Google Assistant is an artificial intelligence-powered virtual assistant developed by Google, available on mobile and smart home devices. Unlike the company's previous virtual assistant, Google Now, Google Assistant can engage in two-way conversations. Assistant debuted in May 2016 as part of Google's messaging app Allo, its voice-activated speaker Google Home. After a period of exclusivity on the Pixel and Pixel XL smartphones, it began to be deployed on other Android devices in February 2017, including third-party smartphones and Android Wear, was released as a standalone app on the iOS operating system in May 2017. Alongside the announcement of a software development kit in April 2017, the Assistant has been, is being, further extended to support a large variety of devices, including cars and third party smart home appliances; the functionality of the Assistant can be enhanced by third-party developers. In 2017, Google Assistant was installed on more than 400 million devices. Users interact with Google Assistant through natural voice, though keyboard input is supported.
In the same nature and manner as Google Now, the Assistant is able to search the Internet, schedule events and alarms, adjust hardware settings on the user's device, show information from the user's Google account. Google has announced that the Assistant will be able to identify objects and gather visual information through the device's camera, support purchasing products and sending money, as well as identifying songs. At CES 2018, the first Assistant-powered smart displays were announced, with the first one being released in July 2018. Google Assistant was unveiled during Google's developer conference on May 18, 2016, as part of the unveiling of the Google Home smart speaker and new messaging app Allo; that month, Google assigned Google Doodle leader Ryan Germick and hired former Pixar animator Emma Coats to develop "a little more of a personality." For system-level integration outside of the Allo app and Google Home, Google Assistant was exclusive to the Pixel and Pixel XL smartphones. In February 2017, Google announced that it had begun to enable access to the Assistant on Android smartphones running Android Marshmallow or Nougat, beginning in select English-speaking markets.
Android tablets did not receive the Assistant as part of this rollout. The Assistant is integrated in Android Wear 2.0, will be included in future versions of Android TV and Android Auto. In October 2017, the Google Pixelbook became the first laptop to include Google Assistant. Google Assistant came to the Google Pixel Buds. In December 2017, Google announced that the Assistant would be released for phones running Android Lollipop through an update to Google Play Services, as well as tablets running 6.0 Marshmallow and 7.0 Nougat. On May 15, 2017, Android Police reported that Google Assistant would be coming to the iOS operating system as a separate app; the information was confirmed two days at Google's developer conference. In January 2018 at the Consumer Electronics Show, the first Assistant-powered "smart displays" were released. Smart displays were shown at the event from Lenovo, Sony, JBL and LG; these devices have support for Google Duo video calls, YouTube videos, Google Maps directions, a Google Calendar agenda, viewing of smart camera footage, in addition to services which work with Google Home devices.
These devices are based on Google-developed software. Google unveiled its own smart display, Google Home Hub, in October 2018, which utilizes a different system platform. In December 2016, Google launched "Actions on Google", a developer platform for Google Assistant. Actions on Google allows 3rd party developers to build apps for Google Assistant. In March 2017, Google added new tools for developing on Actions on Google to support the creation of games for Google Assistant. Limited to the Google Home smart speaker, Actions on Google was made available to Android and iOS devices in May 2017, at which time Google introduced an app directory for overview of compatible products and services. To incentivize developers to build Actions, Google announced a competition, in which first place won tickets to Google's 2018 developer conference, $10,000, a walk-through of Google's campus, while second place and third place received $7,500 and $5,000 and a Google Home. In April 2017, a software development kit was released, allowing third-party developers to build their own hardware that can run Google Assistant.
It has been integrated into Raspberry Pi, cars from Audi and Volvo, smart home appliances, including fridges and ovens, from companies including iRobot, LG, General Electric, D-Link. Google updated the SDK in December 2017 to add several features that only the Google Home smart speakers and Google Assistant smartphone apps had supported; the features include: letting third-party device makers incorporate their own "Actions on Google" commands for their respective products incorporating text-based interactions and more languages allowing users to set a precise geographic location for the device to enable improved location-specific queries. On May 2, 2018, Google announced a new program on their blog that focuses on investing in the future of Google Assistant through early-stage startups, their focus was to build an environment where developers could build richer experiences for their users. This includes startups that broaden Assistant's features, are building new hardware devices, or differentiating in different industries.
