text
stringlengths 1
146k
|
|---|
Each guest recorded his solos at his own home studio and sent the tracks back to Loomis in Seattle. Critical reception Zero Order Phase was described as "a good instrumental guitar CD" by About.com reviewer Chad Bowar. He also praised Loomis stating: "excellent guitar skills [...] technical riffs, creative solos and nonstop shredding". Ryan Ogle of Blabbermouth.net said the album was "one goddamned fiery tribute to the instrumental shred lords that have inspired his [Jeff Loomis] playing". Eduardo Rivadavia of Allmusic wrote: "guitarist Jeff Loomis has unearthed the instrumental guitar hero template that was briefly made popular by Joe Satriani in the late '80s and early '90s," he also stated that "tracks like 'Shouting Fire at a Funeral,' 'Jato Unit,' and 'Devil Theory' are entrenched in the metallic music ingredients he [Jeff Loomis] is renowned for." |
'Azure Haze' and 'Sacristy', were defined as "sweeping ballads"; on the last one, Loomis was again compared with Joe Satriani, Rivadavia stated: "admittedly very Satriani-esque." Track listing Personnel Jeff Loomis – guitar, bass, keyboards, programming Neil Kernon – keyboards, programming, producer, engineer, string arrangements, mixing, fretless guitar solo on "Cashmere Shiv" Mark Arrington – drums, percussion Ron Jarzombek – guitar solo on "Jato Unit" Pat O'Brien – guitar solo on "Race Against Disaster" Michael Manring – bass on "Cashmere Shiv" Alan Douches – mastering Brian Valentino – assistant engineer Stephanie Cabral – photography References Category:2008 debut albums Category:Century Media Records albums Category:Albums produced by Neil Kernon |
Chhatarpur is an elevated station on the Yellow Line of the Delhi Metro. It is located in the Chhatarpur locality of the South West district of Delhi, India. Shree Adya Katyayani Shakti Peeth, popularly known as the Chhatarpur Temple is located near the station. The station was to be opened in June 2010, along with the other stations of the completely elevated corridor of the Yellow Line from Qutub Minar–HUDA City Centre. However, construction on the station was delayed due to land acquisition issues. To make the station operational before the 2010 Commonwealth Games, the Delhi Metro Rail Corporation adopted a special design to construct the Chhatarpur station, using pre-fabricated structures. |
The station was finally opened to public on 26 August 2010, being built in a record time of nine months. Chhatarpur is the only station in the Delhi Metro network to be made completely of steel. History Delhi Metro Rail Corporation Ltd. (DMRC) started to acquire land in Chattarpur area to construct the station since September 2006. Two hectare plot was required for constructing the main Metro station, an electrical sub station, parking space and other utilities. After having land acquisition problems in acquiring three plots for construction, DMRC decided to skip the station. But the gap between the two stations (Qutub Minar and Sultanpur) on either side of Chhatarpur would have been 2.7 km which is too long for a MRTS system. |
As the station was expected to see a ridership of about 11,723 passengers daily by 2011 in Vasant Kunj area and the Chhatarpur temple, DMRC decided to construct the station using a special design costing an additional 30 to 50% expense to construct the station within the time frame. The construction work of the station was delayed as the land for the building of the station was acquired by DMRC in October 2009 after prolonged litigation. The elevated station was constructed using a unique method using special pre-fabricated/structural steel as the conventional construction technique by concrete would have taken at least 18 to 24 months. |
The steel structures were fabricated in a factory in Gurgaon. The quality of the construction was then checked through Radiography of the joints and Dye-Penetration Tests (DPT). To ensure quality work, the welding activity was not carried at Chhatarpur and the steel structures had to be joined using bolting arrangements. The Qutub Minar-Huda City Centre corridor of the Yellow Line was made operational in June 2010 with ten stations with no stoppage at the Chhatarpur station. The work on the station was completed by August 2010 and the mandatory clearance was given by R K Kardam, the Commissioner of Metro rail safety (CMRS) on 25 August 2010. |
The Chhatarpur station was finally opened to public on 26 August 2010, built in a record time of 9 months. Facilities The Chhatarpur station is an elevated station built in an area of 26,000 sq. m. The station has a receiving sub-station (RSS) built in 1 hectare area and the largest parking area in the Delhi Metro network. The parking lot has been built over about 12,000 square metres. However, only about 4,000 square metres of parking area was opened for use where 800 two wheelers and 200 cars can be parked. The rest of the parking area will be opened in a phased manner. |
The station caters to the localities of Chhatarpur, Mehrauli village, Kishangarh Village and Vasant Kunj area and also the huge number of devotees who visit Chhatarpur temple. The expected ridership of this station as per the detailed project report (DPR) made by the DMRC is 11,723 in 2011. List of available ATMs at Chhatarpur metro station are: RBL Bank Canara Bank HDFC Bank SBI Station layout Gallery See also List of Delhi Metro stations Transport in Delhi Delhi Metro Rail Corporation Delhi Suburban Railway Delhi Transport Corporation South Delhi National Capital Region (India) List of rapid transit systems List of metro systems References External links Delhi Metro Rail Corporation Ltd. (Official site) Delhi Metro Annual Reports UrbanRail.Net – descriptions of all metro systems in the world, each with a schematic map showing all stations. |
Category:Delhi Metro stations Category:Railway stations opened in 2010 Category:Railway stations in South Delhi district Category:2010 establishments in India |
Oenocarpus bacaba is an economically important monoecious fruiting palm native to South America and the Amazon Rainforest, which has edible fruits. This plant is cited in Flora Brasiliensis by Carl Friedrich Philipp von Martius. It can reach up to 20–25 metres tall and 15–25 cm in diameter. It grows in well-drained sandy soils of the Amazon basin. Names It is called bacaba açu, bacaba-de-leque, and bacaba verdadeira in Brazil, ungurauy in Peru, camon in French Guiana, koemboe in Suriname, and manoco and punáma in Colombia. The Portuguese "bacaba" and the Spanish "milpesos" (or "palma milpesos") often denote this species, but may refer to any Oenocarpus palm. |
In English it has been called Turu palm. Fruit Bacaba produces more fruits than any other palm in central Amazonia, averaging around 2500 per bunch. Bunches usually weigh about 3–4 kg, but can weigh up to 10 kg. The fruit is a drupe weighing up to 3.0 grams. Propagation is by seeds that germinate in 60–120 days, with slow growth. Production begins when the tree is 3–4 meters high, after about 6 years. The fruits has a rounded dark red to purple shell and creamy white flesh, rich in oil of a pale yellow color. Bacaba fruit are cooked to prepare a juice which is much sought after by local people, though generally less popular than açaí. |
Bacaba fruit is agreeable and its flavor is reminiscent of avocado. The fruits are rich in natural phenols, especially in flavonoids and their red color is due to cyanidin hexosides. Cultivation The tree grows in well-drained sandy soils of the Amazon basin. Form optimal germination, seeds should be planted at a depth of 2 cm in sand and vermiculite, and the temperature kept around 30 °C. Seeds should be kept moist but rather than wet. Other information The seeds and the remains of the macerated pulp are fed to pigs and poultry. Leaves are used for house interiors while trunks provide tough wood suitable for construction. |
The city of Bacabal in Maranhão was so called because of the large amount of existing Bacaba fruit there. References Further reading Schultes, Richard E. (1974). Palms and religion in the northwest Amazon. Principes 18 (1): 3-21. Astrocaryum vulgare, Bactris gasipaes, Euterpe oleracea, E. precatoria, Leopoldinia piassaba, Maximiliana martiana, Oenocarpus bacaba, Socratea exorrhiza External links Oenocarpus bacaba photos Flora Brasiliensis: Oenocarpus bacaba bacaba Category:Trees of the Amazon Category:Tropical fruit Category:Trees of Brazil Category:Trees of Peru Category:Taxa named by Carl Friedrich Philipp von Martius |
