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Chinese company plans hyperloop traveling at 1,000 km/h
By Zhao Lei | chinadaily.com.cn | Updated: 2017-08-30 11:14
China Science & Technology Forum
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Astronomers recover a lost nova
First observed 600 years ago, this binary system is providing vital clues to how novae work.
Published: Wednesday, August 30, 2017
In the tail of Scorpius the Scorpion, a new star appeared briefly nearly 600 years ago. The year was 1437, and the previously unseen star, which flared bright and lasted 14 days before disappearing, was recorded by Korean astrologers at the time. Lost to astronomers hunting for its source since that date, the binary star system that underwent that nova has now been found.
The work, published today in Nature, describes “the first nova that's ever been recovered with certainty based on the Chinese, Korean, and Japanese records of almost 2,500 years,” according to lead author Michael Shara, a curator in the American Museum of Natural History's Department of Astrophysics, in a press release. Rediscovering this nova, which now appears to undergo periodic smaller-scale nova explosions, provides key support for the theory that novae have long life cycles, and can go dormant before ramping up again.
A nova differs from a supernova in that the former is not a catastrophic event that destroys its progenitor star. In a nova system, a white dwarf (the remnant of a star like our Sun) pulls material off a companion star, which is still in the hydrogen-burning phase of its life. This material, mostly hydrogen, piles up slowly over the course of something like 100,000 years, until it reaches a critical point. At that point, the hydrogen envelope suddenly fuses into helium, releasing a huge amount of energy that’s seen as a nova. It’s essentially a giant hydrogen bomb, and the white dwarf can shine several hundred thousand times brighter for days or even months afterward.
In a type Ia supernova, which occurs in similar systems, it’s thought that the white dwarf pulls matter off its companion much more quickly, and reaches a critical mass point that triggers a larger explosion, which does tear the white dwarf apart. Thus, supernovae destroy the stellar remnant that creates them; novae do not, allowing the process of hydrogen buildup to occur again and possibly trigger another nova in the future.
The nova of 1437 has been elusive, with several astronomers including Shara, Richard Stephenson of Durham University, and Mike Bode of Liverpool John Moores University searching for the binary system that caused it.
But recently, after expanding their initial search area, they came across a shell of material: the sign of a classical nova explosion. They even found a bright star near — but not in — the center of the shell.
The team cross-referenced their find with an image of the area taken at the Harvard Observatory station in Peru in 1923, and were able to accurately chart the star’s motion across the sky over time. Based on their calculations, “… we traced it back six centuries, and bingo, there it was, right at the center of our shell. That's the clock, that's what convinced us that it had to be right,” said Shara.
That photographic plate is now part of the Digitizing a Sky Century at Harvard (DASCH) project. And with the addition of other plates from the DASCH project taken in the 1940s, Shara and his team discovered that the nova is now something called a “dwarf nova,” which undergoes periodic small outbursts that are likely due to instabilities in the material as it forms a disk around and accretes onto the white dwarf, rather than the huge explosion of a “classical nova,” like the event it underwent nearly 600 years ago.
This behavior helps to cement the idea that classical novae, dwarf novae, and other objects that show novae-like variability are all different stages of the same type of system. “In the same way that an egg, a caterpillar, a pupa, and a butterfly are all life stages of the same organism, we now have strong support for the idea that these binaries are all the same thing seen in different phases of their lives,” Shara explained.
However, because these systems can evolve and change over hundreds of thousands of years, showing different types of behavior at different times, it’s been difficult to link them together. “We simply haven't been around long enough to see a single complete cycle,” said Shara.
But now, the rediscovery of the 1437 eruption and the ability to trace its evolution over time, astronomers can take a closer, more complete look at that life cycle to approach a better understanding of how systems that may seem different are really all one and the same.
▲ This Hα image was taken with the Swope 1-metre telescope and its CCD camera in June 2016, with a total of 6,000 seconds of exposure. Images taken by Swope were processed and combined with standard PyRAF and IRAF procedures. Here, north is up and east is to the left. The location of the cataclysmic variable in 2016 is indicated with red tick marks. Its proper motion places the AD 1437 cataclysmic variable 7.4″ east and 16.0″ north of its current position, at the red plus sign. The position of the centre of the shell in 2016 and its deduced position in 1437 (see text) are indicated with blue and green plus signs, respectively. The 1437 positions of the shell centre and of the cataclysmic variable agree to within 1.7″, and their 1σ error ellipses overlap.
▲ The Harvard photographic plate A12425, part of which is shown here, is a 300-minute exposure obtained using the 24″ Bruce Doublet telescope at the Harvard Observatory station in Arequipa, Peru. North is up; east is to the left; and the cataclysmic variable is indicated with red tick marks.
▲ The grey symbols show upper limits, while the black dots are measured DASCH detections of the star, with typical 1σ errors of ±0.1–0.2 mag. The star was first detected in quiescence near magnitude 17 in 1923, and near magnitude 16 in 1925. Dwarf-nova outbursts in 1934 (reaching nearly magnitude 12), 1935 and 1942 (see Fig. 4) are evident.
▲ The star is seen to undergo a dwarf-nova eruption, brightening substantially between the first and third images, then returning to quiescence a few days later. The dwarf nova is indicated with an arrow in each epoch in this series of Harvard DASCH MF-series photographic plates (see Methods). North is up and east is to the left.
▲ Published on Aug 31, 2017: '별 폭발' 세종실록으로 풀었다 / SBS 조선 시대에도 천문학이 발달했던 걸로 알려졌지요. 당시 천문관들이 밤하늘을 관측해 세종실록에 꼼꼼히 적어놨는데 600년 전의 이 기록들 덕분에 얼마 전 별 폭발의 비밀이 밝혀졌습니다. 정구희 기자입니다.
http://www.astronomy.com/news/2017/08/lost-nova-is-found-again
First observed 600 years ago, this binary system is providing vital clues to how novae work.
Published: Wednesday, August 30, 2017
In the tail of Scorpius the Scorpion, a new star appeared briefly nearly 600 years ago. The year was 1437, and the previously unseen star, which flared bright and lasted 14 days before disappearing, was recorded by Korean astrologers at the time. Lost to astronomers hunting for its source since that date, the binary star system that underwent that nova has now been found.
The work, published today in Nature, describes “the first nova that's ever been recovered with certainty based on the Chinese, Korean, and Japanese records of almost 2,500 years,” according to lead author Michael Shara, a curator in the American Museum of Natural History's Department of Astrophysics, in a press release. Rediscovering this nova, which now appears to undergo periodic smaller-scale nova explosions, provides key support for the theory that novae have long life cycles, and can go dormant before ramping up again.
A nova differs from a supernova in that the former is not a catastrophic event that destroys its progenitor star. In a nova system, a white dwarf (the remnant of a star like our Sun) pulls material off a companion star, which is still in the hydrogen-burning phase of its life. This material, mostly hydrogen, piles up slowly over the course of something like 100,000 years, until it reaches a critical point. At that point, the hydrogen envelope suddenly fuses into helium, releasing a huge amount of energy that’s seen as a nova. It’s essentially a giant hydrogen bomb, and the white dwarf can shine several hundred thousand times brighter for days or even months afterward.
In a type Ia supernova, which occurs in similar systems, it’s thought that the white dwarf pulls matter off its companion much more quickly, and reaches a critical mass point that triggers a larger explosion, which does tear the white dwarf apart. Thus, supernovae destroy the stellar remnant that creates them; novae do not, allowing the process of hydrogen buildup to occur again and possibly trigger another nova in the future.
The nova of 1437 has been elusive, with several astronomers including Shara, Richard Stephenson of Durham University, and Mike Bode of Liverpool John Moores University searching for the binary system that caused it.
But recently, after expanding their initial search area, they came across a shell of material: the sign of a classical nova explosion. They even found a bright star near — but not in — the center of the shell.
The team cross-referenced their find with an image of the area taken at the Harvard Observatory station in Peru in 1923, and were able to accurately chart the star’s motion across the sky over time. Based on their calculations, “… we traced it back six centuries, and bingo, there it was, right at the center of our shell. That's the clock, that's what convinced us that it had to be right,” said Shara.
That photographic plate is now part of the Digitizing a Sky Century at Harvard (DASCH) project. And with the addition of other plates from the DASCH project taken in the 1940s, Shara and his team discovered that the nova is now something called a “dwarf nova,” which undergoes periodic small outbursts that are likely due to instabilities in the material as it forms a disk around and accretes onto the white dwarf, rather than the huge explosion of a “classical nova,” like the event it underwent nearly 600 years ago.
This behavior helps to cement the idea that classical novae, dwarf novae, and other objects that show novae-like variability are all different stages of the same type of system. “In the same way that an egg, a caterpillar, a pupa, and a butterfly are all life stages of the same organism, we now have strong support for the idea that these binaries are all the same thing seen in different phases of their lives,” Shara explained.
However, because these systems can evolve and change over hundreds of thousands of years, showing different types of behavior at different times, it’s been difficult to link them together. “We simply haven't been around long enough to see a single complete cycle,” said Shara.
But now, the rediscovery of the 1437 eruption and the ability to trace its evolution over time, astronomers can take a closer, more complete look at that life cycle to approach a better understanding of how systems that may seem different are really all one and the same.
http://
https://www.youtube.com/watch?v=FlJ0zP_CzgA
https://www.youtube.com/watch?v=FlJ0zP_CzgA
http://www.astronomy.com/news/2017/08/lost-nova-is-found-again
JSCh
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U.S.-China mission rushes bomb-grade nuclear fuel out of Africa
By Richard Stone
Aug. 31, 2017 , 9:00 AM
ACCRA AND BEIJING—Dan Peng steps onto a narrow steel frame just above a 6-meter-deep pool, which holds a nuclear reactor about to go critical. Clad in a lab coat with a pocket radiation dosimeter, sweating in the stifling reactor hall here on the outskirts of Ghana's capital, the young nuclear physicist edges out to a tube jutting above the water's surface. He grabs a cord leading out of the tube and reels it up, hand over hand, until a cigar-shaped capsule emerges—a packet of neutron-absorbing cadmium. It's the last of three that were immersed in the pool as a safety measure, to ensure that the reactor's new low-enriched uranium (LEU) core did not achieve a self-sustaining fission reaction—criticality—before the team was ready.
At the edge of the pool, several other physicists and engineers, colleagues of Peng's at the China Institute of Atomic Energy (CIAE) in Beijing, huddle behind a bank of instruments. On one digital display, numbers change in a blur as the neutron count shoots up, then levels off. Now, the only bulwark against criticality is a single control rod piercing the heart of the reactor.
