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Wednesday, August 17, 2022

Hyperloop

From Wikipedia, the free encyclopedia
https://en.wikipedia.org/wiki/Hyperloop

Concept art of Hyperloop inner workings

A hyperloop is a proposed high-speed transportation system for both public and goods transport. The term was popularized by Elon Musk to describe a modern project based on the vactrain concept (first appearance 1799). Hyperloop systems comprise three essential elements: tubes, pods, and terminals. The tube is a large sealed, low-pressure system (usually a long tunnel). The pod is a coach pressurized at atmospheric pressure that runs substantially free of air resistance or friction inside this tube, using magnetic propulsion (in some cases augmented by a ducted fan). The terminal handles pod arrivals and departures. The Hyperloop, in the initial form proposed by Musk, differs from vactrains by relying on residual air pressure inside the tube to provide lift by aerofoils and propulsion by fans.

The hyperloop has its roots in a concept by George Medhurst in 1799 and subsequently developed under the names pneumatic railway, atmospheric railway or vactrain. Elon Musk renewed interest in hyperloop after mentioning it in a 2012 speaking event. Musk further promoted the concept by publishing a white paper in August 2013, which conceived of a hyperloop route running from the Los Angeles region to the San Francisco Bay Area, roughly following the Interstate 5 corridor. His initial concept incorporated reduced-pressure tubes in which pressurized capsules ride on air bearings driven by linear induction motors and axial compressors. Transportation analysts challenged the cost estimates included in the white paper, with some predicting that a realized hyperloop would be several billion dollars over budget.

The hyperloop concept has been promoted by Musk and SpaceX, and other companies or organizations have been encouraged to collaborate and develop the technology. Technical University of Munich Hyperloop set the hyperloop speed record of 463 km/h (288 mph) in July 2019 at the pod design competition hosted by SpaceX in Hawthorne, California. Virgin Hyperloop conducted the first human trial in November 2020 at its test site in Las Vegas, reaching a top speed of 172 km/h (107 mph).

History

After being conceived in 1799, the vactrain was invented in 1904 by Robert H. Goddard, a freshman at Worcester Polytechnic Institute.

Musk first mentioned that he was thinking about a concept for a "fifth mode of transport", calling it the Hyperloop, in July 2012 at a PandoDaily event in Santa Monica, California. This hypothetical high-speed mode of transportation would have the following characteristics: immunity to weather, collision free, twice the speed of a plane, low power consumption, and energy storage for 24-hour operations. The name Hyperloop was chosen because it would go in a loop. Musk envisions the more advanced versions will be able to go at hypersonic speed. In May 2013, Musk likened his Hyperloop to a "cross between a Concorde and a railgun and an air hockey table".

From late 2012 until August 2013, a group of engineers from both Tesla and SpaceX worked on the conceptual modeling of Musk's Hyperloop. An early system conceptual model was published in the Tesla and SpaceX blogs which describes one potential design, function, pathway, and cost of a hyperloop system. According to the alpha design, pods would accelerate to cruising speeds gradually using linear electric motors and glide above their track on air bearings through tubes above ground on columns or below ground in tunnels to avoid the dangers of grade crossings. An ideal hyperloop system will be more energy-efficient, quiet, and autonomous than existing modes of mass transit. Musk has also invited feedback to "see if the people can find ways to improve it". The Hyperloop Alpha was released as an open source design. The trademark "HYPERLOOP", applicable to "high-speed transportation of goods in tubes" was issued to SpaceX on 4 April 2017.

In June 2015, SpaceX announced that it would build a 1-mile-long (1.6 km) test track to be located next to SpaceX's Hawthorne facility. The track was completed and used to test pod designs supplied by third parties in the competition.

By November 2015, with several commercial companies and dozens of student teams pursuing the development of Hyperloop technologies, the Wall Street Journal asserted that "The Hyperloop Movement", as some of its unaffiliated members refer to themselves, is officially bigger than the man who started it."

The Massachusetts Institute of Technology (MIT) hyperloop team developed the first hyperloop pod prototype, which they unveiled at the MIT Museum on 13 May 2016. Their design uses electrodynamic suspension for levitating and eddy current braking.

On 29 January 2017, approximately one year after phase one of the hyperloop pod competition, the MIT Hyperloop pod demonstrated the first ever low-pressure hyperloop run in the world. Within this first competition the Delft University team from the Netherlands achieved the highest overall competition score, winning the prize for "best overall design". The award for the "fastest pod" was won by the Technical University of Munich (TUM), Germany, team WARR Hyperloop. The MIT team placed third overall in the competition, judged by SpaceX engineers.

The second hyperloop pod competition took place from 25 to 27 August 2017. The only judging criterion was top speed, provided it was followed by successful deceleration. The TUM WARR Hyperloop won the competition by reaching a top speed of 324 km/h (201 mph), breaking the previous record of 310 km/h (190 mph) for hyperloop prototypes set by Hyperloop One on their own test track.

A third hyperloop pod competition took place in July 2018. The defending champions, the TUM WARR hyperloop team, beat their own record with a top speed of 457 km/h (284 mph) during their run.

The fourth competition in August 2019 saw the TUM team, now known as TUM Hyperloop (by NEXT Prototypes e.V.), again winning the competition and beating their own record with a top speed of 463 km/h (288 mph).

The first passenger test of hyperloop technology was successfully conducted by Virgin Hyperloop with two employees of the company in November 2020, where the unit reached a maximum speed of 172 km/h (107 mph).

