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Feedback

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."

History
Self-regulating mechanisms have existed since antiquity, and the idea of feedback 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.

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.

Centrifugal governors were used to regulate the distance and pressure between millstones in windmills since the 17th century. In 1788, James Watt designed his first centrifugal governor following a suggestion from his business partner Matthew Boulton, for use in the steam engines of their production. Early steam engines employed a purely reciprocating motion, and were used for pumping water – an application that could tolerate variations in the working speed, but the use of steam engines for other applications called for more precise control of the speed.

In 1868, James Clerk Maxwell wrote a famous paper, "On governors", that is widely considered a classic in feedback control theory. This was a landmark paper on control theory and the mathematics of feedback.

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.

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.

The development of cybernetics from the 1940s onwards was centred around the study of circular causal feedback mechanisms.

Over the years there has been some dispute as to the best definition of feedback. According to cybernetician 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. "[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."

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.

Positive and negative feedback
Positive feedback: If the signal feedback from output is in phase with the input signal, the feedback is called positive feedback.

Negative feedback: If the signal feedback is out of phase by 180° with respect to the input signal, the feedback is called negative feedback.

As an example of negative feedback, the diagram might represent a cruise control system in a car 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 difference of the speed as measured by the speedometer from the target speed (set point). The controller interprets the speed 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 change of road grade to reduce the error in speed, minimising the changing slope.

The terms "positive" and "negative" were first applied to feedback prior to WWII. The idea of positive feedback already existed in the 1920s when the regenerative circuit was made. Friis and Jensen (1924) described this circuit 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 mentioned only in passing. Harold Stephen Black's classic 1934 paper first details the use of negative feedback in electronic amplifiers. According to Black:

"Positive feed-back increases the gain of the amplifier, negative feed-back reduces it." According to Mindell (2002) confusion in the terms arose shortly after this: "...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."

Even before these terms were being used, James Clerk Maxwell had described their concept through several kinds of "component motions" associated with the centrifugal governors used in steam engines. He distinguished those that lead to a continued increase in a disturbance or the amplitude of a wave or oscillation, from those that lead to a decrease of the same quality.

Terminology
The terms positive and negative feedback are defined in different ways within different disciplines.

 * 1) the change of the gap between reference and actual values of a parameter or trait, based on whether the gap is widening (positive) or narrowing (negative).
 * 2) the valence of the action or effect that alters the gap, based on whether it makes the recipient or observer happy (positive) or unhappy (negative).

The two definitions may be confusing, like when an incentive (reward) is used to boost poor performance (narrow a gap). Referring to definition 1, some authors use alternative terms, replacing positive and negative with self-reinforcing and self-correcting, reinforcing and balancing, discrepancy-enhancing and discrepancy-reducing or regenerative and degenerative respectively. And for definition 2, some authors promote describing the action or effect as positive and negative reinforcement or punishment rather than feedback. 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.

This confusion may arise because feedback can be used to provide information or motivate, and often has both a qualitative and a quantitative component. As Connellan and Zemke (1993) put it: "Quantitative feedback tells us how much and how many. Qualitative feedback tells us how good, bad or indifferent."

Limitations of negative and positive feedback
While simple systems can sometimes be described as one or the other type, many systems with feedback loops cannot be shoehorned into either type, and this is especially true when multiple loops are present.

"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."

Other types of feedback
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.

The term bipolar feedback has been coined to refer to biological systems where positive and negative feedback systems can interact, the output of one affecting the input of another, and vice versa.

Some systems with feedback can have very complex behaviors such as 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.

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.

Mathematics and dynamical systems

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.

Physics
Physical systems present feedback through the mutual interactions of its parts. Feedback is also relevant for the regulation of experimental conditions, noise reduction, and signal control. The thermodynamics of feedback-controlled systems has intrigued physicist since the Maxwell's demon, with recent advances on the consequences for entropy reduction and performance increase.

Biology
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.

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.

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. 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.

Mechanisms of feedback were first elucidated in bacteria, where a nutrient elicits changes in some of their metabolic functions. 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 François 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).

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.

In zymology, feedback serves as regulation of activity of an enzyme by its direct product(s) or downstream metabolite(s) in the metabolic pathway (see Allosteric regulation).

The hypothalamic–pituitary–adrenal axis is largely controlled by positive and negative feedback, much of which is still unknown.

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.

Climate science
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.

Control theory
Feedback is extensively used in control theory, using a variety of methods including state space (controls), full state feedback, and so forth. In the context of control theory, "feedback" is traditionally assumed to specify "negative feedback".

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.

Education
For feedback in the educational context, see corrective feedback.

Mechanical engineering
In ancient times, the float valve was used to regulate the flow of water in Greek and Roman water clocks; similar float valves are used to regulate fuel in a carburettor and also used to regulate tank water level in the flush toilet.

