Name and titles.

Nurhaci is written as in Manchu language. Some suggests that the meaning of the name in the Manchu language is "the skin of a wild boar". Regarded as the founding father of the Qing dynasty, he is given the customary temple name of "Taizu", which is traditionally assigned to founders of dynasties. His name is also alternatively spelled "Nurgaci", "Nurhachi", or "Nu-er-ha-chi" (the last of these simply the transcription of the Chinese characters used to write his name).  Nurhaci was the last chieftain of the Jianzhou Jurchens and First Khan of the Later Jin dynasty. His title in Manchu as Khan was "Geren Gurun-be Ujire Genggiyen Han" ("Brilliant Khan Who Benefits All Nations"). His regnal name was Tianming (; Manchu:"Abkai Fulingga"), in Mongolian Тэнгэрийн сүлдэт Tengri-yin Süldetü. It means "The Emperor of Heaven's Mandate." He was given a posthumous name in 1736 (see infobox), the shortened form of which was "Emperor Gao" (Wade–Giles: Emperor Kao;, Manchu:"Dergi Hūwangdi")

Early life.

Nurhaci was born on 8 April 1559. Being a member of the Gioro clan of the Suksuhu River tribe, Nurhaci also claimed descent from Mentemu, a Jurchen headman who lived some two centuries earlier. The young man grew up as a soldier in the household of the Ming dynasty general Li Chengliang in Fushun, where he learned a Chinese dialect, possibly Quonha, the official dialect of the courts. Nurhaci read the Chinese novels Romance of the Three Kingdoms and Water Margin learning all he knew about Chinese military and political strategies from them. He named his clan Aisin Gioro around 1612, when he formally ascended the throne as the Khan of the Later Jin dynasty.  In 1582, Nurhaci's father Taksi and grandfather Giocangga were killed in an attack on Gure (now a village in Xinbin Manchu Autonomous County) by a rival Jurchen chieftain, Nikan Wailan ("Nikan Wailan" means "secretary of Han Chinese" in the Jurchen language, thus his existence is suspected by some historians.) while being led by Li Chengliang. The following year, Nurhaci began to unify the Jurchen bands around his area.  In 1584, when Nurhaci was 25, he attacked Nikan Wailan at Turun (today a village in Xinbin too) to avenge the deaths of his father and grandfather, who are said to have left him nothing but thirteen suits of armor. Nikan Wailan fled away to Erhun, which Nurhaci attacked again in 1587. Nikan Wailan this time fled to Li Chengliang's territory. Later, as a way to build relationship, Li gave Nikan Wailan to Nurhaci, who beheaded Nikan Wailan immediately. With Li's support, Nurhaci gradually grew his strength in the following years.

Unifying the Jurchen tribes.

In 1593, the Yehe called upon a coalition of nine tribes: the Hada, Ula, Hoifa, Khorchin Mongols, Sibe, Guwalca, Jušeri, Neyen, and the Yehe themselves to attack the Jianzhou Jurchens. The coalition was defeated at the Battle of Gure and Nurhaci emerged victorious.  From 1599 to 1618, Nurhaci set out on a campaign against the four Hulun tribes. He began by attacking the Hada in 1599 and conquering them in 1603. Then in 1607, Hoifa was also conquered with the death of its beile Baindari, followed by an expedition against Ula and its "beile" Bujantai in 1613, and finally the Yehe and its beile Gintaisi at the Battle of Sarhu in 1619.  In 1599, Nurhaci gave two of his translators, Erdeni Baksi ('Jewel Teacher' in Mongolian) and Dahai Jargūci, the task of creating a Manchu alphabet by adapting the Mongolian script.  In 1606, he was granted the title of Kundulun Khan by the Mongols. In 1616, Nurhaci declared himself Khan and founded the Jin dynasty ("aisin gurun"), often called the Later Jin in reference to the legacy of the "earlier" Jurchen Jin dynasty of the 12th century. He constructed a palace at Mukden (present-day Shenyang, Liaoning). The "Later Jin" was renamed to "Qing" by his son Hong Taiji after his death in 1626, however Nurhaci is usually referred to as the founder of the Qing dynasty.  In order to help with the newly organized administration, five of his trusted companions were appointed as his chief councilors, Anfiyanggū, Eidu, Hūrhan, Fiongdon, and Hohori.  Only after he became Khan did he finally unify the Ula (clan of his consort Lady Abahai, mentioned below) and the Yehe, the clan of his consort Monggo Jerjer.  Nurhaci chose to variously emphasize either differences or similarities in lifestyles with other peoples like the Mongols for political reasons. Nurhaci said to the Mongols that "The languages of the Chinese and Koreans are different, but their clothing and way of life is the same. It is the same with us Manchus (Jurchen) and Mongols. Our languages are different, but our clothing and way of life is the same." Later Nurhaci indicated that the bond with the Mongols was not based in any real shared culture, rather it was for pragmatic reasons of "mutual opportunism", when he said to the Mongols: "You Mongols raise livestock, eat meat and wear pelts. My people till the fields and live on grain. We two are not one country and we have different languages."  When the Jurchens were reorganized by Nurhaci into the Eight Banners, many Manchu clans were artificially created as a group of unrelated people founded a new Manchu clan (mukun) using a geographic origin name such as a toponym for their hala (clan name). The irregularities over Jurchen and Manchu clan origin led to the Qing trying to document and systematize the creation of histories for Manchu clans, including manufacturing an entire legend around the origin of the Aisin Gioro clan by taking mythology from the northeast.

Challenging Ming China.

In 1618, Nurhaci commissioned a document entitled the Seven Grievances in which he enumerated seven problems with Ming rule and began to rebel against the domination of the Ming dynasty. A majority of the grievances dealt with conflicts against Yehe, and Ming favouritism of Yehe.  Nurhaci led many successful engagements against the Ming Chinese, the Koreans, the Mongols, and other Jurchen clans, greatly enlarging the territory under his control.  The first capitals of the state established by Nurhaci were Fe Ala and Hetu Ala. Han Chinese participated in the construction of Hetu Ala, the capital of Nurhaci's state.  Defectors from the Ming side played a massive role in the Qing conquest of the Ming. Ming generals who defected to the Manchus were often married to women from the Aisin Gioro clan while lower-ranked defectors were given non-imperial Manchu women as wives. Nurhaci arranged for a marriage between one of his granddaughters and the Ming general Li Yongfang (李永芳) after Li surrendered Fushun in Liaoning to the Manchus in 1618 as the result of the Battle of Fushun. His son Abatai's daughter was married to Li Yongfang. The offspring of Li received the "Third Class Viscount" () title. Li Yongfang was the great great great grandfather of Li Shiyao 李侍堯.  The Han prisoner of war Gong Zhenglu (Onoi) was appointed to instruct Nurhaci's sons and received gifts of slaves, wives, and a domicile from Nurhaci after Nurhaci rejected offers of payment to release him back to his relatives.  Nurhaci had treated Han in Liaodong differently according to how much grain they had, those with less than 5 to 7 sin were treated like chattel while those with more than that amount were rewarded with property. Due to a revolt by Han in Liaodong in 1623, Nurhachi, who previously gave concessions to conquered Han subjects in Liaodong, turned against them and ordered that they no longer be trusted and enacted discriminatory policies and killings against them, while ordering that Han who assimilated to the Jurchen (in Jilin) before 1619 be treated equally as Jurchens were and not like the conquered Han in Liaodong.  By May 1621, Nurhaci had conquered the cities of Liaoyang and Shenyang. In April 1625, he designated Shenyang the new capital city, which would hold that status until the Qing conquest of the Ming in 1644. Finally in 1626, Nurhaci suffered the first serious military defeat of his life at the hands of the Ming general Yuan Chonghuan. Nurhaci was wounded by the Portuguese-made cannons in Yuan's army at the Battle of Ningyuan. Unable to recover either physically or mentally, he died two days later in Aiji Fort (靉雞堡; in present-day Da'aijinbao Village, Dijia Township, Yuhong District, Shenyang) on 30 September at the age of 67. His tomb, Fu Mausoleum (), is located east of Shenyang.  The first Manchu translations of Chinese works were the "Six Secret Teachings" (), "Sushu" 素書, and "Three Strategies of Huang Shigong" (), all Chinese military texts dedicated to the arts of war due to the Manchu interests in the topic, like Sun-Tzu's work The Art of War. The military related texts which were translated into Manchu from Chinese were translated by Dahai.  Manchu translations of Chinese texts included the Ming penal code and military texts were performed by Dahai. These translations were requested of Dahai by Nurhaci. The military text "Wuzi" was translated into Manchu along with "The Art of War".  Chinese history, Chinese law, and Chinese military theory classical texts were translated into Manchu during the rule of Hong Taiji in Mukden (now Shenyang), with the Manchus placing significance upon military and governance related Chinese texts. A Manchu translation was made of the military-themed novel "Romance of the Three Kingdoms". Chinese literature, military theory and legal texts were translated into Manchu by Dahai and Erdeni. The translations were ordered in 1629.  The translation of the military texts "Sushu" and "Three Strategies of Huang Shigong", and the Da Ming Huidian () done by Dahai was ordered by Nurhaci. While it was mainly administrative and ethical guidance which made up most of the "Three Strategies of Huang Shigong" and the "Sushu", military science was indeed found in the "Six Secret Teachings" and Chinese military manuals were eagerly translated by the Manchus. They were also attracted to the military content in "Romance of the Three Kingdoms", which is why it was translated. "The Art of War" was translated into Manchu as Abkai: qoohai baita be gisurengge, Möllendorff: coohai baita be gisurengge, Discourse on the art of War. Another later Manchu translation was made by Aisin Gioro Qiying.

Legacy.