In 2022, journalist Paris Marx claimed that "Musk admitted to his biographer Ashlee Vance that Hyperloop was all about trying to get legislators to cancel plans for high-speed rail in California—even though he had no plans to build it."

Theory and operation

An artist's rendition of a Hyperloop capsule: Axial compressor on the front, passenger compartment in the middle, battery compartment at the back, and air caster skis at the bottom
 
A 3D sketch of potential Hyperloop infrastructure. The steel tubes are rendered transparent in this image.

The vactrain concept resembles a high-speed rail system without substantial air resistance by employing magnetically levitating trains in evacuated (airless) or partly evacuated tubes. However, the difficulty of maintaining a vacuum over large distances has prevented this type of system from ever being built. The hyperloop is similar to a vactrain system but operates at approximately one millibar (100 Pa) of pressure.

Initial design concept

The hyperloop concept operates by sending specially designed "capsules" or "pods" through a steel tube maintained at a partial vacuum. In Musk's original concept, each capsule would float on a 0.02–0.05 in (0.5–1.3 mm) layer of air provided under pressure to air-caster "skis", similar to how pucks are levitated above an air hockey table, while still allowing higher speeds than wheels can sustain. With rolling resistance eliminated and air resistance greatly reduced, the capsules can glide for the bulk of the journey. In the alpha design concept, an electrically driven inlet fan and axial compressor would be placed at the nose of the capsule to "actively transfer high-pressure air from the front to the rear of the vessel", resolving the problem of air pressure building in front of the vehicle, slowing it down. A fraction of the air was to be shunted to the skis for additional pressure, augmenting that gain passively from lift due to their shape.

In the alpha-level concept, passenger-only pods were to be 7 ft 4 in (2.23 m) in diameter and were projected to reach a top speed of 760 mph (1,220 km/h) to maintain aerodynamic efficiency. The design proposed passengers experience a maximum inertial acceleration of 0.5 g, about 2 or 3 times that of a commercial airliner on takeoff and landing.

Proposed routes

Interstate 5

A number of routes have been proposed for hyperloop systems that meet the approximate distance conditions for which a hyperloop is hypothesized to provide improved transport times (distances of under approximately 1,500 kilometres (930 miles)). Route proposals range from speculation described in company releases to business cases to signed agreements.

United States

The route suggested in the 2013 alpha-level design document was from the Greater Los Angeles Area to the San Francisco Bay Area. That conceptual system would begin around Sylmar, just south of the Tejon Pass, follow Interstate 5 to the north, and arrive near Hayward on the east side of San Francisco Bay. Several proposed branches were also shown in the design document, including Sacramento, Anaheim, San Diego, and Las Vegas.

No work has been done on the route proposed in Musk's alpha-design; one cited reason is that it would terminate on the fringes of the two major metropolitan areas (Los Angeles and San Francisco), resulting in significant cost savings in construction, but requiring that passengers traveling to and from Downtown Los Angeles and San Francisco, and any other community beyond Sylmar and Hayward, to transfer to another transportation mode in order to reach their final destination. This would significantly lengthen the total travel time to those destinations.

A similar problem already affects present-day air travel, where on short routes (like LAX–SFO) the flight time is only a rather small part of door to door travel time. Critics have argued that this would significantly reduce the proposed cost and/or time savings of hyperloop as compared to the California High-Speed Rail project that will serve downtown stations in both San Francisco and Los Angeles. Passengers traveling from financial center to financial center are estimated to save about two hours by taking the Hyperloop instead of driving the whole distance.

Others questioned the cost projections for the suggested California route. Some transportation engineers argued in 2013 that they found the alpha-level design cost estimates unrealistically low given the scale of construction and reliance on unproven technology. The technological and economic feasibility of the idea is unproven and a subject of significant debate.

In November 2017, Arrivo announced a concept for a maglev automobile transport system from Aurora, Colorado to Denver International Airport, the first leg of a system from downtown Denver. Its contract described potential completion of a first leg in 2021. In February 2018, Hyperloop Transportation Technologies announced a similar plan for a loop connecting Chicago and Cleveland and a loop connecting Washington and New York City.

In 2018 the Missouri Hyperloop Coalition was formed between Virgin Hyperloop One, the University of Missouri, and engineering firm Black & Veatch to study a proposed route connecting St. Louis, Columbia, and Kansas City.

On 19 December 2018, Elon Musk unveiled a 2-mile (3 km) tunnel below Los Angeles. In the presentation, a Tesla Model X drove in a tunnel on the predefined track (rather than in a low-pressure tube). According to Musk the costs for the system are US$10 million. Musk said: "The Loop is a stepping stone toward hyperloop. The Loop is for transport within a city. Hyperloop is for transport between cities, and that would go much faster than 150 mph."

The Northeast Ohio Areawide Coordinating Agency, or NOACA, partnered with Hyperloop Transportation Technologies to conduct a $1.3 million feasibility study for developing a hyperloop corridor route from Chicago to Cleveland and Pittsburgh for America's first multistate hyperloop system in the Great Lakes Megaregion. Hundreds of thousands of dollars already have been committed to the project. NOACA's Board of Directors has awarded a $550,029 contract to Transportation Economics & Management Systems, Inc. (TEMS) for the Great Lakes Hyperloop Feasibility Study to evaluate the feasibility of an ultra-high-speed hyperloop passenger and freight transport system initially linking Cleveland and Chicago.