Gaelen Foley is an American author best known for writing romance novels set in the Regency era. She has also been self-publishing middle grade fantasy books under the pen name E.G. Foley since 2012. Her books have been in the USA Today bestseller list regularly since 2000 and the New York Times bestseller list since 2008. Gaelen’s novels have been translated into 20+ foreign languages and have sold millions of copies worldwide. Biography Gaelen Foley is the eldest of four sisters. She holds a B.A. in English literature with a minor in philosophy from the State University of New York at Fredonia. |
After college, Foley wrote as much as she could in her free time while working a variety of odd jobs, including: waitressing, library assistant, and medical office staff. In that time, she wrote four full-length manuscripts, honing her craft, before the fifth was picked up by one of the Big Five (publishers), Random House. In 1998 her first romance novel, The Pirate Prince, was published and since then she has penned some 35+ novels. |
Awards National Readers' Choice Booksellers' Best Golden Leaf Award of Excellence Laurie Romantic Times Reviewers' Choice Award for Best First Historical The Holt Medallion Bibliography Writing as Gaelen Foley Ascension Trilogy The Pirate Prince (1998) Princess (1999) Prince Charming (2000) Knight Miscellany The Duke (2000) Lord of Fire (2002) Lord of Ice (2002) Lady of Desire (2003) Devil Takes a Bride (2004) One Night of Sin (2005) His Wicked Kiss (2006) Spice Trilogy Her Only Desire (2007) Her Secret Fantasy (2007) Her Every Pleasure (2008) Inferno Club My Wicked Marquess (2009) My Dangerous Duke (2010) My Irresistible Earl (2011) My Ruthless Prince (2012) My Scandalous Viscount (2012) My Notorious Gentleman (2013) The Secrets of a Scoundrel (2014) Age of Heroes Paladin’s Prize (2015) Harmony Falls Dream of Me (2016) Belong to Me (2017) Moonlight Square One Moonlit Night (2015) Duke of Scandal (2015) Duke of Secrets (2017) Duke of Storm (2017) Duke of Shadows (2018) Writing as E.G. |
Foley The Gryphon Chronicles The Lost Heir (2012) Jake & The Giant (2013) The Dark Portal (2013) The Gingerbread Wars (2013) Rise of Allies (2014) Secrets of the Deep (2016) The Black Fortress 50 States of Fear The Haunted Plantation (2014) Bringing Home Bigfoot (2014) Leader of the Pack (2014) The Dork & The Deathray (2015) References http://www.gaelenfoley.com External links Official site Category:20th-century American novelists Category:21st-century American novelists Category:American romantic fiction writers Category:American women novelists Category:Year of birth missing (living people) Category:Living people Category:20th-century American women writers Category:21st-century American women writers |
A commutator is a rotary electrical switch in certain types of electric motors and electrical generators that periodically reverses the current direction between the rotor and the external circuit. It consists of a cylinder composed of multiple metal contact segments on the rotating armature of the machine. Two or more electrical contacts called "brushes" made of a soft conductive material like carbon press against the commutator, making sliding contact with successive segments of the commutator as it rotates. The windings (coils of wire) on the armature are connected to the commutator segments. Commutators are used in direct current (DC) machines: dynamos (DC generators) and many DC motors as well as universal motors. |
In a motor the commutator applies electric current to the windings. By reversing the current direction in the rotating windings each half turn, a steady rotating force (torque) is produced. In a generator the commutator picks off the current generated in the windings, reversing the direction of the current with each half turn, serving as a mechanical rectifier to convert the alternating current from the windings to unidirectional direct current in the external load circuit. The first direct current commutator-type machine, the dynamo, was built by Hippolyte Pixii in 1832, based on a suggestion by André-Marie Ampère. Commutators are relatively inefficient, and also require periodic maintenance such as brush replacement. |
Therefore, commutated machines are declining in use, being replaced by alternating current (AC) machines, and in recent years by brushless DC motors which use semiconductor switches. __TOC__ Principle of operation A commutator consists of a set of contact bars fixed to the rotating shaft of a machine, and connected to the armature windings. As the shaft rotates, the commutator reverses the flow of current in a winding. For a single armature winding, when the shaft has made one-half complete turn, the winding is now connected so that current flows through it in the opposite of the initial direction. In a motor, the armature current causes the fixed magnetic field to exert a rotational force, or a torque, on the winding to make it turn. |
In a generator, the mechanical torque applied to the shaft maintains the motion of the armature winding through the stationary magnetic field, inducing a current in the winding. In both the motor and generator case, the commutator periodically reverses the direction of current flow through the winding so that current flow in the circuit external to the machine continues in only one direction. Simplest practical commutator Practical commutators have at least three contact segments, to prevent a "dead" spot where two brushes simultaneously bridge only two commutator segments. Brushes are made wider than the insulated gap, to ensure that brushes are always in contact with an armature coil. |
For commutators with at least three segments, although the rotor can potentially stop in a position where two commutator segments touch one brush, this only de-energizes one of the rotor arms while the others will still function correctly. With the remaining rotor arms, a motor can produce sufficient torque to begin spinning the rotor, and a generator can provide useful power to an external circuit. Ring/segment construction A commutator consists of a set of copper segments, fixed around the part of the circumference of the rotating machine, or the rotor, and a set of spring-loaded brushes fixed to the stationary frame of the machine. |
Two or more fixed brushes connect to the external circuit, either a source of current for a motor or a load for a generator. Commutator segments are connected to the coils of the armature, with the number of coils (and commutator segments) depending on the speed and voltage of the machine. Large motors may have hundreds of segments. Each conducting segment of the commutator is insulated from adjacent segments. Mica was used on early machines and is still used on large machines. Many other insulating materials are used to insulate smaller machines; plastics allow quick manufacture of an insulator, for example. |
The segments are held onto the shaft using a dovetail shape on the edges or underside of each segment. Insulating wedges around the perimeter of each segment are pressed so that the commutator maintains its mechanical stability throughout its normal operating range. In small appliance and tool motors the segments are typically crimped permanently in place and cannot be removed. When the motor fails it is discarded and replaced. On large industrial machines (say, from several kilowatts to thousands of kilowatts in rating) it is economical to replace individual damaged segments, and so the end-wedge can be unscrewed and individual segments removed and replaced. |
Replacing the copper and mica segments is commonly referred to as "refilling". Refillable dovetailed commutators are the most common construction of larger industrial type commutators, but refillable commutators may also be constructed using external bands made of fiberglass (glass banded construction) or forged steel rings (external steel shrink ring type construction and internal steel shrink ring type construction). Disposable, molded type commutators commonly found in smaller DC motors are becoming increasingly more common in larger electric motors. Molded type commutators are not repairable and must be replaced if damaged. In addition to the commonly used heat, torque, and tonnage methods of seasoning commutators, some high performance commutator applications require a more expensive, specific "spin seasoning" process or over-speed spin-testing to guarantee stability of the individual segments and prevent premature wear of the carbon brushes. |