Among the most lasting contributions Nurhaci left his descendants was the establishment of the Eight Banners, which would eventually form the backbone of the military that dominated the Qing Empire. The status of Banners did not change much over the course of Nurhaci's lifetime, nor in subsequent reigns, remaining mostly under the control of the royal family. The two elite Yellow Banners were consistently under Nurhaci's control. The two Blue Banners were controlled by Nurhaci's brother Šurhaci until he died, at which point the Blue Banners were given to Šurhaci's two sons, Chiurhala and Amin. Nurhaci's eldest son, Cuyen, controlled the White Banner for most of his father's reign until he rebelled. Then the Bordered White Banner was given to Nurhaci's grandson and the Plain White was given to his eighth son and heir, Hong Taiji. However, by the end of Nurhaci's reign, Hong Taiji controlled both White Banners. Finally, the Red Banner was run by Nurhaci's second son Daišan. Later in Nurhaci's reign, the Bordered Red Banner was handed down to his son. Daišan and his son would continue holding the two Red Banners well into the end of Hong Taiji's reign. The details of Hong Taiji's succession as the Khan of the Later Jin dynasty are unclear. When he died in late 1626, Nurhaci did not designate an heir; instead he encouraged his sons to rule collegially. Three of his sons and a nephew were the "four senior beiles": Daišan (43 years old), Amin (son of Nurhaci's brother Šurhaci; 40 or 41), Manggūltai (38 or 39), and Hong Taiji himself (33). On the day after Nurhaci's death, they coerced his primary consort Lady Abahai (1590–1626) – who had borne him three sons: Ajige, Dorgon, and Dodo – to commit suicide to accompany him in death. This gesture has made some historians suspect that Nurhaci had in fact named the fifteen-year-old Dorgon as a successor, with Daišan as regent. By forcing Dorgon's mother to kill herself, the princes removed a strong base of support for Dorgon. The reason such intrigue was necessary is that Nurhaci had left the two elite Yellow Banners to Dorgon and Dodo, who were the sons of Lady Abahai. Hong Taiji exchanged control of his two White Banners for that of the two Yellow Banners, shifting their influence and power from his young brothers onto himself.  According to Hong Taiji's later recollections, Amin and the other "beile" were willing to accept Hong Taiji as Khan, but Amin then would have wanted to leave with his Bordered Blue Banner, threatening to dissolve Nurhaci's unification of the Jurchens. Eventually the older Daišan worked out a compromise that allowed Hong Taiji as the Khan, but almost equal to the other three senior beiles. Hong Taiji would eventually find ways to become the undisputed leader.  The change of the name from Jurchen to Manchu by Hong Taiji was made to hide the fact that the ancestors of the Manchus, the Jianzhou Jurchens, were ruled by the Chinese. The Qing dynasty carefully hid the two original editions of the books of ""Qing Taizu Wu Huangdi Shilu"" and the ""Manzhou Shilu Tu"" (Taizu Shihlu Tu) in the Qing palace, forbidden from public view because they showed that the Manchu Aisin Gioro family had been ruled by the Ming dynasty. In the Ming period, the Koreans of Joseon referred to the Jurchen-inhabited lands north of the Korean peninsula, above the rivers Yalu and Tumen, as part of Ming China, which they called the "superior country" (sangguk).

Primary sources.

Information concerning Nurhaci can be found in later, propagandistic works such as the "Manchu Veritable Records" (; Manchu:, Mölendroff: manju-i yargiyan kooli). Good contemporary sources are also available. For instance, much material concerning Nurhaci's rise is preserved within Korean sources such as the "Veritable Records of the Joseon Dynasty" (), especially the "Seonjo Sillok" and the "Gwanghaegun Ilgi". Indeed, the record of Sin Chung-il's trip to Jianzhou is preserved in the "Seonjo Sillok".  The "Jiu Manzhou Dang" from Nurhaci's reign also survives. A revised transcription of these records (with the dots and circles added to the script) was commissioned by the Qianlong Emperor. This has been translated into Japanese under the title "Manbun roto", and Chinese, under the title "Manwen Laodang" (). A project is currently under way at Harvard University to translate them into English, as "The Old Manchu Chronicles".

Physical appearance.

According to the account of Korean ambassadors, Nurhaci was a physically strong man with a long and stern-looking face and that his nose was straight and big, and just like most of the other Manchu men, he shaved most of his facial hair and kept only his moustache.

Science.

The genus "Nurhachius", a pterodactyloid pterosaur, is named after Nurhaci.

The electric dipole moment is a measure of the separation of positive and negative electrical charges within a system, that is, a measure of the system's overall polarity. The SI units for electric dipole moment are coulomb-meter (C⋅m); however, a commonly used unit in atomic physics and chemistry is the debye (D).

在物理学里,电偶极矩衡量正电荷分布与负电荷分布的分离状况,即电荷系统的整体极性。


Classification.

A "physical dipole" consists of two equal and opposite point charges: in the literal sense, two poles. Its field at large distances (i.e., distances large in comparison to the separation of the poles) depends almost entirely on the dipole moment as defined above. A "point (electric) dipole" is the limit obtained by letting the separation tend to 0 while keeping the dipole moment fixed. The field of a point dipole has a particularly simple form, and the order-1 term in the multipole expansion is precisely the point dipole field.  Although there are no known magnetic monopoles in nature, there are magnetic dipoles in the form of the quantum-mechanical spin associated with particles such as electrons (although the accurate description of such effects falls outside of classical electromagnetism). A theoretical magnetic "point dipole" has a magnetic field of exactly the same form as the electric field of an electric point dipole. A very small current-carrying loop is approximately a magnetic point dipole; the magnetic dipole moment of such a loop is the product of the current flowing in the loop and the (vector) area of the loop.  Any configuration of charges or currents has a 'dipole moment', which describes the dipole whose field is the best approximation, at large distances, to that of the given configuration. This is simply one term in the multipole expansion when the total charge ("monopole moment") is 0—as it "always" is for the magnetic case, since there are no magnetic monopoles. The dipole term is the dominant one at large distances: Its field falls off in proportion to, as compared to for the next (quadrupole) term and higher powers of for higher terms, or for the monopole term.

Molecular dipoles.

Many molecules have such dipole moments due to non-uniform distributions of positive and negative charges on the various atoms. Such is the case with polar compounds like hydrogen fluoride (HF), where electron density is shared unequally between atoms. Therefore, a molecule's dipole is an electric dipole with an inherent electric field that should not be confused with a magnetic dipole which generates a magnetic field.  The physical chemist Peter J. W. Debye was the first scientist to study molecular dipoles extensively, and, as a consequence, dipole moments are measured in units named "debye" in his honor.  For molecules there are three types of dipoles:  More generally, an induced dipole of "any" polarizable charge distribution "ρ" (remember that a molecule has a charge distribution) is caused by an electric field external to "ρ". This field may, for instance, originate from an ion or polar molecule in the vicinity of "ρ" or may be macroscopic (e.g., a molecule between the plates of a charged capacitor). The size of the induced dipole moment is equal to the product of the strength of the external field and the dipole polarizability of "ρ".  Dipole moment values can be obtained from measurement of the dielectric constant. Some typical gas phase values in debye units are:  Potassium bromide (KBr) has one of the highest dipole moments because it is an ionic compound that exists as a molecule in the gas phase. The overall dipole moment of a molecule may be approximated as a vector sum of bond dipole moments. As a vector sum it depends on the relative orientation of the bonds, so that from the dipole moment information can be deduced about the molecular geometry.  For example, the zero dipole of CO implies that the two C=O bond dipole moments cancel so that the molecule must be linear. For HO the O−H bond moments do not cancel because the molecule is bent. For ozone (O) which is also a bent molecule, the bond dipole moments are not zero even though the O−O bonds are between similar atoms. This agrees with the Lewis structures for the resonance forms of ozone which show a positive charge on the central oxygen atom. An example in organic chemistry of the role of geometry in determining dipole moment is the "cis" and "trans" isomers of 1,2-dichloroethene. In the "cis" isomer the two polar C−Cl bonds are on the same side of the C=C double bond and the molecular dipole moment is 1.90 D. In the "trans" isomer, the dipole moment is zero because the two C−Cl bonds are on opposite sides of the C=C and cancel (and the two bond moments for the much less polar C−H bonds also cancel).  Another example of the role of molecular geometry is boron trifluoride, which has three polar bonds with a difference in electronegativity greater than the traditionally cited threshold of 1.7 for ionic bonding. However, due to the equilateral triangular distribution of the fluoride ions about the boron cation center, the molecule as a whole does not exhibit any identifiable pole: one cannot construct a plane that divides the molecule into a net negative part and a net positive part.

Quantum mechanical dipole operator.

Consider a collection of "N" particles with charges "q" and position vectors r. For instance, this collection may be a molecule consisting of electrons, all with charge −"e", and nuclei with charge "eZ", where "Z" is the atomic number of the "i" th nucleus. The dipole observable (physical quantity) has the quantum mechanical dipole operator:  Notice that this definition is valid only for neutral atoms or molecules, i.e. total charge equal to zero. In the ionized case, we have where formula_3 is the center of mass of the molecule/group of particles.

Atomic dipoles.