India

Hyperloop Transportation Technologies were considering in 2016 with the Indian Government for a proposed route between Chennai and Bengaluru, with a conceptual travel time for 345 km (214 mi) of 30 minutes. HTT also signed an agreement with Andhra Pradesh government to build India's first hyperloop project connecting Amaravathi to Vijayawada in a 6-minute ride.

On 22 February 2018, Hyperloop One entered into a memorandum of understanding with the Government of Maharashtra to build a hyperloop transportation system between Mumbai and Pune that would cut the travel time from the current 180 minutes to 20 minutes.

Indore-based Dinclix GroundWorks' DGWHyperloop advocates a hyperloop corridor between Mumbai and Delhi, via Indore, Kota, and Jaipur.

The Ministry of Railways will collaborate with IIT Madras for the development of an "indigenous" Hyperloop system and will help set-up a Centre of Excellence for Hyperloop Technologies at IIT.

Saudi Arabia

On 6 February 2020, the Ministry of Transport in the Kingdom of Saudi Arabia announced a contract agreement with Virgin Hyperloop One (VHO) to conduct a ground-breaking pre-feasibility study on the use of hyperloop technology for the transport of passengers and cargo. The study will serve as a blueprint for future hyperloop projects and build on the developers long-standing relationship with the kingdom, which has peaked when His Royal Highness Prince Mohammed bin Salman Abdulaziz Al Saud, Crown Prince of Saudi Arabia, viewed VHO's passenger pod during a visit to the United States.

Italy

On 29 December 2021, the Veneto Regional Council approved a memorandum of understanding with MIMS and CAV for the testing of hyper transfer technology. By mid 2023, the feasibility study by a company selected by CAV will have to be completed and the development of a first prototype completed in 2026. 4 million euro have been allocated for this phase.

Elsewhere in the world

Many of the active Hyperloop routes that have been considered are outside of the US. In 2016, Hyperloop One published the world's first detailed business case for a 300-mile (500 km) route between Helsinki and Stockholm, which would tunnel under the Baltic Sea to connect the two capitals in under 30 minutes. Hyperloop One undertook a feasibility study with DP World to move containers from its Port of Jebel Ali in Dubai. In late 2016, Hyperloop One announced a feasibility study with Dubai's Roads and Transport Authority for passenger and freight routes connecting Dubai with the greater United Arab Emirates. Hyperloop One was also considering passenger routes in Moscow during 2016, and a cargo hyperloop to connect Hunchun in north-eastern China to the Port of Zarubino, near Vladivostok and the North Korean border on Russia's Far East. In May 2016, Hyperloop One kicked off their Global Challenge with a call for comprehensive proposals of hyperloop networks around the world. In September 2017, Hyperloop One selected 10 routes from 35 of the strongest proposals: TorontoMontreal, CheyenneDenverPueblo, MiamiOrlando, DallasLaredoHouston, ChicagoColumbusPittsburgh, Mexico CityGuadalajara, EdinburghLondon, GlasgowLiverpool, BengaluruChennai, and MumbaiChennai.

Others have put forward European routes, including a route beginning at Amsterdam or Schiphol to Frankfurt. In 2016, a Warsaw University of Technology team began evaluating potential routes from Cracow to Gdańsk across Poland proposed by Hyper Poland.

TransPod explored the possibility of hyperloop routes which would connect Toronto and Montreal, Toronto to Windsor, and Calgary to Edmonton. Toronto and Montreal, the largest cities in Canada, are currently connected by Ontario Highway 401, the busiest highway in North America. In March 2019, Transport Canada commissioned the study of hyperloops, so it can be "better informed on the technical, operational, economic, safety, and regulatory aspects of the hyperloop and understand its construction requirements and commercial feasibility."

Hyperloop Transportation Technologies (HTT) reportedly signed an agreement with the government of Slovakia in March 2016 to perform impact studies, with potential links between Bratislava, Vienna, and Budapest, but there have been no further developments. In January 2017, HTT signed an agreement to explore the route BratislavaBrnoPrague in Central Europe.

In 2017, SINTEF, the largest independent research organization in Scandinavia, announced they were considering building a test lab for hyperloop in Norway.

An agreement was signed in June 2017 to co-develop a hyperloop line between Seoul and Busan in South Korea.

Mars

According to Musk, hyperloop would be useful on Mars as no tubes would be needed because Mars' atmosphere is about 1% the density of the Earth's at sea level. For the hyperloop concept to work on Earth, low-pressure tubes are required to reduce air resistance. However, if they were to be built on Mars, the lower air resistance would allow a hyperloop to be created with no tube, only a track, and so would be just a magnetically levitating train.

Open-source design evolution

In September 2013, Ansys Corporation ran computational fluid dynamics simulations to model the aerodynamics of the capsule and shear stress forces that the capsule would be subjected to. The simulation showed that the capsule design would need to be significantly reshaped to avoid creating supersonic airflow, and that the gap between the tube wall and capsule would need to be larger. Ansys employee Sandeep Sovani said the simulation showed that hyperloop has challenges but that he is convinced it is feasible.

In October 2013, the development team of the OpenMDAO software framework released an unfinished, conceptual open-source model of parts of the hyperloop's propulsion system. The team asserted that the model demonstrated the concept's feasibility, although the tube would need to be 13 feet (4 m) in diameter, significantly larger than originally projected. However, the team's model is not a true working model of the propulsion system, as it did not account for a wide range of technical factors required to physically construct a hyperloop based on Musk's concept, and in particular had no significant estimations of component weight.