Such requirements are common with traction, military, aerospace, nuclear, mining, and high speed applications where premature failure can lead to serious negative consequences. Friction between the segments and the brushes eventually causes wear to both surfaces. Carbon brushes, being made of a softer material, wear faster and may be designed to be replaced easily without dismantling the machine. Older copper brushes caused more wear to the commutator, causing deep grooving and notching of the surface over time. The commutator on small motors (say, less than a kilowatt rating) is not designed to be repaired through the life of the device. |
On large industrial equipment, the commutator may be re-surfaced with abrasives, or the rotor may be removed from the frame, mounted in a large metal lathe, and the commutator resurfaced by cutting it down to a smaller diameter. The largest of equipment can include a lathe turning attachment directly over the commutator. Brush construction Early machines used brushes made from strands of copper wire to contact the surface of the commutator. However, these hard metal brushes tended to scratch and groove the smooth commutator segments, eventually requiring resurfacing of the commutator. As the copper brushes wore away, the dust and pieces of the brush could wedge between commutator segments, shorting them and reducing the efficiency of the device. |
Fine copper wire mesh or gauze provided better surface contact with less segment wear, but gauze brushes were more expensive than strip or wire copper brushes. Modern rotating machines with commutators almost exclusively use carbon brushes, which may have copper powder mixed in to improve conductivity. Metallic copper brushes can be found in toy or very small motors, such as the one illustrated above, and some motors which only operate very intermittently, such as automotive starter motors. Motors and generators suffer from a phenomenon known as 'armature reaction', one of the effects of which is to change the position at which the current reversal through the windings should ideally take place as the loading varies. |
Early machines had the brushes mounted on a ring that was provided with a handle. During operation, it was necessary to adjust the position of the brush ring to adjust the commutation to minimise the sparking at the brushes. This process was known as 'rocking the brushes'. Various developments took place to automate the process of adjusting the commutation and minimizing the sparking at the brushes. One of these was the development of 'high resistance brushes', or brushes made from a mixture of copper powder and carbon. Although described as high resistance brushes, the resistance of such a brush was of the order of milliohms, the exact value dependent on the size and function of the machine. |
Also, the high resistance brush was not constructed like a brush but in the form of a carbon block with a curved face to match the shape of the commutator. The high resistance or carbon brush is made large enough that it is significantly wider than the insulating segment that it spans (and on large machines may often span two insulating segments). The result of this is that as the commutator segment passes from under the brush, the current passing to it ramps down more smoothly than had been the case with pure copper brushes where the contact broke suddenly. |
Similarly the segment coming into contact with the brush has a similar ramping up of the current. Thus, although the current passing through the brush was more or less constant, the instantaneous current passing to the two commutator segments was proportional to the relative area in contact with the brush. The introduction of the carbon brush had convenient side effects. Carbon brushes tend to wear more evenly than copper brushes, and the soft carbon causes far less damage to the commutator segments. There is less sparking with carbon as compared to copper, and as the carbon wears away, the higher resistance of carbon results in fewer problems from the dust collecting on the commutator segments. |
The ratio of copper to carbon can be changed for a particular purpose. Brushes with higher copper content perform better with very low voltages and high current, while brushes with a higher carbon content are better for high voltage and low current. High copper content brushes typically carry 150 to 200 amperes per square inch of contact surface, while higher carbon content only carries 40 to 70 amperes per square inch. The higher resistance of carbon also results in a greater voltage drop of 0.8 to 1.0 volts per contact, or 1.6 to 2.0 volts across the commutator. Brush holders A spring is typically used with the brush, to maintain constant contact with the commutator. |
As the brush and commutator wear down, the spring steadily pushes the brush downwards towards the commutator. Eventually the brush wears small and thin enough that steady contact is no longer possible or it is no longer securely held in the brush holder, and so the brush must be replaced. It is common for a flexible power cable to be directly attached to the brush, because current flowing through the support spring would cause heating, which may lead to a loss of metal temper and a loss of the spring tension. When a commutated motor or generator uses more power than a single brush is capable of conducting, an assembly of several brush holders is mounted in parallel across the surface of the very large commutator. |
This parallel holder distributes current evenly across all the brushes, and permits a careful operator to remove a bad brush and replace it with a new one, even as the machine continues to spin fully powered and under load. High power, high current commutated equipment is now uncommon, due to the less complex design of alternating current generators that permits a low current, high voltage spinning field coil to energize high current fixed-position stator coils. This permits the use of very small singular brushes in the alternator design. In this instance, the rotating contacts are continuous rings, called slip rings, and no switching happens. |
Modern devices using carbon brushes usually have a maintenance-free design that requires no adjustment throughout the life of the device, using a fixed-position brush holder slot and a combined brush-spring-cable assembly that fits into the slot. The worn brush is pulled out and a new brush inserted. Brush contact angle The different brush types make contact with the commutator in different ways. Because copper brushes have the same hardness as the commutator segments, the rotor cannot be spun backwards against the ends of copper brushes without the copper digging into the segments and causing severe damage. Consequently, strip/laminate copper brushes only make tangential contact with the commutator, while copper mesh and wire brushes use an inclined contact angle touching their edge across the segments of a commutator that can spin in only one direction. |
The softness of carbon brushes permits direct radial end-contact with the commutator without damage to the segments, permitting easy reversal of rotor direction, without the need to reorient the brush holders for operation in the opposite direction. Although never reversed, common appliance motors that use wound rotors, commutators and brushes have radial-contact brushes. In the case of a reaction-type carbon brush holder, carbon brushes may be reversely inclined with the commutator so that the commutator tends to push against the carbon for firm contact. The commutating plane The contact point where a brush touches the commutator is referred to as the commutating plane. |
To conduct sufficient current to or from the commutator, the brush contact area is not a thin line but instead a rectangular patch across the segments. Typically the brush is wide enough to span 2.5 commutator segments. This means that two adjacent segments are electrically connected by the brush when it contacts both. Compensation for stator field distortion Most introductions to motor and generator design start with a simple two-pole device with the brushes arranged at a perfect 90-degree angle from the field. This ideal is useful as a starting point for understanding how the fields interact but it is not how a motor or generator functions in actual practice. |
In a real motor or generator, the field around the rotor is never perfectly uniform. Instead, the rotation of the rotor induces field effects which drag and distort the magnetic lines of the outer non-rotating stator. The faster the rotor spins, the further this degree of field distortion. Because a motor or generator operates most efficiently with the rotor field at right angles to the stator field, it is necessary to either retard or advance the brush position to put the rotor's field into the correct position to be at a right angle to the distorted field. These field effects are reversed when the direction of spin is reversed. |