A non-degenerate ("S"-state) atom can have only a zero permanent dipole. This fact follows quantum mechanically from the inversion symmetry of atoms. All 3 components of the dipole operator are antisymmetric under inversion with respect to the nucleus,  where formula_5 is the dipole operator and formula_6 is the inversion operator.  The permanent dipole moment of an atom in a non-degenerate state (see degenerate energy level) is given as the expectation (average) value of the dipole operator,  where formula_8 is an "S"-state, non-degenerate, wavefunction, which is symmetric or antisymmetric under inversion: formula_9. Since the product of the wavefunction (in the ket) and its complex conjugate (in the bra) is always symmetric under inversion and its inverse,  it follows that the expectation value changes sign under inversion. We used here the fact that formula_11, being a symmetry operator, is unitary: formula_12 and by definition the Hermitian adjoint formula_13 may be moved from bra to ket and then becomes formula_14. Since the only quantity that is equal to minus itself is the zero, the expectation value vanishes,  In the case of open-shell atoms with degenerate energy levels, one could define a dipole moment by the aid of the first-order Stark effect. This gives a non-vanishing dipole (by definition proportional to a non-vanishing first-order Stark shift) only if some of the wavefunctions belonging to the degenerate energies have opposite parity; i.e., have different behavior under inversion. This is a rare occurrence, but happens for the excited H-atom, where 2s and 2p states are "accidentally" degenerate (see article Laplace–Runge–Lenz vector for the origin of this degeneracy) and have opposite parity (2s is even and 2p is odd).

Field of a static magnetic dipole.

Magnitude.

The far-field strength, "B", of a dipole magnetic field is given by  where  Conversion to cylindrical coordinates is achieved using and  where "ρ" is the perpendicular distance from the "z"-axis. Then,

Vector form.

The field itself is a vector quantity:  where  This is "exactly" the field of a point dipole, "exactly" the dipole term in the multipole expansion of an arbitrary field, and "approximately" the field of any dipole-like configuration at large distances.

Magnetic vector potential.

The vector potential A of a magnetic dipole is  with the same definitions as above.

Field from an electric dipole.

The electrostatic potential at position r due to an electric dipole at the origin is given by:  where p is the (vector) dipole moment, and "є" is the permittivity of free space.  This term appears as the second term in the multipole expansion of an arbitrary electrostatic potential Φ(r). If the source of Φ(r) is a dipole, as it is assumed here, this term is the only non-vanishing term in the multipole expansion of Φ(r). The electric field from a dipole can be found from the gradient of this potential:  This is formally identical to the expression for the magnetic field of a point magnetic dipole with only a few names changed. In a real dipole, however, where the charges are physically separate, the "internal" field lines are different, since the magnetic field lines are continuous, while those of the electric field diverge or converge from the point charges. For further discussions about the internal field of dipoles, see or Magnetic moment#Internal magnetic field of a dipole.

Torque on a dipole.

Since the direction of an electric field is defined as the direction of the force on a positive charge, electric field lines point away from a positive charge and toward a negative charge.  When placed in an homogeneous electric or magnetic field, equal but opposite forces arise on each side of the dipole creating a torque }:  for an electric dipole moment p (in coulomb-meters), or  for a magnetic dipole moment m (in ampere-square meters).  The resulting torque will tend to align the dipole with the applied field, which in the case of an electric dipole, yields a potential energy of  The energy of a magnetic dipole is similarly

Dipole radiation.

In addition to dipoles in electrostatics, it is also common to consider an electric or magnetic dipole that is oscillating in time. It is an extension, or a more physical next-step, to spherical wave radiation.  In particular, consider a harmonically oscillating electric dipole, with angular frequency "ω" and a dipole moment "p" along the ẑ direction of the form  In vacuum, the exact field produced by this oscillating dipole can be derived using the retarded potential formulation as:  For ≫ 1, the far-field takes the simpler form of a radiating "spherical" wave, but with angular dependence embedded in the cross-product:  The time-averaged Poynting vector  is not distributed isotropically, but concentrated around the directions lying perpendicular to the dipole moment, as a result of the non-spherical electric and magnetic waves. In fact, the spherical harmonic function (sin "θ") responsible for such toroidal angular distribution is precisely the "l" = 1 "p" wave.  The total time-average power radiated by the field can then be derived from the Poynting vector as  Notice that the dependence of the power on the fourth power of the frequency of the radiation is in accordance with the Rayleigh scattering, and the underlying effects why the sky consists of mainly blue colour.  A circular polarized dipole is described as a superposition of two linear dipoles.

In electromagnetism, there are two kinds of dipoles:

在电磁学里,有两种偶极子(dipole):


Administrative divisions.

Namp'o is divided into 5 "kuyŏk" and 2 "kun", which are in turn subdivided into "tong" and "ri":

Transportation.

Road.

The Youth Hero Motorway connects Namp'o to P'yŏngyang.

Air.

Onch'ŏn Airport in Onch'ŏn-gun serves Namp'o Special City; Air Koryo operates charter flights from here.

Rail.

The greater Namp'o area is densely served by the Korean State Railway, with 18 stations on the P'yŏngnam Line, the entirety of the Ryonggang Sŏhaekammun and Taean lines, and one station on the Ŭllyul Line being located inside the boundaries of Namp'o-t'ŭkpyŏlsi.

Sea.

The West Sea Barrage of the port of Namp'o, built by erecting an 8-km long sea wall, has three lock chambers which allow the passage of ships up to 50,000 tons, and 36 sluices. Namp'o Harbour is often used as the primary port of call for receiving foreign food aid assistance into North Korea. The port of Namp'o has modern harbour facilities that can accommodate ships of 20,000 tonnes but is frozen during the winter. Namp'o serves as Pyongyang's port on the Yellow Sea.  In 2008, the harbour received several batches of grain delivery; the first batch delivered in June was sent by the United States and weighed 38,000 tons. A South Korean-based relief organisation, Join Together Society, donated one batch of flour in October of the same year weighing approximately 500 tons.

Education.

Institutes of higher learning in Namp'o include

Nampo (North Korean official spelling: "Nampho"; ), also spelled Nampo, is a city and seaport in South Pyongan Province, North Korea, which lies on the northern shore of the Taedong River, 15 km east of the river's mouth. Formerly known as Chinnampo, it was a provincial-level "Directly Governed City" ("Chikhalsi") from 1980 to 2004, and was designated a "Special City" ("T'ŭkgŭpsi"; "tŭkpyŏlsi"; 특별시; 特別市) in 2010, and made a part of South P'yŏngan. Namp'o is approximately 50 km southwest of P'yŏngyang, at the mouth of the Taedong River.

南浦特别市()是朝鲜的一个特别市,是平壤重要的贸易港口、工业都市。人口366,815(2008年人口普查)。


History.

Evaporative cooling.

Since prehistoric times, snow and ice were used for cooling. The business of harvesting ice during winter and storing for use in summer became popular towards the late 17th century. This practice was replaced by mechanical ice-making machines.  The basic concept behind air conditioning is said to have been applied in ancient Egypt, where reeds were hung in windows and were moistened with trickling water. The evaporation of water cooled the air blowing through the window. This process also made the air more humid, which can be beneficial in a dry desert climate. Other techniques in

Development of mechanical cooling.

In 1758, Benjamin Franklin and John Hadley, a chemistry professor at Cambridge University, conducted an experiment to explore the principle of evaporation as a means to rapidly cool an object. Franklin and Hadley confirmed that evaporation of highly volatile liquids (such as alcohol and ether) could be used to drive down the temperature of an object past the freezing point of water. They conducted their experiment with the bulb of a mercury thermometer as their object and with a bellows used to speed up the evaporation.

Electrical air conditioning.

The creation of the modern electrical air conditioning unit and industry is credited to the American inventor Willis H. Carrier. After graduating from Cornell University, Carrier found a job at the Buffalo Forge Company. There, he began experimenting with air conditioning as a way to solve an application problem for the Sackett-Wilhelms Lithographing and Publishing Company in Brooklyn, New York. The first air conditioner, designed and built in Buffalo, New York by Carrier, began working on 17 July 1902.  Designed to improve manufacturing process control in a printing plant, Carrier's invention controlled not only temperature but also humidity. Carrier used his knowledge of the heating of objects with steam and reversed the process. Instead of sending air through hot coils, he sent it through cold coils (filled with cold water). The air was cooled, and thereby the amount of moisture in the air could be controlled, which in turn made the humidity in the room controllable. The controlled temperature and humidity helped maintain consistent paper dimensions and ink alignment. Later, Carrier's technology was applied to increase productivity in the workplace, and The Carrier Air Conditioning Company of

Refrigerant development.

The first air conditioners and refrigerators employed toxic or flammable gases, such as ammonia, methyl chloride, or propane, that could result in fatal accidents when they leaked. Thomas Midgley, Jr. created the first non-flammable, non-toxic chlorofluorocarbon gas, "Freon" (R-12), in 1928. The name is a trademark name owned by DuPont for any chlorofluorocarbon (CFC), hydrochlorofluorocarbon (HCFC), or hydrofluorocarbon (HFC) refrigerant. The refrigerant names include a number indicating the molecular composition (e.g., R-11, R-12, R-22, R-134A). The blend most used in direct-expansion home and building comfort cooling is an

Operating principles.

Refrigeration cycle.

Cooling in traditional AC systems is accomplished using the vapor-compression cycle, which uses the forced circulation and phase change of a refrigerant between gas and liquid to transfer heat.  The vapor-compression cycle can occur within a unitary, or packaged piece of equipment; or within a chiller that is connected to terminal cooling equipment (such as a variable refrigerant flow terminal or fan coil unit) on its evaporator side and heat rejection equipment on its condenser side.

Heat pump.

Main article: Heat pump  Some air conditioning systems have the option to reverse the refrigeration cycle and act as heat pumps, therefore producing heating instead of cooling in the indoor environment. They are also commonly referred to as "reverse cycle air conditioner". The heat pump is significantly more energy efficient than electric resistance heating, because it moves energy from air or groundwater to the heated space, as well as the heat from purchased electrical energy. When the heat pump is in heating mode, the indoor evaporator coil switches roles and becomes the condenser coil, producing heat. The outdoor condenser unit also switches roles to serve as the evaporator, and discharges cold air (colder than the ambient outdoor air).  Air-source heat pumps are more popular in milder winter climates where the temperature is

Evaporative cooling.