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 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 Great Eastern was one of the largest steamships of its time and employed a steam powered rudder with feedback mechanism designed in 1866 by John McFarlane Gray. Joseph Farcot coined the word servo in 1873 to describe steam-powered steering systems. Hydraulic servos were later used to position guns. Elmer Ambrose Sperry of the Sperry Corporation designed the first autopilot in 1912. Nicolas Minorsky published a theoretical analysis of automatic ship steering in 1922 and described the PID controller.

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.

Electronic engineering

The use of feedback is widespread in the design of electronic components such as amplifiers, oscillators, and stateful logic circuit elements such as flip-flops and counters. Electronic feedback systems are also very commonly used to control mechanical, thermal and other physical processes.

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.

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.

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.

When two or more amplifiers are cross-coupled using positive feedback, complex behaviors can be created. These multivibrators are widely used and include:
 * astable circuits, which act as oscillators
 * monostable circuits, which can be pushed into a state, and will return to the stable state after some time
 * bistable circuits, which have two stable states that the circuit can be switched between

Negative feedback
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.

Positive feedback
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.

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.

Oscillator
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.

Oscillators are often characterized by the frequency of their output signal:
 * A low-frequency oscillator (LFO) is an electronic oscillator that generates a frequency below ≈20 Hz. This term is typically used in the field of audio synthesizers, to distinguish it from an audio frequency oscillator.
 * An audio oscillator produces frequencies in the audio range, about 16 Hz to 20 kHz.
 * An RF oscillator produces signals in the radio frequency (RF) range of about 100 kHz to 100 GHz.

Oscillators designed to produce a high-power AC output from a DC supply are usually called inverters.

There are two main types of electronic oscillator: the linear or harmonic oscillator and the nonlinear or relaxation oscillator.

Latches and flip-flops

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.

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.

Flip-flops can be either simple (transparent or opaque) or clocked (synchronous or edge-triggered). Although the term flip-flop has historically referred generically to both simple and clocked circuits, in modern usage it is common to reserve the term flip-flop exclusively for discussing clocked circuits; the simple ones are commonly called latches.

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.

Software
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 Db2 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.

User interface design
Feedback is also a useful design principle for designing user interfaces.

Video 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.

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/

title: Feedback


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Furigana

Furigana (振り仮名) is a Japanese reading aid consisting of smaller kana (syllabic characters) printed either above or next to kanji (logographic characters) or other characters to indicate their pronunciation. It is one type of ruby text. Furigana is also known as yomigana (読み仮名) and rubi (ルビ) in Japanese. In modern Japanese, it is usually used to gloss rare kanji, to clarify rare, nonstandard or ambiguous kanji readings, or in children's or learners' materials. Before the post-World War II script reforms, it was more widespread.

Furigana is most often written in hiragana, though in certain cases it may be written in katakana, Roman alphabet letters or in other, simpler kanji. In vertical text, tategaki, the furigana is placed to the right of the line of text; in horizontal text, yokogaki, it is placed above the line of text, as illustrated below.

or

These examples spell the word nihongo, which is made up of three kanji characters: 日 (ni, written in hiragana as に), 本 (hon, written in hiragana as ほん) and 語 (go, written in hiragana as ご).

Appearance
Furigana may be added by character, in which case the furigana character(s) that correspond to a kanji are centered over that kanji; or by word or phrase, in which case the entire furigana text is centered over several kanji characters, even if the kanji do not represent equal shares of the kana needed to write them. The latter method is more common, especially since some words in Japanese have unique pronunciations (jukujikun) that are not related to readings of any of the characters the word is written with.

Furigana fonts are generally sized so that two kana characters fit naturally over one kanji; when more kana are required, this is resolved either by adjusting the furigana by using a condensed font (narrowing the kana), or by adjusting the kanji by intercharacter spacing (adding spaces around the kanji). In case an isolated kanji character has a long reading—for example 〜に携わる (where 携 reads たずさ, tazusa)—the furigana may instead spill over into the space next to the neighboring kana characters, without condensing or changing spacing. Three-kana readings are not uncommon, particularly due to yōon with a long vowel, such as ryō (りょう); five kana are required for kokorozashi (志、こころざし) and six for uketamawaru (承る、うけたまわる), the longest of any character in the Joyo kanji. Very long readings also occur for certain kanji or symbols which have a gairaigo (loan word) reading; the word "centimeter" is generally written as "cm" (with two half-width characters, so occupying one space) and has the seven-kana reading センチメートル (senchimētoru) (it can also be written as the kanji 糎, though this is very rare); another common example is "%" (the percent sign), which has the five kana reading パーセント (pāsento). These cause severe spacing problems due to length and these words being used as units (hence closely associated with the preceding figure).