It is therefore difficult to build an efficient reversible commutated dynamo, since for highest field strength it is necessary to move the brushes to the opposite side of the normal neutral plane. These effects can be mitigated by a Compensation winding in the face of the field pole that carries armature current. The effect can be considered to be analogous to timing advance in an internal combustion engine. Generally a dynamo that has been designed to run at a certain fixed speed will have its brushes permanently fixed to align the field for highest efficiency at that speed. Further compensation for self-induction Self-induction – The magnetic fields in each coil of wire join and compound together to create a magnetic field that resists changes in the current, which can be likened to the current having inertia. |
In the coils of the rotor, even after the brush has been reached, currents tend to continue to flow for a brief moment, resulting in a wasted energy as heat due to the brush spanning across several commutator segments and the current short-circuiting across the segments. Spurious resistance is an apparent increase in the resistance in the armature winding, which is proportional to the speed of the armature, and is due to the lagging of the current. To minimize sparking at the brushes due to this short-circuiting, the brushes are advanced a few degrees further yet, beyond the advance for field distortions. |
This moves the rotor winding undergoing commutation slightly forward into the stator field which has magnetic lines in the opposite direction and which oppose the field in the stator. This opposing field helps to reverse the lagging self-inducting current in the stator. So even for a rotor which is at rest and initially requires no compensation for spinning field distortions, the brushes should still be advanced beyond the perfect 90-degree angle as taught in so many beginners textbooks, to compensate for self-induction. Limitations and alternatives Although direct current motors and dynamos once dominated industry, the disadvantages of the commutator have caused a decline in the use of commutated machines in the last century. |
These disadvantages are: The sliding friction between the brushes and commutator consumes power, which can be significant in a low power machine. Due to friction, the brushes and copper commutator segments wear down, creating dust. In small consumer products such as power tools and appliances the brushes may last as long as the product, but larger machines require regular replacement of brushes and occasional resurfacing of the commutator. So commutated machines are not used in low particulate or sealed applications or in equipment that must operate for long periods without maintenance. The resistance of the sliding contact between brush and commutator causes a voltage drop called the "brush drop". |
This may be several volts, so it can cause large power losses in low voltage, high current machines. Alternating current motors, which do not use commutators, are much more efficient. There is a limit to the maximum current density and voltage which can be switched with a commutator. Very large direct current machines, say, more than several megawatts rating, cannot be built with commutators. The largest motors and generators are all alternating-current machines. The switching action of the commutator causes sparking at the contacts, posing a fire hazard in explosive atmospheres, and generating electromagnetic interference. With the wide availability of alternating current, DC motors have been replaced by more efficient AC synchronous or induction motors. |
In recent years, with the widespread availability of power semiconductors, in many remaining applications commutated DC motors have been replaced with "brushless direct current motors". These don't have a commutator; instead the direction of the current is switched electronically. A sensor keeps track of the rotor position and semiconductor switches such as transistors reverse the current. Operating life of these machines is much longer, limited mainly by bearing wear. Repulsion induction motors These are single-phase AC-only motors with higher starting torque than could be obtained with split-phase starting windings, before high-capacitance (non-polar, relatively high-current electrolytic) starting capacitors became practical. They have a conventional wound stator as with any induction motor, but the wire-wound rotor is much like that with a conventional commutator. |
Brushes opposite each other are connected to each other (not to an external circuit), and transformer action induces currents into the rotor that develop torque by repulsion. One variety, notable for having an adjustable speed, runs continuously with brushes in contact, while another uses repulsion only for high starting torque and in some cases lifts the brushes once the motor is running fast enough. In the latter case, all commutator segments are connected together as well, before the motor attains running speed. Once at speed, the rotor windings become functionally equivalent to the squirrel-cage structure of a conventional induction motor, and the motor runs as such. |
Laboratory commutators Commutators were used as simple forward-off-reverse switches for electrical experiments in physics laboratories. There are two well-known historical types: Ruhmkorff commutator This is similar in design to the commutators used in motors and dynamos. It was usually constructed of brass and ivory (later ebonite). Pohl commutator This consisted of a block of wood or ebonite with four wells, containing mercury, which were cross-connected by copper wires. The output was taken from a pair of curved copper wires which were moved to dip into one or other pair of mercury wells. Instead of mercury, ionic liquids or other liquid metals could be used. |
See also Armature (electrical engineering) Slip ring Rotary transformer Mercury swivel commutator Brushless motor :File:Kommutator animiert.gif Patents Elihu Thomson - - Commutators for Dynamo Electric Machines - 1881 June 7. Henry Jacobs - - Commutator for Magneto Electric Machines - 1881 September 6. Frank. B. Rae & Clarence. L. Healy - - Commutator For Dynamo or Magneto Electric Machines - 1884 February 26. Nikola Tesla - - Commutator for Dynamo Electric Machines - 1886 January 26. Thomas E. Adams - - Commutator for Dynamo-Electric Machines - 1886 April 27. Nikola Tesla - - Commutator for Dynamo Electric Machines - 1888 May 15. |
References External links "Commutator and Brushes on DC Motor". HyperPhysics, Physics and Astronomy, Georgia State University. "PM Brushless Servo Motor Feedback Commutation Series – Part 1 Commutation Alignment – Why It Is Important." Mitchell Electronics. "PM Brushless Servo Motor Feedback Commutation Series – Part 2 Commutation Alignment – How It Is Accomplished." Mitchell Electronics. Category:Electric motors Category:Electrical components Category:Electrical power connectors Category:Electric power conversion |
The Eurofighter Typhoon is in service with seven nations: United Kingdom, Germany, Italy, Spain, Saudi Arabia, Oman and Austria. It has been ordered by Kuwait and Qatar, with orders for all eight customers still pending as of September 2017. The aircraft has, as of 2016, been provided in a basic air-defense form and has been upgraded to newer production standards which include internal IRST, air-to-ground precision strike capability (with Royal Air Force Typhoons participating in air strikes destroying tanks in Libya in 2011 as their combat debut), and HMSS (helmet-mounted symbology system) helmets. |
Most of the major systems including the CAPTOR radar and the Defence Aids Sub-System (DASS) are expected to be improved and updated over time, with the radar being updated to an AESA, being the CAPTOR-E/CAESAR, of which the Kuwait Air Force will be the inaugural operator, with first deliveries of their 28 new-built aircraft to commence in 2019. Development aircraft Seven development aircraft (DA) were built with varying equipment fits and flight test roles. DA1 DA1's main role was handling characteristics and engine performance. DA1 was assembled in 1992 and first flew on 27 March 1994 with Luftwaffe serial 98+29. |