A duplex communication system is a point-to-point system composed of two or more connected parties or devices that can communicate with one another in both directions. Duplex systems are employed in many communications networks, either to allow for simultaneous communication in both directions between two connected parties or to provide a reverse path for the monitoring and remote adjustment of equipment in the field. There are two types of duplex communication systems: half-duplex. In a full-duplex system, both parties can communicate with each other simultaneously. An example of a full-duplex device is a telephone; the earphone reproduces the speech of the remote party as the microphone transmits the speech of the local party, because there is a two-way communication channel between them, or more speaking, because there are two communication channels between them. In a half-duplex system, both parties can communicate with each other, but not simultaneously. An example of a half-duplex device is a walkie-talkie two-way radio that has a "push-to-talk" button.
To listen to the other person they release the button, which turns on the receiver but turns off the transmitter. Systems that do not need the duplex capability may instead use simplex communication, in which one device transmits and the others can only "listen". Examples are broadcast radio and television, garage door openers, baby monitors, wireless microphones, surveillance cameras. In these devices the communication is only in one direction. A half-duplex system provides communication in both directions, but only one direction at a time. Once a party begins receiving a signal, it must wait for the transmitter to stop transmitting, before replying. An example of a half-duplex system is a two-party system such as a walkie-talkie, wherein one must use "over" or another designated keyword to indicate the end of transmission, ensure that only one party transmits at a time, because both parties transmit and receive on the same frequency. A good analogy for a half-duplex system would be a one-lane road with traffic controllers at each end, such as a two-lane bridge under re-construction.
Traffic can flow in both directions, but only one direction at a time, regulated by the traffic controllers. Half-duplex systems are used to conserve bandwidth, since only a single communication channel is needed, shared alternately between the two directions. For example, a walkie-talkie requires only a single frequency for bidirectional communication, while a cell phone, a full-duplex device, requires two frequencies to carry the two simultaneous voice channels, one in each direction. In automatically run communications systems, such as two-way data-links, the time allocations for communications in a half-duplex system can be controlled by the hardware. Thus, there is no waste of the channel for switching. For example, station A on one end of the data link could be allowed to transmit for one second station B on the other end could be allowed to transmit for one second, the cycle repeats. In half-duplex systems, if more than one party transmits at the same time, a collision occurs, resulting in lost messages.
A full-duplex system, or sometimes called double-duplex, allows communication in both directions, unlike half-duplex, allows this to happen simultaneously. Land-line telephone networks are full-duplex, since they allow both callers to speak and be heard at the same time, with the transition from four to two wires being achieved by a hybrid coil in a telephone hybrid. Modern cell phones are full-duplex. A good analogy for a full-duplex system is a two-lane road with one lane for each direction. Moreover, in most full-duplex mode systems carrying computer data, transmitted data does not appear to be sent until it has been received and an acknowledgment is sent back by the other party. In this way, such systems implement reliable transmission methods. Two-way radios can be designed as full-duplex systems, transmitting on one frequency and receiving on another. Frequency-division duplex systems can extend their range by using sets of simple repeater stations because the communications transmitted on any single frequency always travel in the same direction.
Full-duplex Ethernet connections work by making simultaneous use of two physical twisted pairs inside the same jacket, which are directly connected to each networked device: one pair is for receiving packets, while the other pair is for sending packets. This makes the cable itself a collision-free environment and doubles the maximum total transmission capacity supported by each Ethernet connection. Full-duplex has several benefits over the use of half-duplex. First, there are no collisions. Second, full transmission capacity is available in both directions because the send and receive functions are separate. Third, since there is only one transmitter on each twisted pair, stations do not need to wait for others to complete their transmissions; some computer-based systems of the 1960s and 1970s required full-duplex facilities for half-duplex operation, since their poll-and-response schemes could not tolerate the slight delays in reversing the direction of transmission in a half-duplex line. Where channel access methods are used in point-to-multipoint networks (such as cellular networks
Duplex is a 2003 American black comedy film directed and narrated by Danny DeVito, starring Ben Stiller and Drew Barrymore. The film was called Our House for its release in Ireland. Alex Rose and Nancy Kendricks are a young, married New York couple in search of their dream home; when they find the perfect Brooklyn brownstone, they are giddy with anticipation. The duplex is a dream come true, complete with multiple fireplaces, except for one thing: Mrs. Connelly, the old lady who lives on the rent-controlled top floor. Assuming she is elderly and ill, they take the apartment. However, they soon realize that Mrs. Connelly is in fact an energetic senior who enjoys watching her television at top volume day and night and rehearsing in a brass band; as a writer, Alex is attempting to finish his novel against a looming deadline. However, he is interrupted daily by Mrs. Connelly's numerous demands and requests, what begins as a nuisance escalates into an all-out war. Alex and Nancy try to get Mrs. Connelly to move out.