In November 2013, MathWorks analyzed the proposal's suggested route and concluded that the route was mainly feasible. The analysis focused on the acceleration experienced by passengers and the necessary deviations from public roads in order to keep the accelerations reasonable; it did highlight that maintaining a trajectory along I-580 east of San Francisco at the planned speeds was not possible without significant deviation into heavily populated areas.

In January 2015, a paper based on the NASA OpenMDAO open-source model reiterated the need for a larger diameter tube and a reduced cruise speed closer to Mach 0.85. It recommended removing on-board heat exchangers based on thermal models of the interactions between the compressor cycle, tube, and ambient environment. The compression cycle would only contribute 5% of the heat added to the tube, with 95% of the heat attributed to radiation and convection into the tube. The weight and volume penalty of on-board heat exchangers would not be worth the minor benefit, and regardless the steady-state temperature in the tube would only reach 30–40 °F (17–22 °C) above ambient temperature.

According to Musk, various aspects of the hyperloop have technology applications to other Musk interests, including surface transportation on Mars and electric jet propulsion.

Researchers associated with MIT's department of Aeronautics and Astronautics published research in June 2017 that verified the challenge of aerodynamic design near the Kantrowitz limit that had been theorized in the original SpaceX Alpha-design concept released in 2013.

In 2017, Dr. Richard Geddes and others formed the Hyperloop Advanced Research Partnership to act as a clearinghouse of Hyperloop public domain reports and data.

In February 2020, Hardt Hyperloop, Hyper Poland, TransPod and Zeleros formed a consortium to drive standardisation efforts, as part of a joint technical committee (JTC20) set up by European standards bodies CEN and CENELEC to develop common standards aimed at ensuring the safety and interoperability of infrastructure, rolling stock, signalling and other systems.

Hyperloop research programs

TUM Hyperloop (previously WARR Hyperloop)

TUM Hyperloop is a research program that emerged in 2019 from the team of hyperloop pod competition from the Technical University of Munich. The TUM Hyperloop team had won all four competitions in a row, achieving the world record of 463 km/h (288 mph), which is still valid today. The research program has the goals to investigate the technical feasibility by means of a demonstrator, as well as by simulation the economic and technical feasibility of the hyperloop system. The planned 24m demonstrator will consist of a tube and the full-size pod. The next steps after completion of the first project phase are the extension to 400m to investigate higher speeds. This is planned in the Munich area, in Taufkirchen, Ottobrunn or at the Oberpfaffenhofen airfield.

Eurotube

EuroTube is a non-profit research organization for the development of vacuum transport technology. EuroTube is currently developing a 3.1 km (1.9 mi) test tube in Collombey-Muraz, Switzerland. The organization was founded in 2017 at ETH Zurich as a Swiss association and became a Swiss foundation in 2019. The test tube is planned on a 2:1 scale with a diameter of 2.2 m and designed for 900 km/h (560 mph).

Hyperloop pod competition

Hyperloop pod competition

A number of student and non-student teams were participating in a hyperloop pod competition in 2015–16, and at least 22 of them built hardware to compete on a sponsored hyperloop test track in mid-2016.

In June 2015, SpaceX announced that they would sponsor a hyperloop pod design competition, and would build a 1-mile-long (1.6 km) subscale test track near SpaceX's headquarters in Hawthorne, California, for the competitive event in 2016. SpaceX stated in their announcement, "Neither SpaceX nor Elon Musk is affiliated with any Hyperloop companies. While we are not developing a commercial Hyperloop ourselves, we are interested in helping to accelerate development of a functional Hyperloop prototype."

More than 700 teams had submitted preliminary applications by July, and detailed competition rules were released in August. Intent to Compete submissions were due in September 2015 with more detailed tube and technical specification released by SpaceX in October. A preliminary design briefing was held in November 2015, where more than 120 student engineering teams were selected to submit Final Design Packages due by 13 January 2016.

A Design Weekend was held at Texas A&M University 29–30 January 2016, for all invited entrants. Engineers from the Massachusetts Institute of Technology were named the winners of the competition. While the University of Washington team won the Safety Subsystem Award, Delft University won the Pod Innovation Award as well as the second place, followed by the University of Wisconsin–Madison, Virginia Tech, and the University of California, Irvine. In the Design Category, the winner team was Hyperloop UPV from Universitat Politecnica de Valencia, Spain. On 29 January 2017, Delft Hyperloop (Delft University of Technology) won the prize for the "best overall design" at the final stage of the SpaceX hyperloop competition, while WARR Hyperloop of the Technical University of Munich won the prize for "fastest pod". The Massachusetts Institute of Technology placed third.

The second hyperloop pod competition took place from 25 to 27 August 2017. The only judging criteria being top speed provided it is followed by successful deceleration. WARR Hyperloop from the Technical University of Munich won the competition by reaching a top speed of 324 km/h (201 mph).

A third hyperloop pod competition took place in July 2018. The defending champions, the WARR Hyperloop team from the Technical University of Munich, beat their own record with a top speed of 457 km/h (284 mph) during their run. The fourth competition in August 2019 saw the team from the Technical University of Munich, now known as TUM Hyperloop (by NEXT Prototypes e.V.), again winning the competition and beating their own record with a top speed of 463 km/h (288 mph).

