harry Nyquist at Bell Labs derived the Nyquist stability criterion for determining the stability of feedback systems. An easier method, but less general, is to use Bode plots developed by Hendrik Bode to determine the gain margin and phase margin. Design to ensure stability often involves frequency compensation to control the location of the poles of the amplifier.
贝尔实验室的哈里·奈奎斯特 Harry Nyquist 推导出了判定反馈系统稳定性的奈奎斯特稳定判据。一个比较简单但不太普遍的方法是使用 hendrikbode 开发的 Bode 图来确定增益裕度和相位裕度。保证稳定性的设计往往涉及频率补偿来控制放大器的极点位置。
Feedback is used extensively in digital systems. For example, binary counters and similar devices employ feedback where the current state and inputs are used to calculate a new state which is then fed back and clocked back into the device to update it.
Feedback is used extensively in digital systems. For example, binary counters and similar devices employ feedback where the current state and inputs are used to calculate a new state which is then fed back and clocked back into the device to update it.
反馈在数字系统中得到了广泛的应用。例如，二进制计数器和类似的设备采用了反馈，即利用当前的状态和输入来计算一个新的状态，然后反馈到设备并将其时钟化以更新它。
Electronic feedback loops are used to control the output of electronic devices, such as amplifiers. A feedback loop is created when all or some portion of the output is fed back to the input. A device is said to be operating open loop if no output feedback is being employed and closed loop if feedback is being used.
Electronic feedback loops are used to control the output of electronic devices, such as amplifiers. A feedback loop is created when all or some portion of the output is fed back to the input. A device is said to be operating open loop if no output feedback is being employed and closed loop if feedback is being used.
电子反馈环路用于控制电子设备的输出，如放大器。当所有或部分输出反馈到输入时，就形成了一个反馈回路。如果没有采用输出反馈，则称为开环运行，如果采用反馈，则称为闭环运行。
==Applications==
==Applications==
应用
When two or more amplifiers are cross-coupled using positive feedback, complex behaviors can be created. These multivibrators are widely used and include:
When two or more amplifiers are cross-coupled using positive feedback, complex behaviors can be created. These multivibrators are widely used and include:
===Mathematics and dynamical systems===
===Mathematics and dynamical systems===
数学和动力系统
[[File:Mandel zoom 00 mandelbrot set.jpg|322px|thumb|Feedback can give rise to incredibly complex behaviors. The [[Mandelbrot set]] (black) within a continuously colored environment is plotted by repeatedly feeding back values through a simple equation and recording the points on the imaginary plane that fail to diverge|alt=]]
[[File:Mandel zoom 00 mandelbrot set.jpg|322px|thumb|Feedback can give rise to incredibly complex behaviors. The [[Mandelbrot set]] (black) within a continuously colored environment is plotted by repeatedly feeding back values through a simple equation and recording the points on the imaginary plane that fail to diverge|alt=]]
[[File:Mandel zoom 00 mandelbrot set.jpg|322px|thumb|反馈可以产生令人难以置信的复杂行为。[[曼德尔布罗特集]]。(black)在一个连续着色的环境中，通过一个简单的方程反复反馈数值，并记录在虚平面上未能偏离的点|alt=]]来绘制。
{{Main|Dynamical system|Chaos theory|Edge of chaos|Control theory}}
{{Main|Dynamical system|Chaos theory|Edge of chaos|Control theory}}
===Biology===
===Biology===
生物
{{See also|Homeostasis|Allostasis}}
{{See also|Homeostasis|Allostasis}}
A Negative feedback occurs when the fed-back output signal has a relative phase of 180° with respect to the input signal (upside down). This situation is sometimes referred to as being out of phase, but that term also is used to indicate other phase separations, as in "90° out of phase". Negative feedback can be used to correct output errors or to desensitize a system to unwanted fluctuations. In feedback amplifiers, this correction is generally for waveform distortion reduction or to establish a specified gain level. A general expression for the gain of a negative feedback amplifier is the asymptotic gain model.
A Negative feedback occurs when the fed-back output signal has a relative phase of 180° with respect to the input signal (upside down). This situation is sometimes referred to as being out of phase, but that term also is used to indicate other phase separations, as in "90° out of phase". Negative feedback can be used to correct output errors or to desensitize a system to unwanted fluctuations. In feedback amplifiers, this correction is generally for waveform distortion reduction or to establish a specified gain level. A general expression for the gain of a negative feedback amplifier is the asymptotic gain model.