Next, they try to file a noise complaint against her, but discover that she has gone to the police first and filed a harassing complaint against them. Mrs. Connelly soon turns all of Alex and Nancy's friends against them by play-acting as the "poor, old lady" and makes it appear that the young couple are out to harm her; when Nancy loses her job and Alex misses his deadline the pair are trapped at home together with Mrs. Connelly with no place to go, their rage turns to homicidal fantasy as they plot ways to get rid of their manipulative, no-good neighbor. After peace overtures and a break-in lead to nothing and Nancy decide to hire a hitman, named Chick, to kill her. However, his asking price for doing the hit is $25,000. Unable to come up with the money, Alex approaches his friend and fellow writer, Coop, to ask for a loan, but is rudely rebuffed. Desperate and needing the money in two days, they sell every possession they own to pay Chick who will do the hit on Christmas Eve. Chick does break into Mrs. Connelly's apartment as planned, but fails to kill her when she defends herself with her speargun by shooting him in the shoulder, forcing him to flee, the couple in fact have to rescue the old woman when the struggle results in a fire in her apartment.
Accepting defeat and Nancy decide to evict themselves, but find out that the old woman has died right when they leave. Alex and Nancy, now with no jobs, friends, or money left, move away where they contemplate their strange encounters, but here the audience learns in a climatic plot twist that the realtor of the duplex and the ill-tempered NYPD Officer Dan who had harassed and distrusted the couple and always sided with Mrs. Connelly in her arguments with Alex and Nancy, Mrs. Connelly herself have been doing this to others; this wicked and unethical trio have been running a mean-spirited, real-estate scam for several years: Kenneth sells the ground floor apartment only to good-natured and harmless young couples. Mrs. Connelly, aided by the corrupt Officer Dan and destroys the young couple's lives forcing them to move out. Mrs. Connelly fakes her own death so that the couple will never return seeking revenge... and leaving Mrs. Connelly and Dan to collect and live off of the sales commission from the next unsuspecting occupants that buy the ground floor apartment as part of a never-ending vicious cycle.
Alex and Nancy were her son's latest victims among so many. At the conclusion, it is revealed in a voice-over by Alex. Like all of the other couples that the trio scammed, they never saw Mrs. Connelly or returned to Brooklyn again. While Mrs. Connelly and Officer Dan continue their scam by targeting the next friendly young couple that moves into the ground-floor apartment right after Alex and Nancy move out, Alex used his unpleasant experience of living there as inspiration for writing his next book, titled "Duplex", which became a best-selling novel, saving Alex and Nancy from their life of poverty, giving the film a semi-happy ending. Ben Stiller as Alex Rose Drew Barrymore as Nancy Kendricks Eileen Essell as Mrs. Connelly Harvey Fierstein as Kenneth Justin Theroux as Coop James Remar as Chick Robert Wisdom as Officer Dan Swoosie Kurtz as Jean Wallace Shawn as Herman Maya Rudolph as Tara Amber Valletta as Celine Michelle Krusiec as Dr. Kang Tracey Walter as Pharmacy Customer Danny DeVito as Narrator The film has a 50/100 on Metacritic and a 35% approval rating on Rotten Tomatoes.