When it is necessary to distinguish between native Japanese kun'yomi pronunciations and Chinese-derived on'yomi pronunciations, for example in kanji dictionaries, the kun'yomi pronunciations are written in hiragana, and the on'yomi pronunciations are written in katakana. However, this distinction is really only important in dictionaries and other reference works. In ordinary prose, the script chosen will usually be hiragana. The one general exception to this is modern Chinese place names, personal names, and (occasionally) food names—these will often be written with kanji, and katakana used for the furigana; in more casual writing these are simply written in katakana, as borrowed words. Occasionally this style is also used for loanwords from other languages (especially English). For example, the kanji 一角獣 (literally "one horn beast") might be glossed with katakana ユニコーン, yunikōn, to show the pronunciation of the loanword "unicorn", which is unrelated to the normal reading of the kanji. Generally, though, such loanwords are just written in straight katakana.

The distinction between regular kana and the smaller character forms (yōon and sokuon), which are used in regular orthography to mark such things as gemination and palatalization, is often not made in furigana: for example, the usual hiragana spelling of the word 却下 (kyakka) is きゃっか, but in furigana it might be written きやつか. This was especially common in old-fashioned movable type printing when smaller fonts were not available. Nowadays, with computer-based printing systems, this occurs less frequently.

Alignment rules in word processing or typesetting
Various word processing or typesetting software programs, such as Microsoft Word, Adobe InDesign, Adobe InCopy, etc. have features for adding ruby text, especially Japanese furigana. Among formatting features are different rules for aligning the kana over or to the right of the base text, usually either when the base text string is longer than the furigana string or vice versa. Extra spaces may be needed depending on the size of the shorter string (either the ruby string or the base string) relatively to the longer one.
 * Centered, left/top or right/bottom: No spaces are added in between the characters. The shorter string is aligned to the center (中付きルビ nakatsuki rubi), the left/top (肩付きルビ katatsuki rubi) or the right/bottom of the longer string.
 * 1-2-1 (JIS): Spaces are added at the start of and the end of the shorter string, and in between its component characters, so that the spaces in between are twice as wide or tall as the spaces at the start and at the end. Space width or height is calculated based on the width or height of the square bounding box of a glyph (Japanese typefaces are generally monospaced). The strings are still, in essence, aligned to the center of each other, rather than to the left/top or right/bottom.
 * 0-1-0: Equal spaces are added, similarly to the 1-2-1 rule, in between the component characters of the shorter string, but not its start or end.

Usage
Furigana are most commonly used in works for children, who may not have sufficiently advanced reading skills to recognize the kanji, but can understand the word when written phonetically in hiragana. Because children learn hiragana before katakana, in books for very young children, there are hiragana－furigana next to the katakana characters. It is common to use furigana on all kanji characters in works for young children. This is called sōrubi (総ルビ) in Japanese.

Numeric characters used for counting (e.g. 二/２ ni-hon "two long things"; ２つめ futatsume "second"; 二/２ dai-ni kan "book 2"; ２ページ ni-pēji "page 2"; etc.) are usually not tagged with furigana. Exceptions include a few cases such as 一人/１人 hitori "one person" and 二人/２人 futari "two people", which may be tagged with separate kana for each character (/), or non-separated kana for the whole word (/), depending on the style of the publisher in question; or characters for numerals greater than 1,000 (千), such as 万 (10,000), 億 (100,000,000), etc. Numeric words in established compounds (e.g. ippo "step";  hitome "sight; attention"), however, are generally tagged with furigana.

Many children's manga, shōnen and shōjo manga use furigana (again however, rarely on numerals). Shōnen and shōjo manga tend to have furigana for all non-numeric characters, while some manga (such as early volumes of Doraemon and other manga published by Shogakukan), may also ignore furigana on elementary-grade kanji or easy words. Seinen and josei manga ignores furigana most of the time, even on the names of the characters if they're common names, although some publishers may still routinely use furigana for the first mentions of important characters' names in a volume or chapter. There are also books with a phonetic guide (mainly in hiragana but sometimes in rōmaji) for Japanese learners, which may be bilingual or Japanese only. These are popular with foreigners wishing to master Japanese faster and enjoy reading Japanese short stories, novels or articles.

Due to the small type used for furigana, for maximum readability, some manga publishers may use regular kana instead of small kana. For example, はっしん hasshin may be spelled はつしん *hatsushin instead.

Some websites and tools exist which provide a phonetic guide for Japanese web pages (in hiragana, rōmaji or kiriru-moji); these are popular with both Japanese children and foreign Japanese learners.

In works aimed at adult Japanese speakers, furigana may be used on a word written in uncommon kanji; in the mass media, they are generally used on words containing non-Jōyō kanji.