The military evaluation phase commenced in 1996. In 1997 after 123 flights, DA1's RB199 engines were replaced by EJ200s, it also was refitted with the Martin-Baker Mk.16A ejector seat and a full avionics fit. Following these modifications it rejoined the flight test programme in 1999. Following the loss of DA6, DA1 was transferred to Spain to undertake the remaining development work including IRIS-T trials. The aircraft was retired on 21 December 2005, eleven years, eight months, and 24 days after its first flight. It is on display at the Flugwerft Schleißheim (external site of the Deutsches Museum) near Munich, Germany. |
DA2 DA2 undertook envelope expansion, flight control assessment and load trials. The aircraft first flew on 6April 1994 as ZH588. The flight control assessment included development of the Eurofighter's "carefree handling". On 23 December 1997 DA2 became the first Eurofighter to achieve Mach2 and in January 1998 undertook refuelling trials with a RAF VC10. Like DA1, DA2 was upgraded in 1998 with new engines, ejector seat and avionics and rejoined the test programme in August. In 2000 the aircraft was covered with 490 pressure transducers; due to the fact that they were covered by black pads and had associated wiring the aircraft was painted in a gloss black scheme. |
The pressure transducers measured the effects of various weapons loads and external fuel tanks. In 2002 the aircraft undertook ASRAAM trials, completed carefree handling trials and commenced DASS decoy trials. Now retired and on display in the Milestones of Flight Gallery at the RAF Museum at Hendon. DA3 Weapons systems development. DA4 Radar and avionics development, now on display at the Imperial War Museum Duxford. In the process of being moved to Newark Air Museum, Nottinghamshire. DA5 Radar and avionics development, being upgraded to Tranche 2 standard. DA6 Airframe development and handling. DA6 was lost in a crash in Spain in November 2002 after both engines failed. |
EADS Germany's DA1 was transferred to EADS-CASA. DA7 Navigation, avionics and missile carriage. Now retired in Cameri IAF. Instrumented production aircraft The instrumented production aircraft (IPA) are five production standard aircraft fitted with telemetry instruments for dedicated flight testing and further systems development. IPA1 Defensive Aids Sub System (DASS). IPA2 Air-to-surface weapons integration. IPA3 Air-to-air weapons integration. IPA4 Air-to-surface weapons integration and environmental development. IPA5 Air-to-surface and air-to-air weapons integration. IPA6 Converted Series Production Aircraft (BS031)—Tranche 2 Computer Systems. IPA7 Converted Series Production Aircraft (GS0029)—Full Tranche 2 Standard. IPA8 E-Scan radar, enhanced weapon integration and improvements to mission equipment. Series production aircraft These are the operational and training aircraft. |
The model is known as Typhoon in the United Kingdom and export markets and as EF-2000 in Germany, Italy and Spain. However, all Italian aircraft carry the "Typhoon" logo on their tails. Tranche 1 Initial Operational Capability, Basic Air Defence Capability Block 2 Air-to-air capabilities Block 5 Air-to-air and air-to-ground capabilities, Final Operational Capability (FOC) standard. All Tranche1 aircraft are being upgraded to Block5 capability through the Retrofit 2 (R2) programme. |
Tranche 2 Block 8 New hardware standard with new mission computer Block 10 Enhanced Operational Capability (EOC) 1, improved DASS, IFF Mode 5, Rangeless ACMI Air/Air—AIM-120C-5 AMRAAM, IRIS-T digital Air/Ground—GBU-24, GPS-guided weapons, ALARM, Paveway III & IV, Rafael LITENING III Block 15 EOC 2 Air/Air—METEOR, Air/Ground—TAURUS, Storm Shadow, Brimstone Block 20 EOC 3 Tranche 3A Latest production standard incorporating EOC 3 and hardware support for EOC 4 Conformal fuel tanks, fibre optic cabling and computer upgrade, AESA Radar, defensive system upgrades Air/Ground—SPEAR 3, Marte-ER, LITENING IV & V Operators Italian Air Force aircraft As of July 2006 the Italian Air Force (Aeronautica Militare Italiana) had one EF-2000 wing, 4º Stormo (4th Wing), which received its first aircraft on 19 February 2004. |
The 36º Stormo received its first Typhoon on 1October 2007. By 2018 the Italian Air Force had three Eurofighter wings. Spanish Air Force aircraft As of December 2006 the Spanish Air Force (Ejército del Aire) has one squadron of aircraft. The first aircraft was delivered to Wing 11 in October 2003 at Moron airbase, Spain. In Spanish service, the aircraft is designated the C.16 Typhoon. Luftwaffe aircraft As of October 2006 Germany had two active EF-2000 fighter wings, Jagdgeschwader 73 and Jagdgeschwader 74. JG 73 began converting to the Eurofighter in April 2004. JG 74 received its first aircraft on 25 June 2006. |
Royal Air Force aircraft The Typhoon replaced the RAF's Tornado F3 (fighter) and Jaguar (ground attack) forces. They will equip five front-line squadrons, one front-line flight and one reserve squadrons, the Operational Conversion Unit (OCU). Typhoon T1 The Typhoon T1 is a Tranche 1, batch 1 two-seat trainer. The first Typhoon T1 is one of the Instrumented Production Aircraft (IPA1) and remains part of the BAE fleet. The aircraft's maiden flight was on April 15, 2002. The official in service date for the first RAF Typhoon T1, serial ZJ803, was June 30, 2003. Formal delivery occurred on December 18 at which point 17 Sqn began a full flying programme. |
The first squadrons, No. 17 OEU and No. 29 OCU Sqns, moved to RAF Coningsby in 2005 to begin establishing an initial operational capability (IOC). In 2001, it was announced that the Royal Air Force (RAF) would not use the aircraft's internal 27 mm Mauser cannon. This was due to a desire to save money by removing gun support costs, ammunition stocks, training costs, etc. The gun was also deemed unnecessary since the missile armament was believed to be adequate in the Typhoon's fighter role. However, because removal of the cannon would affect the aircraft's flight characteristics, requiring modification of the aircraft's flight software the RAF decided all its Typhoons would be fitted with the cannon but that it would not be used or supported. |
The service argued that this would save money by reducing the requirement for ground equipment, removing training costs and avoiding the fatigue effects of firing the cannon. The RAF maintained the option to activate the cannons at very short notice were operational requirements to change. However, in a third change of policy, the Daily Telegraph reported on 3October 2006 that the RAF will fully utilise the cannon. Typhoon T1A Typhoon T1As are Tranche 1, batch 2 two-seat trainers. There would not normally be a different designation for a different aircraft batch; however, the Batch2 aircraft has a fuel system modification to fix a fuel gauge problem identified in the development aircraft fleet. |
Typhoon F2 The F2 is the single-seat fighter variant. The first F2 is IPA5 and also remains with BAE, its first flight was June 6, 2002. The first operational squadron, No. 3, formed at RAF Cottesmore on March 31, 2006 and moved to its new base RAF Coningsby the following day. No. 11 squadron, the second operational squadron received its first aircraft (ZJ931) on October 9, 2006. As of June 2018, the RAF had bought 53 Tranche 1 Typhoons. The UK agreed to approve production of "Tranche 2" in December 2004, this tranche will see the RAF receive a further 89 aircraft, bringing its Typhoon inventory to 144. |
This followed protracted negotiations regarding the early introduction of ground attack capabilities of the aircraft and hence its swing-role capability. While this was always planned it was intended to come at a much later date. Typhoon FGR4 Single-seat Block 5 or later aircraft (built or upgraded from F2) are known as Typhoon FGR4s. The new mark number represents the increased capabilities of the Block 5 aircraft (fighter/ground attack/reconnaissance). The FGR4 has from June 2008 achieved the required standard for multi-role operations. Typhoon T3 Two-seat Block 5 or later aircraft (built or upgraded from T1) are known as Typhoon T3s. As of June 2018, the RAF has 67 Tranche 2 Typhoons and has contracted to purchase 40 Tranche3 Typhoons. |
107 Tranche2 and3 Typhoons will be modified via "Project Centurion", allowing them to utilise Meteor missiles, Brimstone and Storm Shadow missiles. 24 Tranche1 Typhoons will be retained for UK Quick Reaction Alert purposes, and will not be modified under Centurion. No. IX Squadron, based at RAF Lossiemouth, retains the Tranche1 Typhoon for QRA purposes but also serves the purpose of acting as an aggressor aircraft, similar to that of the USAF Lockheed Martin F-16 Fighting Falcon. These aircraft work in conjunction with the 100 Squadron BAe Hawk T.1 aircraft based at RAF Leeming, providing air combat training and dogfight training to RAF and Royal Navy pilots. |