当反馈的输出信号相对于输入信号有180°的相对相位（上下颠倒）时，就会出现负反馈。这种情况有时被称为失相，但该术语也用于表示其他相位分离，如 "90°失相"。负反馈可用于纠正输出误差或使系统对不需要的波动脱敏。在反馈放大器中，这种校正一般是为了减少波形失真或建立一个指定的增益水平。负反馈放大器的增益的一般表达式是渐进增益模型。
In [[biology|biological]] systems such as [[organism]]s, [[ecosystem]]s, or the [[biosphere]], most parameters must stay under control within a narrow range around a certain optimal level under certain environmental conditions. The deviation of the optimal value of the controlled parameter can result from the changes in internal and external environments. A change of some of the environmental conditions may also require change of that range to change for the system to function. The value of the parameter to maintain is recorded by a reception system and conveyed to a regulation module via an information channel. An example of this is [[insulin oscillation]]s.
In [[biology|biological]] systems such as [[organism]]s, [[ecosystem]]s, or the [[biosphere]], most parameters must stay under control within a narrow range around a certain optimal level under certain environmental conditions. The deviation of the optimal value of the controlled parameter can result from the changes in internal and external environments. A change of some of the environmental conditions may also require change of that range to change for the system to function. The value of the parameter to maintain is recorded by a reception system and conveyed to a regulation module via an information channel. An example of this is [[insulin oscillation]]s.
在[[生物学|生物]]系统中，如[[生物]]、[[生态系统]]或[[生物圈]]等，在一定的环境条件下，大多数参数必须保持在围绕某一最佳水平的狭小范围内受控。受控参数最佳值的偏离可能是由于内外环境的变化造成的。一些环境条件的改变，也可能要求改变该范围，以改变系统的功能。要保持的参数值由接收系统记录，并通过信息通道传达给调节模块。这方面的一个例子是[[胰岛素振荡]]s。
Biological systems contain many types of regulatory circuits, both positive and negative. As in other contexts, ''positive'' and ''negative'' do not imply that the feedback causes ''good'' or ''bad'' effects. A negative feedback loop is one that tends to slow down a process, whereas the positive feedback loop tends to accelerate it. The [[mirror neuron]]s are part of a social feedback system, when an observed action is "mirrored" by the brain—like a self-performed action.
Biological systems contain many types of regulatory circuits, both positive and negative. As in other contexts, ''positive'' and ''negative'' do not imply that the feedback causes ''good'' or ''bad'' effects. A negative feedback loop is one that tends to slow down a process, whereas the positive feedback loop tends to accelerate it. The [[mirror neuron]]s are part of a social feedback system, when an observed action is "mirrored" by the brain—like a self-performed action.
生物系统包含许多类型的调节回路，包括正向和负向。与其他情况一样，''正''和''负''并不意味着反馈导致''好''或''坏''效应。负反馈环路是倾向于减缓一个过程，而正反馈环路则倾向于加速它。镜像神经元]]是社会反馈系统的一部分，当一个观察到的动作被大脑 "镜像"，就像一个自我执行的动作。
Positive feedback occurs when the fed-back signal is in phase with the input signal. Under certain gain conditions, positive feedback reinforces the input signal to the point where the output of the device oscillates between its maximum and minimum possible states. Positive feedback may also introduce hysteresis into a circuit. This can cause the circuit to ignore small signals and respond only to large ones. It is sometimes used to eliminate noise from a digital signal. Under some circumstances, positive feedback may cause a device to latch, i.e., to reach a condition in which the output is locked to its maximum or minimum state. This fact is very widely used in digital electronics to make bistable circuits for volatile storage of information.
Positive feedback occurs when the fed-back signal is in phase with the input signal. Under certain gain conditions, positive feedback reinforces the input signal to the point where the output of the device oscillates between its maximum and minimum possible states. Positive feedback may also introduce hysteresis into a circuit. This can cause the circuit to ignore small signals and respond only to large ones. It is sometimes used to eliminate noise from a digital signal. Under some circumstances, positive feedback may cause a device to latch, i.e., to reach a condition in which the output is locked to its maximum or minimum state. This fact is very widely used in digital electronics to make bistable circuits for volatile storage of information.