Furigana commonly appear alongside kanji names and their romanizations on signs for railway stations, even if the pronunciation of the kanji is commonly known. Furigana also appear often on maps to show the pronunciation of unusual place names.

Before the war, youths might arguably have been almost illiterate if not for furigana.

Names
Japanese names are usually written in kanji. Because there are many possible readings for kanji names, including special name-only readings called nanori, furigana are often used to give the readings of names. On Japanese official forms, where the name is to be written, there is always an adjacent column for the name to be written in furigana.

Furigana may also be used for foreign names written in kanji. Chinese and Korean names are the most common examples: Chinese names are usually pronounced with Japanese readings and the pronunciation written in hiragana, while Korean names are usually pronounced with Korean readings and the pronunciation written in katakana.

Language learning
Kanji and kanji compounds are often presented with furigana in Japanese-language textbooks for non-native speakers.

Furigana are also often used in foreign-language textbooks for Japanese learners to indicate pronunciation. The words are written in the original foreign script, such as hangul for Korean, and furigana is used to indicate the pronunciation. According to Ministry of Education guidelines, and the opinions of educators, the use of Japanese furigana should be avoided in English teaching due to the differences in pronunciation between English and Japanese. For instance, the word "birthdate" might be glossed in furigana as バースデイト (bāsudeito), which corresponds to an imperfect pronunciation.

Other effects
Furigana unrelated to the kanji they are assigned to are often used to convey certain effects, rather than to denote a phonetic guide, especially in manga, anime, video games, and tabletop games. This usage is known as 義訓 gikun (see also Kanji). The specific effects vary.

It may be used to visually reinforce complex ideas without having to use long expressions. For example, the word akumu "nightmare" may be annotated with しんじつ shinjitsu "truth" (i.e. ) rather than its true reading, to convey the meaning of "nightmarish truth". Some authors may even use furigana that means the opposite of what the base text does to reinforce the complicated relationship between characters. For example, shin'yū "close friend" may be annotated with  raibaru "rival", to mean "a rival who is also friend".

Another use is to indicate the meanings of ambiguous or foreign words. For example, the word (koko, "here") may be annotated with a more specific description like  byōin "hospital" (i.e. ) to mean "here (at this hospital)". Or in a work of science fiction, an astronaut may use the word furusato "my hometown", when referring to planet Earth; to clarify that for the reader, ふるさと may be written over the word  chikyū "Earth". A similar technique is used in Japanese subtitles on foreign films to associate the written Japanese with the sounds actually being spoken by the actors, or in a translation of a work of fiction to preserve the original sound of a proper name in furigana while indicating its meaning with kanji. For example, "Firebolt" in the Harry Potter series is written, composed of the kanji honō no ikazuchi "flame thunderbolt" and the furigana ファイアボルト faiaboruto.

Some manga combine the rendition of a foreign word (especially an obscure one) in furigana as the intended reading of a term, with more familiar kanji as the meaning. For example, eki "station" may be annotated with ステーション sutēshon (the rendition of the English "station") to convey a foreign, exotic feel; This is sometimes done conversely, for example, by annotating an exotic term like bēze "kiss" with a more common synonym like  kissu.

Some writers use furigana to represent slang pronunciations, particularly those that would be difficult to understand without the kanji to provide their meaning. Others use it simply to shrink kana spellings that are too long, thanks to the small type of furigana. For example, intāpōru "Interpol" may be shortened to.

In karaoke it is common for furigana to be placed on the song lyrics. The song lyrics are often written in kanji pronounced quite differently from the furigana. The furigana version is used for pronunciation.

Okurigana
Okurigana are kana that appear inline at normal size following kanji stems, typically to complete and to inflect adjectives and verbs. In this use they may also help to disambiguate kanji with multiple readings; for example, 上がる (あがる, agaru) vs. 上る (のぼる, noboru). Unlike furigana, the use of okurigana is a mandatory part of the written language.

Kunten
In the written style known as kanbun, which is the Japanese approximation of Classical Chinese, small marks called kunten are sometimes added as reading aids. Unlike furigana, which indicate pronunciation, kunten indicate Japanese grammatical structures absent from the kanbun, and also show how words should be reordered to fit Japanese sentence structure.

Furikanji
Furigana are sometimes also used to indicate meaning, rather than pronunciation. Over the foreign text, smaller-sized Japanese words, in kana or kanji, corresponding to the meaning of the foreign words, effectively translate it in place. While rare now, some late 19th–early 20th century authors used kanji as furigana for loanwords written in katakana. This usage is called furikanji (振り漢字) in Japanese, since furigana implies the use of kana. For example, リリック ririkku "lyric" may be tagged with 歌詞 kashi "lyrics" for clarification rather than for phonetic guidance.

title: Furigana


text:
Francis II, Holy Roman Emperor

Francis II and I (Franz II.; 12 February 1768 – 2 March 1835) was the last Holy Roman Emperor as Francis II from 1792 to 1806, and the first Emperor of Austria as Francis I from 1804 to 1835. He was also King of Hungary, Croatia and Bohemia, and served as the first president of the German Confederation following its establishment in 1815.