Proposed versions Navalised Typhoon Owing to the withdrawal of France from the Eurofighter 2000 project, in part due to France's desire to have a greater role in the development and marketing of the aircraft, the pursuit of a naval Typhoon has never seriously been considered. |
However, a navalised variant of the aircraft was first proposed in the late 1990s as a potential solution to the UK Royal Navy's need for a Future Carrier-Borne Aircraft (FCBA) for its new (Queen Elizabeth-class) aircraft carriers, In January 2001, the UK Ministry of Defence formally discounted the option of a navalised Eurofighter for its new aircraft carriers, in favour of the STOVL ('B') variant of the F-35 Joint Strike Fighter, which (at that time) promised to be a capable, low-cost and more stealthy aircraft that would enter into service circa 2012—a date that tied in well with the in-service date for the new UK aircraft carriers as it stood at that time. |
It was rejected by the United Kingdom on "cost effectiveness grounds". , the navalised Typhoon remained only a proposal but there has been some interest expressed by other nations, such as India, in adapting the Typhoon for aircraft carrier operations. The proposed variant design would enable the Typhoon to operate from carriers on a Short Take-Off but Arrested Recovery (STOBAR) basis, using a 'ski jump' ramp for aircraft launch and arresting gear for conventional landing. In February 2011, BAE debuted a navalised Typhoon in response to the Indian tender. The model offered is STOBAR capable, corresponding to the Indian Navy's future aircraft carrier, . |
The changes needed to enable the Typhoon to launch by ski-jump and recover by arrestor hook added about 500 kg to the airframe, however this is now thought to be substantially more given the Typhoons's "unfriendly" design in terms of adapting the airframe to suit sustained naval operations. If the Indian Navy pursues a catapult launch carrier, the Typhoon is completely uncompetitive against tender rivals (e.g. Rafale and Super Hornet) since meeting "...catapult requirements would add too much weight to the aircraft, blunt performance and add substantially to modification costs". Typhoon ECR On 5 November 2019, Kurt Rossner, Head of Combat Aircraft Systems at Airbus proposed an Electronic Combat Role (ECR)-SEAD capability for the aircraft. |
The Typhoon ECR would be configured with two Escort Jammer pods under the wings and two Emitter Location Systems at the wingtips. Armament configuration would include four MBDA Meteor, two IRIS-T and six SPEAR-EW in addition to three drop tanks. See also References External links RAF Eurofighter page Category:1994 establishments in Europe Variants Typhoon F2 |
Pelargonium is a genus of flowering plants which includes about 200 species of perennials, succulents, and shrubs, commonly known as geraniums, pelargoniums, or storksbills. Confusingly, Geranium is the botanical name and common name of a separate genus of related plants (also known as cranesbills). Both genera belong to the family Geraniaceae. Linnaeus originally included all the species in one genus, Geranium, and they were later separated into two genera by Charles L’Héritier in 1789. Pelargonium species are evergreen perennials indigenous to temperate and tropical regions of the world, with many species in southern Africa. They are drought and heat tolerant, but can tolerate only minor frosts. |
Some species are extremely popular garden plants, grown as houseplants and bedding plants in temperate regions.They have a long flowering period, with flowers mostly in purple, red and orange, or white. Etymology The name Pelargonium is derived from the Greek πελαργός, pelargós (stork), because the seed head looks like a stork's beak. Dillenius originally suggested the name 'stork', because Geranium was named after a crane — "a πελαργός, ciconia, sicuti vocamus Gerania, γερανός, grus" (as pelargos, stork, as we call the Gerania, geranos, crane). Despite the Latin, this should not be confused with the modern-day genus Ciconia, of birds in the stork family. |
Description Pelargonium occurs in a large number of growth forms, including herbaceous annuals, shrubs, subshrubs, stem succulents and geophytes. The erect stems bear five-petaled flowers in umbel-like clusters, which are occasionally branched. Because not all flowers appear simultaneously but open from the centre outwards, this is a form of inflorescence is referred to as pseudoumbels. The flower has a single symmetry plane (zygomorphic), which distinguishes it from the Geranium flower, which has radial symmetry (actinomorphic). Thus the lower three (anterior) petals are differentiated from the upper two (posterior) petals. The posterior sepal is fused with the pedicel to form a hypanthium (nectary tube). |
The nectary tube varies from only a few millimeters, up to several centimeters, and is an important floral characteristic in morphological classification. Stamens vary from 2 to 7, and their number, position relative to staminodes, and curvature are used to identify individual species. There are five stigmata in the style. For the considerable diversity in flower morphology, see figure 1 of Röschenbleck et al. (2014) Leaves are usually alternate, and palmately lobed or pinnate, often on long stalks, and sometimes with light or dark patterns. The leaves of Pelargonium peltatum (Ivy-leaved Geranium), have a thick cuticle better adapting them for drought tolerance. |
Taxonomy Pelargonium is the second largest genus (after Geranium) within the family Geraniaceae, within which it is sister to the remaining genera of the family in its strict sense, Erodium, Geranium, and Monsonia including Sarcocaulon. The Geraniaceae have a number of genetic features unique amongst angiosperms, including highly rearranged plastid genomes differing in gene content, order and expansion of the inverted repeat. Genus history The name Pelargonium was first proposed by Dillenius in 1732, who described and illustrated seven species of geraniums from South Africa that are now classified as Pelargonium. |
Dillenius, who referred to these seven species with apparent unique characteristics as Geranium Africanum (African Geranium) suggested "Possent ergo ii, quibus novi generis cupido est, ea, quorum flores inaequales vel et irrregulares sunt, Pelargonia vocare" (It would be possible therefore, if anyone wishes to make a new genus [of these geraniums] of which the flowers are unequal or irregular, to call them Pelargonia).The name was then formally introduced by Johannes Burman in 1738. However Carl Linnaeus who first formally described these plants in 1753 did not recognise Pelargonium and grouped together in the same genus (Geranium) the three similar genera Erodium, Geranium, and Pelargonium. |
Linnaeus' reputation prevented further differentiation for forty years. The eventual distinction between them was made by Charles L’Héritier based on the number of stamens or anthers, seven in the case of Pelargonium. In 1774, P. cordatum, P. crispum, P. quercifolium and P. radula were introduced, followed by P. capitatum in 1790. Circumscription Pelargonium is distinguished from the other genera in the family Geraniaceae by the presence of a hypanthium, which consists of an adnate nectar spur with one nectary, as well as a generally zygomorphic floral symmetry. Subdivision De Candolle first proposed dividing the genus into 12 sections in 1824, based on the diversity of growth forms. |
Traditionally the large number of Pelargonium species have been treated as sixteen sections, based on the classification of Knuth (1912) who described 15 sections, as modified by van der Walt et al. (1977-1997) who added Chorisma, Reniformia and Subsucculentia. These are as follows; section Campylia (Lindley ex Sweet) de Candolle section Chorisma (Lindley ex Sweet) de Candolle section Ciconium (Sweet) Harvey section Cortusina (DC.) Harvey section Glaucophyllum Harvey section Hoarea (Sweet) de Candolle section Isopetalum (Sweet) de Candolle section Jenkinsonia (Sweet) de Candolle section Ligularia (Sweet) Harvey section Myrrhidium de Candolle section Otidia (Lindley ex Sweet) de Candolle section Pelargonium (Sweet) Harvey section Peristera de Candolle section Polyactium de Candolle section Reniformia (Knuth) Dreyer section Subsucculentia J.J.A. |