"We're ready," says a smiling Li Yiguo, a CIAE nuclear physicist and leader of a landmark effort in nuclear nonproliferation at the Ghana Research Reactor (GHARR-1). Li asks a colleague to summon dignitaries to mark the culmination of a 10-year odyssey to remove GHARR-1's highly enriched uranium (HEU) fuel—weapons-grade material—and replace it with LEU, which cannot be used for a nuclear bomb without further enrichment.
The operation, which took place in July at the Ghana Atomic Energy Commission in Accra, is a milestone in a dogged effort since the end of the Cold War to remove enriched uranium and plutonium from countries that do not have nuclear weapons. Spearheaded by the United States and the International Atomic Energy Agency (IAEA) in Vienna, the initiative took on added urgency after the 9/11 attacks, out of fear of al-Qaida or another terrorist group laying hands on nuclear materials. Small, HEU-fueled research reactors, including GHARR-1 and four other Chinese-made miniature neutron source reactors (MNSRs) operating in the Middle East and Africa, were a high priority. But reengineering an MNSR's core—a cylindrical array of 350 fuel and dummy pins that is a little larger than a gallon paint can—to run on safer fuel posed unique challenges.
Chinese and U.S. nuclear experts spent a decade plotting out the Ghana operation, sharing expertise and working at each other's labs. "No question, we were able to collaborate very, very well on the MNSR conversion," says Ernest Moniz, CEO of the Nuclear Threat Initiative (NTI), a think tank in Washington, D.C., and former secretary of the U.S. Department of Energy (DOE). The process strengthened a bond that is quietly developing between nuclear scientists in the United States and China. "It's very important for building trust," says Hui Zhang, a nuclear policy analyst at the Belfer Center for Science and International Affairs at Harvard University.
In 1999, relations between Chinese and U.S. nuclear scientists entered a tailspin after the U.S. Congress, in a high-profile report, accused China of stealing nuclear weapons secrets from DOE's national laboratories. China denied the allegations, and U.S. nonproliferation experts cast doubt on them. Nevertheless, the accusations torpedoed a nascent technical exchange program between U.S. and Chinese weapons scientists.
But now, even as the two countries are embroiled in trade disputes and tensions over the South China Sea and North Korea's nuclear program, collaborations between their nuclear scientists are intensifying. Last year, China opened a Center of Excellence (COE) in nuclear security in Beijing that's filled with top-of-the-line instrumentation for combatting nuclear smuggling and terrorism; Chinese and U.S. physicists work together there to hone measures for protecting nuclear facilities and analyzing interdicted nuclear materials. Under the 2015 Iran nuclear deal, U.S. and Chinese scientists are helping counterparts in Iran reconfigure a heavy water reactor in Arak so it can no longer produce significant quantities of plutonium. And the research reactor conversions will continue. Next up is an MNSR in Nigeria in spring 2018, followed by reactors in Iran, Pakistan, and—when conditions permit—Syria.
The MNSR conversions "show real leadership on the part of the Chinese," says David Huizenga, acting deputy administrator for defense nuclear nonproliferation at DOE's National Nuclear Security Administration (NNSA) in Washington, D.C. They are part of a "very important partnership" in nuclear security, he says, in which something unthinkable only a few years ago is taking place: Chinese and U.S. weapons scientists are finding ways to work together.
Con't reading --> U.S.-China mission rushes bomb-grade nuclear fuel out of Africa | Science | AAAS
By Richard Stone
Aug. 31, 2017 , 9:00 AM
ACCRA AND BEIJING—Dan Peng steps onto a narrow steel frame just above a 6-meter-deep pool, which holds a nuclear reactor about to go critical. Clad in a lab coat with a pocket radiation dosimeter, sweating in the stifling reactor hall here on the outskirts of Ghana's capital, the young nuclear physicist edges out to a tube jutting above the water's surface. He grabs a cord leading out of the tube and reels it up, hand over hand, until a cigar-shaped capsule emerges—a packet of neutron-absorbing cadmium. It's the last of three that were immersed in the pool as a safety measure, to ensure that the reactor's new low-enriched uranium (LEU) core did not achieve a self-sustaining fission reaction—criticality—before the team was ready.
At the edge of the pool, several other physicists and engineers, colleagues of Peng's at the China Institute of Atomic Energy (CIAE) in Beijing, huddle behind a bank of instruments. On one digital display, numbers change in a blur as the neutron count shoots up, then levels off. Now, the only bulwark against criticality is a single control rod piercing the heart of the reactor.
"We're ready," says a smiling Li Yiguo, a CIAE nuclear physicist and leader of a landmark effort in nuclear nonproliferation at the Ghana Research Reactor (GHARR-1). Li asks a colleague to summon dignitaries to mark the culmination of a 10-year odyssey to remove GHARR-1's highly enriched uranium (HEU) fuel—weapons-grade material—and replace it with LEU, which cannot be used for a nuclear bomb without further enrichment.
The operation, which took place in July at the Ghana Atomic Energy Commission in Accra, is a milestone in a dogged effort since the end of the Cold War to remove enriched uranium and plutonium from countries that do not have nuclear weapons. Spearheaded by the United States and the International Atomic Energy Agency (IAEA) in Vienna, the initiative took on added urgency after the 9/11 attacks, out of fear of al-Qaida or another terrorist group laying hands on nuclear materials. Small, HEU-fueled research reactors, including GHARR-1 and four other Chinese-made miniature neutron source reactors (MNSRs) operating in the Middle East and Africa, were a high priority. But reengineering an MNSR's core—a cylindrical array of 350 fuel and dummy pins that is a little larger than a gallon paint can—to run on safer fuel posed unique challenges.
Chinese and U.S. nuclear experts spent a decade plotting out the Ghana operation, sharing expertise and working at each other's labs. "No question, we were able to collaborate very, very well on the MNSR conversion," says Ernest Moniz, CEO of the Nuclear Threat Initiative (NTI), a think tank in Washington, D.C., and former secretary of the U.S. Department of Energy (DOE). The process strengthened a bond that is quietly developing between nuclear scientists in the United States and China. "It's very important for building trust," says Hui Zhang, a nuclear policy analyst at the Belfer Center for Science and International Affairs at Harvard University.
In 1999, relations between Chinese and U.S. nuclear scientists entered a tailspin after the U.S. Congress, in a high-profile report, accused China of stealing nuclear weapons secrets from DOE's national laboratories. China denied the allegations, and U.S. nonproliferation experts cast doubt on them. Nevertheless, the accusations torpedoed a nascent technical exchange program between U.S. and Chinese weapons scientists.
But now, even as the two countries are embroiled in trade disputes and tensions over the South China Sea and North Korea's nuclear program, collaborations between their nuclear scientists are intensifying. Last year, China opened a Center of Excellence (COE) in nuclear security in Beijing that's filled with top-of-the-line instrumentation for combatting nuclear smuggling and terrorism; Chinese and U.S. physicists work together there to hone measures for protecting nuclear facilities and analyzing interdicted nuclear materials. Under the 2015 Iran nuclear deal, U.S. and Chinese scientists are helping counterparts in Iran reconfigure a heavy water reactor in Arak so it can no longer produce significant quantities of plutonium. And the research reactor conversions will continue. Next up is an MNSR in Nigeria in spring 2018, followed by reactors in Iran, Pakistan, and—when conditions permit—Syria.
The MNSR conversions "show real leadership on the part of the Chinese," says David Huizenga, acting deputy administrator for defense nuclear nonproliferation at DOE's National Nuclear Security Administration (NNSA) in Washington, D.C. They are part of a "very important partnership" in nuclear security, he says, in which something unthinkable only a few years ago is taking place: Chinese and U.S. weapons scientists are finding ways to work together.
Con't reading --> U.S.-China mission rushes bomb-grade nuclear fuel out of Africa | Science | AAAS
Martian2
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China's Comac is the designer of the C919 narrow-body jet. The capacity of the commercial jet is 190 passengers.
Comac is also the designer of the earlier ARJ-21 regional jet. The ARJ-21 has a smaller passenger capacity of 90.
Comac spent eight years (2008-2016) testing the ARJ-21. The experience-gained was very valuable and is probably accelerating the test-schedule for the larger C919. After all, the basic test procedures are similar (such as certification for cold/hot weather, night-time, altitude, etc.).
Last week, Comac displayed an exact-replica flight simulator of the C919 to the public. The following photographs offer an exciting glimpse into the C919 high-tech cockpit controls. China's C919 airliner was built to compete against the Boeing 737 and the Airbus A320.
----------
C919 flight simulator debuts at Shanghai expo | China Daily
Comac is also the designer of the earlier ARJ-21 regional jet. The ARJ-21 has a smaller passenger capacity of 90.
Comac spent eight years (2008-2016) testing the ARJ-21. The experience-gained was very valuable and is probably accelerating the test-schedule for the larger C919. After all, the basic test procedures are similar (such as certification for cold/hot weather, night-time, altitude, etc.).
Last week, Comac displayed an exact-replica flight simulator of the C919 to the public. The following photographs offer an exciting glimpse into the C919 high-tech cockpit controls. China's C919 airliner was built to compete against the Boeing 737 and the Airbus A320.
----------
C919 flight simulator debuts at Shanghai expo | China Daily
JSCh
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China produces its first neutron beams
By ZHANG ZHIHAO | China Daily | Updated: 2017-09-02 06:46
China has become the latest country to create neutron beams－which can examine subatomic materials without damaging their structure－an advance expected to lead to new discoveries in material science, clean energy and medicine.
The beams were first produced on Aug 28 at the China Spallation Neutron Source in Dongguan, Guangdong province, making China the fourth country in the world, after the United States, United Kingdom and Japan, to have a neutron beam source.
"This is a major milestone for Chinese scientists. The lab will help us solve some of the nation's most difficult scientific issues," said Chen Hesheng, an academician of the Chinese Academy of Sciences and the manager of the project.
"It will also help the Guangdong-Hong Kong-Macao Greater Bay Area to upgrade its industries and support their high-end scientific research and development," Chen said.
The China Spallation Neutron Source cost 1.87 billion yuan ($280 million) and took around six and a half years to build. It will be fully operational next year and Chinese scientists from more than 70 projects and 22 universities have applied to use it. The facility would also be open to foreign researchers, he said.
Neutrons and protons are found at the nucleus, or the core of an atom－the basic building block of materials. While protons have a positive charge, neutrons have no electric charge, and have strong penetrative capability.
As a result, unlike X-rays, whose ionized radiation can rip through the atomic structures of biomaterials like proteins, neutron rays can just pass through the material without damaging the structures, Chen said.
However, some neutrons will hit the atomic nucleus in the material and "bounce" harmlessly away at an angle in a phenomenon called neutron scattering, hence creating the "spallation". Using detectors, scientists can count these scattered neutrons, measure their energies and the angles at which they scatter, and map their final positions.
This way, scientists can glean details about the nature of the examined materials－from its atomic arrangement to movements.