Roger Ebert of the Chicago Sun-Times gave the film two stars out of four and wrote that the "murder schemes aimed at Mrs. Connelly don't generate the laughter they should, maybe because no matter what she does, she still seems, unredeemably, a sweet little old lady.'Duplex' is all about plotting. We can't identify with Mrs. Connelly, that's for sure, but we can't identify with Alex and Nancy, because we don't share their frustration -- and the reason we don't is because we don't believe it. There's too much contrivance and not enough plausibility, so we're just enjoying the performances and wishing they'd been in a more persuasive movie."Barrymore earned a Golden Raspberry Award nomination for Worst Actress for her performances in both Duplex and Charlie's Angels: Full Throttle, but lost to Jennifer Lopez for Gigli. On a US $40 million budget, it grossed $9,692,13
Nucleic acid double helix
In molecular biology, the term double helix refers to the structure formed by double-stranded molecules of nucleic acids such as DNA. The double helical structure of a nucleic acid complex arises as a consequence of its secondary structure, is a fundamental component in determining its tertiary structure; the term entered popular culture with the publication in 1968 of The Double Helix: A Personal Account of the Discovery of the Structure of DNA, by James Watson. The DNA double helix biopolymer of nucleic acid, held together by nucleotides which base pair together. In B-DNA, the most common double helical structure found in nature, the double helix is right-handed with about 10–10.5 base pairs per turn. The double helix structure of DNA contains a major minor groove. In B-DNA the major groove is wider than the minor groove. Given the difference in widths of the major groove and minor groove, many proteins which bind to B-DNA do so through the wider major groove; the double-helix model of DNA structure was first published in the journal Nature by James Watson and Francis Crick in 1953, based upon the crucial X-ray diffraction image of DNA labeled as "Photo 51", from Rosalind Franklin in 1952, followed by her more clarified DNA image with Raymond Gosling, Maurice Wilkins, Alexander Stokes, Herbert Wilson, base-pairing chemical and biochemical information by Erwin Chargaff.
The prior model was triple-stranded DNA. The realization that the structure of DNA is that of a double-helix elucidated the mechanism of base pairing by which genetic information is stored and copied in living organisms and is considered one of the most important scientific discoveries of the 20th century. Crick and Watson each received one third of the 1962 Nobel Prize in Physiology or Medicine for their contributions to the discovery. Hybridization is the process of complementary base pairs binding to form a double helix. Melting is the process by which the interactions between the strands of the double helix are broken, separating the two nucleic acid strands; these bonds are weak separated by gentle heating, enzymes, or mechanical force. Melting occurs preferentially at certain points in the nucleic acid. T and A rich regions are more melted than C and G rich regions; some base steps are susceptible to DNA melting, such as T A and T G. These mechanical features are reflected by the use of sequences such as TATA at the start of many genes to assist RNA polymerase in melting the DNA for transcription.
Strand separation by gentle heating, as used in polymerase chain reaction, is simple, providing the molecules have fewer than about 10,000 base pairs. The intertwining of the DNA strands makes long segments difficult to separate; the cell avoids this problem by allowing its DNA-melting enzymes to work concurrently with topoisomerases, which can chemically cleave the phosphate backbone of one of the strands so that it can swivel around the other. Helicases unwind the strands to facilitate the advance of sequence-reading enzymes such as DNA polymerase; the geometry of a base, or base pair step can be characterized by 6 coordinates: shift, rise, tilt and twist. These values define the location and orientation in space of every base or base pair in a nucleic acid molecule relative to its predecessor along the axis of the helix. Together, they characterize the helical structure of the molecule. In regions of DNA or RNA where the normal structure is disrupted, the change in these values can be used to describe such disruption.
For each base pair, considered relative to its predecessor, there are the following base pair geometries to consider: Shear Stretch Stagger Buckle Propeller: rotation of one base with respect to the other in the same base pair. Opening Shift: displacement along an axis in the base-pair plane perpendicular to the first, directed from the minor to the major groove. Slide: displacement along an axis in the plane of the base pair directed from one strand to the other. Rise: displacement along the helix axis. Tilt: rotation around the shift axis. Roll: rotation around the slide axis. Twist: rotation around the rise axis. X-displacement y-displacement inclination tip pitch: the number of base pairs per complete turn of the helix. Rise and twist determine the pitch of the helix; the other coordinates, by contrast, can be zero. Slide and shift are small in B-DNA, but are substantial in A- and Z-DNA. Roll and tilt make successive base pairs less parallel, are small. Note that "tilt" has been used differently in the scientific literature, referring to the deviation of the first, inter-strand base-pair axis from perpendicularity to the helix axis.