当反馈信号与输入信号同相时，就会产生正反馈。在一定的增益条件下，正反馈增强输入信号，使器件的输出在其最大和最小可能状态之间振荡。正反馈也可能在电路中引入滞后现象。这会导致电路忽略小信号，只响应大信号。它有时被用来消除数字信号中的噪声。在某些情况下，正反馈可能导致设备闭锁，即，达到输出锁定到其最大或最小状态的条件。这个事实在数字电子产品中被广泛应用，用于信息的易失性存储。
The loud squeals that sometimes occurs in audio systems, PA systems, and rock music are known as audio feedback. If a microphone is in front of a loudspeaker that it is connected to, sound that the microphone picks up comes out of the speaker, and is picked up by the microphone and re-amplified. If the loop gain is sufficient, howling or squealing at the maximum power of the amplifier is possible.
The loud squeals that sometimes occurs in audio systems, PA systems, and rock music are known as audio feedback. If a microphone is in front of a loudspeaker that it is connected to, sound that the microphone picks up comes out of the speaker, and is picked up by the microphone and re-amplified. If the loop gain is sufficient, howling or squealing at the maximum power of the amplifier is possible.
音响系统、扩音系统和摇滚音乐中有时会出现的响亮的尖叫声，这就是所谓的音频反馈。如果话筒在它所连接的扬声器前，话筒拾取的声音就会从扬声器中传出，并被话筒拾取并重新放大。 如果环路增益足够，在功放的最大功率下，就可以发出嚎叫或尖叫声。
In an injured or infected tissue, inflammatory mediators elicit feedback responses in cells, which alter gene expression, and change the groups of molecules expressed and secreted, including molecules that induce diverse cells to cooperate and restore tissue structure and function. This type of feedback is important because it enables coordination of immune responses and recovery from infections and injuries. During cancer, key elements of this feedback fail. This disrupts tissue function and immunity.<ref>{{cite journal | last1 = Vlahopoulos | first1 = SA | title = Aberrant control of NF-κB in cancer permits transcriptional and phenotypic plasticity, to curtail dependence on host tissue: molecular mode. | journal = Cancer Biology & Medicine | date = August 2017 | pmid = 28884042 | doi = 10.20892/j.issn.2095-3941.2017.0029 | volume = 14 | issue = 3 | pages = 254–270 | pmc = 5570602}}</ref><ref>{{cite journal|last1=Korneev|first1=KV|last2=Atretkhany|first2=KN|last3=Drutskaya|first3=MS|last4=Grivennikov|first4=SI|last5=Kuprash|first5=DV|last6=Nedospasov|first6=SA|title=TLR-signaling and proinflammatory cytokines as drivers of tumorigenesis.|journal=Cytokine|date=January 2017|volume=89|pages=127–135|doi=10.1016/j.cyto.2016.01.021|pmid=26854213}}</ref>
In an injured or infected tissue, inflammatory mediators elicit feedback responses in cells, which alter gene expression, and change the groups of molecules expressed and secreted, including molecules that induce diverse cells to cooperate and restore tissue structure and function. This type of feedback is important because it enables coordination of immune responses and recovery from infections and injuries. During cancer, key elements of this feedback fail. This disrupts tissue function and immunity.<ref>{{cite journal | last1 = Vlahopoulos | first1 = SA | title = Aberrant control of NF-κB in cancer permits transcriptional and phenotypic plasticity, to curtail dependence on host tissue: molecular mode. | journal = Cancer Biology & Medicine | date = August 2017 | pmid = 28884042 | doi = 10.20892/j.issn.2095-3941.2017.0029 | volume = 14 | issue = 3 | pages = 254–270 | pmc = 5570602}}</ref><ref>{{cite journal|last1=Korneev|first1=KV|last2=Atretkhany|first2=KN|last3=Drutskaya|first3=MS|last4=Grivennikov|first4=SI|last5=Kuprash|first5=DV|last6=Nedospasov|first6=SA|title=TLR-signaling and proinflammatory cytokines as drivers of tumorigenesis.|journal=Cytokine|date=January 2017|volume=89|pages=127–135|doi=10.1016/j.cyto.2016.01.021|pmid=26854213}}</ref>
An electronic oscillator is an electronic circuit that produces a periodic, oscillating electronic signal, often a sine wave or a square wave. Oscillators convert direct current (DC) from a power supply to an alternating current signal. They are widely used in many electronic devices. Common examples of signals generated by oscillators include signals broadcast by radio and television transmitters, clock signals that regulate computers and quartz clocks, and the sounds produced by electronic beepers and video games.