The eldest son of future Emperor Leopold II and Maria Luisa of Spain, Francis was born in Florence, where his father ruled as Grand Duke of Tuscany. Leopold became Holy Roman Emperor in 1790 but died two years later, and Francis succeeded him. His empire immediately became embroiled in the French Revolutionary Wars, the first of which ended in Austrian defeat and the loss of the left bank of the Rhine to France. After another French victory in the War of the Second Coalition, Napoleon crowned himself Emperor of the French. In response, Francis assumed the title of Emperor of Austria. He continued his leading role as Napoleon's adversary in the Napoleonic Wars, and suffered successive defeats that greatly weakened Austria as a European power. In 1806, after Napoleon created the Confederation of the Rhine, Francis abdicated as Holy Roman Emperor, which in effect marked the dissolution of the Holy Roman Empire. Following the defeat of the Fifth Coalition, Francis ceded more territory to France and was forced to wed his daughter Marie Louise to Napoleon.

In 1813, Francis turned against Napoleon and finally defeated him in the War of the Sixth Coalition, forcing the French emperor to abdicate. Austria took part as a leading member of the Holy Alliance at the Congress of Vienna, which was largely dominated by Francis' chancellor Klemens von Metternich, culminating in a new European order and the restoration of most of Francis' ancient dominions. Due to the establishment of the Concert of Europe, which resisted popular nationalist and liberal tendencies, Francis was viewed as a reactionary later in his reign. Francis died in 1835 at the age of 67 and was succeeded by his son, Ferdinand I.

Early life
Francis was a son of Emperor Leopold II (1747–1792) and his wife Maria Luisa of Spain (1745–1792), daughter of Charles III of Spain. Francis was born in Florence, the capital of Tuscany, where his father reigned as Grand Duke from 1765 to 1790. Though he had a happy childhood surrounded by his many siblings, his family knew Francis was likely to be a future Emperor (his uncle Joseph had no surviving issue from either of his two marriages), and so in 1784 the young Archduke was sent to the Imperial Court in Vienna to educate and prepare him for his future role.

Emperor Joseph II himself took charge of Francis' development. His disciplinarian regime was a stark contrast to the indulgent Florentine Court of Leopold. The Emperor wrote that Francis was "stunted in growth", "backward in bodily dexterity and deportment", and "neither more nor less than a spoiled mother's child." Joseph concluded that "the manner in which he was treated for upwards of sixteen years could not but have confirmed him in the delusion that the preservation of his own person was the only thing of importance."

Joseph's martinet method of improving the young Francis was "fear and unpleasantness." The young Archduke was isolated, the reasoning being that this would make him more self-sufficient as it was felt by Joseph that Francis "failed to lead himself, to do his own thinking." Nonetheless, Francis greatly admired his uncle, if rather in fear of him. To complete his training, Francis was sent to join an army regiment in Hungary and he settled easily into the routine of military life. He was present at the siege of Belgrade which occurred during the Austro-Turkish War.

After the death of Joseph II in 1790, Francis' father became Emperor. He had an early taste of power while acting as Leopold's deputy in Vienna while the incoming Emperor traversed the Empire attempting to win back those alienated by his brother's policies. The strain took a toll on Leopold and by the winter of 1791, he became ill. He gradually worsened throughout early 1792; on the afternoon of 1 March Leopold died, at the relatively young age of 44. Francis, just past his 24th birthday, was now Emperor, much sooner than he had expected.

Wars with France
As the head of the Holy Roman Empire and the ruler of the vast multi-ethnic Habsburg hereditary lands, Francis felt threatened by the French revolutionaries and later Napoleon's expansionism as well as their social and political reforms which were being exported throughout Europe in the wake of the conquering French armies. Francis had a fraught relationship with France. His aunt Marie Antoinette, the wife of Louis XVI and Queen consort of France, was guillotined by the revolutionaries in 1793, at the beginning of his reign, although, on the whole, he was indifferent to her fate.Later, he led the Holy Roman Empire into the French Revolutionary Wars. He briefly commanded the Allied forces during the Flanders Campaign of 1794 before handing over command to his brother Archduke Charles. He was later defeated by Napoleon. By the Treaty of Campo Formio, he ceded the left bank of the Rhine to France in exchange for Venice and Dalmatia. He again fought against France during the War of the Second Coalition.