This corresponds to slide between a succession of base pairs, in helix-based coordinates is properly termed "inclination". At least three DNA conformations are believed to be found in nature, A-DNA, B-DNA, Z-DNA; the B form described by James Watson and Francis Crick is believed to predominate in cells. It extends 34 Å per 10 bp of sequence; the double helix makes one complete turn about its axis every 10.4–10.5 base pairs in solution. This frequency of twist depends on stacking forces that each base exerts on its neighbours in the chain; the absolute configuration of the bases determines the direction of the helical curve for a given conformation. A-DNA and Z-DNA differ in their geometry and dimensions to B-DNA, although still form helical structures, it was long thought that the A form only occurs in dehydrated samples of
A duplex locomotive is a steam locomotive that divides the driving force on its wheels by using two pairs of cylinders rigidly mounted to a single locomotive frame. The concept was first used in France in 1863, but was developed in the early 1930s by the Baldwin Locomotive Works, the largest commercial builder of steam locomotives in North America, under the supervision of its chief engineer, Ralph P. Johnson. Prior to this, the term duplex locomotive was sometimes applied to articulated locomotives in general. While the side rods of a locomotive can be balanced by weights on the driving wheels since their motion is rotational, the reciprocating motions of the pistons, piston rods, main rods and valve gear cannot be balanced in this way. A two-cylinder locomotive has its two cranks "quartered" — set at 90° apart — so that the four power strokes of the double-acting pistons are evenly distributed around the cycle and there are no points at which both cylinders are at top or bottom dead center simultaneously.
A four-cylinder locomotive can be balanced in the longitudinal and vertical axes, although there are some rocking and twisting motions which can be dealt with in the locomotive's suspension and centering. Additional balance weight — "overbalance" — can be added to damp this, but at the cost of adding vertical forces, which are known technically as "dynamic augment" and colloquially as "hammer blow"; this can be damaging to the track, in extreme cases can cause the driving wheels to leave the track entirely. The heavier the reciprocating machinery, the greater these forces are, the greater a problem this becomes. In Europe this problem was overcome by dividing the drive between inside and outside cylinders, or else by using Articulated locomotives, although at the time it was not believed possible to run one stably at greater than 50 mph. American railroads proved to be unwilling to use locomotives with inside cylinders, so the problem of balance could not be solved by adding more cylinders per coupled wheel set.
As locomotives got larger and more powerful, their reciprocating machinery had to get stronger and thus heavier, thus the problems posed by imbalance and hammer blow became more severe. Speed played a factor, since the forces became greater and more destructive at higher wheel speeds. Ralph P. Johnson thought that the growing size and piston thrusts of existing express passenger locomotives could not be sustained with the by-then conventional 4-8-4 2-cylinder layout. In addition, he became convinced that a single pair of cylinders with conventional valve gear and piston valves was approaching the limits in terms of steam flow; the earliest attempt at duplex locomotive was an 0-6-6-0 tank locomotive designed by Jules Petiet in 1863 for the French Northern Railway, but the idea was not perpetuated. However, the innovation of more rigid hinges that permitted only horizontal swinging movements and not twisting or vertical movement was from ALCO, not seen until 1936's Union Pacific Challenger. Instead came the idea of having multiple groups of cylinders and driven wheels mounted in one rigid frame.
A "duplex" version of a 4-8-4 would be a 4-4-4-4, with the eight driving wheels split into two groups of four, each with its own set of cylinders and valve gear. The reciprocating mass of both sets would be less than the single set on the 4-8-4, since they would be under less stress and gentler piston thrusts; the cylinders have larger, more efficient valves. The most obvious tradeoff was that in Baldwin's proposed design, the rigid wheelbase was longer since the second set of cylinders had to be between the two sets of drivers; this was sufficiently concerning for many roads, for whom current locomotives were taxing enough, to reject the duplex idea. The first road to use the idea was the Baltimore and Ohio Railroad, who rejected a Baldwin proposal in 1932–33 but constructed the single Baltimore and Ohio Class N-1, #5600 George H. Emerson in the railroad's own shops without Baldwin's assistance; the locomotive was completed in May 1937 and managed to retain the same coupled wheelbase as the road's current 4-8-2s by having the second set of cylinders reversed, mounted alongside the firebox, driving the second set of coupled wheels forwards.
This proved to be less than ideal, the size of the cylinders and firebox both being constrained by this location, the long steam passages proving problematic, the cylinders suffering from the dust and heat of the nearby firebox. The locomotive was in light service and tested until withdrawal in 1943, it was not successful enough for the B&O to express any further interest. The next usage of the duplex type was the Pennsylvania Railroad's single S1, designed to meet a requirement to operate a 1,200 short tons train at 100 mph on level track and able to accelerate to that speed easily. In excess of 4,000 hp was necessary for that requirement, to meet it Baldwin and the PRR created the largest passenger steam locomotive built, a 6-4-4-6 locomotive 140 feet 2 1⁄2 inches long and weighing 1,060,000 lb with tender, it was, in fact, too large to work over the majority of the PRR's system and was placed into service only between Chicago and Crestline, Ohio. In service after December 1940, it proved powerful and capable but prone to wheelslip and surging, presaging the problems with duplex designs.