Criticism and human factor considerations

Some critics of hyperloop focus on the experience—possibly unpleasant and frightening—of riding in a narrow, sealed, windowless capsule inside a sealed steel tunnel, that is subjected to significant acceleration forces; high noise levels due to air being compressed and ducted around the capsule at near-sonic speeds; and the vibration and jostling. Even if the tube is initially smooth, ground may shift with seismic activity. At high speeds, even minor deviations from a straight path may add considerable buffeting. This is in addition to practical and logistical questions regarding how to best deal with safety issues such as equipment malfunction, accidents, and emergency evacuations.

Other maglev trains are already in use, which avoid much of the added costs of hyperloop. The SCMaglev in Japan has demonstrated 603 km/h (375 mph) without a vacuum tube, by using an extremely aerodynamic train design. It also avoids the cost and time required to pressurize and depressurize the exit and entry points of a hyperloop tube.

There is also the criticism of design technicalities in the tube system. John Hansman, professor of aeronautics and astronautics at MIT, has stated problems, such as how a slight misalignment in the tube would be compensated for and the potential interplay between the air cushion and the low-pressure air. He has also questioned what would happen if the power were to go out when the pod was miles away from a city. UC Berkeley physics professor Richard Muller has also expressed concern regarding "[the Hyperloop's] novelty and the vulnerability of its tubes, [which] would be a tempting target for terrorists", and that the system could be disrupted by everyday dirt and grime.

Political and economic considerations

The alpha proposal projected that cost savings compared with conventional rail would come from a combination of several factors. The small profile and elevated nature of the alpha route would enable hyperloop to be constructed primarily in the median of Interstate 5. However, whether this would be truly feasible is a matter of debate. The low profile would reduce tunnel boring requirements and the light weight of the capsules is projected to reduce construction costs over conventional passenger rail. It was asserted that there would be less right-of-way opposition and environmental impact as well due to its small, sealed, elevated profile versus that of a rail easement; however, other commentators contend that a smaller footprint does not guarantee less opposition. In criticizing this assumption, mass transportation writer Alon Levy said, "In reality, an all-elevated system (which is what Musk proposes with the Hyperloop) is a bug rather than a feature. Central Valley land is cheap; pylons are expensive, as can be readily seen by the costs of elevated highways and trains all over the world". Michael Anderson, a professor of agricultural and resource economics at UC Berkeley, predicted that costs would amount to around US$100 billion.

No total ticket price was suggested in the alpha design in Elon Musk's initial whitepaper. Projected low ticket prices by hyperloop developers have been questioned by Dan Sperling, director of the Institute of Transportation Studies at UC Davis, who stated that "there's no way the economics on that would ever work out." Some critics have argued that, since hyperloops are designed to carry fewer passengers than typical public train systems, it could make it difficult to price tickets to cover the costs of construction and running.

The early cost estimates of the hyperloop are a subject of debate. A number of economists and transportation experts have expressed the belief that the US$6 billion price tag dramatically understates the cost of designing, developing, constructing, and testing an all-new form of transportation. The Economist said that the estimates are unlikely to "be immune to the hypertrophication of cost that every other grand infrastructure project seems doomed to suffer."

Political impediments to the construction of such a project in California will be very large. There is a great deal of "political and reputation capital" invested in the existing mega-project of California High-Speed Rail. Replacing that with a different design would not be straightforward given California's political economy. Texas has been suggested as an alternate for its more amenable political and economic environment. In August 2022, Time.com and Gizmodo published that the Hyperloop announcement could have been a attempt to discourage the California High-Speed Rail project.

Building a successful hyperloop sub-scale demonstration project could reduce the political impediments and improve cost estimates. Musk has suggested that he may be personally involved in building a demonstration prototype of the hyperloop concept, including funding the development effort.

The solar panels Musk plans to install along the length of the hyperloop system have been criticized by engineering professor Roger Goodall of Loughborough University, as not being feasible enough to return enough energy to power the hyperloop system, arguing that the air pumps and propulsion would require much more power than the solar panels could generate.

Hyperloop companies


Company Name Country Est. Fate Notes
Virgin Hyperloop U.S. 2014 Active Ended development of passenger travel in February 2022 to focus on freight
Hyperloop Transportation Technologies U.S. 2013 Active
Transpod Canada, France 2015 Active
DGWHyperloop India 2015 Active
Arrivo U.S. 2016 Defunct Ended hyperloop development in November 2017 in favor of maglev
Hardt Global Mobility Netherlands 2016 Active
Zeleros Spain 2016 Active
Nemovo Poland 2017 Active Named Hyper Poland until November 2020

Related projects

Historical

The concept of transportation of passengers in pneumatic tubes is not new. The first patent to transport goods in tubes was created in 1799 by the British mechanical engineer and inventor George Medhurst. In 1812, Medhurst wrote a book detailing his idea of transporting passengers and goods through air-tight tubes using air propulsion.

In the early 1800s, there were other similar systems proposed or experimented with and were generally known as atmospheric railway projects, though this term is now also used for systems where the propulsion is provided by a separate pneumatic tube to the train tunnel itself.

One of the earliest constructions was the Dalkey Atmospheric Railway which operated near Dublin between 1844 and 1854.

The Crystal Palace pneumatic railway operated in London around 1864 and used large fans, some 22 ft (6.7 m) in diameter, that were powered by a steam engine. The tunnels are now lost but the line operated successfully for over a year.

Operated from 1870 to 1873, the Beach Pneumatic Transit was a one-block-long prototype of an underground tube transport public transit system in New York City. The system worked at near-atmospheric pressure, and the passenger car moved by means of higher pressure air applied to the back of the car while comparatively lower pressure air was maintained on the front of the car.