On 11 August 1804, in response to Napoleon crowning himself as emperor of the French earlier that year, he announced that he would henceforth assume the title of hereditary emperor of Austria as Francis I, a move that technically was illegal in terms of imperial law. Yet Napoleon had agreed beforehand and therefore it happened.

Napoleonic Wars
During the War of the Third Coalition, the Austrian forces met a crushing defeat at Austerlitz, and Francis had to agree to the Treaty of Pressburg, which greatly weakened Austria and brought about the final collapse of the Holy Roman Empire. In July 1806, under massive pressure from France, Bavaria and fifteen other German states ratified the statutes founding the Confederation of the Rhine, with Napoleon designated Protector, and they announced to the Imperial Diet their intention to leave the Empire with immediate effect. Then, on 22 July, Napoleon issued an ultimatum to Francis demanding that he abdicate as Holy Roman Emperor by 10 August.

Five days later, Francis bowed to the inevitable and, without mentioning the ultimatum, affirmed that since the Peace of Pressburg he had tried his best to fulfil his duties as emperor but that circumstances had convinced him that he could no longer rule according to his oath of office, the formation of the Confederation of the Rhine making that impossible. He added that "we hereby decree that we regard the bond which until now tied us to the states of the Empire as dissolved" in effect dissolving the empire. At the same time he declared the complete and formal withdrawal of his hereditary lands from imperial jurisdiction. After that date, he reigned as Francis I, Emperor of Austria.

In 1809, Francis attacked France again, hoping to take advantage of the Peninsular War embroiling Napoleon in Spain. He was again defeated, and this time forced to ally himself with Napoleon, ceding territory to the Empire, joining the Continental System, and wedding his daughter Marie-Louise to the Emperor. The Napoleonic wars drastically weakened Austria, making it entirely landlocked and threatened its preeminence among the states of Germany, a position that it would eventually cede to the Kingdom of Prussia.

In 1813, for the fifth and final time, Austria turned against France and joined Great Britain, Russia, Prussia and Sweden in their war against Napoleon. Austria played a major role in the final defeat of France—in recognition of this, Francis, represented by Clemens von Metternich, presided over the Congress of Vienna, helping to form the Concert of Europe and the Holy Alliance, ushering in an era of conservatism in Europe. The German Confederation, a loose association of Central European states was created by the Congress of Vienna in 1815 to organize the surviving states of the Holy Roman Empire. The Congress was a personal triumph for Francis, who hosted the assorted dignitaries in comfort, though Francis undermined his allies Tsar Alexander and Frederick William III of Prussia by negotiating a secret treaty with the restored French king Louis XVIII.

Domestic policy

The violent events of the French Revolution impressed themselves deeply into the mind of Francis (as well as all other European monarchs), and he came to distrust radicalism in any form. In 1794, a "Jacobin" conspiracy was discovered in the Austrian and Hungarian armies. The leaders were put on trial, but the verdicts only skirted the perimeter of the conspiracy. Francis' brother Alexander Leopold (at that time Palatine of Hungary) wrote to the Emperor admitting "Although we have caught a lot of the culprits, we have not really got to the bottom of this business yet." Nonetheless, two officers heavily implicated in the conspiracy were hanged and gibbeted, while numerous others were sentenced to imprisonment (many of whom died from the conditions)

Francis was from his experiences suspicious and set up an extensive network of police spies and censors to monitor dissent (in this he was following his father's lead, as the Grand Duchy of Tuscany had the most effective secret police in Europe). Even his family did not escape attention. His brothers, the Archdukes Charles and Johann had their meetings and activities spied upon. Censorship was also prevalent. The author Franz Grillparzer, a Habsburg patriot, had one play suppressed solely as a "precautionary" measure. When Grillparzer met the censor responsible, he asked him what was objectionable about the work. The censor replied, "Oh, nothing at all. But I thought to myself, 'One can never tell'."

In military affairs Francis had allowed his brother, the Archduke Charles, extensive control over the army during the Napoleonic wars. Yet, distrustful of allowing any individual too much power, he otherwise maintained the separation of command functions between the Hofkriegsrat and his field commanders. In the later years of his reign he limited military spending, requiring it not exceed forty million florins per year; because of inflation this resulted in inadequate funding, with the army's share of the budget shrinking from half in 1817 to only twenty-three percent in 1830.

Francis presented himself as an open and approachable monarch (he regularly set aside two mornings each week to meet with his imperial subjects, regardless of status, by appointment in his office, even speaking to them in their own language), but his will was sovereign. In 1804, he had no compunction about announcing that through his authority as Holy Roman Emperor, he declared he was now Emperor of Austria (at the time a geographical term that had little resonance). Two years later, Francis personally wound up the moribund Holy Roman Empire of the German Nation. Both actions were of dubious constitutional legality.