By and large, its flaws were written off as the teething troubles of an early, first-cut pr
A duplex house plan has two living units attached to each other, either next to each other via townhouses or above each other like apartments. By contrast, a building comprising two attached units on two distinct properties is considered semi-detached or twin homes but is called a duplex in parts of the Northeastern United States; the term "duplex" is not extended to three-unit and four-unit buildings, as they would be referred to with specific terms such as triplex and fourplex or quadplex/quadruplex. Because of the flexibility of the term, the line between an apartment building and a duplex is somewhat blurred, with apartment buildings tending to be bigger, while duplexes are the size of a normal house. British English usage refers to the number of levels within an apartment unit with duplex indicating two storeys and triplex for three. A semi-detached house would never be referred to as duplex in the United Kingdom; the word "duplex" is mispronounced with the last letter silent due to multiple misperceptions: that the English word came from French, that an English word naturalized from French needs to retain the French pronunciation, that the terminal -x would be silent in French.
But this English word came straight from educated English speakers' use of Latin, most English words that came from French words use naturalized pronunciation, the French pronunciation of the French cognate ends in /ɛks/ anyway. In dense areas like Manhattan and downtown Chicago, a duplex or duplex apartment refers to a maisonette, a single dwelling unit spread over two floors connected by an indoor staircase. A triplex apartment refers to an apartment spread out over three floors; these properties can be quite expensive and include the most expensive property in Manhattan as of 2006, a triplex atop The Pierre hotel. In this context, an apartment locating on one floor only may be called a simplex. In the United Kingdom, the term duplex is more used by property professionals such as architects and estate agents and refers only to a flat or apartment on two floors connected by an inner staircase though many newer apartments have open-plan designs including mezzanines; the traditional layout is called a maisonette, indicating a'house-like dwelling' raised above the ground or street.
In Australia, a duplex is considered a residential building containing two homes that share a common central wall. As such they are a mirror image of each other in layout. Referred to as a maisonette in South Australia. A paired home is two homes that have opposite side entries; the whole building is designed to look. Unlike a front to front duplex, the paired home helps provide more privacy for the homeowners. In urban planning, the term duplex is used more specifically. Major Canadian cities sometimes use the term duplex to refer to a building with one unit built above another. Edmonton defines'Duplex Housing' as "development consisting of a building containing only two Dwellings, with one Dwelling placed over the other in whole or in part with individual and separate access to each Dwelling". Calgary defines Duplex Dwelling as "a building which contains two Dwelling Units, one located above the other, with each having a separate entrance". Toronto proposes in their new Zoning Bylaw to define'Duplex Building' as a building that has only two dwelling units, one dwelling unit is or on top of the other dwelling unit.
Halifax defines Duplex Dwelling as "the whole of a dwelling, divided horizontally into two separate dwelling units, each of which has an independent entrance". Other major cities for dwelling units. Dallas defines the term duplex as "two dwelling units located on a lot". Philadelphia defines a duplex dwelling as "a dwelling occupied as the home or residence of two families, under one roof, each family occupying a single unit", a definition that excludes a pair of twin houses, two dwellings separated by a firewall that extends above the roofline. Other major cities do not use the term duplex in their land-use bylaws. San Francisco and Vancouver use the term Two-family dwelling. Winnipeg uses two-family; the definitions of these terms do not specify the physical relationship between the two dwelling units in the building. In cities such as Buffalo and Chicago the term Two-flat is used and defines it as a "residential building that contains 2 dwelling units located on a single lot; the dwelling units must share a common wall or common floor/ceiling."Where cities do not define the relationship of the dwelling units to one another, units may be built one on top of the other, or one beside the other.