In very dry climates, evaporative coolers, sometimes referred to as swamp coolers or desert coolers, are popular for improving coolness during hot weather. An evaporation cooler is a device that draws outside air through a wet pad, such as a large sponge soaked with water. The sensible heat of the incoming air, as measured by a dry bulb thermometer, is reduced. The temperature of the incoming air is reduced, but it is also more humid, so the total heat (sensible heat plus latent heat) is unchanged. Some of the sensible heat of the entering air is

Free cooling.

Air conditioning can also be provided by a process called free cooling which uses pumps to circulate a coolant such as air, water, or a water-glycol mixture from a cold source, which in turn acts as a heat sink for the energy that is removed from the cooled space. Common storage media are cool outside air, deep aquifers, or a natural underground rock mass accessed

Humidity control.

Since humans perspire to provide natural cooling by the evaporation of perspiration from the skin, reducing relative humidity can promote occupant comfort. An air conditioner designed for an occupied space typically will create a 30% to 60% relative humidity in the occupied space to balance comfort, microbial growth, and other indoor air quality factors.

Dehumidification and cooling.

Air conditioning equipment will reduce the absolute humidity of the air processed by the system if the surface of the

Dehumidification program.

Most modern air-conditioning systems feature a dehumidification cycle during which the compressor runs while the fan is slowed as much as possible to reduce the evaporator temperature and therefore condense more water. When the temperature falls below a threshold, both the fan and compressor are shut off to mitigate further temperature drops; this prevents moisture on

Dehumidifier.

A specialized air conditioner that is used only for dehumidifying is called a dehumidifier. It also uses a refrigeration cycle, but differs from a standard air conditioner in that both the evaporator and the condenser are placed in the same air path. A standard air conditioner transfers heat energy out of the room because its condenser coil releases heat outside. However, since all components of the dehumidifier are in the "same" room, no heat energy is removed. Instead, the electric power consumed by the dehumidifier remains in the room as heat, so the room is actually "heated", just as by an electric heater that draws the same amount of power.  In addition, if water

Energy transfer.

In a thermodynamically closed system, any power dissipated into the system that is being maintained at a set temperature (which is a standard mode of operation for modern air conditioners) requires that the rate of energy removal by the air conditioner increase. This increase has the effect that, for each unit of energy input into the system (say to power a light bulb in the closed system), the air conditioner removes that energy. To do so, the air conditioner must increase its power consumption by the inverse of its "efficiency" (coefficient of performance) times the amount of power dissipated into the system. As an example, assume that inside the closed system a 100 W heating element is activated, and the air conditioner has a coefficient of performance of 200%. The air conditioner's power consumption will increase by 50 W to compensate for this, thus making the 100 W heating element cost a total of 150 W of power.  It is typical for air conditioners to operate at "efficiencies" of significantly greater than 100%. However, it may be noted that the input electrical energy is of higher thermodynamic quality (lower entropy) than the output thermal energy (heat energy).  Air conditioner equipment power in the U.S. is often described in terms of "tons of refrigeration", with each approximately equal to the cooling power of one short ton (2000 pounds or 907 kilograms) of ice melting in a 24-hour period. The value is defined as 12,000 BTU per hour, or 3517 watts. Residential central air systems are usually from 1 to 5 tons (3.5 to 18 kW) in capacity.

Seasonal energy efficiency ratio.

For residential homes, some countries set minimum requirements for energy efficiency. In the United States, the efficiency of air conditioners is often (but not always) rated by the seasonal energy efficiency ratio (SEER). The higher the SEER rating, the more energy efficient is the air conditioner. The SEER rating is the BTU of cooling output during its normal annual usage divided by the total electric energy input in watt hours (W·h) during the same period.  this can also be rewritten as:  For example, a 5000 BTU/h air-conditioning unit, with a SEER of 10, would consume 5000/10 = 500 Watts of power on average.  The electrical energy consumed per year can be calculated as the average power multiplied by the annual operating time:  Assuming 1000 hours of operation during a typical cooling season (i.e., 8 hours per day for 125 days

Installation types.

Window unit and packaged terminal.

Window unit air conditioners are installed in an open window. The interior air is cooled as a fan blows it over the evaporator. On the exterior the heat drawn from the interior is dissipated into the environment as a second fan blows outside air over the condenser. A large house or building may have several such units, allowing each room to be cooled separately.  In 1971, General Electric introduced a popular portable in-window air conditioner designed for convenience and portability.  Packaged terminal air conditioner (PTAC) systems are also known as wall-split air conditioning systems. They are

Split systems.

Split-system air conditioners come in two forms: mini-split and central systems. In both types, the inside-environment (evaporative) heat exchanger is separated by some distance from the outside-environment (condensing unit) heat exchanger.

Split central (ducted) system.

Common in U.S. homes and businesses, both in the U.S. and abroad. In these, an air handler that may contain a fan coil unit, a mechanism to heat the air and filter is placed inside a house or building and is connected to a condensing unit, which is outdoors. The air handler is controlled by a thermostat placed some distance away from the air handler. A user sets a desired temperature on the

Mini-split (ductless) system.

A mini-split system typically supplies air conditioned and heated air to a single or a few rooms of a building. The name mini-split is often used to refer to those mini-split systems that only supply air to a single room. Multi-zone systems are a common application of ductless systems and allow up to 8 rooms (zones) to be conditioned from a single outdoor unit. Multi-zone systems typically offer a variety of indoor unit styles including wall-mounted, ceiling-mounted, ceiling recessed, and horizontal ducted. Mini-split systems typically produce per hour of cooling to a single room or indoor unit. The first mini-split systems were sold in 1954-1968 by Mitsubishi Electric and Toshiba, in Japan. Its invention was motivated by the small size of modern Japanese homes, and the large size of traditional ducted central split systems. Multi-zone (multi-split) systems provide extended cooling and heating capacity up to 60,000 Btu's to multiple rooms or indoor units simultaneously.

Multi-split system.

A multi-split system is a conventional split system, which is divided into two parts (evaporator and condenser) and allows cooling or heating of several rooms with one external unit. In the outdoor unit of this air conditioner there is a more powerful compressor, ports for connecting several traces and automation with locking valves for regulating the volume of refrigerant supplied to the indoor units located in the room.  A large Multi Split System is called a Variable refrigerant flow system and can be used instead of a central air conditioner

Air-only central air conditioning.

Central ducted A/C provides temperature control and ventilation to an area by conditioning air within an air handler

Central plant cooling.

Central cooling plants are used to condition large commercial, industrial, or campus loads. At larger scales, the ductwork required to move conditioned air to and from the plant would be impractically large, so an

Portable units.

A portable air conditioner can be easily transported inside a home or office. They are currently available with capacities of about and with or without electric-resistance heaters. Portable air conditioners are either evaporative or refrigerative.  The compressor-based refrigerant systems are air-cooled, meaning they use air to exchange heat, in the same way as a car radiator or typical household air conditioner does. Such a system dehumidifies the air as it cools it. It collects water condensed from the cooled air and produces hot air which must be vented outside the cooled area; doing so transfers heat from the air in the cooled area to the outside air.

Portable split system.

A portable system has an indoor unit on wheels connected to an outdoor unit via flexible pipes, similar to a

Portable hose system.

Hose systems, which can be "monoblock" or "air-to-air", are vented to the outside via air ducts. The "monoblock" type collects the water in a bucket or tray and stops when full. The "air-to-air" type re-evaporates the water and discharges it through the ducted hose and can run continuously.  A single-hose unit uses air from within the room to cool

Portable evaporative system.

Evaporative coolers, sometimes called "swamp coolers", do not have a compressor or condenser. Liquid water is evaporated on the cooling fins, releasing the vapor into the cooled area. Evaporating water absorbs a significant amount of heat, the latent heat of vaporisation, cooling the air. Humans and animals use the same mechanism to cool themselves by sweating.  Evaporative coolers have the advantage of needing no hoses to vent heat outside the cooled area, making them truly portable. They are also very cheap to install and use less energy than refrigerative air conditioners.

Uses.

Air-conditioning engineers broadly divide air conditioning applications into "comfort" and "process" applications.

Comfort applications.

Comfort applications aim to provide a building indoor environment that remains relatively constant despite changes in external weather conditions or in internal heat loads.  Air conditioning makes deep plan buildings feasible, for otherwise they would have to be built narrower or with light wells so that inner spaces received sufficient outdoor air via natural ventilation. Air conditioning also allows buildings to be taller, since wind speed increases significantly with altitude making natural ventilation impractical for very tall buildings. Comfort applications are quite different for various building types and may be categorized as:  Women have, on average, a significantly lower resting metabolic rate than men. Using inaccurate metabolic rate guidelines for air conditioning sizing can result in oversized and less efficient equipment, and setting system operating setpoints too cold can result in reduced worker productivity. Dubai makes extensive use of air conditioning.  In addition to buildings, air conditioning can be used for many types of transportation, including automobiles, buses and other land vehicles, trains, ships, aircraft, and spacecraft. High temperatures in metro system stations may be caused by train air conditioning.

Domestic usage.

Air conditioning is common in the US, with 90% of new single-family homes constructed in 2019 including air conditioning, ranging from 99% in the South to 62% in the West. This has been the case since the 1960s. In 2015, 90% of U.S. households had air conditioning. The U.S consumes more energy for air conditioning than the rest of the world. In Canada, air conditioning use varies by province. In 2013, 55% of Canadian households reported having an air conditioner, with high use in Manitoba (80%), Ontario (78%), Saskatchewan (67%), and Quebec (54%) and lower use in Prince Edward Island (23%), British Columbia (21%), and Newfoundland and Labrador (9%). In Europe, home air conditioning is generally less common. Southern European countries such as Greece have seen a wide proliferation of home air-conditioning units in recent years. In another southern European country, Malta, it is estimated that around 55% of households have an air conditioner installed.  In China, the proportion of urban households with air conditioners increased from 8% to 70% in 9 years, from 1995 to 2004. In 2016, it was predicted that by 2031, there would be an additional 700 million air conditioners worldwide.