"This will help scientists discover new chemical mechanisms for producing clean energy, new material for more powerful electronics, or create stronger and more durable material for engines," Chen said.
Another promising application is creating new therapies to treat tumors that are difficult to operate on by hand, such as brain tumors, said Fu Shinian, a researcher at the academy's Institute of High Energy Physics.
The Boron Neutron Capture Therapy takes advantage of boron's properties to accurately latch onto cancer cells. Then doctors can shine neutron beams at the tumor, triggering the boron to kill the cancer cells while leaving surrounding cells intact, Fu said.
Despite these promising applications, creating neutron beams is no easy task. In China's neutron source, scientists have to accelerate a group of protons close to the speed of light, use them to smash into a target tungsten block, and knock the neutrons out of the target's atomic nucleus.
Then these neutrons are "sucked" into various branches and channeled into different lab equipment for research, said Chen. All of the equipment used to generate the neutron beams is more than a dozen meters underground, trapping the tiny amount of harmful radiation created in the process.
China's neutron source will be free to the public, only collecting a small fee from companies with special needs.
By ZHANG ZHIHAO | China Daily | Updated: 2017-09-02 06:46
China has become the latest country to create neutron beams－which can examine subatomic materials without damaging their structure－an advance expected to lead to new discoveries in material science, clean energy and medicine.
The beams were first produced on Aug 28 at the China Spallation Neutron Source in Dongguan, Guangdong province, making China the fourth country in the world, after the United States, United Kingdom and Japan, to have a neutron beam source.
"This is a major milestone for Chinese scientists. The lab will help us solve some of the nation's most difficult scientific issues," said Chen Hesheng, an academician of the Chinese Academy of Sciences and the manager of the project.
"It will also help the Guangdong-Hong Kong-Macao Greater Bay Area to upgrade its industries and support their high-end scientific research and development," Chen said.
The China Spallation Neutron Source cost 1.87 billion yuan ($280 million) and took around six and a half years to build. It will be fully operational next year and Chinese scientists from more than 70 projects and 22 universities have applied to use it. The facility would also be open to foreign researchers, he said.
Neutrons and protons are found at the nucleus, or the core of an atom－the basic building block of materials. While protons have a positive charge, neutrons have no electric charge, and have strong penetrative capability.
As a result, unlike X-rays, whose ionized radiation can rip through the atomic structures of biomaterials like proteins, neutron rays can just pass through the material without damaging the structures, Chen said.
However, some neutrons will hit the atomic nucleus in the material and "bounce" harmlessly away at an angle in a phenomenon called neutron scattering, hence creating the "spallation". Using detectors, scientists can count these scattered neutrons, measure their energies and the angles at which they scatter, and map their final positions.
This way, scientists can glean details about the nature of the examined materials－from its atomic arrangement to movements.
"This will help scientists discover new chemical mechanisms for producing clean energy, new material for more powerful electronics, or create stronger and more durable material for engines," Chen said.
Another promising application is creating new therapies to treat tumors that are difficult to operate on by hand, such as brain tumors, said Fu Shinian, a researcher at the academy's Institute of High Energy Physics.
The Boron Neutron Capture Therapy takes advantage of boron's properties to accurately latch onto cancer cells. Then doctors can shine neutron beams at the tumor, triggering the boron to kill the cancer cells while leaving surrounding cells intact, Fu said.
Despite these promising applications, creating neutron beams is no easy task. In China's neutron source, scientists have to accelerate a group of protons close to the speed of light, use them to smash into a target tungsten block, and knock the neutrons out of the target's atomic nucleus.
Then these neutrons are "sucked" into various branches and channeled into different lab equipment for research, said Chen. All of the equipment used to generate the neutron beams is more than a dozen meters underground, trapping the tiny amount of harmful radiation created in the process.
China's neutron source will be free to the public, only collecting a small fee from companies with special needs.
Last edited:
JSCh
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Nanoscience making China global leader
Source: Xinhua | 00:01 UTC+8 September 4, 2017
Russian-British physicist Kostya Novoselov, winner of 2010 Nobel Prize in Physics for his work on graphene with Andre Geim, speaks at ChinaNANO 2017 in Beijing. — Xinhua
MOBILE phones, computers, cosmetics, bicycles... nanoscience is hiding in so many everyday items, wielding a huge influence on our lives at a microscale level.
Scientists and engineers from around the world exchanged new findings and perceptions on nanotechnology at the recent 7th International Conference on Nanoscience and Technology (ChinaNANO 2017) in Beijing last week.
China has become a nanotechnology powerhouse, according to a report released at the conference. China’s applied nanoscience research and the industrialization of nanotechnology have been developing steadily, with the number of nano-related patent applications ranking among the top in the world.
The report was co-produced by Springer Nature, National Center for Nanoscience and Technology (NCNST) and the National Science Library of the Chinese Academy of Sciences (CAS).
According to Bai Chunli, president of CAS, China faces new opportunities for nanoscience research and development as it builds the NCNST and globally influential national science centers.
“We will strengthen the strategic landscape and top-down design for developing nanoscience, which will contribute greatly to the country’s economy and society,” said Bai.
Nanoscience can be defined as the study of the interaction, composition, properties and manufacturing methods of materials at a nanometer scale.
At such tiny scales, the physical, chemical and biological properties of materials are different from those at larger scales — often profoundly so.
For example, alloys that are weak or brittle become strong and ductile; compounds that are chemically inert become powerful catalysts.
It is estimated that there are more than 1,600 nanotechnology-based consumer products on the market, including lightweight but sturdy tennis rackets, bicycles, suitcases, automobile parts and rechargeable batteries.
Nanomaterials are used in hairdryers or straighteners to make them lighter and more durable. The secret of how sunscreens protect skin from sunburn lies in the nanometer-scale titanium dioxide or zinc oxide they contain.
In 2016, the world’s first one-nanometer transistor was created. It was made from carbon nanotubes and molybdenum disulphide, rather than silicon. Carbon nanotubes or silver nanowires enable touch screens on computers and televisions to be flexible, said Zhu Xing, chief scientist at the NCNST.
Nanotechnology is also having an increasing impact on healthcare, with progress in drug delivery, biomaterials, imaging, diagnostics, active implants and other therapeutic applications.
The biggest current concern is the health threats of nanoparticles, which can easily enter body via airways or skin. Construction workers exposed to nanopollutants face increased health risks.
In response to these concerns, the Chinese government has invested in nanosafety research since 2001, with around 7 percent of the nanotechnology research budget going to research into the environmental, health and safety implications of nanotechnology, said Zhu.
Since 2007, the average compound annual growth rate of China’s most cited nanoscience papers was 22 percent — three times the global rate, the report stated.
In terms of the number of nano-related patent applications, China has reached 209,344 over the past 20 years, accounting for 45 percent of the world’s total.
In 2003, CAS and the Ministry of Education co-established the NCNST. Key to the NCNST’s success has been the involvement of three of China’s top research institutions — Tsinghua University, Peking University and CAS, said Liu Minghua, director of the NCNST.
Liu said that due to robust funding, a growing number of Chinese scientists have been attracted to research of nanomaterials. Additionally, more foreign-trained Chinese researchers have returned to China under favorable policies.
Energy nanotechnology and catalytic nanomaterials are the top two fields in which China has made remarkable achievements.
Faced with mounting public pressure to tackle deteriorating environmental problems, China is putting great effort into the research and development of new energy, as well as efficient energy and environmental protection technology.
This has made energy nanotechnology a promising area, leading Chinese researchers to research batteries and energy storage and conversion, Liu said.
Catalytic nanomaterials research is considered China’s most promising area of nanoscience. Nanostructure-based catalysts can speed up chemical reactions and could be useful in chemical industries and oil refining, experts said.
Bai said both challenges and opportunities await China. More breakthroughs in basic nanoscience research need to be made, and the gap between basic research and application should be closed.
CAS will foster more young scientists who can innovate, accelerate the building of value chains, and foster broad and efficient international collaboration, Bai said.
“Through our joint efforts, we expect to apply nanotechnology to various sectors that will benefit the people and help China to be a global leader in science and technology,” Bai said.
Source: Xinhua | 00:01 UTC+8 September 4, 2017
MOBILE phones, computers, cosmetics, bicycles... nanoscience is hiding in so many everyday items, wielding a huge influence on our lives at a microscale level.
Scientists and engineers from around the world exchanged new findings and perceptions on nanotechnology at the recent 7th International Conference on Nanoscience and Technology (ChinaNANO 2017) in Beijing last week.
China has become a nanotechnology powerhouse, according to a report released at the conference. China’s applied nanoscience research and the industrialization of nanotechnology have been developing steadily, with the number of nano-related patent applications ranking among the top in the world.
The report was co-produced by Springer Nature, National Center for Nanoscience and Technology (NCNST) and the National Science Library of the Chinese Academy of Sciences (CAS).
According to Bai Chunli, president of CAS, China faces new opportunities for nanoscience research and development as it builds the NCNST and globally influential national science centers.
“We will strengthen the strategic landscape and top-down design for developing nanoscience, which will contribute greatly to the country’s economy and society,” said Bai.
Nanoscience can be defined as the study of the interaction, composition, properties and manufacturing methods of materials at a nanometer scale.
At such tiny scales, the physical, chemical and biological properties of materials are different from those at larger scales — often profoundly so.
For example, alloys that are weak or brittle become strong and ductile; compounds that are chemically inert become powerful catalysts.
It is estimated that there are more than 1,600 nanotechnology-based consumer products on the market, including lightweight but sturdy tennis rackets, bicycles, suitcases, automobile parts and rechargeable batteries.
Nanomaterials are used in hairdryers or straighteners to make them lighter and more durable. The secret of how sunscreens protect skin from sunburn lies in the nanometer-scale titanium dioxide or zinc oxide they contain.
In 2016, the world’s first one-nanometer transistor was created. It was made from carbon nanotubes and molybdenum disulphide, rather than silicon. Carbon nanotubes or silver nanowires enable touch screens on computers and televisions to be flexible, said Zhu Xing, chief scientist at the NCNST.
Nanotechnology is also having an increasing impact on healthcare, with progress in drug delivery, biomaterials, imaging, diagnostics, active implants and other therapeutic applications.
The biggest current concern is the health threats of nanoparticles, which can easily enter body via airways or skin. Construction workers exposed to nanopollutants face increased health risks.
In response to these concerns, the Chinese government has invested in nanosafety research since 2001, with around 7 percent of the nanotechnology research budget going to research into the environmental, health and safety implications of nanotechnology, said Zhu.
Since 2007, the average compound annual growth rate of China’s most cited nanoscience papers was 22 percent — three times the global rate, the report stated.
In terms of the number of nano-related patent applications, China has reached 209,344 over the past 20 years, accounting for 45 percent of the world’s total.