An electronic oscillator is an electronic circuit that produces a periodic, oscillating electronic signal, often a sine wave or a square wave. Oscillators convert direct current (DC) from a power supply to an alternating current signal. They are widely used in many electronic devices. Common examples of signals generated by oscillators include signals broadcast by radio and television transmitters, clock signals that regulate computers and quartz clocks, and the sounds produced by electronic beepers and video games.
电子振荡器是一种电子电路，它能产生周期性的、振荡的电子信号，通常是正弦波或方波。振荡器将电源中的直流电（DC）转换为交流电信号。 它们被广泛应用于许多电子设备中。 振荡器产生的信号的常见例子包括无线电和电视发射机广播的信号，调节计算机和石英钟的时钟信号，以及电子蜂鸣器和视频游戏产生的声音。
A latch or a flip-flop is a circuit that has two stable states and can be used to store state information. They typically constructed using feedback that crosses over between two arms of the circuit, to provide the circuit with a state. The circuit can be made to change state by signals applied to one or more control inputs and will have one or two outputs. It is the basic storage element in sequential logic. Latches and flip-flops are fundamental building blocks of digital electronics systems used in computers, communications, and many other types of systems.
A latch or a flip-flop is a circuit that has two stable states and can be used to store state information. They typically constructed using feedback that crosses over between two arms of the circuit, to provide the circuit with a state. The circuit can be made to change state by signals applied to one or more control inputs and will have one or two outputs. It is the basic storage element in sequential logic. Latches and flip-flops are fundamental building blocks of digital electronics systems used in computers, communications, and many other types of systems.
锁存器或触发器是具有两个稳定状态的电路，可用于存储状态信息。它们通常利用电路的两个臂之间交叉的反馈来构造，为电路提供状态。该电路可以通过施加到一个或多个控制输入的信号来改变状态，并将有一个或两个输出。它是时序逻辑电路的基本存储元素。锁存器和触发器是用于计算机、通信和许多其他类型系统的数字电子系统的基本构件。
Latches and flip-flops are used as data storage elements. Such data storage can be used for storage of state, and such a circuit is described as sequential logic. When used in a finite-state machine, the output and next state depend not only on its current input, but also on its current state (and hence, previous inputs). It can also be used for counting of pulses, and for synchronizing variably-timed input signals to some reference timing signal.
Latches and flip-flops are used as data storage elements. Such data storage can be used for storage of state, and such a circuit is described as sequential logic. When used in a finite-state machine, the output and next state depend not only on its current input, but also on its current state (and hence, previous inputs). It can also be used for counting of pulses, and for synchronizing variably-timed input signals to some reference timing signal.
锁存器和触发器用作数据存储元件。这样的数据存储可以用来存储状态，这样的电路被描述为时序逻辑电路。当用于有限状态机时，输出和下一状态不仅取决于其当前输入，还取决于其当前状态(因此，以前的输入)。它也可以用于计数脉冲，并用于同步一些参考定时信号的变时输入信号。
锁存器和触发器用作数据存储元件。这样的数据存储可以用来存储状态，这样的电路被描述为时序逻辑电路。当用于有限状态机时，输出和下一状态不仅取决于其当前输入，还取决于其当前状态(因而也取决于以前的输入)。它也可用于脉冲的计数，以及将可变时序的输入信号同步到某个参考时序信号。
===Climate science===
===Climate science===
气候科学
Using this terminology, a latch is level-sensitive, whereas a flip-flop is edge-sensitive. That is, when a latch is enabled it becomes transparent, while a flip flop's output only changes on a single type (positive going or negative going) of clock edge.
Using this terminology, a latch is level-sensitive, whereas a flip-flop is edge-sensitive. That is, when a latch is enabled it becomes transparent, while a flip flop's output only changes on a single type (positive going or negative going) of clock edge.
{{Main|Climate change feedback}}
{{Main|Climate change feedback}}
{{主要|气候变化反馈}}
Feedback loops provide generic mechanisms for controlling the running, maintenance, and evolution of software and computing systems. Feedback-loops are important models in the engineering of adaptive software, as they define the behaviour of the interactions among the control elements over the adaptation process, to guarantee system properties at run-time. Feedback loops and foundations of control theory have been successfully applied to computing systems. In particular, they have been applied to the development of products such as IBM's Universal Database server and IBM Tivoli. From a software perspective, the autonomic (MAPE, monitor analyze plan execute) loop proposed by researchers of IBM is another valuable contribution to the application of feedback loops to the control of dynamic properties and the design and evolution of autonomic software systems.