Process applications.

Process applications aim to provide a suitable environment for a process being carried out, regardless of internal heat and humidity loads and external weather conditions. It is the

Health effects.

In hot weather, air conditioning can prevent heat stroke, dehydration from excessive sweating and other problems related to hyperthermia. Heat waves are the most lethal type of weather phenomenon in developed countries. Air conditioning (including filtration, humidification, cooling and disinfection) can be used to provide a clean, safe, hypoallergenic atmosphere in hospital operating rooms and other environments where proper

Environmental impacts.

Power consumption and efficiency.

Production of the electricity used to operate air conditioners has an environmental impact, including the release of greenhouse gases. According to a 2015 government survey, 87% of the homes in the

Lower-energy alternatives.

Alternatives to continual air conditioning can be used

Automobile power consumption.

In an automobile, the A/C system will use around 4

Refrigerants.

The selection of the working fluids (refrigerants) has a significant impact not only on the performance of the air conditioners but on the environment as well. Most refrigerants used for air conditioning contribute to global warming, and many also deplete the ozone layer. CFCs, HCFCs, and HFCs are potent greenhouse gases when leaked to the atmosphere.  The use of CFC as a refrigerant was once common, including the refrigerants R-11 and R-12 (sold under the brand name "Freon-12"). Freon refrigerants were commonly used during the 20th century in air conditioners due

Economic effects.

Demographical.

Air conditioning caused various shifts in demography, notably that of the U.S starting from the 1970s.  First, the number of births became much less varied throughout the year. Whereas, until 1970, the birth rate in the spring was lower than during the other seasons, the introduction of air conditioning leveled out this difference at the end of the 20th

Effects in production.

First designed to benefit targeted industries such as the press as well as large factories, the invention quickly spread to

Cost of production.

The energy use for cooling in the U.S have spurted in the last 30 years from 50 to 2000 TW per hour (1 TW=

Air conditioning (often referred to as AC, A/C, or air con) is the process of removing heat and moisture from the interior of an occupied space to improve the comfort of occupants. Air conditioning can be used in both domestic and commercial environments. This process is most commonly used to achieve a more comfortable interior environment, typically for humans and other animals; however, air conditioning is also used to cool and dehumidify rooms filled with heat-producing electronic devices, such as computer servers, power amplifiers, and to display and store some delicate products, such as artwork.

空气调节是包含温度、湿度、空气清净度以及空气循环的控制系统。这与冷气机/空调供应冷气、暖气或除湿的作用原理均类似,大部分利用冷媒在压缩机的作用下,发生蒸发或凝结,从而引发周遭空气的蒸发或凝结,以达到改变温、湿度的目的。冷气机及暖气机的效率会用性能系数来表示,是输入功和提供热能(或抽出热能)的比例值,一般来说,直流马达比交流省电,变频比传统压缩机省电,因为能够节省大量的电费,直流变频型态逐渐成为市场大宗。


Definitions.

In his book "Form in Tonal Music", Douglass M. Green distinguishes between genre and form. He lists madrigal, motet, canzona, ricercar, and dance as examples of genres from the Renaissance period. To further clarify the meaning of "genre", Green writes, "Beethoven's Op. 61 and Mendelssohn's Op. 64 are identical in genre—both are violin concertos—but different in form. However, Mozart's Rondo for Piano, K. 511, and the "Agnus Dei" from his Mass, K. 317, are quite different in genre but happen to be similar in form." Some, like Peter van der Merwe, treat the terms "genre" and "style" as the same, saying that "genre" should be defined as pieces of music that share a certain style or "basic musical language."  Others, such as Allan F. Moore, state that "genre" and "style" are two separate terms, and that secondary characteristics such as subject matter can also differentiate between genres. A music genre or subgenre may also be defined by the musical techniques, the cultural context, and the content and spirit of the themes. Geographical origin is sometimes used to identify a music genre, though a single geographical category will often include a wide variety of subgenres. Timothy Laurie argues that, since the early 1980s, "genre has graduated from being a subset of popular music studies to being an almost ubiquitous framework for constituting and evaluating musical research objects".  Musicologists have sometimes classified music according to a trichotomous distinction such as Philip Tagg's "axiomatic triangle consisting of 'folk', 'art' and 'popular' musics". He explains that each of these three is distinguishable from the others according to certain criteria.  Alternatively, music can be assessed on the three dimensions of "arousal", "valence", and "depth". Arousal reflects physiological processes such as stimulation and relaxation (intense, forceful, abrasive, thrilling vs. gentle, calming, mellow), valence reflects emotion and mood processes (fun, happy, lively, enthusiastic, joyful vs. depressing, sad), and depth reflects cognitive processes (intelligent, sophisticated, inspiring, complex, poetic, deep, emotional, thoughtful vs. party music, danceable). These help explain why many people like similar songs from different traditionally segregated genres.

Art music.

Art music primarily includes classical traditions, including both contemporary and historical classical music forms. Art music exists in many parts of the world. It emphasizes formal styles that invite technical and detailed deconstruction and criticism, and demand focused attention from the listener. In Western practice, art music is considered primarily a written musical tradition, preserved in some form of music notation rather than being transmitted orally, by rote, or in recordings, as popular and traditional music usually are. Historically, most western art music has been written down using the standard forms of music notation that evolved in Europe, beginning well before the Renaissance and reaching its maturity in the Romantic period.  The identity of a "work" or "piece" of art music is usually defined by the notated version rather than by a particular performance and is primarily associated with the composer rather than the performer (though composers may leave performers with some opportunity for interpretation or improvisation). This is so particularly in the case of western classical music. Art music may include certain forms of jazz, though some feel that jazz is primarily a form of popular music. The 1960s saw a wave of avant-garde experimentation in free jazz, represented by artists such as Ornette Coleman, Sun Ra, Albert Ayler, Archie Shepp and Don Cherry. And avant-garde rock artists such as Frank Zappa, Captain Beefheart, and The Residents released art music albums.

Popular music.

Popular music is any musical style accessible to the general public and disseminated by the mass media. Musicologist and popular music specialist Philip Tagg defined the notion in the light of sociocultural and economical aspects:  Popular music, unlike art music, is (1) conceived for mass distribution to large and often socioculturally heterogeneous groups of listeners, (2) stored and distributed in non-written form, (3) only possible in an industrial monetary economy where it becomes a commodity and (4) in capitalist societies, subject to the laws of 'free' enterprise... it should ideally sell as much as possible.  Popular music is found on most commercial and public service radio stations, in most commercial music retailers and department stores, and movie and television soundtracks. It is noted on the " Billboard" charts and, in addition to singer-songwriters and composers, it involves music producers more than other genres do.  The distinction between classical and popular music has sometimes been blurred in marginal areas such as minimalist music and light classics. Background music for films/movies often draws on both traditions. In this respect, music is like fiction, which likewise draws a distinction between literary fiction and popular fiction that is not always precise.

Rock music.

Rock music is a broad genre of popular music that originated as "rock and roll" in the United States in the early 1950s, and developed into a range of different styles in the 1960s and later, particularly in the United Kingdom and in the United States.

Electronic music.

Electronic dance music saw further rise in early 21st-century pop culture due to DJs like Avicii, Calvin Harris, Daft Punk, David Guetta, Nico Bisio, Deadmau5, Marshmello, Martin Garrix, Skrillex and more.

Soul music/R&B.

Soul music became a musical genre that came to include a wide variety of R&B-based music styles from the pop R&B acts at Motown Records in Detroit, such as The Temptations, Marvin Gaye and Four Tops, to "deep soul" singers such as Percy Sledge and James Carr.

Country music.

Country music, also known as country and western (or simply country) and hillbilly music, is a genre of popular music that originated in the southern United States in the early 1920s.

Reggae.

Reggae music, originating from the late 1960s Jamaica, is a genre of music that was originally used by Jamaicans to define themselves with their lifestyle and social aspects. The meaning behind reggae songs tend to be about love, faith or a higher power, and freedom. Reggae music is important to Jamaican culture as it has been used as inspiration for many third world liberation movements. Bob Marley, an artist primarily known for reggae music, was honored by Zimbabwe's 1980 Independence celebration due to his music giving inspirations to freedom fighters. The music genre of reggae is known to incorporate different stylistic techniques form rhythm and blues, jazz, African, Caribbean, and other genres as well but what makes reggae unique are the vocals and lyrics. The vocals tend to be sung in Jamaican Patois, Jamaican English, and Iyaric dialects. The lyrics of reggae music usually tend to raise political awareness and on cultural perspectives.

Hip hop music.

Hip Hop music, also referred to as "hip hop" or "rap music", is a genre of music that was started in the United States, specifically the South Bronx in the New York City by African-American youth from the inner cities during the 1970s. It can be broadly defined as a stylized rhythmic music that commonly accompanies rapping, a rhythmic and rhyming speech that is chanted. Hip hop music derives from the hip hop culture itself, including four key elements: emceeing (MCing)/rapping, Disc jockeying (DJing) with turntablism, breakdancing and graffiti art.

Polka.

The polka is originally a Czech dance and genre of dance music familiar throughout Europe and the Americas.

Religious music.

Religious music (also sacred music) is music performed or composed for religious use or through religious influence. Gospel, spiritual, and Christian music are religious music.

Traditional and folk music.