In 2003, CAS and the Ministry of Education co-established the NCNST. Key to the NCNST’s success has been the involvement of three of China’s top research institutions — Tsinghua University, Peking University and CAS, said Liu Minghua, director of the NCNST.
Liu said that due to robust funding, a growing number of Chinese scientists have been attracted to research of nanomaterials. Additionally, more foreign-trained Chinese researchers have returned to China under favorable policies.
Energy nanotechnology and catalytic nanomaterials are the top two fields in which China has made remarkable achievements.
Faced with mounting public pressure to tackle deteriorating environmental problems, China is putting great effort into the research and development of new energy, as well as efficient energy and environmental protection technology.
This has made energy nanotechnology a promising area, leading Chinese researchers to research batteries and energy storage and conversion, Liu said.
Catalytic nanomaterials research is considered China’s most promising area of nanoscience. Nanostructure-based catalysts can speed up chemical reactions and could be useful in chemical industries and oil refining, experts said.
Bai said both challenges and opportunities await China. More breakthroughs in basic nanoscience research need to be made, and the gap between basic research and application should be closed.
CAS will foster more young scientists who can innovate, accelerate the building of value chains, and foster broad and efficient international collaboration, Bai said.
“Through our joint efforts, we expect to apply nanotechnology to various sectors that will benefit the people and help China to be a global leader in science and technology,” Bai said.
JSCh
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Two distant hypervelocity stars discovered by Chinese astronomers
September 4, 2017 by Tomasz Nowakowski
LAMOST spectra of LAMOST-HVS1 (top), LAMOST-HVS2 (middle) and LAMOST-HVS3 (bottom). The inset in each panel shows the enlarged normalized blue-arm spectrum. Credit: Huang et al., 2017.
(Phys.org)—A group of Chinese astronomers led by Yang Huang of the Yunnan University in Kunming, China, has detected two new unbound hypervelocity stars located over 70,000 light years away. The discovery, described in a paper published Aug. 29 on the arXiv pre-print server, could help scientists better understand the nature of these rare, peculiar stars.
Hypervelocity stars (HVSs) are rare objects with velocities so great that they exceed the escape velocity of the galaxy. Astronomers believe that they originate near the center of the Milky Way galaxy by dynamical interactions between binary stars and the central massive black hole. While ordinary stars have velocities around 100 km/s, the velocities of HVSs can reach even 1,000 km/s.
Although scientists estimate that approximately 1,000 HVSs exist in the Milky Way, only about 20 such stars have been identified so far. Given that these objects travel large distances across our galaxy, they could serve as powerful tracers to probe the mass distribution in the Milky Way, providing crucial information about the shape of the galactic dark matter halo. Therefore, finding new HVSs could help us build a valuable database of such tracers.
With this aim in mind, Huang's team have analyzed the available data provided by the LAMOST spectroscopic surveys. The surveys, utilizing the Large Sky Area Multi-Object Fibre Spectroscopic Telescope (LAMOST) in China, investigate the structure and evolution of our galaxy, and have already located one hypervelocity star.
Now, the Chinese astronomers report the finding of two new HVSs in the latest data release from the LAMOST surveys. The researchers found two new unbound hypervelocity stars, designated LAMOST-HVS2 and LAMOST-HVS3. They also re-discovered LAMOST-HSV1 – the first HVS spotted by LAMOST in 2014.
According to the study, LAMOST-HVS2 has a spectral type B2V, mass of about 7.3 solar masses and an effective temperature of 20,600 K. The star, located about 72,500 light years away from the Earth, has a heliocentric radial velocity of 341.1 km/s, which corresponds to a galactic rest-frame radial velocity of 502.33 km/s.
With an effective temperature of 14,000 K, LAMOST-HVS3 is nearly four times as massive as the sun and has a spectral type B7V. The star's heliocentric radial velocity was found to be 361.38 km/s, while its galactic rest-frame radial velocity equals 408.33 km/s. LAMOST-HVS3 is located some 72,760 light years away from our planet.
The researchers assume that the two newly discovered HSVs and the one found earlier may originate from the galactic center and their progenitors are spatially associated with young stellar structures near the center of the Milky Way. However, more studies are needed to confirm this hypothesis. Therefore, the team hopes that the upcoming new data release from ESA's Gaia satellite could shed some light on this problem.
"Finally, accurate proper motion measurements are required in order to better constrain the origin of the three HVSs discovered with LAMOST. The current measurements have uncertainties (systematic plus random) too large to make a conclusive analysis. Fortunately, all the three stars are quite bright and the upcoming Gaia data release should solve this problem," the authors concluded.
More information: Discovery of two new hypervelocity stars from the LAMOST spectroscopic surveys, arXiv:1708.08602 [astro-ph.GA] arxiv.org/abs/1708.08602
https://phys.org/news/2017-09-distant-hypervelocity-stars-chinese-astronomers.html
September 4, 2017 by Tomasz Nowakowski
LAMOST spectra of LAMOST-HVS1 (top), LAMOST-HVS2 (middle) and LAMOST-HVS3 (bottom). The inset in each panel shows the enlarged normalized blue-arm spectrum. Credit: Huang et al., 2017.
(Phys.org)—A group of Chinese astronomers led by Yang Huang of the Yunnan University in Kunming, China, has detected two new unbound hypervelocity stars located over 70,000 light years away. The discovery, described in a paper published Aug. 29 on the arXiv pre-print server, could help scientists better understand the nature of these rare, peculiar stars.
Hypervelocity stars (HVSs) are rare objects with velocities so great that they exceed the escape velocity of the galaxy. Astronomers believe that they originate near the center of the Milky Way galaxy by dynamical interactions between binary stars and the central massive black hole. While ordinary stars have velocities around 100 km/s, the velocities of HVSs can reach even 1,000 km/s.
Although scientists estimate that approximately 1,000 HVSs exist in the Milky Way, only about 20 such stars have been identified so far. Given that these objects travel large distances across our galaxy, they could serve as powerful tracers to probe the mass distribution in the Milky Way, providing crucial information about the shape of the galactic dark matter halo. Therefore, finding new HVSs could help us build a valuable database of such tracers.
With this aim in mind, Huang's team have analyzed the available data provided by the LAMOST spectroscopic surveys. The surveys, utilizing the Large Sky Area Multi-Object Fibre Spectroscopic Telescope (LAMOST) in China, investigate the structure and evolution of our galaxy, and have already located one hypervelocity star.
Now, the Chinese astronomers report the finding of two new HVSs in the latest data release from the LAMOST surveys. The researchers found two new unbound hypervelocity stars, designated LAMOST-HVS2 and LAMOST-HVS3. They also re-discovered LAMOST-HSV1 – the first HVS spotted by LAMOST in 2014.
According to the study, LAMOST-HVS2 has a spectral type B2V, mass of about 7.3 solar masses and an effective temperature of 20,600 K. The star, located about 72,500 light years away from the Earth, has a heliocentric radial velocity of 341.1 km/s, which corresponds to a galactic rest-frame radial velocity of 502.33 km/s.
With an effective temperature of 14,000 K, LAMOST-HVS3 is nearly four times as massive as the sun and has a spectral type B7V. The star's heliocentric radial velocity was found to be 361.38 km/s, while its galactic rest-frame radial velocity equals 408.33 km/s. LAMOST-HVS3 is located some 72,760 light years away from our planet.
The researchers assume that the two newly discovered HSVs and the one found earlier may originate from the galactic center and their progenitors are spatially associated with young stellar structures near the center of the Milky Way. However, more studies are needed to confirm this hypothesis. Therefore, the team hopes that the upcoming new data release from ESA's Gaia satellite could shed some light on this problem.
"Finally, accurate proper motion measurements are required in order to better constrain the origin of the three HVSs discovered with LAMOST. The current measurements have uncertainties (systematic plus random) too large to make a conclusive analysis. Fortunately, all the three stars are quite bright and the upcoming Gaia data release should solve this problem," the authors concluded.
More information: Discovery of two new hypervelocity stars from the LAMOST spectroscopic surveys, arXiv:1708.08602 [astro-ph.GA] arxiv.org/abs/1708.08602
Abstract
We report the discovery of two new unbound hypervelocity stars (HVSs) from the LAMOST spectroscopic surveys. They are respectively a B2V type star of ~ 7 M⊙ with a Galactic rest-frame radial velocity of 502 km/s at a Galactocentric radius of ~ 21 kpc and a B7V type star of ~ 4 M⊙ with a Galactic rest-frame radial velocity of 408 km/s at a Galactocentric radius of ~ 30 kpc. The origins of the two HVSs are not clear given their currently poorly measured proper motions. However, the future data releases of Gaia should provide proper motion measurements accurate enough to solve this problem. The ongoing LAMOST spectroscopic surveys are expected to yield more HVSs to form a statistical sample, providing vital constraint on understanding the nature of HVSs and their ejection mechanisms.
We report the discovery of two new unbound hypervelocity stars (HVSs) from the LAMOST spectroscopic surveys. They are respectively a B2V type star of ~ 7 M⊙ with a Galactic rest-frame radial velocity of 502 km/s at a Galactocentric radius of ~ 21 kpc and a B7V type star of ~ 4 M⊙ with a Galactic rest-frame radial velocity of 408 km/s at a Galactocentric radius of ~ 30 kpc. The origins of the two HVSs are not clear given their currently poorly measured proper motions. However, the future data releases of Gaia should provide proper motion measurements accurate enough to solve this problem. The ongoing LAMOST spectroscopic surveys are expected to yield more HVSs to form a statistical sample, providing vital constraint on understanding the nature of HVSs and their ejection mechanisms.
https://phys.org/news/2017-09-distant-hypervelocity-stars-chinese-astronomers.html
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JSCh
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Raycus fiber lasers exemplify nation's Made in China plan
By Zheng Xin and Zou Shuo | China Daily | Updated: 2017-09-06 07:54
Yan Dapeng, a leading expert in the development of fiber lasers, was visiting Wuhan in 2006 when he found out the fiber laser products he had helped create in the United States were sold to China at high, nonnegotiable prices, with poor after-sales service.
One year later, at the age of 51, Yan resigned from his US job, came back to China and partnered with a domestic company to found Raycus, which has developed into a leading developer and manufacturer of high-powered fiber laser and core components in China, breaking the American monopoly in the sector.
In 2013, Raycus succeeded in developing China's first 10 kW fiber laser－making China the second country to master the technology in the world. Last year, a 20 kW fiber laser produced by Raycus was unveiled at the laser technology and industry development forum held in Wuhan, Central China's Hubei province. That product is expected to enter mass production by 2018, according to the company.
Fiber laser, which releases laser energy through a fiber as thin as a human hair, has been widely applied in aerospace, shipbuilding, airplane and auto manufacturing, as well as 3D printing. It is an indispensable component of precision machining.