To increase patriotic sentiment during the war with France, the anthem "Gott erhalte Franz den Kaiser" was composed in 1797 to be sung as the Kaiserhymne to music by Joseph Haydn. The lyrics were adapted for later Emperors and the music lives on as the German national anthem "Deutschlandlied".

Death
On 2 March 1835, 43 years and a day after his father's death, Francis died in Vienna of a sudden fever aged 67, in the presence of many of his family and with all the religious comforts. His funeral was magnificent, with his Viennese subjects respectfully filing past his coffin in the court chapel of the Hofburg palace for three days. Francis was interred in the traditional resting place of Habsburg monarchs, the Imperial Crypt in Vienna's Neue Markt Square. He is buried in tomb number 57, surrounded by tombs of his four wives.Francis passed on a main point in the political testament he left for his son and heir Ferdinand: to "preserve unity in the family and regard it as one of the highest goods." In many portraits (particularly those painted by Peter Fendi) he was portrayed as the patriarch of a loving family, surrounded by his children and grandchildren.

Marriages
Francis II married four times:

 * 1) On 6 January 1788, to Elisabeth of Württemberg (21 April 1767 – 18 February 1790).
 * 2) On 15 September 1790, to his double first cousin Maria Teresa of the Two Sicilies (6 June 1772 – 13 April 1807), daughter of King Ferdinand I of the Two Sicilies (both were grandchildren of Empress Maria Theresa and shared all of their other grandparents in common), with whom he had twelve children, of whom only seven reached adulthood.
 * 3) On 6 January 1808, he married again to another first cousin, Maria Ludovika of Austria-Este (14 December 1787 – 7 April 1816) with no issue. She was the daughter of Archduke Ferdinand of Austria-Este and Maria Beatrice d'Este, Princess of Modena.
 * 4) On 29 October 1816, to Karoline Charlotte Auguste of Bavaria (8 February 1792 – 9 February 1873) with no issue. She was daughter of Maximilian I Joseph of Bavaria and had been previously married to William I of Württemberg.

Children
From his first wife Elisabeth of Württemberg, one daughter, who died in infancy, and his second wife Maria Teresa of the Two Sicilies, eight daughters and four sons, of whom five died in infancy or childhood:

Titles
From 1806 he used the titles: "We, Francis the First, by the Grace of God Emperor of Austria; King of Jerusalem, Hungary, Bohemia, Dalmatia, Croatia, Slavonia, Galicia and Lodomeria; Archduke of Austria; Duke of Lorraine, Salzburg, Würzburg, Franconia, Styria, Carinthia and Carniola; Grand Duke of Cracow; Grand Prince of Transylvania; Margrave of Moravia; Duke of Sandomir, Masovia, Lublin, Upper and Lower Silesia, Auschwitz and Zator, Teschen and Friule; Prince of Berchtesgaden and Mergentheim; Princely Count of Habsburg, Gorizia and Gradisca and of the Tirol; and Margrave of Upper and Lower Lusatia and in Istria".

Orders and decorations
• Habsburg monarchy:

• * Knight of the Golden Fleece, 1768

• * Grand Cross of the Military Order of Maria Theresa, 1790

• * Founder and Grand Master of the Imperial Order of Leopold, 8 January 1808

• * Founder and Grand Master of the Order of the Iron Crown, 1815

• France:

• * French Empire: Grand Eagle of the Legion of Honour, 1811

• * Kingdom of France: Knight of the Holy Spirit, 1815

•  Kingdom of Bavaria: Knight of St. Hubert, 1813

•  Sweden: Grand Cross of the Sword, 1st Class, 20 February 1814

•  undefined: Stranger Knight of the Garter, 9 June 1814

• 🇩🇰 Denmark: Knight of the Elephant, 12 November 1814

•  Kingdom of Portugal: Grand Cross of the Sash of the Three Orders, 1818

•  Two Sicilies:

• * Knight of St. Januarius, 1821

• * Grand Cross of St. Ferdinand and Merit

•  Kingdom of Sardinia: Knight of the Annunciation, 3 January 1824

•  Russian Empire:

• * Knight of St. Andrew, 13 March 1826

• * Knight of St. Alexander Nevsky, 13 March 1826

•  Empire of Brazil:

• * Grand Cross of the Order of Pedro I, 1827

• * Grand Cross of the Southern Cross, 1830

•  Baden:

• * Grand Cross of the House Order of Fidelity, 1830

• * Grand Cross of the Zähringer Lion, 1830

•  Grand Duchy of Tuscany: Grand Cross of St. Joseph

title: Francis II, Holy Roman Emperor


text:
Frederick Abel

Sir Frederick Augustus Abel, 1st Baronet (17 July 1827  – 6 September 1902) was an English chemist who was recognised as the leading British authority on explosives. He is best known for the invention of cordite as a replacement for gunpowder in firearms.