In the 1910s, vacuum trains were first described by American rocket pioneer Robert Goddard. While the hyperloop has significant innovations over early proposals for reduced pressure or vacuum-tube transportation apparatus, the work of Goddard "appears to have the greatest overlap with the Hyperloop".

In 1981, Princeton physicist Gerard K. O'Neill wrote about transcontinental trains using magnetic propulsion in his book 2081: A Hopeful View of the Human Future. Though being a work of fiction, this book was an attempt to predict future technologies in everyday life. In his prediction, he envisioned these trains which used magnetic levitation running in tunnels which had much of the air evacuated to increase speed and significantly reduce friction. He also demonstrated a scale prototype device that accelerated an object using magnetic propulsion to high speeds. It was called a mass driver and was a central theme in his non-fiction book on space colonization "The High Frontier".

Swissmetro was a proposal to run a maglev train in a low-pressure environment. Concessions were granted to Swissmetro in the early 2000s to connect the Swiss cities of St. Gallen, Zurich, Basel, and Geneva. Studies of commercial feasibility reached differing conclusions and the vactrain was never built.

The ET3 Global Alliance (ET3) was founded by Daryl Oster in 1997 with the goal of establishing a global transportation system using passenger capsules in frictionless maglev full-vacuum tubes. Oster and his team met with Elon Musk on 18 September 2013, to discuss the technology, resulting in Musk promising an investment in a 3-mile (5 km) prototype of ET3's proposed design.

From 2003 Franco Cotana led the development of Pipenet which had a small bore evacuated tube for moving freight at up to 2,000 km/h (1,200 mph) using linear synchronous motors and magnetic levitation. A prototype system - 100 m (110 yd) long and 1.25 m (1.37 yd) in diameter - was constructed in Italy in 2005. However development stopped after funding ceased.

China was reported to be building a vacuum based 600 mph (1,000 km/h) maglev train in August 2010 according to a laboratory at Southwest Jiaotong University. It was expected to cost CN¥10–20 million (US$2.95 million at the August 2010 exchange rate) more per kilometer than regular high-speed rail. In 2018 a 45 m (49 yd) loop test track was completed to test some of the technology.

In 2018, the new concept of creating and using intermodal hyperloop capsules was presented. After detaching the drive elements, capsules could be used in a way similar to traditional containers for fast transport of goods or individuals. It has been proposed that specialized airplanes, dedicated high-speed trains, road tractors or watercrafts perform "last mile" transport for solving the problem of fast transportation to centers where hyperloop terminals are locally unavailable or infeasible to be constructed.

In May 2021, it was reported that a low-vacuum sealed tube test system capable of reaching speeds around 1,000 km/h (620 mph) had begun construction in Datong, Shanxi Province. An initial 2 km (1.2 mi) section is to be completed by July 2022 and a 15 km (9.3 mi) test line within two years. The line will be built by the North University of China and the Third Research Institute of China Aerospace Science and Industry Corporation.

Neodymium magnet

From Wikipedia, the free encyclopedia
 
A Nickel-plated neodymium magnet on a bracket from a hard disk drive
 
Nickel-plated neodymium magnet cubes
 
Left: high-resolution transmission electron microscopy image of Nd2Fe14B; right: crystal structure with unit cell marked

A neodymium magnet (also known as NdFeB, NIB or Neo magnet) is the most widely used type of rare-earth magnet. It is a permanent magnet made from an alloy of neodymium, iron, and boron to form the Nd2Fe14B tetragonal crystalline structure. Developed independently in 1984 by General Motors and Sumitomo Special Metals, neodymium magnets are the strongest type of permanent magnet available commercially.

NdFeB magnets can be classified as sintered or bonded, depending on the manufacturing process used. They have replaced other types of magnets in many applications in modern products that require strong permanent magnets, such as electric motors in cordless tools, hard disk drives and magnetic fasteners.

History

General Motors (GM) and Sumitomo Special Metals independently discovered the Nd2Fe14B compound almost simultaneously in 1984. The research was initially driven by the high raw materials cost of SmCo permanent magnets, which had been developed earlier. GM focused on the development of melt-spun nanocrystalline Nd2Fe14B magnets, while Sumitomo developed full-density sintered Nd2Fe14B magnets.

GM commercialized its inventions of isotropic Neo powder, bonded neo magnets, and the related production processes by founding Magnequench in 1986 (Magnequench has since become part of Neo Materials Technology, Inc., which later merged into Molycorp). The company supplied melt-spun Nd2Fe14B powder to bonded magnet manufacturers. The Sumitomo facility became part of the Hitachi Corporation, and has manufactured but also licensed other companies to produce sintered Nd2Fe14B magnets. Hitachi has held more than 600 patents covering neodymium magnets.

Chinese manufacturers have become a dominant force in neodymium magnet production, based on their control of much of the world's rare-earth mines.

The United States Department of Energy has identified a need to find substitutes for rare-earth metals in permanent magnet technology and has funded such research. The Advanced Research Projects Agency-Energy has sponsored a Rare Earth Alternatives in Critical Technologies (REACT) program, to develop alternative materials. In 2011, ARPA-E awarded 31.6 million dollars to fund Rare-Earth Substitute projects. Because of its role in permanent magnets used for wind turbines, it has been argued that neodymium will be one of the main objects of geopolitical competition in a world running on renewable energy. This perspective has been criticized for failing to recognize that most wind turbines do not use permanent magnets and for underestimating the power of economic incentives for expanded production.