Compared with carbon dioxide laser, fiber lasers feature three times faster emitting speed, 20 percent higher energy conversion efficiency, four times less power consumption, with no noise or pollution emitted.
Yan said fiber laser industry is of strategic significance and an important industry in military-civilian integration.
The United States still embargoes the export of high-power fiber lasers of more than 1,000 W to China. However, since Raycus has successfully produced fiber lasers with that much or more power, the embargo thus makes no sense, he said.
China's breakthrough in high-power fiber laser is also proving to be lucrative.
According to Yan, the successful development of the 10 kW fiber laser has lowered the price of imported fiber laser from five million yuan ($760,000) to a little more than three million yuan. As the country realizes production of 20 kW fiber laser, the price of imported ones will decrease by 40 percent.
China has made great efforts to upgrade its manufacturing industry into a more intelligent one. In 2015, the country put forward the "Made in China 2025" initiative, which seeks to transform itself from a manufacturing giant into a global high-tech manufacturing power.
Under the initiative, the Chinese government allocated 5.2 billion yuan to promote 133 key projects including bullet trains, 3D printing, construction machinery and electric vehicles in 25 provinces and autonomous regions last year.
However, China still lags behind other countries in fiber laser technology, said Wang Pu, a professor at the Institute of Laser Engineering of Beijing University of Technology.
By Zheng Xin and Zou Shuo | China Daily | Updated: 2017-09-06 07:54
Yan Dapeng, a leading expert in the development of fiber lasers, was visiting Wuhan in 2006 when he found out the fiber laser products he had helped create in the United States were sold to China at high, nonnegotiable prices, with poor after-sales service.
One year later, at the age of 51, Yan resigned from his US job, came back to China and partnered with a domestic company to found Raycus, which has developed into a leading developer and manufacturer of high-powered fiber laser and core components in China, breaking the American monopoly in the sector.
In 2013, Raycus succeeded in developing China's first 10 kW fiber laser－making China the second country to master the technology in the world. Last year, a 20 kW fiber laser produced by Raycus was unveiled at the laser technology and industry development forum held in Wuhan, Central China's Hubei province. That product is expected to enter mass production by 2018, according to the company.
Fiber laser, which releases laser energy through a fiber as thin as a human hair, has been widely applied in aerospace, shipbuilding, airplane and auto manufacturing, as well as 3D printing. It is an indispensable component of precision machining.
Compared with carbon dioxide laser, fiber lasers feature three times faster emitting speed, 20 percent higher energy conversion efficiency, four times less power consumption, with no noise or pollution emitted.
Yan said fiber laser industry is of strategic significance and an important industry in military-civilian integration.
The United States still embargoes the export of high-power fiber lasers of more than 1,000 W to China. However, since Raycus has successfully produced fiber lasers with that much or more power, the embargo thus makes no sense, he said.
China's breakthrough in high-power fiber laser is also proving to be lucrative.
According to Yan, the successful development of the 10 kW fiber laser has lowered the price of imported fiber laser from five million yuan ($760,000) to a little more than three million yuan. As the country realizes production of 20 kW fiber laser, the price of imported ones will decrease by 40 percent.
China has made great efforts to upgrade its manufacturing industry into a more intelligent one. In 2015, the country put forward the "Made in China 2025" initiative, which seeks to transform itself from a manufacturing giant into a global high-tech manufacturing power.
Under the initiative, the Chinese government allocated 5.2 billion yuan to promote 133 key projects including bullet trains, 3D printing, construction machinery and electric vehicles in 25 provinces and autonomous regions last year.
However, China still lags behind other countries in fiber laser technology, said Wang Pu, a professor at the Institute of Laser Engineering of Beijing University of Technology.
JSCh
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06 September 2017
Light-Based Method Improves Practicality and Quality of Remote Wind Measurements
Innovative technology could aid hurricane forecasting, aircraft safety and wind energy generation
WASHINGTON —Researchers have developed a new remote sensing instrument based on light detection and ranging (LIDAR) that could offer a simple and robust way to accurately measure wind speed. The detailed, real-time wind measurements could help scientists to better understand how hurricanes form and provide information that meteorologists can use to pinpoint landfall earlier, giving people more time to prepare and evacuate.
“As hurricane Harvey approached the U.S., hurricane hunters flew directly into the storm and dropped sensors to measure wind speed,” said Xiankang Dou, leader of the research team at the University of Science and Technology of China (USTC). “Our Doppler LIDAR instrument can be used from a plane to remotely measure a hurricane’s wind with high spatial and temporal resolutions. In the future, it could even make these measurements from aboard satellites.”
Wind measurements are also crucial for determining safe flying conditions, understanding how pollution moves through the air and efficiently operating wind turbines. Existing high-accuracy wind measurement technologies can be expensive and difficult to operate, leading to gaps in the application of these technologies in situations where they are most useful.
Mingjia Shangguan and Haiyun Xia from the University of Science and Technology of China were part of a research team who developed a new Doppler LIDAR system for accurately measuring the wind. It features a greatly simplified optical setup that makes it robust and stable enough to use in harsh environments such as aboard aircraft or satellites. Image Credit: Quantum LIDAR Laboratory.
“We demonstrated a Doppler wind LIDAR with a simplified optical layout that also substantially enhances the system stability,” said Dou. “Although specialists are typically needed to operate and maintain a sophisticated Doppler LIDAR, we are confident we can develop our approach into a system that will be as easy to use as a smartphone.”
In The Optical Society (OSA) journal Optics Letters, the researchers demonstrated their Doppler wind LIDAR system’s ability to measure horizontal wind speed with high accuracy and showed that the system remained stable throughout a 10-day test period. The researchers say that the stability and accuracy of this new system represents a substantial improvement compared to previously developed direct detection Doppler wind LIDARs.
One important application of LIDAR is in aeronautics, where it can be used on aircrafts or from a ground station to remotely measure air motion. With a vertical spatial resolution of 10 meters, the new system could measure small-scale wind phenomena such as wind shear and the wake turbulence created by an aircraft. A better understanding of these phenomena could improve flight safety and also increase airport capacity by optimizing the separation between aircraft during takeoff and landing.
Using light to measure wind
LIDAR is a remote sensing method that has been used to create high-resolution maps, scan the bottom of the ocean floor and to guide driverless cars. For measuring wind, a LIDAR system emits a laser pulse that propagates through the atmosphere where it interacts with molecules and aerosols. A small amount of the light scatters back towards the LIDAR instrument, where it is collected by a telescope. When wind causes air to move, this causes a Doppler shift that can be detected by the device.
The researchers designed a dual frequency direct detection Doppler wind LIDAR that used a laser emitting 1.5-micron light. Because this wavelength is commonly used in optical communications networks, they were able to build the system using commercially available fiber-optic components, each combining several light-controlling components into a single device. The all fiber construction of the LiDAR system is therefore robust against vibrations and rough operation handling.
Compared to previously developed systems, the new simplified design makes it much easier to configure and align each component, increases stability and lowers the amount of light lost within the system. The new system also requires no calibration after it is initialized and requires no special eye protection.
“For LIDAR systems that will be operated full-time in the field, eye safety is an important consideration,” said Haiyun Xia, the principle investigator of the Quantum Lidar Laboratory at USTC. “Fortunately, the 1.5-micron laser we used exhibits the highest permissible exposure for eye safety in the wavelength range from 0.3 to 10 microns.”
The 1.5-micron wavelength is also ideal for atmospheric wind sensing from satellites because, compared to UV and visible wavelengths, it shows less susceptibility to atmospheric disturbance and optical contamination from the sun and other sources. Satellite-based wind measurements are used for weather forecasts and meteorological studies. “Space-borne Doppler wind LIDAR is now regarded as the most promising way to meet the need for global wind data requirements and to fill gaps in the wind data provided by other methods,” said Xia.
Upgraded optical components
The optical setup for the new Doppler wind LIDAR contains just one laser source, one detector and a single-channel Fabry-Perot interferometer that converts the Doppler shift into photon number variations of the backscatter signals. Using a Fabry-Perot interferometer made of optical fibers rather than one consisting of many individual optical components made the system robust and stable enough to use in harsh environments such as aboard aircraft or satellites.
The new system also includes one of the fastest detectors available for single photon counting, a superconducting nanowire single photon detector (SNSPD). This detector improved the LIDAR’s performance compared to the InGaAs avalanche photodiodes typically used to detect 1.5-micron light.
“The high detection efficiency and low dark count rate of the SNSPD means that the weak signal from the backscattered light can be detected with a high signal-to-noise ratio,” said Xia. “Another attractive feature of the SNSPD is its high maximum count rate, which helps avoid detector saturation.”
The researchers tested their system by first examining its stability after calibration. Overall, the system’s measurements varied by less than 0.2 meters per second over 10 days in the lab. They then tested the system outdoors and compared its horizontal wind measurements with measurements from an ultrasonic wind sensor, a non-remote system for measuring wind. On average, the LIDAR measurements were within 0.1 meters per second and 1 degrees for wind speed and direction, respectively.
The researchers are now working to improve the spatial resolution of the Doppler wind LIDAR system and want to make it even more practical to use in the field. They have also founded a company to further develop the system and plan to have a commercial version available next year.
Paper: M. Shangguan, H. Xia, C. Wang, J. Qiu, S. Lin, X. Dou, Q. Zhang, J.-W. Pan, “Dual-frequency Doppler LIDAR for wind detection with superconducting nanowire single-photon detector,” Opt. Lett., Volume 42, Issue 18, 3541-3544 (2017).
DOI: 10.1364/OL.42.003541
Light-Based Method Improves Practicality and Quality of Remote Wind Measurements | News Releases | The Optical Society
Light-Based Method Improves Practicality and Quality of Remote Wind Measurements
Innovative technology could aid hurricane forecasting, aircraft safety and wind energy generation
WASHINGTON —Researchers have developed a new remote sensing instrument based on light detection and ranging (LIDAR) that could offer a simple and robust way to accurately measure wind speed. The detailed, real-time wind measurements could help scientists to better understand how hurricanes form and provide information that meteorologists can use to pinpoint landfall earlier, giving people more time to prepare and evacuate.
“As hurricane Harvey approached the U.S., hurricane hunters flew directly into the storm and dropped sensors to measure wind speed,” said Xiankang Dou, leader of the research team at the University of Science and Technology of China (USTC). “Our Doppler LIDAR instrument can be used from a plane to remotely measure a hurricane’s wind with high spatial and temporal resolutions. In the future, it could even make these measurements from aboard satellites.”
Wind measurements are also crucial for determining safe flying conditions, understanding how pollution moves through the air and efficiently operating wind turbines. Existing high-accuracy wind measurement technologies can be expensive and difficult to operate, leading to gaps in the application of these technologies in situations where they are most useful.