Traditional and folk music are very similar categories. Although the traditional music is a very broad category and can include several different genres, it is widely accepted that traditional music encompasses folk music. According to the ICTM (International Council for Traditional Music), traditional music are songs and tunes that have been performed over a long period of time (usually several generations).  The folk music genre is classified as the music that is orally passed from one generation to another. Usually the artist is unknown, and there are several different versions of the same song. The genre is transmitted by singing, listening and dancing to popular songs. This type of communication allows culture to transmit the styles (pitches and cadences) as well as the context it was developed.  Culturally transmitting folk songs maintain rich evidence about the period of history when they were created and the social class in which they developed. Some examples of the Folk Genre can be seen in the folk music of England and Turkish folk music. English folk music has developed since the medieval period and has been transmitted from that time until today. Similarly, Turkish folk music relates to all the civilizations that once passed thorough Turkey, thereby being a world reference since the east–west tensions during the Early Modern Period.  Traditional folk music usually refers to songs composed in the twentieth century, which tend to be written as universal truths and big issues of the time they were composed. Artists including Bob Dylan; Peter, Paul and Mary; James Taylor; and Leonard Cohen transformed folk music to what it is known today. Newer composers such as Ed Sheeran (pop folk) and The Lumineers (American folk) are examples of contemporary folk music, which has been recorded and adapted to the new way of listening to music (online)—unlike the traditional way of orally transmitting music.  Each country in the world, in some cases each region, district and community, has its own folk music style. The different sub-divisions of folk genre are developed by each place, cultural identity and history. Because the music is developed in different places, many of the instruments are characteristic to location and population—but some are used everywhere: button or piano accordion, different types of flutes or trumpets, banjo, and ukulele. Both French and Scottish folk music use related instruments such as the fiddle, the harp and variations of bagpipes.

Automatic categorization.

Automatic methods of musical similarity detection, based on data mining and co-occurrence analysis, have been developed to classify music titles for electronic music distribution.

Emergence of new genres and sub-genres.

New genres can arise through the development of new forms and styles of music and also simply by creating a new categorization. Although it is conceivable to create a musical style with no relation to existing genres, new styles usually appear under the influence of pre-existing genres.  The genealogy of musical genres expresses, often in the form of a written chart, how new genres have developed under the influence of older ones. If two or more existing genres influence the emergence of a new one, a fusion between them can be said to have taken place. The proliferation of popular music in the 20th century has led to over 1,200 definable sub-genres of music. Examples of fusion genres include jazz fusion, which is a fusion of jazz and rock music, and country rock which is a fusion of country music and rock music.

Psychology of music preference.

Social influences on music selection.

Since music has become more easily accessible (Spotify, iTunes, YouTube, etc.), more people have begun listening to a broader and wider range of music styles. In addition, social identity also plays a large role in music preference. Personality is a key contributor for music selection. Someone who considers themselves to be a "rebel" will tend to choose heavier music styles like heavy metal or hard rock, while someone who considers themselves to be more "relaxed" or "laid back" will tend to choose lighter music styles like jazz or classical music. There are five main factors that exist that underlie music preferences that are genre-free, and reflect emotional/affective responses. These five factors are:

Individual and situational influences.

Gender.

Studies have shown that while women prefer more treble oriented music, men prefer to listen to bass heavy music. This is sometimes paired with borderline and antisocial personalities.

Age.

Age is another strong factor that contributes to musical preference. Evidence is available that shows that music preference can change as one gets older. A Canadian study showed that adolescents show greater interest in pop music artists while adults and the elderly population prefer classic genres such as rock, opera, and jazz.

A music genre is a conventional category that identifies some pieces of music as belonging to a shared tradition or set of conventions. It is to be distinguished from "musical form" and "musical style", although in practice these terms are sometimes used interchangeably.

音乐类型(英语:music genre),或称音乐流派,是对于音乐作品归属的传统性分类。它与音乐形式并不相同,尽管在现实中有时会混用。


History.

Early history and Middle Ages.

In Western society, the formal concept of a duel developed out of the medieval judicial duel and older pre-Christian practices such as the Viking Age "holmgang". In medieval society, judicial duels were fought by knights and squires to end various disputes. Countries like Germany, United Kingdom, and Ireland practiced this tradition. Judicial combat took two forms in medieval society, the feat of arms and chivalric combat. The feat of arms was used to settle hostilities between two large parties and supervised by a judge. The battle was fought as a result of a slight or challenge to one party's honor which could not be resolved by a court. Weapons were standardized and typical of a knight's armoury, for example longswords, polearms etc.; however, weapon quality and augmentations were at the discretion of the knight, for example, a spiked hand guard or an extra grip for half-swording. The parties involved would wear their own armour; for example, one knight wearing

Renaissance and early modern Europe.

During the early Renaissance, dueling established the status of a respectable gentleman and was an accepted manner to resolve disputes.  The first published "code duello", or "code of dueling", appeared in Renaissance Italy. The first formalized national code was France's, during the Renaissance.  By the 17th century, duelling had become regarded as a prerogative of the aristocracy, throughout Europe, and attempts to discourage or suppress it generally failed. For example, King

Enlightenment-era opposition.

By the late 18th century, Enlightenment era values began to influence society with new self-conscious ideas about politeness, civil behaviour and new attitudes towards violence. The cultivated art of politeness demanded that there should be no outward displays of anger or violence, and the concept of honor became more personalized.  By the 1770s the practice of dueling was increasingly coming under attack from many sections of enlightened society, as a violent relic of Europe's medieval past unsuited for modern life. As England began to industrialize and benefit from urban

Modern history.

Dueling became popular in the United States – the former United States Secretary of the Treasury Alexander Hamilton was killed in a duel against the sitting Vice President Aaron Burr in 1804. Between 1798 and the Civil War, the US Navy lost two-thirds as many officers to dueling as it did in combat at sea, including naval hero Stephen Decatur. Many of those killed or wounded were midshipmen or junior officers. Despite prominent deaths, dueling persisted because of contemporary ideals of chivalry, particularly in the South, and because of the threat of ridicule if a challenge was rejected.  By about 1770, the duel underwent a number of important changes in England. Firstly, unlike their counterparts in many continental nations, English duelists enthusiastically adopted the pistol, and sword duels dwindled. Special sets of dueling pistols were crafted for the wealthiest of noblemen for this purpose. Also, the office of'second' developed into'seconds' or 'friends' being chosen by the aggrieved parties to conduct their honor dispute. These friends would attempt to resolve a dispute upon terms acceptable to both parties and, should this fail, they would arrange and oversee the mechanics of the encounter.  In the United Kingdom, to kill in the course of a duel was formally judged as murder, but generally the courts were very lax in applying the law, as they were sympathetic to the culture of honor. This

Decline in the 19th and 20th centuries.

Duels had mostly ceased to be fought to the death by the late 19th century. The last known fatal duel in Ontario was in Perth, in 1833, when Robert Lyon challenged John Wilson to a pistol duel after a quarrel over remarks made about a local school teacher, whom Wilson married after Lyon was killed in the duel. Victoria, BC was known to have been the centre of at least two duels near the time of the gold rush. One involved a British arrival by the name of George Sloane, and an American, John Liverpool, both arriving via San Francisco in 1858. In a duel by pistols, Sloane was fatally injured and Liverpool shortly returned to the US. The fight

Legislation.

Charles I outlawed dueling in Austria-Hungary in 1917. Germany (the various states of the Holy Roman Empire) has a history of laws against dueling going back to the late medieval period, with a large amount of legislation ("Duellmandate") dating from the period after the Thirty Years' War. Prussia outlawed dueling in 1851, and the law was inherited by the "Reichsstrafgesetzbuch" of the German Empire after 1871. Pope Leo XIII in the encyclica "Pastoralis officii" (1891) asked the bishops of Germany and Austria-Hungary to impose penalties on duellists. In Nazi-era Germany, legislations on dueling were tightened in 1937. After World War II, West German authorities persecuted

Olympics.

In the late 19th and early 20th century, pistol dueling became popular as a sport in France. The duelists were armed with conventional pistols, but the cartridges had wax bullets and were without any powder

Late survivals.

Dueling culture survived in France, Italy and Latin America well into the 20th century. After World War II, duels had become rare even in France, and those that still occurred were covered in the press as eccentricities. Duels in France in this period, while still taken seriously as a matter of honor, were not fought to the death. They consisted of fencing with the épée mostly in a fixed distance with the aim of drawing blood from the opponent's arm. In 1949, former Vichy-official Jean-Louis Tixier-Vignancour fought school teacher Roger Nordmann. The last known duel in France took place in 1967, when Gaston Defferre insulted René Ribière at the French Parliament and was subsequently challenged to a duel fought with swords. René Ribière lost the duel, having been wounded twice. In Uruguay, a pistol duel was fought in 1971 between Danilo Sena and Enrique Erro, in which neither of the combatants was injured.

Rules.

Offense and satisfaction.

The traditional situation that led to a duel often happened after a perceived offense, whether real or imagined, when one party would demand satisfaction from the offender. One could signal this demand with an inescapably insulting gesture, such as throwing his glove before him.  Usually challenges were delivered in writing by one or more close friends who acted as "seconds". The challenge, written in formal language, laid out the real or imagined grievances and a demand for satisfaction. The challenged party then had the choice of accepting or refusing the challenge.

Field of honor.

The chief criteria for choosing the field of honor were isolation, to avoid discovery and interruption by the authorities; and jurisdictional ambiguity, to avoid legal consequences. Islands in rivers dividing two jurisdictions were popular dueling sites; the cliffs below Weehawken on the Hudson River where the Hamilton-Burr duel occurred were a popular field of honor for New York duellists because of the uncertainty whether New York or New Jersey jurisdiction applied.

Conditions.

At the choice of the offended party, the duel could be fought to a number of conclusions:  Under the latter conditions, one or both parties could intentionally miss in order to fulfill the conditions of the duel, without loss of either life or honor. However, doing so, known as deloping, could imply that one's opponent was not worth shooting. This practice occurred despite being expressly banned by the Code Duello of 1777. Rule XII stated: "No dumb shooting or firing in

Pistol duel.