Explanation of strength

In its pure form, neodymium has magnetic properties—specifically, it is antiferromagnetic—but only at temperatures, below 19 K (−254.2 °C; −425.5 °F). Neodymium magnets are made from compounds of neodymium with transition metals such as iron that are ferromagnetic, with Curie temperatures well above room temperature.

The strength of neodymium magnets is the result of several factors. The most important is that the tetragonal Nd2Fe14B crystal structure has exceptionally high uniaxial magnetocrystalline anisotropy (HA ≈ 7 T – magnetic field strength H in units of A/m versus magnetic moment in A·m2). This means a crystal of the material preferentially magnetizes along a specific crystal axis but is very difficult to magnetize in other directions. Like other magnets, the neodymium magnet alloy is composed of microcrystalline grains which are aligned in a powerful magnetic field during manufacture so their magnetic axes all point in the same direction. The resistance of the crystal lattice to turning its direction of magnetization gives the compound a very high coercivity, or resistance to being demagnetized.

The neodymium atom can have a large magnetic dipole moment because it has 4 unpaired electrons in its electron structure as opposed to (on average) 3 in iron. In a magnet it is the unpaired electrons, aligned so that their spin is in the same direction, which generate the magnetic field. This gives the Nd2Fe14B compound a high saturation magnetization (Js ≈ 1.6 T or 16 kG) and a remnant magnetization of typically 1.3 teslas. Therefore, as the maximum energy density is proportional to Js2, this magnetic phase has the potential for storing large amounts of magnetic energy (BHmax ≈ 512 kJ/m3 or 64 MG·Oe).

This magnetic energy value is about 18 times greater than "ordinary" ferrite magnets by volume and 12 times by mass. This magnetic energy property is higher in NdFeB alloys than in samarium cobalt (SmCo) magnets, which were the first type of rare-earth magnet to be commercialized. In practice, the magnetic properties of neodymium magnets depend on the alloy composition, microstructure, and manufacturing technique employed.

The Nd2Fe14B crystal structure can be described as alternating layers of iron atoms and a neodymium-boron compound. The diamagnetic boron atoms do not contribute directly to the magnetism but improve cohesion by strong covalent bonding. The relatively low rare earth content (12% by volume, 26.7% by mass) and the relative abundance of neodymium and iron compared with samarium and cobalt makes neodymium magnets lower in price than samarium-cobalt magnets.

Properties

Neodymium magnets (small cylinders) lifting steel spheres. Such magnets can easily lift thousands of times their own weight.
 
Ferrofluid on a glass plate displays the strong magnetic field of the neodymium magnet underneath.

Grades

Neodymium magnets are graded according to their maximum energy product, which relates to the magnetic flux output per unit volume. Higher values indicate stronger magnets. For sintered NdFeB magnets, there is a widely recognized international classification. Their values range from 28 up to 52. The first letter N before the values is short for neodymium, meaning sintered NdFeB magnets. Letters following the values indicate intrinsic coercivity and maximum operating temperatures (positively correlated with the Curie temperature), which range from default (up to 80 °C or 176 °F) to TH (230 °C or 446 °F).

Grades of sintered NdFeB magnets:

  • N30 – N55
  • N30M – N50M
  • N30H – N50H
  • N30SH – N48SH
  • N30UH – N42UH
  • N28EH – N40EH
  • N28TH – N35TH

Magnetic properties

Some important properties used to compare permanent magnets are:

Neodymium magnets have higher remanence, much higher coercivity and energy product, but often lower Curie temperature than other types of magnets. Special neodymium magnet alloys that include terbium and dysprosium have been developed that have higher Curie temperature, allowing them to tolerate higher temperatures. The table below compares the magnetic performance of neodymium magnets with other types of permanent magnets.

Magnet Br
(T)
Hci
(kA/m)
BHmax
(kJ/m3)
TC
(°C) (°F)
Nd2Fe14B, sintered 1.0–1.4 750–2000 200–440 310–400 590–752
Nd2Fe14B, bonded 0.6–0.7 600–1200 60–100 310–400 590–752
SmCo5, sintered 0.8–1.1 600–2000 120–200 720 1328
Sm(Co, Fe, Cu, Zr)7, sintered 0.9–1.15 450–1300 150–240 800 1472
Alnico, sintered 0.6–1.4 275 10–88 700–860 1292–1580
Sr-ferrite, sintered 0.2–0.78 100–300 10–40 450 842

Physical and mechanical properties

Photomicrograph of NdFeB. The jagged edged regions are the metal crystals, and the stripes within are the magnetic domains.
 
Comparison of physical properties of sintered neodymium and Sm-Co magnets
Property Neodymium Sm-Co
Remanence (T) 1–1.5 0.8–1.16
Coercivity (MA/m) 0.875–2.79 0.493–2.79
Recoil permeability 1.05 1.05–1.1
Temperature coefficient of remanence (%/K) −(0.12–0.09) −(0.05–0.03)
Temperature coefficient of coercivity (%/K) −(0.65–0.40) −(0.30–0.15)
Curie temperature (°C) 310–370 700–850
Density (g/cm3) 7.3–7.7 8.2–8.5
Thermal expansion coefficient, parallel to magnetization (1/K) (3–4)×10−6 (5–9)×10−6
Thermal expansion coefficient, perpendicular to magnetization (1/K) (1–3)×10−6 (10–13)×10−6
Flexural strength (N/mm2) 200–400 150–180
Compressive strength (N/mm2) 1000–1100 800–1000
Tensile strength (N/mm2) 80–90 35–40
Vickers hardness (HV) 500–650 400–650
Electrical resistivity (Ω·cm) (110–170)×10−6 (50–90)×10−6

Corrosion problems

These neodymium magnets corroded severely after five months of weather exposure.