“We demonstrated a Doppler wind LIDAR with a simplified optical layout that also substantially enhances the system stability,” said Dou. “Although specialists are typically needed to operate and maintain a sophisticated Doppler LIDAR, we are confident we can develop our approach into a system that will be as easy to use as a smartphone.”
In The Optical Society (OSA) journal Optics Letters, the researchers demonstrated their Doppler wind LIDAR system’s ability to measure horizontal wind speed with high accuracy and showed that the system remained stable throughout a 10-day test period. The researchers say that the stability and accuracy of this new system represents a substantial improvement compared to previously developed direct detection Doppler wind LIDARs.
One important application of LIDAR is in aeronautics, where it can be used on aircrafts or from a ground station to remotely measure air motion. With a vertical spatial resolution of 10 meters, the new system could measure small-scale wind phenomena such as wind shear and the wake turbulence created by an aircraft. A better understanding of these phenomena could improve flight safety and also increase airport capacity by optimizing the separation between aircraft during takeoff and landing.
Using light to measure wind
LIDAR is a remote sensing method that has been used to create high-resolution maps, scan the bottom of the ocean floor and to guide driverless cars. For measuring wind, a LIDAR system emits a laser pulse that propagates through the atmosphere where it interacts with molecules and aerosols. A small amount of the light scatters back towards the LIDAR instrument, where it is collected by a telescope. When wind causes air to move, this causes a Doppler shift that can be detected by the device.
The researchers designed a dual frequency direct detection Doppler wind LIDAR that used a laser emitting 1.5-micron light. Because this wavelength is commonly used in optical communications networks, they were able to build the system using commercially available fiber-optic components, each combining several light-controlling components into a single device. The all fiber construction of the LiDAR system is therefore robust against vibrations and rough operation handling.
Compared to previously developed systems, the new simplified design makes it much easier to configure and align each component, increases stability and lowers the amount of light lost within the system. The new system also requires no calibration after it is initialized and requires no special eye protection.
“For LIDAR systems that will be operated full-time in the field, eye safety is an important consideration,” said Haiyun Xia, the principle investigator of the Quantum Lidar Laboratory at USTC. “Fortunately, the 1.5-micron laser we used exhibits the highest permissible exposure for eye safety in the wavelength range from 0.3 to 10 microns.”
The 1.5-micron wavelength is also ideal for atmospheric wind sensing from satellites because, compared to UV and visible wavelengths, it shows less susceptibility to atmospheric disturbance and optical contamination from the sun and other sources. Satellite-based wind measurements are used for weather forecasts and meteorological studies. “Space-borne Doppler wind LIDAR is now regarded as the most promising way to meet the need for global wind data requirements and to fill gaps in the wind data provided by other methods,” said Xia.
Upgraded optical components
The optical setup for the new Doppler wind LIDAR contains just one laser source, one detector and a single-channel Fabry-Perot interferometer that converts the Doppler shift into photon number variations of the backscatter signals. Using a Fabry-Perot interferometer made of optical fibers rather than one consisting of many individual optical components made the system robust and stable enough to use in harsh environments such as aboard aircraft or satellites.
The new system also includes one of the fastest detectors available for single photon counting, a superconducting nanowire single photon detector (SNSPD). This detector improved the LIDAR’s performance compared to the InGaAs avalanche photodiodes typically used to detect 1.5-micron light.
“The high detection efficiency and low dark count rate of the SNSPD means that the weak signal from the backscattered light can be detected with a high signal-to-noise ratio,” said Xia. “Another attractive feature of the SNSPD is its high maximum count rate, which helps avoid detector saturation.”
The researchers tested their system by first examining its stability after calibration. Overall, the system’s measurements varied by less than 0.2 meters per second over 10 days in the lab. They then tested the system outdoors and compared its horizontal wind measurements with measurements from an ultrasonic wind sensor, a non-remote system for measuring wind. On average, the LIDAR measurements were within 0.1 meters per second and 1 degrees for wind speed and direction, respectively.
The researchers are now working to improve the spatial resolution of the Doppler wind LIDAR system and want to make it even more practical to use in the field. They have also founded a company to further develop the system and plan to have a commercial version available next year.
Paper: M. Shangguan, H. Xia, C. Wang, J. Qiu, S. Lin, X. Dou, Q. Zhang, J.-W. Pan, “Dual-frequency Doppler LIDAR for wind detection with superconducting nanowire single-photon detector,” Opt. Lett., Volume 42, Issue 18, 3541-3544 (2017).
DOI: 10.1364/OL.42.003541
Light-Based Method Improves Practicality and Quality of Remote Wind Measurements | News Releases | The Optical Society
Bussard Ramjet
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06 September 2017
Light-Based Method Improves Practicality and Quality of Remote Wind Measurements
Innovative technology could aid hurricane forecasting, aircraft safety and wind energy generation
WASHINGTON —Researchers have developed a new remote sensing instrument based on light detection and ranging (LIDAR) that could offer a simple and robust way to accurately measure wind speed. The detailed, real-time wind measurements could help scientists to better understand how hurricanes form and provide information that meteorologists can use to pinpoint landfall earlier, giving people more time to prepare and evacuate.
“As hurricane Harvey approached the U.S., hurricane hunters flew directly into the storm and dropped sensors to measure wind speed,” said Xiankang Dou, leader of the research team at the University of Science and Technology of China (USTC). “Our Doppler LIDAR instrument can be used from a plane to remotely measure a hurricane’s wind with high spatial and temporal resolutions. In the future, it could even make these measurements from aboard satellites.”
Wind measurements are also crucial for determining safe flying conditions, understanding how pollution moves through the air and efficiently operating wind turbines. Existing high-accuracy wind measurement technologies can be expensive and difficult to operate, leading to gaps in the application of these technologies in situations where they are most useful.
Mingjia Shangguan and Haiyun Xia from the University of Science and Technology of China were part of a research team who developed a new Doppler LIDAR system for accurately measuring the wind. It features a greatly simplified optical setup that makes it robust and stable enough to use in harsh environments such as aboard aircraft or satellites. Image Credit: Quantum LIDAR Laboratory.
“We demonstrated a Doppler wind LIDAR with a simplified optical layout that also substantially enhances the system stability,” said Dou. “Although specialists are typically needed to operate and maintain a sophisticated Doppler LIDAR, we are confident we can develop our approach into a system that will be as easy to use as a smartphone.”
In The Optical Society (OSA) journal Optics Letters, the researchers demonstrated their Doppler wind LIDAR system’s ability to measure horizontal wind speed with high accuracy and showed that the system remained stable throughout a 10-day test period. The researchers say that the stability and accuracy of this new system represents a substantial improvement compared to previously developed direct detection Doppler wind LIDARs.
One important application of LIDAR is in aeronautics, where it can be used on aircrafts or from a ground station to remotely measure air motion. With a vertical spatial resolution of 10 meters, the new system could measure small-scale wind phenomena such as wind shear and the wake turbulence created by an aircraft. A better understanding of these phenomena could improve flight safety and also increase airport capacity by optimizing the separation between aircraft during takeoff and landing.
Using light to measure wind
LIDAR is a remote sensing method that has been used to create high-resolution maps, scan the bottom of the ocean floor and to guide driverless cars. For measuring wind, a LIDAR system emits a laser pulse that propagates through the atmosphere where it interacts with molecules and aerosols. A small amount of the light scatters back towards the LIDAR instrument, where it is collected by a telescope. When wind causes air to move, this causes a Doppler shift that can be detected by the device.
The researchers designed a dual frequency direct detection Doppler wind LIDAR that used a laser emitting 1.5-micron light. Because this wavelength is commonly used in optical communications networks, they were able to build the system using commercially available fiber-optic components, each combining several light-controlling components into a single device. The all fiber construction of the LiDAR system is therefore robust against vibrations and rough operation handling.
Compared to previously developed systems, the new simplified design makes it much easier to configure and align each component, increases stability and lowers the amount of light lost within the system. The new system also requires no calibration after it is initialized and requires no special eye protection.
“For LIDAR systems that will be operated full-time in the field, eye safety is an important consideration,” said Haiyun Xia, the principle investigator of the Quantum Lidar Laboratory at USTC. “Fortunately, the 1.5-micron laser we used exhibits the highest permissible exposure for eye safety in the wavelength range from 0.3 to 10 microns.”
The 1.5-micron wavelength is also ideal for atmospheric wind sensing from satellites because, compared to UV and visible wavelengths, it shows less susceptibility to atmospheric disturbance and optical contamination from the sun and other sources. Satellite-based wind measurements are used for weather forecasts and meteorological studies. “Space-borne Doppler wind LIDAR is now regarded as the most promising way to meet the need for global wind data requirements and to fill gaps in the wind data provided by other methods,” said Xia.
Upgraded optical components
The optical setup for the new Doppler wind LIDAR contains just one laser source, one detector and a single-channel Fabry-Perot interferometer that converts the Doppler shift into photon number variations of the backscatter signals. Using a Fabry-Perot interferometer made of optical fibers rather than one consisting of many individual optical components made the system robust and stable enough to use in harsh environments such as aboard aircraft or satellites.
The new system also includes one of the fastest detectors available for single photon counting, a superconducting nanowire single photon detector (SNSPD). This detector improved the LIDAR’s performance compared to the InGaAs avalanche photodiodes typically used to detect 1.5-micron light.
“The high detection efficiency and low dark count rate of the SNSPD means that the weak signal from the backscattered light can be detected with a high signal-to-noise ratio,” said Xia. “Another attractive feature of the SNSPD is its high maximum count rate, which helps avoid detector saturation.”
The researchers tested their system by first examining its stability after calibration. Overall, the system’s measurements varied by less than 0.2 meters per second over 10 days in the lab. They then tested the system outdoors and compared its horizontal wind measurements with measurements from an ultrasonic wind sensor, a non-remote system for measuring wind. On average, the LIDAR measurements were within 0.1 meters per second and 1 degrees for wind speed and direction, respectively.
The researchers are now working to improve the spatial resolution of the Doppler wind LIDAR system and want to make it even more practical to use in the field. They have also founded a company to further develop the system and plan to have a commercial version available next year.
Paper: M. Shangguan, H. Xia, C. Wang, J. Qiu, S. Lin, X. Dou, Q. Zhang, J.-W. Pan, “Dual-frequency Doppler LIDAR for wind detection with superconducting nanowire single-photon detector,” Opt. Lett., Volume 42, Issue 18, 3541-3544 (2017).
DOI: 10.1364/OL.42.003541
Light-Based Method Improves Practicality and Quality of Remote Wind Measurements | News Releases | The Optical Society
This stuff is exactly what should not be published but patented.