van der Walt Phylogenetic analyses All subdivision classifications had depended primarily on morphological differences till the era of phylogenetic analyses (Price and Palmer 1993). However phylogenetic analysis shows only three distinct clades, labelled A, B and C. In this analysis not all sections were monophyletic although some were strongly supported including Chorisma, Myrrhidium and Jenkinsonia, while other sections were more paraphyletic. This in turn has led to a proposal, informal at this stage of a reformulation of the infrageneric subdivision of Pelargonium. In the proposed scheme of Weng et al. there would be two subgenera, based on clades A+B, and C respectively and seven sections based on subclades. |
Subsequent analysis with an expanded taxa set confirmed this infrageneric subdivision into two groups which also correspond to chromosome length (<1.5 μ, 1.5-3.0μ), but also two subclades within each major clade, suggesting the presence of four subgenera, these correspond to clades A, B, C1 and C2 of the earlier analysis, A being by far the largest clade with 141 taxa. As before the internal structure of the clades supported monophyly of some sections (Myrrhidium, Chorisma, Reniformia, Pelargonium, Ligularia and Hoarea) but paraphyly in others (Jenkinsonia, Ciconium, Peristera). A distinct clade could be identified within the paraphyletic Polyactium, designated section Magnistipulacea. |
As a result, Polyactium has been split up to provide this new section, which in itself contains two subsections, Magnistipulacea and Schizopetala, following Knuth's original treatment of Polyactium as having four subsections. Thus Röschenbleck et al. (2014) provide a complete revision of the subgeneric classification of Pelargonium based on four subgenera corresponding to their major clades (A, B, C1, C2); subgenus Magnipetala Roeschenbl. & F. Albers Type: Pelargonium praemorsum (Andrews) F Dietrich subgenus Parvulipetala Roeschenbl. & F. Albers Type: Pelargonium hypoleucum Turczaninow subgenus Paucisignata Roeschenbl. & F. Albers Type: Pelargonium zonale (L.) L'Hér. in Aiton subgenus Pelargonium L'Hér. |
Type: Pelargonium cucullatum (L.) W. Aiton Sixteen sections were then assigned to the new subgenera as follows, although many species remained only assigned to subgenera at this stage subgenus Magnipetala 3 sections section Chorisma (Lindley ex Sweet) de Candolle - 4 species section Jenkinsonia (Sweet) de Candolle - 11 species section Myrrhidium de Candolle - 8 species subgenus Parvulipetala 3 sections section Isopetalum (Sweet) de Candolle - 1 species (Pelargonium cotyledonis (L.) L'Hér.) section Peristera de Candolle - 30 species section Reniformia (Knuth) Dreyer - 8 species subgenus Paucisignata 2 sections section Ciconium (Sweet) Harvey - 16 species section Subsucculentia J.J.A. |
van der Walt - 3 species subgenus Pelargonium 8 sections section Campylia (Lindley ex Sweet) de Candolle - 9 species section Cortusina (DC.) Harvey - 7 species section Hoarea (Sweet) de Candolle - 72 species section Ligularia (Sweet) Harvey - 10 species section Magnistipulacea Roeschenbl. & F. Albers Type: Pelargonium schlecteri Knuth - 2 subsections subsection Magnistipulacea Roeschenbl. & F. Albers Type: Pelargonium schlecteri Knuth - 2 species (P. schlecteri & P. luridum) subsection Schizopetala (Knuth) Roeschenbl. & F. Albers Type: Pelargonium caffrum (Eckl. & Zeyh.) Steudel - 3 species (P. caffrum, P. bowkeri, P. schizopetalum) section Otidia (Lindley ex Sweet) de Candolle - 14 species section Pelargonium L'Hér. |
- 34 species section Polyactium de Candolle - 2 subsections subsection Caulescentia Knuth - 1 species (Pelargonium gibbosum) subsection Polyactium de Candolle - 7 species Subgenera Subgenus Magnipetala: Corresponds to clade C1, with 24 species. Perennial to short lived, spreading subshrubs, rarely herbaceous annuals. Petals five, but may be four, colour mainly white. Mainly winter rainfall region of South Africa, spreading into summer rainfall region. One species in northern Namibia and Botswana. Two species in East Africa and Ethiopia. Chromosomes x=11 and 9. Subgenus Parvulipetala: Corresponds to clade B, with 39-42 species. Perennials, partly annuals. Petals five and equal, colour white or pink to deep purplish red. |
Mainly South Africa, but also other southern hemisphere except South America. a few species in East Africa and Ethiopia. Chromosomes x=7-19. Subgenus Paucisignata: Corresponds to clade C2, with 25-27 species. Erect sometimes trailing shrubs or subshrubs, rarely geophytes or semi-geophytes. Petals five and equal, colour pink to red sometimes white. Summer rainfall region of South Africa, spreading into winter rainfall region and northern Namibia, with a few species in tropical Africa, Ethiopia, Somalia, Madagascar, the Arabian Peninsula and Asia Minor. Chromosomes x=mainly 9 or 10, but from 4-18. Subgenus Pelargonium: Corresponds to clade A, with 167 species. Frequently xerophytic deciduous perennials with many geophytes and succulent subshrubs, less frequently woody evergreen shrubs or annual herbs. |
Petals five, colour shades of pink to purple or yellow. Winter rainfall region of South Africa and adjacent Namibia, spreading to summer rainfall area, and two species in tropical Africa. Chromosomes x=11, may be 8-10. Species Pelargonium has between 200 and 280 species. The Plant List currently accepts 250 species names. Röschenbleck et al lists 281 taxa. There is considerable confusion as to which Pelargonium are true species, and which are cultivars or hybrids. The nomenclature has changed considerably since the first plants were introduced to Europe in the 17th century. Distribution Pelargonium is a large genus within the family Geraniaceae, which has a worldwide distribution in temperate to subtropical zones with some 800 mostly herbaceous species. |
Pelargonium itself is native to southern Africa (including Namibia) and Australia. Southern Africa contains 90% of the genus, with only about 30 species found elsewhere, predominantly the East African rift valley (about 20 species) and southern Australia, including Tasmania. The remaining few species are found in southern Madagascar, Yemen, Iraq, Asia Minor, the north of New Zealand and isolated islands in the south Atlantic Ocean (Saint Helena and Tristan da Cunha) and Socotra in the Indian Ocean. The centre of diversity is in southwestern South Africa where rainfall is confined to the winter, unlike the rest of the country where rainfall is predominantly in the summer months. |
Most of the Pelargonium plants cultivated in Europe and North America have their origins in South Africa. Ecology Pelargonium species are eaten by the caterpillars of some Lepidoptera species, including the noctuid moth angle shades, Phlogophora meticulosa. The diurnal butterflies Cacyreus marshalli and C. tespis (Lycaenidae), native to southern Africa, also feed on Geranium and Pelargonium. C. marshallii has been introduced to Europe and can develop into a pest on cultivated Pelargoniums. It has naturalised along the Mediterranean, but does not survive the winter in Westen Europe. The Japanese beetle, an important agricultural insect pest, becomes rapidly paralyzed after consuming flower petals of the garden hybrids known as "zonal geraniums" (P. × hortorum). |
The phenomenon was first described in 1920, and subsequently confirmed. Research conducted by Dr. Christopher Ranger with the USDA Agricultural Research Service and other collaborating scientists have demonstrated the excitatory amino acid called quisqualic acid present within the flower petals is responsible for causing paralysis of the Japanese beetle. Quisqualic acid is thought to mimic L-glutamic acid, which is a neurotransmitter in the insect neuromuscular junction and mammalian central nervous system. A study by the Laboratory of Apiculture & Social Insects group at the University of Sussex on the attractiveness of common garden plants to pollinators found that a cultivar of Pelargonium × hortorum was unattractive to pollinators in comparison to other selected garden plants such as Lavandula (lavender) and Origanum. |
Pests and diseases The geranium bronze butterfly is a pest of Pelargonium species. The larvae of the geranium bronze bore into the stem of the host plant, causing the stem to typically turn black and die soon after. Geranium bronze are currently listed as an A2 quarantine pest by the European and Mediterranean Plant Protection Organization and can cause significant damage to Pelargonium species. Cultivation Various types of Pelargonium are regular participants in flower shows and competitive events, with numerous societies devoted exclusively to their cultivation. They are easy to propagate vegetatively from cuttings. Zonal geraniums grow in U.S. Department of Agriculture hardiness zones 9 through 12. |