For a pistol duel, the two would typically start at a pre-agreed length of ground, which would be measured out by the seconds and marked, often with swords stuck in the ground (referred to as "points"). At a given signal, often the dropping of a handkerchief, the principals could advance and fire at will. This latter system reduced the possibility of cheating, as neither principal had to trust the other not to turn too soon. Another

Western traditions.

Europe.

Great Britain and Ireland.

The duel arrived at the end of the 16th century with the influx of Italian honor and courtesy literature – most notably Baldassare Castiglione's "Libro del Cortegiano" (Book of the Courtier), published in 1528, and Girolamo Muzio's "Il Duello", published in 1550. These stressed the need to protect one's reputation and social mask and prescribed the circumstances under which an insulted party should issue a challenge. The word "duel" was introduced in the 1590s, modelled after Medieval Latin "duellum" (an archaic Latin form of "bellum" "war", but associated by popular etymology with "duo" "two", hence "one-on-one combat").  Soon domestic literature was

Holy Roman Empire and Germany.

In Early Modern High German, the duel was known as "Kampf", or "Kampffechten". The German dueling tradition originates in the Late Middle Ages, within the German school of fencing. In the 15th century, duels were fought between members of the nobility wearing full plate armour. During the late 16th and the 17th century,

Greece.

In the Ionian Islands in the 19th century, there was a practice of formalised fighting between men over points of honor. Knives were the weapons used in such fights. They would begin with an exchange of sexually related insults in a public place such as a tavern, and the men would fight

Poland.

In Poland duels have been known since the Middle Ages. The best known was written as late as 1919 by Wladyslaw Boziewicz. At this time duels were

Russia.

The tradition of dueling and the word "duel" itself were brought to Russia in the 17th century by adventurers in Russian service. Dueling quickly became so popular – and the number of casualties among the commanding ranks so high – that, in 1715, Emperor Peter the First was forced to forbid the practice on pain of having both duellists hanged. Despite this official ban, dueling became a significant military tradition in the Russian Empire with a detailed unwritten dueling code – which was eventually written down

Americas.

Latin America.

Duels were common in much of South America during the 20th century, although generally illegal. In Argentina, during the 18th and 19th century, it was common for "gauchos"—cowboys—to resolve their disputes in a fight using working knives called "facones". After the turn of the 19th century, when repeating handguns became more widely available, use of the facón as a close-combat weapon declined. Among the gauchos, many continued to wear the knife, though mostly as a tool. However, it was occasionally still used to settle arguments "of honor". In these situations two adversaries would attack with slashing attacks to the face, stopping when one could no longer see clearly through the blood.  In Peru there were several high-profile duels by politicians in the early part of the 20th century including one in

Colonial North America and United States.

European styles of dueling established themselves in the colonies of European states in North America. Duels were to challenge someone over a woman or to defend one's honor. In the US, dueling was used to deal with political differences and disputes and was the subject of an unsuccessful amendment to the United States Constitution in 1838. It was fairly common for politicians at that time in the United States to end disputes through duels, such as the Burr–Hamilton duel and the Jackson-Dickinson duel. Dueling has become outdated in the north since the early-19th century. Dueling in the US was not uncommon in the south and west, even after 1859, when 18 states outlawed it, but it became a thing of the past in the United States by the start of the 20th century. To this day, anyone sworn into any statewide or county office or judgeship in Kentucky must declare under oath that he or she has not participated in, acted as a second or otherwise assisted in a duel.  Historian Bertram Wyatt-Brown said of dueling in the United States:  Physician J. Marion Sims has left us a chapter describing the dueling culture in 1830s South Carolina. Crude duels were also fought to uphold personal honor in the rural American frontier, that were partly influenced by the code duello brought by Southern

Asian traditions.

India.

Duels or "niyuddha" were held in ancient India (including modern-day Pakistan and Bangladesh) for various reasons. Many kshatriya considered it shameful to die in bed, and in their old age often arranged for a "yuddha-dhan", literally meaning "combat charity". According to this practice when a warrior felt he did not have much time to live, he would go along with a few attendants and ask another king for a duel or a small scale battle. In this way he chooses his own time and manner

Indonesia.

Weapons and rules for dueling in the Indonesian archipelago vary from one culture to another. In Madura, dueling is known as "carok" and was typically practiced with the sickle or celurit. The Madurese people imbued their sickles with a "khodam", a type of mythical spirit, by a way of prayer before engaging in a duel.  The traditional form of dueling among the Bugis-Makassar community was called "sitobo lalang lipa" in which the duellists fight in a sarong. The challenger stands with a loosened sarong around him and respectfully

Japan.

In Edo period Japan, there was a tradition of dueling (, kettō) among the samurai class. On April 14, 1612

Philippines.

Dueling was a common practice in the Philippines since ancient times, and continued to be recorded during Spanish and American colonialism. In the Visayas, there is a tradition of dueling where the offended party would first "hagit" or challenge the offender. The offender would have the choice whether to accept or decline the challenge. In the past, choice of weapons was not limited. But most often, bolos, rattan canes, and knives were the preferred weapons. Duels were either first-blood, submission, or to the last man standing. Duels to death were known as "huego-todo" (without bounds). The older generation of Filipino martial artists still tell of duels which occurred during their youth.  Duels with the bolo

Duels in popular culture.

Dueling has provided themes for numerous works of popular culture.

A duel is an arranged engagement in combat between two people, with matched weapons, in accordance with agreed-upon rules. Duels in this form were chiefly practiced in early modern Europe with precedents in the medieval code of chivalry, and continued into the modern period (18th to late 19th centuries, if not beyond) especially among military officers.

决斗通常是指两个人之间使用相似的武器或徒手,在并非比赛的场合下,以武力较量分胜负来赢取对方的降伏,甚至想证明自己的信念正确或无辜等。如果在战争中常以一骑讨、一骑打、单挑等字眼,形容参与决斗的有名将士,就以个人胜负来决定战果的情形也出现过的。


History.

In 1882, Enrico Piaggio purchased land in Sestri Ponente (Genoa) to set up a timber yard. Two years later, in 1884, his 20-year-old son,, founded Piaggio & C. The company initially built locomotives and railway carriages but in 1917, towards the end of World War, Rinaldo Piaggio turned to the military sector. To begin with, the company produced MAS anti-submarine motorboats, aeroplanes and seaplanes under Ansaldo, Macchi, Caproni, and Dornier licenses but later progressed to vehicles constructed according Piaggio's own drawings.  Between 1937 and 1939 Piaggio achieved 21 world records with its aircraft and engines built at the company's new factory in Pontedera, culminating in the four-engine Piaggio P.108 bomber.  Rinaldo died in 1938, by which time Piaggio was owned by multiple shareholders within the family, along with the entrepreneur. Management of the company passed to his sons Enrico and Armando.  By 1940 Piaggio was manufacturing trains, nautical fittings, aircraft engines, aeroplanes, trucks, trams, buses, funiculars and aluminium windows and doors. The Pontedera plant was destroyed by Allied bombing and production activities were relocated to the Biella area. After the war, Enrico Piaggio decided to diversify the company's activities outside the aeronautical industry to address a perceived need for a modern, affordable mode of transport for the Italian mass market. The first attempt, based on a small motorcycle made for parachutists, was known as the MP5 and nicknamed the "Paperino" (the Italian name for Donald Duck) because of its strange shape. Ultimately Enrico Piaggio did not like it and asked Corradino D'Ascanio to redesign it.  D'Ascanio, an aeronautical engineer responsible for the design and construction of the first modern helicopter by Agusta, was not naturally enthusiastic about motorcycles, judging them to be uncomfortable and bulky, with wheels that were difficult to change after a puncture. When asked to design a motorcycle for Ferdinando Innocenti, D'Ascanio had come up with a step through scooter design but D'Ascanio and Innocenti disagreed over use of pressings rather than tubing so D'Ascanio brought his design to Piaggio. Innocenti would ultimately use D'Ascanio's original design for their Lambretta scooter.  Piaggio asked D'Ascanio to create a simple, robust and affordable vehicle. The motorcycle had to be easy to drive for both men and women, be able to carry a passenger, and not get its driver's clothes dirty. The engineer's drawings proved a significant departure from the Paperino. With the help of Mario D'Este he prepared the first Vespa project, manufactured at Piaggio newly-rebuilt Pontedera headquarters in April 1946. Piaggio launched the Vespa (Italian for "wasp") and within ten years more than a million units had been produced. The Italian language gained a new word, "vespare", meaning to go somewhere on a Vespa.

Ownership.

Vespa thrived until 1992 when Gianni Agnelli became CEO. Agnelli was already suffering from cancer and died in 2003. In 1999 Morgan Grenfell Private Equity acquired Piaggio, but hopes for a quick sale were dashed by a failed joint venture in China. In Italy, Piaggio invested 15 million euros ($19.4 million) in a new motorcycle but dropped it after building a prototype. By the end of 2002, the company had run up 577 million Euros in debt on revenues of 945 million Euros, and booked a loss of 129 million Euros.  In 2003 Piaggio's debt was reduced a 100 million Euro investment made by, a holding company of the Colaninno family. 150 million shares were also converted by creditor banks. Reflecting on his investment, said,  "A lot of people told me I was crazy. Piaggio wasn't dying. It just needed to be treated better.""  Colannino became the new chairman of Piaggio, while Dr. Rocco Sabelli becoming the managing director. Sabelli redesigned the production line according to Japanese principles so that every Piaggio scooter could be made on any assembly line. Contrary to expectations, Mr. Colaninno did not fire a single worker – a move which helped seduce the company's skeptical unions. "Everyone in a company is part of the value chain," said Colaninno. All bonuses for blue-collar workers and management were based on the same criteria: profit margins and customer satisfaction. Air conditioning was installed in the factory for the first time, increasing productivity. He also gave the company's engineers, who had been idled by the company's financial crisis, deadlines for projects. They rolled out two world firsts in 2004: a gas-electric hybrid scooter and a sophisticated tilting scooter with two wheels in front and one in back to grip the road better.  One of Piaggio's problems Mr. Colaninno couldn't fix from the inside was its scale. Even though Piaggio was the European market leader, it was dwarfed by rivals Honda and Yamaha. A year after restoring Piaggio's health, Colaninno directed Piaggio's takeover of the Italian scooter and motorcycle manufacturer Aprilia, and with it the Aprilia-owned Moto Guzzi, a storied Italian manufacturer of motorcycles.  In 2006, Piaggio floated on the Milan Stock Exchange, becoming a public company.