Feedback loops provide generic mechanisms for controlling the running, maintenance, and evolution of software and computing systems. Feedback-loops are important models in the engineering of adaptive software, as they define the behaviour of the interactions among the control elements over the adaptation process, to guarantee system properties at run-time. Feedback loops and foundations of control theory have been successfully applied to computing systems. In particular, they have been applied to the development of products such as IBM's Universal Database server and IBM Tivoli. From a software perspective, the autonomic (MAPE, monitor analyze plan execute) loop proposed by researchers of IBM is another valuable contribution to the application of feedback loops to the control of dynamic properties and the design and evolution of autonomic software systems.
反馈回路为控制软件和计算系统的运行、维护和进化提供了通用机制。反馈回路是自适应软件工程中的重要模型，它定义了自适应过程中控制元件之间相互作用的行为，以保证系统在运行时的性能。反馈环路和控制理论的基础已成功地应用于计算系统。特别是，它们已经应用于产品的开发，如 IBM 的 Universal Database server 和 IBM Tivoli。从软件的角度来看，IBM 研究人员提出的自主(MAPE，monitor analyze plan execute)回路是对反馈回路应用于动态特性控制和自主软件系统设计与演化的另一个有价值的贡献。
反馈回路为控制软件和计算系统的运行、维护和进化提供了通用机制。反馈回路是自适应软件工程中的重要模型，它定义了自适应过程中控制元件之间相互作用的行为，以保证系统在运行时的性能。反馈环路和控制理论的基础已成功地应用于计算系统。特别是，它们已经应用于产品的开发，如 IBM 的 Universal Database server 和 IBM Tivoli。从软件的角度来看，IBM 研究人员提出的自主(MAPE，monitor analyze plan execute)回路是对反馈回路应用于动态特性控制和自主软件系统设计与演化的又一宝贵贡献。
===Control theory===
===Control theory===
控制理论
{{Main|Control theory}}
{{Main|Control theory}}
===Education===
===Education===
教育
For feedback in the educational context, see [[corrective feedback]].
For feedback in the educational context, see [[corrective feedback]].
Video feedback is the video equivalent of acoustic feedback. It involves a loop between a video camera input and a video output, e.g., a television screen or monitor. Aiming the camera at the display produces a complex video image based on the feedback.
Video feedback is the video equivalent of acoustic feedback. It involves a loop between a video camera input and a video output, e.g., a television screen or monitor. Aiming the camera at the display produces a complex video image based on the feedback.
视频反馈是相当于声音反馈的视频。 它涉及到摄像机输入和视频输出（如电视屏幕或显示器）之间的循环。将摄像机对准显示器，根据反馈信息生成复杂的视频图像。
===Mechanical engineering===
===Mechanical engineering===
机械工程
In ancient times, the [[float valve]] was used to regulate the flow of water in Greek and Roman [[water clock]]s; similar float valves are used to regulate fuel in a [[carburettor]] and also used to regulate tank water level in the [[flush toilet]].
In ancient times, the [[float valve]] was used to regulate the flow of water in Greek and Roman [[water clock]]s; similar float valves are used to regulate fuel in a [[carburettor]] and also used to regulate tank water level in the [[flush toilet]].
The stock market is an example of a system prone to oscillatory "hunting", governed by positive and negative feedback resulting from cognitive and emotional factors among market participants. For example:
The stock market is an example of a system prone to oscillatory "hunting", governed by positive and negative feedback resulting from cognitive and emotional factors among market participants. For example:
股市是一个容易出现振荡 "捕猎"的系统的例子，它受市场参与者之间的认知和情感因素所产生的正负反馈所支配。例如：
===Electronic engineering===
===Electronic engineering===
电子工程
[[File:Ideal feedback model.svg|thumb|The simplest form of a feedback amplifier can be represented by the ''ideal block diagram'' made up of [https://www.google.com/search?tbo=p&tbm=bks&q=%22A+unilateral+block+or+network+is+one+in+which+power+may+be+transmitted+in+one+direction+only.%22&num=10&gws_rd=ssl unilateral elements].<ref name="Chen">
[[File:Ideal feedback model.svg|thumb|The simplest form of a feedback amplifier can be represented by the ''ideal block diagram'' made up of [https://www.google.com/search?tbo=p&tbm=bks&q=%22A+unilateral+block+or+network+is+one+in+which+power+may+be+transmitted+in+one+direction+only.%22&num=10&gws_rd=ssl unilateral elements].<ref name="Chen">
The conventional economic equilibrium model of supply and demand supports only ideal linear negative feedback and was heavily criticized by Paul Ormerod in his book The Death of Economics, which, in turn, was criticized by traditional economists. This book was part of a change of perspective as economists started to recognise that chaos theory applied to nonlinear feedback systems including financial markets.