The latter arrangement is more referred to as a semi-detached building
SNCF TGV Duplex
The TGV Duplex is a French high-speed train of the TGV family, manufactured by Alstom, operated by the French national railway company SNCF. It is unique among TGV trains; the Duplex inaugurated the third generation of TGV trainsets. It was specially designed to increase capacity on high-speed lines with saturated traffic. With two seating levels and a seating capacity of 508 passengers, the Duplex increases the passenger capacity. While the TGV Duplex started as a small component of the TGV fleet, it has become one of the system's workhorses; the LGV Sud-Est from Paris to Lyon is the busiest high-speed line in France. After its opening in 1981 it reached capacity. Several options were available to increase capacity; the separation between trains was reduced to three minutes on some TGV lines, but the complex signalling systems, high-performance brakes required, limited this option. Another option is to widen the train but is not practicable due to loading gauge restrictions. Running two trainsets coupled together in multiple-unit configuration provides extra capacity, but required long station platforms.
Given length and width restrictions, the remaining option is to adopt a bi-level configuration, with seating on two levels, adding 45% more passenger capacity. TGV Duplex sets are run with a single deck Réseau set or another Duplex set; the Duplex feasibility study was completed in 1987. In 1988, a full-scale mockup was built to gauge customer reactions to the bi-level concept, traditionally associated with commuter and regional rail rather than with high-speed intercity trains. A TGV Sud-Est trailer was tested in revenue service with the inside furnished to simulate the lower floor of a bi-level arrangement, that year another TGV Sud-Est was modified to study the dynamic behavior of a train with a higher center of gravity. Discussions with GEC-Alsthom began soon after, in July 1990 the company won the contract to build the "TGV-2N", as it was known; the contract was finalized in early 1991. The first tests of a bi-level trainset were in November 1994. Soon after their first run, the first rake of eight trailers was tested at 290 km/h on the Sud-Est line.
The trainset was powered by TGV Réseau power cars at the time, as the Duplex power cars were not ready. The first Duplex power car was mated to the bi-level trailers on 21 June 1995; the most important innovation is the efficiency of the Duplex design. Comparing an original TGV Sud-Est and a Duplex trainset shows that the double-decker design has improvements in both power-to-weight ratio and weight-per-seat overhead: In this comparison, "power" refers to installed power, not all of, used when operating. Aluminium bodies: the strict requirement of a 17-tonne axle load limit made it imperative to cut down on weight, wherever possible. Extruded aluminum construction made possible a 20% reduction in structure weight. Improved styling and aerodynamics: the nose of the power units and the gap between trailers were improved such that a Duplex train at cruise speed of 300 km/h experiences only 4% more drag than a single-level TGV; the nose, the first significant departure from Cooper's original design, was styled by industrial designer Roger Tallon, as was the rest of the trainset.
Crashworthiness: crush zones and rigid passenger compartments protect safety in the event of a collision. The power units' frame is designed to take a 500 tonnes of force frontal load, features structural fuses to absorb impact energy. Active pantograph: the Faiveley CX used on the Duplex has a pneumatically actuated active control system. Two small gas cylinders in the wiper armature can tune the stiffness of the pantograph's upper stage, to optimize contact at any speed. All wheel disc brakes: earlier TGVs used disc brakes only on unpowered axles. Weight gains on the Duplex power units allowed the installation of disc brakes directly on the wheels of powered axles, instead of using the traditional tread brakes; this does not improve braking performance, but it leaves the wheel tread smooth and reduces rolling noise. Quiet roof fans: the cooling fans in TGV power units produce the most noticeable sound when the train is in a station; the fans, located in the roof of the unit, were redesigned to be quieter.
World's fastest train: in 2007 a short formation TGV Duplex was fitted with distributed traction as used in the future generation AGV setting a new speed record of 574.8 km/h. Known as Réseau Duplex, they take the serial number 600; this version came into existence when the carriages of nineteen TGV-Réseau sets were used to create the TGV POS sets. The Réseau powercars of these sets, with some aerodynamic adjustments, joined new Duplex sets, they were the first series of "inter-recoupled series" TGV to achieve a sustainable basis by SNCF. Instead of ordering brand new POS sets, the railways modified a pre-existing order for 19 Duplex as follows: 19 sets of 8 Duplex-carriages, identical to the original TGV Duplex, to be powered by the 38 surplus TGV Réseau powercars. 38 new tri-current powercars, based on the Duplex-version, making them suitable for use on the Deutsche Bahn's and Swiss Federal Railways' networks. These were joined to the nineteen sets of Réseau carriages, renovated by Christian Lacroix, becoming the series "4400" or TGV POS.
Their livery is identical to that of other Duplex units. Called "duplex", these 19 units, number