Sintered Nd2Fe14B tends to be vulnerable to corrosion, especially along grain boundaries of a sintered magnet. This type of corrosion can cause serious deterioration, including crumbling of a magnet into a powder of small magnetic particles, or spalling of a surface layer.

This vulnerability is addressed in many commercial products by adding a protective coating to prevent exposure to the atmosphere. Nickel plating or two-layered copper-nickel plating are the standard methods, although plating with other metals, or polymer and lacquer protective coatings, are also in use.

Temperature effects

Neodymium has a negative coefficient, meaning the coercivity along with the magnetic energy density (BHmax) decreases with temperature. Neodymium-iron-boron magnets have high coercivity at room temperature, but as the temperature rises above 100 °C (212 °F), the coercivity decreases drastically until the Curie temperature (around 320 °C or 608 °F). This fall in coercivity limits the efficiency of the magnet under high-temperature conditions such as in wind turbines, hybrid motors, etc. Dysprosium (Dy) or terbium (Tb) is added to curb the fall in performance from temperature changes, making the magnet even more expensive.

Hazards

The greater forces exerted by rare-earth magnets create hazards that may not occur with other types of magnet. Neodymium magnets larger than a few cubic centimeters are strong enough to cause injuries to body parts pinched between two magnets, or a magnet and a ferrous metal surface, even causing broken bones.

Magnets that get too near each other can strike each other with enough force to chip and shatter the brittle magnets, and the flying chips can cause various injuries, especially eye injuries. There have even been cases where young children who have swallowed several magnets have had sections of the digestive tract pinched between two magnets, causing injury or death. Also this could be a serious health risk if working with machines that have magnets in or attached to them.

The stronger magnetic fields can be hazardous to mechanical and electronic devices, as they can erase magnetic media such as floppy disks and credit cards, and magnetize watches and the shadow masks of CRT type monitors at a greater distance than other types of magnet. In some cases, chipped magnets can act as a fire hazard as they come together, sending sparks flying as if they were a lighter flint, because some neodymium magnets contain ferrocerium.

Production

There are two principal neodymium magnet manufacturing methods:

  • Classical powder metallurgy or sintered magnet process
    • Sintered Nd-magnets are prepared by the raw materials being melted in a furnace, cast into a mold and cooled to form ingots. The ingots are pulverized and milled; the powder is then sintered into dense blocks. The blocks are then heat-treated, cut to shape, surface treated and magnetized.
  • Rapid solidification or bonded magnet process
    • Bonded Nd-magnets are prepared by melt spinning a thin ribbon of the NdFeB alloy. The ribbon contains randomly oriented Nd2Fe14B nano-scale grains. This ribbon is then pulverized into particles, mixed with a polymer, and either compression- or injection-molded into bonded magnets.

In 2015, Nitto Denko Corporation of Japan announced their development of a new method of sintering neodymium magnet material. The method exploits an "organic/inorganic hybrid technology" to form a clay-like mixture that can be fashioned into various shapes for sintering. Most importantly, it is said to be possible to control a non-uniform orientation of the magnetic field in the sintered material to locally concentrate the field to, e.g., improve the performance of electric motors. Mass production is planned for 2017.

As of 2012, 50,000 tons of neodymium magnets are produced officially each year in China, and 80,000 tons in a "company-by-company" build-up done in 2013. China produces more than 95% of rare earth elements and produces about 76% of the world's total rare-earth magnets, as well as most of the world's neodymium.

Applications

Existing magnet applications

Ring magnets
 
Most hard disk drives incorporate strong magnets
 
This manually-powered flashlight uses a neodymium magnet to generate electricity

Neodymium magnets have replaced alnico and ferrite magnets in many of the myriad applications in modern technology where strong permanent magnets are required, because their greater strength allows the use of smaller, lighter magnets for a given application. Some examples are:

  • Electric generators for wind turbines (only those with permanent magnet excitation)
  • Voice coil
  • Retail media case decouplers
  • In process industries, powerful neodymium magnets are used to catch foreign bodies and protect product and processes

New applications

Neodymium magnet spheres assembled in the shape of a cube

The greater strength of neodymium magnets has inspired new applications in areas where magnets were not used before, such as magnetic jewelry clasps, children's magnetic building sets (and other neodymium magnet toys) and as part of the closing mechanism of modern sport parachute equipment. They are the main metal in the formerly popular desk-toy magnets, "Buckyballs" and "Buckycubes", though some U.S. retailers have chosen not to sell them because of child-safety concerns, and they have been banned in Canada for the same reason.

The strength and magnetic field homogeneity on neodymium magnets has also opened new applications in the medical field with the introduction of open magnetic resonance imaging (MRI) scanners used to image the body in radiology departments as an alternative to superconducting magnets that use a coil of superconducting wire to produce the magnetic field.

Neodymium magnets are used as a surgically placed anti-reflux system which is a band of magnets surgically implanted around the lower esophageal sphincter to treat gastroesophageal reflux disease (GERD). They have also been implanted in the fingertips in order to provide sensory perception of magnetic fields, though this is an experimental procedure only popular among biohackers and grinders.

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