Education
Born in London as son of Johann Leopold Abel, Abel studied chemistry at the Royal Polytechnic Institution and in 1845 became one of the original 26 students of A. W. von Hofmann at the Royal College of Chemistry (now a constituent of Imperial College London). In 1852 he was appointed lecturer in chemistry at the Royal Military Academy, Woolwich, succeeding Michael Faraday, who had held that post since 1829.

Early career
From 1854 until 1888 Abel served as ordnance chemist at the Chemical Establishment of the Royal Arsenal at Woolwich, establishing himself as the leading British authority on explosives. Three years later was appointed chemist to the War Department and chemical referee to the government. During his tenure of this office, which lasted until 1888, he carried out a large amount of work in connection with the chemistry of explosives.

Notable work
One of the most important of his investigations had to do with the manufacture of guncotton, and he developed a process, consisting essentially of reducing the nitrated cotton to fine pulp, which enabled it to be safely manufactured and at the same time yielded the product in a form that increased its usefulness. This work to an important extent prepared the way for the "smokeless powders" which came into general use towards the end of the 19th century; cordite, the type adopted by the British government in 1891, was invented jointly by him and Sir James Dewar. He and Dewar were unsuccessfully sued by Alfred Nobel over infringement of Nobel's patent for a similar explosive called ballistite, the case finally being resolved in the House of Lords in 1895. He also extensively researched the behaviour of black powder when ignited, with the Scottish physicist Sir Andrew Noble. At the request of the British government, he devised the Abel test, a means of determining the flash point of petroleum products. His first instrument, the open-test apparatus, was specified in an Act of Parliament in 1868 for officially specifying petroleum products. It was superseded in August 1879 by the much more reliable Abel close-test instrument. Under his leadership, first, guncotton was developed at Waltham Abbey Royal Gunpowder Mills, patented in 1865, then, the propellant cordite, patented in 1889. In electricity, Abel studied the construction of electrical fuses and other applications of electricity to warlike purposes.

Leadership and honours
He was elected a Fellow of the Royal Society in 1860 and received their Royal Medal in 1887. He was president of the Chemical Society (1875–77), of the Institution of Electrical Engineers (then the Society of Telegraph Engineers) (1877), of the Institute of Chemistry (1881–82) and of the Society of Chemical Industry (1882–83). He was also president of the Iron and Steel Institute in 1891 and was awarded the Bessemer Gold Medal in 1897 for his work on problems of steel manufacture. He was awarded the Telford Medal by the Institution of Civil Engineers in 1879.

He was made a Commander of the Order of the Bath (CB) in 1877. and knighted on 20 April 1883 He took an important part in the work of the Inventions Exhibition (London) in 1885, and in 1887 became organizing secretary and first director of the Imperial Institute, a position he held till his death in 1902. He was Rede Lecturer and received an honorary doctorate from Cambridge University in 1888. He was upgraded Knight Commander of the Order of the Bath (KCB) on 3 February 1891, created a baronet, of Cadogan Place in the Parish of Chelsea in the County of London, on 25 May 1893 and made a Knight Grand Cross of the Royal Victorian Order (GCVO) on 8 March 1901.

Abel died at his residence in Whitehall Court, London, on 6 September 1902, aged 75, and was buried in Nunhead Cemetery, London. The baronetcy became extinct on his death.

Family
Abel married twice; first to Sarah Blanch, daughter of James Blanch, of Bristol; secondly after his first wife's death to Giulietta de La Feuillade. He left no children.

Books

 * Handbook of Chemistry (with C. L. Bloxam)
 * The Modern History of Gunpowder (1866)
 * Gun-cotton (1866)
 * On Explosive Agents (1872)
 * Researches in Explosives (1875)
 * Electricity applied to Explosive Purposes (1898)
 * Electricity applied to Explosive Purposes (1898)

He also wrote several articles in the ninth edition of the Encyclopædia Britannica.

title: Frederick Abel


text:
Fugazi (disambiguation)

Fugazi is a family name and a slang word which refers to something that is fake or damaged beyond repair.

It may refer to:
 * Fugazi, a post-hardcore punk band from Washington, D.C.
 * Fugazi (EP), the debut EP by the band of the same name
 * Fugazi (album), a 1984 studio album by the British rock band Marillion, featuring a song also named "Fugazi"
 * Fugazi Bank Building, a 1908 historic building in San Francisco, California; commissioned by Giovanni "John" Fugazi (1838–1916)
 * Club Fugazi, a theater in the North Beach District of San Francisco, California, the perennial venue of Beach Blanket Babylon

title: Fugazi (disambiguation)