A patent is NOT granted if the research, design, or process is already published in open source.
cirr
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China detects its highest-temperature HDR geothermal energy
2017-09-07 11:11
CGTN Editor: Mo Hong'e
(Photo/CGTN)
China has detected hot dry rock (HDR) at 236 degrees Celsius
in Gonghe County, northwest China's Qinghai Province.
China Geological Survey told CGTN on Wednesday that the HDR was found 3,705 meters beneath the Earth's surface. It is the highest-temperature HDR China has detected since the development of HDR geothermal energy starting in 2012.
Geothermal energy generated by HDR is a potential replacement for fossil fuels and can serve as a clean heating resource for millions in China.
Normally, with an over 150-degree-Celsius temperature, HDR lays 3,000 to 10,000 beneath the Earth's surface. Weather has little influence on the process of extracting power from HDR, and the cost is half the price of utilizing wind and one-tenth of generating solar energy.
Qinghai Province was the first known HDR resource in China. In 2014, geological and mineral resource explorers first found HDR in Qinghai with a temperature as high as 153 degrees Celsius, 2,230 meters beneath the Earth's surface.
Besides for Qinghai Province, Chinese explorers have found HDR in regions including southeast coastal areas, the Northeast Plain and the North Plain. In December last year, China detected HDR in its east Shandong Province with a temperature as high as 110 degrees Celsius at a depth of 1,240 meters beneath the Earth's surface.
The development of HDR geothermal energy started in the 1970s and many countries, including U.S., UK and Australia have set up bases for HDR experimental research.
http://www.ecns.cn/2017/09-07/272580.shtml
2017-09-07 11:11
CGTN Editor: Mo Hong'e
(Photo/CGTN)
China has detected hot dry rock (HDR) at 236 degrees Celsius
in Gonghe County, northwest China's Qinghai Province.China Geological Survey told CGTN on Wednesday that the HDR was found 3,705 meters beneath the Earth's surface. It is the highest-temperature HDR China has detected since the development of HDR geothermal energy starting in 2012.
Geothermal energy generated by HDR is a potential replacement for fossil fuels and can serve as a clean heating resource for millions in China.
Normally, with an over 150-degree-Celsius temperature, HDR lays 3,000 to 10,000 beneath the Earth's surface. Weather has little influence on the process of extracting power from HDR, and the cost is half the price of utilizing wind and one-tenth of generating solar energy.
Qinghai Province was the first known HDR resource in China. In 2014, geological and mineral resource explorers first found HDR in Qinghai with a temperature as high as 153 degrees Celsius, 2,230 meters beneath the Earth's surface.
Besides for Qinghai Province, Chinese explorers have found HDR in regions including southeast coastal areas, the Northeast Plain and the North Plain. In December last year, China detected HDR in its east Shandong Province with a temperature as high as 110 degrees Celsius at a depth of 1,240 meters beneath the Earth's surface.
The development of HDR geothermal energy started in the 1970s and many countries, including U.S., UK and Australia have set up bases for HDR experimental research.
http://www.ecns.cn/2017/09-07/272580.shtml
JSCh
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Researchers Report New Way to Make Dissolving Electronics
Discovery Has Applications for Eco-Friendly Disposal, Data Security and Healthcare
By Jeannie Kever 713-743-0778
September 6, 2017
Cunjiang Yu, Bill D. Cook Assistant Professor of mechanical engineering, center, and co-first authors Xu Wang, left, and Kyoseung Sim, right)
Researchers from the University of Houston and China have reported a new type of electronic device that can be triggered to dissolve through exposure to water molecules in the atmosphere.
The work holds promise for eco-friendly disposable personal electronics and biomedical devices that dissolve within the body. There are also defense applications, including devices that can be programmed to dissolve in order to safeguard sensitive information, said Cunjiang Yu, Bill D. Cook Assistant Professor of mechanical engineering at the University of Houston and lead author of the paper, published in Science Advances.
The field, known as physically transient electronics, currently requires immersion in aqueous corrosive solutions or biofluids. Yu said this work demonstrates a completely new working mechanism – the dissolution is triggered by ambient moisture.
“More importantly, the transient period of time can be precisely controlled,” he said.
That means a biomedical implant could be programmed to disappear when its task – delivering medication, for example – is complete. Sensitive communications could be devised to literally vanish once the message was delivered.
And all those old cell phones littering kitchen drawers? New versions could be programmed to dissolve when they are no longer needed.
“We demonstrate that polymeric substrates with novel degradation kinetics and associated transience chemistry offer a feasible strategy to construct physically transient electronics,” the researchers wrote. “Through the manipulation of the polymer component and environmental humidity, the progress of hydrolyzing polyanhydrides can be managed and thus the dissolution kinetics of (a) functional device can be controlled.”
The time period can range from days to weeks, or even longer, they said.
The model constructed by the researchers works like this: Functional electronic components were built via additive processes onto a film made of the polymer polyanhydride. The device remained stable until ambient moisture triggered a chemical breakdown that digested the inorganic electronic materials and components.
The researchers tested a number of compounds, including aluminum, copper, nickel indium-gallium, zinc oxide and magnesium oxide, and developed various electronic devices, including resistors, capacitors, antennas, transistors, diodes, photo sensors and more, to demonstrate the model’s versatility.
The lifespan of the devices can be controlled by varying the humidity level or by changing the polymer composition, Yu said.
In addition to Yu, authors on the paper include Yang Gao, Xu Wang, Kyoseung Sim, Jingshen Liu and Ji Chen, all from UH, and Ying Zhang and Hangxun Xu of the University of Science and Technology of China.
Researchers Report New Way to Make Dissolving Electronics - University of Houston
Discovery Has Applications for Eco-Friendly Disposal, Data Security and Healthcare
By Jeannie Kever 713-743-0778
September 6, 2017
Researchers from the University of Houston and China have reported a new type of electronic device that can be triggered to dissolve through exposure to water molecules in the atmosphere.
The work holds promise for eco-friendly disposable personal electronics and biomedical devices that dissolve within the body. There are also defense applications, including devices that can be programmed to dissolve in order to safeguard sensitive information, said Cunjiang Yu, Bill D. Cook Assistant Professor of mechanical engineering at the University of Houston and lead author of the paper, published in Science Advances.
The field, known as physically transient electronics, currently requires immersion in aqueous corrosive solutions or biofluids. Yu said this work demonstrates a completely new working mechanism – the dissolution is triggered by ambient moisture.
“More importantly, the transient period of time can be precisely controlled,” he said.
That means a biomedical implant could be programmed to disappear when its task – delivering medication, for example – is complete. Sensitive communications could be devised to literally vanish once the message was delivered.
And all those old cell phones littering kitchen drawers? New versions could be programmed to dissolve when they are no longer needed.
“We demonstrate that polymeric substrates with novel degradation kinetics and associated transience chemistry offer a feasible strategy to construct physically transient electronics,” the researchers wrote. “Through the manipulation of the polymer component and environmental humidity, the progress of hydrolyzing polyanhydrides can be managed and thus the dissolution kinetics of (a) functional device can be controlled.”
The time period can range from days to weeks, or even longer, they said.
The model constructed by the researchers works like this: Functional electronic components were built via additive processes onto a film made of the polymer polyanhydride. The device remained stable until ambient moisture triggered a chemical breakdown that digested the inorganic electronic materials and components.
The researchers tested a number of compounds, including aluminum, copper, nickel indium-gallium, zinc oxide and magnesium oxide, and developed various electronic devices, including resistors, capacitors, antennas, transistors, diodes, photo sensors and more, to demonstrate the model’s versatility.
The lifespan of the devices can be controlled by varying the humidity level or by changing the polymer composition, Yu said.
In addition to Yu, authors on the paper include Yang Gao, Xu Wang, Kyoseung Sim, Jingshen Liu and Ji Chen, all from UH, and Ying Zhang and Hangxun Xu of the University of Science and Technology of China.
Researchers Report New Way to Make Dissolving Electronics - University of Houston
JSCh
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Strong solar flare to affect shortwave communications
Source: Xinhua| 2017-09-07 16:38:48|Editor: Xiang Bo
BEIJING, Sept. 7 (Xinhua) -- A strong solar flare may affect shortwave communications on earth, but the disruptions in China will be minor, the Chinese Academy of Sciences (CAS) said Thursday.
According to the CAS National Space Science Center, an X9.3-class solar flare emitting from a group of sunspots codenamed AR 2673 was spotted at 7:53 p.m. Wednesday.
The sunspots have triggered solar flares more than 10 times since Sunday and may continue to cause large flares in the following days, CAS said in a statement.
They are the strongest spotted since 2005 and likely to impact earth on Friday night or Saturday, according to CAS.
The flares may also lead to strong disturbances in the earth's magnetosphere, ionosphere and upper atmosphere, and affect the performance and safety of satellites, the statement said.
A solar flare is a violent explosion in the sun's atmosphere caused by huge magnetic activity. The flares produce large amounts of radiation that can affect the earth's ionosphere and disrupt radio communications.
Source: Xinhua| 2017-09-07 16:38:48|Editor: Xiang Bo
BEIJING, Sept. 7 (Xinhua) -- A strong solar flare may affect shortwave communications on earth, but the disruptions in China will be minor, the Chinese Academy of Sciences (CAS) said Thursday.
According to the CAS National Space Science Center, an X9.3-class solar flare emitting from a group of sunspots codenamed AR 2673 was spotted at 7:53 p.m. Wednesday.
The sunspots have triggered solar flares more than 10 times since Sunday and may continue to cause large flares in the following days, CAS said in a statement.
They are the strongest spotted since 2005 and likely to impact earth on Friday night or Saturday, according to CAS.
The flares may also lead to strong disturbances in the earth's magnetosphere, ionosphere and upper atmosphere, and affect the performance and safety of satellites, the statement said.
A solar flare is a violent explosion in the sun's atmosphere caused by huge magnetic activity. The flares produce large amounts of radiation that can affect the earth's ionosphere and disrupt radio communications.
JSCh
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Sep 7, 2017
Large-area perovskite films go solvent- and vacuum-free
Researchers at Shanghai Jiao Tong University in China and the Swiss Federal Institute of Technology have developed a new technique to deposit high-quality large-area perovskite films that does not require solvents or vacuum processing. The method produces homogenous films with relatively few defects, which leads to a record efficiency of 12.1% for a solar module made from a methylammonium lead halide film that is just over 36 cm2 in size.
A perovskite solar module with a size of 36 cm2
Organic-inorganic hybrid perovskites, which have the chemical formula (CH3NH3)PbX3 (where Pb is lead and X can be iodine, bromine or chlorine), are one of the most promising thin-film solar-cell materials around today thanks to the fact that they can absorb light over a broad range of solar-spectrum wavelengths. The power-conversion efficiency (PCE) of solar cells made from these materials has gone from just 3% to more than 22% in the last eight years, which means that their PCE is now comparable to that of silicon-based solar cells.