The conventional economic equilibrium model of supply and demand supports only ideal linear negative feedback and was heavily criticized by Paul Ormerod in his book The Death of Economics, which, in turn, was criticized by traditional economists. This book was part of a change of perspective as economists started to recognise that chaos theory applied to nonlinear feedback systems including financial markets.
传统的经济供求平衡模型只支持理想的线性负反馈，保罗·奥默罗德Paul Ormerod在其《经济学之死》一书中对其提出了严厉的批评，而传统经济学家也对其提出了批评。随着经济学家开始认识到混沌理论适用于包括金融市场在内的非线性反馈系统，这本书是观点转变的一部分。
{{cite book|title=Circuit Analysis and Feedback Amplifier Theory|author=Wai-Kai Chen|publisher=CRC Press|year=2005|isbn=9781420037272|location=423825181|pages=13–1|chapter=Chapter 13: General feedback theory|quote=[In a practical amplifier] the forward path may not be strictly unilateral, the feedback path is usually bilateral, and the input and output coupling networks are often complicated.|chapter-url=https://books.google.com/books?id=ZlJM1OLDQx0C&pg=SA13-PA1}}
{{cite book|title=Circuit Analysis and Feedback Amplifier Theory|author=Wai-Kai Chen|publisher=CRC Press|year=2005|isbn=9781420037272|location=423825181|pages=13–1|chapter=Chapter 13: General feedback theory|quote=[In a practical amplifier] the forward path may not be strictly unilateral, the feedback path is usually bilateral, and the input and output coupling networks are often complicated.|chapter-url=https://books.google.com/books?id=ZlJM1OLDQx0C&pg=SA13-PA1}}
====Negative feedback====
====Negative feedback====
负反馈
A Negative feedback occurs when the fed-back output signal has a relative phase of 180° with respect to the input signal (upside down). This situation is sometimes referred to as being ''out of phase'', but that term also is used to indicate other phase separations, as in "90° out of phase". Negative feedback can be used to correct output errors or to desensitize a system to unwanted fluctuations.<ref name=Bhattacharya>
A Negative feedback occurs when the fed-back output signal has a relative phase of 180° with respect to the input signal (upside down). This situation is sometimes referred to as being ''out of phase'', but that term also is used to indicate other phase separations, as in "90° out of phase". Negative feedback can be used to correct output errors or to desensitize a system to unwanted fluctuations.<ref name=Bhattacharya>
当反馈的输出信号与输入信号的相对相位为180°（上下颠倒）时，就会出现负反馈。这种情况有时被称为''失相''，但该术语也用于表示其他相位分离，如 "90°失相"。负反馈可用于纠正输出误差或使系统对不需要的波动失去敏感度。
For an analysis of desensitization in the system pictured, see {{cite book |author=S.K Bhattacharya |title=Linear Control Systems |pages=134–135 |quote=The parameters of a system ... may vary... The primary advantage of using feedback in control systems is to reduce the system's sensitivity to parameter variations. |chapter=§5.3.1 Effect of feedback on parameter variations |isbn=9788131759523 |publisher=Pearson Education India |year=2011 |chapter-url=https://books.google.com/books?id=e5Z1A_6jxAUC&q=%22primary+advantage+of+using+feedback+in+control+system+is+to+reduce+the+system%27s+sensitivity+to+parameter+variations%22&pg=PA135}}
For an analysis of desensitization in the system pictured, see {{cite book |author=S.K Bhattacharya |title=Linear Control Systems |pages=134–135 |quote=The parameters of a system ... may vary... The primary advantage of using feedback in control systems is to reduce the system's sensitivity to parameter variations. |chapter=§5.3.1 Effect of feedback on parameter variations |isbn=9788131759523 |publisher=Pearson Education India |year=2011 |chapter-url=https://books.google.com/books?id=e5Z1A_6jxAUC&q=%22primary+advantage+of+using+feedback+in+control+system+is+to+reduce+the+system%27s+sensitivity+to+parameter+variations%22&pg=PA135}}
====Positive feedback====
====Positive feedback====
正反馈
Positive feedback occurs when the fed-back signal is in phase with the input signal. Under certain gain conditions, positive feedback reinforces the input signal to the point where the output of the device [[oscillates]] between its maximum and minimum possible states. Positive feedback may also introduce [[hysteresis]] into a circuit. This can cause the circuit to ignore small signals and respond only to large ones. It is sometimes used to eliminate noise from a digital signal. Under some circumstances, positive feedback may cause a device to latch, i.e., to reach a condition in which the output is locked to its maximum or minimum state. This fact is very widely used in digital electronics to make [[Flip-flop (electronics)|bistable]] circuits for volatile storage of information.