Production Development.

In 1956, with production of the millionth Vespa scooter, Italy had its first mass-produced motorised vehicle. Taking advantage of increased cash flow thanks to the success of the Vespa, Piaggio developed other products, including the 1957 Vespa 400, a compact passenger car.  In 1959 Piaggio came under the control of the Agnelli family, the owners of car maker Fiat SpA.  By 1960 Vespa had produced and sold 4 million units worldwide.  In 1964 the aeronautical and motorcycle divisions of Piaggio split to become two independent companies as a result of the wide ownership by Fiat in Italian industry. The aeronautical division was named IAM Rinaldo Piaggio. The aircraft company Piaggio Aero was controlled by the family of Piero Ferrari, who still hold 10% of Ferrari.  In 1969 Piaggio purchased the motorcycle company Gilera, one of the oldest European motorcycle manufacturers (founded in 1909), famous for its sporting achievements and world titles in the Motorcycle World Championship.  In 1971 a steering wheel was added to the Piaggio Ape, a model first produced in 1948, culminating in the Ape Car. Four years later, in 1975, the company made the first prototype of an electric Ape.  In 1988 the Vespa reached the milestone of 10 million units produced.  In 1996, on the fiftieth anniversary of the first model, Vespa passed 15 million units produced and the new 4-stroke Vespa ET, the first completely new Vespa for 18 years, was launched. Piaggio was still in poor financial health but its brand recognition remained strong, boosted by the appearance of the ET4 in several Hollywood films.  In 1999, in Baramati, production began on a three-wheeler Ape for the Indian domestic market.  In 2000 Piaggio and Vespa returned to the United States with the opening of the first Vespa Boutique in Los Angeles. In that same year the Piaggio Historical Museum was inaugurated in Pontedera. The museum showcases the Piaggio Historical Archive, one of the most comprehensive company archives on the industrial history of Italy.  In 2001 the Piaggio Group acquired Derbi-Nacional Motor SA, an historical Spanish brand founded in 1922 that had won 18 world titles and was a continental leader in the small displacement motorbike segment. In the same year Gilera returned to the Motorcycle World Championship and immediately won the world title in the 125 category with Manuel Poggiali.  In 2004, at the end of December, the final contract for the acquisition of the Aprilia-Moto Guzzi Group was signed. The most important European two-wheeler group is born.  In 2007 Piaggio Group officially arrives in Vietnam. The Vinh Puch plant includes R&D, welding and painting activities, as well as final assembly of the scooters, with warehouse, testing, quality control and office areas.  In 2009 the Piaggio Mp3 Hybrid makes its debut on the market which was first hybrid scooter in the world, integrating the conventional low-environmental-impact internal combustion engine with a zero-emission electric motor and combining the advantages of the two power trains.  In Baramati (State of Maharashtra), in 2012, the Piaggio Group's new plant for the production of Vespa's for the local market was opened.  In 2013 the PADC – Piaggio Advanced Design Center opened in Pasadena (California, United States). The Vespa 946 was also launched this year, along with the new Vespa Primavera, the latest evolution of the "small body" family.  In 2013 Vespa's worldwide sales numbered almost 190,000 units; in 2004 the figure stood at 58,000. In ten years of continuous progression over 1.3 million new Vespas have reached the streets of the world. Since 1946 over 18 million Vespas have been produced and sold.  In September 2017 Foton and Piaggio agreed to form a joint venture to develop and produce light commercial vehicle. Based on Foton chassis the new vehicle was sold by Piaggio Commercial Vehicle division in Europe and in all markets around the world but not in China. The vehicle is intended to be a successor of the Piaggio Porter and production is planned to start in mid-2019 in Pontedera (Italy) with all components produced by Foton in China.

"Cultural Project" Piaggio.

Piaggio's "cultural project" promotes the reconstruction and enhancement of the company's heritage and is composed by three initiatives: the Piaggio Foundation, the Historical Archives and the Piaggio Museum. In 2003 the Museum and Archives were recognised as the Best Corporate Museum and Archive by winning the Italian prize "Premio Impresa e Cultura". In 2016, under the patronage of the Italian Ministry of Culture, Piaggio received the Corporate Art Award from pptArt for its Corporate Museum.

Brands and models.

Electric scooters.

The new plug-in hybrid version of the Piaggio MP3 will be equipped with a 125 cc petrol engine and electric motor, which offers about and travels using battery power alone. This machine could be out in 2009.  Piaggio/Vespa are also developing hybrid electric scooters. There are two models in the works, based on the popular Vespa LX 50 and the beefier Piaggio X8 125.

Piaggio & C. SpA (Piaggio ) is an Italian motor vehicle manufacturer, which produces a range of two-wheeled motor vehicles and compact commercial vehicles under seven brands: Piaggio, Vespa, Gilera, Aprilia, Moto Guzzi, Derbi, and Scarabeo. Its corporate headquarters are located in Pontedera, Italy. The company was founded by Rinaldo Piaggio in 1884, initially producing locomotives and railway carriages.

比雅久(Piaggio&C. s.p.a.)是一家意大利的机车与汽车制造大厂,旗下拥有七个品牌。身为世界第四大摩托车生产商,比雅久每年生产超过60万辆摩托车,拥有五座研发中心负责各品牌的研发,至少6700位员工及管理者在全世界50个以上的国家任职。其生产的伟士牌(Vespa)机车十分闻名。


Subdivisions and their distribution.

The Caelifera include some 2,400 valid genera and about 12,000 known species. Many undescribed species probably exist, especially in tropical forests. The Caelifera have a predominantly tropical distribution (as with most Orthoptera) with fewer species known from temperate climate zones. Caelifera are divided into two infraorders: the more basal Tridactylidea and the Acrididea or grasshopper-like species. This latter name is derived from older sources, such as Imms, which placed the "short-horned grasshoppers" and locusts at the family level (Acrididae).

Affiliations.

The phylogeny of the Caelifera, is described in detail for grasshoppers, with 6 out of 8 extant superfamilies shown here as a cladogram. Like the Ensifera, Caelifera and all of its superfamilies appear to be monophyletic. The phylogeny of the Caelifera, based on mitochondrial ribosomal RNA of thirty-two taxa in six out of seven superfamilies, is shown as a cladogram. The Ensifera, Caelifera and all the superfamilies of grasshoppers except Pamphagoidea appear to be monophyletic.  In evolutionary terms, the split between the Caelifera and the Ensifera is no more recent than the Permo-Triassic boundary; the earliest insects that are certainly Caeliferans are in the extinct families Locustopseidae and Locustavidae from the early Triassic, roughly 250 million years ago. The group diversified during the Triassic and have remained important plant-eaters from that time to now. The first modern families such as the Eumastacidae, Tetrigidae and Tridactylidae appeared in the Cretaceous, though some insects that might belong to the last two of these groups are found in the early Jurassic. Morphological classification is difficult because many taxa have converged towards a common habitat type; recent taxonomists have concentrated on the internal genitalia, especially those of the male. This information is not available from fossil specimens, and the palaentological taxonomy is founded principally on the venation of the hindwings.  The Caelifera includes some 2,400 valid genera and about 11,000 known species. Many undescribed species probably exist, especially in tropical wet forests. The Caelifera have a predominantly tropical distribution with fewer species known from temperate zones, but most of the superfamilies have representatives worldwide. They are almost exclusively herbivorous and are probably the oldest living group of chewing herbivorous insects.  The most diverse superfamily is the Acridoidea, with around 8,000 species. The two main families in this are the Acrididae (grasshoppers and locusts) with a worldwide distribution, and the Romaleidae (lubber grasshoppers), found chiefly in the New World. The Ommexechidae and Tristiridae are South American, and the Lentulidae, Lithidiidae and Pamphagidae are mainly African. The Pauliniids are nocturnal and can swim or skate on water, and the Lentulids are wingless. Pneumoridae are native to Africa, particularly southern Africa, and are distinguished by the inflated abdomens of the males.

Economic significance and terminology.

A number of species, especially in the Acridoidea, are significant agricultural pests, but not all of them are locusts: a non-taxonomic term referring to species whose populations which may change morphologically when crowded and show swarming behaviour. Examples of agricultural grasshopper pests that are not called locusts include the Senegalese grasshopper and certain species in the Pyrgomorphidae, notably the variegated grasshopper ("").

The Caelifera are a suborder of orthopteran insects. They include the grasshoppers and grasshopper-like insects, as well as other superfamilies classified with them: the ground-hoppers (Tetrigoidea) and pygmy mole crickets (Tridactyloidea). The latter should not be confused with the mole crickets (Gryllotalpidae), which belong to the other Orthopteran sub-order Ensifera.

草-{}-蜢,又名蚱-{}-蜢,即锥尾亚目(学名:)昆虫的通称,在中国北方也称蛨(蚂)蚱,古称虴蛨。是蝗虫和螽斯共有的俗称,但一般多指蝗虫而言。在生物学分类上,「蚱蜢」一词可分指「菱蝗科」和「短角蝗科」的蝗虫;「菱蝗科」又称之为「蚱科」,而「短角蝗科」则又称之为「蜢科」。蝗虫属直翅目锥尾亚目草食性昆虫。