For such cells to be widely employed and commercialized, however, we need large-area (1 m2), uniformly high-quality perovskite films from which to make the devices. This is because perovskite-based cells cannot be easily scaled up. Indeed, their PCE decreases from more than 20% to about 10% when they are increased in size from 0.1 cm2 to 25 cm2.
Converting amine complex precursors to perovskite films
A team led by Liyuan Han in China and Michael Grätzel in Switzerland has now developed a new technique to produce large-area methylammonium lead halide (CH3NH3PbI3) perovskite films that relies on rapidly converting amine complex precursors (CH3NH3I·mCH3NH2 (where m is close to 3) and PbI2·nCH3NH2 (where n is close to 1) to perovskite films and then applying pressure to them.
The deposited films are free of pinholes and are highly uniform, say the researchers. “Our technique has the advantage that it does not require any toxic or irritating solvents like N,N-dimethylformamide, dimethyl sulphoxide (DMSO) or gamma-butyrolactone, unlike conventional methods to produce these cells,” says team member Xudong Yang. “It does not produce any waste either and no thermal annealing is required. The technique also works in air and at low temperatures, making it more cost-friendly and environmentally friendly overall.
And that is not all, the pressure-processing step at the end is better than the spin-coating method that is widely employed for depositing perovskite films, he, tells nanotechweb.org.
The film produced by the new technique is highly uniform over a large area (36.1 cm2) with only a 2% variation in film thickness and the grains in the material are around 0.8-1.0 microns in size, which is three to four times bigger than those in spin-coated processed film. The researchers succeeded in making a photovoltaic module with a PCE of 12.1% from such a film.
According to the researchers, reporting their work in Nature doi:10.1038/nature23877, the technique will be useful for growing perovskite crystals, which could greatly reduce so-called trap states and further enhance the photovoltaic performance of these materials. “It could be then used to produce low-cost optoelectronics devices, like light-emitting diodes or laser diodes on a large scale,” adds Han.
About the author
Belle Dumé is contributing editor at nanotechweb.org
Large-area perovskite films go solvent- and vacuum-free - nanotechweb.org
Large-area perovskite films go solvent- and vacuum-free
Researchers at Shanghai Jiao Tong University in China and the Swiss Federal Institute of Technology have developed a new technique to deposit high-quality large-area perovskite films that does not require solvents or vacuum processing. The method produces homogenous films with relatively few defects, which leads to a record efficiency of 12.1% for a solar module made from a methylammonium lead halide film that is just over 36 cm2 in size.
A perovskite solar module with a size of 36 cm2
Organic-inorganic hybrid perovskites, which have the chemical formula (CH3NH3)PbX3 (where Pb is lead and X can be iodine, bromine or chlorine), are one of the most promising thin-film solar-cell materials around today thanks to the fact that they can absorb light over a broad range of solar-spectrum wavelengths. The power-conversion efficiency (PCE) of solar cells made from these materials has gone from just 3% to more than 22% in the last eight years, which means that their PCE is now comparable to that of silicon-based solar cells.
For such cells to be widely employed and commercialized, however, we need large-area (1 m2), uniformly high-quality perovskite films from which to make the devices. This is because perovskite-based cells cannot be easily scaled up. Indeed, their PCE decreases from more than 20% to about 10% when they are increased in size from 0.1 cm2 to 25 cm2.
Converting amine complex precursors to perovskite films
A team led by Liyuan Han in China and Michael Grätzel in Switzerland has now developed a new technique to produce large-area methylammonium lead halide (CH3NH3PbI3) perovskite films that relies on rapidly converting amine complex precursors (CH3NH3I·mCH3NH2 (where m is close to 3) and PbI2·nCH3NH2 (where n is close to 1) to perovskite films and then applying pressure to them.
The deposited films are free of pinholes and are highly uniform, say the researchers. “Our technique has the advantage that it does not require any toxic or irritating solvents like N,N-dimethylformamide, dimethyl sulphoxide (DMSO) or gamma-butyrolactone, unlike conventional methods to produce these cells,” says team member Xudong Yang. “It does not produce any waste either and no thermal annealing is required. The technique also works in air and at low temperatures, making it more cost-friendly and environmentally friendly overall.
And that is not all, the pressure-processing step at the end is better than the spin-coating method that is widely employed for depositing perovskite films, he, tells nanotechweb.org.
The film produced by the new technique is highly uniform over a large area (36.1 cm2) with only a 2% variation in film thickness and the grains in the material are around 0.8-1.0 microns in size, which is three to four times bigger than those in spin-coated processed film. The researchers succeeded in making a photovoltaic module with a PCE of 12.1% from such a film.
According to the researchers, reporting their work in Nature doi:10.1038/nature23877, the technique will be useful for growing perovskite crystals, which could greatly reduce so-called trap states and further enhance the photovoltaic performance of these materials. “It could be then used to produce low-cost optoelectronics devices, like light-emitting diodes or laser diodes on a large scale,” adds Han.
About the author
Belle Dumé is contributing editor at nanotechweb.org
Large-area perovskite films go solvent- and vacuum-free - nanotechweb.org
Han Chen, Fei Ye, Wentao Tang, Jinjin He, Maoshu Yin, Yanbo Wang, Fengxian Xie, Enbing Bi, Xudong Yang, Michael Grätzel & Liyuan Han. A solvent- and vacuum-free route to large-area perovskite films for efficient solar modules. Nature (2017). DOI:10.1038/nature23877
cirr
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China to phase in 14nm semiconductor process in 2018, says top tech master
Jean Chu, Taipei; Willis Ke, DIGITIMES
[Tuesday 22 August 2017]
China is proceeding with systematic deployments in 14nm semiconductor fabrication equipment, process, packaging and materials, which will be fully industrialized in 2018. And the nation will render major support to the development of 5-7nm procesess and 3D memories under its 13th Five-year Development Plan running 2016-2020, according to Ye Tianchun, director of the Institute of Microelectronics under the Chinese Academy of Science.
Customs statistics showed that China imported US$227 billion worth of IC products in 2016, twice its crude oil imports for the year, but the nation's IC exports reached only US$61.4 billion. The huge trade deficit was due mainly to China's lack of high-end chip products for exports, Ye said.
Ye said that IC technologies are the most crucial cornerstone of the information technology era, and the "grain" of modern industries, as ICs are now totally indispensable to computers, smartphones, home appliances, automobiles, high-speed rail system, electrical grid, medical instrument, robots and industrial control, among others.
Also serving as China's National Science and Technology Major Master, Ye stressed that the nation's IC industrial chains are expected to reach advanced international levels by 2030, when a certain semiconductor firms will be able to emerge as top players in the world. Inspired by more policy support from the government, he added, China's semiconductor firms are expected to spend more on the development of advanced processes in the coming years.
US 'Section 301' investigation may target semiconductor
The US has recently launched a "Section 301" investigation to determine whether China's intellectual property policies and practices are unreasonable or discriminatory. It is widely speculated that the US will list semiconductor among high-tech sectors subject to investigations in a bid to dampen the rise of China's semiconductor industry.
In response, Ye said that over the years, advanced countries in the West have rigidly blocked key IC technologies from flowing into China, and the best way to counter is for China makers to pursue technology innovations and breakthroughs on their own.
As early as 2000, the central governmemnt issued a set of policy guidelines for the development of the IC industry, and in 2008 it listed core electronics components, high-end chips and basic software products, as well as very-large-scale integration IC fabrication equipment as key technology development projects for implementation. In 2014, the government set up National IC Industry Investment Fund (Big Find), at a scale of CNY120 billion(US$18.03 billion), all highlighting China's determination to develop the semiconductor industry on its own, according to Ye.
He stressed that following years of concerted efforts by the government and enterprises, China's semiconductor industry is showing increasingly strong technology and production prowess, given the fact massive amount of chips designed and manufactured by domestic companies have been adopted by China's leading vendors of smartphones, communication equipment and smart cards.
http://www.digitimes.com/news/a20170822PD208.html?mod=0
The gap between China and its main rivals is beginning to close. India? @Bussard Ramjet
China will leap-frog the 10nm process and jump to 5-7nm processes in or around 2021.
Jean Chu, Taipei; Willis Ke, DIGITIMES
[Tuesday 22 August 2017]
China is proceeding with systematic deployments in 14nm semiconductor fabrication equipment, process, packaging and materials, which will be fully industrialized in 2018. And the nation will render major support to the development of 5-7nm procesess and 3D memories under its 13th Five-year Development Plan running 2016-2020, according to Ye Tianchun, director of the Institute of Microelectronics under the Chinese Academy of Science.
Customs statistics showed that China imported US$227 billion worth of IC products in 2016, twice its crude oil imports for the year, but the nation's IC exports reached only US$61.4 billion. The huge trade deficit was due mainly to China's lack of high-end chip products for exports, Ye said.
Ye said that IC technologies are the most crucial cornerstone of the information technology era, and the "grain" of modern industries, as ICs are now totally indispensable to computers, smartphones, home appliances, automobiles, high-speed rail system, electrical grid, medical instrument, robots and industrial control, among others.
Also serving as China's National Science and Technology Major Master, Ye stressed that the nation's IC industrial chains are expected to reach advanced international levels by 2030, when a certain semiconductor firms will be able to emerge as top players in the world. Inspired by more policy support from the government, he added, China's semiconductor firms are expected to spend more on the development of advanced processes in the coming years.
US 'Section 301' investigation may target semiconductor
The US has recently launched a "Section 301" investigation to determine whether China's intellectual property policies and practices are unreasonable or discriminatory. It is widely speculated that the US will list semiconductor among high-tech sectors subject to investigations in a bid to dampen the rise of China's semiconductor industry.
In response, Ye said that over the years, advanced countries in the West have rigidly blocked key IC technologies from flowing into China, and the best way to counter is for China makers to pursue technology innovations and breakthroughs on their own.
As early as 2000, the central governmemnt issued a set of policy guidelines for the development of the IC industry, and in 2008 it listed core electronics components, high-end chips and basic software products, as well as very-large-scale integration IC fabrication equipment as key technology development projects for implementation. In 2014, the government set up National IC Industry Investment Fund (Big Find), at a scale of CNY120 billion(US$18.03 billion), all highlighting China's determination to develop the semiconductor industry on its own, according to Ye.
He stressed that following years of concerted efforts by the government and enterprises, China's semiconductor industry is showing increasingly strong technology and production prowess, given the fact massive amount of chips designed and manufactured by domestic companies have been adopted by China's leading vendors of smartphones, communication equipment and smart cards.
http://www.digitimes.com/news/a20170822PD208.html?mod=0
The gap between China and its main rivals is beginning to close. India? @Bussard Ramjet
China will leap-frog the 10nm process and jump to 5-7nm processes in or around 2021.Similar threads