Positive feedback occurs when the fed-back signal is in phase with the input signal. Under certain gain conditions, positive feedback reinforces the input signal to the point where the output of the device [[oscillates]] between its maximum and minimum possible states. Positive feedback may also introduce [[hysteresis]] into a circuit. This can cause the circuit to ignore small signals and respond only to large ones. It is sometimes used to eliminate noise from a digital signal. Under some circumstances, positive feedback may cause a device to latch, i.e., to reach a condition in which the output is locked to its maximum or minimum state. This fact is very widely used in digital electronics to make [[Flip-flop (electronics)|bistable]] circuits for volatile storage of information.
当反馈信号与输入信号同相时，就会出现正反馈。在某些增益条件下，正反馈会强化输入信号，使器件的输出在其最大和最小可能状态之间[[振荡]]。正反馈还可以将[[滞后]]引入电路。这可能导致电路忽略小信号，只对大信号作出反应。它有时用于消除数字信号中的噪声。在某些情况下，正反馈可能会导致器件锁存，即达到输出被锁定在其最大或最小状态的条件。这一事实在数字电子学中被非常广泛地用于制作[[触发器(电子学)|双稳态]]电路，用于信息的易失性存储。
The loud squeals that sometimes occurs in [[audio system]]s, [[public address system|PA systems]], and [[rock music]] are known as [[audio feedback]]. If a microphone is in front of a loudspeaker that it is connected to, sound that the microphone picks up comes out of the speaker, and is picked up by the microphone and re-amplified. If the [[loop gain]] is sufficient, howling or squealing at the maximum power of the amplifier is possible.
The loud squeals that sometimes occurs in [[audio system]]s, [[public address system|PA systems]], and [[rock music]] are known as [[audio feedback]]. If a microphone is in front of a loudspeaker that it is connected to, sound that the microphone picks up comes out of the speaker, and is picked up by the microphone and re-amplified. If the [[loop gain]] is sufficient, howling or squealing at the maximum power of the amplifier is possible.
在[[音响系统]]、[[公共广播系统|PA系统]]和[[摇滚音乐]]中有时会出现的响亮的尖叫声被称为[[音频反馈]]。如果话筒在它所连接的扬声器前，话筒拾取到的声音就会从扬声器中发出，并被话筒拾取并重新放大。 如果[[环路增益]]足够，则可以在放大器的最大功率下发出嚎叫或尖叫声。
====Oscillator====
====Oscillator====
振荡器
[[File:OpAmpHystereticOscillator.svg|thumb|A popular [[Relaxation oscillator#Comparator–based electronic relaxation oscillator|op-amp relaxation oscillator]].]]
[[File:OpAmpHystereticOscillator.svg|thumb|A popular [[Relaxation oscillator#Comparator–based electronic relaxation oscillator|op-amp relaxation oscillator]].]]
An [[electronic oscillator]] is an [[electronic circuit]] that produces a periodic, [[oscillation|oscillating]] electronic signal, often a [[sine wave]] or a [[square wave]].<ref name="Snelgrove">{{cite encyclopedia
An [[electronic oscillator]] is an [[electronic circuit]] that produces a periodic, [[oscillation|oscillating]] electronic signal, often a [[sine wave]] or a [[square wave]].<ref name="Snelgrove">{{cite encyclopedia
电子振荡器]]是一种[[电子电路]]，能产生周期性的[[振荡|振荡]]电子信号，通常是[[正弦波]]或[[方波]]。
| last = Snelgrove
| last = Snelgrove