Zonal geraniums are basically tropical perennials. Although they are often grown as annuals, they may overwinter in zones as cool as zone 7. Cultivation history The first species of Pelargonium known to be cultivated was P. triste, a native of South Africa. It was probably brought to the Botanical Garden in Leiden before 1600 on ships which had stopped at the Cape of Good Hope. In 1631, the English gardener John Tradescant the elder bought seeds from Rene Morin in Paris and introduced the plant to England. By 1724, P. inquinans, P. odoratissimum, P. peltatum, P. vitifolium, and P. zonale had been introduced to Europe. |
Cultivars There was little attempt at any rational grouping of Pelargonium cultivars, the growing of which was revived in the mid-twentieth century, and the origins of many if not most were lost in obscurity. In 1916 the American botanist Liberty Hyde Bailey (1858–1954) introduced two new terms for zonal and regal pelargoniums. Those pelargoniums which were largely derived from P. zonale he referred to as P. × hortorum (i.e. from the garden), while those from P. cucullatum he named P. × domesticum (i.e. from the home). In the late 1950s a list (the Spalding List) was produced in the United States, based on nursery listings and the 1897 list of Henri Dauthenay. |
It described seven groups, listing each cultivar with the list of its originator, and in most cases a date. These were Species, Zonals, Variegated-Leaved, Domesticum (Regals), Ivy-Leaved, Scented-Leaved and Old. In the 1970s the British Pelargonium and Geranium Society produced a checklist and the Australian Geranium Society started to produce a register but it was not completed till its author, Jean Llewellyn's death in 1999. None of these were published. The most complete list in its time was the 2001 compilation by The Geraniaceae Group, which included all cultivars up to 1959. Registration of cultivars is the responsibility of the Pelargonium & Geranium Society (PAGS: formed in 2009 from the British Pelargonium and Geranium Society and the British and European Geranium Society) which administers the International Register of Pelargonium Cultivars. |
PAGS is the International Cultivar Registration Authority (ICRA) of the International Society for Horticultural Science for pelargoniums. Cultivated pelargoniums are commonly divided into six groups in addition to species pelargoniums and primary hybrids. The following list is ordered by position in the PAGS classification. Abbreviations indicate Royal Horticultural Society usage. A. Zonal (Z) B. Ivy-leaved (I) C. Regal (R) D. Angel (A) E. Unique (U) F. Scented-leaved (Sc) G. Species H. Primary hybrids Of these, A, U and Sc groups are sometimes lumped together as Species Derived (Sppd). This term implies that they are closely related to a species from which they were derived, and do not fit into the R, I or Z groups. |
In addition to the primary groups, additional descriptors are used. The Royal Horticultural Society has created description codes. These include; Cactus (Ca) Coloured foliage (C) Decorative (Dec) Double (d) Dwarf (Dw) Dwarf Ivy-leaved (Dwl) Frutetorum (Fr) Miniature (Min) Miniature Ivy-leaved (MinI) Stellar (St) Tulip (T) Variegated (v) These may then be combined to form the code, e.g. Pelargonium 'Chelsea Gem' (Z/d/v), indicating Zonal Double with variegated foliage. Crosses between groups are indicated with an ×, e.g. Pelargonium 'Hindoo' (R × U), indicating a Regal × Unique cross. A. Zonal pelargoniums (Pelargonium × hortorum Bailey) These are known as zonal geraniums because many have zones or patterns in the center of the leaves, this is the contribution of the Pelargonium zonale parent. |
Common names include storksbill, fish or horseshoe geraniums. They are also referred to as Pelargonium × hortorum Bailey. Zonal pelargoniums are tetraploid, mostly derived from P. inquinans and P. zonale, together with P. scandens and P. frutetorum. Zonal pelargoniums are mostly bush-type plants with succulent stems grown for the beauty of their flowers, traditionally red, salmon, violet, white or pink. The scarlet colouring is attributed to the contribution of P. inquinans. Flowers may be double or single. They are the pelargoniums most often confused with genus Geranium, particularly in summer bedding arrangements. This incorrect nomenclature is widely used in horticulture, particularly in North America. |
Zonals include a variety of plant types along with genetic hybrids such as hybrid ivy-leaved varieties that display little or no ivy leaf characteristics (the Deacons varieties), or the Stellar varieties. Hybrid zonals are crosses between zonals and either a species or species-derived pelargonium. There are hundreds of zonal cultivars available for sale, and like other cultivars are sold in series such as 'Rocky Mountain', each of which is named after its predominant colour, e.g. 'Rocky Mountain Orange', 'White', 'Dark Red', etc. (i) Basic plants – Mature plants with foliage normally exceeding 7 " (180 mm) in height above the rim of the pot. |
For exhibition these should be grown in a pot exceeding 4¾ " (120 mm) in diameter but not normally exceeding 6½ " (165 mm). (ii) Dwarf plants – Smaller than basic. Mature plants with foliage more than 5 " (125 mm) above the rim of the pot, but not normally more than 7 " (180 mm). For exhibition should be grown in a pot exceeding 3½ " (90 mm) but not exceeding 4¾ " (120 mm). They should not exceed 200 mm in height, grown in an 11 cm pot. (iii) Miniature plants – Slowly growing pelargoniums. Mature plants with foliage normally less than 5 " (125 mm) above the rim of the pot. |
For exhibition should be grown in a pot not exceeding 3½ " (90 mm). They should not exceed 125 mm in height, grown in a 9 cm pot. (iv) Micro-miniature plants – Smaller and more slowly growing than miniature pelargoniums. Mature plants with foliage normally less than 4 " (100 mm) above the rim of the pot. They should not exceed 75 cm in height, grown in a 6 cm pot. Usually no separate classes for these in exhibition and will therefore normally be shown as Miniature Zonals. (v) Deacon varieties –Genetic hybrid similar to a large Dwarf. For exhibition (when shown in a separate class), usually grown in a pot not exceeding 5 " (125 mm), otherwise as for Dwarf Zonals. |
(vi) Stellar varieties – A relatively modern genetic hybrid originating from the work done by the Australian hybridiser Ted Both in the late 1950s and 1960s from crosses between Australian species and Zonal types. Easily identifiable by their distinctive half-star-shaped leaves and slim-petalled blooms which create an impression of being star shaped (or five fingered). Single varieties tend to have larger elongated triangular petals whereas doubles tend to have thin feathered petals that are tightly packed together. For exhibition purposes there is a separate class for 'Stellar' varieties, but being Zonals could be shown in an open class for Basic, Dwarf or Miniature Zonals (unless otherwise stated). |
Also known as "The Five-fingered Geraniums", "Staphysagroides", "Both’s Staphs", "Both’s Hybrid Staphs", "Fingered Flowers" and "Bodey’s Formosum Hybrids". Fancy-leaf zonal pelargoniums – besides having green leaves with or without zoning, this group also have variable coloured foliage that is sometimes used in classifying for exhibition purposes, e.g. ‘Bicolour’, ‘Tricolour’, ‘Bronze’ or ‘Gold’. Other foliage types are: ‘Black’ or ‘Butterfly’. There are an increasing number of these plants with showy blooms; (a) Bicolour – includes those with white or cream veined leaves or those with two distinct colours with clearly defined edges, other than the basic zone. (b) Tricolour – (May be Silver Tricolour (usually called a Silver Leaf) or a Gold Tricolour). |
(i) Gold Tricolour – Leaves of many colours including red and gold, but usually with clearly defined edges of golden yellow and having a leaf zone, usually red or bronze, that overlays two or more of the other distinct leaf colours, so that the zone itself appears as two or more distinct colours. (ii) Silver Tricolour or Silver Leaf – These tend to resemble a normal bi-colour leaf plant with two distinct colours usually of green and pale cream or white; the third colour is usually made up of bronze zoning. When this zoning overlays the green part of the leaf it is deemed to represent a silver colour. |
Subsets and Splits